there are only three branchial arteries formed on each side of the neck by the subdivision of the aorta; each of these vessels gives a branch to one of the gills. The arteries of the head and neck are derived from the branchial veins or vessels which carry back the blood which has passed through the gills, and from communicating vessels passing between the arteries and veins at the roots of the gill stalks. The pulmonary artery is given off at the place where the posterior branchial artery and vein meet and join with the anterior ones to form the roots of the descending aorta. From the drawing of the Amphiuma Didactylus by Dr Pockels, published by Rusconi (which Cuvier has shewn was erroneously taken by these anatomists for the siren), it appears that the distribution of the branchial arches in this animal resembles more that of the larva of the salamander, there being four branchial arteries, the three anterior of which supply the gills, while the posterior, a fourth, alone is ramified on the sae of the lungs.* (To be concluded in our next.) Explanation of the Plates. In all the figures, the following letters indicate the different parts :— a, The ventricle. a', The auricle of the heart. b, The bulb of the aorta. b', The ascending aorta. c, The liver. d, The stomach. d', The œsophagus. e, The mouth. e', The anus. f, The eye. g, The anterior. g, The posterior extremities. H, The external gills, the stalks. h, The leaflets. I, The internal gills or branchial plates. i, The leaflets or fringe. λ, The operculum. k, The rectum and cloaca. L, The lungs. 1, The cellular part. "', The trachea. m, The branchial vascular arches. n, The returning vessels or branchial veins. o, The branchial apertures. p, The pulmonary arches or arteries. r, The left; r", The right root of the descending aorta. s, The descending aorta. t, The carotid artery. u, The brachial, and in Figs. 9 and 11 the mammary. w, Communicating vessels of the branchial arches which are obliterated. v, The urinary bladder and allantois. x, The artery of the yolk. y', The vein carrying blood to the yolk. y, The returning vein of the yolk. %, The umbilical artery., The umbilical vein. d, Ductus arteriosus. • For a farther account of these animals, see Configliachi and Rusconi Del Proteo Anguino di Laurenti Monografia. Pavia, 1819, of which an account is given by D. Ellis, Esq., in Vols. iv. and v. of this Journal. Cuvier, Recherches sur les Reptiles douteux, in Humboldt's and Bonpland's Recueil d'Observations, &c.-Mémoires du Museum d'Hist. Nat., tome xiv. 1827. Sur le Genre de Batraciens nommé Amphiume.-Philosoph. Trans. by Shreibers and John Hunter.-Wilson's Illustrations of Zoology. , Inferior maxilla. n, The amnios. vitello intestinalis. The chorion. x, The ductus FISHES. Fig. 1. (From Rathke) Supposed section of the foetus of the Blennius Viviparus, at the middle of foetal life. 2. (From do.) The anterior part of the body of a very young embryo of the same fish magnified seven times, the sac of the yolk and integuments covering it removed. 3. (From do.) The same seen from below; the heart removed; the ab- 4. (From do.) Another embryo farther advanced. The operculum 5. (From do.) The same seen from below. 7. Anterior part of the foetus of the Squalus Max. ; half the natural size, 1. Batrachia. REPTILES. 8. Foetus of the Aquatic Salamander one day after its exit from the egg, seen from below. A, Natural size. 9. (From Rusconi) Head, &c. of the larva of the same animal at the time when the gills are nearly perfected, opened, and seen from above. Magnified. 10. (From the same) Shews the leaflets of the gills forming. 11. (From do.) The vessels in the neck of the adult Salamander. 13. The larva of the frog about 24 days old; shews the connexion of 14. The larva of the frog at the time of the commencement of its transformation, twice the natural size. A, Exhibits the double row of leaflets on the internal gill. 15. (From Swammerdam) The principal arteries of the adult frog. 16. The commencing lungs of the frog; A, in the tadpole on the 18th day, seen from below; B, in the tadpole represented in Fig. 13. seen from the side. 2. Lizards, &c. 17. (From Emmert and Hochstetter) Ovum of the Lacerta agilis, shewing the foetus in its amnios, the yolk and allantois with their vessels. 18. (From Dutrochet) Supposed section of the ovum of the Serpent, shewing the allantois expanding. 19. (From Bojanus) The heart and arterial vessels of the Testudo Europea from behind. BIRDS. 20. Anterior part of the fœtus of the Duck four days and a-half old, seen on the right side. Magnified about seven diameters. 21. (From Baer) Section of the chick in ovo on the fourth day. 22. (From Rathke) Embryo of the chick on the fifth day. Magnified one diameter. 23. (From do.) Longitudinal and vertical section of the head and neck of the chick on the fifth day, shewing the interior of the pharynx and the remains of the branchial apertures. 24. (From do.) Heart and anterior part of the neck of the same embryo, shewing the infer. maxilla and operculum. 25. Posterior view of the heart and interior of pharynx, at a corresponding period, shewing the branchial arches given off by the bulb of the aorta. A, Section of the extremity of the bulb. 26. (From Rathke) A, The lower, and B, The lateral view of the lungs and trachea of the chick on the fifth day, with the oesophagus. 27. (From do.) The same on the sixth day. 28. (From do.) The same on the seventh day. (From do.) The lungs, &c. on the eleventh day, shewing the trachea, aorta, pulmonary arteries, communicating vessels, and the union of the cellular, with the bronchial parts of the lungs. 30. (From Burdach, but reversed.) Diagram shewing the branchial divisions of the aorta of the chick on the lower side of the pharynx, and the mode of their transformation into the aortic and pulmonary vessels. 31. The position of the ductus arteriosi relatively to the œsophagus in the chick about the 12th day. MAMMALIA, 32. (From Bojanus) Sketch shewing the relative position, size, &c. of the allantois and yolk-sac, &c. in the fœtus of the sheep about three weeks old. A, The foetus and umbilical vesicle magnified. B, A small part of the foetal placenta or cotyledon of the calf, shewing the processes of the chorion on which the umbilical vessels are ramified. 33. (From Bojanus) The same in the dog of 24 days. 34. The same in the rabbit of about fourteen days, with the placenta. A, The entire ovum. B, The chorion and umbilical vesicle opened, so as to shew the allantois and placenta. 35. The head and neck of the embryo of the dog of three weeks, represented by Baer, and copied from Fig. 8. of former Essay. 36. The human embryo of about six weeks, in which I found two branchial apertures at least on each side of the neck, the heart exposed. A, The natural size. 37. (From Rathke) Anterior view of the neck of the foetus of the pig, represented in Fig. 9. of former Essay, shewing the branchial aper tures and operculum. 38. Heart and branchial arches in the rabbit, Fig. 34. 39. Diagram of the branchial arches of mammalia, and their transformations, corresponding with that of birds by Burdach. A, Ductus arteriosus of mammalia when just formed. 40. Posterior view of the heart and commencing lungs and trachea of the rabbit, Fig. 34. Magnified three diameters. 41. (From Rathke) The tongue, trachea, and lungs of the foetal horse seen from above, twice the natural size. A, The same seen from below. B, Section. 42. (From do.) Lungs of the pig farther advanced, twice the natural size, seen from below. A, The same, seen from above. B, Section. 43. The heart, lungs, pulmonary and aortic vessels, and ductus arteriosus of the human embryo of ten weeks, twice the natural size. On the Characters and Affinities of certain Genera chiefly belonging to the Flora Peruviana. By Mr DAVId Don, Librarian to the Linnean Society, Member of the Imperial Academy Naturæ Curiosorum, of the Royal Botanical Society of Ratisbon, and of the Wernerian Society of Edinburgh, &c. THE object of the present memoir is an attempt to illustrate some of the more obscure genera published in the Flora Peruviana et Chilensis, a work containing a rich fund of interesting materials; but which, from its plan, it is much to be regretted, is, in many instances, unavailable for the purposes of science, the descriptions being often too meagre, and the details of the plates rarely sufficient for determining satisfactorily the classification of the new genera therein proposed. The examination, however, of authentic specimens in the Herbarium of Ruiz and Pavon, has rendered a task comparatively easy, which otherwise would have been very difficult, if not wholly fruitless. To illustrate the characters of groups already established, and to determine their several stations in the system of Nature, is of much more importance to the advancement of science, than the discovery of new species, or the forming of new combinations. I cannot hope to have been equally fortunate in all cases; but if I have succeeded, even in an approximation to ascertaining the characters and affinities of these genera, my utmost expectations will be fulfilled. CLEOMELLA, Decand. Syst. Linn. HEXANDRIA MONOGYNIA. Ord. Nat. CAPPARIDEÆ, Juss. Calyx monophyllus! 4.fidus: laciniis ovato-oblongis, mucronatis (ut in foliis!) integerrimis. Petala hypogyna, laciniis calycinis alterna, ellipticooblonga, obtusa, subcarnosa, venosissima, integerrima: ungue brevissimo. Stamina 6, æqualia, glandulæ elevatæ magnæ truncatæ inserta: filamenta subcapillaria, glabra: anthera longa, lineares, subtetragonæ, obtusæ, biloculares, basi insertæ, ad floris expansionem spiraliter revolutæ ! lo culis parallelis, bivalvibus, suturâ longitudinali exteriùs dehiscentibus. Ovarium pedicellatum, ovatum, compressum, uniloculare: ovulis pluribus. Stylus brevissimus, glaber. Stigma simplex, truncatum. Capsula pedicellata, compressa, triangularis, truncata, unilocularis, bivalvis, decasperma valvis navicularibus, in angulum prominentem productis (compressione cauli contrario), quasi transversis: sutura intùs magis. prominulæ, funiculis umbilicalibus, complanatis persistentibus instructæ. Semina simplici gyro cochleata, extremitatibus connatis! umbilico i sinu; testa exterior crustacea, lævis; interior cartilagineo-membranacea: albumen nullum. Embryo flexurâ arctâ teres, luteus: cotyledonibus incumbentibus, semicylindricis: radicula his parùm longiore, basi acutâ. Planta (Mexicana) suffruticosa, procumbens, glaber, glauco-virens. Caules plurimi, teretes, ramosissimi. Folia alterna, petiolata, ternata: foliolis breviter stipitatis, cuneiformibus, retusis cum mucronulo reflexo, integerrimis, 3--4linearibus. Petioli semicylindrici, 3--6 lineas longi. Stipulæ 2, setacea, brevissima. Flores axillares, solitarii, pedunculati, albi. Pedunculi subcapillares, semipollicares. 1. C. mexicana. Cleomella mexicana, Decand. Prod. 1. p. 237. Cochlearia trifoliata, Sesse et Mocinno MSS. Hab. in Mexico. Sesse et Mocinno. 4 (V. s. sp. in Herb. Lamb.) A genus first proposed by my candid and learned friend M. De Candolle, in the second volume of his Prodromus Systematis Naturalis Regni Vegetabilis, where the essential characters are given; but I have thought that a detailed description, derived from the examination of several complete specimens, might be desirable, especially as it is probable M. De Candolle had not an opportunity of seeing specimens of it, but had derived his knowledge of the genus from the unpublished drawings of the Flora Mexicana. This genus is interesting, as exhibiting, both in its habit and structure, an evident affinity to the Tropaolea, which I have elsewhere proposed to place near to Crucifera and Capparidea. The Balsamineæ, which I also formerly proposed to add to this class, I am now fully persuaded must be arranged near to Violea-to which, even in the nervation and dentation of their leaves, they exhibit a closer affinity. The placentæ in Cleomella are very prominent, and extend sometimes considerably within the capsule, constituting a sort of partition; and as the rudiment of a connecting membrane, analogous to the dissepiment in Cruciferæ, is occasionally observable in the young ovarium, it is probable that that organ is wholly absorbed in the very early stage of the ovarium, in Capparideæ. OCTOBER-DECEMBER 1830. H |