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Show 144 MR. W. A. FORBES ON THE STRUCTURE [Mar. 2, As was first pointed out by Lund, half a century ago, a singular exception to this rule obtains in the Tanagers of the genus Euphonia1. From his description (quoted below) and figures, it is quite evident that Lund considered that there was, in these birds, an intermediate zone devoid of glands or muscles, between the proventriculus and the commencement of the small intestine, and that a small lateral diverticulum springing from this zone was also present, representing the true, though rudimentary, gizzard. Lund found, as he believed, this state of things in three species of Euphonia, whilst the normal type of stomach existed in sixteen other species of Tanagers which he examined. Lund's description has frequently been copied since in various text-books, and his figures at least three times reproduced2. Mr. Sclater having called m y attention to this subject, I have been able, thanks to the resources of the Prosector's department and to the material afforded by M r . Salvin, to reexamine this question. I have been able repeatedly to dissect specimens of various species of Euphonia, both preserved in spirit and quite fresh. I can fully confirm Lund's description in all points, except as regards the presence of a small lateral diverticulum from the alimentary canal, of which I have never been able to find the slightest trace, though I have always carefully looked for it. Fig. 2 (p. 145) will show the structure of this part of the alimentary canal, with the parts as little disturbed as possible, but with the stomach &c. cut open from behind, in a perfectly fresh specimen of Euphonia violacea. A s will be seen, between the glandular proventriculus and the villi-covered duodenum a narrow zone is interposed, with its walls in no degree thickened, but thin aud membranous, and of rather greater calibre than the adjacent parts, there being no pyloric constriction. Moreover there is none of that approximation of the cardiac and 1 In a pamphlet entitled " De genere Euphones, prassertim de singulari canalis intestinalis structura in hocce avium genere, autore Dr. Peter Wilhelm Lund," published at Copenhagen in 1829 (31 pages and 1 plate). This pamphlet being rather scarce, I here give Lund's own words:- " § 13 (p. 12). Ubi incipit intestinum tenue, ibi conspicitur in externa super-ficie angustae illius zona?, qua? locum ventriculi occupare videtur, minima quaedani protuberantia, cui intus respondet levis quaedam impressio. Opaca est parvula haec protuberantia; quare in parietibus iibras musculosas contineat non dubito; hoc vero, propter minimam ejus molem, decidere vix valebis Ad earn sententiam maxime inclinare animam, ut statuam veruni esse hoc ventriculi analogon, haud diffiteor. " § 14. Haec si vera judicetur cogitandi ratio, referas licet structuram hujus avis ad formam avium generalem; ita enim habebimus, uti solet, musculosum nostrum organon e latere intestini exortum, interque proventriculum et intestinum tenue positum; neque a forma generali avium aberrat haec structura, nisi in eo, quod ad minimum quoddam rudimentum reductus est ventriculus: contra, si zonam illam, de qua mentionem fecimus, angustam pellucidamque, quae inter proventriculum et intestinum tenue invenitur, analogon esse ventriculi statua-mus, constantes duo maximeque essentiales ventriculi avium characteres sub-ruentur, in musculosa structura^ortuque laterali positi." 2 Oarus and Otto, Tab. Anat. Comp. Illustr. 1835, pt. iv. tab. vi. figs. 4, 5; Wagner, Icones Zool. iii. t. xi. figs. 3, 4; Bruhl, Zoot. aller Thierkl. Lief. iii.. pl. ix. fig. 13 a. |