OF REPTILES AND BIRDS. 



15 



2, presents the following 

 A has grown broader, and 



ness throughout. They run obliquely downwards, one set from left to right, the other 

 from right to left, crossing the first at nearly right angles. 



In a section further back, the ridge is wanting, but the other differences are less 

 important. 



A section further forward through the line 1 of fig 

 peculiarities, requiring especial notice, cut 4. The ridge 

 at the same time thinner in the median line and thicker 

 at the sides. Immediately underneath it are two small 

 bundles of longitudinal fibres, probably the continuation 

 of r in cut 2. The principal longitudinal muscles, l' 

 are still of considerable size, but lie more to the upper 

 side. The circular fibres, c, are much reduced. An addi- 

 tional pair of longitudinal muscles, l'", appear at the 

 sides, and I think must correspond to Duvernoy's longi- 

 tudinal lingual muscle (VI, plate 5, figs. 6 and 7, &). 

 The muscular sheath of the extension of the hyoid, has 

 separated into two portions, one, M', superior, triangular 

 in section (the apex pointing upwards), the muscular 

 fibres running all transversely and nearly parallel to 

 one another ; the second, M", inferior, the fibres circular 

 in direction and also approximately parallel among them- 

 selves. From the examination of these sections it is evi- 

 dent that Duvernoy's description is very far from complete. 



It is impossible to trace in the Chamaeleon, as could so readily be done in Ameiva, 

 the homologies with the snake's tongue, from the mere comparison of transverse sections. 

 I therefore the more regret that I had no material to study the origin of muscles and the 

 structure of the hyoidean apparatus more accurately. It is also unfortunate that the 

 single tongue which I obtained was not sufficiently well preserved to permit making 

 sections thin enough for a proper histological examination. The large longitudinal and 

 circular muscles are, it may be conveniently assumed in default of positive knowledge 

 homologous with the somewhat similar muscles of Ameiva and Ancistrodon. The dorsal 

 muscular ridge, and the remarkable central cylinder appear to be special adaptations 

 as is also the strangely constructed extension of the hyoid. 



I hope that some European naturahst, more favorably circumstanced for obtaining 

 fresh material, will investigate the structure of this very singular and extremely 

 interesting tongue. 



Cut 4. Chamaeleon dilepis. Section of the 

 tongue, line 1, Fig. 2. V, blood vessel. A, 

 dorsal ridge ; 1 ', I ", 1 '", longitudinal muscles ; 

 Ml, upper — Af '/, lower segment of the mus- 

 cular cylinder around the hyoid, which has 

 fallen out. x 12 diam. 



IV. The Tongue of Mimus. 



The tongue of Mimus, fig. 3, has the typical avian peculiarities. Its base is supported 

 by the hyoid and its cornu, — the free portion by the double entoglossum. The 

 general shape of the tongue is sufl&ciently shown in fig. 3, A, B. The two sections 

 represented in cuts 5 and 6, were taken approximately in the planes indicated 

 respectively by the lines 1 and 2, on fig. 3 B. The first section cut 5, is through the 



