20 MINOT OlSr THE TONGUE OF REPTILES AND BIRDS. 



EXPLANATION OF THE PLATE. 



The figures are all taken from Ancistrodon piscivorus, excepting Figs. 1, 2, 3 and 12. The magnifica- 

 tion, when the figures are not natural size, is given on the plate itself. The outlines of all the drawings 

 taken from microscopical prej)arations, were made with the camera lucida. The minuter details were orig- 

 inally not drawn with entire accuracy. In the lithograj)h the minuteness and finish of the original draw- 

 ings is lost, and the figures are not faithful except in their gross effect. 



Fig. 1. Crotalus durisus. Tongue and its sheath, seen from the dorsal surface, the floor of the mouth 

 having been removed except around the opening of the sheath, m, out of which, projects the forked extrem- 

 ity of the tongue ; a, point where the sheath and the tongue unite. A, B, C, first, second apd third pairs of 

 lingual nerves, each nerve is accompanied by connective tissue and an artery ; Sy, hyoid cartilage. 



Fig. 2. Dorsal view of the tongue of Chamaeleon dilepis, retracted. 



Fig. 3. Mimus polyglottus. Tongue. A, dorsal — JB, lateral view. 



All the remaining figures, except fig. 12, are from Ancistrodon. 



Fig. 4. Enlarged view of part of the nerve B, in fig. 5. 



Fig. 5. Section through the base of tip. 



Fig. 6. Section just behind the fork. 



Fig. 7. Section through the anterior portion of the free segment of the tongue. 



Fig. 8. Section through the middle of the free segment. 



Fig. 9. Section a short distance in front of the point of attachment. 



Fig. 10. Section taken a little in front of the entrance of the hypoglossal nerve, fig. 1, O, into the tongue. 



Fig. 11. Section some distance behind the entrance of the hypoglossal nerve into the tongue (fig. 1. C). 



N.B. Figs. 5-9 are through an extended, figs. 10-11 through a retracted tongue. The levels at which the 

 sections represented in figs. 7-11, were taken, are approximately indicated by the numbered transverse lines 

 in fig. 7. 



Fig. 12. Ameiva surinamensis. Transverse section through the middle of the free part of the tongue ; to 

 compare with fig. 8. 



Fig. 13. Transverse section of the wall of a lingual artery, to show the lining endothelium, ep. 



Fig. 14. Epithelium near the fork of the tongue. 



Fig. 15. Epithelium from the base of one of the tips. 



EXPLANATION OF THE 



a. Point where the tongue and sheath unite. 



A. Anterior lingual nerve. 



jB. Middle lingual nerve. 



C. Posterior lingual nerve, the hypoglossus. 



C Anterior lingual branch of the hypoglossus. 



C" Posterior lingual branch of the hypoglossus. 



C. gl. Ceratoglossal muscle. 



Ep. Epithelium, 



