THE GREAT ANTEATER. 129 



genio- and sterno-glossi, the fifth pair of nerves (PI. XXXIX. fig. 2, o), which have 

 arched ahnost transversely beneath the lower part of the gular pouch, converge to 

 penetrate the tongue at the base of the fraenum. 



Ejjihyoglossi. — Beneath the insertions of the geniohyoidei (PL XXXVIII. fig. 1,1,1), a 

 pair of more slender muscles [ib. k, k) come off from the median ends of the epihyals. 

 These muscles, after a brief course, expand into a thin layer, resolve themselves into 

 separate fasciculi, and combine an inch in advance of their origin to form a layer about 

 eight Hues in breadth below the middle line of the postlingual part of the mouth ; which 

 layer (/f) slightly diminishes in size as it approaches the commissure of the sterno- 

 glossi {h), and, with them, penetrates the back part of the frteaum linguae. The antero- 

 posterior diameter of the base of the tongue, where it rises freely from the buccal 

 membrane (PI. XXXVIII. fig. 2, o,p,i), is three and a half inches. The convergence 

 of the sterna- and genio-glossi, with the connecting frtenal fold, forms a triangle, from 

 the apex of which the tongue, 6, assumes its vermiform shape, gradually diminishing 

 from a breadth of eight lines to the obtuse apex which is one Une in breadth, the length 

 of this free part of the tongue being eighteen inches. 



The tongue is covered by a smooth shining epithelium, which begins to present a 

 softer, more vascular or mucous character fourteen inches from the apex ; but the only 

 papillae anywhere present are two fossulate ones, 'papillae vallatae' (PI. XXXIX. fig. 3,/), 

 forming a pair, two lines apart, situated on the dorsum of the tongue about two inches 

 in advance of the termination of the fraenum. A linear groove, commencing two inches 

 from the base of the tongue, extends along the dorsum to within four inches of the apex. 



The muscular substance of the free part of the tongue is formed by the lingual por- 

 tions of the sternoglossi, by the genioglossus, and by the proper ' linguales' muscles. 



The buccal membrane (PI. XXXIX. fig. 3, p, q) is smooth, perforated at its lateral and 

 inferior parts, and also superiorly beyond the bony palate, by innumerable very minute 

 orifices, from a quarter of a line to one line apart, by which the secretion of the thin 

 glandular stratum before described enters the mouth. 



Four inches in advance of the angle of the jaw, near the lower border of the ramus, 

 a longitudinal ridge or low fold of the buccal membrane begins to rise, increasing in 

 depth and assuming a callous hardness as it extends forwards and upwards : this ridge 

 (PI. XXXIX. fig. 3, r) is about two lines in breadth, and bends down so as to leave a 

 groove between it and the lower membrane of the mouth. It is possible that the 

 Termites may be crushed by the action of the tongue against these two callous ridges, 

 which seem to occupy the place of teeth on each side the mouth. 



The cavity of the mouth quickly expands as it passes backward and acquires its 

 greatest breadth opposite the base of the skull and of the tongue (ib. fig. 3, p, q), having 

 there a diameter of from four to five inches. The thin membrane, over which the 

 diverging fasciculi of the sternoglossi and hyoglossi spread, is capable of considerable 

 dilatation, and may serve, therefore, as a temporary receptacle for the Termites, where 



VOL. IV. PART IV. U 



