388 ANATOMY OF VERTEBRATES. 



tongue. The buccal orifice, fig. 9, a, is little wider than is needed 

 for the protrusile and retractile movements of that slender organ, 

 so singularly modified for the prehension of the Termites which 

 form the staple food of the so-called ' anteaters.' The tongue 

 in Myrmecophaga jubata, ib. b, 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 papillse anywhere visible are two fossulate ones, two lines 

 apart, situated on the dorsum, about two inches in advance of 

 the termination of the fraenum. A linear groove, commenc- 

 ing two inches from the base of the tongue, extends along the 

 dorsum to within four inches of the apex. The muscular sub- 

 stance of the free part of the tongue is formed by the intrinsic 

 fibres, or ( linguales,' and by the lingual portions of the sterno- 

 glossi, genio-glossi, and epihyo-glossi (p. 23). The buccal mem- 

 brane 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 a thin glandular stratum behind the mem- 

 brane 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 forward and 

 upward : this ridge is about two lines in breadth, and bends down 

 so as to leave a groove between it and the lower membrane 

 of the mouth. Introduced 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 of the mouth. In the 

 two-toed Anteater they take the form of a horny molar plate on 

 each side of both jaws. The cavity of the mouth quickly expands 

 as it passes backward, and acquires its greatest breadth opposite 

 the base of the tongue, ib. g, g, having there, in Myrmecophaga 

 jubata, a diameter of from four to five inches. The thin mem- 

 brane, over which the diverging fasciculi of the sterno-glossi and 

 hyo-glossi spread, is capable of considerable dilatation : it serves 

 as a sheath for the spirally retracted tongue, and may also form 

 a temporary receptacle for the Termites, there blended with the 

 more alkaline and solvent salivary secretion of the parotids, 

 after being pounded by the tongue against the callous ridges, 

 before they are finally swallowed: the singular backward ex- 

 tension of the fauces and nasal passages appears to relate, in 

 part, to the presence and function of this receptacle. The buccal 

 cavity gradually contracts beyond the receptacle to the hyoid 



