ORAL CAVITY 



235 



with numerous mucous glands, and is developed into papillae of vary- 

 ing shapes, some sensory, and in some cases they become cornified 

 and efiScient organs of rasping (monotremes, cats). 



The skeleton of the mammaUan tongue (hyoid apparatus) varies 

 considerably. In its most complete development it consists of a body 

 (copula of the hyoid and first branchial) in the median line, which 

 bears two pairs of cornua. The anterior pair (lesser horns of human 

 anatomy) are usually elongate, and consist of a series of ossicles (p. 

 80) connecting the body with the otic region of the skull. The 

 second pair (greater cornua of man) are occasionally absent. In man 



Fig. 248. Fig. 249. 



Fig. 248 — Ventral and side views of tongue of Stenops gracilis, after Weber. /, 

 lateral margin of sublingua; m, plica mediana. 



Fig. 249. — Section through lyssa of late dog embryo, after Nussbaum. c, cartilage 

 of lyssa, cl, capsule of lyssa; ml, muscles of tongue; nU, longitudinal and transverse 

 muscles of lyssa; s, septum of tongue. 



the greater part of the anterior cornua is represented by the stylo- 

 hyoid ligament, the proximal portion being fused to the skull as the 

 styloid process. 



Oral Glands 



In the cyclostomes there is a large, so-called, 'salivary gland' of 

 unknown function, opening into the mouth on either side below the 

 tongue. With this exception, glands are lacking from the mouths of 

 aquatic ichthyopsida. With the assumption of pulmonate respira- 

 tion and more terrestrial habits, the mouth is no longer constantly 

 bathed with water and glands appear, increasing in number and com- 



