34 



THE BONES AND JOINTS. 



14. The vomers, vomer (Figs. 19, 20 v). 



Cuvier, I.e., p. 389, PI. XXIV, Figs, i, 2 1 1. — Dugès, n. 6.— Parker 

 and Bettany, I.e., vomer. 



A pair of flat bones, placed liorizontally on the under surface of 

 the cartilaginous nasal capsule in the triangular space between the 

 palatine bone and the anterior portion of the arch of the jaw. They 

 limit the outer border of the floor of this caj^sule, which lies in 

 a groove on the dorsal surface of the bone. The outer border of 

 each bone has three processes, and between them two notches ; the 

 hinder of these notches bounding the posterior nares. The inner 

 borders of the two bones touch, and the under surface of each bears 

 a transverse row of small, pointed teeth. 



Fo-. 21. 



15. The mandible, maxilla inferior (Fig. 31). 



Cuvier, Z.c.,p. 398, PI. XXIV, Figs, i, irst. — Duges, n. 16, 17, 18, 19. — 

 Parker and Bettany, I.e., mandibular arch. 



The mandible consists of two bony arches united by ligament in 

 the middle line, and each formed of four pieces. These are, (i) the 



angulosplenial, a 

 strong', bony piece 

 (Fig.2iC,^i,^i), 

 which forms the in- 

 ferior and internal 

 part of the lower 

 jaw; below, it ex- 

 tends posteriorly, as 

 far as the articula- 

 tion ; in front, it is 

 attached to the den- 

 tary. In the greater' 

 part of its length it 

 has a groove directed 

 upwards and out- 

 wards (C, b), and 

 above has a pro- 

 cess which repre- 

 sents the processus 

 coronoidens : (2) the 

 dentary [A 2, B 

 2), a bony lamella 

 which rests on the 



A Mandible of Ra7ia esculenta, from above, nat. size. 



B External view of left side, 1 , • . . 



„ . , , . , !■ twice nat. size. 



C Angiilosplenial, I 



1. Angulosplenial. 



2. Dentaiy. 



3. Mentonieckelian. 



4. 4' Meckel's cartilage. 



(( . Rudimentary processtis coronoidens. 

 b. Groove for Meckel's cartilage. 



