410 MANUAL OF ZOOLOGY sect. 



hallux or great toe — is turned inwards or towards the 

 median plane of the body. 



The skin is soft and slimy, owing to the secretion of 

 mucous glands ; there is no trace of an exoskeleton. 



The vertebral column (Fig. 247) is remarkable for its 

 extreme shortness ; it consists of only nine vertebrae (V. 1- 

 V. 9), the last followed by a slender, bony rod, the urostyle 

 (UST). The second to the seventh vertebrae are similar 

 in character. The centrum (B, en) is somewhat depressed, 

 and has a concave anterior and a convex posterior face — a 

 form known as procalous. Each half of the neural arch 

 consists of two parts, — a pillar-like pedicle {pel) springing 

 from the centrum and extending vertically upwards, and a 

 flat, nearly horizontal lamina {lm), forming, with its fellow, 

 the roof of the neural canal. 



The zygapophyses (a. zyg) or yoking processes are far 

 better developed than in any fish. Laterally the neural 

 arch gives off on each side a large outstanding transverse 

 process {Jr. pr) ; its crown is produced into a very small and 

 inconspicuous neural spine. The first or cervical vertebra 

 (V. 1) has a very small centrum and no transverse processes. 

 There are no anterior zygapophyses, but at the junction of 

 centrum and arch there occurs on each side a large .oval 

 concave facet for articulation with one of the condyles of the 

 skull (see p. 411). The eighth vertebra has a biconcave 

 centrum; that of the ninth or sacral vertebra (V. 9) is con- 

 vex in front and presents posteriorly a double convexity 

 articulating with a double concavity on the anterior end of 

 the urostyle. 



The skull (Figs. 247, 248) consists of a narrow brain-case, 

 produced behind into great outstanding auditory capsules, 

 and in front into large olfactory capsules. The whole of the 

 bones of the upper jaw are immovably fixed to the cranium 



