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 vertebra; 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 proca'lous. Each half of the neural arch 

 consists of two parts, — a pillar-like pedicle (pd) 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 (tr. 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 



