402 THE ANIMAL KINGDOM. 



latter, however, they are sometimes wanting. In Urodela teeth occur on 

 the praemaxillae, maxillae, vomero-palatines, rarely on the parasphenoid, 

 as in Spelerpes rubra and Batrachoseps, and in the lower jaw on the 

 dentary and splenial. They usually form a single or nearly single row on 

 the praemaxillae, maxillae, and bones of the mandible, but the vomerine, 

 palatine, and parasphenoidal teeth are numerous and thick set. The points 

 of the teeth only just protrude above the mucous membrane. In the 

 Anura and Salamandrine Urodela they are double pointed, one point 

 external, the other internal. The bulk of the tooth consists of tubular 

 dentine surrounding a pulp-cavity, and coated with a thin layer of enamel 

 in the Frog, or capped by enamel in the Newt, &c. The teeth are affixed 

 to the jaws by pillars of true bone. In Ceratophrys (Anura) the dentine at 

 the base of the teeth is folded (as in some Lizards, e. g. Varamis). So too 

 in many Stegocephali, and in the genus Labyrinthodon the folds are deep, 

 of great extent, secondarily folded, and the intervals between them are 

 filled with cement. The Stegocephali have teeth on the praemaxillae, 

 maxillae, vomers, palatines, on the dentary, and apparently sometimes on 

 the splenial, and they are lodged in shallow depressions. The tongue is 

 rudimentary in the lower Urodela. It is wanting in the Aglossa ( = Pipa, 

 Dactylethra) among Anura, but in this order, and in Salamanders it is of 

 fair size, fleshy, attached anteriorly, but with a free thickened posterior 

 border which is thrown forward in the act of protrusion. In the Anuran 

 Rhinophrynus it is free anteriorly, and in the Urodele Spelerpes it is fungi- 

 form and can be protruded to a great distance. As in higher Vertebrata 

 the tongue has a musculature of its own ; it contains numerous glands and 

 has special sense-cells interspersed in the epithelium. The alimentary 

 canal takes a direct antero-posterior course, and the division into stomach, 

 intestine and rectum is scarcely marked externally in Proteus. It is marked 

 in other Urodela where there is a distinct pylorus, and the intestine ( = mid- 

 gut) is thrown into more or fewer coils except in Gymnophiona. The 

 rectum is dilated. The Anura are characterised by the form of the stomach, 

 which has its cardiac end dilated on the left side and its pyloric end conical 

 and contracted. The convolutions of the intestine are numerous, and lie 

 almost entirely on the right side. In the vegetable-feeding Anuran Tadpole 

 the intestine is of great length and spirally coiled. The rectum opens into 

 the anterior end of a cloaca. The mouth, pharynx, oesophagus, stomach 

 in part, and in Triton the rectum are ciliated. The intestinal epithelium 

 has a striated border and there are many glands. The liver is two lobed in 

 Urodela, elongated in the lower forms and in Gymnophiona, broader in the 

 higher. In the Anura the left lobe is subdivided into two more or less 

 completely, and in the Aglossa the three lobes thus formed are united only 

 by peritoneum. A gall bladder is always present. The pancreas is flat- 

 tened and lobed (? absent in Siren and Proteus). 



