304 



ZOOLOGY 



SECT. 



FIG. 952. Pelvic girdle of Salamandra. a, b, 

 processes of epipubis ; Ep. epipubis ; Fo. ob- 

 turator foramen ; G. acetabuluru ; U. ilium ; 

 /x. ischium ; P. pubis ; Sy. pubo-ischiatic syrn- 

 physis ; *, processes of pubis present in some 

 Urodeles. (From Wiedersheim.) 



the epipubis (Ep). It is developed independently of the pelvis, and 

 its relations to that structure are very similar to those of the 



sternum to the shoulder-girdle; 

 it has, in fact, been proposed 

 to call it a pelvi-sternum. 



The limbs of Urodela differ 

 from the typical structure 

 already described only in de- 

 tails : there are usually four 

 digits in the fore-limb and 

 five in the hind-limb. In 

 Anura the limbs are modified 

 by the fusion of the radius 

 and ulna and of the tibia and 

 fibula, arid by the great 

 elongation of the two proximal 

 tarsals. A prehallux is fre- 

 quently present. 



Myology. In the lowei 

 Urodela the muscles of th< 

 trunk and tail occur in th< 

 form of typical myomeres like 

 those of Fishes. In the 



higher forms the myomeres become converted into longitudinal 

 dorsal bands the extensors of the back, paired ventral bands th< 

 recti abdominis, and a double layer of oblique muscles, covering tin 

 flanks. 



Digestive Organs. The teeth are always small and ankylosed 

 to the bones : they may be singly or doubly pointed. They occur 

 most commonly on the premaxilla?, maxillae, and vomers, but may 

 also be developed on the dentaries, palatines, and, in one instance, 

 on the parasphenoid. In many Anura, such as the Common 

 Toad, teeth are altogether absent. In some of the Stegocephala, 

 such as Mastodonsaurus, the teeth are extraordinarily complex in 

 structure, the tissues being folded in such a way as to produce in 

 section a complex tree-like pattern. It is from this circumstance 

 that the term Labyrinthodont, often applied to the Stegocephala, is 

 derived. 



The enteric caned is divisible into buccal cavity, pharynx, gullet 

 stomach, small intestine, rectum, and cloaca. ' The stomach am 

 duodenum together form a U-shaped loop in which the pancreas 

 lies. The tongue in many Urodeles is fixed and immovable, like 

 that of a Fish : in most Anura it is free behind, as in the Frog 

 but in Xenopus arid Pipa (hence called Aglossa) it is absent. 



Respiratory Organs. With very few exceptions Amphibia 

 possess external gills in the larval state, and, in the perenni 

 branchiate Urodela, these organs are retained throughout life 



