280 



ZOOLOGY 



SECT. 



(Pt), and the palatine, when distinct, bears teeth. The sus- 

 pensorium is inclined forwards, as in the Tadpole, not back- 

 wards as in the adult Frog. The hyoid arch is large, and 

 its dorsal end may be separated as a hyomandibular. There 

 are three or four branchial arches which are large in the perenni- 

 branchiate forms, but undergo more or less reduction in caducibranch 

 species, never, however, forming such a simple tongue-bone as that 

 of the Frog. The stapes has no columella attached to it, and in 

 correspondence with this there is no tympanic cavity or membrane 



J2T 



FIG. 893. Salamandra atra. The skull. A, from above ; B, from below. In both the 

 membrane bones are removed on the right side of the figure. Af, antorbital process ; As, 

 alisphenoid ; Bp, basal plate ; Can, nasal cavity ; Oh. posterior nares ; Ci, process of internasal 

 plate ; Cocc. occipital condyles ; J). aperture of lacrymal duct ; F. frontal ; Fl, olfactory fora- 

 men ; For. fenestra ovalis ; IN. internasal plate ; L/jt. ligament connecting stapes with sus- 

 pensorium ; M. maxilla ; .A", nasal ; Na. nasal aperture ; NK, olfactory capsule ; OB, auditory 

 capsule ; OS, spheiiethmoid ; Osp, supra-occipital region ; P, parietal ; Pa, ascending process of 

 suspensorium ; ped. pedicle ; Pf. pre-frontal ; Pmx. pre-maxilla ; Pot. otic process of suspensor- 

 ium ; Pp. palatine process of maxilla ; Ps. parasphenoid ; Pt. pterygoid bones ; Ptc. pterygoid 

 cartilage ; Rt, foramen for nasal branch of trigeminal ; Qu. quadrate ; Squ. squampsal ; St. 

 Vo. vomer ; Vop. vomero-palatine ; Z, process of internasal plate ; V, trigeminal 



stape 

 foramei 



VII, facial foramen. (From Wiedersheim's Comparative An<i/<n,<i/.) 



In the Anura there is a very wide range of variation in the 

 skull. Among the most important points are the presence, in a 

 few species, of small supra- and basi-occipitals, and the fact that in 

 others the roofing membrane-bones are curiously sculptured and so 

 .strongly developed as to give the skull a singularly robust ap- 

 pearance. 



In the Gymnophiona (Fig. 894) very little of the original car- 

 tilage remains in the adult state, but the membrane bones are 

 very large and form an extremely complete and substantial 

 structure, especially remarkable for the way in which the small 



