582 



GIIOUDATA. 



(dentary, splenial, angulare, etc.); its articular portion, like the 

 quadrate, being rarely incompletely ossified. A^omers, palatines, 

 and pterygoids appear in the base of the skull, all three forming a 

 continuous arch in the Auura; in front of them lie the premaxil- 



_ '' /'-f JT 



rin pmr 



Fig. 612 —Lateral and hinder views uf frog skull. (After Parker.) Letters for this 

 and 611 ■ nil, angulare ; ^-l.S alisphenoid cartilage; co (Cecc), occipital condyles; 

 coi, columella; ((, dentary ; i' (e), sphenethmoid; fo, foramen magnum; ¥P, 

 frontoparietal; Gfe, otic capsule; h',h", hyoid and copula; jg, jugal; M (m), 

 maxillary (in lower jaw mento-Meckelian) ; mk, Meckel's cartilage; IV", J\ ', 

 nasal capsule; aa, nasal; nli, o.s, cartilages from which basi- and supraoocipitals 

 arise elsewhere ; nliOlaf), exocoipital ; pr, frontoparietal; Pdi, palatine ; p (PP), 

 palatine arch; Pmx, premaxillary ; P;-o, prootic; Ps, parasphenoid: Pt. pterygoid; 

 (>»i(, quadrate; C^iji;, jugal; si/, squamosal; I'j, vomer. Cartilages dotted. 



laries, and in most cases maxillaries. Between the hinder end of 

 the maxillaries and the quadrate there may be a gap or it may be 

 bridged by a jugal. By the modification of the quadrate into a 

 , suspensor the hyomandibular loses 



its function, and if represented at 

 all, it is as part of the columella. 

 The character of the remaining vis- 

 ceral skeleton dejjends upon the 

 respiration (fig. 613). Where gills 

 occur, the copula and hyoids — repre- 

 FiG. 613.— Hinder visceral skeleton of sentiug bodv and coruua — as well as 



iA) larva of a salamander ; {B) of „ ... C i ■ i 



toad. (From Gegenbaur.) ((, hody lour gill arches are present, but with 



of hyoid; ?>, anterior horn (livoid); ^ . ,. i t .n 



c, rest of branchial skeleton. pulmonary respiration the liyoia ap- 



paratus is reduced to a hyoid with anterior and posterior cornua, 

 the gill arches being contained in the posterior horns. 



With the assump)tion of a terrestrial life changes occur in the 

 sense (irgans. The organs of the lateral line, which occur in all 

 larvaa and are piersistcnt in the aquatic perennibranchs, and the 

 nerves which supply them, disappear; the eyes in the Salamandrina 

 have upper and lower lids; in the frogs an under lid (raally nicti- 

 tating memln-ane). The nose becomes respiratory and is provided 

 with choanai opening into the mouth. Especially noteworthy is 

 the auditory appiaratus. This, in the urodeles and Cfecilians, is 



