CHORDATA 



301 



the same is true of the pectoral and pelvic girdles, composed oi 

 bones to which the appendicular skeleton is attached; thi 

 girdles are more or less intimately connected with the axial 

 skeleton. The skull and vertebral column are bony, but the 

 ribs are very rudimentary (Fig. 308). 



All of the Amphibia are provided with gills, three pairs oi 

 soft processes or outgrowths of the integument rich in blood 

 vessels and known as the external gills, such as occur in some 



SPHE T H 



PMX 



M.MCK 



Fig. 309. Rana temporaria. Dissection from the left side; the viscera somewhat displaced. 

 an, amis; fi.d, bile duet; b.hy, body of hyoid; bl, urinary bladder; bl' , its opening into 

 cloaca; cart, cornus arteriosus; cblm, cerebellum; cl, cloaca; cn.j, centrum of third 

 vertebra; cp.ad, corpus adiposum ; crb.h, cerebral hemisphere; d.ly.sr, dorsal lymph sinus; 

 du, duodenum ; epxor, epicoracoid; ens./, Eustachian tube; FA'./'. I, fronto-parietal ; gl, 

 glottis; gul, gullet or oesophagus; IL, ilium; IS, ischium; kd, kidney; I. an, left auricle; 

 l.lng, left lung; //-, liver; M.MCK, mento-meckelian ; n.a.i, neural arch of first vertebra; 

 • '//./, olfactory lobe; opt/, optic lobe; O.ST, omo- and epi-sternum ; ped, pericardium ; 

 PMX, premaxilla ; pn, pancreas ; p.i/a, posterior naris ; pu , pubis ; ret, rectum ; r.lng, right 

 lung; s.mt, small intestine; sp.cd, spinal cord ; SPH.ETH, sphenethmoid ; spt, spleen; st, 

 stomach; s.v, sinus venosus; tng, tongue; ts, testis; ur, ureter; ur' , its opening into the 

 cloaca; UST, urostyle; v, ventricle; v.fy.s, ventral lymph sinus; vet, vomerine teetli ; 

 : tla seminalis. (After Parker and Haswell.) 



fishes, but only in the embryonic condition for the most part. 

 In some cases these gills persist throughout life, but in the 

 majority they disappear, and respiration is then carried on 

 by means of lungs as in the higher Vertebrata. Some Am- 

 phibia have neither gills nor lungs, and in these respiration 

 takes place through the skin and through the wall of the 

 pharynx, which in such cases is provided with numerous blood 

 vessels. The direct respiration of air is accompanied b; 



