240 



FISHES 



articulated to each of its outer extremities the basal cartilage 



(metapterygium) of the pelvic 

 fin. Sometimes there is a rudi- 

 ment of a dorsally-directed " iliac " 

 process at each extremity of the 

 girdle, but in no Fish do these 

 processes ever acquire a dorsal 

 connexion with the vertebral 

 column. In the Holocephali the 

 iliac processes are better developed 

 than in any other Fishes, but 

 ventrally the lateral halves of the 

 girdle are united by ligament 

 alone. In the Teleostomi im- 

 portant differences are observable 



FIG. 142. The left half of the pelvic in foth girdles. The .primary 



girdle arid the right pelvic fin of . - 1 



Ghiloscyllum. meta, Metapterygium ; Cartilaginous pectoral girdle nOW 



^pelvic girdle. (From Parker and cons i stg o f distinct lateral halves 

 Haswell.) 



which have no ventral connexion 



with each other. In addition, there is developed on the outer 

 surface of each half a series of membrane bones, which form 



Flo. 143. Left half of 

 the pectoral girdle of 

 a Trout (Salmofario), 

 seen from the inner 

 surface. CL, Clavicle 

 (cleithrum) ; COR, 

 coracoid ; D.F.R, 

 dermal fin -rays ; 

 MS. COR, meso-cora- 

 coid ; P. CL, P. CL' , 

 post-clavicles ; 

 PTG.l, proximal; 

 ptg.'2, distal pterygio- 

 phores ; P.TM, 

 post-temporal; S.CL, 

 supra-clavicle ; SCP, 

 scapula. (From 

 Parker and Haswell.) 



a secondary girdle (Fig. 143). From above downward the series 

 includes a supraclavicle and a cleithrum (clavicle of Teleosts) 

 which are always present, and to these may be added in the 



