THE DOGFISH 



349 



Limbs. 



.. rod. 



•ft. r. 



as basalia and are attached to the neural and haemal spines. They are 

 succeeded by a similar series known as radialia, and these by two rows 

 of small, polygonal plates of cartilage which support a final series of 

 horny rays or actinotrichia. In the caudal fin the cartilaginous rays are 

 not distinct from the neural and haemal spines. 



The limbs are anchored into the body by girdles which 

 correspond to 



those iscpu. 



of the 

 frog. The pec- 

 toral girdle con- 

 sists of two 

 curved pieces of 

 cartilage, at the 

 sides of the body, 

 of which the 

 lower ends are 

 fused in the mid- 

 ventral line. To 

 the hinder sides 

 of these pieces 

 are articulated 

 the fins. The 

 surface of articu- 

 lation is the 

 glenoid facet, the 

 portion of the 

 girdle above the 

 facet being the 

 scapular region 

 and that below 

 the coracoid. The 



scapula is rod-like; the coracoid is broad and fiat and 

 supports the floor of the pericardium. The pectoral fin 

 articulates with its girdle by three basal cartilages, the pro-, 

 meso-, and metapterygia, of which the former is the anterior 

 and smallest, the metapterygium the hinder and largest. 

 Along the outer borders of these pieces are set a series of 

 radialia. The pro- and mesopterygia each bear one stout 

 ray, the metapterygium several, which are slender. To the 

 end of these, smaller, polygonal pieces are attached, and to 



Fig. 250. — The skeleton of the pelvic fins and 

 girdle of a female dogfish. 



x., Acetabular surface; Irp., basipterygium ; k.r., horny 

 rays ; //., iliac process ; iscpu., ischio-pubic region ; 

 rod. , cartilaginous rays. 



