1074 



SCAXmXAVIAN FISHES. 



was shown Iiy Hanxovki; to be tlie same as that of vity; and as the latter, being ])ier(e(l by tlie abdominal 



(the teeth and) the dermal spines. 



Among the peculiarities of the intei'nal organs in 

 the Elasmobranchs we liave already considered the 

 structure and position of the heart. A further charac- 



(anal) poi'es, one on each side of the anal aperture, is 

 in a cei-tain degree open to the surrounding water, this 

 element may find a passage to tlie heart itself". The 

 intestinal canal is comparatively simjile (tig. oOl). The 



ph b)\ 

 fy mpt opt pob 



Fig. 300. Skull of a Thornback {Raja clavata) seen from above {A) and from the right {B). Nafurnl size. Atter Parker. 



ehy, epihyoid; fa, foramen for the nervus facialis; fonf, frontal fontanelle; fonpf, prefrontal fontanelle; hhj, liypoliyuid; mpt, metapterygoid; 



poh, prt'orbital: sthtj, stylohyoid. The other letters are explained in fig. 298. 



teristic of these fishes is the communication afforded i wide, but sometimes very short a'Si>ijhagus ((/) passes 

 to the pericardial cavity by means of two holes behind, ' into a stomach (e) usually of greater length, and this 

 in the diaphragm, with tlie abdominal (peritoneal) ca- I termina,tes behind in a more or less prolongated blind 



" MoNRu, Striirl., PJnjsiol. Fish.. Edinburgh, 178.5, p, '20, pi. II, 22, 23, pi. .Will, 10, 11, 12. Blainviu.e, Ann. Miis. Hist. Not., 

 tome .Win (1811), p. ill. 



