554 



ELEOSTEI 



CHAP. 



a 



0*0 



Fam. 9. Notopteridae. The 



Fishes which form this family 

 may be regarded as an eccentric 

 modification of a type very 

 similar to the preceding, with 

 which they agree in most osteo- 

 logical features as well as in 

 the dentition, in the connexion 

 between the air-bladder and the 

 ear, and in the absence of oviducts. 

 They differ in the absence of 

 the lid -like supratemporal, the 

 hole which it covers in Hyodon 

 being here bordered by the 

 post-frontal and the squamosal 

 (fused with the opisthotic), 

 sometimes also by the epiotic, 

 in the absence of the suboper- 

 culum, in the absence or incom- 

 plete ossification of the upper 

 branch of the post - temporal 

 (the lower articulating with the 

 opisthotic), and in the presence 

 of accessory bones (named ad- 

 pleurals) attached to or fused 

 with the distal extremity of 

 the anterior ribs, which they 

 prolong to the mid-ventral line, 

 where they are embraced by 

 dermal ossifications forming a 

 doubly serrated crest. 



The bones of the head are 

 cavernous, the mouth is large ; 

 the anterior nostril is produced 

 into a tentacle. The body is 

 very strongly compressed, with 

 very short precaudal region, 

 attenuate behind ; the ventral 

 fins are much reduced or absent ; 

 the dorsal is short or absent, 



