554 ELEOSTEI CHAP. 
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-lke 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, 
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