NOTOPTEKID.E. 



79 



NOTOPTERID^E. 



Margin of the upper jaw formed by the praemaxillaries and the maxillaries, the latter 

 the more developed ; parietal bones separating the supraoccipital from the frontals ; a 

 large hole on each side of the skull, between the squamosal, the exoccipital, and the 

 epiotic ; symplectic present ; no suboperculum ; interoperculum small, hidden under 

 the prseoperculum *. No pharyngeal teeth. Ribs sessile ; accessory bones (adpleurals) 

 attached to the extremity of the anterior ribs, with which they may be fused, and 

 embraced by ossifications forming a double ventral serrature ; prsecaudal vertebrae with 

 transverse processes in front of the ribs. Pectoral fins folding against the body. 

 Air-bladder communicating with the ear. No oviducts. 



rk. 11. 



Skeleton, with outline of soft parts, of JVotojjterus afer. (From ' Cambridge Natural History.') 



The bones of the head are cavernous ; the mouth is large, and the maxillary bone is 

 toothed as well as the prsemaxillary. 



The body is very strongly compressed, with very short prsecaudal region, attenuate 

 behind ; the ventral fins are much reduced or absent ; the dorsal fin is short or absent, 

 and the anal is much elongate and confluent with the caudal, which may be regarded 

 as aborted, having lost the hypural bone, which in homocercal fishes supports the 

 caudal rays. The air-bladder is very large, with several divisions, forked in front and 

 behind f . 



* On the structure of the skull, cf. Eidewood, Journ. Linn. Soc, Zool. xxix. 1904, p. 202. 

 t Of. Bridge, Journ. Linn. Soc, Zool. xxvii. 1900, p. 503. 



