Classification of the Bleu nioi'd Fishes. 279 



ankylosis of the pteryo'oicl and meso|,'terygoicl, and the 

 juolongation forwards of the cleithra within the isthmus as 

 a [)air of slender processes, with the pelvic bones attached at 

 tlieir extremities. The lower fork of the post-temporal is 

 shortened and attached to the opisthotic by a ligament, and 

 the coracoids are in contact. There are 72 vertebra? (20 + 52) : 

 the first five are as in Brotula, except that oidy the first rib 

 is expanded; the anterior six pairs of parapopliyses (on 

 vertebra? G-11) are strong and broad, much as in Merluccius, 

 the rest are normal. 



Principal genera : Ophidium, Otophid'ium, Lepophidiumy 

 G<ni/pterusj from tropical and temperate seas, some in- 

 habiting deep water. 



Derej odic/ithijs, Gilbert, from the North Pacific, has the 

 mouth non-protractile, the body naked, and the gill-openings 

 more restricted than the others ; it may not pertain to this 

 faujily and may prove to be related to the Zoaicida?. 



Family 3. Fierasferidae. 



Differ externally from the Brotulidpe in that the anal fin 

 extends further forward and the vent is placed at the throat, 

 caudal and pelvic fins are absent"^, and the mouth is non- 

 protractile. The craniu n shows many striking resemblances 

 to that of Biotula, but differs in that the parietals meet above 

 the supraoccipital, the occipital crest is weak, and the ex., 

 occij itals do not take part in its formation, and the enlarged 

 opisthotic reaches the basicccipital, sharing with that bone 

 and the pro-otic in the formation of the auditory bulla f. 

 The low^er fork of the |X)st-temporal is reduced to a little 

 knob; otherwise the pectoral arch is as in Genypterus. In 

 Fierosfer oxus [fide Emery) the vertebrae rmmber 125 to 144, 

 of which 17 or 18 are pracaudal ; in F. dentatus there are 26 

 pijecaudal vertebrse; the first rib is more strongly expanded 

 in the former species than in the latter. 



Seeing that tiie Fierasferidae had always been placed near 

 the OpI idiida3, and that Emery's anatoiuical researches con- 

 firmed this view as to their systematic position, it is not 



* I at one time thouglit tliat a reduced homocercal fin was present in 

 some Fiei'a>feridte, as iu the lirotulidse ; but on looldng- into the matter 

 I tind that whenever a caudal fin appears to be present it is due to 

 regeneration after the end of the tail has been broken off. 



t 'I'hese features were first described by Emery (Faun. u. Flora d. 

 Golf. V. Neap. ii. 1880), and I am able to confirm' the accuracy of his 

 account of the head-skeleton, after preparing and examining that of 

 F. acus. 



