264 PROCEEDINGS OF THE ACADEMY OP 



The scales are moderate or rather small, cycloid, with suhcentral or slightly 

 eccentric nuclei, and with concentric striae. The lateral line runs for a short 

 distance anteriorly on the sides of the back, is then much deflected, and then 

 runs along the middle of the side to the caudal fin and is again deflected. 



The head is cuboid and nearly plane above, and covered with the smooth 

 and naked skin above as well as on the sides. The operculum is fringed be- 

 hind; the preoperculum unarmed. The suboperculum and interoperculum 

 have membranous extended borders. 



The mouth is very oblique and nearly vertical. The lower jaw closes in 

 front of the upper, and its periphery is semioval. The membranous fold be- 

 tween the limbs of the lower jaw is well developed, and conceals the front of 

 the branchiostegal membrane. 



The dorsal fin commences near the nape, and is continued nearly to the 

 caudal fin ; its rays in front are simple ; the others are articulated. 



The anal fin commences under the anterior portion of the anal fin, 

 and is also much elongated and continued nearly to the caudal. The ven- 

 tral fins are approximated, and each is composed of three simply articulated 

 rays. 



The relation of this subfamily to the Leptoscopinae has been previously ex- 

 posed. The difference consists of the presence in the Dactyloscopi of only 

 three articulated rays to the ventral fins instead of one spinous and five 

 branched as in the Leptoscopiniae. The dorsal of the latter is also as short or 

 shorter than the anal and commences some distance behind the nape ; in 

 Dactyloscopic the dorsal fin commences immediately behind the nape, and is 

 longer than the anal. The Dactyloscopinae are confined to the tropical Ame- 

 rican seas, while the Leptoscopinae are represented in the seas around the 

 islands of Australia and New Zealand. 



Genus DACTYLOSCOPUS Gill. 



Dactyloscopus Gill Proceedings of the Academy of Natural Sciences of Phila- 

 delphia, 1859, p. 132. 

 " Gill, op. cit., 1861, p. 117. 



The body is moderately elongated, its greatest height equalling about a sixth 

 or seventh of the extreme length. 



Head cuboid, oblong and nearly flat above. Eyes small and subcircular, 

 separated by a considerable space, the frontal bones being of moderate width. 



Mouth nearly vertical. Lower jaw not dilated beneath or emarginated in 

 front, and without barbels. Intralabial filament obsolete. 



Teeth villiform and only present on the jaws. 



Dorsal fin with its origin near the nape, and with its first ten or twelve rays 

 simple, and the rest articulated. Anal fin commencing under the anterior 

 part of the dorsal. 



Type. Dactyloscopus tridigitatus Gill. 



Dactyloscopus tridigitatus Gill. 



Dactyloscopus tridigitatus Gill, Proceedings Academy of Natural Sciences of 

 Philadelphia, April, 1859, p. 132. 

 The greatest height is contained 14-100 times in the Hotal length. The 

 head fr om the closed lower jaw to the end of the bony operculum forms 19-100 

 of the length ; its elevation above the inferior preopercular margin equals 

 11-19, and the height at the articulation of the lower jaw 9-19 of its length. 

 Its greatest width equals 10-19 and that behind the eyes 7-19 of the same. 

 The dorsal fin commences at the 18-100ths of distance from the snout. The 

 caudal fin forms an eighth of the total length. The pectorals equal 16-100 of 

 the same. The anterior part of the lateral line runs through eleven scales, 

 is then deflected and runs very obliquely on four scales, and is thence con- 

 tinued along the fifth row from the back through thirty. 



[Sept. 



