HELLER AND SNODGRASS 



two genera, Exonautes and Cypsilurus, each with large ventrals, this 

 species must be placed by itself in a third genus, for it differs from 

 Exonatites and Cypsilurus, as thus defined, in having short ventrals 

 and pectorals, but agrees with Exonautes in the length of the anal. 



It is probably allied to Exonautes rather than to Exoccetus, which 

 has small ventrals, on account of the posterior position of these fins, 

 the ventrals being anterior in Exoccetus. Evolantia, hence, repre- 

 sents an Exonautes with unspecialized ventrals and with but slightly 

 elongated pectorals. 



Specimens were secured in latitude 4 N., longitude 90 W. 



SPHYR^ENA IDIASTES sp. nov. 

 pi. ii. 



Type. Cat. No. 12331, Leland Stanford Jr. University Museum. 

 Seymour Island. 



Diagnosis. Differs from 6 1 . argentea, its closest American ally, 

 in the posterior insertion of the ventrals, the greater length of the head, 

 the wider interval between the maxillary and eye and in the possession 

 of smaller scales. It is apparently most closely related to S. heller 7* 1 of 

 the Hawaiian Islands from which species it differs in the scale formulae, 

 in the greater number of vertical rows of scales on the opercle, in the 

 extension of the scaled area beyond the posterior border of the eye and 

 in the longer pectorals. 



Description of the Type. Length 480 mm.; head 3; depth 8; 

 eye 7; D. V, 10; A. 10 ; scales 20-145-12. 



General shape fusiform, dorsal and ventral outlines symmetrical ; 

 head slender, acutely conical. Maxillary not reaching anterior border 

 of orbit, separated by a space a little greater than diameter of eye ; 

 suborbital one half of head ; posterior angle of opercle obtuse ; exserted 

 portion of mandible slightly greater in length than one half diameter 

 of eye. Scales on suborbital, extending forward to below center of 

 pupil ; top of head, sides of snout and a crescent-shaped area behind 

 and below eye naked. 



Front of each jaw toothless ; a series of small, flat, triangular teeth 

 along sides of both jaws; those on mandible larger and fewer. 

 Internal horizontal plate of each premaxillary with three large, flat, 

 elongate teeth inclined backward ; in line with each of these series are 

 a series of six similar, large, palatine teeth directed downward and in- 

 ward followed by a long series of minute teeth. Anterior portion of 

 mandible with two large, triangular teeth directed backward. 



^Sphyrcena helleri Jenkins, Bull. U. S. Fish Comm., p. 387, 1899. 



