232 DEEP SEA FISHES. 



Close relationship is evident between the species of the central eastern 

 Pacific and those of the central western Atlantic, but they can hardly be said 

 to be closer than such as exists between the former and species of other 

 localities in the northern or the western parts of the Pacific. 



The eight species of the family represented in the present collection all 

 appear to be more or less distinct from what have previously been described. 

 Besides these, several others used in comparisons have also been described. 

 The fixct that the species in the collection differ so much from those hereto- 

 fore known suggests that, though they might be expected to drift readily 

 ■with the ocean currents, there is actually less of horizontal migration than 

 was expected. 



The resemblance between the very 3'oung Argyropelecus and the adult 

 of Valenciennellus or Maurolicus indicates that the ancestral form of the 

 first was approximately the present form of the last. The new genus Lych- 

 nopoles differs from Gonostoma mainly in possessing several additional rows 

 of luminous organs on each flank. It might perhaps be better placed if the 

 generic diagnosis of the latter were so modified as to admit it as a subgenus. 

 Opisthoproctus has been placed in the family by others ; it is left there 

 until a better place is found for it. 



STERNOPTYCHID.E. 



Sternoptyx obscura sp. n. 



Plate LIII. fig. 1. 



Br. r. 5; D. 10; A. 13; V. 5; P. 10. 



Body longer, less deep, and less oblique than that of S. diaphana, greatest 

 depth about two thirds of the entire length without the caudal. Length of 

 the head three fifths of its depth, four ninths of the depth of the body, or 

 less than one third of the length fi-om the snout to the base of the caudal, 

 with a longitudinal groove on the forehead between two keels. Eye large, 

 nearly half as long as the head. Mouth wide, nearly vertical; maxillary 

 narrow, as long as the eye. Teeth very small, in narrow bands. Chin 

 short, vertical. Tongue broad, slightly notched at its end. A short sharp 

 spine below the angular ; another below the preopercle ; two above the 

 occiput; and two more above the shoulders. A short strong spine below 

 the front end of the humeral symphysis ; below, the chin is formed of two 



