STERNOin'YX ORSCURA. 233 



parts of which the left (in this extunplo) is the more forward ; both parts hook- 

 in"- backward shghtly. Opercuhir margins membranous. Gills four. Pseudo- 

 branchiie present. Five ridges across the flank. The compressed blade-like 

 spine at the origin of the dorsal is serrate, with about twenty-five teeth. 

 The ventral spine has four cusps, the anterior pair longer and directed for- 

 ward, the posterior pointing down. The anal spine is forked, and inclines 

 forward and downward. The greatest convexity in the dorsal outline 

 of the body lies under the dorsal fin. The angular diaphanous space for- 

 ward of the anal is very little wider than a right angle. 



The luminous facets, lanterns, on each side are distributed thus : three 

 small ones at the lower edge of a wart-like prominence a little above the 

 base of the pectoral; one behind the angle of the mouth, and apparently 

 another a short distance above; four or five in each branchiostegal series; 

 ten large ones in the close series from the humeral spine to the ventral; 

 three in the abdominal series; three in the anal group; three or four in the 

 subcaudal group ; and three on the flank a short distance above the vent. 



Upper portions clouded brown or blackish ; flanks and lower surfaces 

 silvery ; lanterns silvery, edged with black. The luminous organs are in 

 function downward ; that is, forward when the creature is swimming and 

 feeding. The lower (anterior) fourth of the iris is silvery, as also is a patch 

 on the cheek below the eye. The silver area below the orbit contains indi- 

 cations of a lantern ; po.ssibly rudimentary, but useful in estimating the 

 affinities of the genus. 



This species is readily distinguished from S. diajj/miia by the difference 

 in form. 



