HALOSAURUS RADIATUS. 299 



as the eye, five on the front of the npper portion of the first arch and ten to 

 twelve on the lower. Gill openings wide; membranes hardly united, free 

 from the isthmus. No pseudobraiichias. 



Dorsal origin two lengths of the head from the end of the snout ; base 

 equal to prenarial length of snout ;, fin highest in the anterior rays, height 

 equal rostrorbital length in head, anterior ray little shorter. Anal origin 

 three lengths of the base of the dorsal backward of the latter. Vent close 

 to the anal. Ventrals small, as long as the snout, bases little in front of a 

 vertical from the origin of the dorsal, close together, joined by membrane. 

 Pectorals small, three fifths as long as the head, above the middle of the 

 side, acuminate. Caudal section tapering to a thread-like filament. Scales 

 medium, with fine striae forming a horseshoe-shaped band parallel with the 

 hinder and the lateral edges, and on the anterior portion with longitudinal 

 strias, divergent forward from the middle of the scale ; those of the lateral 

 line no larger than the others. Lateral line descending from the upper 

 angle of the gill opening through the axil to the lower part of the side 

 whence it continues backward through a series of luminous organs. Each 

 scale of the line is transparent and bears a vertically placed organ resem- 

 bling those of Lamprogrammus, Plate XXXIV. figs. 1, 4, 5, which in turn 

 is covered by a thin transparent membrane. The number of transverse 

 series varies from two hundred and ten to two hundred and twenty-five, 

 and the number of longitudinal from eleven to twelve above the line, 

 and five below it. Mucous channels greatly developed on the side of the 

 head from the snout to the lower edge of the opercle and from the chin 

 back to the same point below each mandible. These lower canals meet the 

 others below the hind border of the orbit, but a junction is made nearer 

 the end of the tubes ; the pores open along the lower edges of the tubes. 

 Pyloric appendages ten to twelve, in a comb-like web along the intestine. 

 A specimen of thirteen and one half inches contains well developed eggs. 



Brown to blackish, the black generally in puncticulations, lighter to sil- 

 very on the sides and below ; mucous channels whitish ; tip of snout with a 

 black spot ; dorsal and pectorals lighter; fin margins black ; intestine red- 

 dish or yellowish ; linings of mouth and gill chamber, isthmus and shoulders 

 around the gill opening black ; lining of abdominal chamber silvery to 

 blackish, with puncticulations of black. A common marking on the scales is 

 silver on the middle to the anterior margin, and puucticulate brown to dark 

 brown on the posterior half of each scale. 



