HALOSAURUS RADIATUS. 299 
as the eye, five on the front of the upper portion of the first arch and ten to 
twelve on the lower. Gill openings wide; membranes hardly united, free 
from the isthmus. No pseudobranchie. 
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. Candal section tapering to a thread-like filament. Scales 
medium, with fine strize forming a horseshoe-shaped band parallel with the 
hinder and the lateral edges, and on the anterior portion with longitudinal 
strie, 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 puncticulate brown to dark 
brown on the posterior half of each scale. 
