366 
U. S. P. R. R. EXP, AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
fins are more developed, although alike in shape. The anterior margin of the first dorsal is 
somewhat nearer the extremity of the snout than the anterior margin of the second dorsal, which 
is nearly equidistant between the tip of the caudal fin and the orbit. The origin of the anal fin 
is nearly equidistant between the tip of the caudal and the posterior end of the insertion of the 
pectorals ; its posterior extremity reaches the anterior margin of the first portion of the lower 
lobe of the caudal, and which we should he inclined to consider as a second anal fin. The origin 
of either lobe of the caudal fin is almost even; the inferior lobe is much deeper anteriorly than 
the upper. The posterior portion of the lower lobe of the caudal is much smaller than the 
anterior portion. It is exteriorly rounded or sub-truncated, and separated from the upper lobe 
by a small incision, which corresponds to the tip of the vertebral column. The posterior margin 
of the ventrals, which is sub-truncated or sub-concave, extends somewhat beyond the origin of 
the second dorsal. The posterior edge of the pectorals is sub-convex or rounded off; its middle 
region approximating the origin of the ventrals when bent in that direction. The vent is lon¬ 
gitudinal, and placed between the ventral fins. 
The upper surface of the body and fins is very rough to the touch; the scales, or rather dermic 
productions, are very small, and irregular in size and shape. They are more conspicuous over 
the supra-ocular ridges and the dorsal region, properly so called, where some of them are raised 
above the others ; they are smallest over the fins and sides of the body; hut whether triangular, 
sub-rhombic, or cruciform, the angles are always acerated, the points being sometimes a con¬ 
tinuation of a minute keel, which start from the middle of the scales. Over the inferior surface 
of the head, body and horizontal fins, the scales are sub-rhombic or sub-cordiform, likewise 
variable in size, exhibiting hut one single inconspicuous keel, without angular points; hence 
that surface assumes quite a smooth aspect. The scales, moreover, are closely approximated, 
sub-imbricated, whilst on the upper surface of the body they are almost all isolated. The 
color above is yellowish grey, darker in the young; beneath light yellow. Small roundish, 
black spots, are spread all over the body and fins. 
List of specimens. 
Catal. 
No. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
993 
2 
Adult. 
Bay of Monterey, Cal. 
1853 
Lt W. P. Trowbridge .. 
Alcoholic .. 
Lieut. Trowbridge.... 
Family NOT ! DA X IDAE, Owen. 
The head is flat or depressed. The nostrils are provided with a small, triangular flap. A 
very large fold or wrinkle at the upper (anterior) angle of the mouth ; a smaller one at the 
lower (posterior) angle ; nictitating membrane wanting ; tongue immovable. The spiracles 
are small and vertical. The branchial apertures are six or seven in number, diminishing gradu¬ 
ally in size from forwards backwards, all of which are placed in advance of the base of the pec¬ 
toral fins. A tooth at the symphysis of the lower jaw ; the next five or six teeth on the lower 
jaw constitute on either side a saw, directed from upwards and inwards, downwards and out¬ 
wards. The anterior or inner edge of the teeth is smooth or very finely serrated. The outer¬ 
most teeth of the jaw are low and depressed. The teeth at the upper jaw are more elongated, 
smaller and more acute ; the first prong or point is much longer than the rest ; their outer 
