340 
U. S. P. E. E. EXP. AND SUEVEYS—ZOOLOGY—GENEEAL EEPOET. 
TETRAODON POLITUS, Grd. 
Smooth Balloon-Fish. 
Spec. Char. —Body sub-cylindrical. Head very large, constituting the third of the length, caudal fin excluded. Pectorals 
broad, short, and rounded. Caudal posteriorly sub-convex. Skin perfectly smooth all over, the prickles remaining within the 
derm in the shape of indurated needles. Olivaceous brown above, maculated with black; yellowish and unicolor beneath. 
The head is sub-quadrangular, sub-pyramidal, larger across the thoracic region than the 
anterior portion of the body. Its upper surface is gently convex and quite declivous from the 
eyes to the snout, which is obtusely rounded off. The lips are thick and fleshy, with their 
surface papillar, the mouth being proportionally large. The eyes are rather small, sub-ellip¬ 
tical, approximating the upper surface of the scull, their longitudinal diameter entering nearly 
eight times in the length of the side of the head. 
The body from the thoracic belt tapers regularly backwards. The peduncle of the tail is com¬ 
pressed, becoming quite thin at the insertion of the caudal. The height of the dorsal fin is 
more than twice the length of its base ; its upper margin is sub-convex ; its origin is equidistant 
between the branchial apertures and the posterior margin of the caudal fin. The anal is inserted 
opposite the dorsal and somewhat further backwards ; it is nai rower than the dorsal, and nearly 
as deep as the latter is high, its inferior margin being quite convex. The caudal is posteriorly 
sub-truncated ; else broadly rounded off, and contained short of six times in the total length. 
The pectorals are very broad, rather short, posteriorly rounded off, or else convex. 
D 1, 7 ; A 1, 6 ; C 2, 1, 4, 4, 2; VO; P 15. 
The skin is perfectly smooth to the touch. The small spines or prickles which are observed 
in other species of this genus appear to remain in the present one in an undeveloped or 
embryonic condition within the skin. 
The specimen described is somewhat over twelve inches in total length. 
The upper region of the body and head is olivaceous brown, maculated with black, minutely 
and profusely dotted with black also ; the inferior region, from the middle of the flanks, being 
uniform yellowish, sometimes merging into an orange tint. The dorsal and caudal fins are 
olivaceous brown ; the pectorals and anal yellowish. 
List of specimens. 
Catal- 
No. 
Vo. of 
spec 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
983 
i 
San Diego, California.... 
1857 
A. Cassidy..... 
Alcoholic. 
A. Cassidy... 
