FISHES—GASTEROSTEIDAE—GASTEROSTEUS WILLIAMSONI. 
98 
Oregon. In its general appearance it resembles G. microcephalus most, and what has just been 
stated in regard to the latter, with reference to G. quadracus, applies equally to it. 
It is much to our regret that the state of keeping of the specimens will not permit a thorough 
description of the soft fins. The species differs from G. microcephalus by a larger head, much 
smaller spines, and fewer plates upon the thoracic region. The head enters three times and a 
half in the total length ; the eyes are circular and very large, since their diameter enters but a 
little over three times in the length of the sides of the head, and not quite once in advance of 
the anterior rim of the orbit. The dorsal spines ar.e slender, acute, and smooth upon their 
edges ; the anterior one is inserted immediately behind a vertical line drawn across the base of 
the pectorals. In being brought horizontally backwards, its extremity would hardly reach the 
second dorsal spine; the latter, at any rate, remains considerably behind the third in that 
respect. The origin of the second dorsal is even with a vertical line passing by the extremity 
of the ossa innominata. The insertion of the ventrals is entirely in advance of the second dorsal 
spine ; their spine exhibits a very slight serrature upon its edges, and its extremity extends 
beyond the tips of the ossa innominata. 
The plates or shields are hut four in number, occupying the space between the first and second 
dorsal spines. The three longest converge towards the vertical process of the ossa innominata. 
The ground color is brownish, rather dark along the dorsal region; the sides are transversely 
barred with black, the bars or bands being composed of crowded dots. The belly is unicolor. 
The largest specimens measure an inch and a quarter. 
List of specimens. 
Catalogue number. 
| No. of specimens. 
Locality. 
When collected. 
Whence obtained. 
Nature of specimens. 
Collected by— 
339 
6 
Fort Steilacoom, Puget’s Sound 
1853 
Gov. 1.1. Stevens__ 
Alcoholic. 
Dr. Suckley_ 
T. GASTEROSTEUS WILLIAMSONI, Grd. 
Spec. Char. —Body smooth all over ; peduncle of tail not keeled. Dorsal spines three, exiguous and slender, and not serrated ; 
insertion of anterior one situated above the base of the pectorals. Insertion of ventrals slightly in advance of the second dorsal 
spine ; their own spines are serrated upon both edges, and their extremities do not reach the tips of the ossa innominata. Posterior 
margin of caudal fin sub-crescentic. 
Syn. — Gasterosteous williamsoni, Grd. Proc. Acad. Nat. Sc. Philad. VII, 1854, 133. 
This is the most slender, and, consequently, the most elongated and graceful of all the species 
of the genus above described. The body is sub-fusiform in profile, and, as usual, compressed. 
The greatest depth, taken across the base of the pectorals, is a little more than the fifth of the 
total length. The upper surface and the sides of the head are corrugated, the head itself 
forming the third of the total length, the caudal fin excluded. The eyes are large and circular, 
and their diameter is contained three times and a half in the length of the sides of the head. 
The mouth is slightly oblique and the lower jaw longer than the upper, the free extremity 
of the maxillary extending to a vertical line intersecting the nostril. 
