FISHES GASTEROSTEIDAE — GASTEROSTEUS PLEBEIUS. 



87 



the seventh of the total length, is composed of ten bifurcated and two undivided rays, together 

 with several rudiments above and below. The anal has the same general outline as the second 

 dorsal, but is much shorter, since its origin is opposite the fifth ray of the fin just mentioned, 

 and extends no further posteriorly ; the posterior rays of both being perfectly even. Composed 

 of nine or ten rays, the middle ones are likewise bifurcated upon their extremity. It is pre- 

 ceded anteriorly by a small spine^ similar to that at the anterior margin of the second dorsal. 

 The insertion of the ventral spine is situated in advance of a vertical line drawn anteriorly to 

 the second dorsal spine ; it is acerated, conspicuously serrated, or prickly upon both edges, and, 

 when bent backwards, its extremity does not extend as far as the tips of the ossa innominata. 

 A minute, soft, and undivided ray, may be observed within the membrane at the inner surface of 

 the spine. The base of the pectorals, with reference to the first dorsal spine, has already been 

 alluded to. These fins are broad, rather short and rounded exteriorly ; they are composed of 

 ten undivided rays, with an interradial membrane even with their tips. 



Br. Ill : III ; D I, I, I, 13 ; A I, 10 ; C 3, 1, 5, 5, 1, 2 ; V I, 1 ; P 10. 



The anterior portion of the body, from the scapular region to the second dorsal spine — that 

 is, the thoracic region — is covered with bony plates, or scutellas, transversely elongated. The 

 three anterior, or supra-scapulars, are quite reduced, but the four succeeding ones occupy all 

 the space between the dorsal plates and the ventral shields ; the last of the four just referred to, 

 situated posteriorly to the second dorsal spine, does not reach the ventral line ; the cubital pro- 

 cess, ascending from the ossa innominata, overlaps the extremities of the three remaining ones. 

 The rest of the body is covered by a smooth skin. 



The ground color of the upper region is light brown, and silvery white beneath, sometimes 

 of a dull appearance when the slimy mucous is still adherent. The upper surface and part of 

 the sides of the head is maculated with blackish or brownish. The back and sides are likewise 

 blotched, sometimes irregularly, oitentimes disposed in transverse bands or fascije, which^ upon 

 a minute examination, are found to consist of crowded dots. The fins are all unicolor, yel- 

 lowish or olivaceous brown. 



Specimens were obtained from the salt marshes about Presidio, near San Francisco, California, 

 by Lieutenant W. P. Trowbridge and hr. John S. Newberry. 



We have observed other specimens, a little stouter than the preceding, with the serratures 

 of both the ventral and dorsal spines less conspicuously developed, and occasionally with one 

 thoracic plate less, and which were procured at San Jose, California, by A. G. Grayson, Esq., 

 and at Petaluma, Sonoma county, California, by E. Samuels. 



List of specimens. 



