FAMILY TRIGLIDJE — GASTEROSTEUS. 67 



This species is very closely allied to the preceding, and resembles, as Cuvier has observed, 

 the G. tracKurus, or common Three-spined Stickleback of Europe. I have noticed them 

 frequently thrown ashore on the beach of the ocean, completely exenterated, but their bony 

 cuirass preserving their form entire. 



THE FOUR-SPINED STICKLEBACK. 



GaSTEROSTEUS aCADRACUS. 



PLATE VI. FIG. 18. — (STATE COLLECTION.) " 



Gasterosteus juadrams. MiTCHILL, Tr. Lit. and Phil. Soc. Vol. 1, p. 430, pi. 1, fig, 11. (Bad.) 

 G. id. et apeltes. Cvv. et Val. Hist, des Poiss. Vol. 4, p. 505. 

 <?. apeltes, Bloody Stickleback? Stoeer, Mass. Report, p. 31. 



Characteristics. Olive-green, marbled with dusky. Sides not cuirassed. Three or four spines 

 before the dorsal. Length one or two inches. 



Description. Body compressed, highest opposite the first dorsal spine ; back arched. Tail 

 exceedingly slender. Head small, descending. In front of the dorsal fin are three and occa- 

 sionally four moveable spines, with a small membrane attached to each, all lying in a groove ; 

 the first longest, the others successively shorter. The dorsal fin commences a short distance 

 behind the spines, with one contiguous spine and twelve articulated rays ; the anterior soft 

 rays are largest; the whole fin is received into a groove. Pectorals feeble, and composed of 

 twelve slender rays. Ventrals reduced on each side to a single stout triangular spine, ser- 

 rated on its anterior edge. The os innominatum beneath is elongated on each side, above the 

 spiny ventral, until it reaches the vent : these are " the lateral spines " of Mitchill. Anal fin 

 with an acute recurved spine, and ten soft rays. Caudal fin emarginate, with thirteen rays. 



Color. Silvery plumbeous above ; whitish beneath, often marbled with dusky on an olive- 

 green ground. 



Length, 1-0- 2-0. 



Fin rays, D. 3 or 4.1.12; P. 12; V, 1 ; A. 1.10; C. 13. 



This species abounds in our waters. Cuvier and Valenciennes describe the apeltes as a 

 species " qui pourrait bien etre celle que M. Mitchill a eue sous les yeux, quoiqu'elle reponde 

 " assez mal a sa description." Dr. Storer describes a membrane attached to the ventral 

 spine, which escaped my notice. A typographical error in that gentleman's description^ 

 makes him attribute but five rays to the dorsal fin. 



In a monography of Gasterosteus, or in a general Systema, it will be found necessary to 

 consider this species as the type of a new genus, including perhaps concinnus, for which the 

 name of Apeltes would be sufiiciently characteristic. 



