FAMILY TEIGLIDJS — GASTEROSTEUS. 67 



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

 the G. trachurus, 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. 



GaSTEBOSTEUS aCADRACUS. 



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



Gastmateta quadrams. MiTOHILL, Tr. Lit. and Phil. Soe. Vol. 1, p. 430, pi. 1, fig, 11. (Bad.) 1^ 



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

 G. apeltes, Bloody Slickleback? Stoeee, 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, TO- 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 k 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 sufficiently characteristic. 



