HISTORT OF THE FISHES OF MASSACHUSETTS. 43 



Gasterosteus Dekayi, Agassiz. 

 The Jlafiy-spified SiicMebach 



(Plate YIII. Fur. 5.) 



Giistcrostais pungltlii^, Ten-'ipihed ^ticlckl tick Siorer Heport p. »32. 



Gaslcwsinis occidcntaiis Ma7iy-spi?icd Stitlhback Dlkvi, Ileport, p. 6S, pi 42, fiG*. 103. 



Stof.liIj Mem. Amer. Acad., Xew Series, ri. p III "j. 

 "■ " " '- STOitJDE, Synopsis, p. 63. 



Gasterosteus DeJcaiji\ AcrASSiz. Lake Superior, p. 311. 



Color. When alive, this fish is of a grayish-yellow color, witli from six to ten 

 transverse dark bands upon its sides, which are very distinct in some specimens, while 

 in others they are scarcely visible. In the same individual, these bands are inoch more 

 apparent at some moments than at others, as the jSsh is excited by fear or other causes. 

 The opercula and abdomen are silvery. Pupils black; irides metaOic. After death the 

 color of the fish is much lighter, and the bands, in a great measure, disappear. 



Description, Body much elongated. Greatest depth of the fish rather more than 

 one eighth of its length. Length of the head one fifth the length of the entire fish. 

 The mouth opens obli€|ue]y downwards; the jaws are armed with great numbers of 

 minute teeth. The eyes are circular ; the diameter of the eye is equal to about one 

 quarter the length of the head. The lateral line commences at the posterior superior 

 angle of the operculum, and pursues a slightly declining course to a line over the anus, 

 from which it passes in a straight line to the tail A strongly marked carina upon each 

 side of the tail, which is crossed by twelve or more plates. 



Upon the dorsum are situated from eight to ten incurved spines, inclining to the right 

 and left. The first of these spines arises on a line midway between the opercula and 

 pectoral fin. 



The dorsal fin arises on a line directly above the anal spine, and gradually diminishes 

 in height, until its rays are scarcely perceptible. 



The ventral spines are stout, sharp, somewhat incurved, serrated upon their upper 

 edge, with a membrane at their base. A bony plate is situated between the ventral 

 spines, which terminates posteriorly in a point. 



The anal fin is similar in its form to the dorsal ; its spine is recurved. 



The caudal fin is rounded. 



The fin rays are as follows: — D. 8 or 9 or 10. 1-7. P. IL V. 1. A. 1-9. 

 C. 13. Length one to two inches. 



Remarks. This pretty species, which is less common than the quadmcus, h found in 

 the salt marshes along the sea-coast, in company with that species and the different 

 killifish. 



VOL. V. NEW SERIES. 14 



