FISHES OF CHESAPEAKE BAY 
179 
failing to reach eye, shorter than diameter of eye; sides with deep, well-developed, bony scutes; 
opercle finely striate; a large naked area in front of pectorals; innominate bones united, forming a 
narrow spinelike plate on the abdomen, somewhat shorter than the ventral spines; free dorsal 
spines strong, the first inserted over base of pectorals, the second the longest, nearly equal to length 
Fig. 92 . — GasUrosleus aculeatus. From a specimen 2}4 inches long 
of snout and eye, the spine connected with soft dorsal short, the soft rays very low; caudal fin 
apparently slightly emarginate; anal fin similar to soft dorsal, the spine preceding it very short; 
ventral fins with large serrated spines, directed sidewise when set, reaching origin of anal when 
deflexed; pectoral fins moderate, inserted in advance of ventrals, 
1.45 to 1.75 in head. 
Color dark greenish above, lower parts silvery; back and 
upper parts of sides with indistinct dark bars, the last one of 
these on base of caudal. 
Only two specimens, a male and female, respectively, 25 and 
26 millimeters (1 inch) in length, were secured. This species is 
readily distinguished from the common four-spined stickleback 
of Chesapeake Bay by the bony plates on the sides. Published 
accounts give number of side plates as 28 to 33 and the number 
of dorsal spines as occasionally 3, rarely 4, in advance of the small 
spine at the base of the soft fin. 
Much individual variation appears to exist among the 
group of mailed or partly mailed sticklebacks. Dr. W. C. Ken- 
dall, who has made an extensive study of these sticklebacks (un- 
published), informs the writers that the American two-spined stickleback is doubtfully distinct 
from the European stickleback, and that, in any event, the name bispinosus, used by Jordan and 
Evermann (1896-1900, p. 748), is not available for this species. We therefore tentatively refer our 
specimens to the European species 
aculeatus. 
The stomachs of the two speci- 
mens at hand contained as food prin- 
cipal^ copepods; also small eggs 
(probably of insect origin) and frag- 
ments of alga. 
Spawning apparently takes 
place in the spring at Woods Hole, 
the time being from June to July. 
This species, like the four-spined 
stickleback, is reported to build nests, in which the eggs are fanned and guarded by the male. 
For an account of the eggs, embryology, and larval development the reader is referred to Kuntz 
and Radcliffe (1918, pp. 130 to 132, figs. 113 to 121). 
The species is said to reach a length of 4 inches. It is principally of northern distribution, 
occurring, according to Jordan and Evermann (1896-1900, p. 748), only as far south as New Jersey. 
Lugger (1878, p. 118), however, recorded it under the name Gasterosteus noveboracensis, from 
Sinepuxent Bay, on the Atlantic coast of Maryland. The present record appears to be the first 
from Chesapeake Bay, where it undoubtedly is rare. 
