II-l BULLETIN OF THE BUREAU OF FISHERIES. 



It was learned from the examination of large collections that the ratio of males to 

 females is about equal. It so happens, however, for unknown reasons, that at times a 

 school which consists almost wholly of females is taken, and again the reverse is true. 

 The females are constantly somewhat larger than the males, their average length being 

 about ioo millimeters, with a maximum length of 123 millimeters. The average length 

 of the males is about 89 millimeters, with a maximum length of 112 millimeters. The 

 food of this species consists of small fish, crustaceans, algae, and diatoms. 



SPAWNING. 



Spawning occurs from early spring to late summer, ripe or nearly ripe fish having 

 been taken by the writer during March, April, May, June, July, and August. Eggs of 

 several sizes are present in the ovaries at one time. When one lot is spawned, the eggs 

 of the next lot are large enough to be seen with the unaided eye. The presence in the 

 ovaries of several different sizes of eggs at one time -strongly suggests that spawning 

 occurs more than once and perhaps several times during the season. An average-sized 

 female produces as many as 500 eggs at one time, and the eggs can easily be hatched 

 artificially. The writer has hatched them during cool weather by merely placing them 

 in a shallow glass dish at the time of fertilization and leaving them undisturbed and 

 without change of water until the young fish appeared ; but when the weather is warm 

 an occasional change of water is essential. 



The eggs are deposited in shallow water along grassy shores, where large schools of 

 fish collect for this purpose. Capt. Charles Willis, 1 a resident of Morehead City, N. C, 

 found a very large school of silversides spawning among eelgrass, in shallow water near 

 Morehead City in May, 1915. The eggs were attached to the vegetation in clusters and 

 became exposed at ebb tide. He then collected and preserved about a quart of the 

 eggs, together with several specimens of the fish which he later exhibited to the author. 



EGGS. 



The eggs of this species are approximately \% millimeters in diameter and are 

 slightly heavier than sea water. Their form is spherical when spawned, and they remain 

 so until hatched. The eggs to the unaided eye appear to be separate when first spawned, 

 but as soon as exposed to water, opaque threads of considerable length become visible 

 at the upper pole of the egg. If the water is agitated, the threads become visible more 

 quickly than they do in quiet water; likewise the eggs appear to become attached to 

 objects in the water or to each other more quickly. The addition of the sperm, too, 

 seems to hasten the formation of the opaque threads. A microscopic examination, how- 

 ever, showed that the eggs are delivered in a transparent gelatinous mass, consisting of 

 more or less definite strands, but, as already indicated, the mass does not become 

 opaque and definitely threadlike until exposed' to the elements. The strands again 

 become transparent after they have been exposed for a somewhat variable period of 

 time, and then they are elastic like rubber and of very remarkable strength. It was 

 necessary to use glassware and glass apparatus for incubating and handling the eggs, 

 as they readily adhered to all other materials with which they were placed in contact. 



1 Capt. Willis was employed lor several seasons by Mr. Russell J. Coles in the latter's investigations of the fishes of Cape Look- 

 out. It was through this employment that Capt. Willis's interest in the natural history of fishes was stimulated. 



