THE SILVERSIDES OF THE GENUS MENIDIA. 247 
haus are so different that it seems likely that the two observers may 
have examined different species. This supposition is also warranted 
by the fact that the specimens came from different localities. Pro- 
fessor Moenkhaus says: 
Menidia notata.—Eggs were obtained in abundance from June 1 to July 2, 1901. 
At Cold Spring Harbor eggs were taken until July 15. The eggs are usually not 
perfectly spherical, but have various slight irregularities. At one pole there is a tuft 
of about 50 filaments, very elastic and several times the diameter of the egg in length. 
These become matted together, forming a central core around which the eggs are 
clustered like grapes around the stem. The protoplasmic disk is comparatively large. 
The eggs when ripe are exceedingly easily expressed, so that the fish must be handled 
rather carefully. A good-sized female yielded 1,413 eggs. 
Dr. Bumpus has published the following notes* regarding the 
spawning time of silversides on Cape Cod: 
Two species of Menidia (gracilis and notata) abound in the neighborhood of the 
laboratories. The following has been taken from the notes kindly furnished by 
Dr. C. Judson Herrick: 
“On June 5, 1896, Mr. Edwards found Menidia notata spawning at Hyannis in vast 
numbers. At this time the fish had selected a point in the beach grass above the 
low-tide level, and at low tide the eggs were consequently exposed to the sun and 
dried. Mr. Edwards noted great quantities of spawn and milt, and collected about 
a quart of the former. 
“During the last days of June and the first ten days of July of the present year the 
fish were very scarce, though Dr. Herrick found a few ripe females and a very few 
males. The eggs adhere to each other in thick, ropy masses, and to any foreign 
object with which they come in contact by means of long threads. Both fertile and 
unfertile eggs sink to the bottom, and the first cleavage plane appears in about one 
hour. The eggs may be artificially hatched in jars of running water, the period of 
incubation being ten days. The young fish, which carry a small yolk-sac, are about 
6mm. in length. Fry were skimmed from the surface of the harbor on July 4, and 
measured 1.5 cm. in length. On July 9 fry similarly taken measured 2.25 cm. in 
length. 
“The eggs of Menidia gracilis resemble those of Menidia notata, but the species seems 
to breed later, since many ripe females were taken during the first week in July. 
The eggs, however, do not undergo artificial fertilization as readily as those of the 
first species.”’ 
FOOD OF THE SILVERSIDES. 
The silversides subsist upon minute animal and vegetable organisms, 
particularly small crustaceans, and doubtless devour a great many 
floating eggs of other fishes. Dr. Smith informs me that he has found 
several with young lobsters about three-fourths inch long in their 
stomachs. As may be seen in the appended tables, the bulk of the 
food of the common northern silverside consists of small crustaceans, 
but they eat whatever meat falls within their reach, not disdaining 
the eggs and young of their own kind. That they feed both at the 
surface and at the bottom is clearly shown by the character of the food. 
Copepods, other free-swimming crustaceans, and insects are frequently 
eaten; and often mud, alge, and diatoms from the bottom are found 
in their stomachs. 

*H. C. Bumpus, Science, N.§S,, vol. vit, No. 207, p. 4, December 16, 1898. 
