No. 503] SHORTER ARTICLES AND CORRESPONDENCE 731 



isolation is needed for evolutionary divergence to become mani- 

 fest. If Dr. Gulick really agrees with me that evolution is 

 spontaneous, I must submit that his adherence to the custom 

 of treating isolation and selection as factors has served to con- 

 ceal his conclusions, rather than to announce and defend them. 



0. F. Cook. 



A NOTE ON THE SILVEBSIDB 

 In view of its value as a food fish, and as food for other more 

 valuable fishes. 1 the following note on the habits of the silverside 

 has special interest, 



At Chesapeake Beach, Md., April 19, 1908, p. m., the tide was 

 rising and probably pretty well up. At points where weed and 

 such riff raff was partially buried in the beach, in the wash of 

 the ripples which followed one another in. numerous fishes were 

 wiggling actively as though stranded. At times one would be 

 almost or quite clear of the water, but so active were they that 

 the writer, not having a net. was at first unable to capture any. 

 They evidently knew what they were doing, as when a spot they 

 occupied was approached, they disappeared from it. Finally, 

 by striking quickly with a piece of wood at a place where some 

 were congregated, three were disabled and secured, which proved, 

 as anticipated, to be Menidia menidia. 



Examination of a specimen of beach trash collected where the 

 fishes were observed, at the time, shows the presence of a number 

 of eggs, apparently of Mmnlin. strong evidence that the fish were 

 spawning. These eggs are one mm. or a little more in diameter 

 and bear filaments at one point which attach them to the beach 

 material in which they occur more or less scattered. The white 

 color of the egg (preserved in alcohol ) is relieved by yellow oil 

 masses. This spawn iuir around, if such it was. would certainly 



Chesapeake Bay is neutral ground between the northern and 

 southern races of Mniidia mrnidia, and the writer prefers to 

 refer the specimens obt* ' 



