SCOPE AND METHODS. 21 



constantly for control and important variations are noted 

 in the text. 



The plots are accurately drawn to scale, the magnifica- 

 tion being indicated in each case, so that measurements 

 in the text are, as a rule, unnecessary. The figures on 

 the scales in the margins of the plots indicate the 

 serial numbers of the sections plotted, the sections 

 being in. all cases fifteen micra thick. To facilitate 

 the location on the plots of objects mentioned and to 

 avoid the introduction in the text of detailed measure- 

 ments, these serial section numbers are often referred 

 to in the descriptions. 



The genus Menidia contains two species, both of 

 which are commonly called "silver-sides." They are 

 very abundant near Woods Hole, Mass., swimming 

 in close schools in shallow water, the larger one, 

 M. notata, being found along the open shores, while 

 the smaller one, M. gracilis, is more commonly taken 

 in the protected bays and tide pools. They are both 

 small species, the larger one being about lo cm. 

 long. Their food in captivity seems to be mainly small 

 crustaceans, such as the megalopa larva of the com- 

 mon crab, though they eat smaller fishes of their own 

 or other species. 



Regarding the relationships of the family Atherinidae, 

 to which they belong, I am permitted to make the fol- 

 lowing quotation from a personal letter received from 

 Dr. Theo. Gill. ' ' The Atherinids, I think, are a prim- 

 itive type of Acanthopterygian fishes, near the border 

 line between ordinary physostomous and physoclistous 

 fishes. They are genetically related to the ancestors of 

 the pikes, the cyprinodonts and the mullets — related to, 



