30 PROVEEDlNOa OF THE NATIONAL MVHEUM. vol.53. 



strings but with all the eggs separate and in close contact one with 

 another. Those near the opening of the oviduct are about twice the 

 size of those at the center and these in turn are much larger than 

 those at the posterior end. The increase in size is accomplished by 

 the absorption of food material or yolk, which goes on with much 

 greater rapiditj at the anterior end just as the eggs i)ass out into 

 the oviducts. In the latter the eggs are arranged in a single row 

 and are strongly flattened, so that they look like coins standing on 

 edge. • 



The external &g,g sacks are short and bag-shaped in the Lernaeinae, 

 and the eggs are piled looselj^ into them, with almost no flattening 

 and without definite arrangement. In the oviducts also of this sub- 

 family the eggs are spherical instead of l)eing flattened, and they do 

 not quite touch one another. In the other genera the egg sacks are 

 filiform and very long, reaching 12 to 15 inches in the genus Pen 

 nella^ and the eggs are arranged in a single row and flattened as they 

 were in the oviducts; but there is this difference: In the oviducts the. 

 eggs are in actual contact, while here in the external sacks each is 

 separated from its neighbor on either side by a partition formed of 

 the Qgg membranes. 



In the Lernaeinae the developing larvae are not arranged in any 

 order with reference to the walls of the egg sacks, but in the other 

 subfamilies there is the same arrangement as in the Caligidae-— - 

 namel3^ the body of the nauplius appears on one of the flattened sides 

 of the egg, with the head on the edge of the egg that is nearest the 

 outer lateral margin of the sack. The long axes of the nauplii are 

 usually parallel, but occasionally one is reversed in position; and, 

 similarly, while most of the nauplii are on the proximal surface of 

 each ^gg^ occasionally one will be found on the distal surface. 



Fertilization, as already stated, occurs during the last copepodid 

 stage; the spermatophores are attached by the male in pairs to the 

 ventral surface of the genital segment of the female, their openings 

 being brought into contact with the vulvae. The contents of the 

 spermatophore then pass into the enlarged end of the oviduct inside 

 the vulva and the emptied sack di'ops off. According to A. Scott in 

 Lemaeocera hranchialis the first pair of spermatophores are re- 

 placed by others in succession until the receptacula are filled, each 

 receptaculum holding the contents of four spermatophores. At 

 first the four lots remain separate in the oviduct, but they soon mix 

 and become one homogeneous mass. 



A. Scott concluded that in Lemaeocera "the spermatozoa at once 

 pass up the rudimentary oviduct to the ovary and fertilize the 

 eggs." (1901, p. 43.) But there are several considerations which 

 render such an action highl}'^ improbable: 



