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THE AMERICAN NATURALIST [Vol. LV 



piercing organ, which is capable of puncturing the tissues 

 of the host for purposes of sucking blood. This is the 

 exact method by means of which the attached parasite 

 feeds itself. 



About a week after attachment to the host, the modi- 

 fication of the parasite has been so complete that one can 

 hardly recognize any resemblance between it and the free- 

 living larva from which it was derived. In another week 

 and a half, that is, about two and a half weeks after 

 attacliiticiit, tlu' (*o])cpods have reached sexual maturity 

 and arc ivad.x to iiiulergo fertilization. The males can 

 now 1m' ( <li>tiiiguished from the females. This was 

 not pos>il)l(' prcx iously. The females are veritable giants 

 as comi)ared with the males, being about three or four 

 times the size of the latter. 



The only male ever discovered in the genus Sahnincola 

 is that of Salmincohi cdH-tirdsii, which has been described 

 and figured in the h'if>lnalral nullrlii, for 1914. The 

 writer has just com})l('t((l the studs- of anotlier- male of a 

 different species of Sdhiinicola, naiiicly, Salnnncola beani 

 Wilson which lie recently discovered on the gills of the 

 Chinook salmon.' This new male shows the same size 

 difference when compared with the female as does the 

 male first mentioned. 



Prior to fertilization, the males and females hang side 

 by side on the tissues of the host. In order to accomplish 

 fertilization, the male undergoes a rather peculiar be- 

 havior. He begins circling movements and somewhere 

 in his vicinity he comes in contact with a female. As 

 soon as this occurs, the male clasps the female with his 

 maxi]lii)ods and at the same time he releases his hold on 

 the ti-Mics of the ho<t. The male tlien creeps towards 

 the po^tci ioi- ic-ifui ot" the tVnudc's body, in the neighbor- 

 hood of the -viiilal poics, and hd'c he attaches himself in 

 l»ovitiuii I'oi' rci-iill/ation. The male next bends his abdo- 

 JiM'ii iipwai'd towafd the u'cnital openings and soon 

 extrudes two pear-shaped pouches known as spermato- 



