NO. 2063. NORTH AMERICAN PARASITIC C0PEP0D8— WILSON. 571 



maxillae of the female, and it is possible tliat tliey can crawl along 

 these appendages to the fish's gills and there obtain food. But that 

 does not seem very likely, because there are many species in which the 

 second maxillae are as long as the entire body, and a few species in 

 which they are two or three times the body length. Such a distance 

 would make a rather long journey for so slow moving a creature as 

 the male, and if it was a case of traversing the distance or going 

 hungry, it would most likely result in the latter. Possibly the male 

 may be brought close enough to the gill when the female draws her 

 body down to obtain food. At all events the male must derive what- 

 ever food he eats from the. fish host and not from the body of the 

 female . 



5. The spermatophores attached by the male to the sexual open- 

 ings of the female are large and contain a goodly number of sperma- 

 tozoa. Probably a single pair of them would supply the female with 

 sufficient spermatozoa to fertilize all the eggs she can lay during her 

 lifetime. Furthermore, the careful study of the sexual organs of the 

 male given on pages 590, 691, indicates that only a single pair of 

 these spermatophores are formed. Hence it is unlikely that the male 

 lives very long after fastening the fii-st pair in place. 



6. Both sexes necessarily go without food during the free swimming 

 period, since their mouth parts then are only suited for obtaining food 

 parasitically. During the second copepodid stage they both suck the 

 blood of the fish upon which they have fastened. The female uses 

 this food to increase greatly in size, as well as to develop her various 

 organs. Tlie male does not increase at all in size, but devotes all his 

 food to the maturing of the spermatophores. After these are fully 

 developed and put in place on the body of the female no more food is 

 required unless a second pair is to be formed, and even then the amount 

 of food demanded would be relatively much smaller. On the contrary, 

 the female must have an abundance of food to ripen her eggs, to cairy 

 them in the external sacks until they hatch, and to form, ripen, carry, 

 and hatch successive new batches of eggs. In view of these considera- 

 tions it is reasonable to suppose that the duration of life for the male 

 is much shorter than that of the female. He requires Httle, if any, 

 food after he has transferred from the host to the body of the female. 

 And the absence of an intestine and anus would insure the complete 

 digestion and absorption of all the food taken previously. It seems 

 probable, therefore, that the male does eat the fish's blood while it 

 remains attached to the giUs, but that it gets no food after it has 

 transferred to the body of the female. 



MORPHOLOGY. 



Oeneral hodyform of female. — Owing to the degeneration consequent 

 upon fixed parasitism there has been a fusion and elimination of the 

 various body regions. We can no longer distinguish a cephalon, a 



