NO. 2280. THE NEW COPEFOD FAMILY i^PHYRIIDAE— WILSON. 553 



with weak chelae, the appendages themselves are so small and short 

 that they are not capable of doing any real work. The locomotion of 

 the Rehelala male is doubtless greatly facilitated by the increased 

 lengtli of the basal joints of the maxillipeds. This makes possible a 

 much longer reach between the second maxillae and the maxillipeds, 

 and the male must be able to move about quite freely. The males 

 retain the ability to perform this sort of locomotion during life. 

 But after they have found their host, or after they have attached 

 themselves to the body of the female, they lose their swimming legs, 

 so that they are no longer capable of free swimming. These males 

 thus go a step farther than those of the Lernaeopods, for the latter 

 sometimes retain their swimming legs although they are no longer of 

 any service as locomotor organs. 



Prehension. — The organs of prehension are the same as those with 

 which the parasite crawls about over the body of its host, namely the 

 second maxillae and maxillipeds. And the male continues to use 

 them for both purposes throughout life. Accordingl}'^ we find that 

 these organs persist in the male, that they increase in size with the 

 growth of the body, and that they retain a very well-developed set 

 of muscles, which renders them efficient for both prehension and 

 locomotion. But the female, after she has once burrowed into the 

 tissues of the host, develops processes or horns, or both, upon the. 

 sides of the cephalothorax, which anchor her firmly in a fixed posi- 

 tion, so that she has no further need for organs of prehension. And 

 the maxillae and maxillipeds, thus rendered useless, entirely disap- 

 pear, or if they persist they do not increase in size Avith the enormous 

 increase of the female's body, and evidentlj' do not function at all 

 as prehensile organs. 



Burrowing. — "While the genera belonging to the Sphyriidae are 

 much more limited in their choice of a point of attachment than those 

 of the Lernaeidae, and while none of them, so far as yet known, ever 

 burrows into the fish's heart, or penetrates the tissues of its host to 

 anything like the distance accomplished by Pennella.^ nevertheless 

 their burrowing is similar in all respects to that of the Lernaeidae, 

 and is probably accomplished in the same manner. Fortunately a 

 few of the specimens in the United States National Museum collection 

 had been secured by cutting out a block of the tissues of the host 

 large enough to include all of the parasite's head and neck. In this 

 way it Avas possible to determine that the dorsal aorta was the blood 

 vessel usually sought, and that, in reaching it, the parasite found the 

 same difficulties noted in the Lernaeidae.^ But in the present family 

 the second attennae can not take as prominent a part in the bur- 

 rowing as they did among the Lernaeids, and accordingly it must 



1 Proc. U. S. Nat. Mus., vol 53, p. 16. 



