ALASKAN ISOPODS. 



219 



A number of drawings are presented of the li rst incubatory lamella and the sixth leg of Bopyroides 

 hippolytes I Krovcri, from specimens found <>n the same and on different hosts, taken from the same 

 and from different localities. The slight variations seen to exist in specimens coming from different 

 hosts is paralleled by variations of a similar nature in specimens coming from the same host. If these 



ir </" 



Fig. 7. — sixth let,' of Bopyroides hippolytes. a. Found on Spironiot arts polaris* from west of Pribilof Islands; - -V2. />, On 

 Spironiocaris suckleyi from station l-'J'J; 41, c, On Spirontocaris suckleyi from station 4268; 52. d, On Spirontocaris 

 suckleyi from station 4220; 52. ef, On Spirontocaris suckleyi from station 4^7y. /. On Spirontocaris ht rdmaniirom station 

 4199; 77.1. .'/I.'" 1 Pandalus jordani from station 4203. 



variations can not lie considered as individual, more marked in this group of isopoda than in any other, 

 owing to the parasitic mode of life, there seems to be no other course possible than to make a new 

 species of each individual. As these differences are slight, and as the genera! form of the parts is 

 about the same, it would probably lie betterto consider them simply as variations or modifications. 



♦The parasite from S. polaris has distinct ovarian bosses en the first four segments of the thorax. 



t See first note on page 218. Enlargement, e 1 , ■ 39; e 2 , ■ 52; e 3 , < 52. 



t See second note on page 218. Enlargement, #', 39; g 8 , 52; g*, x 39; g*, ■ 41; gS, 



