igi6.] 



Fauna of the Chilka Lake : Terrestrial Isopoda. 



473 



this is the proportion given by Miss Richardson who makes use of this character in 

 her analytical key of the species of the genus. 



The young taken from the incubatory pouch (fig. 22) of the female is 3 mm. long 

 and i - 5 mm. broad. The eyes occupy the whole 

 lateral side of the head and are larger in propor- 

 tion to the body than in the adult. The seventh 

 segment of the peraeon is short and only partially 

 developed and bears no appendages. The first an- 

 tennae are larger in proportion than in the adult 

 and can be seen projecting slightly beyond the 

 anterior margin of the head , while the second anten- 

 nae are short, being less than half the length of the 

 body. The uropoda are also less than half as long 

 as the body, being only about one-third, and have 

 the two branches equal in length, the inner one bear- 

 ing a long seta at the extremity, nearly half as long 

 as the inner branch itself. The posterior margin of 

 the terminal segment is regularly rounded and not 

 produced into a point in the middle as in the adult. 



Fig. 22. — Ligia exotica, dorsal view 

 of young taken from incubatory pouch 

 of female. 



I have been able to compare the Lake Chilka 

 specimens with specimens from Honolulu, Hawaiian 



Islands, sent to me some years ago by the late G. W. Kirkaldy. These Honolulu 

 specimens agree in all the points given in the short specific diagnosis above with those 

 from Lake Chilka, and must undoubtedly be referred to L. exotica, which had already 

 been recorded from Honolulu by Miss Richardson (1905, p. 676); they differ, how- 

 ever, slightly in that the inner margins of the carpus and merus of the first, second 

 and third legs of the male bear more numerous setae than in the Lake Chilka speci- 

 mens. Some of the specimens also are slightly more slender and have the antennae 

 a little shorter in proportion to the length of the body, though in others the uropoda 

 are longer in proportion and more slender. 



In some of these points the Honolulu specimens appear to approach L. baudi- 

 j li a na, Milne-Edwards, a species common on the eastern coasts of America as far south 

 as Rio de Janeiro, and at the Bermudas, Bahamas, etc. ; and it is possible that when 

 full series of both species are examined, it may be difficult to find characters separat- 

 ing them in all cases. In L. baudiniana, however, the propod of the first leg in the 

 male has no process at its distal end. This is present in some of my Honolulu speci- 

 mens of L. exotica, though in some of the younger males it is small and hardly distin- 

 guishable. Probably, however, it is only developed to a full extent in fully mature 

 males. In L. baudiniana, it seems to be replaced, as it were, in fully developed 

 males by the distinctly marked row of setules on the inner margin of the carpus of 

 the first leg. 



In 1890 in his account of the terrestrial Isopoda collected by the ' Challenger,' 



