Chap. VIII. DEVELOPMENT OF LIGIA. 69 



CHAPTEE VIII. 



DEVELOPMENTAL HISTOKY OP EDRIOPHTHALMA. 



Less varied than that of the Stalk-eyed Crustacea is 

 the mode of development of the Isopoda and Amphi- 

 poda, which Leach united in the section Edriophtlialma, 

 or Crustacea with sessile eyes. 



The Rock-Slaters {Ligia) may serve as an example 

 of the development of the 

 Isopoda. In these, as in 

 Mysis, the caudal portion p. 

 of the embryo is bent 

 not downwards, but up- 

 wards ; as in Mysis also, 

 a larval membrane is 



Fig. 36. 1 



first of all formed, within 



which the Slater is developed. In Mysis this first larval 

 skin may be compared to a Nauplius ; in Ligia it appears 

 like a maggot quite destitute of appendages, but pro- 

 duced into a long simple tail (tig. 37). The egg-mem- 

 brane is retained longer than in Mysis ; it bursts only 

 when the limbs of the young Slater are already par- 

 tially developed in their full number. The dorsal sur- 



^ Fig. 36. Embryo of Ligia in the egg, magn. 15 diam. D. yelk ; 

 L. liver. 



