346 ASELLID^E. 



is about half a line long, and transparent under the 

 microscope. 



" The young in one instance were observed to be hatched 

 during the week previous to the 22nd July, but in one 

 year each of these specimens had a cluster of white ova 

 on the thorax in the middle of September. 



" The posterior extremity of the young is proportion- 

 ably more obtuse than in the parent. Further, unless it 

 be immediately or speedily consequent on production from 

 the ova, they do not seem to undergo any conspicuous 

 metamorphosis. 



" Exuviation is less frequent here than in many other 

 crustaceans. The integument, however, separates in 

 two portions, which are nearly white. 



" This is an extremely pacific, tranquil creature, always 

 seeking shelter. Specimens have survived many months 

 when kept in confinement." 



The development of the eggs and young of this species 

 has been carefully investigated by De Geer, in his great 

 work on Insects, and more recently, in greater detail, by 

 Rathke,* from whose elaborate series of illustrations the 

 accompanying figures have been selected. 



The eggs having been discharged from the oviduct, 

 are entirely destitute of any trace of germ, and are 

 retained and hidden beneath the four pairs of large, 

 slender, and semi-transparent scales attached to the under 

 surface of the body of the female, where the young are 

 disclosed, and remain until they have assumed a form 

 similar to that of their parents. Our first figure repre- 

 sents the egg in its early state, filled with the yolk and 

 enclosed in a thin chorion. 



* Abhandlungen zur bildungs und entwickelungs Geschichte des menschen 

 und der Thiere. Liepzig, 1832, 4to, Erster Theil, p. 3 tab. 1. Translated in 

 Annales Sci. Nat., 2 ser. Zool. torn. 2. 



