228 BUMPUS. [Vol. V. 



The Egg soon after Oviposition. 



Though many efforts were made to secure absolutely fresh- 

 laid eggs, I succeeded in finding nothing earlier than what is 

 represented on PL XIV, Fig. B. The female bearing these eggs 

 was captured on the morning of July 22, 1890, off the island of 

 Cuttyhunk. The eggs were very dark in color, closely packed 

 together, and were much more irregular in shape than when 

 examined a few days later, many being almost triangular in 

 outline. 



When examined under a lens, the yolk was found to be flat- 

 tened upon one side, in some cases becoming even concave. A 

 clear fluid was collected at this region, possibly the same as 

 that described for the ovarian egg. 



Relatively small vesicles, the polar globules, are seen at R-k. 

 They are present in many eggs, and appear to be attached at 

 no special point of the vitellus, so far as the flattened area is 

 concerned ; being sometimes within it, and sometimes without. 

 It may be, however, that I have only seen them in secondary 

 positions ; for in some cases they seemed to move freely about 

 within the egg membrane. They were not observed in process 

 of formation, nor were they invariably present. Before the blas- 

 tula is formed, they disappear. 



Attention has already been called to the secretion of the col- 

 umnar cells of the oviduct, which in Homarns forms a varnish- 

 like layer immediately over the primary egg-membrane, becoming 

 inseparably united with it. It may be that a similar secretion 

 on the part of the female of Eupagnrus produces the change in 

 the texture of the egg-membrane which Mayer (yj) has described 

 for that form. It certainly renders the primary covering much 

 more impervious to water and to reagents, besides making it 

 very much tougher. 



The primary egg-membrane with its outer coating I shall call 

 by the indifferent term, capsule. Though a delicate layer of 

 protoplasm covers the egg within the capsule, no distinct invest- 

 ing membrane comparable with a true vitelline membrane can 

 be said to exist. 



In Atycpliira a " secondary membrane " is formed by the cells 

 of the oviduct in much the same way as is probable in Homarus, 

 but later on in the former the two become separated and a fluid 



