No. 646] SHORTER ARTICLES AND DISCUSSION 471 



The literature affords so few eases of marine animals reared 

 under laboratory conditions that the writer ventures to com- 

 municate his successful attempts to carry throufrh to sexnal 

 maturity the nereid, Platunercis megalops, from egjrs laid in the 

 laboratory. This work had its origin in a suggestion made by 

 Dr. F. R. Lillie in 1911 that the capacity for cross fertilization 

 between Nereis limhata and Platynereis megalops be tested. At 

 that time, hoM-ever, since we knew so little of the life history of 

 these forms, we felt that it was necessary to get all data possible 

 on each life history in order to have a standard of comparison 

 for the life history of the hybrids. So far all efforts to cross these 

 nereids have failed. The difference in the breeding habits of 

 Nereis and Plaf)j»ereis is so striking that this alone might ac- 

 count for tho failure of cross fertilization. Nereis sheds eggs into 

 the Wilier wiiciv fertilization takes place; Vlatmcrek lays in- 

 M i.iiii.iti ,1 . j.^. 1 after copulation. lIo^^ever, this very differ- 

 ence is ealculated to enhance the interest attachinff to the cross 

 fertilization. It mmlit l)e possible to study the inheritance of the 

 egg-laying reactions. In iulditioii, i';\v\y ohMTvaiions revealed 

 that the young I'hit ,/>" " ux^iulnp. 1\ rrsemble Nereis 



plex life history, we felt that the life history of Flat if nereis 

 might well repay study for its own sake. 



II 



Platyxereis megalops Reared i^xder Laboratory Coxditioxs 

 TO Sexual Maturity 

 The writer has found that it is possible to rear Platynereis 



wasfirit aee(uuplixlH.(l i„ l!)l;i-i:)14. ivpented in 1 1120-1921, and 

 again in 1921-l!>1^2. The iv>ults may he hrieHy n'cc.nnted. 



Males and females eaiej-lit with a lumd net in the evenings of 

 the July and the AuLnist full nioi.n air kept in separate dishes. 



