Vol. X. MarcJi, 1906. No. ./ 



BIOLOGICAL BULLETIN 



CORRELATION IN THE DEVELOPMENT OF 

 FASCIOLARIA. 1 



O. C. GLASER. 



The following pages contain in abstract an account of the 

 embryology of the prosobranch Fascio!aria tnlipa (var. distans), 

 and a discussion of such occurrences in its development as seem 

 to me to be of general interest. 



I. THE CANNIBALISM OF FASCIOLARIA EMBRYOS. 



The breeding season of Fasciolaria at Beaufort, N. C., lasts 

 from about the first of May until the first of July, although egg- 

 cases containing various stages of development were occasionally 

 found in August. The capsules, held together by a basement 

 membrane fastened to oyster shells, conchs or wharf-piling, occur 

 in bunches of I 5-30 varying in size from one half to three inches 

 across. 



When fresh they are soft and so translucent that the pink or 

 white eggs suspended in their albuminous contents give their color 

 to the whole mass ; later, however, the egg-cases become firm and 

 elastic, and obscured by the algae, polyzoons, and other organ- 

 isms which grow over them. Often isolated capsules, or bunches 

 containing only a few are found. These are produced either by 

 females interrupted at laying, or by young females, which usually 

 deposit fewer and smaller capsules than the old ones. The last 

 capsule to be laid in a bunch, whether deposited by an old or 



1 For the privilege of collecting the material on which this work was done I am 

 indebted to the Hon. George M. Bowers, U. S. Commissioner of Fisheries. The 

 preparation of this paper was begun during my tenure of the Adam T. Bruce fellow- 

 ship in the Johns Hopkins University, and was finished for the press in the Zoological 

 Laboratory of the University of Michigan. 



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