532 Phylum Mollusc a 



portional to the size of the female, as is shown by the following table: 



Relative vol. 

 Species No. of Eggs Diam. of Egg of Female 



C. plana 9000 136" 13 1/3 



C. fornicata 13200 182" 30 



C. convexa 220 280" 1 J4 



C. adunca 180 410" 4 1/6 



In both C. convexa and C. adunca there is no free larval life, the young 

 issuing from the capsules in adult form. 



The eggs are fertilized when laid, and it is generally impracticable to 

 obtain them unfertilized for purposes of artificial fertilization or par- 

 thenogenesis. The best way of getting very early stages is to remove 

 mature females from their substrate and to place those which have not 

 laid in glass dishes in running seawater. After a few hours, preferably in 

 the early morning, the water may be poured off and the under surface 

 of the female examined through the glass. In this way one may find 

 females in the process of laying and may obtain the earliest stages, or 

 may fill the dish with water and may then take the eggs at any later 

 stage desired. 



Since the capsules are thin and transparent the eggs may be studied 

 under the microscope or may be subjected to experiment while still in 

 the capsules. For serial sections they may be fixed, stained, and 

 sectioned while still in the capsules, but since the eggs contain a good 

 deal of yolk and are relatively opaque, it is necessary in order to study 

 in whole eggs the details of fertilization, cell division, etc., to tease them 

 out of the capsules with needles, and then to fix, stain, and mount them 

 for microscopical study. 



CULTURE METHODS FOR UROSALPINX CINEREA 



H. Federighi, Antioch College 

 RANGE AND OCCURRENCE 



THE common oyster drill, Urosalpinx cinerea, inhabits the marine and 

 brackish water of the Atlantic coast from Maine to Florida. It has 

 been collected in San Francisco Bay, in Bermuda, on the Gulf coast, and 

 recently has been reported from England (Federighi, 1931a). 



It occurs at depths ranging from between the tide levels to a maximum 

 of approximately 25 feet. Soft mud and hard sands are not favorable 

 for its growth and multiplication. 



FEEDING HABITS 



Although U. cinerea has been called the oyster drill because it is known 

 to eat oysters in preference to other animals, the author has observed it 



