contains a number of ova fertile and unfertile. The unfertile 

 eggs serve as food for the larvae developed from the fertile 

 ones and there is a certain amount of competition between the 

 larvae in the capsule which results in the most vigorous larvae 

 getting more food and making a larger growth than the more 

 weakly coinhabitants of the capsule. Thus at the time of 

 leaving the capsule and coming into the outer world, it some- 

 times happens that there will be perceptible differences between 

 the individuals issuing from a single capsule, not only in actual 

 size but in the length of the coil of whorls and the size and 

 compactness of the larval apex." 



In the beam trawl only a small percentage of the larger 

 shells that get into the net actually reach the deck of the vessel, 

 most of them going through the coarse-meshed net before reach- 

 ing the pocket; thus their relative abundance is only proble- 

 matical. As it was, the number of Chrysodomus decemco status 

 was about double that of Buccinum undatum. In all, some 56 

 specimens were collected, including some of remarkably large 

 size. One Chrysodomus measured 5.5 inches with about 0.25 

 of an inch broken away, making its total length about 147 

 mm., with a diameter of 90 mm. Gould gives the length as 

 3 inches, and Tryon 2.5 to 4 inches. The number of ribs varies 

 somewhat, about one half having ten (counting the subsutural 

 rib), one fourth eleven, and the other fourth nine ribs. 



The specimens of Buccinum collected were also unusually 

 large for New England waters, one with apex broken measuring 

 nearly 5 inches or about 125 mm. in length, with a diameter of 

 2.5 inches. Gould gives its length as usually 3 inches, and 

 Tryon 3.25 inches. The specimens also varied greatly in form 

 and sculpture, the spire in many being unusually high, with 

 the longitudinal undulations wanting on the body whorl. 



EXPLANATION OF PLATE. 



Fig. 1. Egg-capsules of the Common Whelk (Buccinum undatum). 

 Fig. 2. Egg-capsules of the Ten-ribbed Whelk (Chrysodomus decem- 

 costatus). 



