88 TEE ZOOLOGIST. 



hole had been bored by a carnivorous gastropod during the life- 

 time of the Whelk (fig. 1, b, c). About half of a large whelk 

 shell, which was broken up and thrown into the tank on 

 August 2nd, was eaten by the Sea-Urchins by the 9th, certain 

 of the harder parts of the shell, however, such as the columella 

 and shell-siphon, being left uneaten until the present. A Sea- 

 Urchin will seize a living Periwinkle, or an empty periwinkle 

 shell, and hold it in such a way that the thin edge of the lip 

 of the shell lies conveniently under the mouth of the Sea-Urchin, 

 and the latter will then proceed to snap off tiny pieces along 

 the lip. Two or three Periwinkles which had evidently been 

 treated in this fashion were at one time to be seen crawling 

 about the aquarium ; but, of course, it is only in the rare case of 

 a mollusc being seized when it is close to the glass that the 

 process can actually be watched. 



The shells of several living Edible Mussels have been 

 damaged by the Sea-Urchins, and in all cases they were bitten 

 at their hinder ends (fig. 1, c). On several occasions a Sea- 

 Urchin has gnawed the valves of a Mussel in such a way that 

 a gap has been made between them ; and through this gap 

 the thick edge of the retracted mantle, where it forms the 

 boundaries of the inhalent and exhalent apertures, could be 

 seen. In at least two cases a large Common Starfish (Asterias 

 rubens), attracted by the exposed soft parts of the Mussel, 

 has attacked and opened the mollusc. This matter may deserve 

 further investigation from the bionomic and economic points of 

 view, as it is known that a Starfish can throw its stomach 

 through a comparatively narrow aperture.* 



Echinodermata. — Eichelbaum found the remains of echino- 

 derms in ten examples. These remains were those of asteroids, 

 ophiuroids, and echinoids, and they included shell fragments, 

 spines, and pedicellarise. 



* M. Hesse (" Note sur les Motifs qui determinent les Oursins a se 

 creuser dans les Eochers," 'Ann. d. Sc. Natur., T. vii, series 5, 1S67, 

 p. 259) mentions that Echinus miliaris will bore into oyster shells. 

 K. Mobius (" Uber die Thiere der Schleswig-Holsteinschen Austernbanke," 

 ' Sitzungsb. Konig. Preuss. Akad. Wissen. Berlin,' vol. viii, 1893, p. 81) says 

 that he is doubtful whether it attacks living Oysters. E. J. Allen (" On the 

 Fauna and Bottom Deposits, etc.," 'Jour. Mar. Biol. Assoc.,' vol. v, 

 (N. S.), 1897-9, p. 474) says that it does great damage on oyster-banks. 



