402 THE ZOOLOGIST. 



mined foe of the Oyster. This species has a wide distribution 

 round our Kent and Essex shores, and even the deep water 

 beyond. It likewise reaches up the river estuaries and creeks 

 almost to the brackish water. Usually they are scattered hither 

 and thither of various sizes, but occasionally swarm in multi- 

 tudes, and literally cover some of the Oyster-grounds. 



It is not our intention to enter into the manner in which the 

 Starfish masters the Oyster and extracts the flesh. The latest 

 and most reliable authority on the subject, Dr. P. Schiemenz,* 

 shows from his observations and experiments that this is effected 

 by sheer force. Large Oysters, therefore, are comparatively 

 safe, the " brood " and " half-ware " permitting of easier extrac- 

 tion. The saving clause for the fishermen as respects the Star- 

 fish is that dredging for them has hitherto been a paying 

 concern. At otherwise intervals of slack times — the spring and 

 fall — the fishermen from various stations in Kent and Essex 

 dredge for them, and the catch is sold as manure to the farmers. 

 Moreover, it is asserted that the Starfish occasionally render a 

 benefit by thinning the numbers of the Mussels so detrimental 

 to the Oyster-beds (?). 



(b). The Mussels {Mytilus edidis) come under a different 

 category, namely, being only indirectly injurious to the welfare 

 of the Oyster communities. They in no way attack the Oyster 

 bodily, but they as effectually destroy "brood," "half-ware," 

 and the "ware" by their byssus or gelatinous threads (like 

 spiders' webs), entangling seaweeds, hydroid zoophytes, stray 

 cockles, broken fragments of shells, &c., and, above all, their 

 collecting of muddy and sandy material ; the heaping of these 

 latter stuffs around and over the Oyster simply means their 

 effectual destruction. Mussels notwithstanding are profitable 

 under certain conditions, but require cultivation as do Oysters. 



(c). As to the "Whelk-Tingle" or " Dog- Whelk " {Purpura 

 lapillus), their manner of attack on Oysters differs materially 

 from either of the preceding. They fix themselves by their 

 fleshy foot to the shell of the Oyster, and penetrate this by a 

 lingual rasp-like borer ; thence partake of the soft material of 

 the Oyster's body to its final detriment. There is, though, no 



* Mittheil. des Deutsch. Seefishver, Bd. xii. 1896; and Journ. Mar, 

 Biol. Assoc, n. s., vol. iv. p. 266. 



