MOLLUSCA. 63 



spun yam gives way, and the rope pulls the head of the 

 dreg backwards, and disengages the teeth from the tangles 

 and stones. In transverse section the teeth form a trun- 

 cated ellipse round the central iron rod. 



The nomenclature adopted is that of Dr. Gwyn Jeffreys in 

 his valuable work on the British Mollusca ; and I am specially 

 indebted to him for his great courtesy in frequently aiding me 

 in doubtful cases, and also carefully investigating shell-debris 

 containing minute species, which otherwise might have been 

 overlooked. 



Class CONCHIFERA. 



Order Lamellibranchiata. 



Fam. 1. Anomiidae, Gray. 



Genus Anomia, L. 



Anomia ephippium, L. Jeffreys, Brit. Moll. ii. p. 31, 

 v. pi. 20. f. l,la-le. 



Not uncommon in the debris of the fishing-boats. 



Anomia patelliformis, L. Op. cit. ii. p. 34, v. pi. 20. f. 2, 2 a-2 c. 

 Common in the same region, as well as between tide-marks. 



Fam. 2. Ostreidae, Broderip. 



Genus Ostrea, L. 



Ostrea edulis, L. Op. cit. ii. p. 38, v. pi. 21. 



Living examples are rare. The " rock " variety with 

 purplish streaks, however, is occasionally found at the East 

 Rocks on the under surface of stones in pools near low water. 



Fam. 3. Pectuudee, Lamarck. 



Genus 1. Pecten, Pliny. 

 Pecten pusio, L. Op. cit. ii. p. 51, v. pi. 22. f. 1 & la. 

 Common ; the living specimens come from the deep water 



