I 



ON MOLLUSCA OP THE NORTH-EAST ATLANTIC, ETC. 135 



free. In the Canary Islands, at 12 to 15 fathoms, small and distorted, 

 imbedded in NuUipore. 



Crenella discors, Lin. — The largest British specimens I have obtained were 

 on the north coast of the Isle of Man, 10 fathoms. At Southampton 

 the pale green variety is frequent about low-water mark, adhering to the 

 leaves of Zostera marina. Near Tromsoe in Finmark it is most abundant 

 in beds covering the under surfaces of ledges of rock. Though reported 

 to be found in the Mediterranean I have not met with it south of the 

 British Channel, and believe it to have been confounded with C. costu- 

 lata by Mediterranean authors. 



Lithodomus caudigerus, Sotv The authors of the ' British MoUusca ' state 



that this is a South American species. It is frequent on the coast of 

 Asturias, Bay of Biscay, also at Faro iii the south of Portugal, at low 

 water burrowed in limestone rocks, but not found in the south of Spain 

 or Mediterranean, where its place is occupied by L. dactylus. I have 

 never obtained them together in any locality. 



Pecten Jacobseus, Lin Notwithstanding that this species is named after the 



Saint of Compostella, I have not been able to detect it on the coasts of 

 Galicia, or the north of Spain. 



Pecten Danicus, Chem. — This species would appear to have been formerly 

 much more abundant on the west coasts of Scotland than it is at pre- 

 sent; as the number of dead valves bears no proportion to that of living 

 specimens. It is met with throughout the Hebrides, but is most fre- 

 quent in Loch Fyne, the normal form in mud at about 70 fathoms, the 

 smaller and strongly striated variety upon hard ground at about 40 

 fathoms. It is extremely rare in Finmark, and I only met with small 

 dead specimens north of Drontheim. 



Pecten Islandicus, Milller. — Is doubtless extinct in the British seas, though 

 dead valves are frequent in the Firth of Clyde, Hebrides, Zetland, 

 Murray Frith and North Sea. In Norway, north of Drontheim, it is by 

 far the most abundant species of Pecten. 



Anomia ephippium, Lin. — Unlike most testaceous mollusca, which only re- 

 quire to be better known to be esteemed as delicacies for the table, the 

 Anomia is not to be eaten with impunity. On one occasion, having 

 sent my yacht round from a neighbouring port to that of Villaviciosa in 

 Asturias, where I purposed joining her after an excursion inland, my 

 crew, having been told that there wfere oysters in the harbour, determined 

 to dredge on their own account in my absence, and procured abundance 

 of the Anomia in large agglomerated masses. Seeing by the complexion 

 of the animals that they were not cof/tMon oysters, only one of the men 

 would venture upon eating them, and he suffered in consequence severe 

 vomiting, &e., with swelling of the abdometi, from which he did not 

 entirely recover for two or three days. 



The most beautiful yellow and purple varieties are found in the sunny 

 seas of the Mediterranean. 



Ostrea edulis, Lin. — Subject to much variation, tvhich has occasioned the 

 making of one or two questionable species, and rendered uncertain the 

 limits of its distribution. The common English or Welsh oyster is, how- 

 ever, certainly abundant and of excellent quality at Redondela, situated at 

 the head of Vigo Bay ; and I have likewise dredged it off Cape Trafalgar 

 in sand, and off Malaga in mud, but have not noticed it further eastward 

 in the Mediterranean. 



Chiton fascicularis, Lin. ; Chiton discrepans, Brown. — I must acknowledge 

 my inability to discriminate satisfactorily between these species. 



