5882 



Mollusks. 



by the possibility which always exists of the species in question yet 

 lingering alive (as indeed we have seen in the case of Leda pygmaea), 

 in some limited tract or boreal patch in our seas. Until, however, 

 such is proved to be the case, we cannot admit well-known and cha- 

 racteristic drift species into our list of living forms, and in this cate- 

 gory we must place Leda oblonga [Nucula ohlonya, Brown, 111. Conch. 

 G. B. p. 84, pi. 33) and Leda truncata {Nucula iruncata, loc. cit. p. 

 84, pi. 33), both of which, however, are still found living in Arctic 

 regions."— i^. H. vol. ii. p. 232, 233. 



*Arca lactea. Two or three were taken some years since near the 

 Corriegills, Arran, by Dr. Landsborough and Major Martin ; but 

 John Kelso (the boatman whom I would recommend conchologists 

 to employ at Lamlash), who accurately described the shells, tells me 

 that, though he has repeatedly dredged there since expressly for it, it 

 has not since been met with. 



*Pectunculus glycimeris {Pectunculus pilosus). Very local. Ar- 

 ran, Ayr, Smith. It occurs to the north-east of Holy Island in deep 

 water, and there is also a series in the British Museum from the 

 Island of Bute. 



« 



Fam. XIX. Aviculacece. 



Pinna pectinata {Pintta ingens). " The Pinna ingens has only 

 once, that I know of, been got at Arran." — Lands. Excurs. p. 60. 



Fam. XX. Ostrceadce. 



Lima subauriculata. I have met with single valves of this shell in 

 Lamlash Bay, where Dr. Landsborough has also taken'it. 



„ Loscombii {Lima fragilis). A single valve near the Tan 

 Buoy, Cumbrae. Bute, Smith ; Lamlash, La^idshorough. 



„ trians {Lima tenera, injiata and vitrina). This is one of 

 the most interesting Mollusca of the Clyde, and is abundant almost 

 everywhere in the district among nullipore. Kelso tells me that when 

 first Dr. Landsborough began to dredge at Lamlash, Lima trians 

 could only be found in one confined spot in the Bay : it is now to be 

 met with in all parts. Doubtless dredging has been the chief 

 means in effecting this diffusion, since in overhauling the nullipore 

 young specimens would, as the boat moved on, be thrown overboard 

 here and there, and become the parents of a numerous progeny. 

 Nothing can be more lovely than the animal of Lima trians ; its 

 thousand delicate and beautifully ringed vermilion tentacula, each 

 maintaining, as it were, a life independent of its neighbour's, turning 



