ON MOLL.USCA OF THE NORTH-EAST ATLANTIC, ETC. 



137 



the Mediterranean ; in latter district it undergoes considerable variation 

 in colour. 



Fusus gracilis, Da Costa. — Notwithstanding the opinion of Middendorf, 

 adopted by Forbes and Hanley, that this is only a variety of F. Islandicus 

 of Chemnitz, I am quite satisfied of the contrary after obtaining the 

 true Fusus Islandicus in the neighbourhood of the North Cape, It 

 was from about 100 fathoms, and measured 4-^ inches in length, while 

 adult specimens of Fusus gracilis from the same locality did not measure 

 more than 2^ inches in length. 



Spirula Feronii, Lam. — This shell, possessing a peculiar aptitude for floating 

 on the surface of the sea when dead, is liable to be drifted to localities 

 very remote from its native habitat. A chance specimen has occasion- 

 ally been picked up on the shores of Britain ; on the south coast of the 

 Bay of Biscay it is still rare, is more frequent at Gibraltar and Malaga, 

 and abundant in the Canary Islands. I am not aware of its having been 

 found in the eastern Mediterranean. 



The following Table M'ill be of assistance in a comparison of the Geographi- 

 cal range of the species and the number obtained in each of the districts. 



Species. 





2S 



Acephala. 



Xylophaga, Turton. 



dorsalis, Turton 



Pholas, Lin. 



dactylus, Lin 



parva, Lam 



crispata, Lin 



Candida, Lin 



Pholadidea, Leach. 



papyracea, Solander .. 

 Clavagella, Lam. 



sp. ined 



Gastrochsena, Spengler. 



modiolina, Lam 



cuneiformis. Lam 



Pandora, Lin. 



rostrata, Lam 



obtusa, Leaeh 



Lyonsia, Turton. 



Norvegica, Chem 



arenosa, Moller 



Thracia, Leach. 



phaseolina, iam 



villosiuscula, Macyill. 

 pubesceiis, Pulteney . 



convexa, Wood 



distorta, Mont 



