11 



ON A NEW AND REMARKABLE SUB-SPECIES OF LIMNMA 

 PEREGER, MtJLL., FROM ICELAND. 



By H. B. Peeston, F.Z.S. 



Read 9th January, 2914. 



The series of specimens upon which the present sub-species is based 

 were handed to rue for examination by Mr. F. H. Sikes, in whose 

 lionour I have much pleasure in naming it, and who collected them 

 in August, 1912, during his recent extensive travels in Iceland. As 

 far as the collector is aware, they occur only in Rautharvatn or ' red 

 lake', which, he informs me, is "little more than a tarn among 

 a desert of red earth " situated between Reykjavik and Thingvellir. 



Mr. Sikes paid three visits to this lake, and on each occasion took 

 specimens on some submerged rocks which appear to he their only 

 habitat. The only other species of mollusc represented in Rautharvatn 

 is Pisidium lilljeborgii, Clessin,' which attains a large size, and the 

 collector has pointed out to me at some length the almost exact 

 similarity of the circumstances under which the present Limnma was 



collected to those in which he had previously taken the Irisli 

 L. involuta, Thomp.,- in Lough Crincaiim, co. Kerry, whieli it would 

 seem occurs also in that lake with but one molluscan co-inhabitant, 

 but which in this latter instance proved to be Pisidium s]i. 



After careful examination of the very long series of L. pereger in 

 Mr. Hikes' collection I have been unahle to find any form to which 

 the present sub-species may be profitably compared, its nearest ally 

 being ovata, Draparnaud,^ though from this it differs appreciably in 

 many ways, among the more noteworthy being its more oblong shape, 

 extremely thin texture, and much less exserted spire. 



Mr. Sikes further informs me that the animals are of a very pale 

 colour and tlie shell so fragile that he broke many specimens in 

 attempting to extract them. 



^ Clessin in Esmark & Hover, Malak. Blatt., N.F., viii, p. 119. 



" Ann. Mag. Nat. Hist., London, vol. v, p. 22, 1840. 



■'• Hist. Nat. moll. terr. fluv. France, p. 52, \A. ii, figs. 30-1. 



