CLATHUEELLA PURPUREA. 233 



Great Britain rather than on the east. Prof. Brjsrgger has pointed out that a few of 

 them, as, for example, G. jmrjnirea and 0. Lenfroyi, occur in certain zones of the later 

 Pleistocene deposits of the Christiania region, viz., in those he has called the 

 Tapes-banks, the Isocardia-clays and the Scrobicularia-clays, associated with other 

 characteristic Lusitanian shells, and Dr. 0yen has found similar species near 

 Trondhjem in strata of like age,^ indicating the existence of a milder climate at a 

 certain stage of the post-glacial period than that of the present day in the same 

 region. The colonies of such southern species now found living far to the north 

 of their general habitat may be probably survivors of this immigration which 

 appears to have taken place subsequently to the final melting of the great ice- 

 sheets. 



The existence of this group of southern shells in the Waltonian Crag, moreover, 

 supports the view already taken that there is a closer connection between it and 

 the Coralline Crag with its strong Mediterranean afiinities than has been hitherto 

 suspected. They are fairly abundant in the Waltonian deposits. I have in my 

 own collection from Oakley, for example, more than fifty specimens of the most 

 characteristic species, but have no reason to think they are equally abundant at 

 the later horizons of the Red Crag. 



C. purpurea was not recorded by Wood as a Crag shell, though, judging from 

 his figure of Glavntula PhUberti {op. cit. ),t\ie specimen described by him under that 

 name seems to belong to the former species ; it has, as he remarked, the strong 

 internal denticulation of the outer lip, and it presents the regular and wavy spiral 

 sculpture and clathrate ornamentation distinctive of (). purpurea} I have a 

 specimen of a small variety, described below as var. minor, and one or two others 

 not sufficiently perfect for illustration, from Oakley. As it has been reported from 

 time to time from the Crag, it seems desirable to figure a Recent shell from 

 St. Malo which may be regarded as typical, and may be useful to collectors for 

 the purpose of comparison, 



G. purpurea was found by Mr. A. Bell in a collection of Upper Pliocene shells 

 from Biot near Antibes sent him for identification. It occurs also, according to 

 Sign. Cerulli-Irelli, in the Upper Pliocene (Astiano) of Monte Mario, and is recorded 

 by Bellardi from deposits of similar age in Northern Italy. It was met with in a 

 Holocene deposit at Portrush in Antrim, discovered by the late James Smith of 

 Jordanhill and afterwards described by Mr. A. Bell in the Report of the Leeds 

 meeting of the British Association for 1890, p. 419. 



i 0yen, Kgl.Norske Vid. Selsk. Skrift. [9], p. 148, 1910. 



2 The specimeu of G. ])urinirea from Oakley (fig. 16) has the outer lip too imperfect to show the 

 internal denticulation. The form and sculpture, however, are those of the present species. 



30 



