268 riiocEEDiNCiS of thk mal.vcological society. 



Necera rostrafa, Spcnglcr. 



Necera ( Cmpidaria) Greeni, E. A. Smith. One example only. 

 This species was descrihcd in the Ann. and Mag. Nat. Hist., 

 Dec. 1889, from a sing-le specimen which was dred.2;('d off 

 the Irish coast in 1,000 fms. My specimen ilitfers sli<;htly 

 from the type, but I concur with Mr. E. A. Smith in 

 regarding them as the same species. 



Thracia convexa, Wood. 



Odostomia niietis, Jelfr., a large dead specimen. 



Rissoia elegantissima, Monterosato. 



It will be seen from the title of this paper that the new species now 

 described are claimed as belonging to the British fauna. 



Tlie question as to the limits within which species shall be considered 

 as British I discussed in a paper on the genus Fuaus, which appeared 

 in the Journal of Conchology, April 1890, and suggested that an 

 imaginary line drawn equidistant between the British Isles and tlic 

 territories of other States was the most logical limit. In ^lay of 

 the same year the Rev. Canon Norman contributed a paper upon 

 the same subject in the Ann. and Mag. Nat. Hist., in whi(;li he 

 advocated a bathymeti'ical limit of 1500 fms. in the West. This 

 would include the "Warm area" from which all the new species, 

 herein described, were obtained, with the exception of the Benlalhun. 

 Canon Norman, however, objects to the "Cold area" being included 

 — notwithstanding the fact of its being equally near to our coasts — 

 upon the ground that it " belongs more properly to the Arctic Ocean." 



If such a view be adopted, then the Bentalium (Bnigmaticuni has 

 no place in this paper; but with great respect I hold that such a view 

 is illogical and untenable, and maintain that the fauna living in the 

 seas surrounding our islands are British, whether the temy)erature of 

 the water in which they live be high or low. Surely this is the 

 principle which is acted upon in other branches of science ! The 

 Arctic or Alpine plants which still live on our table-lands and 

 mountains are included in tlic British flora, and are regarded as 

 imparting great interest to it ; and is not this a parallel case ? On 

 the one hand we have considerable elevations with climatic ct)nditions 

 suitable for the existence of an Arctic or Alpine flora, and on the 

 other hand we have considerable depths with low temperatures and 

 conditioiis suitable for the existence of an Arctic fauna. W liy sliould 

 the flora be accepted and the fauna be rejected? In recent geological 

 times all the fauna of our area were Arctic, and, as Sir Roljcrt Ball 

 says, " those Arctic conditions will inevitably recur." We are simply 

 living in an interregnum of these Ice Kings ; and a relatively small 

 geological "accident" — such as the elevation of the " Wyville-Thomson 

 Ridge," so that its summit were to become a terrestrial instead of a 

 subaqueous surface — would bring about semi-Arctic conditions over 

 our islands, and give Norway an ice-bound coast like those of 

 Labrador and Greenland; since it is the north-cast oceanic flow 

 which, as is well known, ameliorates the climate, and irapaits a more 

 .southern facies to the fauna than is due to our geographical position. 



