128 PROCEEDINGS OP THE GEOLOGICAl SOCIETy. 



the opportunity of recording the opinion of another distinguished 

 naturalist, Mr. Gwyn Jeffreys, who has made European conchology 

 his especial study, and has particularly worked out the deep-sea fauna 

 with a view to a comparison with fossil species upon this question. 

 We have visited the Crag district together ; and he has examined aU 

 the more important Crag collections, while with the same object in 

 view he has also extended his researches to the Pliocene collections 

 of the Continent. The special results of his elaborate inquiry will 

 be found in the tabular list, pp. 137-146. The list of Coralline- 

 Crag Mollusca so revised gives a total of 316 species, of which Mr. 

 Jeffreys considers 264 to be Kving and 52 extinct, thus giving a per- 

 centage of 84 recent, and apparently only of 16 extinct species *. 



Of these 265 living species of Mollusca, Mr. Jeffreys has deter- 

 mined 185 to be still living in the British seas, and 80 to be species 

 living now only in extra-British seas. Of the latter, 14 species live 

 in northern seas only, 65 in southern only, and 1 lives in both nor- 

 thern and southern seas. Dividing the living species into zoological 

 provinces, I find their distribution is as under : — 



Bivalves. Univalves. Total. Peculiar. 



Arctic 19 



Scandinavian 75 



British 101 



West European 90 



Mediterranean 103 



Mid-Atlantic 49 



Deep Atlantic 41 



Special localities.^N orth America, 

 Mexico, 1 ; Japan, 3. 



Of the 5 species of Brachiopods in the Coralline Crag, 1 only is 

 extinct. Two are British species with an extensive range. Mr. 

 Gwyn Jeffreys has dredged the Argiope cistellula in from 20 to 80 

 fathoms water ; and the TerehratuUna caput-serpentis ranges from 

 the shore to 632 fathoms. The Discina atlantka has been dredged 

 in the deep Atlantic (7560-13,500 feet). The Lingula Dumortieri 

 has been dredged in the seas of Japan. As a rule, Brachiopoda may 

 be considered to indicate deep water. 



Bryozoa. — According to Mr. Busk, there are not less than 95 species 

 of Bryozoa found in the Coralline Crag ; 30 of these species are now 

 living, and 65 are extinct. Of the former, 26 still inhabit the British 

 seas ; and of the other four, 3 are found on the west coast of Africa 

 and at Madeira, and 1 is probably living in the Australian seas. Of the 

 26 British species, 9 have a southern range, some as far as Patagonia 

 and the Falkland Islands. There is one remarkable exception to 

 this southern character ; the Retepora Beaniana has been found on 

 the coast of Norway by Mr. M' Andrew, and in the Arctic sea by Sir 

 Edward Belcher. Mr, Busk considers it to be a wholly northern 



* Whether or not the greater number of shells will prove to be living, re- 

 mains for future research ; but certainly the conclusions of Mr. Jeffreys are in 

 harmony with the inquiries of Sir Cliarles Lyell, which have shown a smaller 

 percentage of extinct species in the Coralline Crag of late than formerly. 



15 . 



34 ... 



... 2 



60 . 



135 ..., 



... 



84 . 



185 .... 



,.. 2 



81 . 



171 .... 



.. 1 



97 . 



..... 200 .... 



.. 17 



60 ., 



99 ... 



.. 4 



51 ., 



92 .... 



.. 10 



1 : Africa, 4 : 



West Indies, 



2 ; Gulf of 



