96 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



included under Litorina Basterotii, Payr., wliicli removes any 

 doubt as to the species intended. 



For Littorina rudis (Maton), which must take the earlier name of 

 saxatilis, Olivi, we can use Littorivaga, Dall, 1918, in Proc. Biol. Soc. 

 Washington, xxxi, p. 137. The type is L. sitchana, Philippi, a form 

 scarcely distinct from L. groenlandica, Menke. 



In view of the small number of British species of Littorinidae, 

 it may be considered convenient to sink these names as subgenera 

 of Littorina ; but it may be pointed out that malacologically the 

 recognized genus Lacuna is closer to Neritoides than Littorivaga is 

 to Littorina. Accordingly I would group our species as under. 



Genus LITTORINA, Ferussac, 1822. Type: Turbo littoreus, L. 



1. LiTTOREA (L.), 1758. Normally, the angle of the spire is about 

 90°. Some northern forms have a more acute spire and more 

 elongated body whorl. The form hrevicula, Jeffreys, 1865 

 ( = conoidalis, Locard), is more globose, with a less produced spire, 

 which forms an angle of about 120°. The estuarine form paupercula, 

 Jefireys, is scarcely distinct from hrevicula. 



Genus LITTORIVAGA, Dall, 1918. Type : L. sitchana, Philippi. 



2. Saxatilis (Olivi), 1792 (as Turbo). The variation of this 

 polymorphous species has been fully discussed and beautifully 

 illustrated by Dautzenberg and Fischer in Res. Camp. Sci. Monaco, 

 xxxvii, 1912, pp. 187-201. Their arrangement is convincing, and is 



' quoted here for convenience of reference : — - 



(a) Subsp. saxatilis, typica, with v. lugubris, D. & F., and v. 

 nervillei, D. & F. 



(&) Subsp. tenebrosa, Mont., 1803, with v. elata, D. & F., and v. 

 ■similis, Jeff. 



(c) ^vibs^.jugosa, Mont., 1803, with v. bynei, D. & F. 



{d) Subsp. patula, Thorpe, 1844, with v. attenuata, D. & F. 



(e) Subsp. nigrolineata, Gray, 1839, with v. compressa, Jefi., 

 and V. matoni, D. & F. 



(/) Subsp. rudis, Maton, 1797, with v. globosa, Jeff., and v. 

 rudissima. Bean. 



{g) Subsp. groenlandica, Menke, 1830. 



The form tenebrosa can hardly be ranked as a distinct species, 

 since there are intermediate forms connecting with jugosa through 

 similis, while other examples approach saxatilis and even rudis. 

 The northern race groenlandica is certainly to be included in this 

 species, and I have taken a series of graded forms in Orkney ranging 

 from similis at ordinary high- water through jugosa above high- 

 water to groenlandica, which may be found even 40 or 5.0 feet higher 

 .still, as described by Dacie in Journ. of Conch., xv, 1917, p. 179, 

 where he gives this form the name of alticola, which should be 

 rejected as a synonym of groenlandica, 



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