946 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [NoV. 29, 



Synonyms numerous. The shell referred to by Gmehn for his 

 Mya membranacea from the figure in OlafsenandPovelsen's 'Voyage 

 to'lceland' (t. xi. f. 10) is apparently the young of Mija truncata. 

 That which Miiller described and Gmelin named also Mya membra- 

 nacea was probably Lyonsia norveyica. 



i 2. Mya binghami, Turton. 



Sphenia binyhami, Turt. Dith. p. 36, t. 3. f. 4, 5, and t. 19. f. 3. 



M. binghami, B. C. iii. p. 70 ; v. p. 192, pi. 1. f. 3. 



' Porcupine' Exp. 1870 : Atl. St. Tangier B, 



Distribution. Loffodeu Is. to Bay of Naples and Tunis ; 4^-40 fms. 



Fossil. Miocene : Lapugy iu Transylvania. Pliocene : Coral- 

 line and Bed Crag. Post-tertiary : Larne, co. Antrim. 



The genus Sphenia of Turton is a mere synonym of Mya. All 

 the characters given by him to distinguish it from Mya are the same 

 in both. His (S. swainsoni is the young of J/, truncata. 



Family XXII. Saxicavid^e. 

 ^ Panopea plicata, Montagu. 



Mytilus plicatus, Mont. Test. Brit. Suppl. p. 70. 



P. plicata, B. C. iii. p. 7o, pi. iii. f . 2 ; v. p. 192, pi. li. f. 1. 



•Porcupine' Exp. 1869 : St. 9, 18, Donegal B. 1870: Atl. Vigo 

 B,, 24 ; Med. Adventure Bank. 



Distribution. Loifoden Is. to Algiers and Sicily, Canaries, Korea ; 

 5-628 fms. 



Fossil. Miocene: Cassel. Pliocene: Coralline and Red Crag, 

 Belgium, Italy. Post-tertiary : Belfast. 



There are several generic and specific synonyms. 



Saxicava rugosa, Linne. 



Mytilus rugosus, L. S. N. p. 1156. 



S. rugosa, B. C. iii. p. 81, pi. iii. f. 3; v. p. 192, pi. li. f. 3, 4. 



'Lightning' Exp. : St. 1, 2, 4, 5. 



'Porcupine ' Exp. 1869 : St. 1, 2, 6.. 9, 10, 14, 17, 23«, 35, 62, 

 65 (and semifossil valve of arctic or glacial type). 1870 : Atl. 3, 

 3a, 9, 10, 12, Vigo B., 13, Setubal B., 26-28, 36; Med. G. Bona, 

 Basel Amoush, G. Tunis, Adventure Bank. 



Distribution. Type and variety arctica, apparently everywhere in 

 every sea throughout the world, at every depth from low water to 

 1622 fms. 



Fossil. Miocene, Pliocene, and Post-tertiary : nearly every part 

 of Europe, northern Asia, and North America ; 0-1360 ft. 



Tills ubiquitous and variable shell has received more than twenty 

 names in respect of its genus and species. Linne placed the type 

 and some of the varieties in Mytilus, Solen, and Mya. The date 

 of publication is the same for Mytilus rugosus and Mya arctica ; but 

 the former specific name is more generally used. I have therefore 

 treated the latter name as varietal. 



