1879.] 'lightning' AND 'porcupine' EXPEDITIONS. 575 



and Bay of Fundy in the N. Atlantic and to Japan in the N. Pacific ; 

 5-150 fms. 



Fossil. Post-tertiary or "glacial." Scandinavia, Great Britain 

 and Ireland, Labrador and Canada ; 0-1 30 ft. 



The most common synonym is L. caudata, Donovan. 



3. Leda fragilis, Chemnitz. 



Area fragilis, Chem. Conch. -Cab. vii. p. 199, t. 55. f. 546. 



'Porcupine' Exp. 1870 : Atl. St. 10, Vigo B., 13, Setubal B., off 

 C. Espichel, 22, 27-30, 3b", Tangier B. ; Med. 45, Cartagena B., 

 50, 54, 55, Benzert Road, Rasel Amoush, Adventure Bank, off 

 Rinaldo's Chair. Abundant in the Mediterranean cruize. 



Some specimens are more closely striated than others. 



Distribution. Atlantic coasts of France and Lusitania from Ar- 

 cachon to C. Trafalgar, throughout the Mediterranean to the y£gean, 

 Adriatic, G. of Florida ; 20-185 fms. 



Fossil. Miocene and Pliocene. Belgium, N.W. Germany, Vienna 

 Basin, Transylvania, Switzerland, S.W. & S. France, Italy, Greece, 

 and Rhodes. 



This species was unmistakably described and figured by Chemnitz ; 

 and his specific name fragilis was adopted by that painstaking 

 naturalist Dillwyn, and since by Homes and Hidalgo, although the 

 last considered it distinct from the Nucula commutata of Philippi, 

 which is certainly the present species. Risso, Chiereghiui, and 

 Eichwald gave it other names. 



4. Leda pella, Linne. 



Area pella, L. S. N. p. 1141. 



A. interrupta, Poli, Test. utr. Sic. ii. t. 25. f. 4, 5. 



'Porcupine' Exp. 1870: Med. St. 50, 55, G. of Bona, Benzert 

 Road, G. of Tunis, Adventure Bank. Varies in the sculpture, like 

 L. fragilis. 



Distribution. Atlantic coasts of Spain and Portugal, throughout 

 the Mediterranean to the Sea of Marmora, Adriatic, Japan ; 

 4-100 fms. 



Fossil. Miocene and Pliocene. Antwerp Crag, Poland, Vienna 

 Basin, Switzerland, S.W. France, Italy, Greece, Rhodes and 

 Cyprus. 



The principal synonyms are Area interrupta of Poli and Nucula 

 emarginata of Payiaudeau. 



1/ 5. Leda arctica, Gray. 



Nucula arctica, Gray in Suppl. App. Parry's first voyage, p. eeli 

 (1824). 



Portlandia arctica, G. O. Sars, Moll. reg. arct. Norv. p. 37, t. 4. 

 f. 7a-h. 



L. arctica, B. C. ii. p. 158. 

 Porcupine' Exp. 18G9 : St. Loch Torridon. A fine and perfect 

 specimen and two valves, all apparently subfossil. 



