55G DR, GWYN JEFFREYS ON THE MOLLUSCA OF THE [June 17, 



Family III. Sfondylid^:. 



Spondylus gussoni, O. G. Costa. 



S. gussonii, O. G. Costa, Cat. Sist. p. xlii : Philippi, Moll. Sic. i. 

 p. 87, t. v. f. 16. 



'Porcupine' Exp/1 870: Atl. St. 16, 24, 25; Med. 45, Capo de 

 Gata, 58. 



Distribution. Mediterranean, Adriatic, and iEgean ; 40-120 fms. 



Fossil. Pliocene. Metz, Biot, Sicily. 



S. gcederopus did not occur ; and it will be seen that many other 

 equally common shells were not procured during any of these 

 Expeditions. 



Family IV. Pectinid^e. 



1. Pecten pusio, Linne. 



Oslrea pusio, L. S. N. 1146. 



P. pusio, B. C. ii. p. 51 ; v. p. 166, pi. xxii. f. 1. 



'Lightning' Exp.: St. 4. 



'Porcupine' Exp. 1869 : 2. 1870: Atl. Vigo B., 36 (Hinnites 

 form), Tangier B. ; Med. Capo de Gata, 55. 



Distribution. Faroe Isles to Morocco and the Mediterranean, 

 Adriatic, iEgean, Madeira, Canaries, Azores, and S. Africa; 0-180 fms. 



Fossil. Pliocene and Post-tertiary. Scandinavia, Great Britain 

 and Ireland, Belgium, Transylvania, S. France, Algiers, Italy, and 

 Rhodes; 0-130 ft. 



Several synonyms, including P. distortus of Da Costa and P. mul- 

 tistriatus of Poli. 



I have here endeavoured, as on former occasions, to arrange the 

 species in their natural sequence, so as to show their relative affinity. 



In the ' Porcupine ' Expedition of 1870, I dredged at Station 9 

 (509 fms.) a fragment of a Pecten, apparently allied to P. pusio, 

 but representing a shell about an inch and a half in length, and at 

 Station 16 (994 fms.) a very small valve of the same species. It 

 has numerous ribs, which are alternately larger and smaller, and 

 covered with numerous close-set prickles or imbricated scales. I 

 would provisionally name this species senticosus. 



2. Pecten varius, LinnS. 



Ostrea varia, L. S. N. p. 1146. 



P. varius, B. C. ii. p. 53 ; v. p. 166, pi. xxii. f. 2. 



♦Porcupine' Exp. 1869 : Loch Foyle. 1870 : Atl. Tangier B. 



Distribution. Christiansund to Egypt and Gulf of Suez ; 0-55 fms. 



Fossil. Miocene. Turin. Pliocene and Post-tertiary. Scandinavia, 

 Great Britain and Ireland, S. France, Italy, Algeria, Morea, and 

 Rhodes; 0-150 ft. 



3. Pecten islandicus, Midler. 



P. islandicus, Mull. Zool. Dan. Prodr. p. 248 : G. O. Sars, 

 Moll. reg. arct. Norv. t. 2. f. 2. 



'Porcupine' Exp. 1869: St. 25 (fragments; semifossil ?). 



