>^12 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [JuUC t , 



A. crebricostata, B. C. ii. p. 31!) : v. p. 183 : G.O. Sars, Moll. reg. 

 arct. Norv. t. 5. f, 7, a, b, 



'Porcupine' Exp. 1869 : St. The Minch (semifossil). 



Distribution. Arctic seas from Tromso northwards, Siberian coast, 

 N.E. America from Maine northwards, 'Fox' Exp., 'Valorous' 

 Exp., Norwegian arctic Exp., Dutch arctic Exp. ; 5-500 fms. 



Fossil. Post-tertiary: Great Britain, Scandinavia, Siberia; 10- 

 1360 ft. 



Syn. Crassina depressa, Brown, A. crebricostata, Forbes, A. cre- 

 brilirata, S. Wood (young), y±. richardsoni, Reeve, A. lens, Stimpson 

 MS. 



May be known by its depressed and triangular shape and its 

 numerous ribs ; but I have specimens which seem to unite it with A. 

 sulcata. The typical form is smaller, inclined to oblong, and more 

 convex. Variable to some extent. Of two fossil valves from Brid- 

 lington of the same size one is plain edged, and the other has the 

 inner margin notched. 



•y 4. ASTARTE COMPRESSA, MoUtagU. 



Venus compressa, Mont. Test. Brit. Suppl. p. 43, t. 26. f. 1. 

 . A. compressa, B. C. ii. p. 315 ; v. p. 183, pi. xxxvii. f. 3, 4. 



'Porcupine' Exp. 1869 : St. Loch Torridon (var. warhami, semi- 

 fossil). 1870: C. Sagres (var. semistriala, valves). 



Distribution. N. Atlantic from Spitzbergen and Novaya Zemblia 

 to the Dogger Bank and New England, Vancouver I. (P. Carpenter, 

 as A. comjyacta) ? The typical form is arctic, Scandinavian, Hebri- 

 dean, and N. American ; the variety globosa is also arctic ; var. striata 

 is arctic and northern, but reaches the Yorkshire coast. 3-2000 fms. 



Fossil. Upper Tertiaries, and more especially Post-tertiary ; 

 Siberia, Scandinavia, G. Britain and Ireland, N.E. America (mostly 

 var. striata), Nice {Risso, as Cyprina niontagui) 1 ; 0-1360 ft. 



Not less variable than A. sulcata, and consequently having many 

 sj'nonyms. The typical or smooth form is Nicania banksii of 

 Leach. My variety globosa is not Moller's species of that name, 

 but agrees with a specimen from the collection of the late Mr. Albany 

 Hancock, which was named by him A. warhami. The A. sulcata 

 of Gould (fig. 45) represents this last variety. 



^ 5. AsTARTE TRIANGULARIS, MontagU. 



Mactra triangularis, ]\Iont. Test. Brit. p. 90, t. 3. f. 5. 



A. triangularis, B. C. ii. p. 318 ; v. p. 183, pi. xxxvii. f. 5. 



'Porcupine' Exp. 1870: Atl. St. Vigo B., C. Sagres, 26, 36; 

 Med. Algesiras B., Cartagena B., 50, Benzert Road, Adventure 

 Bank (var. subtrigona.) 



Distribution. Shetland to G. Egina, Adriatic, Canaries (var. par- 

 vula) ; 0-205 fms. 



Fossil. Upper Tertiaries : British Isles, Belgium, Vienna Basin, 

 S.W. France, Italy. Post-tertiary : Norway, Calabria. 



Synonyms several. " Gregarious in fine shelly sand at low water 



