562 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [June 1 7, 



inside sculpture. P. alaskensis of Dall, from Port Etches in the 

 North Pacific is allied to the present species ; hut it differs not only 

 in its much greater size, but also in the external sculpture, and in 

 the number of internal ribs, which are from 17 to 21 in A.fene- 

 stratum and from 31 to 35 in A. alaskense. 



2. Amussium hoskynsi, Forbes. 



Pecten hosfajnsi, Forb. Rep. Brit. Assoc. 1843, p. 192; G. O. 

 Sars, Moll. reg. arct. Norv. p. 20, t. 2. f. 1, 1 a-e. 



'Porcupine' Exp. 1869: St. 23, 39,65. 18/0 : Atl. 1, 2, 3, 

 24-30 ; Med. 55. In specimens from the last-named station (1456 

 fms.) the upper valve is smooth or nearly so, and the inside ribs 

 are entirely or partly absent. The microscopic sculpture of the 

 young is very beautiful. 



Distribution. Novaya Zemblia, off Spitzbergen and Jan Mayen 

 I., E. coast of Greenland, Norway, Sicily, iEgean, and off the Azores ; 

 30-650 fms. Arctic specimens are very large, measuring fully three 

 quarters of an inch. 



Fossil. Pliocene and Post-tertiary. Norway, Calabria, and Sicily. 



Syn. Pecten fimbriatus and P. antiquatus (upper and lower 

 valves), Philippi, and P. imbrifer, Loveu. The sculpture is variable, 

 although the upper valve is usually more or less covered lengthwise 

 with rows of pustules or frills, and the lower valve is closely striated 

 in the line of growth. The full number of internal ribs is 1 7. 

 P. pustulosus of Verrill, from the coast of New England, is probably 

 this species ; but I have not been able to see more than a single 

 specimen, which was smooth inside. 



3. Amussium lucidum, Jeffreys. 



Pleuronectia lucida (Jeffr.), Wyville-Thomson, Depths of the Sea, 

 p. 464, f. 78. 



A. lucidum, Jeffr., in Ann. & Mag. Nat. Hist. Nov. 1876, p. 425. 

 'Porcupine' Exp. 1869: St. 39, 41, 420. 1870: Atl. 3a, 16, 



17, 17a. 



Distribution. ' Valorous ' Exp., ' Challenger' Exp. (west of Azores 

 and Pernambuco), Gulf of Mexico ; 156-1450 fms. 



Var. striata. Upper valve marked by fine, close-set, and more 

 or less distinct longitudinal stria? ; 'Porcupine' Exp. 1870, Atl., St. 

 1 7a ; * Challenger' Exp. (off Marion I.), 1375 fms. The number of 

 inside ribs varies from 9 to 15. 



A. Shell equilateral, completely closed. Limatula. 



1. Lima sarsii, Loven. > 



Limea sarsii, Lov. Ind. Moll. Scand. p. 32. 

 Lima sarsii, B. C. ii. p. 78 ; v. p. 169, pi. xxv. f. 1. 

 •' Lightning' Exp. : St. 2, 5. 



• Porcupine' Exp. 1869 : St. 15, 23a, 65. 1870 : Atl. 1, 2, 3, 6, 

 24, 26-30 ; Med. 55, Adventure Bank. 



