102 Moll, 
MOLLUSCA. 
Pecten grcenlandicus (Sow.). Structure of gills, see above in General 
Subject. 
Pecten fragilis (Jeffr., 1876), figured by the author, P. Z. S. 1879 
pi. xlv. fig. 1. 
Pecten multistriatus (Poli). Semi-distorted specimen ; Monterosato, 
Bull. Soc. mal. Ital. p. 215. 
Pecten pertenuis, sp. n., Dunker, J. de Oonch. xxvii. p. 215, pi. ix, fig. 3, 
locality unknown. 
Lima subovata (Jelfr., 1876) figured by the author, 1. c. pi. xlv. fig. 2, 
‘ Porcupine ’ Expedition. 
Lima elliptica (Jeffr.). Structure of gills, see above in General 
Subject. 
OSTREIDiE. 
Ostrea edulis {li.). A paper on the sexual relations of the Oyster by 
Gressy (Vannes : 1879, 8vo, 12 pp.), and another on the enemies and 
diseases of oysters in the basin of Arcachon by the brothers De Mon- 
taug4 in Act. Soc. L. Bord. xxxii. [1878] pp. 217-245, have not been 
seen by the Recorder. For abstract of the latter, see J. of Conch, ii. 
p. 364. The chief enemies are Carcinus mcBuas, Polybius henslowi^ and 
Asterias rubens ; the chief sickness an abnormal increase of fat, caused by 
the diminution of salt in the water. 
Ostrea virginica (Gmel.). W. K. Brooks states that he has never 
found a fertilized egg or embryo inside the mantle-cavity of the Ame- 
rican oyster, and comes to the conclusion that its eggs are fertilized out- 
side the body of the parent, and that during the period which the 
European oyster passes inside the mantle-cavity of the parent, the young 
American oyster swims at large in the open ocean ; he also gives a short 
sketch of the chief points in the development of the oyster. Am. J. Sci. 
(3) xviii. pp. 425-427. See also Science News, i. pp. 249-251. 
Placenta. The known species enumerated, with P.planicostata, sp. n., 
locality unknown ; Dunker, J. de Conch, xxvii. pp. 214 & 215, pi. ix. fig. 2, 
