| OCR Text |
Show 1886.] IN MELEAGRINA MARGARITIFERA. 177 his partners on the N.W. coast of Australia, and has submitted many shells to m e which had been attacked by lithodomous Mol-lusca, or by worms and the burrows of Cliona. " Some of these I have now the pleasure to exhibit. I have, moreover, to-day been permitted by Prof. Flower to examine a still more interesting specimen which he has just received from Henry Willett, Esq., F.G.S., of Arnold House, Brighton. " It is that of a specimen of Pinnotheres which has been entombed in a cyst of pearl by a living pearl-mussel, into the shell of which he had ventured to intrude. " It seems extraordinary and beyond belief that the Meleagrina should of all the Conchifera be the one to resent the commensalism of the Pea-crab, which has been known since the days of Cicero, Pliny, Oppian, and Aristotle to inhabit the shell of the Pinna and the Oyster, and has been recorded from Astarte, Pectunculus, and at least some half-dozen other bivalves, with whom it appears to live on the most friendly terms. " It is the females, however, which constantly reside within the shells of the Conchifera, whilst the males are said to avail themselves of favourable opportunities to visit the females in their retirement. "Whether or not in this case the unlucky male intruded himself upon Meleagrina at an unfavourable period, and finding no female Pinnotheres, penetrated so far beneath the mantle of the Pearl-mussel as to be unable to retreat, one thing is quite clear, namely that the Meleagrina entombed the intruder in a cyst of pearl from which the clever pearl-button maker alone liberated him. " There is a large series of Pinnotheres'm the Museum: the one from Australia is referred to P. orientalis, but as these are all females comparison is useless. These are from shells of Pinna, Donax, and Pectunculus. There are others from Broken Bay. " Prof. Dana, U.S. Expl. Expedition, 1852, part i. text, pp. 380- 381, and Atlas, pi. 24. fig. 3, describes a species under the name of P. obesa from Fiji Islands. The male, however, is said to be slightly broader than long, and the eyes (which in the adult female are quite hidden beneath the overreaching and protuberant carapace) can be seen in the upper view, and the front of the carapace is emarginated by the orbits. (Size 4| lines long, and 6^ broad.) " Mr. Willett's specimen is slightly longer than broad, and in size agrees very nearly with the male of P. pisum, which was formerly described by Leach as P. latreillei." The following papers were read :- |
