PEARL OYSTER PARASITES, ETC. 341 



to, another small crab {Pinnotheres maculattis Say) is sometimes foniul 

 ill the common mussel {Mytilns edulis), and the large scallop {Pectcn 

 tcnuicostafus) before mentioned. It is doubtful, however, whether these 

 crabs are really parasites or only commensals, though probably the 

 former. 



Before the Zoological Society (London, April 6, 186G), Dr. H. Wood- 

 ward exhibited specimens of animals, commensal or parasitic, in the pearl 

 mussels of Australia. Among these was "a specimen of Pinnotheres 

 which has been entom'oed in a cyst of pearl by a living pearl-mussel," 

 etc. 



He further remarked : '' It seems extraordinary and beyond belief 

 that the Mclcagrina should of all the Couchifera 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 Asiartc, Peetunculus, aiul at 

 least some half-dozen other bivalves, with whom it a})pears to livc^ ou 

 the most friendly terms. 



" It is the females, however, which constantly reside within the shells 

 of the Couchifera, whilst the males are said to avail themselves of favor, 

 able opportunities to visit the females in their retirement. 



" Whether or not in this case the unlucky male intruded himself upon 

 Mcleagrina at an unfavorable period, and, tinding no female Pinnotheres, 

 penetrated so far beneath the mantle of the pearl-mussel as to be un- 

 able to retreat, one thing is quite clear, namely, that the Meleafjrina 

 entombed the intruder in a cyst of pearl from which the clever pearl- 

 button maker alone liberated him." 



FISH PARASITES. 



We have, however, evidence of the occurrence of fishes of two species 

 as parasites in the true pearl oyster, or mother of pearl shell Mcleagrina, 

 not by the presence of the living fish, or even by dead specimens of 

 "• fish in the tiesh," if we may use so convenient a paradox, but by their 

 entombed remains in the form of nacreous noduhe or tubercles on the 

 shells or valves of the said mollusk. 



At a subsequent meeting of the Zoological Society (June 1, 1880), 

 Br. Giinther exhibited a specimen of a small fish of the genus Fierasfer 

 embedded in a i)earl oyster, and said : 



" The specimen which is represented in the accompanying wood cut 

 oF the natural size has been in my possession for many years. It is an 

 old shell of Margarita margaritifera* in which there is imbedded, be- 

 hind the impression of the attract or muscle, a perfect individual of a 

 tish belonging to the genus Fieraxfer. The fish is covered by a thin layer 

 of pearl substance, through which not only the general outlines of the 

 body but even the eye and the mouth can be seen. The parasitic habits 



eleagrina manjaritifcra L. 



