274 BIOLOGICAL LABORATORY OP SYDNEY UNIVERSITY, 



Species of this genus have been long known as accustomed to 

 burrow in the shells of Molluscs — among othei'S of the oyster — as 

 well as in any sandstone, or shaley, or calcareous i-ock ; but they 

 do not seem to have been regarded generally as serious enemies of 

 the oyster. 



Oersted (1) does not mention the boring propensities of 

 Leucodore at all, but merely describes it as found on a sandy 

 bottom. Grube (2) describes it as perforating cretaceous rocks at 

 Dieppe. In his " Histoii-e Naturelle des Anneles," Quatrefages 

 does not allude to the shell-invading habits of the genus, but 

 describes it as either living in delicate tubes, or in burrows in 

 sand or calcareous rock. But Macintosh, in a paper " On the 

 boring of certain Annelids " published in the Annals and Magazine 

 of Natural History, for 1868, mentions that he had observed 

 Leucodore ciliata burrowing in the shells of various molluscs, 

 among others in those of the oyster. I have not been able, 

 however, to find any record of such extensive destruction of oysters 

 effected by this little annelid on the European coast as seems to be 

 taking place on the Hunter River (3), where no doubt some 

 local circumstances, such as muddiness of the water produced by 

 increasing traffic, tend to decrease the vital powers of the oysters 

 and thus favour the inroads of the parasites. 



The species which is found most adundantly in these oysters 

 from the Hunter River beds is, strange to say, identical with the 

 European Polydora ciliata of Johnston (4). 



I found, however one specimen o£ a second species which appears 

 to be very distinct and of which I append a description. 



(1) Annulatorum Danicorum Conspectus, Fasc. I. 



(2) Beschreibungea neuer oder wenig bekannter Annelideu. 



(3) Prof. Huxley, in a popular article on the oyster in the " English 

 Illustrated Magazine " of last year, mentions that he had received from Sir 

 Henry Tliomson specimens of oysters which were invaded by a species of 

 Leucodore, but adds that the oysters seemed little the worse. 



(4) Clapar^dt^s P. Agassizii is apparently the same as P. ciliata (Ann(ilides 

 Chetopodes du Golfe de Naples, p. 314, pi. XXIL, fig. 1.) 



