422 ON THE OCCURRENCE OF PLECOTREMA, ETC., IN PORT JACKSON 



NOTES ON THE OCCURRENCE OF A SPECIES OF 



PLECOTREMA AND OF OTHER SPECIES OF 



MOLLUSCA IN PORT JACKSON. 



By J. C. Cox, M.D., F.L.S., C.M.Z.S. 



An interesting addition to the known fauna of Port Jackson 

 lately occurred to me, in Plecotrema octanfracta, Jonas. This 

 species appears to possess some unusual facilities for wandering, 

 which it shares with other Auriculidce, and with Truncatella, for 

 it has been observed in the Sandwich, Paumotu, Gambier, Tonga, 

 Samoa, Fiji, and New Caledonia Islands, though not hitherto 

 recorded from Australia, nor from any extra-tropical station. It 

 is not noticed from Port Jackson in the lists of Angas or of 

 Whitelegge, but Pfeiffer has described as from Port Jackson a 

 Plecotrema hicolor (Mon. Auric, p. 103 : B. M. Cat. Auriculidce, 

 p. 78) doubtless the species under discussion. A species, probably 

 allied to this, P. ciliata, Tate, is quoted in Adcock's " Hand-List 

 of the Aquatic Mollusca inhabiting South Australia." 



The earliest description appears to be that by Jonas in the 

 Zeit. Malak. 1845, p. 160. Garrett redescribed the species in 

 P.Z.S. 1887, pp. 295-6, and figured it under the name oi P. conso- 

 hrhia (Proc. Phil. Acad. Nat. Sci. 1873, pi. iii, fig. 69). The 

 members of this genus do not seem to have been discriminated in 

 a satisfactory manner. Messrs. H. and A. Adams published in 

 1853 (P.Z.S. pp. 120-3) the definition and a monograph of the 

 genus, based chiefly upon the material contained in the Cuming 

 Collection. To one not possessing access to the types in the 

 British Museum this paper is of slight value. No figures are 

 attached, many species are unlocalised, the descriptions are brief 

 and without measurements, and finally, Jonas's Pedipes octanfracta 

 is entirely omitted. 



