184 BYNE : MARINE iMOLLUSCA OF TEIGN MOUTH. 



having the mark of a fah'ly fibred byssus, apparently de- 

 rived from the mussels, should prove convincing. From 



the preceding facts, it seems that O. rissoides is a 



parasitic species. 

 O. pallida Mont. Dredged alive in mud, trawled alive on 



rough attachments and on F. operciilaris. 

 O. acuta Jeff. Dredged alive and dead in mud. 

 O. acuta van umbilicata Aid. Three trawled alive on 



separate occasions, and dredged dead in muddy ground — 



this is probably a new locality. 

 O. unidentata Mont. Dredged alive and dead. 

 O. turrita Han. Live examples from under stones at low 



water ; dredged dead. 

 O. plicata Mont. Live specimens under stones, but only 



once. 

 O. insculpta Mont. Trawled alive ; dredged alive and dead; 



one example, with animal in it, amongst drift. 

 O. diaphana Jeff. Live specimens in a bucketful of Zoster a 



marina trawled by a steam yacht ; dredged alive and dead. 

 O. warren! Thomps. Dredged alive and dead. 

 O. dolioliformis Jeff. Has been obtained on two occasions 



alive and in quantity from the lowest spring tide water 



marks of the littoral zone in this bay. Dead examples in 



drift. 

 O. decussata Mont. Dead in drift. 

 O. indistincta Mont. Dredged alive and dead in mud, and 



dead specimens in drift, all being of dwarf growth. 

 O. indistincta var. brevior Jeff From a bucketful of 



Zostera trawled by a yacht. 

 O. Interstincta Mont. One specimen only dredged alive. 

 O. spiralis Mont. Dredged alive and dead in mud ; live 



examples from under stones at low tides ; dead specimens 



in drift. 

 O. rufa Phil. Two dead examples in trawled refuse. 



J.C., \ii., Apr. 189;^. 



