59 



ON SOME TASMANIAN TBOCHIDjE. 



By the Eev. J. E. Tenison-Woods, F.a.S., F.L.S., Corr. 

 Mem. Eoy. Soc. Tas., KS.W., Yict., and N. Z. Inste. 



[Bead 12th August, 1879.] 



In tlie Proceedings for 1877 this Society did me the honor 

 to publish in its pages a Census of the Marine Shells of the 

 Tasmanian coasts. In that list I discussed some of the 

 claims of certain species, but a great many questions con- 

 nected with the classification I was obliged to leave untouched. 

 I now propose to deal with the names of some of the 

 Trocliidce, and the validity of certain genera as regards those 

 Tasmanian species which are included in them. It will be 

 observed that in many cases I have remarked in the Census 

 that I did not consider certain genera as very reliable. I 

 do not know any family to which this is so applicable as to 

 the TrochidcB, and for the present I shall confine my remarks 

 to them. 



The family of Trochidce, as defined by Messrs. H. and A. 

 Adams, and whose divisions I shall follow, is meant to 

 include animals with an elongate tongue, median teeth 

 broad, laterals five, denticulated ; uncini very numerous, 

 slender with hooked points ; head proboscidiform ; tentacles 

 subulate, somewhat ciHated ; eyes on free peduncles on their 

 outer base, two more or less developed head-lobes between 

 the tentacles, gill single, long, linear. Sides of the foot with 

 a large neck-lappet near the eye peduncle, continuous with a 

 conspicuous side membrane bearing on its free margin, from 

 three to five tapering filaments. Operculigenous lobe often 

 ornamented with cirrhi. Operculum horny, spiral, with a 

 solid convex calcareous coat, which is rarely wanting. Shell 

 pyramidal, turbinate or em-shaped. Aperture pearly within. 



I subjoin the remarks of Messrs. Adams, which have a 

 special interest and value to all who observe the habits of 

 the animal. They say that the Trochoid scutibranches 

 embrace an extensive series of herbivorous littoral mollusca 

 characterised by the fringe lobes and tentacular cirrhi of the 

 head and sides, their pedunculated eyes, and by the pearly 

 nature of their shells, which exhibit a brilliant color when 

 the periostraca and outer coat are removed. They are 

 invariably marine, feeding among the seaweeds which 

 abound along the shore, and are distributed universally over 



