96 THE PROCEEDINGS OF THE LINNEAN SOCIETY 



As no dimensions are given, this is somewhat unsatisfactory, 

 but it applies much more to T. australis, than to any other. Mr. 

 Angas's short diagnosis on the contrary, applies to T. tceniata. 

 The specimens seen by me in the Museums of Melbourne, 

 Sydney, Hobart Town, and Dr. Cox's extensive private collec- 

 tions, were all var. tceniata. Some obtained by Mr. Brazier, from 

 Mr. Angas, were all young shells of T. constricta. 



The conclusions I derive from these considerations, are — 



1st. That we have commonly at most only three species of 

 Trochococlilea on our shores, viz., T. constricta, T. tceniata, and 

 T. australis. 



2nd. That T. constricta and T. tceniata can only doubtfully be 

 separated from one another. 



3rd. That both these species are subject to great varieties of 

 colour and form. T. constricta being the larger in Tasmania, and 

 probably the smaller in South Australia, or else these being vari- 

 ties of only one species, the smaller and larger varieties inter- 

 change their characters. 



4th. That T. striolata, T. concamerata, and T. porcata, are all 

 synonyms ; the first two for T. australis, the last for T. constricta. 

 Lam. 



All these shells are distinguished by the lining of the upper 

 whorls being non-nacreous, and of a beautiful malachite green. I 

 noticed also in some places on the Tasmanian coast, a certain 

 form intermediate between T. c , and T. t, in which the whorls 

 were very obtuse, the shell large and smooth, and painted in 

 zig-zag lines of vivid bluish green, and white. The upper 

 whorls and apex were much corroded, and of silvery nacre. 

 This variety always flourished on modern basaltic rocks in 

 Recherche Bay, and elsewhere, where no other mollusca seemed 

 common, and often where the water was brackish. It was a 

 large shell, and the keels are almost completely obsolete. 



It is a remarkable fact, that the larger shells of these species 

 are found in S. Tasmania, and they become smaller, more 

 decidedly ornamented, and highly coloured as they approach the 

 tropics. 



