BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S., ETC. Ill 



York, a distance of very near 3,000 miles. It is evidently a 

 tropical species, and grows largest and is in the finest condition 

 within the tropics. I do not think that an impartial person could 

 avoid recognizing it as one species, even though a comparison 

 were instituted between specimens from the two extremes, that 

 is from South Cape in Tasmania and Cape York in Australia. It 

 is not very common at Port Douglas, of large size — (1| "ich in 

 length) — and of bright colours. The brown spots in the spathula 

 are paler and more distant, and all the colouring is more distinct. 

 The radula or lingual ribbon is exactly similar in the sj)ecimens 

 wherever they are obtained. We have therefore in this an 

 example of a species which thrives through a very wide area, but 

 is evidently better adapted for a warm climate. The case is thus 

 the reverse of the Littorina pyramidata. 



But we have another example on this coast which is different 

 again. Acmcea septiformis, Quoy and Graimard, is as all naturalists 

 are aware very common on all the coasts of Southern and South- 

 eastern Australia and Tasmania. It is not so well-known that it 

 is found at intervals aU along the coast into the tropics. At Port 

 Douglas it is very common in places, but generally far up on the 

 rocks and not very easy to discover. It is neither smaller nor 

 larger than the specimens in my possession from the coldest part 

 of Tasmania, and it does not seem to have varied in its colouring. 

 That is to say it is as variable on the North Coast as on the South, 

 but much within the same limits. It has always been my 

 impression that no distinction could be made between this species 

 and A. testudinaria, of Muller, which is so common in Great 

 Britain, and since our species can be traced in the hottest as well 

 as the coldest seas in Australia, without alteration, and on 

 thousands of miles of coast we may well beHeve that it is of world- 

 wide distribution. 



I call attention here to these facts, because they show how no 

 general rule can be adopted for the way in which mollusca are 

 affected by climate. We have thus — 1. Acm(Ba marmorata, which 



