ANATOMY AND LIFE HISTORY OF MOLLUSCA. 113 



in nothing interesting ; besides occupying an immense space to no 

 purpose. I shall confine my observations, therefore, to those 

 lines of inquiry to which my own attention has been specially 

 directed, and which have proved most fruitful in interesting 

 discoveries. 



For the convenience of reference, I shall make three divisions 

 in the Molluscan Sub-kingdom, namely: — 1. Marine Mollusca. 

 2. Fresh-water Mollusca. 3. Land Mollusca. This division, 

 which is of course not zoological, is more convenient for me, for 

 reasons which will appear as we proceed. I shall deal in this 

 essay with the Marine Mollusca almost exclusively. 



The Molluscan character of any portion of the Australian coast 

 differs according to its climate and situation. In no country 

 perhaps in the World, are there more long stretches of low sandy 

 coast, without rocks or indeed anything but sand-dunes. This is 

 especially the case on the coast of N. Australia, where the shore 

 is so low, and the sea so shallow, that except in a few places no 

 vessel of any size can keep within sight of it, and it is not often 

 visible, except by the smoke of bush fires, at a distance of four or 

 five miles. In such regions, very little is to be seen of littoral 

 Mollusca. A few bivalve shells are scattered along the sand-dunes, 

 the species varying according to the locality. On the north coast 

 these are : — Mactra, Tapes, Cytherea, Asaphis, &c. On the south 

 coast such regions are especially rich in Donax, Venus aphrodina y 

 Lam., V. lamellata Lam., (which probably extends as far as 

 China), Mytilus, &c. 



In places where the shore is rocky, there is a complete change 

 in the fauna. Within the tidal-marks, but generally in the 

 highest part of them, we find a Patella outside the tropics, and a 

 Nerita within tropical regions, though Patellidse are not wanting 

 also, with Acmaia, Planaxis, Littorina, Monodonta, Chiton, &c. 

 On the south coast we have Patella, Aemcea, and Siphonaria, with 

 two or three species of Littorina, Trochoeochlea, and Risella. 

 These species are generally out of the water. Within the tropics, 

 amongst the mangrove swamps, there are the usual brackish- water 

 species of Nerita, Cerithidea, Telescopium, Melampus, Auricula^ 

 Pythia, Cyclas, Littorina scabra, L., and rarely Austriella sordida, 

 a genus of the author's.* 



The above named littoral species offered such special facilities 

 for study, that from the very first they attracted my attention 

 particularly. There are, as all those moderately acquainted with 

 the subject are aware, under the guise of shells presenting no 



*See Proc. Royal Society of Victoria, Vol. xvii., 1881, pp. 80-83, pi. 1, 

 figs. 10-11, " On Some New Marine Mollusca." The new genus Austriella 

 is distinguished as including thick non-nacreous shells, with a smooth, 

 arcuate, hinge margin, without teeth, with a persistent periostraca. 



H— June 6, 1888. 



