BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S., ETC. 113 



will make it break clean away. The radula of this species is short 

 in comparison with P. tramoserica, being seldom over three inches 

 in length. 



A mollusc, which is here in far greater abundance than any of 

 the PafellidcB whose form it resembles, is a species of Siphonaria. 

 It would be very diflficult to assign a name to it without consider- 

 able study into the claims of species, but I certainly think it is 

 only one of the many varieties which from time to time have been 

 distinguished by the names of S. diemene7isis, Baconi, funiculata, 

 and many other s-^nonyms. It is a ribbed shell, with white ribs 

 and brown insterstices, but I cannot see any or even much 

 difference between the varieties that have been named. It is just 

 as common within the tropics as all along the east and south 

 coasts of Australia and Tasmania. The animal is the same in 

 every respect and the radula also. I think the tj'pical specimens 

 have a little advantage in point of size, but that is the only 

 difference I can detect. It is more numerous than any of the 

 Patellidcd, and this holds good of every part of the coast which I 

 visited, within the Barrier Eeef , but I have not often found it on 

 coral reefs or anywhere except rocks, fringing the shore above 

 the tidal marks. I consider it as especially characterizing the 

 littoral fauna of Australia. I am not aware whether or not it 

 has been remarked that the genus Siphonania is more peculiar to 

 the Southern hemisphere than the Northern. 



In estimating the peculiarities of the littoral fauna at Island 

 Point, Port Douglas, it must be borne in mind that the rock 

 formation may have something to do with it. That formation is 

 a dark phonolite stone which does not easily decompose, neither 

 does it give rise apparently to much ferruginous earth or clay. 

 Yet I attribute something to its influence. It abounds with 

 Planaxis sulcata, as I have already remarked, the Patellidcd are 

 also abundant, so are oysters and several species of Nerita to be 

 mentioned presently. On the coral reefs close at hand there are 

 equal numbers of oysters. Patellidcd are not common, though not 



