BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S., ETC. 123 



in the neighbourhood of Port Douglas, and there is the Great 

 Barrier Reef at about 16 miles distance from the shore. All 

 these literally teem with life, so that a life time would not be 

 enough to enable one to know and see all. I shall confine my 

 remarks first of all to those matters to which I have been calling 

 attention in the first part of this paper. 



Littoral shells are not common on the reefs — that is to say, such 

 shells as Patella, Littorina, Nerita, Planaxis, &c. The reason of 

 this is probable that these molluscs live for the most part out of 

 the water, and there are only very few parts of the reefs that are 

 not covered for more than 1 2 of the 24 hours ; those portions that 

 are uncovered are not, as a rule, favorable stations for the species 

 I mention. There are not many solidified rocks, but only loose 

 banks of a coarse sand, composed of coral and shell debris. This 

 sand becomes cemented in the course of time into a hard dark- 

 brown, calcareous rock. If there is much coral in it : the structure 

 is very coarse and hard. Large masses of coral, with equally 

 ponderous clams, volutes. Cassis, TrocJms, «S:c., making up a 

 peculiar and highly ornamental stone, the finer portions become 

 stratified into thin flags with a gentle dip towards the sea. On 

 such rocks I noticed SipJionaria denticulata, or a variety of it. 

 Probably some other specific name has been given to it, but where 

 the differences are so very slight, and the features upon which 

 specific distinctions are made to rest are so liable to vary for 

 almost every individual, it would be hazardous to attempt to 

 determine which variety it is. The whole genus needs a thorough 

 revision, and when it receives that, the Australian species will 

 no doubt be found confined to four or five. 



Two of the most common univalve shells upon the reefs are 

 Pterocera Iambi's, Linn, and Sfromhas luhuamcs, Linn. They must 

 have a ver^^ wide range, as they are described as occurring at the 

 Ived Sea, and through the whole of the Indian Ocean. Both 

 species are amongst the oldest known to men of science. They 



