43 



which, as far as my knowledge serves me, it is absent — while, on 

 the other hand, the Aslacus alone is met with in the tribu- 

 taries of Macquarie Harbour. The range of these two then 

 the Astacus and the Blackfish, is nearly the same, neither of 

 them being found within the rivers flowing to the east or south 

 coasts of the island. Yet there is nothing in the habits or 

 the necessities of the Astacus which would explain its pre- 

 sence in, or absence from, respective rivers ; although pre- 

 ferring deep still pools and reaches, in which it may shelter 

 beneath submerged and partially decaying timber, it is also 

 commonly found in the shallower and swift running portions, 

 and there are few of the streams adverted to from which it is 

 absent, which do not, as far as may be judged from appearance, 

 offer in some portions of their course, the kind of harbour, 

 and if one may use the expression, cruising ground to which 

 the Astacus is familiar, while the myrtle shrouded waters of 

 the higher portions of the Huon identically resemble the 

 upper portion of the rivers to the northward, in which both 

 the black fish and the Astacus abound. 



As to its ordinary food much misapprehension has hitherto, 

 in my opinion prevailed. 



The eagerness with which it fastens on any animal bait, 

 the threatening aspect of its general appearance, and the 

 enormous crushing power of the claws with which it is armed, 

 have induced the belief that it mainly exists upon fish which 

 it has captured, or the large species of Unio found in some of 

 the northern rivers, and the absence of the latter from the 

 southern ones, were considered a sufficient explanation of its 

 being wanting also. This, however, appears to me to be 

 erroneous, and from my observation I have concluded that the 

 capture of fish or other animal prey by the Astacus is a rarity, 

 and that as in many instances the Unio is entirely absent from 

 the rivers which it inhabits this as a source of its food must be 

 entirely disregarded. Indeed, to my great surprise, I found 

 upon dissecting numerous examples of the Astacus, that the 

 contents of the stomach consisted almost entirely of crushed 

 and torn fragments of semi-decayed wood, and I have arrived 

 at the conclusion that the main source of its subsistence are 

 the slowly decaying stems and snags with which the timber 

 bordered rivers are always encumbered. 



Now, as the adaptation of the Astacus to certain localities 

 in consequence of the presence of especial means of subsis- 

 tence is untenable, the decaying timber abounding equally in 

 the southern with the northern rivers, it becomes imperative 

 to seek another solution, and we are thus led in considering 

 the reputed identity of the Blackfish of this colony with that 

 abounding in Victoria, the close similarity of the species of 



