308 Transactions. 



mens are distinctly P. setosus, north of this— at Peel Forest and Tinwald — 

 are found crayfish which it is difficult to place definitely in either species. 

 They have some of the characters of P. setosus and some of P. zealandicus. 

 They have been assigned to the species of which they have the most cha- 

 racters. The Peel Forest specimens are, therefore, named P. setosus, and 

 the Tinwald specimens P. zealandicus. South of Winchester the crayfish 

 found are all distinctly P. zealandicus. which extends right to the south of 

 the Island and to Stewart Island, and has been traced in the south-west 

 as far as Clifden. Here, also, there is no definite record of their occurring 

 far up the rivers, although a gentleman writing from Gore, in Central Otago, 

 states that they used to be common in the district, and a correspondent 

 from Lawrence reports that they are found there. 



In the historical portion of this paper mention was made of the occur- 

 rence recorded by J. Wood-Mason (1875) of " two species of crayfish from 

 the rivers Avon and Waimakariri respectively.'" Through the kindness 

 of Mr. S. Kemp, of the Indian Museum, Calcutta, the specimens which 

 formed the subject of Wood-Mason's paper were obtained for examination. 

 They were entered in the Indian Museum Register as follows :— 



" 900. Astacoides setosus, Hutton. R. Waimakariri. N.Z., a few 



miles within influence of tide. W. Guyse Brittan." 

 1 901 . Astacoides tridentatus, Wood-Mason. Types. R. Avon, N.Z. 

 Several miles above tidal influence. W. Guyse Brittan." 



Of these, No. 901 belong to Paranephrops setosus Hutton, of which 

 Astacoides tridentatus Wood-Mason is a synonym, and no doubt reallv came 

 from the River Avon. But No. 900 reallv belong to P. zealandicus White, 

 and probably came not from the River Waimakariri, but from the 

 Bluff, the localitv label having been interchanged with other specimens, 

 "No. 890/7," which are labelled as coming "from "The Bluff, S. Is. 

 N. Zealand, A. V. Hugel " ; these, however, are undoubtedly specimens 

 of P. setosus Hutton, and doubtless came from the Waimakariri. 



Bionomics. 



(A.) Mode of Life. 



It has been seen that crayfish are to be found in most parts of New 

 Zealand, but their number and size vary in the different districts, seeminglv 

 in accordance with the type of stream or pool in which they are found. 

 Soft, muddy river-beds seem to be their favourite homes, while they are 

 often found in holes in a sunken log or burrowing among the roots of trees 

 growing on the river-banks. An example of their restriction to this type 

 of locality is seen in their occurrence in the Waimakariri River. This 

 stream divides into two branches about twenty miles above its mouth ; of 

 these, the south branch is the typical rapid shingle-bed river, while the 

 north branch flows comparatively slowly between soft banks. Crayfish 

 have been obtained from the north branch, but I have never heard of 



ir having been found in the south branch. 



Two other localities where they are said to occur in great numbers, and 

 to grow to a large size, are the plains of Southland and the holes and pools 

 in the basins lying among the hills of South Canterbury. They are also 

 plentiful in the streams draining the low-lying somewhat swampy land 

 around Christchurch. In parts of Southland the water-races are said to be 

 " simply swarming with crayfish," which sometimes do an immense amount 

 of damage by burrowing into the banks. 



