16 Transactions. — Zoology, 



antennal scale is rather short, and it is broadest in the- 

 middle." 



This species, as restricted by Faxon, appeal's to be common 

 throughout Otago and Southland, and has been recorded also 

 from Stewart Island. 



In connection with this species, Faxon gives the result of 

 some observations I had communicated to him on the varia- 

 tions in size, &c., that occur in correspondence with the quan- 

 tity of water in which the crayfishes live. In small streams 

 around Dunedin and Port Chalmers, where the flow of water 

 is small, the specimens are all small, sexually mature speci- 

 mens not exceeding 84 mm. in length, and in them the cara- 

 pace is well-nigh destitute of spines and tubercles. In places 

 where these streams have been dammed up to form reservoirs, 

 such as the Dunedin reservoirs, or the small one connected 

 with the Glendermid Tannery at Sawyer's Bay, the crayfish 

 attain a much larger size, even up to 158 mm. in length, and 

 in them the sides of the carapace are heavily tuberculated, 

 the tubercles having the form of prominent, smooth, rounded 

 papillae. 



If sexually mature specimens from the small streams and 

 from the reservoirs are examined without knowledge of the 

 conditions under which they occurred, they would almost 

 certainly be considered as different species by the vast majority 

 of svstematists. 



3. Paranephrops setosus, Hutton. 



Paranephrops setosus, Hutton, Ann. Mag. Nat. Hist., 4th ser., 



xii., p. 402 (1873) ; Chilton, Trans. N.Z. Inst., xv., p. 150, 



pis. xix-xxi. (1882). Paranephrops neo-zelanicus, Chilton 



(in part), Trans. N.Z. Inst., xxi., pp. 246, 249, pi. x., 



figs, la, 2a (1888). Paranephrops setosus, Faxon, Proc. 



United States Nat. Mus., xx., p. 681 (1898). 



Faxon regards this species as distinguished from P. zea- 



landicus by the following characters : "The cephalothorax is 



more oval than in P. zealandicus, owing to the bulging of the 



sides of the carapace ; the sides of the carapace are thickly 



strewn with acute, forward-turned spines, which take the 



place of the rounded tubercles in P. zealandicus. The rostrum 



and antennal scale are longer, the lateral rostral teeth longer 



and more spiniform ; the rostrum is furnished with an evident 



median keel, most prominent on the distal half of the rostrum 



(in P. zealandicus there is a gastric keel, but no keel on the 



rostrum)." 



The species as thus restricted has been recorded only from 

 the Avon and Heathcote, at Christchurch, and from streams 

 at Eangiora. The largest specimen examined was 145 mm. 

 in length. 



