Archbt. — Fresh-water Crayfish of New Zealand. 297 



In 1876 E. J. Miers published a " Catalogue of the Crustacea of New 

 Zealand," in which he recognizes the three species — P. planifrons, P. zea- 

 landicus, and P. setosus — quoting White's original description for P.plani- 

 frons (1842) and for P. zealandicus (1847), and that of Hutton for P. setosus 



(1873). 



Dr. Chilton, in his first paper on the fresh-water crayfish (1883), definitely 

 described the differences between the English crayfish (Astacus fluviatilis) 

 and a New Zealand one {Paranephrops setosus). P. planifrons he recognized 

 as a species quite distinct from the South Island form ; but he agreed with 

 Professor Hutton that P. zealandicus, which was described by White in 

 1847, and had not since then been recognized in New Zealand, was probably 

 ,: nothing more than a young specimen of P. setosus Hutton."" 



In 1885 Filhol recorded the three species, P. planifrons White, P. zea- 

 landicus (White), and P. setosus Hutton. 



In 1889 Dr. Chilton published a second paper on the subject, entitled 

 " The Distribution and Varieties of the Fresh-water Crayfish of New Zea- 

 land." The investigation was undertaken with a view to settling the 

 question raised in his first paper (1883) of the identity of the two species 

 P. setosus Hutton and P. Zealand ions (White). He remarked that the 

 characters in which they differ varied to a large extent, owing to size and 

 age, even in specimens taken from the same stream, and such a complete 

 series of transitions was found that it would, he thought, be found necessary 

 to combine the two species. The name then given to the South Island 

 species was P. neo-zelanicus. P. planifrons, too, exhibited a wide range of 

 variable characters, sometimes approaching the South Island form. An 

 important point was the distribution of P. planifrons, commonly called the 

 North Island species, but found also all over the north- western part of the 

 South Island. Dr. Chilton's conclusion was : *' It would hence appear that 

 Cook Strait has not proved so great, or, rather, so old a barrier to these 

 crayfish as the mountains in Nelson forming the northern continuation of 

 the Southern Alps." 



Walter Faxon (1898)' gave a detailed description of the three species 

 from material supplied by Dr. Chilton. He considered P. tenuicornis 

 Dana to be the same as P. planifrons White. With regard to P. zealandicus 

 (White) and P. setosus Hutton, which Dr. Chilton (1889) had combined 

 under the name P. neo-zelanicus, he considered that " the two species are 

 perfectly distinct, even young, very small specimens being easilv dis- 

 tinguishable." 



Dr. H. Lenz (1901) recorded the occurrence of "P. setosus" from 

 D'Urville Island, but as the specimens I have received from this locality 

 and from Nelson and Blenheim are all distinctly P. planifrons I have 

 concluded that his identification is incorrect. There is nothing in the 

 description given to indicate definitely to which species it belongs. 



It will be seen from the foregoing that there has been some difference 

 of opinion as to whether P. zealandicus and P. setosus are to be regarded 

 as distinct species or not. In the latter part of the following description 

 of the species this subject will be discussed. 



General Account of the Species of Paranephrops and their Dis- 

 tribution. 



The method adopted of working out the variations with a view to 

 determining the distribution of the different species or varieties was that 

 of comparative measurement for proportion. A series of measurements 



