Chilton. — On Astacus fiuviatilis and Paranephrops setosus. 151 



I have seen P. setosus only. P. planifrons is a perfectly distinct species, 

 and is found abundantly in many places in the North Island of New Zea- 

 land. P. setosus is not known to occur in the North Island, but it is widely 

 distributed in the South Island, being found in the Kiver Avon, Christ- 

 church, from which the specimens for this paper were obtained, and also in 

 the rivers near Invercargill, at the south of the island. Thus P. planifrons 

 appears to be confined to the North Island, and to be represented in the 

 South Island by P. setosus. 



P. zealandicus was described as belonging to New Zealand by White in 

 1847,* but it does not appear to have been since recognized. Professor 

 Hutton, who at the time when he described P. setosus in 18731 had no 

 opportunity of consulting White's description, tells me that he thinks it 

 very probable that P. zealandicus is nothing more than a young specimen of 

 P. setosus. From the comparison of the two descriptions in Miers' Cata- 

 logue, and from the figure in the Zoology of the Voyage of the Erebus 

 and Terror, this appears very likely to be the case, and it also agrees well 

 with the small size of P. zealandicus (3 inches) as compared with that of 

 P. setosus (5f inches). 



With regard to P. zealandicus, Mr. Miers says :| " This species is cer- 

 tainly distinct from P. setosus, Hutton. In P. zealandicus, of which the 

 type specimens are in the British Museum Collections, the hands are 

 clothed externally with tufts of hair arranged in longitudinal series, and 

 are armed with spines only upon the superior margins, and the sides of the 

 carapace are smooth. In P. setosus there are spines arranged seriately 

 upou the external surface as well as the upper margin of the hand, and the 

 branchial and hepatic regions of the carapace are armed with numerous 

 inequal conical spines." The first point will certainly not serve to distin- 

 guish the two species, for there are tufts of hair on the hand of P. setosus, 

 there having been a slight mistake in Professor Hutton's description (see 

 below). With regard to the other points they are certainly subject to some 

 variation in P. setosus, and it is quite possible that the spines on the hands 

 and on the sides of the carapace may be developed only in the older speci- 

 mens, but I have not been able to examine a sufficiently large number of 

 specimens to give a decisive answer on this point. However, there are 

 certainly only the two species, P. planifrons and P. setosus, known to New 

 Zealand collectors, and this leads one to think either that P. zealandicus is 

 not a distinct species or that the locality given is wrong, and that it belongs 

 to Fiji, where a species of Paranephrops is found. § 



* Proc. Zool. Soc , p. 123. 



t Ann. & Mag. Nat. Hist., ser. 4, xii., p. 402. 



+ Ann. & Mag. Nat. Hist., ser. 4, vol. xviii., 1876, p. 412. 



§ Huxley, " The Crayfish," p. 306. 



