Art. V.—Note on the Fresh-water Crayfishes of New Zealand.

By Charles Chilton M.A., D.Sc., M.B., C.M., F.L.S., Research Fellow, University of Edinburgh.

When Captain Hutton described P. setosus he had before him, as Faxon points out, specimens from the River Avon, Christchurch, and from Invercargill—i.e., of P. setosus (sensu strictiori) and of P. zealandicus. His description, however, has evidently been drawn up from the River Avon specimens only, though the large specimen in the Otago Museum labelled Paranephrops setosus in Hutton's own handwriting, and therefore presumably a type specimen, proves to be a specimen of P. zealandicus from a different locality.

I give below brief abstracts of Faxon's descriptions of the three species, with the more important references only; the full references are given in Faxon's paper.

1. Paranephrops planifrons, White.

Paranephrops planifrons, White, Gray's Zoolog. Miscell. No. II., p. 79 (1842); Chilton, Trans. N.Z. Inst., vol. xxi., pp. 242, 249, pl. x., figs. 1–3 (1888); Faxon, Proc. United States Nat. Mus., vol. xx., p. 678 (1898).

Faxon speaks of this as a puzzling species. In specimens from Puriri Creek, a tributary of the Thames, from which White's type specimens were obtained, he says, “The rostrum tapers off into a long and sharp acumen, which overreaches the distal end of the antennular peduncle. Each side of the rostrum is armed with three teeth, which are produced into long spine-like points…. The antennal scale is long, and diminishes in width from the basal third to the tip; it exceeds the rostrum in length. The post-orbital ridge is interrupted between the two sharp spines with which it is armed. A median ridge runs along the gastric area, reaching forwards as far as the anterior pair of post-orbital spines, but not continued on the rostrum. There are two or three sharp spines on each side of the carapace, just behind the cervical groove, besides several more on the hepatic and ptery-gostomian regions. The areola is very short and broad—not much over one-third as long as the distance from the cervical groove to the tip of the rostrum. The abdominal pleuræ are bluntly angulated. The hand is long and narrow, its superior and inferior margins nearly straight, parallel, and armed with a double row of spines—those on the superior margin the longest. The inner and outer faces of the hand are convex, and sparsely armed with spines, the largest of which are disposed in a median longitudinal row on each face.”

Specimens from Karaka, Manukau Harbour, are quite similar, but those from Lake Roto-iti and more southern localities “differ constantly in having a shorter rostral acumen, shorter lateral rostral teeth, shorter and broader antennal scale; the areola, or, in other words, the posterior section of

the carapace, is much longer, being nearly one-half as long as a line drawn from the cervical groove to the anterior end of the rostrum; the hand, too, is provided with shorter fingers, and the lower half of the hand is more heavily tuberculate both on the inner and outer faces.”

Large specimens from Roto-iti and Napier have the sides of the carapace thickly set with blunt tubercles, which become spiny only on the hepatic and pterygostomian regions and along the cervical groove; but in similar large specimens from Nelson all the tubercles tend to assume the form of spines. Specimens from Wellington and Pelorus River, Marlborough, have the lateral rostral spines increased in number and reduced to short, blunt teeth, and the antennal scale short and broad, broadest at the middle, with very convex internal border, and thus vary in the direction of Paranephrops zealandicus.

As I have already shown in my previous paper, Paranephrops planifrons is widely distributed in the North Island, and also occurs in the north-west portion of the South Island, the most southerly locality from which it has been recorded being Greymouth.

2. Paranephrops zealandicus, White.

Astacus zealandicus, White, Proc. Zool. Soc. London, pt. 15, p. 123 (1847). Paranephrops neo-zelanicus, Chilton (in part), Trans. N.Z. Inst., xxi., p. 249 (1888). Paranephrops zealandicus, Faxon, Proc. United States Nat. Mus., vol. xx., p. 680 (1898).

In this species “the chela is much shorter and broader than in P. planifrons, and it is furnished with conspicuous dense tufts of silky hair, disposed in longitudinal rows. The upper margin of the hand is armed with a series of prominent spines, continued as a double row on the margin of the dactylus. The lower margin of the hand is furnished with a double row of shorter spinous teeth. The outer face of the hand is provided with a few tubercles, which seldom develope any spinous points; the inner face bears two longitudinal rows of short teeth. The rostrum is armed on each side with small, blunt teeth, usually five in number, but in some individuals three, four, or six; the inferior edge is either unarmed or else provided with one or two acute teeth; a median carina runs over the gastric area, ceasing abreast of the anterior pair of post-orbital spines, the rostrum proper being wholly destitute of a median dorsal keel. In small specimens the sides of the carapace are smooth, or at the most reveal only the slightest trace of low rounded papillæ; but in large specimens, that have attained a length of 115 mm. or more, the sides of the carapace are thickly studded with rounded tubercles. The

antennal scale is rather short, and it is broadest in the middle.”

This species, as restricted by Faxon, appears 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 variations in size, &c., that occur in correspondence with the quantity 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 specimens not exceeding 84 mm. in length, and in them the carapace is well-high 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 papillæ.

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 systematists.

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, pls. xix-xxi. (1882). Paranephrops neo-zelanicus, Chilton (in part), Trans. N.Z. Inst., xxi., pp. 246, 249, pl. x., figs, 1a, 2a. (1888). Paranephrops setosus, Faxon, Proc. United States Nat. Mus., xx., p. 681 (1898).

Faxon regards this species as distinguished from P. zealandicus 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 Rangiora. The largest specimen examined was 145 mm. in length.