Paraleptamphopus subterraneus Stebbing, 1906, p. 294; Chilton, 1909B, p. 54 (with synonyms).

This species is very widely distributed in New Zealand. It was first obtained in wells at Eyreton not far from the River Waimakariri; it has since been found in wells in Christchurch, Lincoln, Leeston, Ashburton, and Winchester. Later on I collected it in surface streams issuing from river-terraces near the River Porter, a tributary of the Waimakariri, and it is common in streams and ditches near Drummond and Otautau, Southland, where it is found associated with P. caeruleus, as already mentioned. Messrs. Lucas and Hodgkin took it in Lake Wakatipu, and in 1908 I found it in a small stream at Duck Cove, Doubtful Sound, in places where the stream was almost covered and shut out from the light by the overhanging rocks and trees. In the North Island it was taken by Lucas and Hodgkin in Lake Taupo at a depth of 700 ft., and in 1911 Mr. W. F. Howlett sent me numerous specimens from a well at Eketahuna. All these specimens are pale and colourless, with eyes imperfect or completely absent, and, though they show considerable differences in the exact shape of the telson, the third uropoda, and the gnathopoda, there is no difficulty in considering them as all belonging to the same species.

In 1914, however, Mr. T. Hall sent me specimens which he had collected at “Clippings,” on the range of mountains known as the Remarkables, near Lake Wakatipu, and from Mount Dick, in the same neighbourhood, the animals in the latter case being found at a height of 3,000 ft. above sea-level. These specimens were rather stouter in body than the forms obtained from wells, the third uropods were shorter and similar to those of P. caeruleus, and they showed the dark-blue colour characteristic of the latter species, though it was not quite so intense, and some of the specimens were much lighter than others; the telson, too, proved to differ distinctly from that of the type. At first I was inclined to consider them as a new species, but a careful comparison of the forms of P. subterraneus from the different localities mentioned has shown that numerous transitional forms exist as regards the individual characters, and that if a new name were given to the forms from “Clippings” and Mount Dick several new names would have to be established for the others. Though largely intermediate between the two species, the “Clippings” and Mount Dick specimens approach more nearly to P. subterraneus in the telson, and I therefore look upon them as a variety of that species.

The structure of P. subterraneus was somewhat fully dealt with by me in 1894 so far as the underground forms were concerned. It will only be necessary to mention now a few of the points in which differences occur in specimens from other localities. In all specimens the gnathopoda are of similar shape, the first stouter than the second; in the Eyreton specimens the palm of the first is minutely crenulate, but it is even in these from surface waters in Southland. The appearance of the third uropod varies when seen from the side or from above. Fig. 4 shows those of a specimen from Eketahuna, fig. urp³ being one of the pair seen from above, fig. urp³* the other from the side; the branches are not much longer than the base, on the latter there is usually a small tuft of setules at the upper distal angle, and two or three separately placed on each upper margin. In specimens from Southland streams the tuft at the distal