Page:Transactions NZ Institute Volume 15.djvu/119
Art. III.—Notes on, and a new Species of Subterranean Crustacea.
By Charles Chilton, M.A.
[Read before the Philosophical Institute of Canterbury, 5th October, 1882.]
Plate IV.
Corrections and Additions to previous Paper.[1]
In my previous paper I have stated that the well from which the Crustacea were obtained was "not more than twenty-five feet deep." I have since found that this is considerably too much, it is really only sixteen or seventeen feet deep; since then, however, the well has been filled in, so that it is now practically the same as though the pipe had been simply driven into the ground as in an artesian well.
The Crustacea still continue to come up, though not so frequently as before, and they now vary more, sometimes coming up pretty abundantly while at other times they are very scarce; and while previously Calliope subterranea (female) used to be much more abundant than any of the other species, it now, though still more abundant than the others, does not preponderate over them nearly so much as before. Next come Crangonyx compactus and Cruregens fontanus which occur in about equal numbers, while Gammarus fragilis is now the rarest of all.
From another pump about two or three chains from the first, I have obtained a few specimens of Calliope subterranea (female), and from a third pump about a mile and a half distant I got a single specimen of Gammarus fragilis, and I have heard of similar animals being seen from another pump about a mile distant from the first one, but I have not seen specimens from this well. These facts seem to show that the Subterranean Crustacea are fairly well distributed in the district.
All these wells are sunk in a bed of gravel which lies immediately under the surface soil. Through this gravel water continually percolates, and can always be found at the depth of a few feet from the surface, the depth varying according to the situation, the dryness of the season, the state of the neighbouring River Eyre, etc. I do not think that there is anywhere any large connected quantity of water, but I believe that the Crustacea live in the water which percolates through the interstices between the stones in the bed of gravel.
With regard to the origin of these Crustacea one can as yet only conjecture. Their nearest allies appear to be marine in their habitat. Cruregens fontanus would, but for the absence of the last pair of thoracic legs, come under the genus Paranthura, the species of which, as well as of the allied genus Anthura, are all marine. Besides Cruregens fontanus, I have obtained
- ↑ "On some Subterranean Crustacea," "Trans. N.Z. Inst.," vol. xiv., p. 174.