Page:Transactions NZ Institute Volume 15.djvu/120

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another Isopod (described in the latter part of the paper) whose nearest allies are marine. Calliope subterranea is inconclusive, for we have in New Zealand one marine and one fresh-water species; it is, however, not at all near to C. fluviatilis the fresh-water species, and certainly has not arisen out of that species.

Gammarus fragilis, again, does not prove anything, for though in New Zealand we have only one species, a marine one, in Europe some species are marine and some fresh-water. The genus Crangonyx contains only two species besides C. compactus, mihi, one C. subterraneus from a well in England, the other C. ermanni from warm springs in Kamschatka; its nearest allied form, however, is a marine genus, Gammarella.

On the whole, both the Isopoda and the Amphipoda are so distinctly marine and their fresh-water representatives in New Zealand so few, in fact only two, Calliope fluviatilis and Idotea lacustris, that it is difficult to believe that the subterranean fauna, which, so far as at present known, contains five species, could have arisen from any other than the marine fauna.

Cruregens fontanus.—Since writing my previous paper I have obtained a great number of specimens of this species—between 40 and 50—and they all agree in having the last thoracic segment small and without appendages, so that there can no longer be any doubt that the form I have described is the adult form.

In living specimens the heart can be distinctly seen through the transparent integument. It is elongated and extends from the middle of the fifth abdominal segment anteriorly, reaching nearly to the middle of the sixth thoracic segment. The anterior end of the heart is narrower than the posterior part, and the posterior end is rounded. There appear to be three openings through which blood flows into the heart; one is on the left side in the second abdominal segment; the other two are on the right side, one in the seventh (last) thoracic segment, and the other in the third abdominal segment. These openings appear to be provided with valves of some kind. Blood passes out through the anterior end of the heart, in the median line of the body, and flows forwards to supply the various parts of the body.

In my previous paper I have stated that the only blind Isopoda inhabiting wells or caves that I could find mention of were two species of a genus, Cæcidotea, found in the Mammoth Cave of Kentucky and in the Wyandotte Cave; since then I have found two others mentioned, but I have not been able to get descriptions of them; they are Titanethes albus, Schiödte, which inhabits caves of Carniola[1] and Typhloniscus steinii.[2][3]

  1. ↑ See "Nature," 18th April, 1872, p. 484.
  2. ↑ See "Trans. Linn. Soc.," 2nd ser., vol. I., pt. i., p. 24 (footnote).
  3. ↑ Others are mentioned in the Zoological Records for 1879 and 1880.
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