3. Note on a Species of Hydra new to New Zealand,
During a recent visit to Shag Valley Station, near Palmerston, my host, Mr. A.D. Bell, mentioned that he had frequently found a species of Hydra in a pool in his grounds.
On examining the tips of the roots of trees and other plants which push their way into the water round the sides of the pool I found specimens of this little animal, which differ in several respects from the small pale-brown species which is to be met with in the pond in Woodhaugh Garden, and in some streams round Dunedin.
The present species is of a rich reddish-brown, almost mahogany colour, though some are rather of a sienna tint—the colour, of course, being in the endoderm.
In size they greatly exceed the common species, one individual measuring about ¾ in. (15 mm. in alcohol), excluding the tentacles. The tentacles are few in number, 5–7 in the individuals examined.
The specimens were budding freely, one having as many as three buds of different ages.
Till they have been examined microscopically, and till I have searched the recent literature, it is impossible to say whether this species is new to science, though it is certainly new to New Zealand.
The only records of the occurrence of Hydra in the Dominion are by the late Dr. Coughtrey. In the Transactions for 1875* he writes (p. 299), “I have seen two Hydrœ in New Zealand—one nearly like H. viridis, of Britain, and the other I have not been able to identify with the British members of the Gymnochroa.”
In the version of the same paper published in the “Annals and Magazine of Natural History” for 1876† he writes (p. 24), “I discovered a pretty fresh-water Hydra in some pond-water, attached to one of the leaves of the plant Natella ucra” [sic, probably Nitella Hookeri]. This Hydrá in general form is like H. viridis, Linn., in colour pale brown, and has 7 tentacles, which are peculiar in this respect, that they are distinctly annulated, and each ring is fringed.”
It is clear, I think, that this refers to the first of the species mentioned in his former article; and probably it is the one that I have found round Dunedin. The “annulation” of the tentacles is due to the arrangement of the batteries of nematocysts, and is not peculiar to the species. What he means by the “fringing” I do not know, and will not hazard a guess.
[Footnote] * Coughtrey: “Critical Notes on New Zealand Hydroida.” Trans. N.Z. Inst., 1875, vol. viii, p. 298.
[Footnote] † Coughtrey: “Critical Notes on New Zealand Hydroida, Suborder Thecaphora.” Ann. Mag. Nat. Hist. (4), xvii, p. 22.
The little brown Hydra I have found is of quite a different colour and size from the Shag Valley specimens.
It is not improbable that this little brown species is the common H. fusca of Britain; but, unfortunately, it is catalogued as H. viridis by Farquhar,* who appears to have misread Coughtrey; and this name is repeated in the Index Faunæ N.Z., but so far as I am aware the green Hydra has not been recorded in this country.
[Footnote] * Farquhar: “List of New Zealand Hydroida.” Trans. N.Z. Inst. 1895, xxviii, p. 468.