Art. XIX.—Notes on a New Zealand Land Nemertine.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 27, 1894, Page 191

Art. XIX.—Notes on a New Zealand Land Nemertine. By Arthur Dendy, D. Sc., Professor of Biology in the Canterbury College, University of New Zealand. [Read before the Philosophical Institute of Canterbury, 5th September, 1894.] The nemertines form, as is well known, a typically marine group of animals, being abundant and widely distributed in shallow seas. Very few species seem to have deserted their marine habitat in favour of a terrestrial one, so that land nemertines are exceedingly rare. Up to the present time, indeed, only five species have been described—viz., Tetrastemma agricola, discovered on the “Challenger” Expedition, and described by Dr. Von Willemoes-Suhm; Tetrastemma rodericanum, discovered at the Island of Rodriguez by the Transit of Venus Expedition, and described by Mr. Gulliver; Geonemertes palaensis, found by Professor Semper in the Pelew Islands; Geonemertes chalicophora, found by Professor Von Graff in gardens in Germany, and probably introduced there by human agency; and lastly, Geonemertes australiensis, discovered by myself in Victoria, and described with anatomical details and illustrations in the “Proceedings of the Royal Society of Victoria” for 1891. Like the land planarians, to which they are in some measure related, the land nemertines belong to the cryptozoic fauna, being found under fallen timber, stones, &c., and probably only venturing from their hiding-places at night or in very wet weather in search of prey. They are small, slimy worms, closely resembling land planarians at first sight, but readily distinguished by the sudden emission of a long, white proboscis from the anterior extremity when the animal is irritated.

Having been much interested in these animals in Victoria, I have naturally been on the look-out for them since my arrival in New Zealand, and I have recently found two specimens of an indigenous land nemertine, not, unfortunately, in their native habitat, but put away in spirits amongst collections of land planarians. The first specimen I found in a small jar of land planarians collected in various unspecified localities in New Zealand, and most kindly given to me by Mr. Suter. The presence of only four eyes in this specimen, and the characteristic arrangement of alternate dark and light bands on the dorsal surface, clearly indicated that it was specifically distinct from Geonemertes australiensis, although the sections (cut by the usual paraffin method) showed a close agreement in general anatomical features. Unfortunately the proboscis was missing, it having been doubtless everted and broken off, as so frequently happens when nemertines are placed in alcohol. Thinking that there might possibly be specimens of land nemertines similarly put away amongst other worms in the Canterbury Museum, I appealed to Captain Hutton, who immediately looked through the collection of worms in spirit for me, and gave me a bottle labelled, “Land Planarians, Toitoi, Southland; Miss J. G. Rich.” For this and much other kind assistance of a similar nature I desire to express my great indebtedness to Captain Hutton. On examining this small collection of land planarians from Toitoi I found another specimen of Geonemertes, with the pattern on the dorsal surface much fresher-looking and more distinct, but otherwise identical with Mr. Suter's specimen. Moreover, in this case, the proboscis, although it had been everted and cast off, was found in the bottle. Thanks to the discovery of this second specimen, I am now in a position to give a sufficient description of this New Zealand land nemertine to serve for purposes of specific determination, and I propose to name it Geonemertes novæ-zealandiæ, n. sp. The larger specimen (in spirit) was a little less than 1in. in length and about ⅛ in. in diameter. It was nearly oval in transverse section, but somewhat flattened ventrally, terminating bluntly in front and behind, and with an aperture at each extremity. The surface was transversely wrinkled, more strongly dorsally than ventrally. Two dark spots, one at either side of the blunt anterior extremity, seemed to indicate the position of the eyes, but these, being deeply imbedded, were not clearly visible until sections were cut. The colour was pale, dull yellow, with alternate light and dark longitudinal bands faintly visible on the dorsal surface,

and arranged as follows: There is a median broad light band; on each side of this comes a broad dark band of about the same width; then comes a light band of about half the width; and this is followed on the outside by a very narrow dark band, situate at about the junction of the dorsal and ventral surfaces. Thus it appears that there are four dark bands or stripes—viz., a pair of inner broad ones and a pair of outer narrow ones. The second and somewhat smaller specimen, collected by Miss Rich, agreed exactly with the first in external characters, but, being apparently fresher, the dark bands on the dorsal surface still retained a rich chocolate-brown colour, the other parts of the body being of a pale-yellow. In sections stained with borax-carmine and cut by the paraffin method I could only detect four eyes, situated deeply beneath the epidermis of the rounded anterior extremity. These are arranged in two pairs, those of the one pair being considerably larger than those of the other, and placed a little more anteriorly and ventrally. The smaller ones were difficult to make out satisfactorily, because the pigment appears to have been dissolved by the action of the alcohol; the large ones were very distinct, with the usual pigmented cup. With regard to its eyes, therefore, Geonemertes novæ-zealandiæ conforms to the more usual condition met with in land nemertines, and differs markedly from the Australian species. Other anatomical characters, so far as I have been able to make out from the limited material at my disposal, agree very closely with those of G. australiensis. The mouth opens into the rhynchodæum (in other words, there is only a single aperture for mouth and proboscis-sheath). Lateral organs, including cephalic pits, are well developed, and appear to closely resemble those of G. australiensis. The nervous system, muscular system, and alimentary canal do not seem to depart from the usual type. The structure of the proboscis, with its marvellous armature, appears also to agree closely with that of previously-described species. The calcareous stylets have the usual form, and I detected four reserve-sacs in the usual position. Probably, however, this number is not constant. The sexes are probably distinct, for in the specimen of which I cut sections I found abundant ova, but no spermatozoa. A very strongly developed “cephalic gland” occurs in the same position and with the same histological structure as in G. australiensis, to the account of which species I would refer the reader for further particulars as to the habits and anatomy of these remarkable worms.

Certain minor histological differences will probably be found to exist between the two species, as, for example, the occurrence of numerous peculiar, round or ovoid, thick-walled, nucleated bodies just within the longitudinal muscle-layer of the body wall in Geonemertes novæ-zealandiæ; but these are details into which I cannot enter at present.