Art. XXI.—Notes on Amaurobioides maritima, Cambridge.*
[Read before the Otago Institute, 8th November, 1887.]
This very interesting and handsome spider was discovered by the late Dr. Smith on rocks at Allday Bay, North Otago, and sent by Captain Hutton to the Rev. O. P. Cambridge, by whom it was figured and described in 1883. A mature and two immature examples were sent to him, labelled “Marine Spiders,” but nothing was added to indicate in what sense they were marine. I have since found this spider at Shag Point, about twenty miles south of Allday Bay. It builds its nest in the clefts and crannies of rocks, some of which are at full tide exposed to the swell and battery of the South Pacific, and none are beyond reach of the spray from the breakers. Some of the nests are then completely under water. Though varying slightly with the shape of the clefts in which they are built, they are generally tubular in form, and consist of web which is of a leathery consistence and apparently impervious to water. The tubes are from one to two inches in length. At low tide the mouth is invariably open, and immediately in front of it there is often spun a short loose funnel-shaped snare. After the recession of the tide, and whilst the rocks were yet wet, I have sometimes found the mouth of the nest sealed up. Perhaps they are all so sealed when under water, but this is a point I have been unable to determine. It seems all one to the spider whether in or out of water; for I have frequently filled a nest with water, and its occupant has never shown any signs of discomfort. Taken from its nest and placed at the edge of a pool, it will, after a good deal of teasing, run down the side to the bottom, and there remain till all danger seems to have disappeared. Seen thus, its body covered with silvery globules of air, it is a very handsome object. Unlike Robsonia marina, Cambridge, it does not seek its prey in the water, but lies in wait at the mouth of its nest for the insects that abound on the rocks, in the clefts of which it builds. It is a plucky little animal, and fights very stoutly to retain possession of its nest.
The male is smaller and of a more slender build than the female, but exactly resembles her in colourations and markings. His cephalothorax is more rounded at the sides and more constricted at the caput, and his legs are longer than hers. Those of the fore pair are distinctly (1 ½mm.) longer than those of the hind pair. The male may be readily recognised from Cambridge's excellent figure of the female.
New Zealand is, I believe, the only country in which spiders have been found inhabiting the sea.
[Footnote] * Proc. Zool. Soc., June, 1883, PI. xxxvi., fig. 3.