OCR Text |
Show 1903.] OLIGOCHJETA FROM NEW ZEALAND. 207 and immature specimens of Tubifex sp. and of Limnodrilus, amongst which some appear to be L. vejdovskyanus. Lake Waikare, North Island. Greatest depth 9 feet. Only one haul was taken, which yielded numerous specimens of Limnodrilus vejdovskyanus and one individual of Taupodrilus simplex. It will thus be seen that the lakes in the North and South Island respectively differ considerably in their Oligochaates, so far as research has yet gone. The two species of Phreodrilus are very distinct, one confined to the north, and the other evidently common in the southern lakes. Of Taupodrilus, the northern and southern representatives may be distinct, though I have included them in the same species, as the southern material was not in sufficiently good condition to permit m e fully to investigate the details of the reproductive organ. Unfortunately the southern representatives of Limnodrilus are immature, but they appear to differ in the form of their cha?ta^ from each of the northern species, L. vejdovskyanus from Waikare and L. lucasi from Taupo. PHREODRILUS LACUSTRIS, sp. n.* A very narrow worm in which the ventral chcetce are in couples of two kinds : each couple consists of {a) a simple hook-like bristle and {b) a hook with a very minute tooth in the back. These chaetse measure 0-06 m m . in length. The ventral chsetaB are absent on segments xii., xiii., though on the latter segment they are replaced by special copulatory chasta?. Dorsal chsetse solitary, capilliform, beginning on segment iii. The clitellum covers the hinder part of segment xii. and the whole of xiii. The male pores are in line with the ventral chaeta? at the hinder margin of segment xii. The oviducal pores are in the same line, at the boundary of segments xii./xiii. The spermathecal pores are in line with the ventral chsetse at the anterior margin of segment xiii. Copulatory chcetce, a pair of couples; each pair in a special ovoid glandular follicle just behind the spermathecal pore. The preclitellar nephridium appears to extend through segments vii. to x. N o sperm-sacs ; but loose developing spermatozoa in segments viii. to xii. Spermiducal gland of large size, filling segment xii., slightly convoluted, receiving the sperm-duct at its short, narrow neck, where it enters a large protrusible penis, enclosed in a muscular * A detailed account of this species has been sent to the Editor of the Quart, Journ. Micros. Sci. |