NoTT. — On N.Z. Composite Ascidians. 305 



Akt. XXV. — On the Composite Ascidians of the Nortli Sliore 



Beef. 



By J. T. NoTT, M.A. 



[Read before the Wellington Philosophical Society, 2Mh Fchruary, 1892.] 



Plates XXIV.-XXX. 



Part I. — Introductory. 



Across the harbour of Auckland to the north-east Hes the 

 North Shore suburb, and still further beyond in the same 

 direction the volcanic island of Eangitoto rises, se2:)arated 

 from the mainland by the channel of that name. Skirting the 

 western shore of this channel for some few miles the cluster of 

 rocks known as the North Shore Eeef is reached : a favourite 

 collecting- ground for the zoologist, and one which has already 

 provided much interesting material for the student of our New 

 Zealand fauna. These rocks, only a few acres in extent at 

 the most, are quite submerged at ordinary high tides, and, 

 except at low spring-tides, are separated from the beach by a 

 shallow stream of no very great width. The numerous pools 

 left at low tides, protected as they are from the violence of the 

 waves by the outlying barriers, afford a congenial home to 

 many of the lesser denizens of the deep. Two fields of re- 

 search, at present almost, if not quite, unexjDlored, here offer 

 themselves : first, the sponges, of which great numbers may 

 be distinguished ; and, secondly, the Composite x^scidians, 

 with some of which this paper deals. 



I have, for the sake of convenience, dividedmy subject into 

 three parts. The first is purely introductory, and deals with 

 the subject in its more experimental aspect, discussing the 

 methods employed, the means available, and matters of a 

 similar nature. The second will deal with the anatomy and 

 histology of the various species, as far as I have been able to 

 elucidate them. The third will then summarise the facts 

 noted previously, and deduce therefrom any conclusions of 

 importance such as may be, in my oj)inion, warrantable. 



The first visit to the collecting-ground was made early in the 

 month of July, in company with Professor Thomas, when, owing 

 to the rapidly-rising tide, nothing was done beyond gaining a 

 practicafknowledge of the locality. A second visit, a fortnight 

 later, resulted in my securing five distinct species.* Of these 



* Lcptoclinum nivciLvi, L. clenswn, L. tuheratum, Cystodytes pcrspi- 

 cims, and PoIysy7icraton paradoxiLin, 

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