Ill 



On the Larva of an Ascidian found at the Land's End. 



By A. D. Michael. 



(Read November 28th, 1884.) 

 PLATE V. 



Gentlemen, — I am going to ask you to bear with me to-night, as 

 you have often done before, while I occupy a few minutes of your 

 time with some remarks which do not contain any new or original 

 matter whatever ; but when I find some object in microscopical 

 biology which I think interesting, it usually strikes me that others 

 who have similar tastes may be of the same opinion ; and, there- 

 fore, if I succeed in securing what seem to me to be fairly good 

 preparations of it, and if similar slides are not often before the 

 Club, I like to show them to you. I think that merely placing 

 them on the stage of a microscope on the table is, after all, a poor 

 mode of exhibition, as the points of interest are most likely to be 

 missed, unless a few words be said calling attention to them. 



Last autumn, whilst searching for marine life in my favourite 

 hunting-ground at the Land's End, I came across several groups of 

 compound- Ascidians which appeared to me worthy of notice, from 

 the fact that there were eggs and larvae in all stages of development, 

 as well as adults. I mounted some of these for microscopical 

 examination, and three preparations are under the microscopes to- 

 night, viz. : — 



No. 1. An egg with the larva fully developed and ready to hatch. 

 Stained with hsematoxalin. 



No. 2. A mature larva stained with hsematoxalin. 



No. 3. A mature larva slightly stained with picro-carmine. 



The specimens belong to the genus Leptoclinwn, and the species 

 is, I think, either gelatinosum or maculosum. The Tunicata of this 

 genus form thin films coating stones, lammariae, &c, the individuals 

 being imbedded in a jelly-like mass as in Botryllus, but they have 

 not the beautiful stellate arrangement round a common anus, with 

 which we are all familiar in that genus, but are irregularly scattered, 



