ASCIDIA. 145 



jar of sea-water, to avoid the peril of pressure, the Ascidise survived three 

 weeks. Nevertheless, they began to mould on the lapse of that period, 

 having probably sustained some injury before reaching me. 



The full-grown Ascidia is generally a very rude and coarse produc- 

 tion in external appearance. 



Plate XXXIV. Fig. 6. Ascidia rustica, colony. 

 Plate XXXV. Ascidia rustica, young brood. 

 Plate XXXVI. Fig. 7. Ascidia rustica, young \ 



§ 4. Ascidia scabra. — Plate XXXVI. Fig. 2. — The aspect of this 

 species is very different from that of the preceding ; it resembles a fine 

 smooth plum, 18 lines long by 12 broad, with a very thick transparent in- 

 tegument, enclosing a red kernel. 



The general figure of the species is a rude, somewhat flattened ovoid. 

 Commonly the integument is about two lines, or the sixth part of an inch 

 in thickness, like very solid diaphanous ice or jelly ; but a little thinner 

 above at the orifices, of smooth and even surface, unless for some inequali- 

 ties on the upper part, and where affixed by the base. The coat of the 

 kernel, which contains the internal organs, is finely reticulated, as dis- 

 tinctly seen when interposed between the naked eye and a penetrating 

 light. The intestinal tube curves from the bottom upwards to the lower 

 orifice, just within the red portion, wherein the principal organization is 

 lodged.— Plate XXXVI. fig. 2. 



Smaller Ascidise frequently occur, which, without farther preserva- 

 tion, cannot be identified with any of the larger, familiar to us, they are 

 so different in form and colour. Such is one not a quarter of an inch 

 long, always white, found adhering to the corallines. Another, having 

 still to undergo much alteration, I was indueed to conjecture the young of 

 the Ascidia scabra. The external integument was thick and clear : the 

 internal surface of the second tunic yellow and reticulated. — Fig. 3. The 

 same, enlarged, fig. 4. 



A small Ascidia, deposited in a vessel during autumn, began to ad- 

 here in two days, promising to become useful and convenient for observa- 

 tion. This subject was pale grey, speckled red, and of such colour as to 



VOL. II. t 



