142 ZOOPHYTES. 



tural state, and the opposite extremity disengaged above, is not to be as- 

 certained. In captivity it always lays horizontally, without any effort, that 

 I have seen, to penetrate downwards, or even to shift its position. 

 This animal is very rare. 



Plate XXXIV. Fig. 1. Ascidia villosa. 



2. Orifices a, i, enlarged. 



3. Young specimen. 



§ 2. Ascidia intestinalis. — Plate XXXIV. Figs. 4, 5. — This ani- 

 mal bears some resemblance to a Florence oil-flask, with two necks of 

 nearly equal dimensions, having a larger and a smaller orifice. It extends 

 between three and four inches in length, and, where thickest towards the 

 lower extremity, it is about nine lines in diameter. The whole skin is 

 smooth, and of a fine grass-green colour, with a vivid yellow margin bor- 

 dering each orifice. The larger orifice is octagonal, the smaller hexa- 

 gonal. 



There seems to be a variety wherein the larger orifice is subdivided 

 into sixteen, instead of consisting of the usual number of eight convexities, 

 with eight equidistant orange spots on the exterior of each orifice. Seve- 

 ral specimens have been seen thus distinguished. 



This animal is of translucent, soft, and delicate appearance. — 

 Plate XXXIV. fig. 4. 



It is easily injured by pressure. 



The ordinary habitation of this species is in the double, and often the 

 single cavity of old oyster shells, wherein a group of five or six may be 

 occasionally discovered in contact, closely packed together. But by rend- 

 ing such double shells asunder the Ascidia? are generally much injured, for 

 they are in firm adhesion by a large portion of the side and to both valves, 

 instead of adhering by the base as some others. Laceration or abrasion is 

 almost always fatal. 



These creatures occupy double shells from an early age ; the orifices 

 protrude through the valves for the purpose of nutrition, though a very in- 



