MISCELLANEOUS. 67 



An instance of this appeared from thirty or forty single hydrae in 

 their cells, resembling so many spines, about two lines high, to the naked 

 eye, seated on the skin of an animal which I was inclined to associate with 

 the Ascidise. 



I have had various specimens of this animal, chiefly from the confines 

 of the German Ocean, but none so perfect, so recent or vigorous, as to de- 

 termine its certain position. However, it seems to be a cognate of the 

 Polycluuum aurantium, represented by M. Milne Edwards, in his Treatise 

 Sur les Ascidies composes, the only portion of that author's observations 

 on the Ascidise which I have seen. — Plate xxxvi. fig. 1. 



Under the microscope, this zoophyte was found consisting of an ovate 

 cell, sustained by a cylindrical, smooth, transparent pedicle, about half its 

 length, and a fifth part of its diameter. Within the cell, the hydra at 

 rest remains folded on itself, like similar ascidian tenants, with the orifice 

 above closed over it. But the fold relaxes as the hydra rises to protrude 

 its pencil of tentacula through the orifice, which are soon expanded as 

 twenty long, ciliated, percussive organs, endowed with the wonted faculties 

 of the race. The neck, when protruded, is so transparent, as to expose 

 deglutition of the buoyant particles tossed about among the tentacula. 



The cell is apparently somewhat of membranaceous texture ; it be- 

 comes distorted, and it stands awry on its pedicle. The orifice rises with 

 the protruding animal, and contracts on its retreat. From the dispropor- 

 tion between the cell and the pedicle, this zoophyte waves with the slightest 

 motion. 



The form of the cell bears some resemblance to a grain of wheat, and 

 the whole colony tended to faint yellowish colour. 



As the substance of the Ascidia sustaining the zoophytes seemed in 

 a short time verging to decay, I separated a thin slice of the skin, which, 

 pierced with a needle, was suspended by a thread in a convenient position 

 among sea-water. 



The skin now remained entire ; the hydrse upon it were also preserved, 

 but none of them survived above eleven or twelve days from the time 

 when they were taken, which was in the end of June. They died in the 

 cell, the body being attached to the lower part. 



