COMPOUND ASCIDIA. 159 



while the diffusive matter remains transparent, is obscured by the succes- 

 sive multiplication, thickening, and intervention of parts. 



The whole asciaise of this specimen were yellowish and finely speckled 

 white. In their latest stage they were quite yellow. None survived the 

 fourth of July. 



It may be said they have yellow blood. 



§ 3. A specimen of larger dimensions than any of the preceding, afford- 

 ed many valuable results in confirmation of the real nature of the Bo- 

 tryllus. 



This subject, which occurred at the distance of twelve or fifteen miles 

 or less from the site of the three shells, and, I believe, in shallower water, 

 resembled a mass, of solid, consistent, semi-transparent, gelatinous, olive- 

 green matter, tending to brownish-yellow. Its form was extremely irregu- 

 lar, scarcely admitting comparison with any given figure; but it might 

 have been bounded by the sides of a parallelopiped, 42 lines in length, 18 

 in breadth, and 12 deep. The whole of warty appearance, was covered by 

 prominences very low, almost even with the surface. 



The specimen had been founded originally on some of the more delicate 

 of the marine Alga; overspreading them in its growth, from which it 

 had hung in its native site, as they now passed through the centre. — 

 Plate XXXVII. fig. 12. 



From the mere external aspect, it was impossible to conjecture what 

 this substance might be, more than a lump of inanimate matter. Nothing 

 could be farther than the whole from indicating any thing like vitality. 



But the imprudence of indulging precipitate opinions Avould have soon 

 betrayed the naturalist, for after I had supended the shapeless mass, in a 

 suitable position amidst the water of a capacious glass vessel, symptoms of 

 animation were speedily evinced, by relaxation of the superficial warts 

 into so many cellular prominences, apparently with a smooth even edge, 

 when viewed in profile, fig. 13. As the product became familiarised with 

 its new abode in a short time, numerous orifices opening in these promi- 

 nences expanded as from united hollow circular arcs, forming an internal 

 margin, like those of the preceding Botryllus. 



