168 ZOOPHYTES. 



(5.) Many specimens are of very irregular shape, some temporarily, 

 others permanently ; and the aspect of some depends so much on their con- 

 dition, as readily to mislead the spectator. 



The leaves of marine vegetables are invested by specimens appearing 

 merely as superficial irregular patches. Thus some such patches, not exceed- 

 ing an inch in diameter, consisted of a number of grey systems rising above 

 the leaf, with the ascidiae marked on the side by a bright red speck. — 

 Plate XL. fig. 4, superficial patch. System enlarged, fig. 5. 



A specimen was entirely covered by oscula, wherein no determinate 

 arrangement of systems could be discovered on June 11. — Plate XLI. 

 fig. 3. It Avas then of a brownish shade, and semi-transparent in the 

 thinner parts. The dimensions are distinctly represented by the figure. 

 Its thickness varied irregularly from seven lines to fourteen. This speci- 

 men had been established originally on one of the Alga?, becoming free in 

 its progress, and now resembling the aspect of a dried fig, but not wither- 

 ed; It was literally a dense, firm, gelatinous cake. 



No definite formations could be discovered on the side exposed when 

 first inspected. But in a few days its appearance had so changed, from 

 the expansion concomitant on absorption, and acquiring a purplish colour, 

 that the systems became very evident. 



The ascidise were generally disposed in long lines or in irregular clusters. 

 They seemed individually of a flask shape, the body ovoidal, with a cylin- 

 drical neck, and an orifice, apparently as four hollow circular arcs. No 

 obvious central cavity was environed, nor was the lower orifice of the 



ascidias visible. 



Two parts of the specimen, however, exhibited a peculiar form, per- 

 haps indicating its real structure. — Plate XLI. fig. 4, a, b, representing 

 the opposite side of fig. 3. At these points a number of ascidise sur- 

 rounded a large central cavity with an elevated waving margin, shewing 

 much flexibility. The contrast between these two component parts of 

 what must be certainly judged the system was remarkable. — Plate XL. 

 fig. 8, a, central cavity, b, ascidise. 



The aspect was here so singular, as at first prompted me to suppose 

 the large central orifice environed by the flasks, some parasite animal im- 



