314 MALACOZOA. APODA. HETEROBRANCHIATA. 



and moved for half an hour, after being deprived of its outer 

 sac, contracted the upper half of the inner sac into a longi- 

 tudinally ribbed and transversely rugose firm cylinder, turned 

 it slowly in various directions, and moved the siphons sepa- 

 rately. This inner sac has about twelve, longitudinal muscular 

 bands of a whitish colour, crossed by smaller muscular bands. 

 From the upper orifice, a tube passes into the branchial cavity, 

 which extends nearly to the bottom of the sac, and is lined by 

 a delicate longitudinally striate and transversely striulato- 

 granulated membrane, the respiratory organ ; the mouth is a 

 simple aperture about a fifth from the bottom of the sac ; the 

 oesophagus is short, narrower than the intestine ; the stomach 

 ovato-oblong, three-twelfths of an inch in width ; the sigmoi- 

 dally curved intestine a twelfth and a- half in width, ascending, 

 and terminating in the lower, six-lobed orifice. The whole 

 length of the intestinal canal is four inches. Attached to the 

 stomach is a thin reddish soft glandular mass, apparently 

 analagous to the liver. Between the stomach and the first 

 curve of the intestine is an oblong white ovary, which sends 

 oft a slender tube of the same colour, running along the in- 

 testine to the aperture. The length of the individual described 

 is, when extended, three inches, its breadth at the base one 

 and a-fourth ; length when contracted one and a-half. 



Very abundant in deep water, off Aberdeen, adhering to 

 dead shells, stones, agglutinated sand, and other substances. 

 Corallines, small shells, and other bodies, often adhere to it ; 

 and Modiola discors is very frequently found imbedded in its 

 outer coat. 



Ascidia intestinalis. Linn. SystNat. 10S7. Ascidiaintestinalis. 

 Lamk. Syst. iii. 126; Ed. 2. iii. 533. Phallusia intestinalis. 

 Savigny, Mem. 107, 115, 169. PI. ll.f. l.Ciona intestinalis. Flem. 

 Brit. Anini. 468. Phallusia intestinalis. Hiss. Eur. Merid.lv. 275. 



A few other species have been met with; but the 

 difficulty of determining them induces me for the present 

 to leave them undescribed. 



