»'. ' on ihe Natural Group of Tunicata.. 349 



be accidental, as it appears in no way connected witli the internal 

 organization, although on compressing the body the fluid con- 

 tents of the inside issued from this aperture. The second false 

 aperture does not appear more connected with the internal or- 

 ganization than the other, but, is externally of rather a complex 

 appearance. It consists of a circular cavity, of which one half 

 is surrounded by a thin raised margin. On one side of the inte- 

 rior of this cavity we see a mamillated eminence supporting two 

 more minute mamillae. What the use of this apparent organiza- 

 tion is I cannot imagine, as it is situated on the space between 

 the rings of the tentacula and the branchiae, and seems therefore 

 accidental. The branchial aperture is surrounded by a raised 

 margin, within which we indistinctly see the four rays. On open- 

 ing the animal, however, and viewing the branchial orifice from 

 the inside, we find these four rays which compose it very distinct. 

 The tentacula are very simple filaments, unequal in size. The 

 folds of the branchial pouch are very distinct, and in the inter- 

 val between them run two longitudinal nervures connected by 

 transverse threads, which are again connected by short longitu- 

 dinal filaments, thus forming a simple respiratory net- work. 



The organs of digestion have great aflSnity in external struc- 

 ture and position to those of Cynthia pantex of Savigny, except 

 that the stomach and intestine are horizontal, and the anus sim- 

 ply margined. 



The extraordinary characteristic, however, of the animal is 

 the many-branched unique ovary which coats the tunic on the 

 left side behind the branchiae, and which, when first seen through 

 the semipellucid external envelope, gave me an idea of its internal 

 structure being very different from what it afterwards proved to be 

 on accurate dissection. The truth is, that different as this species is 

 in external appearance from all other Ascidia, internally it agrees 

 with the Pandocice in almost every essential respect but the ovary. 



4 B 2 It 



