on the Natural Group of Tunicata. 549 
be accidental, as it appears in no way connected with 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 mamillæ. 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 branchiæ, 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 affinity 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 branchiæ, and which, when first seen through 
the semipellucid external envelope, gave me an ideaof 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 dscidie, internally it agrees 
with the Pandocie in almost every essential respect but the ovary. 
j ABQ It 
