66 BRITISH TUNICATA. 



Eugyra is characterized by having only one genital 

 mass, by the deficiency of branchial folds, and by the 

 peculiar structure of the branchial tissue, the spiral 

 arrangement of the secondary vessels of which is much 

 more complete than in any other form ; and in no 

 other genus with which we are acquainted are the 

 spirals composed of a double coil. Nevertheless the 

 Ci/uthia Dione of Savigny has a branchial sac of a 

 structure apparently similar to this, and were it not 

 for its four-cleft aperture fringed with small filaments, 

 might have belonged to the same genus. The right- 

 hand ovary in that species is placed outside the intestinal 

 flexure. 



Gorella on the one hand, and Molijnla and Eufjyra on 

 the other, form two links in the chain of affinities 

 uniting Ascidia with Cynthia. ; while each at the same 

 time possesses characters peculiar to itself. 



The test of Eugyra is thin and membranous and is 

 in every respect like that of Molf/ula; it is very 

 globular and the respiratory tubes are small and 

 approximate. 



The mantle is extremely delicate and transparent, 

 and is provided with numerous, remote, radiating, 

 muscular fibres, extending from the base of the tubes 

 and all terminating in the same circular line at a short 

 distance below ; above, they are produced into the 

 tubes, and are throughout crossed by fine, distant, 

 circular fibres. A few detached, transverse fibres 

 range down the ventral surface. 



The branchial sac extends the entire length of the 

 pallial chamber, and reaches almost from side to side. 

 It is furnished on each side with seven wide, longi- 

 tudinal, ribbon-like bands, which are attached by one 

 edge to the primary or transverse vessels at the points 

 where they cross them. These bands, how like soever 

 in general appearance to the branchial folds in Molc/ida 

 and Styela, are not to be confounded with them. They 

 are the hoinologues of the longitudinal bars so constantly 

 present in the simple Tunicata ; and they give to the 



