TT^ G. Van Name— Bermuda Ascidians. 385 



ASCIDIiE SIMPLICES. 



Fixed (rarely unattached and never free swimming) ascidians 

 which do not reproduce by budding or form colonies. 



The branchial sac is enormously developed, occupying the greater 

 portion of the body and is provided with a very large number of 

 stigmata. 



The viscera lie alongside the branchial sac, though they may pro- 

 ject behind it to a very slight extent. 



This group is usually considered a sub-order. 



Family HALOCYNTHIID-ffi. (CyntMid^ Lac. Diitli., 1877.) 



Body usuall}^ attached, sometimes stalked. 



Test membranous, coriaceous, or sometimes cartilaginous, some- 

 times incrusted with sand or other substances. Branchial and atrial 

 ajiertures usually four-lobed. 



Branchial sac longitudinally folded, with internal longitudinal 

 bars, which do not bear papilla^. 



Tentacles simple or compound. 



Intestine on left side. 



Reproductive organs attached to the inner surface of the mantle, 

 on one or both sides of the body. 



The name of the principal genus of this family was changed by 

 Verrill to Halocynthia, as the name Cynthia was preoccupied, hav- 

 ing been used for a genus of insects.* This change has not been 

 generally adopted, but appears to be required. The family name 

 requires a corresponding change. 



Polycarpa Heller, 1877. 



Body sessile or more or less distinctly pedunculated. 



Branchial sac with about four folds on each side. Tentacles sim- 

 jDle. Dorsal lamina a plain membrane. 



Reproductive organs consist of numerous small hermaphrodite 

 gonads distributed on the inner surface of the mantle, oji both sides 

 of the body. 



* Bulletin No. 15, U. S. Nat. Museum, p. 147, 1879. 

 Trans. Conn. Acad., Vol. XI. 25 February, 1902. 



