510 PHILOSOPHY OF ZOOLOGY. 



A. Simple. 



This division includes the genus Ascidia of Linn.eus. 

 The individuals are independent of each other, and al- 

 though they frequently adhere together in clusters, they 

 are destitute of a common covering, or organical connec- 

 tion. 



I. Apertures furnished with Jour rays. 



The animals of this group have the external tunic cori- 

 aceous, dry, opaque, rough, folded, and frequently covered 

 with extraneous bodies, or inclosing such. The branchial 

 orifice has four rays, the anal one the same, or divided 

 transversely. The branchiae are divided longitudinally in- 

 to persistent regular deep folds. 



a. Body pedunculated. 



The peduncle, in this division, may be said to have its 

 rise in the summit of the body, which it serves to suspend. 

 The abdomen is lateral. The meshes of the branchiae are 

 destitute of papilae. 



57. BoLTENiA. The tentacular filaments of the bran- 

 chial circle are compound. There is no liver, and the ova- 

 rium is compound. Only one species is known. B.Jusi- 



forme. Savigny, Mem. tab. i. f, 1. and tab. v. f. 5. It is 

 the Vorticella Bolteni of Lin. and the Ascidia clavata of 

 Shaw. 



b. Body sessile. 



M. Savigny describes this group as a genus, which he 

 terms Cynthia, and which he divides into four sub-genera. 



(A). Tentacular filaments of the branchial orifice com- 

 pound. The folds of the branchiae more than eight in 

 number. The liver distinct, and surrounding the stomach. 

 Ovarium divided with one division at least on each side the 

 body. The intestine destitute of a rib. 



58. Cynthia. Meshes of the branchiae unchanged by 

 the folds. C. Momus. Sav. Tab. i. f. 2. 



