34 BRITISH TUNICATA. 



the top in a slightly curved line to the atrium, where 

 it terminates in an anal orifice with a reflected and 

 lobed margin. 



The ovary is a branched tubular organ, for the most 

 part confined to the right side of the intestinal loop, 

 through which a few of the branches pass and appear 

 at the left-hand side ; a few of the terminal ramifica- 

 tions also overlap the dorsal border of the stomach 

 and reach the other side of it. The male casca, which 

 are elongated, are for the greater part confined to the 

 left-hand side of the looped portion of the intestine. 



This delicate species is not likely to be confounded 

 with either of its two congeners, from both of which 

 it differs in many particulars, and notably by the 

 general form and by the character of the branchial 

 spirals, which in C. ovata are not by any means so 

 many times coiled as they are in both the other species, 

 and the coils themselves are much stouter. In C. 

 parallelogramma and ('. larvaeformis the spirals are 

 from 5 to 7 times coiled, while in C. ovata, they are 

 coiled only twice or thrice. 



Family 2. MOLGULULE. 



Animal generally free or only slightly attached. 

 Test thin and membranous, often covered with sand or 

 fragments of shells ; usually not at all or but very 

 slightly attached to the mantle, except at the two 

 apertures. Branchial aperture 6-lobed, at rial aperture 

 4-lobed ; ocelli inconspicuous or none. Tentacular 

 filament* branched. Branchial sac generally with 

 longitudinal folds, the meshes more or less perfectly 

 convoluted, without papillae. 



