44 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the fifth body muscles are turned forward and the ventral ends of 

 the first body muscles turned backward, until, in our specimen, 

 they almost meet opposite body muscle III. In Streiff's specimens 

 these ventral prolongations met and united into a continuous band. 

 The arrangement of the oral retractors in our specimens recalls the 

 aggregated Oyclosalpa afinis. Streiff found a different condition, 

 the ventral oral retractor in his specimens being split posteriorly 

 into an upper and a lower branch, both extending back to and in- 

 serted upon the first body muscle. The upper branch was in contact 

 with the lower edge of the dorsal retractor. The lack of continuity 

 of the third and fourth sphincters of the upper lip with any of the 

 other muscles is again comparable to the condition in C. affinis. 

 The atrial muscles show a very well-developed retractor continuous 

 dorsally with four of the atrial sphincters and ventrally in contact 

 with but not continued into five of the atrial sphincters. The two 

 papillae, one on each side of theatral opening, recall the solitary 

 Cijclosalpa ajjinis. 



The gut is very similar to that of the solitary Cyclosalpa pinnata, 

 there being two caeca. The tip of the intestine is curled further back 

 than in other species. At its anterior end the stolon, in our speci- 

 mens, curls up on the left side and terminates in a thin thread. 



The neuro-glandular complex shows no noteworthy difference from 

 the corresponding organs of the solitary forms of the other Cyclosalpas. 



CYCLOSALPA VIRGULA, aggregated form. 



Plate 11, fig. 28; plates 12 and 13. 



This is the most asymmetrical member of the Salpa family, 1 yet 

 point by point it shows fundamental resemblance to the other species 

 of Cyclosalpa. All of our nine individuals show the same asymmetry, 

 there being no distinction between dextral and laeval individuals. 

 In general shape the zooid somewhat resembles C. baJceri, but has an 

 undivided post-abdomen more like C. jloridana. The test is like that 

 of C. bakeri. There is no stalk of attachment (peduncle), the zooids 

 being sessile upon the stolon, which is shown as a large tube on the 

 ventral side of the animals we figure. 



Four body muscles can be recognized, as in all other aggregated 

 Cyclosalpas except C. Jloridana (in which the second is either wanting 

 or is fused with muscle I), but in C. virgula the arrangement of these 

 muscles is much modified, chiefly by partial fusion with one another, 

 these fusions being very different on the two sides. The intermediate 



1 The aggregated zooids of Brooksia rostrata are nearly as asymmetrical, so also are those of Apsteivia 

 asymmetrica. 



