. pt. 2.] A TAXONOMIC STUDY OF THE SALPIDAE METCALF. 29 



There are no lajiguet-like protuberances opposite the ventral por- 

 tions of the intermediate muscles, as in Cyclosalpa pinnata, but there 

 are a pair of minute papillae, one on each side of the atrial opening. 

 These were of larger size in the individual figured by Ritter and John- 

 son. Their internal structure suggests comparison with the tubular 

 outgrowths of the mantle and test, which in Thalia, and especially in 

 Tran stedtia, are so much more developed. 



The ganglion and its ventrolateral outgrowths, the neural glands 

 and the eye resemble those of the solitary Cyclosalpa pinnata too 

 closely to need description. 



CYCLOSALPA AFFINIS, aggregated form.' 



Plate 3, fig. 10; plate 4, figs. 11 and 12. 



The aggregated form of Cyclosalpa affinis again presents evidence 

 of close relationship between this species and C. pinnata, though there 

 are some differences from the aggregated individuals of the latter 

 species. The test is very much thicker, especially dorsally and ven- 

 trally, but it is as soft. The body muscles are the same in number, 

 but in C. affinis the bands are more nearly parallel, i. e., body muscles 

 I and II do not touch dorsally or ventrally and III and IV do not so 

 closely approach dorsally. The body muscles in both species are 

 continuous across the mid line dorsally, while ventrally all are inter- 

 rupted except the posterior branch of the last. 



The condition in the peduncle muscles, in the intermediate muscles, 

 and in the last body muscles at their ventral ends need comparison 

 with their condition in the aggregated Cyclosalpa pinnata. In C. 

 affinis the ventral portions of the intermediate muscles approach and 

 touch on the mid-ventral line of the body. They continue ventrally 

 as full width bands closely appressed to each other for a short dis- 

 tance into the peduncle, their tips again separating slightly. It is 

 therefore evident that the anterior peduncle muscle in this species is 

 double, as in C. pinnata. 



In Cyclosalpa pinnata the first and second body muscle on each side 

 unite to form one of the pair of posterior peduncle muscles. In C. 

 affinis the posterior peduncle muscles are distinct from all the body 

 muscles. They do not closely approach either the first or second 

 body muscle. They do bend back and approach near to the third 

 body muscles on each side, somewhat above the mid line, but they 

 do not unite. The slight protuberance from the front of the pedun- 

 cle in figure 10 is probably without significance. It is not found in 

 many individuals. 



The ventral ends of the posterior branches of the fourth body mus- 

 cle (IV, a) unite and continue into the visceral evagination (post- 



1 United States National Museum collections. Cat. No. C449. 



