you 2, pr. 2.] A TAXONOMIC STUDY OF THE SALPIDAE METCALP. 75 



The atrial muscles, well shown by Streiff (fig. 52), conform to the 

 condition seen in the solitary Kitterias and the solitary Cyclosalpa 

 virgula, except that in the latter species the distal sphincters are not 

 connected with the retractor (pi. 11, fig. 26) and in Rittcria retracta 

 Ritter shows the atrial retractor external to the atrial sphincters 

 (fig. 25, p. 54). Streiff describes, and our specimens show, a folding and 

 interruption of the marginal sphincters dorsal to the atrial retractor. 



Both lips of the solitary Apsteinia punctata bear the numerous 

 delicate cylindrical branches of a gland ( ?) whose histological struc- 

 ture suggests that it may possibly be a phosphorescent organ (fig. 49). 

 It3 form, however, is very different from any known luminous organ 

 in other species. Glands of similar appearance, though less devel- 

 oped, are on the lips of the aggregated zooids. Behind the gut, and 

 on each side of it, are similar branching glands in the solitary form. 



The eye is in the condition usual in the solitary Salpidae. 



APSTEINIA PUNCTATA, aggregated form. 



This zooid (fig. 53) is strongly asymmetrical, though not so much so 

 as is the aggregated Brooksia rostrata (fig. 24, p. 52) or the aggregated 



— -Mb. 



a. a 



&.O. 



B 



KlO. 83.— AP8TEINIA PUNCTATA, AGGREGATED ZOOID FROM THE LEFT SIDE OF THE STOLON: A, VENTRAL 



view; B, dorsal view. Form Streiff (.1908) wna modifications. 



Cyclosalpa virgula (pis. 11, 12, and 13). Its muscles are sufficiently 

 indicated by the figures. In this species, as in Brooksia rostrata, there 

 are dextral and laeval individuals. 



The body muscles are five in number, the fifth being divided into the 

 usual two branches seen in the aggregated zooids of other species. 

 On one side only of the body, a delicate branch arises from body 

 muscle V b and runs to the region of the gut (fig. 53 A). This 

 reminds one of the delicate branch in the aggregated zooids of 



