vol. 2, pt. 2.] A TAXONOMIC STUDY OF THE SALPIDAE METCALF. 61 



a postero-lateral protuberance 1 from the body is an unconnected 

 broad muscle which probably should be included among the body 

 muscles (fig. 32). No corresponding muscle is known in other 

 Ritterias or in the Cyclosalpas. 



The atrial muscles (fig. 31) resemble those of the aggregated 

 Cyclosalpa bakeri, the distal delicate sphincters being connected 

 (doubtless on each side) with a delicate retractor, a distinct stronger 

 retractor being connected with the broad basal sphincter (fig. 33, B). 

 In the aggregated Cyclosalpa bakeri this basal retractor is present only 

 on the left side. The descriptions and figures of the aggregated 

 Ritteria amboinensis do not include the atrial muscles of the right side. 



The oral muscles (fig. 31) include a retractor and, in the upper and 

 lower lips, two sphincters each, the details of whose connections are 

 not figured or described. Ihle shows the oral retractor internal to 

 the broad intermediate muscle (his " Bogenmushel") . Such an 

 arrangement is not known in other Salpidae except in the aggregated 

 Cyclosalpa fioridana. 



The gut of the aggregated Ritteria amboinensis (fig. 31) is very 

 similar to that of the solitary form. It is a loop with the wide 

 esophageal aperture on the right and the 

 anus above it on the left. At the point of 

 union of esophagus and intestine there is 

 a large rounded swelling on the left side 

 (fig. 33, B, st), which Ihle calls the "stolo- 

 blast" or "eleoblast." 2 Its connections are 

 not clearly shown and its nature is doubt- 

 ful. It may correspond to the problematic 

 organ "q" found in a similar position in the 

 solitary form (fig. 29) or it may be a caecum, 

 though, if it were either, Ihle, whose work 



• j. i , i j , n Fig. 34.— Ritteria amboinensis, eye 



is so uniformly accurate, would naturally AND GANGLION OF AN AGGREGAT ed 

 have so described it. The gut is a little zoom, x iso diameters, from 

 more compact in the aggregated zooid than PSTEIN 

 in the solitary form. It could perhaps be called a "nucleus." 



The eyes of the aggregated Ritteria amboinensis (fig. 34) are figured 

 by Apstein (1904) with sufficient detail to allow some comparison 

 with other species. The larger dorsal eye shows the anterior and 

 posterior divisions characteristic of the true Salpas. In the posterior 

 region the rod-cells are dorsal to the pigment; in the distal region 

 they are ventral. One familiar with the eyes of other species must 

 doubt the accuracy of Apstein's drawing, as to the arrangement of 

 the rod-cells in the basal portion of the eye. They probably should 

 lie with their long axes more nearly vertical. Behind the large dorsal 



> Right or left according to the position on the stolon (Ihle). 



* Of course the aggregated zooid has no stolon rudiment and no eleoblast. 



