30 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



abdomen of Ritter) as a single broad band (y.) comparable probably 

 to the slightly developod tip of the fused ends of the fourth body 

 muscles in Cyclosalpa pinnata plus the visceral muscle which in C. 

 pinnata is not continuous with this. The fourth body muscle on each 

 side, near its ventral end, branches, giving rise to a small band which 

 runs back into the visceral region (postabdomen). 



The atrial retractor and sphincter systems, in the two species 

 Cyclosalpa affinis and C. pinnata, are similar except in two minor 

 points: first, in C. affinis the atrial retractor connects with the pos- 

 terior branch of the fourth body muscle instead of connecting above 

 its point of branching; and, second, the delicate sphincters branch 

 form a slight network. 



The gut differs in position and structure from that of the aggre- 

 gated Cyclosalpa pinnata. It is in the form of a wide loop, the anal 

 aperture being at the left of the esophagus, instead of far forward 

 below the endostyle. There is a more marked stomach-like enlarge- 

 ment of the gut in this species. No caecum is present. The gut 

 seems to be approaching the condition observed in the true Salpae, 

 sensu strictu, in its curved form (though it is not yet a "nucleus"), 

 in the absence of a caecum, and in the presence of a slight 

 stomach enlargement. An intestinal gland is present, its duct stretch 

 ing from its aperture into the stomach, across the empty space of the 

 loop, the branches of the gland itself being along the distal half of the 

 intestine. The crowded condition in Cyclosalpa pinnata, caused by 

 the close approximation of the intestine, endostyle, and testis, makes 

 the intestinal gland difficult to observe in that species. 



The testis lies along the intestine as in Cyclosalpa pinnata, but the 

 looped condition of the intestine allows it more space and it is a little 

 more stocky. The vas deferens opens near the esophageal aperture. 

 The ovary is in a position similar to that which it occupies in Cyclo- 

 salpa pinnata. The heart lies beneath the posterior end of the endo- 

 style, in a slight ventral protuberance of the body. 



The outline of the aperture of the dorsal tubercle is shown in 

 figure 12, plate 4. The ganglion and its ventro-lateral outgrowths 

 and the neural gland are so similar to those of the aggregated Cyclo- 

 salpa pinnata as to need no description. The large eye, on the other 

 hand, shows a few significant divergencies from that of the aggre- 

 gated Cyclosalpa pinnata. Its long axis points not horizontally for- 

 ward as in C. pinnata, but forward and fifteen degrees upward (pi. 

 4, fig. 11). The rotation of the developing eye has not gone so far 

 as in C. pinnata. The plug of optic cells is smaller than in the latter 

 species and is less distinct from the arch of the horseshoe. The 

 posterior portion of the eye is not divided into two swollen limbs, 

 but is continuous from side to side and is thinner than are the limbs 



