22 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



is near the ventral end of the last body muscle. These connective 

 tissue fibers probably establish a functional connection between the 

 ventral end of the last body muscle and the visceral muscle, so that 

 their contraction probably produces much the same effect that 

 would bo secured if they were actually continuous. The last body 

 muscle is similarly continued into the visceral region in Cyclosalpa 

 ajjinis (pi. 3, fig. 10) C.floridana (pi. 5, fig. 15), and C. baTceri (pi. 8, 

 fig. 22). None of these, however, shows a separate visceral muscle. 

 There is nothing comparable in C. virgula (pis. 11, 12, and 13). 



The intermediate muscles, which in older zooids are in contact 

 ventrally, are continued as a strong double muscle through the 

 peduncle almost to the stolon (or core of the whorl). On each side 

 of the body the first body muscle unites with the third to form a 

 broad band of muscle, which is similarly continued through the 

 peduncle toward the core of the whorl, but it is not prolonged so 

 far into the peduncle as are the intermediate muscles. There is 

 one of these posterior peduncle muscles on each side. They are 

 entirely independent of each other. 



The sphincter muscles of the atrial siphon are unbranched. Each 

 is a complete hoop. The first is a strong muscle and is connected 

 with the last body muscle by a horizontal band which functions as 

 an atrial retractor. 



The gill is as in the solitary form. The outline of the aperture of 

 the dorsal tubercle is shown in figure 4 (pi. 1). No comment is 

 needed upon the endostyle and peripharygeal bands. 



The gut of the aggregated form differs from that of the solitary 

 form in the presence of but one caecum and in the ventral position 

 of the intestine, below the endostyle, the anus being well forward 

 toward the front of the pharynx. It would seem that this position 

 for the anus would be very disadvantageous, discharging feces in 

 such a manner that they would become entangled in that current of 

 mucus which by action of the cilia is constantly being carried for- 

 ward on the endostyle, up on the peripharyngeal bands and back 

 on the gill to the esophageal aperture. 



The heart (h.) lies to the right of the intestine, a little higher up 

 than in the solitary form. 



The ovary is in front of the fourth body muscle, the oviduct lead- 

 ing forward almost to the third body muscle. The elongated testis 

 lies between the endostyle and gut (pi. 2, fig. 5 t.). Its duct opens 

 near the anus, as in other Cyclosalpas, but in this species the posi- 

 tion of both apertures is further forward than in any other aggregated 

 form in the Salpidae. 



The ganglion is flattened on its dorsal surface where lies the large 

 eye (pi. 2, figs. 7 and 8). The ganglion contains two pairs of minute 

 hemispherical eyes, each of which is composed of about 25 rod cells 

 (fig.O ,p. 23) . The posterior pair lie one on side each of the middle point 



