330 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. || 



Tentacular Muscles. — The number of tentacles varies 

 between thirteen and fourteen. Each is provided with two 

 muscles extending along the sides apparently to the tip. 

 According to Davenport, tentacular muscles are unknown 

 in any Entoproct except Urnatella. Comparing Daven- 

 port's drawing (PI. IV, fig. 27) with fig. 9, it will be seen 

 that Urnatella and Myosoma closely resemble each other in 

 this respect. Figure 9 represents a cross-section near the 

 base of three tentacles and the transverse ends of the ten- 

 tacular muscle fibers are clearly shown {tent. m.). Figure 

 10 represents the same in longitudinal section, and the fibers 

 {tent, m.) are seen extending through the length of the 

 tentacles. The attachment of these fibers has not been ! 



definitely made out, but the indications are that they unite 

 with the ectoderm at the base of the tentacular disc. 



Intestinal Muscles. — In addition to the systems of muscles I 



already described, there is an intestino-rectal sphincter. j 



This consists of three or four well defined muscle bundles, ^ 



showing in cross-section in the wall of the intestine. This 

 is also reported for Urnatella. There is besides an anal 

 sphincter, not differing apparently from that described for 

 other Entoprocta, 



The Organs. — The tentacles are ciliated on the inner 

 surface. The atrial chamber is large and its floor is like- 

 wise ciliated. The alimentary tract does not differ materially 

 from that described for other Entoprocts. It consists of 

 oesophagus, stomach, intestine, and rectum, all heavily 

 ciliated except the roof of the stomach, the region of the 

 so-called "liver cells" (figs. 3 and 8, els. I.). Figure 3 

 represents the alimentary tract, but the section is not in the 

 median plane and consequently does not pass through the 

 intestine and rectum. 



No special study has been devoted to the nephridia, 

 although the excretory ducts and pore have been observed. 

 The nerve ganglion with its large nerve trunks is a conspic- 

 uous object, but no minute study of it has been made. Both 

 males and females grow from the same stolon and are indif- 

 ferently intermixed in the colony. The testes and the 



