244 



RITTER 



Mantle. — Very thin throughout ; circvilar muscle fibers absent except 

 in a narrow, weak sphincter for each siphon. Eight or ten weak lon- 

 gitudinal muscle bands on each side, running obliquely across the 

 thorax, antero-ventrally to postero-dorsally ; anastomosing sparingly 

 anteriorly, and becoming spread out into a thin layer apparently 

 increasing somewhat in number posteriorly, in the abdominal region. 



Branchial apparatus. — Siphons long and prominent, both deeply 

 and regularly six-lobed, the lobes expanded. Tentacles about twelve, 

 all nearly equal in length and rather long ; placed in a close cluster 

 near the siphonal opening. Peripharyngeal field broad (p1. xxx, fig. 



25)- 



Eight series of stigmata, about thirty-five in each half-series ; stig- 

 mata exceedingly regular in form, rather long and narrow. Internal 

 membranes, on the circular vessels, broad. Dorsal languets about as 

 long as branchial tentacles, broad at base, shading off into the internal 

 membranes of the branchial sac to which they correspond in number. 

 Endostyle rather narrow. Postero-ventral corner of the sac produced 

 backward, the esophagus issuing from the postero-dorsal angle. The 

 whole branchial apparatus quite transparent, and usually very little 

 contracted in preservation. 



Digestive tract. — Esophagus long and narrow, the length more 

 than twice that of the branchial sac. Stomach long and narrow, 

 about 4 mm. long, by 1.5 mm. broad; cylindrical, the wall with about 

 six regular, longitudinal folds. Loop of the intestine extending but a 

 short distance behind the stomach ; very narrow. Rectal portion of 

 intestine soon joining the esophagus and running close along with it 

 through the narrow portion of the body. Whole posterior end of in- 

 testinal loop so embedded in the food material of this part of the abdo- 

 men as to make study of it difiicult. 



Reproductive organs. — Situated in the intestinal loop ; ovary 

 composed of numerous cylindrical, often anastomosing, branches. 

 No specimens in reproductive activity at hand. 



The question of the affinities of this striking species is very puzzling. 

 For a time I was much inclined to consider it a Stereoclavella rather 

 closely related to S. australis Herdman, the general character of the 

 colony and especially the freedom of many of the thoraces apparently 

 justifying this view ; and, although I now regard it as more closely 

 allied to Distotna than to any other genus, its kinship with Stereocla- 

 vella is undoubted. The combination of Distomid and Clavelinid 

 characters in this species furnishes additional evidence, of which so 

 much has been forthcoming during recent years, of the close relation- 

 ship between the Distomidae and the Clavelinidae. 



