134 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



aperture, and with edge divided into several finger-shaped promi- 

 nences, ventral half of aperture margin quite plain. Atrial aperture 

 distinctly 6-lobed. Siphonal musculature consists of only circular 

 sphinctors. A pair of rows of short transverse muscles are on both 

 dorsal and ventral sides. Transverse muscles 30-35, on right side of 

 endostyle, confined to anterior half of body anterior to level of distal 

 one-third of intestine ; about 60 transverse muscles on left side of endo- 

 style along its whole length. Approximately 40 transverse muscles 

 on right side of the dorsomedian line along whole body length and 

 about 30 on left side of the dorsomedian line in the anterior half of 

 the body and along left side of the intestine. Also several transverse 

 muscles found on dorsomedian line just behind atrial siphon, being 

 miited in a zigzag-fashion. Basal part of the branchial siphon sur- 

 rounded with about 20 short longitudinal muscles. A thin vascular 

 vessel issues from posterior end of body and proceeds deeply into 

 peduncle. 



Posterior end of branchial sac reaches nearly to rear of body. From 

 54-57 inner longitudinal vessels on each side near the middle of sac, 

 transverse vessels arranged in the order — thick p thin p thick — (where 

 p represents the parastigmatic vessel) ; one to three stigmata in a 

 mesh. Inner longitudinal vessels supported at tip of many support- 

 ing processes, but devoid of papillae. Tentacles about 40, larger and 

 smaller ones differentiated, may reach 80 when minute ones are counted. 

 Generally tentacles on dorsal side larger than on ventral side. Cili- 

 ated groove C-shaped; dorsal languets tentacle-shaped, about 100 in 

 examined specimens. Esophagus very short, opens at dorsoposterior 

 corner of branchial sac. Entire alimentary canal ascending ; stomach 

 small, one-sixth to one-seventh of the whole canal, roughly elliptical 

 in outline, and situated obliquely; about 15 distinct longitudinal pli- 

 cations discernible on surface. Anus situated slightly anterior to 

 middle of body, its margin cut into a dozen lobules. A distinct ovi- 

 duct runs along dorsal side of intestine from level of pyloric end of 

 stomach to that of anus; ovarian tissue develops along posterior half 

 of this duct. Testicular follicles minute, spread along dorsal side of 

 stomach and proximal half of intestine. A vessel with a conspicuous 

 swelling near its anterior end bridges the middle of dorsal side of 

 stomach and intestine at the level of proximal one-third. 



Remapjks. — The present descriptions differ from Van Name's orig- 

 inal (1918) in the number of transverse body muscles (20-30 in Van 

 Name's descriptions) and the appearances of the branchial aperture 

 and the stomach (no description is given by Van Name of the longi- 

 tudinal plications of the stomach). However, reexamination of Van 

 Name's type specimen revealed that such differences were due to 

 somewhat imperfect condition of the type specimen, and it was con- 

 firmed that the present specimens were identical with Van Name's 



