﻿420 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



convex, closely placed; tentacles relatively large, profusely branched, 

 in fours; nephridia opening a conspicuous distance posterior to anus; 

 gut-fixing muscle F^ attached to ascending intestine; gonad on retrac- 

 tor muscles anterior to their base; Polian tubules branched, numerous. 

 Length of trunk to anus 24 mm.; length to base of tentacles 30 mm.; 

 tentacles 4 mm.; breadth of introvert 3.5 to 4 mm. 



Description. — Size small; the body short, the trunk thick set; the 

 thick cylindrical introvert about one-fourth the body length, its 

 anterior third a perfectly smooth, translucent collar, while the rest 

 of the introvert, which is whitish, is crowded with minute convex 

 glands. The body is warm sepia with a darker zone including anus 

 and nephridiopores and one at the posterior extremity. It is very 

 closely covered with low-convex glands, 0.08 to 0.1 mm. in diameter, 

 similar in form to those of introvert, and more or less in transverse 

 serial alinement. They are rather nondescript under high magnifi- 

 cation by transmitted light (pi. 35, fig. 3). By reflected light the 

 central canal shows as a dark spot. In the darker anal zone the cuticle 

 is thicker and the glands are deeper, crowded, transverse elliptical 

 (0.02 mm. by 0.07 mm.). In a narrower zone between the anus and 

 nephridiopores there are larger, more superficial, transversely elliptical 

 glands which show as inconspicuous brown spots of about two sizes. 



The teutacles branch profusely. One can count four or eight, 

 depending upon the value assigned to each arm. The oral disk has 

 four principal food grooves, each of which divides into two, and each of 

 these goes to an arm. If a sagittal plane and one at right angles is 

 drawn (see arrows, pi. 35, fig. 4), each quadrant contains one of the 

 four primary food grooves, and one tentacle with two arms, or two 

 tentacles, depending upon the point of view. But the two arms in the 

 upper right quadi'ant branch a little sooner than the others, which 

 gives them more the appearance of primary tentacles than is the case 

 with the two upper left. Hence one might easily reckon the number as 

 five, if reference were not made to the food grooves. The tentacles are 

 light brown. The nuchal organ has a lengthwise V-shaped depression. 



The retractors are large and attached at the beginning of the ter- 

 minal fifth of body. The line of attacliment is straight and very broad, 

 and the inner ends nearly meet under the nerve cord, which here gives 

 off numerous nerves to the muscles. The muscles are separated practi- 

 cally to the nuchal organ. The spindle muscle foUows the usual 

 course from its attaclmient above the rectum. The wing muscles are 

 very broad, the left somewhat broader than the right. Fixing muscles 

 F', F^, and F^ are attached about the same as in Dendiostomum dy sen- 

 ium, F^ being attached to the uppermost coil of the ascending in- 

 testine while F^ is attached opposite the coecum. The longitudinal, 

 inner muscle layer has a satiny luster and is crinkled transversely. 

 No oblique strands are observable. 



