354 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, ®f 
latter extends to the beginning of the intestine, which is marked by 
the ciliated groove. The long intestine, which is filled with ellip- 
soidal pellets of mud, has no features characteristic of this species. 
The precloacal intestinal coecum is very tiny. 
An unusual feature of the vascular system is the prolongation of 
the dorsal vessel beyond the fore-gut onto the intestine. This “heart,’’ 
as it is sometimes called, passes from the dorsal side of the fore-gut to 
the ventral side of the intestine, which it practically envelops. As 
will be seen from the figure, the dorsal mesenteries (pl. 9, M') of 
the intestine actually are attached to the ventral side of the body wall 
near the nerve cord. This results in a twisting of the intestine where- 
by the dorsal blood vessel becomes ventral in position, while the cili- 
ated groove, which should be ventral, becomes dorsal. Jn conse- 
quence the neurointestinal blood vessel (B?, B#*) is dorsal in posi- 
tion when it leaves the intestine, instead of ventral as in most echiu- 
roids. The ciliated groove passes through the ring vessel (B?), a 
very rare occurrence. In the neurointestinal vessel is a small pas- 
sage for the interbasal muscle of setae. 
Color in life, reddish. 
Type.—U.S.N.M. No. 20801. 
Type locality.—-Beaufort, N. C., June 1940. Dr. Olga Hartman 
collector, 2 specimens. 
Remarks.—A specimen in poor state of preservation was dredged 
by the Fish Hawk in Chesapeake Bay, off Rappahannock Spit 
(station 8846) August 23, 1920, 12.8 fathoms. 
Phylum SIPUNCULOIDEA 
Genus SIPUNCULUS Linnaeus 
SIPUNCULUS POLYMYOTUS, new species 
PiateE 10 
Diagnosis.—Differing from S. nudus, which it resembles in general 
form, in having 53-61 longitudinal muscle bands instead of 32-33, 
a shorter introvert, and a fasciculate cerebral organ and in lacking 
a conspicuous anterior lobe at base of nephridium. 
Description.—Length 300 mm.; introvert 25 mm.; thickness of 
cylindrical body 28-38 mm.; of base of papillose introvert 15 mm. 
Longitudinal muscle bands of type 53 to 55; muscle annuli 200, 
much broader at extremities of body than at middle. The posterior 
extremity may be either very blunt or bluntly pointed (as in robustus). 
The introvert is relatively short and closely beset with posteriorly 
directed, blunt, small papillae, which decrease in size toward the 
mouth. The largest, on the posterior part of the introvert, are 0.5 
to 0.75 mm. long. The four tentacles are relatively small, the two 
