NEW ECHIUROID AND SIPUNCULOID WORMS—FISHER 365 
general coelom, one between each pair of longitudinal bands, form 
regular transverse series following the lacunae between the muscle 
bundles of each annulus. 
The retractor muscles originate close to the nerve cord, somewhat 
anterior to middle of postintrovert region and span three or four of 
the longitudinal muscle bands. Posteriorly the retractors are ventral 
or ventrolateral to the esophagus; anteriorly they become more and 
more dorsal, until in the region of the introvert hooks they cover 
the esophagus and fan out at the base of the tentacles. 
The nephridia are slender, free, and cpen about 10 mm. from nerve 
cord, nearly midway between base of retractors and posterior margin of 
introvert. The nephrostome hasaslightly expanded, crescentic upper lip. 
The long esophagus is attached closely to retractors by lateral 
mesenteries as far back as the sharp bend of plate 13, figure 2. The 
posterior edge of the right mesentery is a muscular cord produced 
for a short distance posteriorly on ventral surface of esophagus, 
while that of left mesentry runs along dorsal side. The dorsal con- 
tractile vessel is slender, without diverticula, and ends in a small 
bulb, where the spindle muscle branches. 
Plate 13, figure 1, shows the relations of esophagus, rectum, and 
spindle muscle. The last sends a branch forward on the esophagus, 
which ends in an attachment to body wall (F’), while the principal 
stem, turning posteriorly, lies within the coils of the gut. There 
is a tiny coecum where the esophagus and the rectum first cross. 
At this point a long slender frenulum (F’) anchors the rectum to the 
body wall at midventral line. The spindle muscle is attached strongly 
to the posterior end of the body. If the intestinal coil had not been 
forced into the inflated part of the specimen, it would have extended 
to + in plate 13, figure 2. The free part of spindle muscle, beyond 
end of intestinal coil, is as long as the constricted posterior region of 
plate 13, figure 2. 
The brain is very far forward, at base of the dorsal tentacles, and 
appears as a transversely elongate yellowish patch without obvious 
detail. 
Color in alcohol: Anterior part of introvert grayish pink, the body 
bleached yellowish and pinkish brown. 
Type.—vU.S.N.M. No. 20911. 
Type locality —Key West, Fla., Chester Thompson collector, 1 
specimen. 
SIPHONOMECUS INGENS, new species 
Puatss 14, 15 
Diagnosis.—Size very large; body slender, either uniform in thick- 
ness, or posterior portion contracted, with an attenuate extremity; 
introvert long; skin smooth, with numerous tiny sunken glands 
