NEW ECHIUROID AND SIPUNCULOID WORMS—FISHER 363 
here the canal passes backward along muscle 9 for an unknown 
distance before starting the spiral. The spirals are well established 
in the posterior half of the body 
Nephridia are long, slender, and except for a short terminal portioh 
are closely attached to maacind 
The nerve cord is slender, ‘on than half the width of muscle 1. 
Anteriorly the rather slender paraneural muscles arise from muscle 
1, 4-5 mm. behind nephrostome. The bilobed cerebral ganglion has 
across the front a prominent frons (cerebral organ) composed of 
short bushy elements, exactly resembling a very tiny cauliflower. 
Color in alcohol faded yellowish; the La Paz specimen is gray 
varied with straw color. 
Type locality—Esmeraldas, Ecuador. 
Specimens examined.—Panama: (Hassler Expedition), 3 specimens. 
La Paz, Baja California, Lyman Belding collector, 1 specimen. 
SIPHONOMECUS, new genus 
Diagnosis.—Resembling Phascolosoma but very large, the longi- 
tudinal muscle layer divided into stout bands, either freely or rarely 
anastomosing; between the strong circular muscle bands there are 
discontinuous, transverse, coelomic lacunae, which connect with sub- 
cutaneous pockets, longitudinally oriented, one for each rectangle 
of the skin: retractors 2 or 4; anus a short distance behind nephridi- 
opores; nephridia slender, free; spindle muscle strong, firmly an- 
chored at posterior end of body; type with simple spinelets on intro- 
vert; tentacles similar to those of Phascolosoma. 
Genotype, Siphonomecus muliicinctus, new species. 
SIPHONOMECUS MULTICINCTUS, new species 
PuaTE 13 
Diragnosis.—Size very large; longitudinal muscles of postsiphonal 
region divided into anastomosing bundles; retractors 2, originating 
near middle of body; introvert about one-third length of body, its 
anterior end with about 28 circles of very small spines; tentacular 
crown with eight primary divisions, and numerous subdivisions; 
Spindle muscle strong, forked at its origin behind anus, and firmly 
attached to posterior end of body; anus opening far behind introvert 
and a very short distance behind nephridiopores. Total length 510 
mm.; introvert 150 mm.; thickness of body at posterior end of re- 
tractors about 25 mm., and of the terminal 200 mm. (constricted 
and annulated) 10 mm.; breadth of tentacular crown, 7 mm. 
Description—The skin is pale brownish and rather closely peppered 
with low, brown papillae about 0.25 mm. broad. These have a 
circular-convex whitish center about 0.06 mm. broad. They appear 
to the naked eye simply as brown dots, 1 to 4 to each oblong rec- 
tangle of the skin, which is rather coriaceous but not rough. Be- 
