160 
insertion of the muscles it 
ZOOLOGY. 
enlarges, but there is no true 
stomach ; it is about twice the length of the body, and is bent 
Fig. 110.—Anatomy of Phascolosoma 
Gouldii, cut open, with the flaps pinned 
@, cesophagus ; a7’, two short 
muscles ; pr, two long retractor mus- 
cles; v, next to a dark line the right 
side of the long cesophagus indicating 
the water-vascnlar tube; m, nervous 
‘cord ; 8, segmental organs ; the long, 
twisted intestine returns, ending at a 
ings- 
down. 
Natural size.—Drawn by J. S. 
ley. 
and twisted on itself, ending 
dorsally in a vent marked by an 
external wart, on the anterior 
third of the body. Near this 
point is situated a pair of large, 
long, slightly twisted segmental 
organs(s)the free ends of which 
flare slightly. The nervous 
system (7) forms an cesophageal 
ring, and from it passes a well- 
marked ventral single cord, 
from which at short intervals 
pass off small short lateral 
nerves. The vascular system 
is represented by a circular 
vessel lying next to the ner- 
vous esophageal ring, sending 
branches into, or at least in 
communication with, the cavi- 
ties of the tentacles, and from 
the ring passing along and in- 
timately connected with the di- 
gestive tract, forming a ruffie- 
like organ (v), ending at a point 
nearly opposite the vent (qa). 
Prof. Greef finds that the vas- 
cular system of Echiurus con- 
sists of two main vessels, 7. ¢., 
a dorsal and a ventral vessel ; 
the former extending along the 
alimentary canal, and sending 
a branch to the proboscis, where 
it divides into two branches, 
each uniting with the ventral 
vessel. The blood is pale yel- 
lowish, with corpuscles. The 
blood-system of the Gephyrea, then, is homologous with 
