560 
Fig. 
7 
GEOLOGICAL SURVEY OF THE TERRITORIES. 
EXPLANATION OF PLATE XXIII. 
ARTEMIA GRACILIS Verrill (from New Haven), details. 
. Artemia gracilis Verrill. Head, showing the relation of the brain to the eyes, 
optic nerves, and ocellus (ocel), with the stomach and liyer; md, mandible; 
gl, rudimentary shell-gland. 
. Front of the body, showing the circulation of the blood; ht, heart; the dots 
and arrows indicate the course of the blood-currents; int, intestine. 
. End of the same individual represented by Fig. 2; ht, end of the heart, with 
the two valves (seen at Fig, 3a); rec, rectum; m, ‘three pairs of muscular 
bands which hold the rectum in place. 
. Portion of the heart during action; the arrows on each side point towards 
the ostia or valvular openings; the blood dises are represented within 
the heart itself; ep.c, epithelial cells inthe walls of the heart; m, muscles 
which hold the heart in place. 
. End of the body; rec, rectum; m, muscles; anus, vent. 
. One of the compound eyes; ‘cone, one of the crystalline cones; retina, the 
black retina; op. 2, the optic nervules; opn, the main optic nerve; 7. 
m, retractor muscle of the eye; g.op, ganglion opticum, consisting of gang- 
lionic cells, X 4 B. 
Circulation of the blood in a foot, the dots representing the blood discs; the - 
arrows indicating the course of the blood. 
Drawn from the living specimens, with the camera lucida. by the author. 
