PLATE 3 
EXPLANATION OF FIGURES 
Nectonemertes mirabilis 
4 Ventral view of male individual, showing the thin lateral margins, hori- 
zontal fins, and caudal fin. The position of the mouth is also shown. X 1}. 
5 Lateral view of body, showing its adaptation for swimming. X 1}. 
6 Portion of transverse section of body anterior to tentacles, showing sections 
of four spermaries (sp), cut in different planes. In two of the spermaries the 
seminal vesicles (sv) and spermatic ducts are shown. The spermaries encroach 
to such an extent on the other tissues as to force the lateral nerve (Jn) and the 
diverticula of the intestinal caecum (icd) close against the dorsal wall of the body; 
lv, lateral blood-vessel; par, parenchyma; mc, muscular layer of spermary; Im, 
longitudinal, and cm, circular muscular layers of body wall; bm, basement layer. 
The epithelial covering of the body is missing. X 70. 
7 Terminal portion of seminal vesicle and spermatic duct showing mass of 
mature spermatozoa (spz’) ready for discharge through genital pore. X 200. 
8 Half of transverse section through caudal fin, showing posterior cominis- 
sure of lateral nerves (/n’) between and above intestinal diverticula (7d) and the 
series of dorsoventral muscle bundles between dorsal and ventral body walls. 
Sea); 
9 Portion of transverse section through posterior extremity of body, showing 
extreme development of dorsoventral muscles in the caudal fin, with their nuclei 
lying midway between the two ends of the fibers; 7, rectum. X 50. 
480 
