Howard Ayers and Julia Worthington 333 
The canals are arranged in two groups, an anterior and a posterior one, 
in the dorso-lateral territory of the head, corresponding to the anterior 
and posterior /ateralis nerves by which they are innervated. Figs. 5 and 6 
show the position of these groups on the head. The anterior group of 
canals is composed of four, occasionally three or five short canals, nearly 
equidistant from each other. This group of canals is located on the side 
of the head in front of the eye, of its side of the body. The cephalic end 
of the most ventral canal is slightly caudad of the hind end of the most 
dorsal one (Fig. 5). The posterior group les on the dorsal surface of 
the head and consists of two divisions; the three (occasionally two) 
inner canals run meso-laterad, and the outer ones run at a slight angle 
to the long axis of the body (Fig. 6). 
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Fic. 8. Cross-section of epidermis of young Bdellostoma, 11 inches long, 
close to lateral line canal. Preserved in chromic acid. b—=basement mem- 
brane, m—mucous cell, ¢tube above dermal groove. 3338. 
Cross-sections through the canals show an interesting and rather pe- 
culiar state of affairs, and also a condition that differs according to the 
original preservative used. Fig. 7 is a cross-section through one of the 
dorsal canals of a young hagfish about eleven inches long. The head 
from which it was taken was preserved in formalin. The canal itself 
(Fig. 7, g) is seen as a deep, narrow groove in the outer layer of the 
epidermis. In the figure its bottom is formed by the outer ends of a 
group of long, slender spindle cells (Fig. 7, ¢), grouped to form a fusi- 
form body. In studying serial sections, however, this group of spindle- 
shaped cells is found to extend along the entire bottom of the canal. In 
some sections it extends down to the basement membrane, in others only 
about one-half the distance. There is a distinct line of cleavage down 
the center of this ridge of spindle cells, so that in some sections it sep- 
