Howard Ayers and Julia Worthington 331 
layer, and partly in the middle one. The nerve enters them on the side, 
not far from the proximal end. There are comparatively few of these 
cells in the tentacles, and these few are comparatively small; in the skin 
of the head they are much larger and more numerous. 
THE LATERALIS ENDINGS. 
Although numerous investigators have searched for lateral line organs 
in Bdellostoma, both the organs and their canals have hitherto remained 
a... 
__ Dm. 
Sp. 
Pig. &. Fig. 6. 
Fic. 5. Side view of head of young Bdellostoma, 11 inches long, preserved 
in chronic acid. a. l= anterior lateral line canals, b. m.— body musculature, 
h. m.=head musculature, ».—notochord, p. h.—pharynx, p. 1.—=posterior 
lateral line canals, sp.—spinal cord. X 2%. 
Fig. 6. Dorsal view of same head. a. J.=anterior lateral line canals, 
b. m.=body musculature, h. m.—|head musculature, n.=notochord, ph.= 
pharynx, p. /.—posterior lateral line canals, sp. spinal cord. X 2%. 
undiscovered. ‘The presence of lateral line canals in Bdellostoma is ex- 
ceedingly interesting and noteworthy. ‘The sense organs belonging to 
the Acustico-lateral system have been long recognized as present in the 
Petromyzonts, but in the Bdellostomids these structures have eluded all 
observers. Their existence in the latter forms is interesting and important 
because it demonstrates the presence of the surface organs from which 
