ORIGIN OF JAW APPARATUS 371 
J. Miller coveringa general survey of the anatomy of Bdellostoma, 
Ayers and Jackson on the anatomy of the skeleton, Julia Worth- 
ington on the head nerves, EK. P. Allis on the skeleton, nerves, 
and muscles of the head, F. J. Cole on the skeleton and muscles 
of Myxine, and P. Firbringer on the skeleton, nerves, and 
muscles of Myxine. 
The jaw apparatus of Bdellostoma consists of a pair of den- 
tigerous jaw plates located in the buccal cavity and lying above 
a large cartilaginous plate which forms a support for it, of a 
pair of bars starting from near the sides of the jaw plates, but 
Fig. 22 Front view of face of adult Bdellostoma, with jaws protruded, show- 
ing external relation of tentacles to narial and buccal apertures. With the hyoid 
as a base, the jaw bars pass upward giving off the tentacles and framing in the 
buccal opening. The dotted line on the left side indicates the course of the 
distal part of the jaw bars in front view. 
attached to the large support plate which lies ventrad of the jaw, 
and which run forward and upward in the lips of the buccal 
cavity (figs. 22, 28, 24, 25, 26, 27, 29). They attach at their 
distal ends to the lateral borders of the nasal tube near to its 
anterior end. The first part is the basal or proximal part of 
the Amphioxine jaw bar and the second part is the distal section. 
The proximal part has been transformed into a tooth-bearing 
protrusible jaw, while the distal part serves as the skeleton of 
the lips of the buccal aperture and is the only part bearing 
tentacles in Bdellostoma. The number of tentacles is reduced 
to four, two of which (the first and third) are unit structures 
