522 MOODIE. [VoL. XIX. 
the canals. On the mandibles, the operculo-mandibular canal 
is well-marked (Figs. 9, 9a). The canal, apparently, has 
a course completely around the mandibles, although the ante- 
rior portion of each mandibular ramus has been broken and 
lost. However, at the point where the ramus is broken the 
canal is still strongly marked. The canal has its course, for 
the most part, near the middle of the rami, but as it approaches 
the posterior angle of the mandible it suddenly changes its 
course and drops down to the lower edge only to rise again 
and to come out strongly marked near the median plane on the 
posterior angle of the mandible. On the dorsal surface of the 
skull (Fig. 10) there are faint traces of the canals and on the 
Fic. ga.—The mandibles of Diplocaulus magnicornis Cope as seen from 
below. The operculo-mandibular canal at the arrow. One-half natural 
size. 
edges the infraorbital is clearly marked. The arrows on the 
skull indicate the positions where the canals were detected. 
The long arrow points to a doubtful indication of the supra- 
orbital canal. The infraorbital is clearly marked where it is 
preserved, but the premaxillary region of the skull is lost so the 
entire extent of the canal cannot be determined. 
On the skull of Tuditanus tabulatus Cope (in the Zoological 
collection of Columbia University, New York City) there are 
evidences of a nearly complete system of canals (Fig. 8). The 
fore part of the skull anterior to the transverse line has been 
lost so that portion is unknown since the species is represented 
by a single specimen. The occipital cross-commissure is rep- 
