No. 2.] LATERAL LINE IN EXTINCT AMPHIBIA. 515 
lower posterior portion of the infraorbital canal I propose the 
term “jugal canal” (Fig. 1 “f’’), since it lies in great part on 
that element of the skull. The jugal canal is, I believe, a new 
formation in the Stegocephala. I am unable to homologize 
it with anything which I can find occurring in fishes. It may 
be composed of the infraorbital and a portion of the operculo- 
mandibular canal, but of this I am not sure. The most poste- 
rior canal of the stegocephalan skull is homologous with the 
Fic. 2.—Outline of the lateral line canals on the skull of Amia calva. 
Lettering as in Fig. r. After Allis. 
Fic. 3.—Outline of the lateral line canals on the skull of Polypterus. 
After Baur and Traquair. 
supratemporal cross-commissure of Amia as defined by Allis, 
and it is here designated the “occipital cross-commissure”’ 
(Fig. 1 “g’’). Allis (1899) was doubtful as to whether this 
canal could be homologous with the same placed canal in Amia 
and Polypterus, and was inclined to correlate it with a canal 
which occurs in other fishes and which would distinctly change 
the correlations of the cranial elements. There can be no 
doubt, however, that the ‘occipital cross-commissure” is the 
