AND AYES OF NORTH AMERICA. 13 posteriorly as the anterior margin of the orbits. The external nostrils are large and opposite the inner margin of the orbit on each side. This separation of the nares is associated with a greater transverse extent of the premaxil-laries than in some of the genera. These have been set with numerous teeth, judging by their small impressions ; no larger ones have left traces, and no traces of any on the maxillaries. The teeth of the genera before described are all much larger relatively, indicating still further the diversity between them.
A fragment of mandible remains, but without teeth or external surface. It shows a large internal canal.
Neasarenzents. Lines. Total length cranium, 25.5 Width do. three lines behind orbits, 24 Do. between orbits, 7.5 Do. do. flares, 5 Do. oeeipital condyles, 2.2 Do. of supraoeeipital bones, 0 Do. of right parietal, Extent of premaxillaries, 8.7 Length orbit, 0
Measurements
| No. | 1441. | Greatest length of coronoid, about | 220 | mm. |
| " | 1441. | "width""" | 45 | " |
| " | 1441. | ""posterior end of ramus | 70 | " |
| " | 1441. | """anterior""" | 18 | " |
From the Coal Measures at Linton, Columbiana county, Ohio. Discovered by Dr. Yno. S. Newberry. 'When the remainder of the skeleton of this species is known, its generic relations will be better established. Another cranium accompanies the collection, which belongs to a species distinct from the last. The muzzle is not so broadly rounded and the premaxillar) teeth are relative-ly much larger. The sculpture is more delicate with the ridges more acute. The orbits and lines are not defined. The maxillary is well preserved for a length of an inch; its teeth are smaller than the premaxillines ; I count four in a line ; crown simple conic. External surface of maxillary not very strongly sculptured. This species cannot be referred to its genus without further material. I therefore do not name it.
DENDRERPETON ACADIANUM, Owen.
Quart. Jom.u. Geol. Soe. X., 1853, Si. Dawson, Loc. Cit. Coal Measures. Joggins, of Nova Scotia.-
DENDRERPETON OWENII, Dawson. Canadian Naturalist and Geologist, VIII., 161. Coal Measures : as the last.
HYLERPETON, Owen.
HYLERPETON DAIVSONII Owen.
Journ. Geol. Loc. Loud. Loc. Cit. Dawson, Canadian Naturalist and Geologist, VIII., 272. Carboniferous Coal Measures. The Joggins, Nova Scotia. AMER!. PIIILOSO. SOC.—VOL. XIV. 4
