174 REPORT—1874. 
Hi. ACIEDENTATUS, Dawson. 
About twice as large as the last species. “Its teeth are very different in form. 
Those on the maxillary and lower jaw are stout and short, placed in a close and 
even series on the inner side of a ridge or plate of bone. Viewed from the side 
they are of a spatulate form, and present a somewhat broad edge at top... . Viewed 
in the opposite direction they are seen to be very thick in a direction transverse to 
that of the jaw, and are wedge-shaped. There are about forty on each side of the 
mandible, and about thirty on each maxillary ” (Dawson). Pulp-cavity relatively 
smaller than in H. Lyelli. 
Locality. Coal-measures of South Joggins, Nova Scotia. 
References. Owen, Q. J. Geol. Soc. vol. xviii. ‘p. 239, t. ix. figs. 7 a, 9 [1862].— 
Dawson, Acadian Geology, 2nd, edit. p. 376, fig. 145 [1867]. 
H. Wyant, Dawson. 
Teeth bluntly conical, and fewer in number than in the other species. The 
remains hitherto found have belonged to very small individuals, not exceeding 4 or 5 
inches in length. They are too scanty to admit of precise definition of the species. 
Locality. Coal-measures of South Joggins, Nova Scotia. 
References. Owen, Q. J. Geol. Soe. vol. xviii. p. 240, t. ix. figs. 8, 11, 12 [1862}. 
—Dawson, ibid. vol. xix. p. 471 [1863].—Jd. Acadian Geology, 2nd edit. 
p. 378, fig. 146 [1867]. 
Hylerpeton, Owen. 
Teeth. Relatively larger than in Hylonomus or Dendrerpeton, conical-pointed ; 
dentine non-plicate. 
Fragments of ribs, a few centra of caudal (?) vertebra, the bones of a foot, and a 
few ovate bony scales are attributed to the same genus by Dr. Dawson. 
H. Dawsontr, Owen. 
Locality. South Jogzins, Nova Scotia. 
References. Owen, Q. J. Geol. Soc. vol. xviii. p. 241, t. ix. fig. 16.—Dawson, 
Acadian Geology, 2nd edit. p. 380, fig. 147 [1867]. 
ANALYSIS OF CHARACTERS OF LABYRINTHODONT GENERA. 
Skull elongate; length more than once and a half the greatest breadth. 
Trematosaurus, Gonioglyptus, Loxomma, Pteroplax, Archegosaurus Decheni, 
Lepterpeton. 
Skull broad; length not more than once and a half the greatest breadth, 
Mastodonsaurus, Capitosaurus, Metopias, Dasyceps, Anthracosaurus, Brachyops, 
Micropholis, Rhinosaurus, Bothriceps, Zygosaurus, Batrachiderpeton, Pholido- 
gaster ?, Archegosaurus latirostris, Urocordylus*, Keraterpeton. 
Skull triangular, with rounded snout. 
Mastodonsaurus, Capitosaurus, Eurosaurus, Trematosaurus, Gonioglyptus, Metopias, 
Dasyceps, Anthracosaurus, Loxomma, Zygosaurus, Archegosaurus, Lepterpeton, 
Urocordylus, Dolichosoma. 
Skull parabolic. 
Brachyops, Micropholis, Rhinosaurus, Bothriceps, Batrachiderpeton?, Dendrerpeton, 
Skull polygonal, with projecting postero-lateral cornua. 
Keraterpeton. 
Skull much contracted in the frontal tract, expanded and truncated behind, 
with postero-lateral (epiotic) cornua. 
Pteroplax. 8 
* Not including the epiotic cornua in the length of the skull. 
