_Hylerpeton longidentatum_ Dawson. Mandible and other bones. Nearly natural size. Erect tree, Coal formation, South Joggins, Nova Scotia. Photograph by Dawson, published through the courtesy of Dr. Arthur Willey. Original specimen in the Peter Redpath Museum of McGill University.] [Illustration: MOODIE PLATE 12 _Smilerpeton aciedentatum_ Dawson. Mandible, portions of skull, scales, and various bones. Nearly natural size. Erect tree, Coal formation, South Joggins, Nova Scotia, photograph by Dawson, published through the courtesy of Dr. Arthur Willey. Original specimen in the Peter Redpath Museum of McGill University.] Vertebræ short, cylindrical, well-ossified, with well-developed zygapophyses and neural spines; ribs strong and much curved, with well-developed division of the proximal ends; pelvis imperfect, but apparently large, with broad ilium. Humerus half the length of the mandible; radius half as long as humerus; femur very large and stout, nearly as long as the mandible; leg bones and phalanges correspondingly stout. The thoracic plate (plate 7) is indicated only by some fragments. The abdominal scales are narrow and pointed (oat-shaped), smooth externally and with a ridge at one side within. The following are the dimensions of the largest specimen: Length of mandible 4.4 cm. Length of largest tooth 5 mm. Length of femur 3.5 cm. Length of tibia 2 cm. Length of humerus 2 cm. Length of radius 1.5 cm. Length of vertebra 6 mm. Length of rib 3 cm. Length of scales 5 to 7 mm. =Hylerpeton longidentatum Dawson.= Dawson, Am. Jour. Sci. (3), XII, pp. 440-447, 1876. Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 640, pl. 42, figs. 86 to 109. Dawson, Proc. and Trans. Roy. Soc. Canada, 1894, XII, p. 74. Type: Specimen No. 3061-6, Peter Redpath Museum, McGill University. There is also a specimen, No. R 440, in the British Museum (393, pt. IV, p. 225). (Plate 11.) Horizon and locality: Coal formation at the South Joggins, Nova Scotia. Head much elongated, with the bones minutely pitted, and with delicate microscopic strife, but not sculptured. Mandibular and maxillary teeth long and acute, pointing backwards, with the apex of their inner sides finely striated; 20 or more in each ramus of the lower jaw; palatal bones with several long, slender teeth and many minute teeth. The mandibles found are not complete, but there are indications that there was an ascending process as in _H. dawsoni_, but less developed. The narrowness of the dentary bone is caused in part by the lower posterior edge being bent inward and by the posterior end being broken off above.