AND AXES OF NORTII AMERICA. 15 Mean WVMOM& Linen. Preserved length of ramus (imperfect), 11 Depth at last tooth, Length of exposed tooth, 1.7 Length clentary, 7.3 Depth at coronoid, 3.5 Do. at first tooth, 1.3 In the mandibular ramus of the Hyletpeton dawsoui• there arc according to Owen at least nine teeth ; in the present species there are but seven. SAUROPLEURA, Cope. Proceed. Acad. Nat. Sei. Phil. 1868, p. 215. This genus embraces a single species only, as I at present understand it. The extremities are well developed, and the body is stout and lizard-like. It is represented by but one individual which has been spread ol er a surface of the coal slate, exhibiting ventral armature, dorsal region with ribs, and anterior and posterior limbs. Of skull and caudal vertebra nothing remains. The dermal riblets are arranged as in Urocordylus, i. e. in parallel lines directed obliquely forwards and continuous on the median line, forming there a chevron directed forwards. The striae are not so closely placed as in 0. pectinate, but are separated by grooves wider than themselves. The humerus, ulna and radius, are rather stout, and of a size relative to the body, as in common types of existing sauria; the ulna and radius separate. There is no carpus, but five well developed digits have phalanges in the following numbers, commencing on the inside, 3, 4, 5, 6, 5. The last phalange of the second is obscured, and it is not positive that the number is as given; it is more probable than that it should have been 3. The outer toe has been more slender than the others; the distal phalanges of all the toes ale short conic, as in Salamanders. Thus this form differs much from Amphibamus, where the numbers are 3, 3, 4, 5, 4, showing a lower des elopment of limbs. The ribs are long and curved as in Reptiles, and judging by their distances the vertebra are short; the latter are not well defined but there is no indication of prominent spines of any kind. The pelvic bones and portions of those of the hind limbs are present, but so obscured and confused as not to be made out. Enough remains to show that the hind limbs are considerably longer than the anterior.
