mm. Length of entire animal 49 Length of head in median line 6.5 Width of head at posterior border 8 Length of orbit 2.5 Width of orbit 2 Interorbital space 2 Length of the vertebral column 33 Length of the vertebral centrum in dorsal series 0.5 Length of trunk from base of skull to sacrum 22 Length of rib 1.5 Length of scapula 3 Maximum width of clavicle 2 Length of humerus 2.5 Length of ilium 1.5 Length of femur 2 Length of tibia 1.5 Length of tail impression 21.5 Width of tail impression at base 4 =Genus EUMICRERPETON Moodie.= Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 330, 1912. Type: _Eumicrerpeton parvum_ Moodie. The genus is established on three well-preserved specimens representing nearly the entire anatomy. The generic characters are found in the very broad posterior table of the skull, with its short length, reduction of tympanic notch, and shortness of body. The body-length of _Eumicrerpeton_ (plate 5, fig. 1) is less proportionately than that of other closely allied genera. Other generic characters are found in the sharp postero-lateral angle of the skull, and it is to be distinguished from _Micrerpeton_, especially, by the short, stumpy limb bones. The narrow, elongate eye, placed close to the edge of the skull, is a character not observed hitherto in the Branchiosauria. The genus is closely allied to _Branchiosaurus_ of Europe. =Eumicrerpeton parvum Moodie.= Moodie, Proc. U. S. Nat. Mus., 40, p. 430, fig. 1, 1911. Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 331-336, pl. 3, figs. 3 and 4; pl. 4; pl. 5, fig. 1; pl. 6, figs. 1 and 2, 1912. Moodie, Amer. Nat., 44, pp. 367-375, figs. 1-4, 1910. Moodie, Science, n. s., XXXI, No. 789, p. 233. Type: Specimen No. 803, Yale University Museum. Other specimens, No. 802, Yale University Museum, and No. 4400, U. S. National Museum. Horizon and locality: Mazon Creek shales, near Morris, Illinois. The impression of the outline of the entire body is preserved (plate 3, figs. 1 and 2) in three specimens, and in all are found molds and impressions of the alimentary canal, which, in one specimen (471), are remarkably complete and instructive. The three specimens will be discussed separately, since they show different features.