No. 802 (471) Yale University Museum: mm. Length of animal 30 Length of skull 4 Posterior width of skull 5 Length of œsophagus 3.5 Length of stomach 6 Width of stomach 1.33 Estimated length of intestine 18 Width across base of tail impression 2.5 Length of tail from base to tip 7 No. 4400, U. S. National Museum: mm. Length of entire animal 45 Length of skull 6 Width of skull 9 Transverse diameter of orbit 1.50 Long diameter of orbit 2.25 Interorbital space 2.50 Diameter of pineal foramen 50 Length of body from back of skull to pelvis 22 Greatest width of body 9 Length of tail 16 Width of tail at base 5 Length of humerus 3 Length of femur 2.50 Length of tibia (fibula?) 1.75 Length of stomach 3 Length of intestine (estimated) 5.6 Width of intestine 1 [Illustration: MOODIE PLATE 4 1 and 2. Vertebræ of _Spondylerpeton spinatum_ Moodie. × 1. 3. Type specimen of _Mazonerpeton costatum_ Moodie. × 1. 4. Type skeleton of Cephalerpeton ventriarmatum Moodie. × 0.9. 5 and 6. The halves of the nodule containing a practically complete skeleton of Amphibians grandiceps Cope. × 1. Originals of above figures in the Yale University Museum. ] =Genus MAZONERPETON Moodie.= Moodie, Kans. Univ. Sci. Bull., vol. VI, No. 2, p. 336, 1912. Type: _M. longicaudatum_ Moodie. The genus is distinguished from other known branchiosaurian genera by the great length of the dorsal region, the elongate tail (plate 5, fig. 2), with its well-developed caudal ribs, the reduction of the tympanic notch, the broad nature of the scapula, the elongate interclavicle, and the slender ilium. The number of dorsal vertebræ is identical with that of _Branchiosaurus_ of Saxony. =Mazonerpeton longicaudatum Moodie.= Kans. Univ. Sci. Bull., VI, No. 2, p. 337, pl. 3, figs. 1-2; pl. 7, fig. 3; pl. 10. 1912. Type: Specimen No. 795 (1234), Yale University Museum. Horizon and locality: Mazon Creek shales, near Morris, Illinois. (Plate 3, figs. 5 and 6.)