The ribs throughout the body are short, heavy, and straight, with, in the dorsal series, a lateral and a distal expansion which is taken as a distinctive specific character. Judging from imperfect impressions in the dorsal series, the ribs were attached to a transverse process of the centrum, thus agreeing with other branchiosaurians in this respect. The ribs show a progressive decrease in length from the cervical region to the point of their disappearance on the tail. [Illustration: MOODIE PLATE 5 1. A reconstruction of the possible appearance in life of the Coal Measures branchiosaurian, _Eumicrerpeton parvum_ Moodie, a small, primitive salamander, less than 2 inches in length, based on three specimens from the Mazon Creek Shales. The lateral-line organs are represented as dark bands on the tail, the sense-organs being, apparently, situated beneath specialized pigmented scales, to which is due the preservation of the lines. 2. A restoration, natural size, of the branchiosaurian, _Mazonerpeton_, based on two specimens. The form of the animal is quite salamander-like. It is shown when about to feed on a specimen of _Acanthotelson stimpsoni_, which is said to be a brackish-water crustacean. The branchiosaur and crustacean may possibly have inhabited the same body of water. ] The pectoral girdle is represented by two elements, one of which is certainly the right clavicle, and the other is possibly the left clavicle, though its form is somewhat distorted by pressure. Both elements are in the form of an elongate spatula with the dorsal surface greatly concave and the inner end acuminate. The right humerus is imperfectly preserved, though the impression allows one to gain an exact idea of its form. It lies under the right clavicle. Its ends are truncate with a contracted shaft and expanded extremities; the bone was apparently hollow. [Illustration: Fig. 15. A. Impression of _Erierpeton branchialis_ Moodie. _bb_, basibranchial; _hyp_, hypohyals; _m_, mandible; _d_, body impression. × 3. B. _Eumicrerpeton parvum_ Moodie. _a_, anus; _f_, femur; _h_, humerus; _in_, intestine; _l_, liver; st, stomach; _r_, radius; _u_, ulna. × 3.3. C. Larger specimen of _Eumicrerpeton parvum_ Moodie. _a_, anus; _d_, dorsal lateral-line; _h_, humerus; _in_, intestine; _ml_, median lateral-line; _st_, stomach. × 2.6. D. Skeleton of _Erpetobrachium mazonensis_ Moodie. _cl_, clavicle; _h_, humerus; _r_, radius; _sc_, scapula; _u_, ulna. × 2. E. Rib of _Mazonerpeton costatum_ Moodie. × 2.5. Originals in the Yale University Museum. ]