Terminal phalanges sometimes clawed. Carpus and tarsus osseous or cartilaginous, usually the latter. Ribs never attached to a sternal apparatus, single or double headed or intermediate, long and curved or short and straight. Articulation with vertebral column inter- or intra-central. Respiration both branchial and pulmonary; branchiæ persistent and osseous in some forms. Development by metamorphosis either in the egg membrane, on the back of the mother, or in the water. No amnion or allantois. Heart with a single ventricle and 3 or 4 pairs of aortic arches; postcava always present in the recent forms. DEFINITION OF SUBCLASS EUAMPHIBIA, MOODIE, 1909. COAL MEASURES TO RECENT. (World-wide distribution.) Moodie, Trans. Kans. Acad. Sci., 1909, p. 243. Moodie, Geol. Mag., n. s., Dec. V, vol. VI, p. 220, May, 1909. The present group was established for the reception of the Branchiosauria and their descendants, the Caudata, with the related forms, the Apoda. The Salientia are included provisionally, since there is no evidence of the origin or relationship of this group of animals to other Euamphibia save that they have attained the same stage of evolution. They are in no way closely related to any known group of Amphibia, recent or extinct, but they stand on the same plane of development as the Caudata and present similar structures, _i.e._, a single ventricle in the heart, external branchiæ in the young, a glandular skin, perichondral bone, and a large parasphenoid. The origin of the Salientia is a puzzle and must remain so until further paleontological evidence is forthcoming. Wyman, Cope, and the writer have all remarked on the similarity of structure between the Salientia and the single known specimen of _Pelion lyelli_ Wyman from the Linton, Ohio, Coal Measures. The subclass Euamphibia may be defined as follows: Aquatic or terrestrial Amphibia; development by metamorphosis; external branchiæ present in the young; bones almost entirely perichondral; carpus and tarsus never ossified; osseous pubis absent; vertebræ usually amphicœlous with persistent notochord; ribs short and straight or flat and slightly curved, or absent; digits 4 in the hand and 5 in the foot; skull never grooved or pitted, nor cut by the lateral-line canals; lateral-line organs present in the skin; sclerotic plates present or absent; tail long and flattened or absent. Ribs in _Triton walthi_ are secondarily long and curved. DEFINITION OF THE ORDER BRANCHIOSAURIA LYDEKKER, 1890. COAL MEASURES AND PERMIAN OF NORTH AMERICA AND EUROPE. Lydekker, Cat. Fossil Reptilia and Amphibia, pt. IV, p. 208, 1890.