This is the most frequently occurring genus in the Deseado, but is as yet represented only by isolated plates. The genus is distinguished by thick, relatively long and narrow, movable plates, each overlapped by about a third of its length. The plates of the pelvic buckler are shorter and thicker, the exposed surface of each being ornamented by a figure compared by Ameghino to a flask (see fig. 131), which figure is more distinct on the rear, fading away toward the front. On the plates of the pelvic buckler this figure is more accentuated, and from it, on either side, radiate two furrows dividing the surface into several (4 to 5) areas. The entire surface of each plate is irregularly punctate. =Proeutatus lagenaformis= Ameghino P. sp? Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 660. P. lagenaformis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 507. [Illustration: Fig. 131. _A_, movable plate; _B_ and _C_, plates from pelvic buckler—natural size.] On the Chico del Chubut River, west of Puerto Visser, we found nine specimens of this species, all fragmentary, though one consists of over fifty more or less broken plates, mostly from the pelvic buckler. This is the only species of the genus from the Deseado, and corresponds to the description above. A movable plate generally measures about 28 mm. long by 10 mm. wide, and has four large piliferous pits on the posterior margin. A plate of the pelvic buckler varies greatly in size, but is always thick and has two to eight piliferous holes on the posterior margin. A typical plate measures 20 mm. long by 10 mm. wide. =Prozaedius= Ameghino Zaedius Amegh., in part, 1889, Act. Acad. Nac. Cordoba, t. 5, p. 867. Prozaedius Amegh., 1891, Revista Argen. Hist. Nat., t. 1, p. 327. Dasypus Lydekker, in part, 1894, Anal. Mus. La Plata, t. 3, p. 55. Prozaedius Scott, 1903-5, Reports Princeton Patagonian Exp., vol. 5, p. 69. Of this little genus, which is so strikingly like the living _Zaedius_, we found a carapace with ten rows of movable plates in place, parts of four rows of fixed plates from the pelvic buckler, and some caudal vertebrae. The genus is distinguished by its thin plates, there being fourteen bands of movable plates, and eight rows in the pelvic buckler. The movable plates are narrow, each overlapped about a fourth of its length, and have a faint ornamentation, with no piliferous pits except on the posterior margin. The fixed plates are similar, except that they are shorter, and have the ornamentation more accentuated, with radial grooves. Ameghino has described three species as follows: P. impressus, sculpture little accentuated, post. piliferic pits rudimentary. P. planus, sculpture more accentuated, post. piliferic pits lacking. P. tenuissimus, very small.