. The Deseado formation of Patagonia . e posterior lobe, convert-ing bay 3 into a pit. On the posteriormargin of the tooth, the cingulum is de-veloped so as to appear like a third crista,wi^^nciVor^l&ari which iucloscd bay 4, and when the tooth —1/2 natural size. • 11 • ■, is worn, bay 4 becomes a pit my lower jaw incisor 3 is developed into a strongcaniniform tush. Most of the teeth are lacking, butlower molar 2 is a strongly compressed, hypsodont tooth,surrounded by a thick layer of enamel. This tooth rises22 mm. above the well-developed roots, and is alreadyconsiderably worn down. T
. The Deseado formation of Patagonia . e posterior lobe, convert-ing bay 3 into a pit. On the posteriormargin of the tooth, the cingulum is de-veloped so as to appear like a third crista,wi^^nciVor^l&ari which iucloscd bay 4, and when the tooth —1/2 natural size. • 11 • ■, is worn, bay 4 becomes a pit my lower jaw incisor 3 is developed into a strongcaniniform tush. Most of the teeth are lacking, butlower molar 2 is a strongly compressed, hypsodont tooth,surrounded by a thick layer of enamel. This tooth rises22 mm. above the well-developed roots, and is alreadyconsiderably worn down. The pillar is prominent as astrong fold in the middle of the posterior crescent. Inthis specimen there is no trace of the usual pit (3) indi-cative of the septum, but I should expect to find it in ayounger specimen. The mandible broadens in front into ascoop-like anterior end, and the alveoli of the first two in-cisors would indicate that they were proclivous. The alve-oli for the other teeth are aranged as in PRONESODON 125 Measurements Skull, width across the zygomatic arches 148 mm. Skull, width across opposite m. 3 (outside) 73 mm. Upper dentition, molar 2, length 25 mm., width 13 mm. Ipper dentition, molar 3, length 2t, mm., width 12 mm. Lower dentition, incisor 3, length 13 mm., width 7 mm. Lower dentition, molar 2, length 20 mm., width 7I mm. Proadinotherium angustidens Ameghino P. angustidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 467. This is based on a single lower tooth, which is consideredeither pm. 4 or m. 1, and measures 13 mm. long by 4^ Pronesodon Ameghino Pronesodon Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 626. The genus is said to resemble Proadinotherium, but withthe caniniform incisors proportionally much shorter. Anassociated calcaneimi is shorter than that of Adinotheriumand longer than that of Nesodon. Two species are described. Pronesodon cristatus Ameghino P. cristatus Amegh., 1895, Bol. Inst. Geog. Argen
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