SINCLAIR: MARSUPIALIA OF THE SANTA CRUZ BEDS. 425 



PAL^.O THENTIN^E. 

 PAL^EOTHENTES (Moreno) Ameghino. 



(Plates LXIII, Figs. 1-7; LXIV, Figs. 1-2 ; Text Fig. 8.) 



Palceotenthes Moreno; Patagonia, Resto de un Continente hoy sub- 



mergido, p. 22, 1882 (nomen nudum). 

 Palteotkenfes (Moreno) Amegh.; Enum. Sist. Especies Mamif. F6s. Pat. 



Aust, p. 5, 1887. 

 Palceotheutes Lydekker; Zool. Record for 1887, XXIV, Mamm., 54, 



1888. 

 Epanorthm Amegh.; Contrib. al Conoc. Mamif. F6s. Rep. Argent., pp. 



271-272, 1889. 



Metaepanorthus Amegh.; fenum. Syn., p. 92, 1894. 

 Paraepanorthiis Amegh.; 6num. Syn., pp. 93-94, 1894. 



This is the most abundant and best known of the Santa Cruz diproto- 

 donts, at least four species being represented in the collections at Prince- 

 ton University and the American Museum of Natural History. 



Dentition (Pis. LXIII, figs. 1-7; LXIV, figs. 1-2). --The dental for- 

 mula in Palceothentes is ], j. Three upper incisors are figured by Ame- 

 ghino (1895, P- 9 6 > % 7 6 ; 1903. P- MI. fig- 62, p. 170, fig. 95) for P. 

 minntus. The premaxillary region has been broken from the only skull 

 in the Princeton collection (No. 15,225) and the incisor formula cannot be 

 verified. The canine has also been broken in this specimen. From the 

 cfoss-section of the root it appears to have been considerably flattened 

 laterally. The premolar-molar series forms a crescent, tapering in width 

 at both ends, with the convexity directed outward. The three upper pre- 

 molars may be either closely crowded (P. intermeditts, PI. LXIV, fig. i) 

 or moderately spaced (P. aratce, PI. LXIII, fig. 2a). The anterior pre- 

 molar is single-rooted in the latter species, double-rooted in P. intenne- 

 ditts. The tooth has been shed in the only specimen of P. aratce in the 

 collection (No. 9549, Am. Museum) and in the skull of P. intermedia* 

 has been considerably damaged. The median premolar is laterally com- 

 pressed, with a central cusp and well marked anterior and posterior acces- 

 sory cuspules. The posterior premolar is a smooth trenchant blade, 

 greatly widened posteriorly and tapering to an edge in front, where a 



