Die Unterfamilie der Lutrinae 



21 



Schädel. Unterkiefer. ,,This Carnivore is represented by a 

 left mandibular ramus, which contains alveoli and crowns of the 

 canine and molars, excepting those posterior to the sectorial. 

 These teeth have the formula, four premolars, of Mustela and 

 of the Dogs, but the sectorial is much more like that of Lutra, 

 than that of either of the genera named. The heel of this tooth 

 is long and encloses a Wide space transversely, while the sectorial 

 portion is short and low, and encloses a large internal tubercle. 

 In the absence of the tubercular teeth, the generic reference is 

 uncertain but the characters agreeing, so far as they go, with 

 the genus Lutrictis of Pomel [Poiamotherium Is. Geoffr.], I refer 

 it there provisionally. The first premolar only is one-rooted; the 

 third is wide behind, deVeloping a low heel. The heel of the fourth 

 is a little better developed and there is a smaU anterior basal 

 cutting lobe; there is also a tubercle on the posteror cutting edge 

 at the middle. The three corners of the anterior part of the sec- 

 torial tooth are situated at the corners of an imaginary equilateral 

 triangle. The heel continues the width of the crown, is wider 

 than long and is abruptly truncate behind. It supports a long 

 cutting edge just within the external border, and a shorter one 

 on the internal. The surface of the enamel is smooth. There 

 are two mental foramina, one below the interval between the first 

 and second premolars, the other beneath the anterior root of 

 the third premolar. 



Maße. Length of molar series without tubercular 22 mm; 

 Diameter od sectorial antero-posterior 6,6 mm; transVerse 4 mm; 

 Length of heel of sectorial 2,4 mm; Length of fourth premolar 

 4,5 mm; Elevation of fourth premolar 3,6 mm. 



Fundort. From the Loup Fork forma tion of Cottonwood 

 Creek, Oregon, discovered by Charles H. Sternberg. Mascall 

 Formation, Obermiocän. Cope [1879]. 



e) [5.] f Potamotherium lorteti (Filhol) 

 Literatur. Filhol [1883]; Schlosser [1888]; Hofmann 

 [1887; 1888]. 



Type. Im Lyoner Museum? 



Schädel. Unterkiefer. Er hat die Form wie bei Lutra. 

 Ein For. mental, zwischen P2 und P3, 4 mm unter dem Rand 

 der Alveole. Ob noch ein zweites vorhanden war, ist unbekannt. 

 Zahnformel des Unterkiefers : 13; Cl; P4; M2. Die Praemolaren 

 sind ziemlich kurz, stumpf und sehr massiv. Der erste ist ein- 

 wurzlig, mit seitlich zusammengedrückter Wurzel, die Abmes- 

 sungen seiner Alveole sind: Länge 3 mm, Breite 2,5 mm. Der 

 P2 war zweiwurzlig. Seine wenig dicke Krone fiel nach vorn 

 ziemlich steil ab, nach hinten aber schräg. Rund um den Zahn 

 läuft ein basales Cingulum. Ohne Nebenspitze. Länge 4 mm, 

 Breite 3 mm; Höhe 3 mm. Der dritte Praemolar ist ebenso, aber 

 etwas größer, mit schwacher hinterer Cingulumspitze. Länge 



9. Heft 



