CONDYLARTHRA. 425 



the cingula. Between it and the internal side of the base of the external 

 cusp is a rudiment of the anterior intermediate tubercle. No posterior 

 intermediate tubercle. The external face of the external lobe of the crown 

 is flat. The anterior and posterior cingula terminate externally at the an- 

 gles of the crown, the anterior rising into a prominent angle. Internally 

 they extend to near the internal border of the crown, but do not pass round 

 it The external cusps of the true molars are conical, as are the smaller 

 intermediate tubercles. The anterior internal tubercle is the apex of a V, 

 and is larger than the posterior internal. The latter is well developed, and 

 is a cone. A distinct cingulum extends round the crowns except on the 

 inner side. It rises to an angle at the anterior external corner of the crown. 

 The first and second inferior true molars support six cusps, three pos- 

 terior and three anterior. The three posterior are arranged round the pos- 

 terior raised edge of the crown. The three anterior are two internal and 

 one external. The last is the largest, and the anterior internal is the 

 smallest, and is close to the posterior internal. The latter is a little behind 

 opposite to the anterior external, and is connected with the posterior 

 external by a low oblique ridge, thus completing a V- The three anterior 

 tubercles are connected by ridges, and form on wearing, a narrow trans- 

 verse U' No cingula. The fourth inferior premolar has a short, wide heel, 

 with reverted edge and a large principal cusp. On the inner posterior side 

 of the latter is the internal cusp, closely connected ; and at the anterior base 

 is a prominent tubercle, inside the longitudinal axis of the principal cusp. 

 No cingula. Last true molar unknown. 



Measuremeyits. 



M. 



Length of superior P-m. iv with M.'s i and ii 0215 



< anteroposterior 0060 



Diameters p.m. iv 5 t^^^^^^jgg O^.g 



P-ni. iv I 

 Diameters of M 



< anteroiiosterior 007 



■ " { transverse , 0095 



Length of inferior P-m. iv, with M.'s i and ii 023 



„. . o • S iiuteroposterior 007 



Diameters P-m. IV ^ ' 



( transverse 0046 



S anteroposterior 0075 



Diameters of M. i ^ ^^.^^g^^^^g g^g 



Puerco formation of New Mexico, discovered by D. Baldwin. 



