CONDYLAETHEA. 415 



much resembles. The molar teeth are narrower behind, and the fourth pre- 

 molar is larger. 



From the Puerco beds of Northwestern New Mexico. Discovered by 

 D. Baldwin. 



HAPLOCONUS Cope. 



American Naturalist, 1882, p. 417 (April 25). 



1 4 3. 



Dental formula: I.?; C. -r; P-m. — ; M. -^ ; no diastemata. Canines 



well developed; superior first premolar one-rooted; third superior premolar 

 a flattened cone, without accessory crest or cusp; fourth superior premolar 

 with crown of an external cusp, and an internal crest, as in the genera just 

 preceding. Superior true molars with crowns consisting of two external 

 cusps, a median V directed inwards, and a distinct posterior internal cusp. 

 No other cusps of superior molars. Inferior premolars without internal 

 tubercle or cusp; the first one-rooted. True molars with four tubercles in 

 pairs, and a posterior median tubercle. Anterior median tubercle present 

 or absent. Third inferior true molar with a heel. Angle of mandible not 

 inflected or reflected. 



The skeleton of this genus is unknown. The true molars of the supe- 

 rior series are those of Anisonchus, but the third premolar is entirely diifer- 

 ent. Some of the species are distinguished by the absence of the anterior 

 median tubercles of the inferior true molars, while others possess it. I can- 

 not divide them into two genera on this account, as the tubercle in question 

 is sometimes very small, and in some cases indistinguishable. Besides this, 

 the species differ like those of Anisonchus, in the form of the internal 

 tubercle of the superior fourth premolar. In the one group it is a cone; in 

 the other a crest, or strong cingulum rising into a cone. This will also prob- 

 ably prove to be an evanescent character in some species not yet discov- 

 ered. An intermediate form is seen in the fourth superior premolar of the 

 Anisonchus coniferus; and the two forms are displayed in a less typical con- 

 dition in the two species of Protogonia. 



The four species are all known from their mandibular rami, and the 



