1 882.] Geology and Paleontology. 157 



may be therefore written. I. 2 ; C. 1 ; Pm. 3 ; M. 3 ; or I. 3 ; C. O; . 

 Pm. 3 ; M. 3 ; or I. 3 ; C. 1 ; Pm. 2 ; M. 3. The first and second 

 incisors are large and rodent-like, growing from persistent pulps ; 

 the second are the larger. The third, or canines, are small and 

 probably not gliriform. There is no diastema. The first premolar 

 (or canine) has a compressed crown with two cusps placed trans- 

 versely to the jaw axis, and has a complete enamel sheath, and 

 probably two roots. The succeeding tooth is also transverse, and 

 is two-rooted, judging from the alveolus. The first and second 

 true molars are rooted, and the crown consists of two transverse 

 separated crests, each partially divided into two tubercles. On 

 wearing, the grinding surface of each assumes the form of a let- 

 ter B with the convexities anterior. The last inferior molar is in- 

 jured. The rami are short, and the symphysis deep and recurved. 

 This genus may be named Psittacotlicrium. 



Psittacotkerium multf/ragum, sp. nov. — The base of the coronoid 

 process is opposite the junction of the second and third true 

 molars. The ramus is deep and moderately stout. The enamel 

 of the first incisor does not extend below the alveolar border, at 

 the internal and external faces, and does not reach it at the sides. 

 It has a few wrinkles on the anterior face. The anterior enamel 

 face of the second incisor is thrown into shallow longitudinal 

 grooves with more or less numerous irregularities from the low 

 dividing ridges. There is a deeper groove on each side of the 

 tooth, and there are about a dozen ridges between these on the 

 anterior face. Both cusps of the first premolar are conic, and the 

 external is the larger. The second true molar is a little smaller 

 than the first. The enamel of the premolars and molars is smooth, 



Probable length of dental series .0750 ; diameters of I. 1 : an- 

 teroposterior .or 20, transverse 0066; diameters I. 2: anteropos- 

 terior .0160, transverse .0115 ; diameters Pm. 1. : anteroposterior 

 .0072, transverse, .0130; diameters of M. 11: anteroposterior .0090, 

 transverse, .0090. Length of true molars .0038; depth of ramus 

 at M. 11. .0360. 



The short deep jaws of this animal must have given it a very 

 peculiar appearance, not unlike that of a parrot in outline. — E. D. 



A great deposit of Mud and Lava. — The Atlantic and Pacific 

 R- R. traverses the Territory of New Mexico westward from the 

 Rio Grande river, north of its center. For a great part of the 

 distance between that river and the Arizona border, it passes over 

 the plateau of the Sierra Madre, which chiefly consists in this 

 region of mesas. The mountain ranges to the north are not in 

 sight from the railroad, and those of the south are visible at a 

 distance. The plateau is a large anticlinal one hundred miles in 

 width, and consists of triassic and Jurassic beds. The - 



