COPE. J PALEONTOLOGY — MIOCENE PERIOD. 471 



with that in Ictops. Such peculiarities are generally regarded as tangi- 

 ble definitions of generic groups, and are such in this case, although 

 they separate species which have considerable resemblance in some other 

 respects as far as known. 



The molars of the superior series have two exterior compressed conic 

 cusps and a stout subtriangular internal one. Behind the latter is a 

 strong cingulum, supporting a rudimental cusp behind and within the 

 principal one. Interiorly, there are three tubercular molars, of which 

 the two anterior are composed of two elevated cross-crests, which form 

 partial Y's, opening to the inner side. The sectorial supports three an- 

 terior conic tubercles, the inner and outer equal, and a heel with a conic 

 tubercle on the outer side. The number and character of the teeth in 

 front of this one are unknown. 



Portions of the cranium jDreserved present general characters of Lep- 

 tictis. There is a strong postglenoid process giving support to a thin 

 zygomatic process. Behind the base of the latter, the squamosal is 

 pierced by three large foramina, the inferior bounded by a ridge above 

 and one below. . The mastoid and paramastoid ])rocesses are rudimental, 

 and the occiput is transverse and bounded by a well-marked inion. 

 The petrous bone is large, and there is space for a large bulla, but its 

 existence is uncertain. There is a longitudinal crest directed forward 

 and inward in advance of the postglenoid process, which is probably 

 in line with the external pterygoid ala. 



The cervical vertehrm are short and transverse, and have well-developed 

 laterial arterial foramina and diapophyses. The centra are depressed 

 to a cousiderable degree, and are without hypapophyses. The neural 

 arches are narrow, and without spines. The atlas is expanded, and has 

 a very short diapophysis. The axis has a solid obtuse processus odon- 

 toideus. The dorsal vertebrae are smaller than the cervical in transverse 

 diameter of the centrum, which somewhat exceeds the length ; the articu- 

 lar faces are nearly plane. The intervertebral foramina arequite large, and 

 the narrow neurapophysis is almost entirely occupied by the basis of 

 the diapophyses. These are well developed, obliquely truncate below 

 at the end, and grooved on the under side of the shaft. The neural 

 spines are elevated, narrow, and acute in front. The ribs are flat, and 

 the capitular and articular faces are well developed. 



The prcesternwn is shaped somewhat like the sternum of a bird. It 

 has a prominent inferior longitudinal keel, which disappears posteriorly, 

 leaving a vertically oval lace of articulation for the second sternal seg- 

 ment. The superior face is slightly concave, and the only lateral artic- 

 ular faces are those for the attachment of clavicles, and are of consider- 

 able size. The borders of the bone are but little contracted behind 

 them. The scapula is elongate, and has an elevated crest, descending ab- 

 ruptly near the glenoid cavity. Thelatter is an elongate oval, the border 

 at one end more produced than at the other, and terminating in a short 

 hooked coracoid. 



The humerus has a protuberant head and shaft, and condyles much 

 flattened. The head is nearly 180° in arc, is i)Osteriorly directed, and 

 of compressed form. On the inner side is a depressed tuberosity for 

 the pectoralis muscle, while opposite to it the large deltoid crest rises 

 as high as the head parallel to it. Distally, the condyles are continuous, 

 nearly concave, and supplemented by a huge inner and a smaller outer 

 tuberosity. There is no supracondyloid foramen, but a strong arterial 

 foramen. 



The cast of almost the entire brain is preserved, and, as the parietal 

 bones are wanting, the proportions are clearly traceable. The olfactory 



