R. S. Lull — New Tertiary Artio dactyls. 93 



Facial and cranial bones. — There is no trace of a subor- 

 bital or lachrymal fossa as in most of the deer and 

 antelopes, and herein again Aletomeryx agrees with Anti- 

 locapra and with the Bovidse. 



In the present genus, as well as in Blastomeryx, Dromo- 

 meryx, and Antilocapra, there is on either side of the 

 face a fontanelle closed during life by membrane but now 

 opening into the nasal cavity. This is bounded by the 

 frontal, lachrymal, nasal and maxillary bones. Supra- 

 orbital foramina through the frontal into the orbits are 

 also present in each genus. These in Antilocapra may be 

 single or divided by a bar of bone into two spaces varying 

 in proportions. In the female Aletomeryx skull No. 10747, 

 there are three such foramina arranged in an oblique 

 row on either side of the median line of the skull, while 

 in skull No. 10744 (sex indeterminate), there are but 

 two ; again in a third female, No. 10735, one only is 

 present, which is also true apparently of male skull 10734. 

 There is, as in Antilocapra, a distinct groove (sulcus 

 supraorbitalis) running from this supraorbital foramen 

 to the fontanelle already mentioned. This is least dis- 

 tinct in No. 10748, where there are three foramina instead 

 of one. This groove marks the course of the frontal 

 vein. (See fi.g. 4 A, B.) 



Just without the supraorbital groove, a little behind 

 the anterior limit of the orbit, is a distinct protuberance 

 which has no equivalent in Antilocapra nor in Bromo- 

 meryx. The fronto-lachrymal suture passes through this 

 eminence, which seems almost like an incipient horn. It 

 is present, though varying in development, in both male 

 and female skulls. 



Lachrymal foramina are double as in Antilocapra, and 

 lie just within the limits of the orbit, although the anterior 

 one is almost on the margin. "In most deer the orifice 

 of the lachrymal canal is double and situated on the mar- 

 gin of the orbit, whereas in most of the hollow-horned 

 ruminants it is single and placed well within the mar- 

 gin. There are, however, exceptions in both cases" 

 (Flower). Both Aletomeryx and Antilocapra are among 

 the exceptions. 



The frontal bones extend backward to a point a little 

 behind the orbits, much as in Antilocapra, but instead 

 of crossing the supratemporal ridge delimiting the tempo- 

 ral fossa, as in the prongbuck, the fronto-parietal suture 

 follows for the most part the very apex of the ridge 



