404 MAMMALIA. 



skull in most forms has a more produced facial region than 

 is observed among the apes ; the lachrymal foramen nearly 

 always opens on the cheek, not within the orbital rim ; and 

 the orbit is only divided from the temporal fossa by a post- 

 orbital bar, not completely separated from it by a thin lamina 

 of bone, as is the case in the apes and man. The earliest 

 genera, so far as known, exhibit the most generalized dentition ; 

 and these animals in the Eocene period lived not only in 

 Europe but also in North America, while at the present day 

 they are exclusively confined to Madagascar, parts of Africa, 

 and the southern Asiatic region. They seem to have become 

 extinct both in Europe and in North America at the dawn of 

 the Miocene period, when apes began to appear at least in the 

 Old World. 



Anaptomorphus. A very small animal, with short and broad rounded 

 skull and enormous orbits, of lemuroid type. The dental formula is 



i. ?, c. 1, pm. 2, rn. 3 , 



r-^r i - . Ihe canine is relatively very small, and when a 



i. ^&, c. l, pni. L o, m. o 



third premolar is present in the lower jaw in front of the usual pm. 3, 4, 

 this is still more diminutive. The premolars are simpler than the molars, 

 and the lower incisors are almost or quite erect. The upper molars are 

 triangular in shape, tritubercular, and diminish in size backwards ; the 

 lower molars are quadritubercular. The mandibular rami are not fused 

 together at the symphysis. Anaptomorphus homuncuhis, with the skull 

 about O03 m. in length, occurs in the Lower Eocene (Wasatch Formation) 

 of Wyoming. Necrolemur, known by equally satisfactory remains from 

 the Upper Eocene Phosphorites of Quercy, France, seems to be an allied 

 genus ; and the jaws named Microchcerus erinaceus, from the Upper Eocene 

 of Hordwell, Hampshire, probably belong to a similar animal. 



Adapis (fig. 226). The best-known Eocene lemuroid, with a complete 

 dentition (the usual 44 teeth) in close and regular series. The cranium is 

 elongated, with a remarkably elevated sagittal crest upon the brain-case. 

 It exhibits all the characteristic features of a lemuroid, arid the rami of 

 the mandible are fused together at its symphysis. The incisors are small 

 and spatulate or chisel-shaped, those of the mandible directed a little 

 forwards. The canines are larger than the incisors. The premolars, above 

 and below, gradually increase in size backwards, pm. 1 being diminutive or 

 even rarely wanting ; the first three are simply conical, with a basal cin- 

 gulum at least on the inner side, while upper pm. 4 is tritubercular and 

 lower pm. 4 quadritubercular. The upper molars are quadrate in shape and 

 increase in size backwards ; each bears four tubercles, the two outer ones 

 pyramidal in form, the antero-inner tubercle V-shaped, and the postero- 



