18S1.] ^^^ [Cope. 



jaw ; and each, one consists of a larger external, and smaller internal cusp. 

 The true molars are also wider than long, and support two external and 

 only one internal cusps. 



The orbits are large and are entirely enclosed behind. The frontal bone 

 does not send inwards to the alisphenoid a lamina to separate the orbit 

 from the temporal fossa, as is seen in Tarsius. There is no sagittal crest, 

 but the temporal ridges are distinct. The occipital region protrudes beyond 

 the foramen magnum, or at least beyond the paroccipital process, which is 

 preserved, the condyles being lost. The otic bulla is large, exi ending 

 anteriorly to the glenoid cavity. The pterygoid fossa is large, the external 

 pterygoid ala being well developed, and extending well upon the extero- 

 anterior side of the bulla, as in Tarsius. As in that genus, the foramen 

 ovale is situated on the external side of the bulla, just above the base of 

 the external pterygoid ala. The carotid foramen, as I suppose it to be, is 

 situated at the apex of the bulla. The lachrymal foramen is situated 

 anterior to, and outside of the orbit as in Lemuridce generally. 



The cast of the anterior part of the left cerebral hemisphere is exposed. 

 This projects as far anteriorly as the middle of the orbits, leaving but 

 little room for the olfactory lobes. The relations of the latter as well as 

 of other parts of the brain will be examined at a future time. The part 

 exposed does not display fissures, and gentle undulations represent con- 

 volutions. 



The characters of this genus now known, warrant us in thinking it one 

 of the most interesting of Eocene Mammalia. Two special characters 

 confirm the reference to the Lemuridce which its physiognomy suggests. 

 These are, the external position of the lachrymal foramen, and the un- 

 ossified symphysis mandibuli. Among Leimiridw, its dental formula agrees 

 only with the Indrisince, which have, like Anaptomorphus, two premolars 

 in each jaw. But no known Lemuridoi possess interior lobes and cusps of 

 all the premolars, so that in this respect, as in the number of its teeth, 

 this genus resembles the higher monkeys, the SiiniidcB and Rominidm,* 

 more than any existing member of the family. Of these two groups the 

 resemblance is to the Ilominida in the small size of the canine teeth. It 

 has, however, a number of resemblances to Tarsius which is perhaps its 

 nearest ally among the lemurs, although that genus has three premolars. 

 One of these points is the anterior extension of the otic bullae, which is 

 extensively overrun by the external pterygoid ala. A consequence of 

 this arrangement is the external position of the foramen ovale, just as is 

 seen in Tarsius. Another point is the probably inferior position of the . 

 foramen ovale. Though this part is broken away in the cranium of Anapto- 

 morphus homunculus, the paroccipital process is preserved, and has the 



* In an early description oi Anaptomorphus, Proc. Amer. Pliilos. Soc, 1873, the 

 types make me say " this genus * * might be referred decidedly to the Le- 

 muridce, were it not for the unossifled symphysis." It is scarcely necessary to 

 state that Simiidoe should be read in place of Lemuridce. 



