PA )M A S'1’0 DON AVI NT( )N[ . 
157 
incisors arc wanting but which is othcn-wise nearly complete (text-fig. 54), may be 
regarded as a co-type. 
'I'his species differs from P. headnelli in (1) its somewhat smaller size; (2) the 
extension backwards of the symphysis so that its posterior border is only just in front 
of pm. 3 ; (3) the position of the mental foramen on the side of the symphysis instead 
of behind it ; (4) the greater complication of the molars and their greater length in 
proportion to the width, the last lower molar (text-fig. 50 B) consisting of three 
transverse crests and a distinct talon. From P. minor and P. parims this species is 
easily distinguished by its larger size and the difference of its last lower molar (see 
text-fig. 50). 
P. ivintoni seems to be by far the commonest species, and probably the greater 
number of specimens above referred provisionally to P. headnelli belong here. This 
Text-fig. 53. 
Mandible of Pcilceomastodon wintoni, type specimen, from abo\ e. 
cond., condyle; cor., coronoid process ; d.c., dental canal ; incisoi’. The premolars and first molar 
on the left side have been restored from another specimen, i nat. size. 
remark particularly applies to the skulls and upper teeth, which, in the absence of 
associated skulls and mandibles, cannot be determined with certainty ; though the 
absence of any mandibles of the type of P. headnelli from the pits in which most 
of these specimens were collected is strong presumptive evidence that they do not 
belong to that species, but to the present one, to which all or nearly all the mandibles 
and lower teeth are referable. 
Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. 
M. 8414. Mandible wanting the angular region and the cheek-teeth in front of m. 2. Type 
specimen figured (text-figs. 50 B, 53). The incisors are preserved ; they are procumbent 
and spatulate teeth terminating in a point ; their width at the base is 5’2 cm., the length 
