170 
TEKTlAliY VEllTEBllATA OF THE FATtjM. 
Plliomia serridens, Andrews Sc Beadnell. 
[Plate XVIII. figs. 4, 4 a.] 
1002. Phiomia serridens, Andrews & Beadnell, A Preliminary Note on some new Mammals from 
the Uj)per Eocene of Egypt, p[). 1-5, figs. 1, 2 (Survey Dept., Cairo). 
1005. PaUromaslodon, juv., Sclilosser, Neues Jalirb. £. Mineralogie, etc. vol. i. pt. i. (Referate) 
p. 157. 
Type Sj^echnen . — Anterior portion of left ramns of mandible Avith incisor and two 
cheek-teeth, figured and described loc. cit. siqjra, also PI. XVIII. figs. 4, 4 a,* 
Geological Museum, Cairo. 
The type and only known species, with mandibular symphysis 6*5 cm. in length. 
Form. & Loc. — Fluvio-marine beds (Upper Eocene): north of Birket-el-Qurun. 
The mandibular ramus (PI. XVIII. figs. 4, 4 a) upon which the species is founded is 
incomplete posteriorly. The symphysial region {sym.) is very long and deepens consider- 
ably from before backwards ; the upper surface Avith its felloAvof the opposite side must 
have formed a spout-like groove, Avhile the ventral surface is strongly convex from side 
to side and to some extent also from before baclcAA'ards. Behind the symphysis the 
ramus of the jaAv arches outAvards, its outer surface being convex from before back- 
wards and also from above doAviiAvards ; the inner surface is concave in the former 
direction and neatly flat in the latter. There are tAvo foramina on the outer face ; 
one, the larger of the tAvo, is just behind the socket of the incisor; the other is beneath 
the anterior end of the second of the cheek-teeth in situ. The bone shoAvs traces of 
the peculiar fibrous appearance characteristic of many young bones, a circumstance 
Avhich tends to support Schlosser’s vieAv as to the nature of the specimen. 
The incisor (i. I) is of very peculiar form. Its inner border, Avhere it is in contact 
Avith its felloAv of the opposite side, is straight. The outer edge is convex in front and 
is marked by a series of crenulations (about five in number). The upper face of the 
tooth is concave from side to side, the ventral convex Avith tAvo or three slight 
longitudinal ridges. The tooth thickens rapidly toAvards its base. The enamel 
covering is confined to the end of the croAvn ; it is found on both the upper ami 
lower suifacc ; on the outer side it extends back as far as the last of the denticulations, 
and on the inner not quite so far. The incisors must have formed a spout-like 
continuation of the symphysis, much as in Falcvomastodon. The great size and increase 
in thickness of these teeth towards their base make it difficult to regard them as 
belonging to the milk-series ; on the other hand, if they are the permanent incisors, 
they could never have attained the size of those of PaUvomastodon beadnelli or 
wintoni, so that if this animal Avas a Paleeomastodun it must have been quite a small 
species. 
