130 TBETIAET VEETEBEATA OF THE EATtTM. 



Family PALiEOMASTODONTIDiE. 



In the skull the nasals shortened and the external nares somewhat shifted back 

 from the end of the snout. Mandible with elongated spout-like symphysis, projecting 

 beyond the skull. A single pair of large incisors (^. 2) in both upper and lower jaws. 

 Upper incisors in form of downwardly-directed tusks, with a band of enamel on their 

 outer side ; lower incisors procumbent and continuing forwards the upper surface of 

 the spout-like symphysis. Premolars replacing milk-molars in both upper and lower 

 jaws ; molars with not less than three transverse ridges. 



This family includes the Eocene genus Palceomastodon and the Miocene Tetrabelodon, 

 possibly also the problematical Phiomia. The species range in size from little larger 

 than Moeritherium. to nearly as large as the existing Indian Elephant. 



Genus PAL.ffiOMASTODON, Andrews. 



[Tageblatt des V. Internationalen Zoologen-Congresses, No. 6, p. 4^ Berlin, 1901 

 (Verhandlungen, p. 528, 1902).] 



Skull with sagittal crest ; nares just in front of orbit. Dental formula : — 

 ^. J ; c. Q- ; pm- -^'t i^- -g- Last premolar bilophodont ; molars trilophodont. Neck 

 more elongated than in Elephas ; limb-bones, so far as known, much like those of the 

 later Proboscidea. 



This genus is at present known only from the Upper Eocene Fluvio-marine beds of 

 the Faytim, where it is represented by several species, the type being Palceomastodon 

 beadnelli. The several species are distinguished by (1) difference of size ; (2) the 

 form of the symphysis and its position with regard to the anterior premolars ; (3) the 

 degree of development in the last lower molar; (4) the degree of development of 

 secondary tubercles in the molars. 



The Skull (Ph. XII., XIII. ; text-figs. 48, 49 A).— Though differing widely in general 

 appearance and in many details from that of the later Elephants, the skull is 

 nevertheless typically Proboscidean in all essential points of structure, and may be 

 described in short as that of a very dolichocephalic Elephant. Some of the more 



obvious differences between it and the skull of iJ^e^'^** ^'^^ • — 0-) ^^^ relatively small 

 though still considerable development of the bone cells and sinuses in the upper 

 and hinder region of the cranium ; (2) in correlation with the last character the 

 presence of a sagittal crest, which extends to a point about over the middle of the 

 temporal fossa, where it divides into two supratemporal ridges, which run forwards 

 and outwards and probably terminated in the postorbital processes of the frontal; 

 (3) the elongation of the basis cranii and' particularly also of the palatal region, 



