234 TEETIAEY VEETEBEATA OF THE EAYtTM. 



large postero-external cusp. The talon is o£ moderate size, and its outer border is high 

 and forms a cutting-edge; it is separated from the much lower inner border by a 

 slightly concave surface, which is homologous with the basin-shaped depression of the 

 talon in the other species. On the antero-external angle of the tooth there is a well- 

 marked tubercle (stylid) belonging to the cingulum, which is wanting round the rest 

 of the crown. 



The dimensions of this specimen are : — Length, so fur as preserved, 4"6 cm. ; depth 

 of ramus beneath m. 3, 1'6 cm. The lengths of the teeth are: — pm. i, 8 mm. ; 

 m. 1, 6"5 mm. ; m. 2, 8'5 mm. ; m. 3, 11 mm. 



M. 9260. Plaster cast of the above specimen. Made in the British Museum. 



Order GET ACE A. 



Suborder ABCH^OCETI. 



Family ZEUGLODONTIDJi:. 



Facial region of skull greatly elongated ; external nares opening comparatively far 

 forwards ; nasal canal prolonged backwards by the union of the maxillae, palatines, and 

 pterygoids, so that the internal nares are far back ; nasal bones elongated ; frontals 

 forming broad supraorbital processes. Parietal region of the skull very narrow, and 

 temporal fossae very large. In the earliest forms (^Protocetus) the normal eutherian 

 dentition seems to have been present, and the teeth behind the second premolar 

 have three roots. In the later forms (Zeuglodon) the dentition is reduced, probably 

 by loss at the hinder end of the series ; the anterior premolars may have one or 

 two roots, but the other teeth of the molar-premolar series are two-rooted, and have 

 compressed crowns with sharp serrated edges. The new genus Prozeuglodon described 

 below is intermediate between these two types. 



The Zeuglodonts of the Fayum are especially interesting, because the first 

 mammalian bones described from this region were parts of the skeleton of a member 

 of this family. In 1879 Schweinfurth collected some vertebrae, including an axis, 

 from the island Geziret-el-Qorn in the lake Birket-el-Qurun : the beds in which 

 these remains were found belong to the Birket-el-Qurun series of Beadnell, forming 

 the upper part of the Lower Mokattam beds. The specimens were described by 

 Dames *, by whom they were referred to three forms : — (1) a large species with 



* Sitzungsb. k. preuss. Aiad. "Wiss. vol. i. (1883) p. 129. 



