292 TEETIAET VEETEBEATA OE THE FATtM. 



In this species the anterior lobe of the plastron is longer compared with the 

 posterior lobe than in P. antiqua, and the outline of the shell is more regularly oval 

 than in that species. Its probable identity with P. hlanckenhorni, Eeinach, is referred 

 to below. In P. (xgyptiaca from the Lower Miocene of Mogara, the lobes of the 

 plastron are longer in proportion to their width and the form of the vertebral shields 

 is different. 



Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. 



Eemains of small Podocnemid tortoises are fairly numerous in the Upper Eocene 

 beds, the anterior part of the plastron, for some reason or other, being most commonly 

 found. One of these was made the type of the present species Podocnemis fajumensis, 

 while others have been described by Eeinach under the names P. hlanckenhorni and 

 P. hlanckenhorni var. ovata, the chief differences between the two species lying in 

 the form of the suture between the epiplastrals and hyoplastrals and of the groove 



Anterior portion of plastron of Podocnemis fajumensis (type specimen). 



Ent., entoplastral bone; Ep., epiplastral bone; g., gular shield ; By.j)., hyoplastral bone; i.g., intergalar 



shield ; Ms.p., mesoplastral bone ; n., humeral shield ; p., pectoral shield. 3 nat. size. 



(From the Ann. & Mag. Nat. Hist. [7] vol. xi.) 



between the humeral and pectoral shields. Several other specimens have been 

 examined, and it is found that a considerable degree of individual variation exists 

 in this respect, so that it is not impossible that the different forms described may 

 be merely variants of one species, although further more satisfactory material will be 

 necessary to settle this point. 



In the type specimen (text-fig. 93) the anterior border is rounded, with slight notches 

 marking the boundaries of the areas covered by the epidermal shields. The anterior 

 lobe widens gently towards the bridge. The entoplastral is diamond-shaped, all the 

 sides being nearly straight. The suture between the epi- and hyoplastrals runs a little 

 backwards from the outer angle of the entoplastral, then forwards and outwards 

 parallel with the humero-pectoral groove, which is about 1-5 cm. in front of it. The 

 intergular is small, the gulars longer, meeting in the middle line for about 1 cm. 

 The humerals extend back to about the middle of the entoplastral bone (text-fig. 93). 



