RODENTS OF LIBYA 255 



sal portion of the jugals greatly expanded, forming a large portion of 

 the wide antorbital plate; maxillary component of the antorbital plate 

 narrow, owing to the extremely large size of the infraorbital foramen; 

 parietal ridge terminating in a conspicuous flattened protuberance on 

 posterior margin of the orbit; interparietal large and broadly elliptical; 

 auditory bullae heavily ossified and irregular in shape; audital portion 

 of bulla mildly inflated and meatal process heavy and projecting con- 

 spicuously laterad ; mastoidal portion of bulla moderately inflated and 

 extending posterior to occiput; portion of bulla above meatus ex- 

 panded into a rounded prominence between the mastoidal portion of 

 the bulla and the squamous portion of the temporal bone; jugular 

 processes large with distal portions directed anteromedially; basioc- 

 cipital broadly wedge-shaped and with faint median rib; pterygoid 

 processes rounded on medial aspect and hamulae applied to the styli- 

 form processes of the auditory bullae; basisphenoid present as a dis- 

 tinct rod-shaped structure between the pterygoid processes, which 

 become progressively narrower anteriorly; pterygoid fossae large, 

 partially enclosed ventrally by the palatine bones, and with large 

 foramina on their posterolateral portions; mandibular fossae large and 

 deeply grooved; upper molariform teeth with shallow kidney -shaped 

 crowns; anterior palatine foramina extremely large and bowed lat- 

 erally; upper incisors relatively small, with a decided notch distally 

 and with plain outer faces; mandible coarse and angular and with a 

 distinct medial curvature; lower molariform teeth kidney-shaped and 

 with conspicuous styles on medial surfaces; coronoid process reduced 

 to a slight elevation of the ramus; angular process small and atten- 

 uated; lower incisors small and distinctly chisel-shaped. 



Comparisons. Specimens representing Ctenodactylus gundi gundi 

 from near Rumia and Cussabat on the Gebel Nefusa, northwestern 

 Tripolitania, differ strikingly from a single to po type of Ctenodactylus 

 gundi vali from the Wadi Bey, northwest of Bu Ngem, Tripolitania, 

 in having smaller and less inflated mastoidal portions of the auditory 

 bullae, narrower rostra, larger and wider infraorbital foramina, wider 

 interorbital breadths, and heavier angular process of the mandible. 

 The skull of the specimen from Bu Ngem is badly broken, and, conse- 

 quently, most cranial measurements could not be taken. By inference, 

 however, C. g. gundi would seem to be slightly larger in most all of 

 the standard cranial measurements. Thomas (1902), in the original 

 description of Ctenodactylus vali, gives the following characters by 

 which vali differs from C. g. gundi: Auditory bullae larger; nasals 

 longer and narrower; antorbital projections more delicate; inter- 

 parietal narrower, molars smaller and more delicate (shorter antero- 

 posteriorly), and the last molar less distinctly L-shaped than in 

 C. g. gundi. In external dimensions, representatives of C. g. gundi 



