CHONDROCRANIUM OF EUMECES 207 
5. Hypoglossus foramina two or three, sometimes asym- 
metrical on two sides; distinct nerve roots more numerous than 
foramina—at least five in some specimens. 
6. Course of abducens nerve (except for one asymmetrical 
individual variant with double perforation of basal plate) through 
tunnel in anterior edge of basal plate, as in Lacerta; real point 
of exit from cavum cranii not this tunnel, but fenestra metoptica. 
7. Evidence as to nature of tectum posterius inconclusive; 
tectum apparently, at least in part, of occipital origin. 
8. Cochlear portion of otic capsule greatly exaggerated in 
Eumeces as compared with Lacerta; outer contours and inner 
structure of capsule otherwise essentially similar in both forms. 
9. Facialis foramen displaced to intercapsular position, as 
consequence of exaggeration of cochlear portion of capsule, and 
‘prefacial’ commissure rendered rather ‘suprafacial’—conditions 
strikingly suggestive of Mammalia and strongly favoring Gaupp’s 
view of progressive invasion (Amphibia-Reptilia-Mammalia) of 
basal plate by cochlea. 
10. Fissura metotica less extended dorsally than in Lacerta, 
and more completely divided, by contact of posterior ampullar 
prominence and basal plate in region of anterior hypoglossus 
foramen, into recessus scalae tympani and foramen jugulare. 
11. Connective tissue of recessus scalae tympani forming more 
definite closing membrane for fenestra cochleae, especially in 
stage 6, than in Lacerta; and outer portion of this membrane, 
corresponding to filling of lateral aperture of recessus in Lacerta 
and early embryos of Eumeces, more closely homologous with 
mammalian membrana tympanica secundaria than recognized 
by Gaupp. 
12. Course of glossopharyngeus nerve in some specimens of 
Kumeces, as in Lacerta, typically ‘extracapsular’—through reces- 
sus scalae tympani; in other specimens of Eumeces ‘intracapsular’ 
—entering otic capsule through independent foramen in cartilage 
of median wall; exit in Eumeces always through connective tissue 
_of fenestra cochleae and lateral aperture of recessus rather than 
through cartilage of lateral wall as in certain reptiles. Variation 
in Eumeces not dependent upon age. Seeming contradiction 
