CHONDROCRANIUM OF EUMECES 209 
19. Development and relations of processus basipterygoideus 
essentially as in Lacerta, and consistent with Gaupp’s interpre- 
tation as homologue, wholly or in part, of mammalian alisphenoid. 
20. Lateral wall of temporal region in no single stage of Eu- 
meces so complete as in Gaupp’s figures of Lacerta, but all ele- 
ments and fenestrae of latter recognizable in composite of early 
and late stages of Eumeces. Most cartilages of this region in 
marked retrogression in stage 5, but taenia marginalis in progres- 
sion, and just effecting union with otic capsule and solum supra- 
septale. Fenestra prootica subdivided, in early embryos of 
Eumeces, by additional cartilage elements not noted in Lacerta. 
21. Solum supraseptale clearly a paired structure, its two 
halves uniting with septum rather than with one another. 
22. Ethmoid cartilages relatively late in their development. 
23. Septum nasale dorsally exposed in middle of double 
fenestra olfactoria, between extraordinarily large fenestrae su- 
periores nasi, and, possibly, between foramina apicalia. Ventral 
edge of septum considerably thickened, and another less marked 
thickening in middle height, associated with os septomaxillare. 
No prenasal extension of septum. 
24. Progressive fenestration of septum nasale similar to that 
of septum interorbitale. 
25. Foramina apicalia and foramina epiphanialia, as in Lacerta, 
serving for exit, respectively, of internal and external branches 
of ethmoid ramus of trigeminal nerves. 
26. Concha and extraconchal portion of nasal capsule as in 
Lacerta except for absence, in all stages studied, of fenestra 
lateralis nasi. Interpretation of latter not clear—perhaps mere 
area of retarded chondrification, perhaps precocious develop- 
ment in Lacerta and to be sought in later stages of Eumeces 
than those available. 
27. Lateral nasal gland not mechanical cause of conchal in- 
folding, but secondarily associated with it in later stages. 
28. Superior and inferior alar processes as in Lacerta, but 
less conspicuous. 
29. Anterior maxillary process insignificant, posterior highly 
developed, extending across from os maxillare to os palatinum. 
