CHONDROCRANIUM OF EUMECES ier 
odon; on the other hand, Gaupp considers that the tectum is 
partly occipital in Tropidonotus—a view confirmed by Peyer 
(12) for Vipera. In Lacerta, Gaupp (’00) assigns a mainly otic 
character to the tectum, although not explicitly denying the 
participation of the occipital region in its formation. 
Two suggestions have been advanced concerning the tectum 
of the Mammalia, where somewhat similar confusion is in evi- 
dence, either of which may contribute also to the solution of the 
problem for the Reptilia. First, Bolk (’03) holds for Homo, 
and Noordenbos (’05) for Talpa, Lepus, Sus, and Bos that the 
tectum posterius first develops as an independent cartilage and 
only secondarily fuses with neighboring parts. A similar inde- 
pendent origin has been pointed out among the Amphibia in 
Rana and Triton by Gaupp (’93) and in Necturus by Platt (’97). 
An independent origin has been suggested as a possibility in 
Sphenodon by Schauinsland (00), but I know of no definite 
record of this phenomenon in any reptile. Second, Kernan (’16), 
on the basis of his own work and that of Macklin (’14) on human 
embryos, holds that two distinct structures have been confused— 
a more anterior ‘tectum synoticum’ and a more posterior 
‘tectum posterius.’ The former is more primitive and of earlier 
ontogenetic appearance; it is already degenerating as the latter 
is developing, thus leading to a gradual shifting of the position 
of the tectum toward the posterior, accompanied by an also 
gradual change in its character. A similar view is expressed by 
Terry (17), who homologizes the tectum of the lizard with the 
anterior element. These suggestions deserve careful review in 
connection with the reptile skull, and may help toward a satisfac- 
tory general interpretation of the tectum posterius. As yet this 
is Impossible. 
No new light is shed by my Eumeces material upon the vexed 
question of the vertebral composition of the occipital region. 
The cartilages give no visible evidence of such segmentation 
beyond the presence of the hypoglossus foramina; the irregu- 
larities in the number of these foramina have been discussed in 
connection with the basal plate. 
