CHONDROCRANIUM OF EUMECES 147 
pendent development in Sphenodon. On the other hand, Gaupp 
‘(08 a) finds conditions in Echidna in full accord with his theory. 
Terry (17) harmonizes the views of Gaupp and Noordenbos. 
Describing the otic capsule of the cat as chondrifying independ- 
ently of the main part of the basal plate, but interpreting the 
suprafacial commissure, after Gaupp, as a parietal portion of the 
basal plate, he concludes (p. 363): 
If we can, on the evidence given, interpret the suprafacial commissure 
as a parietal structure in the cat, it would appear that its relation to 
the cochlear capsule (continuity) affords support to the theory (Gaupp) 
of the latter having preempted the territory of the basal plate and 
developed at its expense. 
The evidence of Eumeces, while not conclusive, is favorable to 
Gaupp’s view, and adds one more to the series of gradations 
afforded by the Reptilia intermediate to the extreme conditions 
found in Amphibia and Mammalia. In Chelone (Gaupp, ’05 b; 
Nick, ’12) and Dermochelys (Nick, 12) the invasion has hardly 
begun and conditions are still almost as in the Amphibia; Che- 
lydra (Nick, 712) and Emys (Kunkel, 712 b) lead up to Lacerta; 
Crocodilus (Gaupp, ’05b, citing and confirming Parker, 83; 
Shiino, 714) and Eumeces show the maximum of this develop- 
ment in the reptiles. From the mammalian side the gap is 
further decreased by the observation that in Echidna (Gaupp, 
08 a) and marsupial embryos (Broom, ’09) the uncoiled cochlea 
and its relations to the basal plate are still extraordinarily rep- 
tilian. 
Foramina acustica, anterius and posterius (fig. 8, f.n.VITT.a. 
and f.n.VIII.p.). In stages 5 and 6 of Eumeces these foramina 
are essentially as in Lacerta. -As in Lacerta, the anterior fora- 
men is so overhung by a lip-shaped projection of cartilage that 
the opening itself is barely visible in median view. In earlier 
stages the cartilage between the acusticus foramina is less definite, 
and in stage 1 these and the endolymphatic foramen become 
perfectly confluent—a condition already described by several 
authors in a variety of reptiles and mammals. In no stage do 
I find any suggestion of the division of the anterior foramen into 
