128 EDWARD L. RICE 
In stage 5 the notochord must be interpreted as already in 
degeneration—a process which is much more conspicuous in 
stage 6, where the anterior portion of the notochord is broken 
into a series of isolated fragments. A similar fragmentation is 
described by Gaupp (08a) in Echidna. In stage 6 the noto- 
chord terminates much more posteriorly than in stage 5, while 
in the earlier embryos, stages 1 to 4, the anterior end is deeply 
embedded in the cartilage of the crista sellaris. In Sphenodon 
(Schauinsland, ’00), Emys (Kunkel, 712 b), Alligator (Parker, 
’83), and Crocodilus (Shiino, 14) the notochord is described as 
penetrating the crista sellaris in certain stages and extending 
into the fenestra hypophyseos. These data practically demon- 
strate the homology of the crista sellaris of the reptiles and the 
anterior thickened margin of the basal plate, ‘Sattellehne,’ in 
the Selachii, questioned by Gaupp (’05 b) because of the more 
posterior termination of the notochord in Lactera. It is inter- 
esting to note that Gaupp himself pointed the way to the solution 
of his question when he suggested (p. 759) 
dass die Frage berechtigt ist, ob nicht vielleicht die Lage der Crista 
vor der Chorda lediglich auf friihzeitigen Schwund des vordersten 
Chordaabsehnittes zuriickzufiihren ist. Um das zu unterscheiden, 
miisste das Verhalten der Chorda von friithesten Stadien an bis zur 
Bildung der Crista sellaris verfolgt werden. 
In the earlier stages of Eumeces the posterior cartilaginous 
covering of the notochord is much more marked, while in stage 6 
the position of the notochord is more superficial with reference 
to the basal plate, and no cartilaginous investment can be cer- 
tainly demonstrated in front of the dens epistrophei. The 
dorsal covering of the notochord is not noted by Gaupp in La- 
certa, but may have been present in earlier stages. In Tropi- 
donotus (Gaupp, ’00) and Vipera (Peyer, 712) the notochord is 
wholly dorsal to the basal plate, as in Lacerta; in Sphenodon 
(Schauinsland, ’00) and in late embryos and adults of Dermoch- 
elys, Chelone midas, and Chelydra (Nick, 712) the course is 
like that in earlier Eumeces embryos, except that the notochord 
is embedded in the cartilage for a much greater part of its course. 
