124 EDWARD L. RICE 
The large fenestra basicranialis posterior (fig. 2, fen.b-c.p.) 
commences immediately behind the crista sellaris, and, in the 
form of an isosceles triangle with backward pointing apex and 
rounded basal angles, extends back for more than a third of the 
length of the basal plate. By this fenestra the basal plate is 
divided in its forward portion into right and left moieties cor- 
responding to the parachordal cartilages of the lower vertebrates. 
This division is also suggested for some distance further to the 
posterior by a shallow but distinct ventral groove; but in the 
posterior portion there is no suggestion of a double origin of 
the basal plate, either in stage 5 or in any earlier stage. 
The basicranial fenestra appears to be of very general distri- 
bution in the Reptilia. Gaupp (’05 b) has collected records of 
its occurrence in Sphenodon, lizards, snakes, and turtles, and this 
is confirmed in more recent papers for Vipera (Peyer, 712) and 
Emys (Kunkel, ’712b). The advanced age of the embryos of 
Dermochelys, Chelonia, and Chelydra studied by Nick (’12) 
probably accounts for the absence of this fenestra. In the 
Crocodilia (Parker, ’83; Shiino, ’14) there is no evidence for its 
occurrence. Shiio describes an elongated perforation of the 
basal plate in connection with the forward part of the noto- 
chord, but interprets this as due to secondary resorption and 
not homologous with the fenestra basicranialis posterior. 
Gaupp describes the basal plate as octagonal in Lacerta; in 
Eumeces the form is much less regular, owing largely to the in- 
fringement of the much larger cochlear portion of the otic cap- 
sule (figs. 2 and 8, prom.coch.). In its anterior portion, from 
about the level of the posterior border of the fenestra basicran- 
ialis posterior, there is a striking lateral expansion of the basal 
plate, which practically surrounds the cochlear capsule and 
fuses with its medioventral, anterior, and laterodorsal borders. 
Except for the interruption of the facialis foramen (figs. 7 and 8, 
f.N.VII.), this fusion is continuous from the fissura metotica 
(fig. 7, jfis.m-ot.) to the prominentia recessus utriculi (fig. 7, 
prom.r.ut.), with which it is also united. In front of the otic 
capsule the free lateral margin of the basal plate is rolled out- 
ward, but not noticeably thickened (figs. 2 and 19). The edge 
