228 G. W. BARTELMEZ 
work has been done on the early development of the nervous 
system in these forms. The only complete study is the Nor- 
mentafel of Minot and Taylor (05) for the rabbit. In the first 
embryo of their series they noted the broad expansion of the 
neural folds rostrally and suggested that this might be the first 
indication of the optic anlage. This specimen had five somites. 
Since the eight-somite embryo (no. 4) had well-developed vesi- 
cles, it is probable that there were optic anlagen in the cephalic 
plate of the former. The thickening for the otic plate as well 
as the ‘acoustico-facial ganglion’ and the trigeminal ganglion 
were recognized in the nine-somite specimen of table 5. 
Keibel, in 1889, figured the optic primordia of a guinea-pig 
embryo 16 days, 7 hours, old in sagittal section (fig. 44 and 45) 
and Foriep (’05, p. 157) has reproduced a photograph of a trans- 
verse section from a 3-mm. embryo. In both instances there is 
a deep broad pit situated laterally in the neural fold. Bischoff’s 
monograph on the guinea-pig furnishes no data on this subject. 
I nsectivores 
For the mole we have concrete data in the classic monograph 
of Heape (’87). He recognized the optic grooves in an embryo 
of three somites (stage E) where they are as well developed as 
in our eleven-somite H392 (fig. 9d). Heape calls attention to 
the very early appearance and typical form of the optic primordia 
in this form where the eye is subsequently degenerate. The 
otic plate is referred to in stage J when the optic vesicles are 
well developed and the neural folds are closed as far forward as 
the cranial flexure. His figure 25 is from a section of a fourteen- 
somite embryo in stage H and shows a slightly thickened otic 
plate. 
Primates 
Our knowledge concerning the pertinent stages of primates 
other than man is due entirely to Selenka and Huprecht. 
Selenka (’91, ’00) obtained three embryos from the period we 
are considering. His figure of the Hylobates embryo ‘Ab’ (’00, 
