226 G. W. BARTELMEZ 
specimen (p. 10), but a fourteen-somite embryo (fig. 13) had 
well-developed optic vesicles, which indicates that the first 
anlage will be found at least as early as it isin the human. ‘Das 
Ohrgriibchen’ is first mentioned in a nineteen-somite stage. 
The Normentafeln of Sakurai (06) for the deer are more 
complete. The optic pit is first indicated in table 15 (eleven- 
somite embryo), while the otic plate appears at fourteen somites 
(table 17). 
Keibel’s first stage of the optic vesicle in the pig is a well- 
defined pit in the forebrain of a nine-somite embryo (’97, table 30). 
There is also the first hint of the otic plate here, but it must be 
remembered that the optic anlage doubtless appears earlier 
than this stage. The ten-somite series from which the Ziegler 
model was made has early optic vesicles rather than simple 
‘foveolae.’ There is a marked evagination with a relatively 
wide lumen as yet directed ventrally, not laterally. 
Carnivores 
Weigner (01) found the ‘first signs’ of an optic vesicle in 
ferret embryos 1.2 to 1.5 mm. in length in which the neural tube 
had not yet completely closed and the otic pits were already 
present. His data are not sufficiently exact to make it clear 
which primordium is actually the first to appear. In his care- 
ful study of a three-somite ferret embryo, Yeats (11) refers to 
an ‘optic prosomere,’ and it would seem from his figures that 
there is an optic suleus here. No mention is made of otic 
primordia, 
There are two excellent papers on the early sensory anlagen 
in the cat. The earlier work of Martin (90) can be best con- 
sidered in the light of the more complete and thorough studies of 
Schulte and Tilney (15). Here (p. 322) it is probable that the 
optic anlage was indicated in the three-somite embryo. The 
four-somite specimen had optic sulci which resemble those of 
man (fig. 9d) rather than the optic ‘foveolae’ of the pig. In both 
cases the neural folds were still open throughout their extent. 
In the older one they identified trigeminal and acousticofacial 
