474 B. F. KINGSBURY 
in the neighborhood of the tectum mesencephali, although there 
is clearly considerable variation in this respect. The closure of 
the neural tube progressing cephalad (as well as caudad) leaves 
a slit-like opening of the neural tube anteriorly (chick of eight 
to nine somites; cf. figs. 27 to 29). Its ventral extremity lies 
at the site of the future preoptic recess. Due to the expansion 
of the dorsal portion of the neural tube in this region, it is from 
the beginning in part ventral in position. Figure 33 is from a 
model of the anterior portion of the head in a chick of eight to 
nine somites as seen from the ventral side. Its ventral extremity 
likewise marks the anterior medial boundary of the neural plate. 
The suture closes rapidly and apparently last at or near its dorsal 
extremity, although again there appears to be some variation in 
different forms and individually. To this entire opening from 
the earliest stage the term ‘neuropore’ is frequently applied, 
while others would limit the term to the point of final closure. 
Possibly it would be well to distinguish these as primitive neuro- 
pore and definitive neuropore, respectively. 
Inasmuch as the bordering edge of the neural plate in this 
region marks the lamina terminalis, it would seem that a separate 
designation would be of value for descriptive purposes. It 
should, however, be appreciated that essentially it is but the most 
anterior portion of the sutura dorsalis given a peculiar significance 
through the growth expansion of the adjacent portion of the brain 
(and head). 
It may be remarked that Lillie (19) correctly describes in the 
chick the anterior relations of the sutura terminalis (pp. 105, 
147). The interpretations of Schulte and Tilney (15) are as 
obviously wrong. Johnston (’11) has quite adequately discussed 
this region (p. 39) and with what he there states my observations 
agree. 
3. The sutura neurochordalis (ventralis) 
The His conception of the origin of the body through the ap- 
position or concrescence of a germ ring is of course well known. 
The idea was an old one with him and appears as early as 1874, 
prompted by his work on the development of the salmon and 
