938 
Anatomy. — “The development of the Fossa Sylvi in embryos of 
Semnopithecus.” By Dr. D. J. Hursnorr Por. (Communicated 
by. Prof. C. WINKLER.) 
(Communicated in the meeting of January 27, 1917). 
During the last years of my stay at Lawang-Java, I had the 
opportunity to shoot a great number of semnopithecus maurus in 
the woods on the slopes of the Tenger mountains. 
The uteri, which were taken out of the monkeys, which. were 
shot, were preserved in the beginning in formaline, but afterwards 
were brought in alcohol for the voyage to Europe. Later on too, 
after the brains were dissected from the skulls, they remained in 
alcohol. 
As a rather complete series of the brain of a monkey embryo 
is not- often found, it is comprehensible that the material which I 
collected, has given rise some new points of view. 
On the ape fissure and plis de passage I communicated already 
previously.*) In this communication the development of the fossa 
Sylvii is going to be described, which totally differs in certain points 
from what is found in human embryos. 
Therefore it is sufficient to describe the monkey embryos with 
the serial numbers 15—14—13a—13d—12—11 and 10, because 
the suleus in N°. 10 has already reached the full development and 
there totally agrees with what is found in adult specimens. 
Before I pass on to this, I will first recall to memory in short, 
how the development takes place in the human being. 
In the description given by EKKER*) was pointed out that in the 
3'¢ month, in which the brain has become 1,9— 2,6 cm, a curvature 
commences, as found in a bean, between the frontal and parietal 
part. This curvation continues at the base towards the lateral surface, 
and Ekker describes it on page 208 as follows: “stellt anfangs eine 
ganz flache etwa dreiseitige Grube dar, deren Spitze nach abwärts 
gegen die Hirnbasis, deren Basis nach Auswärts sieht.” 
In the 4" month the fossa Sylvii zs distinctly marked, as the 
brain matter begins to bulge alongside its rim: “welche nach unten 
und vorn gegen die Schädelbasis flach ausläuft.” 
1) D. J2 HutsHorr Por. The fissura simialis in embryos of semnopitheci. 
Royal Acad. of Science. Amsterdam Febr. 1916. The relation of the plis de 
passage of gratiolet to the ape fissure R. A. of S. April 28, 1916, and the ape 
fissure — Sulcus Lunatus — in man. May 27, 1916. 
2) A. Exxer. Zur Entwicklungsgeschichte der Furchen und Windungen der 
Grosshirn hemisphiren im Foetus des Menschen. Archiv f. Anthropologie 1868. 
