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The independent regio olfactoria, formed in this way, which contains 
the olfactoria-conchae, terminates at the end blind against the frontal 
part of the praesphenoid. 
In an almost fullerown specimen of Ateles ater 1 found likewise 
an independent regio olfactoria, half a centimeter deep; it is also 
extant both in a museumpreparation of Cebus fatuellus (Fig. 2) and 
in a specimen of Hapale jacchus which I prepared myself. 
Cebus fatuellus. Museum-preparation 1906, N. 3. Frontal dish from the 
hindmost part of the nose-cavity, seen from behind. Enlarged 2/5 XX 3/4. 
l. cr. =lamina cribrosa;- G = palata; //= lamina terminalis; v. r. = its 
free rim to the front; 7.0. = regio olfactoria; 7.7. = regio respiratoria ; 
mt = maxilloturbinale; ¢.m. = concha media; f.c.@. = fossa cerebri anterior; 
s. fr. = sinus frontalis, s. 1m = sinus maxillaris; 0. f. = os frontale; 0. z. = 
os zygomaticum; m = maxilla. 
Among Catarrhini embryos of Semnopithecus do not show a vestige 
of lamina terminalis. Neither does an embryo of 47 mm. of Macacus 
cynomolgus do so; in younger Macacus-embryos I found sometimes 
a very little independent regio olfactoria. Nor has a young specimen 
of Semnopithecus entellus a vestige of lamina terminalis; a young 
animal with a shedding dental system of Macacus sinicus possesses 
on the frontal parietis of the praesphenoid a little protuberance, a 
last remainder of the lamina terminalis. 
So we see, that in Platyrrhini a Jacobson’s organ is extant 
and a reduced independent regio olfactoria, whilst in Catarrhines 
both are missing. Consequently the question presents itself whether 
this fact can give any information about the signification of the 
Jacobson’s organ. By cauterisation of the organ of a cat and 
