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nasopalatinus, which can be followed to a distance of 36 sections of 
25 u. and lies nearly on the spot of the entrance of the Jacobson’s 
Riet. 
Cebus hypoleucus. Full-grown. Enlarged 25°/3. J. 0. = Jacobson’s organ; 
n. J.0. = nerve for the organ; J.k.=Jacobson’s cartilage; n.np.= Nerv. 
nasopalatinus ; S.7.=Septum nasi; #.8. = mucous membrane of the 
medial parietis of the nose-cavity; g. 8. = mucous membrane of the palate 
V = Vomer; m= maxilla; V = Veins. 
organ into the ductus nasopalatinus of Platyrrhini. This groove may 
be a rudiment of the Jacobson’s organ; in embryos of Catarrhines 
with young cartilage skeleton however, the Jacobson’s organ, which 
is then still extant, lies more dorsal. 
All the mentioned foetuses of Platyrrhini possess likewise a small 
lamina terminalis dividing the hindmost part of the nose-cavity into 
a reduced regio olfactoria and a regio respiratoria. 
The lamina terminalis is found in all mammals with a well devel- 
oped olfactoria organ. It separates in the hindmost part of the 
nose-cavity from its lateral parietis, divides the nose-cavity into two 
parts situated the one above the other, and fuses with the vomer. 
