1577 
The conclusion, to which we now may come, is therefore: 
1. that, up to this period of development, there is no question 
of an ape-fissure ; 
2. that, as I already mentioned previously, in opposition to the 
opinion of KükeNTHAL, Zieuen and KonrBrueer, the sulci inter- 
parietalis (/ + e) and par. oee. lat. (m + m?) commence as one single 
furrow. 
If one looks attentively at fig. 6, then it is proved that on the 
whole of the brain the lips of the sulci lie closed against each other, 
except those, belonging to the s. parieto oce./ lateralis (mm —- mn’) 
which are totally rounded, which can be caused by the greater 
development of the hind-lips, and when they are higher raised. 
Fig. 7 (embryo length 19,5 cm., weight 189 gr.) is of much 
importance to us. We here see again, that the hindlip of the s. 
parieto-oce. lat., protudes still more; moreover that in the posterior 
part of the arcus par. oce. a curve appears, (to the right distinetly 
visible at +). The commencement therefore of the ape-fissure. 
By fig. 8 (embryo length 23,5 em., weight 251 gr.) the ape-fissure 
is still more developed. Where it is opened at the left side, one 
distinctly sees that it represents a furrow. At the right side I opened 
the fissura simialis somewhat more and two important things are 
seen in it. First that the 7 + m' furrow lie for the greater part 
totally superficially and that the m* suleus is still separated by a 
thin convolution from the medial face. Secondly it is seen that the 
posterior part of the arcus par. oec. (1st pli de passage of GRATIOLET) 
is pushed into the depth (0), but that it is still totally intact. The 
anterior part of the arcus still lies on the surface (00). The only 
difference between fig. 7 and 8 is therefore that the posterior part 
of the arcus, inclusive the incisure, has penetrated further to the 
