186 
F. M. BALFOUR. 
(3) A ventral anterior region. 
The central region contains in its interior the cornnhs- 
saral portion, forming a punctifonn, rounded mass in each 
ganglion. A transverse commissure connects the two {vide 
fig. 20 If). 
The dorsal hemispherical lobes are derived from the part 
which, at the earlier stage, contained the semicircular 
grooves. When the supra-oesophageal ganglia become sepa- 
rated from the epidermis the cells lining these grooves 
become constricted off with them, and form part of these 
ganglia. Two cavities are thus formed in this part of the 
supra-oesophageal ganglia. These cavities become, for the 
most part, obliterated, but persist at the outer side of the 
hemispherical lobes (figs. 20 a and 21). 
The ventral lobe of the brain is a large mass shown in long 
section in fig. 21. It lies immediately in front of and almost 
in contact with the ganglia of the chelicerse. 
The two hemispherical lobes agree in position with the 
fungiform body (pilzhutfdrmige Korpern), which has attracted 
so much the attention of anatomists, in the supra-oesophageal 
ganglia of Insects and Crustacea; but till the adult brain of 
Spiders has been more fully studied it is not possible to state 
whether the hemispherical lobes become fungiform bodies. 
Hatschek^ has described a special epiblastic invagination 
in the supra-oesophageal ganglion of Bombyx, which is pro- 
bably identical with the semicircular groove of Spiders and 
Scorpions, but in the figure he gives the groove does not 
resemble that in the Arachnida. A similar groove is found 
in Peripatus, and there forms, as I have found, a large part 
of the supra-oesophageal ganglia. It is figured by Moseley, 
^ Phil. Trans.,’ vol. 164, pi. Ixxv, fig. 9. 
The stomodseum is considerably larger than in the last 
stage, and is lined by a cuticle ; it is a blind tube, the blind 
end of which is the suctorial pouch of the adult. To this 
pouch are attached the vertical dorsal, and two lateral muscles 
spoken of above. 
The proctodseum (/?r.)has also grown in length, and the two 
Malpighian vessels which grow out from its blind extremity 
(fig. 20 e, mp. g.) have become quite distinct. The part now 
formed is the rectum of the adult. The proctodaeum is sur- 
rounded by a great mass of splanchnic mesoblast. The mesen- 
teroii has as yet hardly commenced to be developed. There 
is, however, a short tube close to the proctodaeum (fig. 20 
7/IC5), which would seem to be the commencement of it. It 
* “ lieitrjige z. Eiitvvick d. Lepidopteren,” ‘ Jenaische Zeit.,’ vol. xi, 
p. 124. 
