1881.] | The Brain of the Locust. ‘ 301 
LETTERING OF THE FIGURES ON PLATES I—V. 
centr, b., central body. 
trab,, trabecula. 
cau., cauliculus 
psg., posterior ee aae ganglion. 
lat, n., eae 
. centr. n., cen aie nerve 
ped., peduncle, obl, tr. n., peerarte trabecular nerve. 
0. cad., outer calyx, or cup. gy i ascending trabecular nerve. 
z. cal., inner calyx. 
op. 1, optic lobe. 
op. n., optic ner 
ant, fs antennal ‘viii 
ant. n., antennal nerve. 
m. n., two median cents nerves. 
sup. n., Superior commissural nerve. 
in,. n., inferior commissural nerve. 
tr, tiaehided 
up. d., upper cerebral lobe of embryo. 
@. com. l., esophageal commissural lobe. | dow. /., lower age lobe of embryo. 
@. com, n., cesophageal commissural | gang. c., ganglion cell 
nerve, gran., granules of “a central nervous 
@. ¢., esophageal commissural nerve, matter, 
lor. ., nerve to labrum. @s., oesophagus. 
4. g. ¢., large ganglion cells, zn¢,, integument. 
$. g. ¢., small ganglion cells. o. ., ocellar nerve; oc., ocellus. 
opt. gang., optic ganglion, 2. c., ventral nervous cord 
Sg. ., sympathetic nerve. rE nucleolus. 
4, m., transverse nerve , labrum. 
u. intr. n., wpper Gaiondvats ches nerve. we ear 
/, intr. n., lower intratrabecular nerve. = lab 
dn., nerve to labium. eine 
Jg., frontal ganglion. 
EXPLANATION OF PLATE I. 
Fic. 1.—Front view of the brain of Caloptenus femur-rubrum. 
Fic, 2.—Side view of the sa 
Fic. 3.—Side view of the fick: showing the relation of the brain to the mouth (m) 
_ and cesophagus (@) and walls of the head 
Fig. 4 —The brain as seen from above, and the three ocelli. 
Fic. 5.—The subcesophageal ganglion seen from above. Drawn by E. Burgess. 
DESCRIPTION OF PLATE II. 
Fic. 1.—Frontal section 16, through the front of the brain of adult Caloptenus spre- 
sus; X% ¥% inch objective, A. eye-pi 
Fic. 2. eines 17, showing the central es (centr. 6.) and mushroom body, optic 
and antennal lobes, and commissural lobes; BA. 
Fic. 3.—Enlarged view of the trabecula and its acces of the mushroom body, its 
calices and stalk, and the origin of the optic nerves; X } A., 225 diameters. 
Fic. 4.—Section 18, passing through the back of the central body, shewing the dou- 
ble nature of the stalk of the mushroom body, and passing through the back of 
the commissural lobes and behind the trabecula and the base of the stalk; X 
4 A. Are oc, n. ? the origins of the ocellar nerves? : 
Fic. 5.—Vertical (longitudinal) section through ore of the hemispheres, showing 
the origin of the commissural and antennal nerves and the optic lobe 
Fic, 6.—Longitudinal section through the brain and subcesophageal pepe: (X 50 
diameters), showing the tw o portions of the calyx, the antennal lobe, and in the 
subcesophageal ganglion the three lobes giving off respectively the mandibular, 
maxillary, and labial nerves, 
