OBSERVATIONS ON THE NERVOUS SYSTEM OF APUS. 443 
EXPLANATION OF PLATE XXX, 
Illustrating Mr. Paul Pelseneer’s Paper on “ Observations on 
the Nervous System of Apus.” 
Fig.1. — Left half of the anterior part of the nervous system of Apus. 
c. Brain. N o. Optic nerve, c a. Abdominal cord, a i. Nerve of the first 
antenna, a n. Nerve of the second antenna. ra. Elongated swelling, 
c n. Nervous cell. 
Fig. 2. — Beginning of the second antennary nerve, c a. Abdominal cord, 
All. Nerve of the second antenna, ga. Ganglion of the second antennary 
nerve. N s. Stomato-gastric nerve; ra. Elongated swelling (ganglion of the 
stomato-gastric nerve), c 1 and c 2. Anterior and posterior commissures 
of the elongated swelling. 
Fig. 3. — Anterior part of the nervous system of Apus, side view. c. Brain, 
o. Bight eye. o i. Median (larval) eye. c a. Abdominal cord. B. Mouth. 
T g. Digestive canal, a i. Beginning of the first antennary nerve, a ii. Be- 
ginning of the second antennary nerve. 
Fig. 4. — Vertical projection of the brain of Apus. 1 o. Right optic 
nerve, o i. Median (larval) eye. a. Anterior cellular mass, g 1. First right 
ganglionic group (primitive cephalic ganglion), g 2. Second right ganglionic 
group (ganglion of the first antennary nerve), c a. Abdominal cord. 
Fig. 5.— Horizontal projection of the brain of Apus. ap. Posterior mass 
of small cells, oi. Nerves of the larval eye. 6 — 6. Line showing the 
direction of the section drawn in Fig. 6. 7 — 7. Direction of the section drawn 
in Fig. 7. Other letters as for Fig. 4. 
Fig. 6. Transverse section of the brain of Apus, passing through the 
line 6 — 6, Fig. 5. g 1. First ganglionic group (primitive cephalic ganglion), 
c s. Superficial lining of small cells. 
1 In this projection, and in the following, the thin layer of small cells 
forming the superficial coating of the brain has not been drawn (see c s, Figs. 
6 and 7). 
