All the figures were drawn with the aid of a camera lucida. 
ESTERLY: 
EUCALANUS. 
oD) | 
ce) | 
Explanation of Plates. 
In general, 
dark tones are to be interpreted as meaning that the structures so represented 
are at a higher focus in the preparation than those shown in a lighter tint. 
This is particularly true of the “‘interior bodies”’ and nuclei; simple lines need 
All figures are of Eucalanus elongatus. 
not necessarily be so looked upon. 
Dana. 
a. &. 
cb. 
cl. ©: 
cle. 
d. 
dx. 
for. 
h’drm. 
la. ba. 
mb. ba. 
mb. pin. 
m., 
n. at. 
nw fori. 
nl. 
. Nucleus of retinal cell. 
ABBREVIATIONS. 
. Anterior. nl’, 
. Brain. 
. Central (pigment) cell. ne 
. Cell of brain. 
. Dorsal. nl.h’drm. 
. Right. n. opt. 
. Fibre (or fibres) of optic  n’pil. 
nerve. 
. Hypodermis. o. Claus. 
. Basal plate. ocl. dx. 
. Basement membrane of hy- —_ocl. m. . 
podermis. 
Membrane surrounding op- _ocl. s. 
tic nerve. Dens 
. Nerve from organ of Claus. par. cp. 
. Antennal nerve. pha’so. . 
. Frontal nerve. 
. Neurofibrillae. Stes 
tap. 
. Nucleus of central 
. Nucleus of cell of organ of 
Claus. 
(pig- 
ment) cell. 
Nucleus of hypodermal cell. 
. Optic nerve. 
. Neuropil entered by optic 
nerve. 
Organ of Claus. 
Right ocellus of median eye. 
Median (ventral) ocellus or 
median eye. 
. Left ocellus of median eye. 
. Posterior. 
Body wall. 
Phaosomes or 
bodies.”’ 
“Tnterior 
. Left. 
. Tapetum. 
