206 BULLETIN OF THE 
EXPLANATION OF FIGURES. 
ABBREVIATIONS. 
a. Anterior. n. for. Nerve fibre. 
can. po. Fine pore-canals. n. opt. Optic nerve. 
can. po.’ Coarse pore-canals. nl.msd. Nucleus of mesodermic cell. 
cav. Cavity of infolding. nl. pig. ie pigment 
cl. pig. Pigment cell. nl. pin. = perineural “ 
col. Neck of invagination. nl. pr. § postretinal “ 
enc. Brain. nl. pr r. oe lentigen os 
env.em. Embryonic envelop. nl. r. og retinal “ 
gra. pig. Pigment granule. p- Posterior. 
hd. Hypodermis. pha sp. Phaosphere. 
ir. Tris. pr Post-retina. 
ll. Outer hyaline layerofcuticula. prr. Lentigen. 
W.. - Middle ' .* “ oo Retina. 
We Deep Fs fs g rhb. Rhabdome. 
Ins. Lens. rhb m. Rhabdomere. 
mb. Basement membrane. sel. Sclera. 
mb. pr 7. Preretinal # 1,2,3,4,5. Lateral eyes. 
mu. Muscle. 
All the figures were drawn with the aid of an Abbé camera. Except where 
otherwise specified, all the preparations were examined in benzol-balsam. 
Figures 1 to 18 represent the structure of the median eyes. Figures 1 to 9 
illustrate the adult eye. 
PLATE I. 
Fig. 1. A horizontal section of the retinas of the two median eyes seen from the 
dorsal side. The tissue has been simply hardened and cut, the pigment 
remaining intact, and no dye being employed. X 195. 
Fig. 2. A transverse section of the retina of the right median eye seen from the 
posterior face. The pigment has been removed by potassic hydrate 
and the tissue stained in Grenacher’s alcoholic borax-carmine. X 195. 
PLATE II. 
Fig. 3. The outer face of a frontal section through the retina of a median eye. 
The portion of the figure nearer the right side is close to the centre of 
the retina, that to the left is nearer the periphery. Colored with Klei- 
