428 ‘ THOS. H. MONTGOMERY jr., 
mental “Lateralnerven”, nor any conjunction of nervous with muscular 
tissue. He also doubts the nervous nature of the neural lamella, but 
grants the possibility that at intervals fine nerve fibres may penetrate 
into this lamella. 
von Linsrow (1889) describes the nervous system of G. tolosanus, 
but makes no reference to the cells that compose it. 
VII. The Eye. 
In both sexes there is found in the anterior region of the head, 
above the oesophagus, a large entirely closed sack (E. Cav Figs. 1—4, 
6, Pl. 37), the exact dimensions of which vary somewhat in different 
individuals. Its anterior wall is made up of much elongated hypo- 
dermal cells (EZ. Hyp), which extend backwards. Elsewhere it has a 
sheath or capsule (E. Cap) of dense and firm consistency, inserted 
anteriorly into the hypodermis (Hyp), and thickest at its most 
posterior part; this may be called the eye capsule. The interior of 
the sack is filled with a thin, pale-staining fluid (appearing as a 
coagulum [Coag Fig. 6] on preserved material), in which lie numbers 
of small cells, which may be termed the retinal cells (Ret Figs. 2, 
3, 6); these are generally limited to the posterior portion of the 
cavity and there usually placed close to the inner surface of the capsule. 
Into the thickened posterior region of the capsule pass a pair of large 
nerve fibre bundles (Dors. N Figs. 2, 3, 6) coming on either side of 
the oesophagus (Oes) from the dorsal surface of the cephalic ganglion, 
and which may been termed above the dorsal nerves. The oesophagus 
below and hypodermis dorsally and laterally are separated from this 
organ by parenchym (Par Fig. 6). 
The anterior hypodermal elements. These (E. Hyp 
Figs. 1, 6, 10, 11) are much elongated cylindrical cells, a modified 
type of the cuticular cells, and extend backwards; the inner surfaces 
of them are directly bathed by the fluid of the sack. Each contains 
one nucleus (N Figs. 10, 11) placed generally in the proximal third 
of the cell, and containing one or two true nucleoli; it is generally 
rounded in outline. The cytoplasm is finely alveolar and somewhat 
refractive next to the cuticula, elsewhere more or less coarsely vacuolar, 
generally so that one or two large vacuoles (Vac) lie near the nucleus 
and smaller ones in other portions of the cell body. Cross sections 
(Fig. 9) show very clearly that the periphery of the cell is composed 
of a dense layer of cytoplasm, while the axial cytoplasm is more 
