418 THOS. H. MONTGOMERY jr., 
sections several could be seen on both sides of the mid line. There 
is accordingly no regular pairing of these nerve fibres, nor any regular 
arrangement of them beyond that they are placed close behind each 
other, that the number of them is approximately the same on the 
two sides of the body, and that in the anterior trunk region they are 
more numerous than in the posterior. The longitudinal vertical sections 
which show these nerves in the neural lamella before they have entered 
the hypodermis (Fig. 31, Pl. 39), as well as horizontal longitudinal 
sections of this lamella (Fig. 33), show that in the lamella also they 
are not regularly paired but for the most part are placed one behind 
the other. 
Sensory nerve cells of the hypodermis. There are two 
main forms of these. The first are small, very irregular cells (Sen. C 
Figs. 22, 24, 25, Pl. 38), which with iron-haematoxylin stain in- 
tensely black, cytoplasm as deeply as the nucleus, while with DELA- 
FIELD’s haematoxylin the nucleus stains much deeper than those of 
the cuticular cells of the hypodermis. The nucleus is much smaller 
than that of the cuticular cells, and is generally very irregular in 
outline; and the cell body is still more irregular in form, and con- 
siderably smaller than that of the cuticular cells. Often the cell 
appears pyriform or irregularly elongated, thickest around the nucleus, 
and is in general bipolar. Peripherally an elongation extends towards 
the cuticula of the hypodermis, while from the opposite pole one or 
several delicate irregular processes arise and appear to break into 
delicate plexuses. In one case a process of such a cell could be followed 
to the base of the neural lamella (Fig. 22, right side). Such cells are pro- 
bably sensory, since no other function can be well ascribed to them, and 
since their processes and plexuses seem to stand in an intimate re- 
lation to the chromophilic nerve elements of the hypodermis. In no 
case were any processes of them to be followed into the cuticula (and 
in fact in no region of the body could an innervation of the cuticula 
be determined). On account of their very irregular form they may 
be more or less degenerate in the adult condition. These cells appear 
to be very abundant in the hypodermis, especially on the sides of 
the body. With them must not be confused the degenerate gland 
cells, elsewhere described. 
The second kind of sensory cells of the hypodermis are the 
elongated cuticular cells of the mid-ventral line (Fig. 13, Pl. 37; 
Figs. 15, 17, Pl. 38), which reach their greatest height in the head 
region and caudad from that point diminish gradually in size. These 
