396 THOS. H. MONTGOMERY jr., 
irregular mass of secretion being usually all that is left to mark the 
gland cell. The formation of the fibrous layer of the cuticle would 
appear to have caused their degeneration, by hindering the outflow 
of secretion. In the more anterior trunk region where the hypodermis 
is still more degenerate, are found only small dark bodies to represent 
these cells. But probably it will be found by a study of the embryo- 
logy that on an earlier stage these gland cells are found in the whole 
trunk region, and degenerate last on the surface of the tail lobes. As 
has been suggested in the section “Cuticula”, the areoles of the cuticle 
may represent masses of secretion poured out by these gland cells 
before the formation of the fibrous layer of the cuticula. 
In the male the hypodermis of the head region is as in the female, 
but in the anterior trunk region the medio-dorsal thickening is much 
more pronounced (Fig. 83, Pl. 42; Fig. 90, Pl. 43). Through the 
greater portion of the trunk region it appears to be much the same 
as in the female, although I have not examined it so carefully in the 
male, except that the cuticular cells of the medio-dorsal thickening 
are proportionately very large with large rounded nuclei. But the 
structure of the hypodermis on the tail lobes of the male is quite 
different. The hypodermis on the dorsal and outer aspects of these 
lobes is not striated nor heightened, but much as in the more anterior 
regions of the trunk; and the latero-ventral hypodermis, next to the 
caudal nerve, is much heightened and sensory (Hyp Fig. 48, Pl. 39; 
Figs. 46, 47, Pl. 40), some cells of a type not found in the female 
(cf. the section “Nervous system”). 
Literature on the hypodermis. VEJDoVskY (1886) finds 
the “hypodermis” to be a true epithelium in the anterior and posterior 
body regions, elsewhere “eine feinkérnige, mit zerstreuten Kernen ver- 
sehene Matrix”; only one kind of cells were noted by him. In another 
paper (1894) he describes the metamorphosis of the hypodermis, finding 
true gland cells in it, and shows it to be very degenerate in the adult 
condition, due to the gradual formation of the fibrous layer of the 
cuticula. VILLOT (1874) considers the hypodermis to be a peripheral 
nervous layer, made up of a network of ganglion cells; in another 
paper (1887) he reiterates, in opposition to VespovsKy, that there 
is no nucleated hypodermis in the adult, but a fibrillar layer of 
nervous nature; and finally (1889a) he concludes that there is a true 
cellular hypodermis in young stages, and that subsequently the cells, 
“ramifiées et anastomosées, ne représentent pas, comme je l’avais cru 
