390 THOS. H. MONTGOMERY jr., 
II. Cuticula. 
The cuticle covers the whole external surface of the body, and 
is continued inwards along the cloaca, in both sexes. It is a formation 
of the hypodermis. The superficial appearance of it and the distribution 
of its areoles have been described by me elsewhere (MONTGOMERY, 
1898), so that it is not necessary to redescribe them. 
At all points on the external surface the cuticle shows two distinct 
layers, which may be described separately as the inner or fibrous, and 
the outer or non-fibrous cuticula. 
The fibrous cuticula which lines the outer surface of the 
hypodermis, is composed of successive layers of fibres. The fibres of 
one layer are all parallel, and their long axes cross the long axis of 
the body at an angle; the fibres of the next layer cross those of the 
former at an angle (Fig. 40, Pl. 39, on surface view where the arrow 
denotes the long axis of the body). They are thus not arranged in 
concentric circular layers as a hasty examination of cross sections 
would lead one to suppose. Cross sections (F. Cut Figs. 37, 41, Pl. 39) 
show that each layer of fibres has a definite boundary, and contains 
its fibres arranged in a single row; and these cross out fibres appear 
rounded or more often primatic. The number of these layers is 
. greatest where the cuticle is thickest, and in the female there are as 
many as eleven of these layers. Besides these layers of finer fibrils, 
are found not continuous but irregularly disposed layers of larger 
fibrils (Fig. 37). This fibrous cuticle has a very elastic and firm con- 
sistency, and no radial pores or canals were found in it even after 
the closest examination. It is thinnest on the ventro-lateral sides of 
the head (F. Cut Fig. 10, Pl. 37), where its layers are also very thin 
but apparently as numerous as elsewhere; on the outer surface of the 
tail lobes of the female it is thinner than in other parts of the trunk, 
and contains fewer layers (Fig. 41 F. Cut). It is everywhere sharply 
demarcated from the underlying hypodermis (Hyp), so that in the 
free state of the animal its process of formation is complete. The 
black cervical ring at the anterior end of the animal is due to a 
dark color of the deeper layers of the cuticle in that region (Figs. 1, 
4, Pl. 37). 
The fibrous cuticle of the male differs from that of the female in 
being thicker and containing more layers. In the male particularly 
on the ventro-median surfaces of the tail lobes are found imbedded 
in the fibrous cuticle small, rounded bodies which stain deeply with 
