116 
Loa papionis n. sp. 
The cuticle and subcuticular layer. When fixed and cleared as above 
described, the cuticle is seen to be composed of two layers, of which the internal 
is thicker than the external. In the male, the internal layer shows an exceed¬ 
ingly fine ringed striation for the posterior 2 to 3 mm. which is visible both in 
the living worm and after fixation in hot alcohol; a less distinct but otherwise 
similar striation is sometimes to be seen in the female. The coarse striae 
described by Ludwig (1895) result from muscular contraction, and can be seen 
to appear and disappear during the movements of the living worm. They may 
be preserved in places after fixation in cold alcohol, but are never visible after 
fixation in alcohol at 60° C. 
The maximum thickness of the cuticle is distinctly greater in the female 
than in the male: however, for L. loa, Penel (1904) and Looss (1904) give an 
identical measurement for both sexes (Table I). The cuticle is much thinner 
at the extremities (3 to 6p, in the 4 to 8p, in the 2); moreover it is thicker 
over the anterior extremity than over the sides of the cephalic cone (Plate IX, 
fig. 1, Cut.). In the case of L. loa, observers are not in agreement on these 
points: Looss (1904) represents the cuticle as being of equal thickness in both 
situations, while Blanchard’s drawing (1889) which is reproduced by Fan- 
tham, Stephens and Theobald (1916), more nearly corresponds to what 
I saw. 
The cuticular bosses are very similar in appearance and distribution to 
those described for L. loa. They commence in both sexes at a variable distance 
behind the anterior extremity (0-71 to 2-5 mm. in the g, 1-2 to 3-5 mm. in 
the $). They are rather scanty in the <J, being altogether absent from the 
posterior 0-54 to 1*7 mm.: numerous in the $, they frequently show a tendency 
to be concentrated in small groups, and always reach the tip of the tail or 
thereabouts. In both sexes the bosses vary in size in different specimens, but 
are always larger in the $ (Table II). They almost invariably look clear and 
structureless but I have seen the appearance of an internal papilla. 
Table II. 
Measurements of the cuticular bosses compared in both sexes. 
Height of bosses Diameter at base 
in microns 
in microns 
No. 1 
3- 6 
8-14 
No. 2 
3-10 
8-20 
No. 3 
3- 8 
8-20 
No. 1 
8-16 
14-24 
No. 2 
4-10 
12-22 
No. 3 
6-20 
14-22 
The size of the clear, anterior area—the so-called cephalic cone —(Plate IX, 
fig. 1, c.c.) varies slightly in different specimens, but in both sexes the base 
of the cone measures from two and a half to three times the length of the 
vertical diameter. 
