THE EVIDENCE OF THE THYROID GLAND 205 
is seen in Fig. 89. In Fig. 88 the section shows at } the holes in 
the chitin in which the cones terminate, and then a series of layers 
of sections through the cones further and 
further away from their apices. 
These conical groups of long cells, repre- 
sented in Fig. 87, form on each side of the 
uterus a gland, which is continuous along 
its whole length, and thus forms a line 
of secreting surface on each side, just as Fic. 89.—Transvmrsz Suc- 
in the corresponding arrangement of the TION THROUGH THE BasaL 
x : Part oF THE UTERINE 
glandular structures in the thyroid of Am- Cecsiseutanetsa Ban nevon. 
moccetes. This uterus and glandular ar- 
rangement is found in both sexes; the gland is, however, more 
developed in the male than in the female scorpion. 
The resemblance between the structure of the thyroid of Ammo- 
ccetes and the uterus of the scorpion is most striking, except in two 
respects, viz. the nature: of the lining of the non-glandular part of 
the cavity—ain the one case ciliated, in the other chitinous—and the 
place of exit of the cavity, the thyroid of Ammoccetes opening into 
AMMOCCETES. SCORPION. 
Muco-cartilage Operculum 
Branchial cartilage 
Fic. 90.—Sucrion or CENTRAL CHAMBER OF THYROID OF AMMOCGITES AND SECTION 
oF Uterus oF SCORPION. 
the respiratory chamber, while the uterus of Scorpio opens direct to 
the exterior. 
With respect to the first difference, the same difficulty is met 
