143 
Variations in Uroi^oda. By A. D. Michael. 
of the last-named family was entirely absent, being to some extent 
replaced by the curious and elaborate organ which I called the 
‘‘ vestibule ” ; there was, however, this essential difference, viz. that 
the ovipositor of the Orihatidm is a long, protrusible organ, which, 
when in action, is almost wholly outside the body, like the ovipositors 
of Insects, although it is withdrawn into the abdomen at ordinary 
times ; while the vestibule of the Uro 2 )odinie is merely a passage 
leading from the vagina to the exterior ; and is, at all times, wholly 
within the body and entirely incapable of protrusion ; it is, however, 
not a simple chamber, but is of an elaborate nature, and has more or 
less complex organs surrounding it. 
In the autumn of 1889 I had opportunities of obtaining some 
species of Uropoda in considerable numbers, and I thought this 
would be a favourable opportunity for ascertaining whether the 
vestibule in the females of other species of the genus were similar to 
that of U. Krameri. On investigation I found that, although the 
ovary, oviducts, and vagina varied but little, yet that the vestibule 
and surrounding organs did not really agree in any two species ; the 
differences were often very marked, the type of U. Krameri not being 
repeated anywhere. It is a few of the more remarkable of these 
variations which I propose to describe in this paper. 
The two principal species which I have examined have been 
those which I call U. ovalis Koch, and TJ. vegetans de Geer. In 
tube, retractor muscles of the same. mc7, mandibles, m**, retractor 
muscles of same. palpus, ge, great oesophageal ganglion (so-called 
brain), r/d, distensor muscles of oesophagus. 
Fig. 12. — Uropoda vegetans $. Whole genital system seen from the dorsal (upper) 
surface, x 80. This figure is turned in the reverse direction from the 
others. 
„ 13. — Ditto. Vestibule and surrounding parts, seen from the ventral surface, 
looking upward through the genital aperture, the genital plate having 
been removed. In order to make this figure clearer the receptaculuiu 
seminis and sigmoid piece have been removed from the right-hand side 
of the figure (proper left of the creature), and the accessory gland from 
the left-hand side (proper right of the creature), df, depressed marginal 
border of thin chitin forming a stop for the genital plate, against which 
it rests. 
„ II. — Ditto. A small portion of the left side of the same organs seen from the 
dorsal surface, to show the entry of the duct of the receptaculuiu seminis 
into the upper part of the neck of tlie vagina, x ICO. 
„ 15. — Ditto. Left sigmoid piece and some of the surrounding organs, partly side 
view, from below, x IGO. 
„ 16. — Ditto. Epigynum, &c., seen from dorsal surface, X 100. 
„ 17. — Ditto. Sigmoid piece detached and seen from a nearly dorsal direction, 
X 200. 
„ 18. — Ditto. A small portion of the heel of the perigynum, x 350, to show the 
nature of the spines. 
„ 19. — Ditto. Thin chitinous piece supporting the membranous continuation of 
the lower edge of the vagina, x 180. 
„ 20. — Ditto. A few spermatozoa released from the receptaculuiu seminis, x 200. 
„ 21. — Ditto. One receptaculum seminis and duct detached. 
„ 22. Uropoda cassidea $. Perigynum and surrounding organs, seen from the 
upper (dorsal) side, x 160. 
