THE EVIDENCE OF THE THYROID GLAND 207 
epithelium of the uterus masculinus and its processes is extraordi- 
narily elongated, the chitin covering being thick. In these animals, 
then, the common chamber or uterus into which the genital ducts 
empty, which, like the corresponding chamber in the scorpion, 
occupies the middle region of the operculum, is a large and con- 
spicuous organ. Further, and this is a most striking fact, the 
uterus masculinus does not open direct to the exterior, but into the 
genital cavity, “which lies above the uterus, so that the latter is 
situated between the lower wall of the genital cavity and the outer 
integument.” The opening, 
therefore, of the uterus is not 
external but internal, into the 
large internal space known 
as the genital cavity. The 
arrangement is shown in Fig. 
91, taken from Tarnani’s 
paper, which represents a 
diagrammatic sagittal section 
through the exit of the male 
genital duct. Yet another 
most striking fact is described 
Fie. 91.—Saairtan Mepian Diagrammatic 
by Tarnani. This genital 
. Z Fe : SECTION THROUGH THE OPERCULUM OF THE 
cavity is continuous with the Mate TueLypHonus. (From TaRnant.) 
pulmonary or gill cavities OD The thick line is the operculum, composed of 
each side, so that instead of a two segments, I. and IJ. Ut. Masc., uterus 
single opening for the genital : masculinus ; Gen. Ch., genital chamber ; Int. 
ad d h td Op., internal opening; Ht. Op., external 
products ss one on each S1U€ — opening common to the genital and respira- 
for each gill-pouch, as would _ tory organs, 
be the case if the arrangement 
was of the same kind as in the scorpion, there is a single large 
chamber, the genital chamber, common to both respiratory and 
genital organs. 
This genital chamber, according to Tarnani, opens to the exterior 
by a single median opening between the operculum and the succeed- 
ing segment; similarly, a communication from side to side exists 
between the second pair of gill-pouches. I have been able to 
examine Hypoctonus formosus and Thelyphonus caudatus, and in both 
cases, in both male and female, the opening to the exterior of the 
common chamber for respiration and for the genital products was 
