458 THE INSECTA. $$ 852, 853: 
moment of their escape from the vagina, and in this way the eggs are cole 
lected in masses to be deposited in places fit for their incubation.” 
II. Male Genital Organs. 
§ 352. 
The Testicles, which are double like the ovaries, consist, sometimes of 
two simple caeca, which are more or less long and torose, and sometimes 
of many caeca, very variable as to their forms and disposition. Their 
mode of grouping resembles that of the ovaries; indeed, their whole 
appearance and contour, and the number and composition of their various 
parts resemble remarkably those of the female organs. With many spe- 
cies, these organs are covered by a lively-colored pigment layer, or envel- 
oped by a special membrane (Tunica vaginalis). 
The two Vasa deferentia are of variable length, often exceeding that of 
the body, and therefore making several convolutions in the abdominal cav- 
ity. When the testicles are composed of many caeca, there are often the 
same number of these canals; but they often unite, on each side, into a 
common duct. Sometimes they have, each, at their lower extremity, a 
vesicular dilatation which may be regarded as a Vesicuwla seminalis. At 
their point of junction on the Ductus ejaculatorius, there are usually situ- 
ated two, longer or shorter, simple Glandulae mucosae, which secrete a 
quickly coagulating, granular mucus, which serves, during the copulatory 
act, partly to fill and distend the Bursa copulatriz together with the 
penis, and partly to surround portions of the sperm, and thereby form 
spermatophores. 
§ 353. 
The principal modifications observed with the internal male organs of 
the Insecta, are the following. 
‘Among the Aptera, Lepisma is distinguished in having numerous oval, 
testicular follicles, whose Vasa deferentia, after forming irregular ramifica- 
tions, unite in two common excretory ducts, which, gradually enlarging, 
terminate in a Ductus ejaculatorius at the point of ‘insertion of two arcu- 
ate accessory glands. 
With the Hemiptera, the internal genital organs are of very variable 
form.® The Pentatomidae have only two simple, pyriform testicles, often 
of a beautiful red color; at their free extremity they sometimes have 
several constrictions, snd thus form the passage to the form proper to 
many Geocorisae, which have seven long testicular tubes united in a fan-like 
7 The ovigerous groove is short and triangular 
with Libellula vulgata and cancellata ; long, 
acuminate, and perpendicular with Cordulia me- 
tallica ; long and cordately emarginate and closely 
applied against the abdomen with Epitheca bimac- 
ulata. A remarkable appendage, deeply exca- 
vated, situated to the exterior of the female genital 
organs of Doritis Apollo and mnemosyne, and 
upon which, as yet, no lepidopterist has given any 
details, is probably an ovigerous sac. 
1 For the various forms of the simple and com- 
pound testicles, as wellas for the male organs of the 
Insecta in general, see Burmeister, Handb. &c. 
I. p. 217, and Lacordaire, Introduct. &c. II. p. 
305. 
1 See Treviranus, Verm. Schrift. II. p. 15, Taf. 
IV. fig. 2. The Pediculidae have only two ‘pairs 
of testicles. 
2 See L. Dufour, Recherch. sur les Hémipt. Ph 
X.-XIiI. 
