462 THE INSECTA. $ 354. 
‘ular apparatus consists of only two simple, longer or shorter caeca,“ 
which are sometimes quite long and torose.“” Another series of Coleop- 
tera have four to eight caecal appendages, disposed in pairs, and variable 
as to length and volume. One of these pairs is probably only a reservoir 
for the secreted product of the others.“ The Ductus ejaculatorius is 
always very muscular, and with very many species, quite long and flexu- 
ous, and the penis therefore can be widely protruded during copulation. 
§ 354. 
The Copulatory organs of the male Insecta are valve-like or forficulate, 
horny appendages,” which are so variable in their form that the most 
allied species differ, in this respect, widely and constantly. 
Beside these proper copulatory organs, situated at the posterior extremity 
of the abdomen, there are often on the antennae, the parts of the mouth, 
the legs and other regions of the body, auxiliary organs used for seizing 
and retaining the female, and which have long been objects of careful 
description in zoology. 
With most Hemiptera, the posterior extremity of’the abdomen conceals 
a horny capsule which contains a protractile, tubular penis. With very 
many Diptera, the copulatory organs project prominently in the same 
region of the body, and consist often of two horny valves of different forms 
which envelop a rather long pefiis.© The Lepidoptera, Hymenoptera, 
Orthoptera, and Neuroptera, have two pairs of valves, one internal, the 
other external, which enclose a tubular or groove-like penis. 
The Ephemeridae and the Strepsiptera, only, are distinguished by their 
very simple copulatory organs; for with the first there is only a simple 
penis without a valvular apparatus. This last is replaced by two long, 
small, triarticulated stylets, situated on the penultimate abdominal seg- 
ment and curved inwardly; while with the Strepsiptera, the penis, also 
naked and horny, is so articulated that it can be applied laterally against 
the abdomen, like the blade of a knife in its handle. 
With the Libellulidae, however, the orifice of the Ductus ejaculatorius is 
most simple, being covered only by two very small oval valves. 
But the 
penis is not wanting with these Insecta; it is singularly concealed, together 
with a horny-walled seminal vesicle, in a fossa situated at the base of the 
40 With the Carabidae, Hydrocanthari, and with 
Mordella, Anthribus, Galeruca and Coccinella. 
41 Melolontha, Cetonia and Lucanus ; see L. 
Dufour, Straus, and Suckow, loc. cit. 
42 With the Staphylinidae, Cantharidae, Byrrhi- 
dae, Elateridae, Tillidae, Meloidae, Tenebrionidae, 
Pyrochroidue, Dermestidae, Cerambycidae, with 
Donacia, Heterocerus, &c.; see L. Dufour, 
Suckow, loc. cit. and Brandt, Mediz. Zool. II. 
Taf. XVII. XIX. This glandular apparatus is 
specially developed with Hydrophilus piceus, 
where, of the four pairs, one is distinguished for its 
length and thickness, and is composed at its extrem- 
ity of numerous small. follicles; see Swammer- 
damm, Bib. der Nat. Taf. XXII. fig. 45 1. Du- 
four, loc. cit. VI. Pl. VI. fig. 7, and Suckow, loc. 
cit. Taf. X. fig. 1, 3. 
1 See Burmeister, Wandb. &c. I. p. 227, Taf. 
XIII. 
2 As yet, these differences in form of the external 
male organs have been of little service to entomolo- 
gists in the distinction of species, although, had 
they been well understood, the formation of many 
bad species might have been prevented. They 
prevent allied species from producing bastards by 
adulterous connections, for the hard parts of the 
male correspond so exactly with those of the female, 
that the organs of one species cannot fit those of 
another. ZL. Dufour has, therefore, properly 
termed these copulatory organs as “la garantie 
de la conservation des types, et la sauvegarde 
de la légitemité de Uespéce.” 
3 This horny apparatus, from its large and often 
tumid lateral valves is quite prominent with the 
Dolichopidae, Empidae, with Asi/us, Laphria, 
Ctenophora, Nematocera, and other Tipulidae. 
See Sch ed, Beitr. zur E 1. Taf. I.-ITI. 
(Tipula). 
4 With the Panorpidae, these copulatory organs 
are changed into very large pincers; while with 
Psyche, the very long penis is protractile like the 
tubes uf a telescope, thus enabling these butterflies 
to copulate with their females which remain cone 
cealed in sucks, 
