§$ 355. 463 
abdomen. This penis is composed of three articles with Aeschma, Lilel- 
éula, and Gomphus ; but of one only with Calopteryz, and Agrion, with’ 
which it is not directly adherent to the seminal vesicle. The male Libel- 
lulidae are obliged, before copulation, to fill their vesicala seminalis, which 
is situated at the base of the abdomen. This they accomplish by bending 
the posterior extremity of the abdomen, so as to meet and empty the semen 
into this vesicle. They then seize the female by the neck, by means of their 
anal pincers, and she places her genital orifice in contact with the copula- 
tory apparatus of the male. These anal pincers of the males have very 
distinct specific characteristics, while the females, on their part, have, in 
the separate species, equally specific sculptured markings on the protho- 
rax. 
With the Coleoptera, the copulatory organs consist of a more or less 
horny sheath enveloped by a membranous prepuce, and containing a 
broadly-flattened penis which consists of a canal supported by two lateral 
horny ridges. At rest, these organs are entirely withdrawn into the abdom- 
inal cavity, but can be widely protruded out of it by means of a very remark- 
able muscular apparatus. With the male individuals of Dermestes, there 
is a median orifite on the third and fourth abdominal segments, from which 
projects a brush of stiff bristles connected with a round muscular body situ- 
ated on the internal surface of each of these segments. This brush is un- 
-doubtedly some way connected with the act of copulation.” : 
§ 355. 
The development of the larvae of Insecta in the egg, occurs in the same 
manner as With most of the other Arthropoda. After the unusually early dis- 
appearauce of the germinative vesicle,” there is formed, from a superficial 
and partial segmentation, a round or oblong-oval blastoderma, whose 
THE INSECTA. 
hyaline aspect contrasts with that of the rest of the vitellus.” 
5 For the copulatory organs of the Libellulidae, 
see Rathicé, De Libellar. partibus genital., aud my 
researches in Germar’s Zeitsch. II. p. 421. 
6 The act of copulation of the Libellulidae has 
been represented by Swammerdamm, Bib. der 
Nat. Taf. XII. fig. 3; Réeaumur, Mém. &c. VI. 
Pl. XL. XLI.; and Roesel, Insectenbelust. Th. 
II. Insect. aquat. Class. II. Tab. X. 
7 The different forms of these pinzers have been 
figured in Charpentier, Horae Entomol. Tab. I., 
and Selys Longchamps, Monogr. des Libellul. 
d@ Europe, Pl. L-IV. 
8 See Straus, Considér. &c. Pl. IIT. V. 
9 See my cbservations in the Entomol. Zeitung. 
1840, p. 187, and Brudlé, Ann. a. 1. Soc. Entom. 
VIL. 1838, p. LIYL. The golden-colored tuft 
of hairs situated at the base of the abdomen 
with the males of Blaps, does not correspond to 
that of Dermestes, because it is only external and 
does not project into the interior of the body. 
* [ § 355, note 2.] I am not aware that the 
numerous researches upon the embryology of the 
Insecta made within a few years, have added any 
new phases to the general type of development of 
these animals as brought out by the earlier inves- 
tigators. The type of development with the Arth- 
ropoda is essentially the same in all of the classes 
vof this section. What late observers have done, 
-therefore, is the tracing of some of the secondary 
This blas- 
1 The germinative vesicle is never observed in 
eggs that have been layed; it has disappeared 
even in those still in the oviduct ; this disappear- 
ance would not appear, therefore, to depend upon 
the act of fecundation. 
2 The first phases of the development of Insecta 
have been studied by Herold (Disquisit. de Anim. 
vertebr. carent. in ovo format. 1835-38) with 
Spina ligustri and Musca vomitoria; and by 
Kélliker (Observ. de prima Insect. genesi, 1842, or 
Ann. d. Sc. Nat. XX. 1843, Pl. X.-XI11.) with 
Chironomus, Simulia, and Donacia. 
The ulterior phases have been traced by Rathké 
(Meckel’s ‘Arch. 1832, p. 371, Taf. IV. and Mul- 
ler’s Arch. 1844, p. 27, Taf. Ll.) with Blatta 
orientalis and Gryllotalpa vulgaris ; and by 
Nicolet (Recherch. &c. p. 18, Pl. I.) with the 
Poduridae.* 
conditions of formation belonging to the different 
groups, and the observation of the details of de- 
velopment of different internal and external organs. 
Those a lies of devel t and reproduction, 
which continued research shows to he far from un- 
common with the Insecta, will ultimately be found, 
probably, referable all to the phenomena, we have 
discussed below, of the Aphididae. — Ep. 
