§ 355. THE INSECTA. 463 



abdomen. <5> Tliis penis is composed of three articles with Aeschma, Lihel- 

 lula, and Gojnphus ; but of one only with Caloptenjx, and Agrion, with 

 which it is not directly adherent to the seminal vesicle. The male Libel- 

 lulidae are obliged, before copulation, to fill their veskula 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 oriiice in contact with the copuUi- 

 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 At rest, these organs are entirely withdrawn into the abdum- 

 inal cavity, but can be widely protruded out of it by means of a vei-y remark- 

 able muscular apparatus.*'" With the male individuals of Bermestes, there 

 is a median orifice 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- 

 appearance of the gerniinative vesicle,*^' there is formed, from a superficial 

 and partial segmentation, a round or oblong-oval blastodcrma, whose 

 hyaline aspect contrasts with that of the rest of the vitellus.*-' This blas- 



5 For the copulatory orfcans of the Libellulidae, 1 The germiaative vesicle is never observer! in 

 see Rathh^, De Libellar. partiljus genital., and my eggs that have been layed ; it has disappeared 

 researches in Germar''s Zeitsch. II. p. 421. even in those still in the oviduct ; this disappear- 



6 The act of copulation of the Liliellulidae has ance would not appear, therefore, to depend upon 

 been represented by Swamtnerdanmi, Bib. der the act of fecundation. 



Nat. Tat'. XII. fig. 3 ; Reaumur, Jlem. &c. VI. 2 The first phases of the development of Insecta 



PI. XL. XLI. ; and Roesel, Inseotenbelust. Th. have been studied by Herold (Disquisit. de Anim. 



II. Insect, aquat. Class. II. Tab. X. vertebr. carent. in ovo format. 1835-38) with 



^ The different forms of these piniers have been Spinx liffustri and Musca vomit oria; and by 



figured in Charpentier, Idorae Entomol. Tab. I., A 6//iA-er (Observ. de prima Insect, genesi, 18i2, or 



and Selijs Lon^champs, Monogr. des Libellul. Ann. d. Sc. Nat. XX. ISiS, PI. X.-Xll.) with 



d'Europe, PI. I.-IV. Chironomus, Simnlia, and Donacia. 



8 See Strau.i, Consider. &c. PI. III. V. The ulterior phases have been traced by Rathke 



'J See my observations in the Entomol. Zeitung. {Meckel's Arch. 1832, p. 371, Taf. IV. and Mut- 



1840, p. 137, and BrulU, Ana. d. 1. Sue. Eutom. Le.r's Arch. 1844, p. 27, Taf. II.) with Blatta 



VII. 1838, p. LIII. The golden-colored tuft orienlaU.i and Grytlotalpa vulgaris ; and by 



of hairs situated at the base of the abdomen Nicolet (Recherch. &c. p. IS, PI. I.) with the 



with the males of Blaps, does not correspond to Poduridae.* 

 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 conditions of formation belonging to the different 



numerous researches upon the embryology of the groups, and the observation of the details of de- 



Insecta made within a few years, have added any velopmeut of different internal and external organs. 



new phases to the general type of development of Those anomalies of development and reproduction, 



these animals as brought out by the earlier inves- which continued research shows to be far from un- 



tigators. The type of development with the Arth- common with the Insecta, will ultimately be found, 



ropoda is essentially the same in all of the classes probably, referable all to the phenomena, we have 



of this section. What late observers have done, discussed below, of the Aphidldae. — Ed. 

 therefore, is the tracing of some of the secondary 



