§ 355. THE INSECTA, 463 



abdomen.'^' This penis is oomposed of three articles with Aeschjia, Libel- 

 hila, and Gomphus ; but of one only with Calopter^jx, and Agrion, with 

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

 lulidae are obliged, before copulation, to fill their vesicula seminalls, 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 At rest, these organs are entirely withdrawn into the abdom- 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 remai'k- 

 able muscular apparatus.''^* With the male individuals o? iJermestes, there 

 is a median orifice on the third and fourth abdominal segments, from which 

 projects a brush of stifi' 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 

 n^anner as with most of the other Arthropoda. After the unusually early dis- 

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

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

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



5 For the copulatory organs of the Libellulidae, 1 The germinative vesicle is never observed in 

 see Rathke, De Libellar. partibiis genital., and my eggs that have been layed ; it lias disappeared 

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



6 The act of cojiulation of the Libellulidae has ance would not appear, therefore, to depend upon 

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



Nat. Taf. XII. fig. 3 ; Reaumur, Mem. &c. VI. '-i The first phases of the development of Insecta 



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



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



<■ The different forms of these pin::ers have been Spinx ligustrt and Miisca vomit or ia ; and by 



figured in Charpentier, Horae Entomol. Tab. I., KöUiker (Observ. de prima Insect, geuesi, 1842, or 



and Selys Lon^c/iamps, Monogr. des Libellul. Ann. d. Sc. Nat. XX. 1843, PI. X.-Xll.) with 



d'Euroiie, PI. I.-IV. Chironomus, Siynulia, and üoriacia. 



S See Straus, Consider. &c. PI. III. V. The ulterior phases have been traced by Rathke 



'■) See my observations in the Entomol. Zeitung. {MeckeVs Arch. 1832, p. 371, Taf. IV. and Mal- 



1840, p. 137, and Brülle, Ann. d. 1. Soc. Eiitom. le.r's Arch. 1844, p. 27, Taf. 11.") with Blatta 



VII. 1838, p. LIII. The golden-colored tuft orientalis and Gryllotalpa vulgaris ; and by 



of hairs situated at the base of the abdomen Nicolet (Recherch. A:o. p. IS, PI. I.) with the 



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

 that of Der7nestes, because it is only external and 

 does not project mto 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 ad<led any velopment 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, 



jopoda 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 Aphididae. — Ed. 

 therefore, is the tracing of some of the secondary 



