(Inll-priHliniiuj AiHjalUalida. ^J45 



living in plants arc oviparous*, and that tliey have their <^enital 

 apertures in the vicinity of the posterior extremity of the bo<ly. 

 This is precisely the case in the Anguillula of the milfoil ; it 

 is oviparous, and the genital apertures of both sexes are more 

 or less near the caudal extremity. Their distance from the 

 latter must be regarded, in the present state of our knowledge 

 of these miimals, as one of the best of the few specific characters. 

 The male has a somewhat curved linguliform penis, rapidly 

 attenuated from a broad base ; this can be pushed forth from 

 the anus, which surrounds it like a sheath, and ojjcns obliquely 

 backwards and outwards. The cleft-like anal orifice, which is 

 placed transversely to the longitudinal axis of the body, lias a 

 slightly prominent margin, and is situated at a distance of 

 one sixteenth or one seventeenth of the total length of the 

 body from the end of the tail. Immediately behind the anus 

 the transverse diameter of the body of the male diminishes 

 considerably ; it tapers off quickly to a ])oint, which in the 

 adult male is always bent almost angularly in a direction 

 away from the anal aperture. In most cases the penis was 

 retracted within the anus, so that the margins of the latter 

 closed together ; only in one individual did the aj^ex of the 

 penis project from the anal cleft, when it was distinctly seen 

 to be a little broader than thick, /. e. tongue-shaped. The 

 magnifying-power with wiiich I worked did not enable me 

 to see distinctly the two npicula and accessory parts, of which 

 the penis of the Anguillulidiii consists. 



A short distance in front of the male genital aperture, about 

 the beginning of the last twelfth of the body, there originates 

 a very delicate, perfectly transparent membrane, which extends 

 over the above-mentioned genitalia to the hinder extremity, 

 and is attached to the sides of the body. This membrane is 

 usually tightly stretched, only appearing slightly folded trans- 

 versely in dried individuals. When tlie male is laid exactly on 

 his back, the membrane described is frequently seen to project 

 a little laterally beyond the margin of the body ; but in most 

 instances this is not the case. 



* As Linne was already aware (see uote §, p. 34:J), the Auguillulidse 

 are sometimes oviparous, sometimes viviparous. The>-e different modes 

 of reproduction even occur in the same species ; for Goeze repoi-t3 

 (•' Mikrosk. Erfahrungen Uber die E-sigaale," iu the ' Xaturforscher,' 

 Stiick i. 1774, p. 34) that the AngiiilluUe of vinepr bear living- young 

 after the manner of the Aphides, from July until autumn, and in the 

 autumn lay eggs which surnve the winter. Nay, even the same indi- 

 vidual may be both oviparous and viviparous; for Claus states (Zeitschi-. 

 fiir wiss. Zool. IM. xii. 18f)3, p. .'$04) that his oviparous A. hrevispina is 

 identical with Grube's A. >niicrona(a, as in this species the same female 

 produces her first brood oviparously and the later ones viviparously. 



