220 



ANNELIDA. 



J. 



observed in the anterior part of the body of Arenicola five grey 

 vesicles resembling the ovaria of the earthworm ; and he was led 

 to conclude, in conformity with the Figt 94 



then generally received opinion, that 

 the ova escaped from these vesicles 

 into the cellular structure between 

 the intestine and the walls of the 

 body. It is, however, probable that the 

 granular bodies {Jig. 94, m, m) usu- 

 ally found in that situation are para- 

 sitical Entozoa, as those of the earth- 

 worm have been proved to be. ; { 



In .the Nereis, Delle Chiaje de- 

 scribes the ovaria as two long and ex- ; 

 trernely delicate caeca, occupying the , 

 posterior half of the visceral cavity, ( 

 and offering various constrictions and " 

 dilatations in their course ; these 

 caeca terminated by distinct apertures 

 in the neighbourhood of the anus, 

 and when gravid were found to be 

 filled with granular ova of a greenish 

 colour. 



(264.) In one species of Nereis (N. 

 prolifera), Miiller* observed repro- 

 duction to take place by spontaneous 

 division ; a mode of propagation which, 

 although common among the Naidce, 

 had not previously been seen in any 

 of the Dorsibranchiate families. The 

 process of division is represented in 

 the appended figure (fig. 95); the 

 hinder part of the body, including 

 about seventeen segments, is seen to 

 be gradually separated from the ante- 

 rior or larger portion, and, moreover, 

 at the point of separation a new head 

 with eyes and tentacular cirri is dis- 

 tinctly formed. " In one case," says 



* Ohtho Fred. Mii.Mer, Zoologia Danica, pi. lii. fig. 6, fol. 1788. 



