and their Position in the System of the Annelida. 399 



the generative organs. As something new added, we have the 

 large curved bristles at the orifice of the testis, the arrangement 

 of the bristles in lateral rows, the separate sexes, the different 

 structure of the ova, and the metamorphosis of the young ; but 

 it must certainly be admitted that we do not know the young 

 states of the marine forms of the Agemmes; and whether these 

 pass through a metamorphosis it is as impossible to predict as 

 it was to suppose, in the case of the Lobster, that it follows a 

 different course of development from that of its nearest ally the 

 river crayfish. 



Turning to the Polychsetse, would it be more difficult to find 

 among them forms with which the Capitellce could be arranged ? 

 I admit that, however I was determined by Oersted's first com- 

 munications, and before I had myself seen these animals, to 

 follow him and place them among the Naides, I afterwards hesi- 

 tated about leaving them in this position ; and at the first sight 

 of a large spirit specimen I thought no more either of the Naides 

 or of other Oligochsetse. In this specimen the segments were 

 proportionally considerably longer, in the anterior portion of the 

 body, furnished only with setae, half as long, in the posterior 

 portion, bearing uncini, one and a half times as long as broad ; 

 moreover the uncini were grouped in regular combs, and in- 

 serted in distinct ridges. This had also struck Claparede, and 

 appeared to him so important that he approximated the Capi- 

 tellce to the Maldanice*, which, indeed, stand near the Lumbri- 

 cinae, according to the views of Cuvier and Milne-Edwards, but 

 were placed by Savigny and Lamarck, with whom I agreed, 

 near the Arenicolce and Terebellce. For my own part, I was 

 more vividly reminded of the genus Dasybranchus (olim Dasy- 

 mallus-\) and of Notomastus%. If Van Beneden only assumes 

 that the evolution of the organization in the Lumbricinae may 

 retrograde, and the vascular system disappear, this decidedly 

 takes place among the Polychaetae. As regards the respiratory 

 organs, in the first place, we find, in the genus Eunice, together 

 with species with greatly developed branchiae (such as E.gigantea 

 and E. Harassii), others with very rudimentary branchiae (such 

 as E. siciliensis) , and, in the genus Lumbriconereis (in the wide 

 sense), species with very simple branchiae, and others with none 

 at all. Quatrefages§ has already shown by examples how, be- 

 sides the Polychaetae with a vascular system ramifying every- 

 where, others occur in which it is only partially developed, and 

 others, again, in which it is entirely wanting ; and in the latter 



* Memoires de la Soc. de Phys. et d'Hist. Nat. de Geneve, 1861, p. 110. 

 + Archiv fur Naturgeschichte, 1846, p. 166, tab. 5. fig. 3. 

 X Sars, Fauna litt. Norveg. ii. p. 11. tab. 2. figs. 8-17. 

 § Aim. Sc. Nat. se'r. 3, Zodl. xiv. pp. 268, 294, 296. 



