356 Prof. E. Claparede on the Structure of the Annelida. 



discovery. He ought, I think, to have cited in the first place 

 the name of M. Hering, who is nowhere mentioned in the 

 ' Histoire Naturelle des Anneles.' However this may be, the 

 honourable Academician reproaches us, and especially myself, 

 with having said a great deal and drawn but little. I do not 

 think I deserve this reproach, as the segmental organs of 

 the Annelida, being very simple modifications of a very con- 

 stant type, may be easily desci'ibed without having recourse 

 to the pencil. Moreover, without speaking of the works 

 of M. Ehlers and myself, M. de Quatrefages might have 

 found segmental organs described and figured by M. Kefer- 

 stein, in Cirratulus filiformis (Keferst.), Capitella {Notomastus) 

 rubicunda (Kef.), Terebella gelaiinosa (Kef.), and Sijllis ohlonga 

 (Kef.) . Nevertheless, in order to satisfy the desire expressed by 

 M. de Quatrefages, figures relating to the segmental organs of 

 various Annelida will be found in the plates following this 

 memoir. 



It is, moreover, indubitable that there are Annelida destitute 

 of segmental organs, or at least in which these organs are re- 

 duced to simple apertures in the wall of the body. 



Nervous System, 



It is undoubtedly to M. de Quatrefages and M. Leydig 

 that we owe the finest investigations upon the nervous system 

 of the Annelida ; the former has occupied himself especially 

 with the exterior form of this system, and the latter with its 

 histology. The ' Histoire Naturelle des Anneles ' omits all 

 historical details upon this subject ; but if we go back to the 

 earlier works of the author, we shall find a concise and well- 

 executed summary of the previous researches*. It is more to 

 be regretted that it takes no notice of the labours of recent 

 histologists, MM. Leydig, Mettenheimer, &c. On the whole 

 we find in the portions of this memoir relating to the nervous 

 system a confirmation of the investigations of M. de Quatrefages. 

 On some points, however, I must differ from him. Lastly, there 

 is an important chapter upon which I have hardly a right to pro- 

 nounce judgment. In nearly all the families M. de Quatrefages 

 has been fortunate enough to detect a stomato-gastric nervous 



* See " Etudes sur les types inferieurs de rerabranchement des 

 Anneles. Memoire sur le systeme nerveux des Annelides/' Ann. Sci. 

 Nat. tome xiv. p. 332, 1850. No doubt this summary presents some 

 gaps. We regret especially to see no mention in it of the investigations 

 of G. R. Trevirauus upon the nervous system of Aphrodita ; for this 

 observer was already well acquainted not only with the ventral chain and 

 the nerves which originate from it, but also with the ganglia of rein- 

 forcement at the base of the feet. 



