32-i On the Young Stages of a few Annelids. 



bachtungen. Yet notwithstanding this correction of Quatrefa- 

 ges by Claparede* in bis review of the System proposed by the 

 former, and the accurate description given by him (Claparede) 

 in Miiller's Archivf of Poly dor a cornuta, we find him associating 

 with the genus Polydora in his embryology of Leucodora 

 ciliata, a genus which is certainly not Polydora, as he himself 

 has limited it, but may be a species of Spio or Nerine, or per- 

 haps what Quatrefages understands by Leucodora. At any rate 

 it is self-evident from the following embryology of a species of 

 true Polydora, and of a species of what Claparede has called 

 Leucodora in his Beobachtungen, that we have in each deve- 

 loped at a very early period, genuine characters which refer un- 

 doubtedly one form to Polydora, and the other to a different 

 genus (Leucodora Clap, non Johnst.), probably Nerine Johnst. 

 Thus proving the assertion of Quatrefages^: of the generic differ- 

 ence between Leucodora Clap, and Polydora Bosc. And yet 

 in spite of this generic difference, Claparede was correct in 

 maintaining the identity of Leucodora Johnst. and Polydora 

 J3osc, as can be readily seen on examining the descriptions and 

 figures of Bosc,§ Johnston, Oersted,! Leuckart,^[ Claparede, and 

 Keferstein.* 2 The error arises from Clapaiede's mistaking for 

 the young of Polydora the young Annelids figured by him on 

 Plate vii. of his Beobachtungen, which having no trace of the 

 characteristic fifth segment, belong therefore not to Polydora 



* Claparede A. R. E. ; in Bibliotheque uiiiverselle de Geneve. Avril. 1865. 



f Claparede A. R. E. ; Ueber Polydora cornuta Bone ; in Archiv fur Anat. u. 

 Pbys. 1861. p. 542. 



\ Quatkefages A. de. Note sur la classification des Annelides ; et reponse aux 

 observations de M. Claparede: in Ann. des Sc. Nat. 5me Ser. iii. 1865. 



§ Bosc ; Histoire Naturelle des Vers. 



|| Oersted A. S. Zur Classification der Anneliden; in Archiv fur Naturg. 

 1844. i. p. 105. 



^[ Leuckart R. Zur Kenntniss der Fauna von Island ; in Archiv f. Naturg. 

 1849. l.p. 200. 



* 2 Keferstein W. Untersuchungen ueber niedere Seethiere; in Zeits. f. Wiss. 

 Zool. xii. p. 116. Juni, 1862. 



