and their Position in the System of the Annelida. 401 



the Notomasti are distinguished from the Capitella. Nay, it 

 may even appear questionable whether Dasybranchus and Noto- 

 mastus are to be generically separated ; for if it be confirmed 

 that some Glycera are destitute of branchiae, and the presence 

 of these organs here furnishes no generic character, the same 

 thing might be applied to Dasybranchus: In both, the superior 

 combs of uncini at the commencement of the posterior division 

 of the body are brought quite upon the back, and are much 

 narrower than the inferior ones, by which Notomastus acquires 

 a greater similarity to Dasybranchus than to Capitella-, it is also 

 only in these two that a proboscis (protrusible pharynx) is ob- 

 served ; nevertheless, from what I have seen in the anatomy of 

 a Capitella, I must assert that in them also the commencement 

 of the alimentary canal can be turned out. The appareil secre- 

 taire renal, which D'Udekem describes in Capitella, I have 

 hitherto been unable to find in Dasybranchus and Notomastus ; 

 but the specimens examined by me were not in the best possible 

 condition ; and it would be very important, in future investiga- 

 tions, to pay attention to this point. 



The large curved bristles which appear in a transverse series 

 before and behind the genital orifice of the male, and have their 

 apices directed towards each other, have hitherto only been ob- 

 served in the Capitella-, they may perhaps be regarded as a 

 transformation of the combs of small bordered uncini, which are 

 wanting on the segments in question. But are we acquainted 

 with the males of Dasybranchus and Notomastus? Perhaps they 

 may possess a similar character. At any rate, these organs 

 remind us of the two strong hook-like bristles (spicula) which 

 are so striking on the ventral surface of the Thalassemia, Echiuri, 

 and Bonellia, and are likewise placed before the paired and me- 

 dian genital orifices of these animals. In the Echiuri a posterior 

 pair is also concealed within the skin*. The more distinct se- 

 paration or partial amalgamation of the genera Dasybranchus, 

 Notomastus, and Capitella must be left for further and more 

 accurate investigations; but I think I have demonstrated that 

 these three genera stand in a close relationship, and must be 

 referred to one family, the Capitellacea, which, in my opinion, 

 are related to the Arenicola in the same way as the Gephyrei 

 without vessels and with a highly developed fluid in the somatic 

 cavity to the Gephyrei with vessels. The development of the 

 Capitella, upon which we have such interesting information from 

 VanBeneden, and which so much resembles thatof the Arenicola f, 

 the form of the ova, and the separation of the sexes, all agree 



* M. Miiller, Obs. Anat. de Verm, quibusd. marinis, 18-13, p. 11. 

 "t; Schultze, Ueber die Entwickelung von Arenicola piscatorum, Halle, 

 1856 j transl. in Ann. Nat. Hist. ser. 2. vol. xviii. pp. 105 et seq. 



