400 M. E. Grube on the Capitella; 



the corpuscles contained in the fluid of the somatic cavity appear 

 more numerous and more highly developed. I have hitherto 

 been unable to detect blood-vessels in the Dasybranchi, either in 

 the living state or in a spirit specimen ; their branchiae seem to 

 resemble those of the Glycerce, forming a diverticulum of the 

 somatic cavity, and taking up its fluid when they extend them- 

 selves. Just as the Glycerce stand near Polychaetae with vascular 

 branchiae, I place the Dasybranchi near the Arenicolce. The 

 Notomasti, however, agree so closely with the Dasybranchi that 

 they are essentially distinguished only by the want of branchiae. 

 In them also I have hitherto detected no blood-vessels ; but in 

 a living specimen, I distinctly saw a red fluid moving between 

 the intestine and the body-wall; its accumulation caused the 

 segments to dilate, and it consisted almost entirely of circular 

 corpuscles, 0006 line in diameter ; in a spirit specimen, which 

 wanted the posterior half, I found regular balls of apparently 

 similar corpuscles in the somatic cavity. With regard to the 

 alimentary canal, the same statements apply to both genera : 

 it commences with a rather short protrusible pharynx, surrounded 

 by pro- and re-tractor muscles, forming a proboscis ; then 

 follows a narrow tube (oesophagus or stomach ?) ; and about 

 where the change of bristles takes place this tube passes into an 

 intestine embraced by dissepiments, the anterior part of which, in 

 the spirit specimens examined, is not wider than the tube, and is 

 narrower than the posterior portion, which is usually filled with 

 much excrement. The distinctly double nervous cord, with se- 

 parated inflations, shows the greatest similarity to Lumbricus*, 

 and the arrangement of the muscular system to Arenicola. 



I must further remark that in both genera the bristles are 

 grouped on each side in two rows ; that on the anterior segments 

 only seta?, and on the remainder, which are far more numerous, 

 only uncini, occur : the former stand in very short transverse 

 rows behind narrow and low ridges; the latter in combs upon 

 ridges. It is worthy of notice that the projecting part of both 

 kinds of bristles is borderedf — a peculiarity which occurs fre- 

 quently in the setae of the Polychaetae, although very rarely in the 

 uncini (as in several genera of Euniceae, on individual segments 

 in Leucodore and Colobranchus among the Ariciadae), but which 

 I have not met with among the Oligochaetae. 



If we return again to the Capitellce, everything that I have 

 just explained is repeated, leaving out of consideration the ge- 

 nerative organs and the sexual relations in general, as to which, 

 in Dasybranchus and Notomastus, I can say nothing ; and in 

 treating of generic characters it would be difficult to state how 



* See Cuvier, Regne Animal, Annelid, pi. 1, fig. 2. 



t Van Beneden, I, c. pi. 1. figs. 8, 9; Claparede, /. c. pi. 1. fig. 12. 



