FISSIPAROUS SPECIES OF TUBICOLAR ANNELID 345 



besides fully confirmed the fact that this mode of termination/ in the 

 singular and beautiful genus Chlorcema, which has the advantage of 

 great transparency. In this animal it is easy to observe that though 

 many of the ultimate branches of the vessels anastomose, and thus 

 give rise to a network, yet that there are also many branches of 

 no inconsiderable dimensions, which terminate in caecal extremities. 

 Such vessels may be frequently observed coming off from the 

 transverse trunk and hanging freely into the perivisceral cavity, 

 attached only by a few delicate threads of connective tissue, to the 

 parietes. It is most curious to watch the regular contractions of 

 these pendent vessels, their momentary emptying, and their subsequent 

 distention and erection by the returning wave of fluid. And in 

 considering the nature of this remarkable system of vessels, it is most 

 important to note that we have here, at any rate, no circulation, but a 

 mere backward and forward undulation. ^ 



Ciliated Canal. — A clear, longitudinal, very narrow {x'hi'^ to -gwD" 

 inch) canal (fig. 6, a) may be observed extending along the ventral 

 surface of the intestine in the middle line, from the anus, where it 

 appeared to me to open, as far as the brown dilated stomach, when it 

 either stopped or became so obscured as to be no further traceable. 

 The canal had well-marked walls with a double contour, which 

 sometimes appeared curiously broken ; and contained, set along its 

 dorsal wall, one to four longitudinal series of cilia (fig. 9). These 

 were placed at regular intervals, and worked together, as if they were 

 pulled by a common string. In young specimens there was only one 

 cilium in each row, but in the older ones I saw as many as four in 

 each transverse line. Has this enigmatical canal anything to do with 

 the ' typhlosole ' of the earthworm ? 



On the dorsal surface of the head a longitudinal canal, which 

 sometimes appears to be ciliated, was visible at b (fig. 3) ; posteriorly 

 it divided into two branches which dilated into granular cseca, 

 arranged in a kind of festoon in the first segment of the thorax. 



The coloration of this part of the body prevented me from 

 determining whether this canal opened externally or into the 

 cesophagus, and also whether it was in any way connected with the 

 ventral ciliated canal, — both of them points of much interest. 



^ This csecal termination 01 the vessels appears to reach its greatest development in the 

 Scoleid genera, Euaxes and Lumbriculus, in which a vessel arises in each segment from the 

 dorsal trunk, and shortly divides into many CEScal ramuscules. See Siebold, Vegleichende 

 Anatomie, p. 212. 



- The general contractility of the vessels of the annelids has already been pointed out by 

 De Quatrefages. Siebold doubts the existence of a regular circulation in the majority of the 

 Annelida. Oi. cit., p. 210. 



