250 Prof. M'lntosirs Notes from the 



the specially modified cells. Von Drasche * figures 'the 

 pigment only behind the collar, and his " ganglion " is small 

 and considerably in front of the collar, thus diverging from 

 the condition described here. Ziircher does not deal with 

 this region. 



In longitudinal sections a marked feature is the pennate 

 condition of the hypoderm of the anterior region — that is, 

 between the first and second dissepiments, as well as a little 

 in front of the former in certain cases ; and it appears to be 

 specially developed on the dorsum. The hypoderm is there 

 thrown into a series of ridges, which in section present a 

 streaked granular basal region terminating externally in 

 a pennate and symmetrical series of small granular cells, 

 after the manner of the barbs of a feather (PI. IX. fig. 20), 

 the breadth of the ridge varying, whilst the processes (in 

 section) increase in size from behind forward, culminating 

 in the collar with the deep groove in front (PL XI. fig. 16, and 

 PI. VIII. fig. 18). Some of the ridges, springing from the 

 continuous base, are narrow distally, so that the lateral rows 

 of cells are close on the midrib and a few are more or less 

 conical. The transition from the hypoderm of the succeeding 

 segment is by a gradual modification in the arrangement 

 of the vertical cells, which by-and-by are fan-like and then 

 pennate. This pennate condition in the preparations of 

 the hypoderm is apparently limited in distribution, since it is 

 absent in most sections both dorsally and ventrally, and Von 

 Drasche neither mentions nor figures it. Moreover, in trans- 

 verse sections, so far as observed, it is not seen, and therefore 

 may be due to the arrangement of the cells in a vertical plane 

 after preparation. An approach to this condition of the 

 hypodermic cells is observed in some longitudinal sections 

 of Myxicola, but it is less distinct than in Owenia, and is 

 probably due likewise to the effect of the preservative fluid 

 acting on a thick glandular liypoderm. The inner edge of 

 the collar has a series of minute cells along its anterior 

 border, and a fan-like series of strands and cells posteriorly, 

 whilst the tip is symmetrically pennate. The anterior curve 

 of the furrow is furnished with a special series of granular 

 pigmented cells, oc, closely arranged at the surface, and 

 which probably have the functions of eyes. They extend 

 the whole length of the collar from side to side on the 

 dorsal surface, and are partly protected bj- that fold (PI. VIII. 

 fig. 18, and PI. XI. fig. 16). 



The mucous glands {mff.) present either a characteristic 



♦ Op. cit. Tiif. i. fig. 3. 



