EUSYLLIS TUBIFEX. 175 



ceratophore, or basal process, is ciliated, and the large and powerful cilia extend to the 

 setigerous region. 



The proboscis (Plate LIX, fig. 11), which extends to the sixth segment, has a 

 denticulated edge, though more than a third of the circumference is only minutely 

 crenated; and it is furnished with a small pyramidal tooth situated on the smoother part 

 of the edge. The sides of the organ are thrown into prominent wrinkles. Several elon- 

 gated papillse occur in front of the anterior edge of the proboscis — some directed forward, 

 others backward (the soft ring under compression). The proventriculus is studded with 

 minutely granular dots, and stretches to the thirteenth segment. This organ would seem 

 to act as a compressor, for its two halves occasionally move against each other. The 

 glandular intestine is rendered moniliform by the septa, and terminates posteriorly in a 

 ciliated rectum. Occasionally ciliary action is observed just behind the proventriculus 

 and apparently extending into the lateral casca as well as along the gut. 



The foot (Plate LXX, fig. 9) presents dorsally the tapering cirrus which has more 

 distinct crenations anteriorly than posteriorly. After an interval is the somewhat conical 

 setigerous region, with the tips of the spines pointing at the upper angle. The bristles 

 (Plate LXXIX, fig. 1) form a fan-shaped series, with the convexity of the curve 

 directed dorsally, and the curvature increasing from the dorsal to the ventral edge of the 

 series. The bevelled distal end of the shaft is minutely spinous. The terminal piece is 

 comparatively short and bifid, with the hooks directed upward so that they would be useful 

 to the annelid in clinging to its tube or other surface. There is little difference between 

 the anterior and the posterior bristles. The ventral edge of the fan of bristles has more 

 slender bristles, but the terminal pieces are longer than the superior. The ventral cirrus 

 is ovate with a bluntly-conical tip which does not extend so far outward as the setigerous 

 region. In the posterior feet this lobe is smaller and more pointed. A well-developed 

 tuft of long cilia occurs between the dorsal cirrus and the setigerous lobe, and another on 

 the dorsal edge of the latter. 



Reproduction. — This species perhaps sometimes develops directly, since comparatively 

 large ova occur in the ordinary forms, yet in these, between the dorsal cirrus and the 

 setigerous lobe of the foot, indications of a spine are observed, though none of the natatory 

 bristles are developed. 



Ovigerous buds with long natatory bristles supported by a spine also occur, and the 

 ordinary bristles are somewhat longer both in shaft and terminal piece. Such buds are 

 found on the blades of the tangles in April. 



Habits. — They rapidly secrete a translucent tube in confinement, and thus protect 

 themselves. If incautiously interfered with their bodies are ruptured, and the anterior 

 end wriggles out of the tube. 



On being irritated with the forceps, the annelid emits a fine green light from the 

 ventral surface of each foot and as if from many minute pores at the area. It flashes 

 along both sides posterior to the point of irritation, and fades, a faint trace remaining for 

 a few seconds. On severe irritation it remains luminous behind the injured point for 

 nearly half a minute, and the surface of granular light on each segment is larger than 

 usual, and in a few instances is connected across the ventral surface by a few granular 

 phosphorescent points. For some time it was sufficient to shake the vessel to cause a 



