360 OWENIA FTISIFQRMIS. 



considerable size, which hang loosely in the body-cavity— a pair to each of the first and 

 second anterior segments, 1 and the first four posterior segments. Each is attached to the 

 body-wall by one extremity, which forms a duct opening between the end of the torus and 

 the bundle of bristles of the segment to which it pertains (Watson). These secrete a 

 thick viscous liquid, containing fine colourless threads, used in the formation of the inner 

 lining of its tube. De St. Joseph found a minute distome fixed to one of the glands. 



The septa, as pointed out by Grilson, have two valves, viz. a simple slit or flap-valve 

 dorsally, opening forward like a door, and a sphincter valve ventrally. Watson noticed 

 that the forward current passed through the dorsal valves, and the backward current of 

 coelomic fluid through the ventral. These valves are specially powerful in the septum 

 separating the anterior from the posterior region. 



The next three segments are comparatively long, each being about twice the length 

 of the anterior region of three segments. The first of these (the fourth bristled segment) 

 has two dorsal bristle-tufts immediately behind its anterior border and two tori for 

 hooks ventrally in the same line as the bristle-tufts. Two glandular bands pass dorso- 

 lateral^ from the bristle-tufts to those of the succeeding segment, curving inward as they 

 approach the bristles. The ventral surface is marked only by the grooved median band. 

 The next two segments follow the same arrangement dorsally and ventrally. Watson 

 describes an olive-green, zig-zag canal as running almost from end to end of the second 

 segment of the posterior region, and this is the nephridium of Grilson, for it has an 

 internal funnel-shaped opening, and a slit-like aperture externally. He found, however, 

 that it does not transmit the genital products as Grilson supposed. The seventh bristled 

 segment is shorter, but it also presents the same glandular bands dorsally, the dorsal 

 bristles in front of this segment and at its rear being nearer each other, and the posterior 

 pair in front of the tori. The following or eighth bristled segment inaugurates a change, 

 for it has no dorsal glandular bands, and posteriorly it is separated from the next segment 

 by a deep furrow, in front of which are the tori, the edges of which are dorsal, and the 

 bristles, like those in front, are near each other. Moreover, a couple of dimples occur 

 anteriorly on each side of the middle line. Further, if it be held that the anterior 

 segments have their tori and bristles in front, then this segment (eighth) has a double 

 series, those in rear being in front of the segment-junction, and the bristles slant upward 

 and forward. The following segments bear the dorsal bristles on the outer edge and 

 widely apart from each other, and the tori are ventral in position. The direction of the 

 bristle-tufts after the eleventh abdominal segment is usually in the preparations more or 

 less transverse. Moreover, these posterior bristles — even to the tip of the tail— are lateral 

 in position. The segments gradually diminish in antero-posterior diameter toward the 

 tail, which is terminated by a comparatively large anus with a papillose margin, a few 

 of the minute segments adjoining it apparently having no bristles. 



The bristles throughout have the same structure, and are slightly pinnate at the 

 extremity (Watson), those in the posterior segments being fewer in number and 

 proportionally longer and more slender. The tori form characteristic bands of a 

 multitude of minute hooks (Plate OX, figs. 9 a and 9/;) forming a rasp-like series, each 

 individual with two well-marked hooks, the posterior curve of which is prominent at the 



1 Gilson indicates a rudimentary gland in the third anterior segment. It is sometimes absent. 



