POLYCH^TA BENHAM. 75 



One of these had been cleared and mounted in balsam it measures 4.7 mm., and 

 consists of " head " and 26 chsetigerous segments. It had apparently been fixed in 

 osmic acid, for many of the granules in the body wall and in the inteiior of the body 

 are blackened (fig. 82). 



The other, when it reached me in alcohoi, was flattened as if it had been studied 

 under a cover slip ; this I stained in alum carmine its length is 3-5 mm. It is rather 

 difficult to be sure of the number of chaBtal bundles, for it is flattened asymmetrically, 

 lying on one side with the ventral surface upwards, one series of parapods ( of the left 

 side) being along one edge for about half the length, the rest below the margin, the other 

 series lying along the middle of the preparation they are not easy to see except under a 

 high power. 



I believe, however, that there are 25 or 26 pairs of parapods. The body is not other- 

 wise segmented ; there are no external furrows, and internally there are several large ova 

 which are without that regular arrangement they would have were any septa present. 



The ventral surface is flat, the dorsal much arched. As the animal lies the distance 

 from one set of parapods to that on the other side is about three times the width of the 

 ventral surface. 



The whole surface of the animal is densely covered with crowded papilla; (hence 

 the specific nan e). These are well seen in profile along the edge, and each is a mass of 

 cellular substance enclosed in a continuation of the cuticle of the body. Over the 

 body the cuticle is unusually thick, but it becomes rather thinner as it rises up to form 

 the wall of the papilla. Within are a few nuclei stained greenish-brown (in the osmic) 

 and some pale carmine-stained protoplasm and threads. At the base the cuticle is 

 pierced by a small aperture allowing a continuity between the contents and the substance 

 of the body wall (fig. 87). 



The two ends of the animal are very similar : the anterior end does not present 

 any differentiated prostomium ; no lobe is marked off from the first body segment. 

 At a little distance from the end is a pair of eyes ; at least, so I interpret the structures. 

 In the unstiined cleared specimen there is a pair of sharply-defined oval vesicles 

 surrounded by a firm membrane, pale brownish in colour, but without visible contents 

 (fig. 83). In the stained specimen black pigment spots occupy a corresponding position. 



I cannot detect any tentacles, although 1 examined both specimens under high 

 power. There are no processes, other than the papillae, visible in these flattened 

 specimens, and none of them are longer than their neighbours. The anterior end, like 

 the rest of the body, is densely covered with these papillae. 



There is no distinct peristomium ; the first bundle of bristles lies about midway 

 between the eyes and the entrance to the pharynx, which must be a short distance 

 behind the mouth, whose position I am unable to determine. The structure of the head 

 is, in fact, just as Ehlers has described it for S. parvum, except that in that species 

 he finds distinct tentacles, 



