376 SCALISETOSUS COMMUNIS. 



debris from the haddock-hooks on the 16th September, 1889. The injured specimen had 

 nine or ten bristled feet. The head showed two broad lobes in front, with a deep median 

 notch. Only the ceratophore of the median tentacle remained. The lateral tentacles 

 formed two short subulate organs. The palpi were fairly developed, with tapering tips. 

 The tentacular cirri had long slender tips, readily distinguished from those of allied 

 forms, and all these organs were smooth. A pair of black eyes— very widely separated— 

 were situated at the posterior part of the head. The teeth of the proboscis were clearly 

 visible as four hollow, pointed chitinous processes, with a small spur near the base, and 

 with long homy limbs for the attachment of muscles. The dorsal bristles were recognised 

 by their characteristic scalariform structure, from three to six or seven rows of spines being 

 present. They were more slender than in the adult, and tapered to a delicate tip. The 

 ventral bristles had the prominent) basal spur, and the long slightly curved and more 

 finely spinous tip. They projected considerably on each side, as became the nectochaete 

 stage. 



The Aphrodita velox of Dalyell (1853) is in all probability this form, its translucency, 

 irritability, and general aspect being characteristic. His example was scarcely half an 

 inch long. 



Kinberg's Hermadion (185 7) had the following characters :— Head broader posteriorly. 

 Posterior eyes distant from the anterior. Elytra fifteen, not covering the posterior 

 part of the body. Inferior bristles serrate below the apex. Foot elongate. There is 

 little that is diagnostic in this, and certainly the present genus requires a more precise 

 definition. His species were quite different from the British, and came from the Straits 

 of Magellan. 



Ehlers (1864) gave a long and careful description of the species from Quarneo in the 

 Adriatic, detailing the essential characters, though his figures of the bristles and scales 

 needed improvement. His specimens were small, only from 7 to 9 mm., and of twenty- 

 two segments. The ciliated processes on the dorsum of the foot he considered the 

 external part of the segmental organs ; and as his examples bore reproductive elements 

 (summer), he was the more certain of the function of these organs. Haswell and Bourne 

 have both pointed out, in other species, the true segmental organs, which are on the 

 ventral surface. Ehlers thought the species had relationship with Kinberg's genus 

 Hermadion. 



Olaparede (1868) published a fairly accurate account of this species from Naples, 

 pointing out the palpocils on the cilia of the cirri, and the ciliated cushions on the dorsum 

 of the feet. He also describes the remarkable facility with which the distribution of the 

 nerves can be followed. Its irritability struck him, and it cast off both scales and cirri. 

 He, like Ehlers, placed it under Kinberg's genus Hermadion mainly because the scales 

 only overlapped in the anterior region of the body. 



In his supplement to the 'Annelids of Naples ' (1870), the same author recognised 

 that his Hermadion fragile was Delle Chiaje's Lysidice communis, which that author 

 had represented with only the anterior pair of scales, and to which his artist had 

 added a pair of cirri on every segment — of which the figure shows no less than 

 about sixty. In this communication Olaparede describes the segmental papilla 

 at the inner border of the foot ventrally, and shows a membrane investing the 



