LEPIDONOTUS SQUAMATUS. 277 



bosses project as blunt points from the surface in profile. The scales (Plate XXXII, 

 fig. 1) increase in size posteriorly, the general shape being ovoid, though they are wider 

 at the ciliated posterior border. The under surface is smooth and iridescent, and shows 

 the pear-shaped scar for the attachment of the pedicle. In some, however, the surface 

 presents the ends of fibres torn from the pedicle, and this sufficiently explains why 

 some are readily removed, and others require separation with a knife. All the scales 

 considerably overlap each other, and cover the dorsum entirely. The simple filiform 

 cilia which occur on the edge appear to preserve the same relative length from the first 

 to the last, and they are often coated with a muddy deposit, and have various micro- 

 scopic growths. So far as can be observed, these cilia are simple and nearly cylindrical 

 processes with a smoothly-rounded tip, and a median streak, as if from an axis of 

 differentiated tissue. Under the action of potash the scale becomes coarsely granular or 

 areolar, the areas of the bosses or blunt spines being characterised by a more regular 

 arrangement of granular cells. 



In young examples, barely 3 mm. in length, the scales have a few large tubercles, 

 and the cilia are hirsute, with grains of various kinds, besides being proportionally larger 

 than in the adult. De Saint- Joseph found that in a small example, 5 mm. long, the 

 scales were covered with Gramrnatophora marina. 



In general structure the scales have externally a more or less chitinised cuticular 

 layer, with a cellular (columnar) coat beneath, a fibrous stroma passing between the 

 dorsal and ventral layers, and finely-branched nerves, from the ganglionic mass at the 

 scale tubercle, terminating in end-organs. The external surface has various chitinous 

 tubercles or processes, and the edge has cilia. 



The chitinous tubercles and spines are placed in the thick cuticular layer, and the 

 larger are hollow in the centre, and the surface is roughened with small processes so that 

 they look honeycombed. This is due to the minutely nodular condition on the surface, 

 and not to scales, as Baron de Saint- Joseph l states. When the dark brownish (Algoid ?) 

 coating begins to cover their surface, the " bosses " present a reticulated appearance, 

 since the parasitic growth first invades the hollows between the minute tubercles, 

 Pigment occurs in the cellular layer beneath. The scar has a complex series of muscles, 

 some of which pass into the hollow of the organ. The majority of the muscular fibres 

 are fixed to the scale-tubercle. As Prof. Haswell 3 says, they serve in the Polynoidse for 

 protection, for the production of phosphorescence, for sensation, and in certain forms 

 for incubation. 



The scales readily separate in ripe examples, and the under surface is as finely 

 iridescent as in Kaliotis. Captured specimens reproduce their scales. Thus in a month 

 they reach about a third the size of the original organs, but are pale, and their translucent 

 condition shows that the tips of the papillas are minutely nodular. 



Many parasitic structures occur on the scales, but none more beautiful than 

 Carchesium, the long tufts of which resemble, under the lens, miniature zoophytes. 



Occasionally examples occur with a deep orange coating on the under surface of 

 the scales and the dorsum of the body. In structure it is minutely granular, as in the 

 darker (blackish) coating on the bristles and other organs. 



1 ' Ann. des Sc. Nat./ 8th ser., v, p. 231. 2 < Ann. Nat. Hist./ 8th ser., x, p. 241, 1882. 



