HAPMOTHOE LITXITLATA. 343 



Scales (Plate XXXII, fig. 12). — Fifteen pairs, somewhat thin, and entirely covering 

 the dorsum. The first pair are rounded with a broad transverse bar of brown pigment 

 in front. The succeeding are reniform, and the posterior more or less ovoid. They are 

 finely veined, and as smooth under a lens as in H. marphysse, but show a dense group of 

 horny papillse in front of the scar, that is, near the hollow of the reniform kinds. The 

 coloration of these scales is varied. Thus some of the Zetlandic examples are faintly 

 tinged with brown toward the posterior border ; in others each scale has a brownish 

 ring, or the brown pigment forms a bold border on the inner third, and sends a process, 

 in some cases enlarged near the termination, toward the centre of the scale, so as to 

 simulate a V. The spot or enlargement is at the scar. In the forms from St. Andrews 

 the pigment assumes the shape of the shell of Pandora, with a spot (over the peduncle) 

 corresponding to the hinge anteriorly. The colours are for the most part retained after 

 immersion in spirit. The persistent attachment of the scales is not a feature character- 

 istic of the Zetlandic forms, for they readily fall off. 



Feet. — The first foot has the usual spine and a few bristles resembling the dorsal. 



The dorsal division of the second foot bears a larger group of bristles than in 

 H t marphysse, with similar fine rows of spines, and the bristles are generally larger and 

 stouter. The ventral series are fairly developed, the upper and lower with simple, the 

 median with distinctly bifid tips, though the secondaiy process is slender. 



In the third foot both dorsal and ventral bristles are longer and approach more 

 nearly to the typical forms. They are also more numerous. 



In the typical foot (Plate XXX, fig. 4) the dorsal division is more developed than in 

 H. marphysse, and the bristles attain a size never seen in that species, though it has to 

 be borne in mind that the environment may have considerable influence in modifying 

 these and other parts. They are long, tapering, slightly curved, and finely spinous 

 bristles (Plate XXXIX, fig. 12, in profile, and Plate XXXIX, fig. 13, antero-posteriorly, 

 so as to show the alternate disposition of the spines, both representing the longer and 

 more tapering forms next the ventral). Some, however, are even more finely tapered 

 than the forms shown. The spines proceed almost to the tip, a mere trace of a terminal 

 smooth portion being present. Those next the body are much shorter and less tapered 

 (Plate XXXIX, fig. 14). Parasitic infusoria and slender algaa are common on these 

 bristles. The ventral division of the foot is somewhat less elongated than in 

 H. marphysx, and the bristles form a more regular fan. Superiorly the spinous region is 

 longer, and the tips more finely tapered (Plate XXXIX, fig. 15) ; the secondary process, 

 which appears to be present in all at this edge, being very closely applied to the larger 

 division, which is scarcely hooked. In a variety from Guernsey some of these bristles 

 have simple tips. The fissure between the divisions becomes more evident as the 

 spinous region diminishes in length, but it again is less distinct ventrally, some at the 

 extreme verge having a mere trace of this process. A bristle from the middle of the 

 ventral group is drawn in Plate XXXIX, fig. 16. Their colour throughout is very pale 

 yellow. Microscopic filamentous algas occur on them. 



The dorsal cirri are rather short, tapering organs, with scarcely a trace of an 

 enlargement below the filiform tip, and the short clavate papillae are sparsely distri- 

 buted. The ventral cirri are comparatively slender, and the tips reach considerably 



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