SCOLOPLOS. 509 



largo and tapered, and project considerably beyond the spines. Little change occurs at 

 the sixteenth foot except that the bent tips of the spines towards the middle and lower 

 part of the row are slightly clavate, that is, bluntly rounded and somewhat enlarged. 

 The posterior papillae are still tapered and rather long. The seventeenth and eighteenth 

 feet are similar, but have fewer bristles, thus making a shorter row. A few short, 

 tapering, serrated forms are also present ; moreover, there are a few bifid forms with 

 the limbs well separated and with a mucro at the tip, their inner edges being spinous. 

 They radiate from a narrow base, as the long bristles do, only their tips are curved and 

 modified for special service. The dorsal cirrus is elongate-lanceolate, the tips of the 

 bristles being serrated (camerated), whilst the long shaft is smooth. The papillae are very 

 conspicuous, and at the nineteenth foot they have the margin of the division to them- 

 selves, for the stout and modified spine-like bristles are few and project little, whilst near 

 the upper edge of the ventral division a few very slender and apparently smooth bristles 

 with finely tapered tips project. Amongst these is a short (broken ?) slightly bent shaft 

 with a rounded tip. These bristles would appear to be modified by their surroundings, 

 as well as by the adaptability of the tissues which form them. The dorsal cirrus is 

 a conspicuous flattened process, and the dorsal bristles are longer, the whole foot 

 initiating the change, though the projection of the spinigerous lobe is scarcely marked, 

 At the twenty-third foot the alteration is complete, the large branchia being internal, 

 then follows the somewhat subulate dorsal cirrus, with a slight enlargement on its external 

 edge, and the long dorsal bristles with slight serrations on their finely tapered tips, 

 accompanied by a few bifid forms. The ventral lobe is clavate, bifid at the tip, the 

 shorter process being rounded and containing the spine, whilst the other (ventral) forms 

 a considerable subulate appendage. The bristles are few, slender and tapering, scarcely 

 a trace of serrations being visible. The ventral cirrus is a subulate process resembling 

 the appendage above it. 



Whilst approaching Aricia Cuvieri this form differs in the number of the anterior 

 segments, the absence of the cirrus between the dorsal and ventral divisions, and in the 

 great length of the papillae in the ventral rows. The number of the anterior segments 

 likewise differentiates it from A. Kujpfferi and A. norvegica, as also do the form and 

 arrangement of the papillae behind the ventral division and on the ventral surface 

 of certain segments. 



Genus LXXVIII. — Scoloplos (Blainville), CErsted. 



Head pointed, peristomial segment a blunt cone. Proboscis a foliate rosette. Body 

 widened anteriorly, flattened, diminishing posteriorly, and ending in a vent with four 

 papillae and two cirri. Regions of the body two, anterior and posterior ; the former with 

 the feet lateral, the latter with the feet dorsal. Branchiae dorsal, ligulate, decreasing in 

 size posteriorly and disappearing. Inferior division of the foot in the anterior region 

 with a small papilla. Long, tapering serrated dorsal bristles, and stout, serrated spine- 

 like bristles ventrally. In the posterior region the bristles are all slender and serrated. 

 The structure of this type generally approaches that of Aricia, though the rows of papillae 

 on the feet are absent. 



