128 POLYMNIA NESIDBNS1S. 



it is not usually folded backward as in that species; moreover, no eyes are present in 

 many of the preparations. The upper lip in front of this forms a large frilled process, 

 and the lower lip is also prominent. A median tongue-like process lies above and 

 internal to the latter. In extreme protrusion of the mouth-parts some have the lower 

 lip folded backward ventrally with a smaller and a larger fold above it, whilst in others 

 the lower lip projects downward and outward as a cyathiform process marked by a fold 

 at each side. 



The body is comparatively small in comparison with P. nebulosa, is convex and 

 smooth dorsally, deeply grooved ventrally from the ventral shields almost to the tip 

 of the tail, which in perfect examples has two longer median and two lateral cirri on 

 the ventral surface, the rest of the vent being crenated or with short papillae. Two 

 segments following that bearing the lower lip have a lamella at their outer edges 

 ventrally, and are opposite the first and second branchiae. The anterior, indeed, 

 often stands out as a frill on the front edge of the shield. In all, about sixteen 

 shields are present ventrally, and they bear traces of the two-ringed condition of the 

 segments generally. They are narrow and transversely elongated in front, broad and 

 transversely shortened posteriorly. The ventral groove abuts on two rounded lateral 

 ridges (probably marking the ventral longitudinal muscles), and bearing the elevations 

 or lamellae for the hooks. The segments are two-ringed. It is a smaller species than 

 Polymnia nebulosa, and of a firmer consistence. Colour yellowish, with brownish grains, 

 ventral surface dull yellow (chamois, Marenzeller). 



The branchiae are three in number, the anterior being the largest, the second and 

 third regularly diminishing. In proportion to the size of the body they are somewhat 

 larger than in P. nebulosa, and they have a stiffer outline. They are dichotomously 

 branched, and have very short terminal divisions — a distinctive feature when contrasted 

 with P. nebulosa. A variety (?) from the West Voe of Scalloway, in 6 — 8 fathoms, has 

 longer tips to the branchiae, but the hooks appear to be identical. 



The setigerous processes are seventeen in number, the first occurring close to the 

 base of the last branchia. The bristles are long, translucent, slightly yellowish and 

 finely tapered (Plate CXXVa, figs. 5 and 5 a), and, as usual, in two series, a shorter 

 and a longer. In the latter the wings are narrow and indistinct ; in the former they are 

 broader and easily recognised, but they do not proceed to the finely tapered extremity 

 of the bristle. A curvature of the tip occurs at the winged region. Little difference 

 exists between the first bristles and the last except in the fewer number as contrasted 

 with the middle and anterior groups. 



The rows of hooks commence on the second bristled segment, and they are 

 comparatively short to the seventh bristle-bundle, the last ten of the region being 

 longer. Moreover, whilst they form a single row in front they are arranged in a double 

 row from the eleventh to the twentieth segments, the main fang in each pointing to 

 a median line between the rows. Behind the bristles the hooks are borne on an 

 uncinigerous process or lamella, and form shorter rows than in front. The lamellae have 

 a concave distal margin anteriorly, but posteriorly the tip is bifid, and the processes 

 diminish toward the tip of the tail. 



The hooks (Plate CXXVa, fig. 5 6) somewhat resemble those of Polymnia nebulosa, 



