STAUEOCEPHALUS CILIATUS. 361 



row of hard horny points which guard each side of the pharyngeal slit. The elaborate 

 series of muscles which move these denticles, and their conformation, denote important 

 functions. In this species (Plate LXI, fig. 9) the lower row has a dense series of strongly 

 curved dark brown denticles with a median and two or three lateral teeth. They have 

 their maximum development toward the posterior third of the row, whereas in front they 

 form a comparatively even series of smaller and less dusky teeth. Posteriorly the row 

 terminates in a thickened dark brown band with irregular denticles. The upper row 

 commences anteriorly in what seems to be a series of pale brown horny filaments which 

 merge into the somewhat long teeth of the row, the curves of which, like those of the 

 lower row, are directed backward. Posteriorly the teeth diminish in length but increase 

 in robustness, and have toward the inferior end a brown hue as deep as that of the lower row. 

 The row terminates in a band of small denticles. Besides these rows a less developed 

 accessory row occurs to the outer side of them, and on one side a similar row on the 

 inner side. Ehlers shows a similar accessory row in Staurocepl talus rubrovittatvs. 



The mandibles (Plate LXI, fig. 9 a) are shaped somewhat like a boomerang, and have 

 on the produced anterior edge a series of eight deeply-cut teeth, besides three separate 

 denticles at the outer edge. 



The nerve-cords in the preparations are flattened in transverse section, but such may 

 be due to the methods of preparation. 



The feet of this form are distinguished from those of the Hebridean species by the 

 presence of a well-developed dorsal cirrus, which appears on the second foot. At the 

 twentieth foot (Plate LXXIII, fig. 6) the parts have attained an average outline and 

 structure. Dorsally is the stout cirrus with a slender central spine proceeding as far as 

 the articulation of the terminal process, which is, proportionally, of considerable length. 

 The setigerous region is large, bevelled superiorly, the outline in lateral view trending to 

 the prominent inferior border whence the compound bristles arise. This prominent 

 region attains even greater development posteriorly. Inferiorly, at some distance from 

 the edge, the obovate ventral lobe projects outward beyond the setigerous region, less, 

 however, than does the dorsal cirrus. 



Superiorly two bristles occur, viz. (Plate LXXXI, fig. 11), along, slender, translucent 

 bristle with a somewhat abrupt curve below the serrations and a finely tapered tip, on 

 the slender terminal region of which the serrations become indistinct. They are directed 

 distally, and are most distinct inferiorly. Accompanying this is a stronger translucent 

 bristle (or two) with a straight shaft and a dilated, bifid extremity (Plate LXXXI, fig. 11 a), 

 one of the legs of the fork being shorter, broader, and more acute at the tip, the other less 

 expanded and longer. Traces of two spines occur on the edge beneath. The inferior 

 group consists of compound bristles (Plate LXXXI, fig. lib and b ! ) with translucent shafts, 

 curved, with the convexity upward, and dilated and bevelled distal ends which are also 

 serrated. The terminal piece, as usual, varies in length, diminishing from the upper to 

 the lower bristles, one of the shorter being represented in the figure. The tip is bifid, a 

 secondary process passing forward nearly parallel with the axis of the terminal piece to 

 the distal hook, and thus differing from such as have the secondary process projecting at 

 a larger angle. 



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