SABELLARIA SPINULOSA. 15 



rudimentary. All, however, have the asymmetrical base as in the other types of the 

 second and third rows. 



The second row consists of modified bristles with a slender shaft tapering to a 

 point at its base, and of a proportionally massive tip shaped like a broad bill-hook 

 (Plate CXXIII, fig. 2 a). The shaft tapers from its upper end to its pointed base and is 

 comparatively slender. It curves posteriorly into the convex margin of the tip, whilst 

 anteriorly it abruptly expands into a thin edge, which is concave in its progress to the 

 pointed tip. Moreover, a second outline occurs within the foregoing, so as to simulate 

 a double edge, as if a trace of a double wing were present. The thin edge beyond the 

 inner line is boldly striated transversely throughout, and curved transverse striae cross 

 the greater part of the tip, but not the base. A shorter series of these bristles also occurs 

 (Plate CXXIII, fig. 2 b). 



A considerable number of the bristles in this (second) row present a further stage in 

 the modification of the tip, which forms a long, curved, tapering structure with the 

 double outline on the anterior face and the transverse striae throughout the greater part 

 of its extent. The two ridges on the anterior face are evidently modifications of wings, 

 and the point is acute. The shaft is long and tapers from the upper part to a point at 

 the base, whilst the posterior curve comes off distally before the anterior and is less abrupt. 

 The anterior outline swells into the " heel " of the tip and is specially striated. In the 

 St. Andrews forms these chiefly occur at the ventral edge. In those from Luccomb 

 Chine, Isle of Wight, they occur all along the second or middle series. 



In the variety ensifera from Lochmadcly and Guernsey several of the paleae of the 

 second row form long needle-like processes projecting far beyond the rest, and giving a 

 character to the crown. Such occur in the young as well as in the adults from both 

 places. Fauvel found a similar variety at St. Thomas. 



The third or inner row has another modification, the tip leaving the thin shaft at an 

 angle greater than a right angle, and resembling a long foot with a pointed toe, the 

 resemblance being the closer since the heel and foot have a different axis from the shaft. 

 The shaft is proportionally the most slender, and the bending of the tip backward 

 causes the heel (anterior projection) to stand out prominently. Bold transverse striae 

 occur on the face between the ridges, so as to make a rasp-like surface to which 

 mud adheres. Finer striae are found on the heel and on the tip apart from the ridges. 

 These bristles form a spiny guard to the oral aperture, and are often covered with 

 muddy debris. 



The crown is supported on a firm fleshy pillar, slightly bifid dorsally, and more 

 distinctly so ventrally, its surface dorsally and laterally being variegated with purplish or 

 madder brown pigment — often arranged in bands dorsally and at the sides of the tentacles 

 ventrally. A circle of acute tapering and highly sensitive (Arnold Watson) papillae 

 pointing forward surrounds the base of the crown, aud a brown pigment-band passes 

 from the sides ventrally to the fissure. 



Amidst the paleae of two specimens from Southport are numerous examples of a 

 parasite akin to Udonella. 



In the Scottish forms variations in the length of the tips of the second row of paleae 

 are not uncommon, two or more of these on each side occasionally forming conspicuous 



