98 STYLARIOIDBS ARENOSA. 



bristles posteriorly are fairly conspicuous; indeed, in some this fringe to the caudal 

 segments is more evident than in the majority of the specimens of S. plumosa, since the 

 dorsal bristles form a fan. 



Reproduction. — In examples from St. Magnus Bay, and also from Dingle Bay, in 

 July, large ova occurred anteriorly, and apparently were ovarian, since many had a stalk 

 or process attached. 



Fauvel (1907) considers the Trophonia hirsuta of Hansen as identical with this form, 

 while Miss Newbigin (1900) thinks them distinct. 



3. Stylarioides arenosa, Webster, 1879. Plate XC VI, fig. 3 ; Plate CIV, figs. 0—6 d, 



Specific Characters. — Palpi grooved and crenate ; branchige numerous (Webster says 

 " red at base, green externally "). Body about 2 in. in length, firm and more or less 

 rounded from a dense coating of adherent sand-grains, and in the preparations grooved 

 anteriorly, either dorsally or ventrally, from contraction, slightly tapered anteriorly, and 

 gently diminished to a blunt tail, with the anus in the middle. Segments distinct, 

 60 — 70. First three sets of articulated bristles longer than the rest, and with the next 

 two directed forward, shorter than in S. plumosa, more slender, pale yellow, and 

 resplendent. Ventral of the third series shows a hooked tip with an adnate secondary 

 process, and in its progress backward the edge of the latter is differentiated into a separate 

 process, either by use or otherwise, and the whole flattened hook becomes shorter and 

 more densely articulated. 



Synonyms. 



1879. Trophonia arenosa, Webster. Trans. Albany Instifc., vol. ix, p. 45 (sep. copy), pi. vii, figs. 



92—97. 

 1908. Stylarioides arenosa, Mcintosh. Ann. Nat. Hist., ser. 8, vol. ii, p. 531. 



Habitat— At low water-mark, St. Peter Port, Guernsey, July, 1868. 



It was first found between tide-marks, Northampton County, eastern shore of Virginia 

 (H. E. Webster). 



Branchias six to eight or nine in number ; tips pale in the preparation, then with a 

 reddish-brown bar followed by a pale base. Webster states " branchige very numerous, 

 filiform, red at base, green externally ; the inferior shorter than the superior." 



According to Webster, the " tentacles are not quite so long as the branchige, canali- 

 culated margin scolloped ; colour reddish-brown with a green centre." 



Body (Plate XCVI, fig. 3) rounded, about two inches in length, enlarged anteriorly, 

 but less bulbous than 8, plumosa, diminished a little in front and tapering posteriorly to a 

 blunt tail. Segments sixty-two to seventy. It is distinguished by its somewhat firm 

 consistence and a tendency to have a groove either ventrally or dorsally anteriorly, as 

 well as by its dense coating of sand-grains. The segments are distinctly marked from 

 the first to the last, and, in so far as the first three and to a less extent the following two 

 sets of bristles are directed forward, the resemblance to S. plumosa is greater than to 



