Gathj Marine Laboratory, St. Andrews. 531 



a shorter yet conspicuous tuft — proportionally thicker with 

 well-marked articulations and a tapered and slightly hooked 

 tip. 



The third species is Stylarioides arenosa of Webster, which 

 was procured at low-water mark at St. Peter Port, Guernsey, 

 in 1868 — that is, long before it was seen by H. E. Webster 

 between tide-marks, Northampton County, eastern shore of 

 Virginia. Mr. Webster, however, first published a description 

 of the species. The body is about two inches in length, 

 firm and more or less rounded from a dense coating of ad- 

 herent sand-grains, and in the preparations grooved anteriorly, 

 either dorsally and ventrally, from contraction. It is slightly 

 tapered anteriorly and gently diminished to a blunt tail with 

 the anus in the middle. Segments 60-70, distinct. The 

 first three sets of articulated bristles are longer than the rest, 

 and with the next two directed forward, shorter than in 

 S. plumosa, pale yellow and resplendent. The 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 other- 

 wise, and the whole flattened hook becomes shorter and more 

 closely articulated. 



The entire surface is closely beset with sand-grains, so that 

 to the touch it resembles a hard sandy tube. The papillae 

 appear to be more or less cylindrical with a clavate tip, but 

 they exhibit no evident arrangement in rows as in Mr. 

 Webster's American examples. The branchiae also appear 

 to differ, for Webster states that they " are very numerous, 

 filiform, red at the base, green externally, the inferior shorter 

 than the superior." 



As mentioned by the American author, the bristles of the 

 first five segments point forward, but the first three are most 

 conspicuous. The first is the longest, and its bristles are 

 densely coated with parasitic growths, such as thecate 

 Infusoria, algte, mud, and fragments of bristles. The ventral 

 are a little shorter than the dorsal. Though pale by reflected 

 light they are brownish by transmitted light, taper to a very 

 delicate hair-like tip, and have a series of articulations, which 

 are closer at the base of the bristle, longer in the diminishing 

 tip. The ventral of the second set are considerably shorter, 

 have a double curve, and taper to a less delicate though 

 simple tip which is slightly hooked. The ventral of the 

 third series (Webster says fourth) consist of three bristles, 

 curved at the tip and bifid, the tip indeed resembling that of 

 Sigalion and Stkenelais. The terminal segment is about 



