1903.] NATURAL SCIENCES OF PHILADELPHIA. 415 



Xepidonotus (Hylosynda) vexillarius sp. nov. (PI. XXIII. fl<;s. 1:5. 14, 13.) 



A rather slender species, measuring 23.5 mm. in length. 2.5 mm. in 

 maximum breadth of body on the ventral surface of X. 4 mm. to ends 

 of parapodia, and 5.5 to tips of setse. 



Prostomiimi slightly wider than long, sides smoothly convex without 

 any prominent lateral lobes, posterior margin for its middle half con- 

 tinuous with peristomium. frontal sinus very shallow. Eyes 2 pairs, 

 black, circular; the anterior larger and situated close to lateral margins 

 at widest part of head; posterior on postero-lateral curvature, looking 

 ■caudad, dorsad and laterad. ^ledian tentacle arises from dorsal sinus 

 nearly on the level of the dorsal surface of the prostomium; its 

 ceratophore about f as long as prostomium. white with a very con- 

 spicuous circular light brown spot covering most of the dorsum of the 

 basal half; style scarcely three times as long as prostomium, of grace- 

 ful form, tapering very gradually for the first f , then increasing even 

 more gradually to near the end of the next f , then suddenly rounding 

 off and bearing a delicate terminal filament, which makes up the final 

 ^; colors very pretty, rather dark brown at the base but fading grad- 

 ually to white, with a deep brown, sharply-defined ring on the basal 

 half of the subterminal enlargement, the remaining half and the ter- 

 minal filament white. Ceratophores of lateral tentacles continuous 

 with frontal processes of head, on the same level as the median cerato- 

 phore but only t ^s long and little more than h as thick ; styles twice the 

 length of the prostomium, of nearly equal diameter to the median 

 tentacles, and terminal filament constituting nearly ^ of their length ; 

 ceratophore dark brown, contrasting strongly with the colorless pro- 

 stomium, a very narrow terminal white ring, styles colored as on median 

 tentacle. Palpi reach to base of terminal filament of median tentacle, 

 their bases broad, mostly concealed from above by the tentacular cerato- 

 phores and buccal parapodia, taper rapidly in a concave outline to a 

 rather slender terminal half ending in a short filament; pale brown 

 throughout. 



Peristomial parapodia of the usual form. Tentacular cirri with styles 

 similar to median tentacle in form and color, but with longer filament; 

 the dorsal exceeds the ventral by the length of its filament and equals 

 the median tentacle. There are 36 somites, exclusive of the pygidium, 

 of which 35 are setigerous. Body smooth both dorsally and ventrally, 

 the neural depression well marked and about as wide as the muscle 

 ridges. No nephridial tubercles can be detected, but small dark spots 

 in their usual position appear to be pores. Dorsum of the first 12 

 somites marked with brown spots of diminishing size, a small brown 

 postanal spot, rest of body colorless. 



