2IO BUSH 



Branchia? numerous, usually simple, rarely divided, generally ar- 

 ranged in a single series, sometimes irregularly biserial, plumose, with 

 a stout, gradually tapered, three-sided stem or rachis, rounded on the 

 back, without appendages, flattened and slightly grooved along the 

 inner surface, with thin membranous edges along the two angles, 

 especially posteriorly, outside of which the long slender pinnae arise. 

 These decrease in length, more or less abruptly, near the end, leaving 

 a short tapered tip. Groups of from 2 to 6 long delicate cilia, arranged 

 in alternating longitudinal rows, are found on the surface of the pinnae, 

 under a high power. 



Eyes usually present, irregularly arranged on one or both sides of 

 the back of some of the rachises. 



Collar four-lobed, meeting on the back, but little developed dorsally, 

 arching more or less abruptly from dorso-lateral notches and continu- 

 ing obliquely in a more or less undulating curve to small ventral ends. 

 A thin, wide, ruffled membrane extends inward from the ventral 

 fissure along the base of the branchial lobes to the summit of each 

 spire. Next the mouth are two large, irregular, leaf-like tentacles. 



Body more or less compressed dorso-ventrally, gradually tapered to 

 the pointed posterior end. Dorsal furrow very conspicuous anteriorly. 

 Fascicles of setae, forming more or less oblique series on the thorax, 

 of two forms : superior ones crescent-shaped, inferior ones laterally 

 elongated, protected by a conspicuous auriform membrane. On the 

 abdomen they are laterally elliptical. 



Superior setae comparatively few, with narrow lanceolate ends. 

 Inferior setae more numerous, of two forms, those of the first fascicle 

 at the base of the collar with broader ends, those of the other fascicles, 

 in 6 to 8 parallel rows, with spatulate ends. Setae on the abdomen 

 somewhat similar to the inferior ones of the collar fascicle, but longer 

 and bent at the base of the blade. Two forms in the thoracic tori 

 avicular hooks (uncini) and pennoned setae ; avicular hooks only in 

 the abdominal tori. 



This genus is readily distinguished from Distylia by the spatulate 

 inferior thoracic setae. 



EUDISTYLIA GIGANTEA sp. nov. 

 pi. xxi, figs, i, 2; pi. xxn, figs. 4, a, c, d\ pi. xxm, fig. i ; pi. xxv, fig. 4; pi. 



xxxii, figs. 1-8, 10-14, 16, 17, 21, 23-26; pi. xxxiv, fig. 23. 

 Type locality. Orca, Prince William Sound. 



Color in formalin, yellow, tinged with brown, the branchiae with 

 three conspicuous bands of dark maroon or wine color. Small speci- 



