202 



BUSH 



Genus Aspeira nov. 



Type, Aspeira modesta sp. nov. 



Branchial lobes with small basal attachment, not spiral, without 

 ventral prolongation, and united dorsally, bearing a single series of 

 moderately long, simple plumose branchiae of about equal length, their 

 rachises rounded on the back and, along the two inner edges, having 

 a conspicuous ruffled membrane, most developed posteriorly, outside 

 of which the long, rather coarse, well-separated (especially posteriorly) 

 pinnae arise ; these extend nearly to the end of the rachis, leaving but 

 a very small tapered tip. Eyes none. 



Collar bilobed, as in Potamilla^ arising from the dorsal furrow and 

 continuing in an unbroken curve to the ventral fissure, where it ab- 

 ruptly expands into long, narrow, triangular processes, twisted strongly 

 backward. Inside the collar are two well-marked dorsal cephalic 

 swellings. 



A conspicuous ruffled membrane extends inward from the ventral 

 fissure of the collar, inside each branchial lobe, folds on itself, and 

 terminates at the ventral end. On each side of the mouth is a very 

 large, irregular, leaf -like membranous lobe supporting a long, slender, 

 dorsal tentacle, which is attached near its base to the inside of the 

 branchial lobe. 



Fascicles of setae laterally elongated as in Pseudopotamilla and 

 Eudistylia, 



Setae of the collar fascicle and superior ones of the other thoracic 

 fascicles, with regularly tapered, lanceolate blades ; inferior setae, 

 back of the collar, vary from oblanceolate (the longer) to subspatulate 

 (the shorter) forms ; abdominal setae bent at the base of the long, 

 abruptly tapered blade. Thoracic tori with avicular hooks and pen- 

 noned setae ; abdominal tori with avicular hooks only. 



This genus forms a connecting link between the genera Parasahella 

 and Potamilla, 



ASPEIRA MODESTA sp. nov. 

 p1. XXV, fig. 3 ; p1. xxxvi, figs. 27-31, 33-35. 

 Tyfe locality. — Kadiak. 



Color in formalin yellowish, with the branchiae broadly and irreg- 

 ularly banded with light chestnut. 



Number of segments about 90, with 6 on one side of the thorax and 

 7 on the other ; the fascicles of setae in slightly oblique series. 



Branchiae about 11 mm. in length, arranged in a single series of 13 

 equal pairs, besides 2 small undeveloped ventral ones. 



