1923] NATURAL SCIENCES OF PHILADELPHIA 185 



Both rami bear dense, vertical, spreading fan-shaped fascicles of 

 long curved capillary setae, the notopodial fascicles being larger 

 and the seta; longer. As the rami become smaller, the fascicles are 

 correspondingly reduced, but the notopodial set® undergo little 

 reduction in length though becoming straightcr and more slender. 

 Hooded crochets appear in the ventral part of the neuropodium 

 at about LV and increase in number as the gills cease and through- 

 out the post-branchial region and soon replace all l)ut a few very 

 small setae of which some remain in the ventral part of the bundle 

 to the end of the piece. The crochets are stouter than the setae 

 and darker colored. 



There is a broad, nearly black longitudinal neural stripe on ])oth 

 specimens. 



Stations 4429, off Santa Cruz Island, 506-580 fathoms, green 

 mud; 4452, off Point Pinos Lighthouse, 49-50 fathoms, green mud; 

 4525. same locality, 222 fathoms, soft, gray mud, (type). 



Prionospio alata sp. nov. 



/Type only known, an example consisting of the head and 52 

 anterior segments and measuring 29 mm. long and 1.6 mm. wide. 

 Form slender and linear, very slightly depressed and widened in 

 front. 



Prostomium a truncated ridge about five times as long as wide; 

 anterior end blunt, slightly rounded and without lateral projections; 

 caudal end more compressed and terminating in a point but appar- 

 ently lacking a tentacle. 



Peristomium biannulate, prolonged forward nearly to the tip 

 of the prostomium, united laterally with II and elevated as a pair 

 of conspicuous, thin, translucent wings with rounded margins 

 which conceal the greater part of the head, includhig the scars of 

 attachment of the detached peristomial cirri. 



Segments well defined by deep furrows which become shallower 

 toward caudal end, the anterior ones very short, but gradually 

 increasing in length until about two-thirds width, the region from 

 X to XX slightly swollen. Anterior segments are faintly biannular 

 with large podal and very short interpodal rings, but the furrow 

 soon disappears. 



First parapodium on II, rudimentary and bearing very few 

 setae. Next four conspicuous and placed at a high level, biramous, 

 the two rami closely united, with small presetal and large foliaceous 

 postsetal lol)es, that of the neuropodium sul) -triangular with the 

 point directed caudad, the notopodial about twice as large, i^xlatte- 

 shaped, with the broad free ends covering the back. Beginning 

 with VII the parapodia shift more ventrad and the foliaceous 

 post-setal lol^es becomes smaller, the dorsal extension of the noto- 

 podial and the point of the neuropodial gradually disappearing. 

 By XXV l)oth are much reduced, the neuropodium ])eing a mere 



