1923J NATURAL SCIENCES OF PHILADKI.PHrA 243 



and pointed in I-anopcan examples of the species are even more 

 so in this. 



Stations 4433, off Santa Rosa Island, 243-265 fathoms, green 

 mud; 4435, off San Miguel Island, 274-287 fathoms, green mud. 



Another small specimen taken from a tube attached to a colony 

 of Pseudopotamilla splendida may be an aberrant example of this 

 species. It has only seven setigerous thoracic segments. 



Station 4341, off South Coronado Island, 2()6 323 fathoms, 

 gray sand. 



Potamilla californica Treadwell . 



A large specimen was so difficult to remove from a tightly coiled 

 tube that complete study was impossible but it conforms to the in- 

 complete description of this species. 



Length about 100 mm., of which the thorax comprises 12 mm., 

 and the gills 16 mm., diameter 4.5 mm. Branchiophores simple, 

 low, not produced ventrally or obviously involuted. Radioles 

 twenty-six pairs, free, rather stout, broadly winged on median 

 dorsal margins, the barbs short, very numerous and crowded, 

 leaving a distal broad naked tip which on the dorsal radioles has a 

 length equaling one-half the width of the thorax. They bear no 

 definite eyes but numerous minute specks of brown pigment. 

 Nine or ten zones of small brown pigment spots are confined 

 chiefly to the bases of the barbs. 



Station 4496, off Santa Cruz Lighthouse, 10 fathoms, fine gray 

 sand. 



Potamilla sp. 



Other empty tubes of a Potamilla were taken at stations 4463 

 and 4496. 



Notaulax mucronata sp. nov. Plate XVIII, figs. 4.3, 44. 



Gills 15 pairs including three or four central ones which are some- 

 what inturned. Branchiophores or bases very small, weakly at- 

 tached, somewhat prolonged ventrally but not spirally coiled. 

 Radioles differ greatly in length in different specimens (from 3- to 

 nearly | total length) chiefly due to their easy loss and regenera- 

 tion. They are completely free to the bases, there })eing no trace 

 of an interconnecting membrane, thick, rounded and entirely 

 without appendages, wings or margins. Barbs very delicate, 

 elongated and widely separated, becoming shorter distally, where 

 a considerable tip of the radiole is left naked. 



Collar probably somewhat abnormally retracted, closely ap- 

 pressed to branchial bases and with flaring margins divided by 



