186 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 



setigerous tubercle bearing a few long capillary setae and the 

 notopodium retaining a small flattened postsetal lobe. 



Branchise occur on somites III, IV and V, but on the left side 

 only of the latter. Whether they have been lost from other seg- 

 ments is uncertain. They all arise immediately above and very 

 slightly in front of the neuropodium to which they belong and 

 when fully developed are from 2 to 2^ times the width of the 

 body and stand more or less erect. Thej'' consist of tapering, 

 slightly articulated stems, each bearing a double row of about 

 forty flattened pinnae on the caudal face. The pinnse begin slightly 

 above the base and increase in size distally. The first and second 

 gills on the right side are evidently in process of regeneration and 

 consist of a delicate filament with rudimentary pinnse. Apparently 

 all are alike when fully developed. 



Setse bundles form broad dense fan-shaped fascicles, the noto- 

 podial being much larger, of long capillaries curving strongly 

 backward. Further caudad, as the parapodia become smaller, the 

 fascicles become more diffuse, the setae straight and their number 

 reduced. Anterior notopodial setae moderately stout, strongly 

 curved, tapered to acute tips, nearly colorless, formed of an outer, 

 hard, longitudinally striated shell and an inner more opake, finely 

 granular core. On the branchial segments, they are longer and 

 curved dorsad, 021 post-branchial segments shorter and curved 

 rather strongly caudad. At about XIV, ihey become straighter 

 and more delicate and reduced in number, and continue to be 

 reduced until by L they become very inconspicuous. 



Neuropodials are similar to notopodials but shorter and become 

 reduced more quickly. At about XX, crochets appear and by 

 XXV have replaced one-half of the setse, there being 13-15 small 

 hooded crochets and an equal number of delicate colorless setse, a 

 condition which continues to LII at least. 



Station 4549, off Point Pinos Lighthouse, 56-57 fathoms, coarse 

 sand, shells and rock. 



CHiETOPTERIDAE 

 Spiochaetopterus sp.? 



Tubes of two species having exactly the form and structure of 

 those of Spiochcetopterus, but entirely lacking remains of their 

 fabricators were taken at a few stations. 



One is a large form measuring 4-6 mm. in diameter and collected 

 at Stations 4410, off Santa Catalina Island, 178-195 fathoms, gray 

 sand; 4418, off Santa Barbara Island, 238-310 fathoms, black mud 

 and gray sand. 



The other form of tube is only 1-1.5 mm. in diameter, long and 

 slender. Stations 4431, off Santa Rosa Island, 38-45 fathoms. 



