1923] NATURAL SCIENCES OF PHILADELPHIA 183 



As these become large both rami are reduced. Following the 

 disappearance of the gills at XLIII to XLIX the neuropodia are 

 reduced to small setigerous tubercles with only a thin inconspicuous 

 post-setal lobe, being dwarfed by the large interpodal pockets. 

 Notopodia are similar in form but larger and are united with the 

 body al)Ove by thin transverse folds and to the neuropodia by 

 similar folds. 



Gills begin on III and continue on different specimens to from 

 XLIII to LI, occupying the same position as in Scolelepis. At 

 first very small, by XV they are fully developed and as long as 

 one-half the body width, semi-erect, slender, tapered, lanceolate 

 and marked on the caudal face with numberous plications corres- 

 ponding to the arrangement of the blood vessels. At about XXXV, 

 they begin to diminish in size, the last few usually being mere 

 tubercles, and disappear at from XLIII to LI according to the 

 size of the specimen. 



Both rami of anterior somites bear dense fan-shaped fascicles of 

 internally granular, yellowish, strongly curved setic in two series, 

 the onl}" difference being that the notopodials are somewhat 

 longer. Passing caudad they gradually l)ecome less curved and 

 reduced in size and number, finally forming small fan-shaped 

 fascicles of straight seta^ in two ranks, those of one being much more 

 delicate than those of the other. A few small hooded crochets 

 appear in the middle of the neuropodial fascicles immediately 

 succeeding the branchial region, but they replace the setae much 

 more gradually than in S. sacculota and are always fewer, much 

 smaller and much more inconspicuous. For example, at LX, 

 there are 22 neuropodial setae and two crochets; at LXXX, 12 

 setae and 10 crochets. 



No specimen is complete and a region of uncertain length between 

 the middle and the caudal segments is unknown. The most com- 

 plete specimen, designated as the type, consists of the head and 

 111 setigerous segments. This is 62 mm. long, with a maximum 

 breadth of 4.2 mm. Other sjx'ciincns vary from l.o to r).2 mm. in 

 width. 



Stations 4343, off S. Coronado Island, 55-155 fathoms fine 

 gray sand; 4428, off Santa Cruz Island, 764-891 fathoms, green 

 mud; 4430, off Santa Cruz Island, 197 281 fathoms, l)lack saml and 

 pebbles; 4457, off Point Pinos Lighthouse, 40-46 fathoms, dark 

 green mud; 4464, same locality, 36-51 fathoms, soft, dark gray 

 mud, (12 specimens); 4524, same locality, 213-228 fathoms, soft 

 graj^ mud; 4549, same locality, 56-57 fathoms, coarse sand, (type 

 and 2 others); 4550, same locality, 50-57 fathoms, green mud; 

 4552, same locality, 66 73 fathoms, green mud; 4557, same localitj', 

 53-54 fathoms, rocks. 



