88 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



prostomium, with ommatophores, is not quite half again as long as wide. 

 The smaller sessile eyes are located near the lateral margins, the anterior 

 eyes on short, thick stalks. The median antenna is inserted near the 

 middle of the prostomium. There is a shallow median sulcus (pi. 26, 

 fig. 309). 



Setae include superior penicillate (pi. 26, fig. 310), median aristate 

 (pi. 26, fig. 311) characterized by their spinose tips, and inferior, 

 scythe-like setae (pi. 26, fig. 312). There are about 7 penicillate setae 

 in the twentieth parapodium, about 14 larger aristate setae and 5 simi- 

 lar smaller ones. The inferior scythe-like setae are strongly spinose. 



Another specimen (244-34) is macerated, but agrees with P. pacifica 

 in that the ommatophores are short, stout, the median antenna is in- 

 serted in the same way, the setae are markedly spinose. Sessile eyes can- 

 not be made out. There is, however, a diffuse dark spot in the area 

 where they would be. 



Numerous specimens, in the author's collection, from southern Cali- 

 fornia, indicate that this is the most common species of Polyodontidae 

 in the subintertidal zone, where the substratum is green or black mud. 

 It constructs thick-walled, finely matted, mud masses or balls, from 1 

 to 6 or 8 inches long. Each mass is usually inhabited by a single indi- 

 vidual, but two, lying end to end, have occasionally been seen. The 

 outer color is that of the mud inhabited, the smooth lining is usually 

 rust colored. The tubes, though occurring in soft, oozing mud, are too 

 toughly matted to be torn without disrupting the contents. 



Distribution. — Southern California (common) ; Point Tosca, Lower 

 California, Mexico; ?Bahia Honda, Panama. Subintertidal to 50 fms. 



Panthalis marginata, new species 

 Plate 26, Figs. 313-318 



Collection. — 770-38 (Holotype). One specimen, fragmentary. 



The palpi and tentacular cirri of the first (apodous) segment are 

 transversely barred with black on the dorsal and lateral sides ; the elytra 

 are brown, with white margin. The first elytra are elongated in an- 

 terior-posterior direction and have an elongated, subrectangular flap at 

 their ectoposterior portion (pi. 26, fig. 313). This flap lies normally 

 over the long ventral cirrus of the first, and all of the second, para- 

 podium. 



