306 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



5. Major spines of fifth segment falcate with pectinate top 



P. brachycephala Hartman 



5. Major spines of fifth segment otherwise 6 



6. Branchiae present from tenth setiger to about the twenty-fifth, a 

 posterior region abranchiate .... P. giardi, p. 309 



6. Branchiae present from seventh or eighth setiger .... 7 



7. Major spines of fifth setiger of 2 kinds, falcate and tricuspid 

 P. tricuspa Hartman 



7. Major spines of fifth of a single kind, not tridentate ... 8 



8. Major spines of fifth segment with a lateral, sheathlike tooth (pi. 

 48, fig. 40) ; branchiae present from seventh segment 

 P. ciliata, p. 308 



8. Major spines of fifth segment falcate, with boss in concavity (pi. 

 48, fig. 41 ) ; branchiae present from eighth segment 

 P. socialis, p. 310 



Polydora armata Langerhans 

 Plate 48, Figs. 38, 39 



Langerhans, 1880, pp. 93-94, pi. 4, fig. 5; Fauvel, 1927, pp. 55-56, 

 fig. 19; Okuda, 1937, pp. 230-231, fig. 10. 



Along much of the intertidal zone of southern California, where low- 

 lying reefs, flat rocks, and shallow crevices are found, harder surfaces are 

 frequently covered over by an encrusting pale red alga. Some of these 

 masses appear coarsely prickly; at the tip of each small elevation a small 

 aperture may be distinguished. These mark the openings of burrows of 

 P. armata. The burrows ramify irregularly through the calcareous matrix. 



Specimens from La Jolla are small, inconspicuous, number of seg- 

 ments about 32. The prostomium is weakly bifid at its anterior margin; 

 it lacks eyespots (observed in life). Branchiae are first present from the 

 seventh segment, number only 5 or 6 pairs, and are continued on segments 

 7 to 12 or 13 ; they are large, with long cilia continued along their length. 

 The first segment has both dorsal and ventral setal fascicles. 



The fifth segment has a dorsal fascicle of stout spines accompanied by 

 bipinnate setae and a ventral fascicle of about 5 slender capillary setae. 

 The modified spines have a falcate tip with heavy flange at the geniculate 

 portion (pi. 48, fig. 39). Hooded hooks are distally bifid (pi. 48, fig. 38), 

 present from the seventh segment to the end. Parapodial glands occur in 

 segments 7 to 11. Fascicles of heavy spines are present in notopodia of the 



