488 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



dorsal (pi. 63, fig. 2). The pygidium may lack tentacular processes 

 (some species of Pilargis) or there may be a pair of such structures (some 

 species of Pilargis and Ancistrosyllis) or there may be an anal plaque with 

 prolonged processes (Loandalia). The terminal end is not known for 

 species of Talehsapia and Cabira. 



In so far as known, representatives of the family Pilargiidae do not 

 construct tubes. Known habitats include sand and mud flats, or rocky 

 crevices in intertidal zones but some species have been recorded from 

 moderate to abyssal depths. Although only a few species are known, 

 mainly by their original accounts, their geographic distribution is world 

 wide, in both northern and southern hemispheres and they occur in arctic 

 to tropical zones. 



With few exceptions, the family characteristics discussed above are 

 highly reticulate. The only constant characters pertain to the small size 

 of the prostomium, the apodous condition of the peristomium, the reduced 

 notopodium with its dorsally emerging acicula and setae, and the entire, 

 simple setae of both notopodia and neuropodia. It might be suggested 

 that some deviation is the result of loss or reduction of parts. At any 

 rate, the species of Ancistrosyllis appear to be the most generalized since 

 they retain, in some instances, well-developed prostomial palpi ; 3 pros- 

 tomial antennae, prostomial eyes, more or less well-developed peristomial 

 cirri, biramous parapodia with setal structures in both rami and both 

 dorsal and ventral cirri and the anal end is generalized. Extreme reduc- 

 tion appears to have occurred in species of the genera Loandalia and 

 Talehsapia where prostomial antennae and peristomial cirri are totally 

 lacking. Here also the anal end is greatly modified and the nature of 

 parapodia with their arrangement and details of setae depart very widely 

 from similar parts in other genera. 



Characters common to Ancistrosyllis and Pilargis 



Body long, flattened to ribbonlike or depressed cylindrical 



Epithelial papillae more or less strongly developed to absent 



Prostomium with well-developed biarticulated palpi 



Prostomium with a pair of simple antennae 



Peristomium with 2 pairs of cirri 



Proboscis lacks jaws 



First setigerous segment with dorsal cirri and sub- to biramous parapodia 



Neurosetae with cutting edge provided with a single row of teeth 



