POLYCHAETE WORMS, PART 1 277 



lateral in position ; neuropodia cushionlike, with more or less developed 

 postsetal lobes and several vertical rows of setae or crotchets; noto- 

 podia with conical or cirrifonn postsetal lobes (sometimes referred to 

 as dorsal cirri), with fan-shaped bundles of setae; (2) much longer 

 posterior abdominal region, semicylindrical, tapering posteriorly, with 

 parapodia shifted dorsally; neuropodia bilobed, with few long setae; 

 notopodia with ligulate vascular postsetal lobes, with bundles of long 

 setae. Branchiae dorsal, medial to notopodia, simple (rarely 

 branched), erect, lanceolate or straplike, strongly ciliated on lateral 

 margins, a pau* on all but anterior segments (lacking on anterior 2-30 

 or so segments). The elongated branchiae and parapodial lobes in the 

 abdominal region give an exceedingly ragged brushlike aspect to the 

 middle and posterior parts of the body. The abdominal region is often 

 extremely fragile. With or without subpodal lateral papillae or acces- 

 sory flangelike lobes (sometimes referred to as ventral cirri). With or 

 without subpodal ventral or stomach papillae or ventral fringe. 

 Setae all simple, of various kinds: capillary, crenulate or spinous 

 setae ; forked setae with frayed inner prongs (broken spinous crenulate 

 setae?; fig. 746); slender crotchets (worn spinous setae?); stout crot- 

 chets (fig. 74c) ; hastate spear-shaped or lanceolate spines. The setae 

 and crotchets may be variously ornamented with cross ridges, appear- 

 ing to be excavated or camerated or with fine transverse rows of teeth. 



Prostomium conical, more or less acutely pointed, globular, or 

 broad, spatulate, without appendages, with or without 2 small eyes, 

 with a pair of inconspicuous ciliated slitlike nuchal organs (when 

 everted, may be mistaken for minute antennae). First 1 or 2 seg- 

 ments apodous and achaetous, without tentacular cirri. Pygidium 

 simple or lobed, with 2 to 4 anal cirri. Sometimes with interramal 

 cirri (fig. 76 J,(j), interramal cushionlike ciliated lateral organs, or 

 metameric statocysts. Proboscis eversible, unarmed, simple saclike 

 or voluminous, weakly lobulated to much branched soft sac (fig. 7Qd) . 



The orbiniids are small to moderately large in size, occurring from 

 the littoral zone down to considerable depths. Aided by the pro- 

 trusible proboscis, they burrow in sand or mud containing organic 

 debris, upon which they feed. They hve upon small organisms and 

 often ingest much foreign matter, their intestines frequently con- 

 taining sand and debris of shells, foraminiferans, etc. Often very 

 coarse sand forms the chief contents of the digestive tract. They are 

 freely moving in habit and construct no tube. When removed from 

 their burrows, they usually throw themselves into close spiral coils. 

 Swimming is accomplished with an abrupt opening and closing of the 

 coil. They are noted for their fragileness. They are usually pale 

 orange to yellowish orange, orange red, with bright red branchiae and 

 postsetal lobes, due to the red blood within. 



