276 U.S. NATIONAL MUSEUM BULLETIN 227 



rounded anteriorly, slightly flattened dorsoventrally, with 4 eyes (2 

 reported for type) in transverse row on posterior border (fig. 73a). 

 Parapodia (fig. 736) with small but distinct notopodia with embedded 

 acicula, with prominent neuropodia. Neuropodia with short rounded 

 setal lobe and elongated cirriform postsetal lobe containing a vascular 

 loop; 1-3 stout amber-colored projecting acicular setae (fig. 7dd) and 

 simple curved limbate setae with acute tips and finely denticled 

 margins (fig. 73c). 



Proboscis with mandibles dark, wing-shaped (fig. 73,e,h). Max- 

 illae (fig. 7Sj,g,i) with pair long slender maxillary carriers and rather 

 short unpaired piece (latter not shown in figure). Maxillae i and ii 

 asymmetrical. Right maxilla i longer than left, with up to 10 den- 

 ticles along length of inner border and without distal hook; left 

 maxilla I with up to 6 basal teeth and distinct distal hook (Moore, 

 in figure for type, showed distal hooks on both first maxillae and 

 fewer teeth, fig. 73i), Left maxilla ii much larger than right maxilla 

 II, completely overlapping left maxilla i and extending down to 

 maxillary carriers, with up to 12-13 teeth; right maxilla ii partially 

 overlapping right maxilla i, with up to 8-10 teeth. Maxillae iii 

 each with six teeth. Maxillae iv each with 5 teeth. Maxillae v 

 each with a single tooth (may appear to blend in with maxillae iv). 



Biology. — Found at low water and dredged on bottoms of sand 

 with shells. StifT and wiry. Young stages of this species thought 

 to live parasitically in the body cavity of Diopatra cuprea (Pettibone, 

 1957b). How and at what stages they enter and leave the host are 

 unknown. Found living parasitically from a small stage of 7 segments 

 up to elongated worms of up to 200 segments and 5 mm. long (Allen, 

 1952). More than 50 parasites found in a single host. 



Material examined. — Free-living specimens from Massachusetts 

 (Buzzards Bay, H. Sanders; Nantucket Sound, 8 fathoms, T. Shafer, 

 numerous specimens), Maryland (Isle of Wight Bay above Ocean City, 

 S. McDowell), Virginia (off Cape Henry, Fish Hawk Station 8838, 9 

 fathoms, 1920), North Carolina (Beaufort, E. Cole). Parasites in 

 Diopatra cuprea from Massachusetts (Hadley Harbor, Nonamesset 

 Island, J. Allen; Nantucket Sound, 8 fathoms). 



Distribution. — Massachusetts to North Carolina. Low water to 

 9 fathoms. 



Family Orbiniidae ( = Ariciidae) 



Body long, slender, vermiform, with moderate number or very 

 numerous segments (60-300); segments often biannulate or triannu- 

 late. Parapodia biramous, supported by acicula. Body divided 

 into 2 weakly to sharply separable regions: (1) Shorter anterior thor- 

 acic region, more or less flattened dorsoventrally and enlarged, firm, 

 muscular, attenuated anteriorly, with biramous parapodia which are 



