of the Virginian Coast 



251 



POLYDORA Bo8C. 

 POLYDORA HAMATA 71. Sp, 

 PL. Vm, FIGS. 111-116. PL. IX, FIGS. 117,118. 



Head emarginate in front, outer angles rounded, directed 

 outward and forward. 



Eyes four, black, between bases of tentacles ; the anterior 

 pair larger and further apart than the posterior. 



Branchiae begin on the seventh segment, 38 pairs, short, 

 flattened, not tapering ; bluntly rounded, almost truncate 

 externally. 



There is no terminal sucker, but in its place are two 

 somewhat quadrangular lobes (f. 118), each with a short 

 lateral cirrus. Aual opening surrounded by a circle of 

 low papillae. 



Setae. On the anterior segments are the ordinary ca- 

 pillary setae, simple acuminate (f. Ill) ; after the change 

 of setae, these are confined to the dorsal rami. On the fifth 

 segment there are two kinds of setae ; in the upper series 

 from 8 to 10 stout, flattened setae, slightly curved near the 

 end, not difiering much from each other but with no two 

 exactly alike (f. 112) ; in the lower series from 4 to 6 short 

 capillary setae, for the most part Hkef. Ill, but sometimes, 

 as in f. 113, widened at outer third. 



From 15 to 24 of the posterior segments are furnished with 

 stout hooks, one to each dorsal ramus (f. 116) ; with these, 

 in addition to the ordinary capillary setae, is one much 

 longer than the rest (f. 117). The change of ventral setae 

 takes place on the 7th segment, though a few capillary 

 setae are found on that segment. The anterior ventral 

 setae (f. 114) after the change, are somewhat stouter than 

 the posterior (f. 115)^ all bidentate, covered at the end 

 with a membrane, as shown in the figures. 



The anterior part of the body is rounded below and 



