382 THE ANNELIDA POLYCHAETA. 



Terebella astreae Dalyell, Pow. creat., 1853, 2, p. 209, pi. 26, fig. 10. 



Naraganseta corallii Leidy, Journ. Acad. nat. sci. Philatl., 1855, ser. 2, 3, p. 144, pi. 2, fig. 46-48. 



Heterocirrus saxicola Grube, Archiv. naturg., 1855, p. 109, pi. 4, t. 11. 



Helerocirrus saxicola Marion and Bobrbtzky, Ann. sci. nat., 1875, ser. 6, 2, p. 67. 



Heterocirrus fimbriatus Verrill, Check-list marine invert. Atlantic coast, 1879, p. 11. 



Locality. Off Newfoundland : Sta. 2446 (lat. 46° 20' N., long. 49° 52' W.) . 

 Depth 40 fms. Bottom of broken shells. Bottom temp. 35.5° F. The anterior 

 half of one specimen. 



Opheliidae. 



These are forms always of small or moderate size, the largest rarely exceed- 

 ing six centimeters, with the number of somites mostly between twenty-five and 

 forty. The color in life is most commonly a rose or pinkish red, due to great 

 vascularity, to which is commonly added a purplish or other hue due to irides- 

 cence at the surface of the cuticle, which is smooth and glistening. 



The prostomium not stronglj^ differentiated; either rounded in front or 

 conically pointed, often with a median i:)rolongation or tentacle. Ciliated nuchal 

 organs are exsertile from pits located posteriorly. Eyes may or may not be 

 present. 



Peristomium without tentacular cirri, but normally setigerous and often 

 with setigerous papillae. 



The somites in general are subdivided into a number of distinct annuli; 

 rarely the somites are not superficially divided ofT from each other. In some 

 genera eyes occur along the sides of the body, also peculiar segmental sensory 

 pits. 



The parapodia are not conspicuously developed. They are structurally 

 biramous, though the notopodial and neuropodial setae sometimes are merged 

 into a fascia essentially single. Setigerous papUlae either present or absent. 

 Notocirri sometimes absent, but more commonly present as branchial organs, 

 and either occurring over essentially the entire length, or else restricted to one 

 region, — anterior, posterior, or mecUan. Neurocirri may also be present, but 

 are more frequently absent or aborted. 



The setae are all capillary and simple. They may be wholly smooth, 

 limbate, or serrulate. Often they are rudimentary over part or all of the body, 

 and rarely not superficially evident. 



The nephridia occur in a considerable number of somites of the posterior 

 region as pau-ed tubules with open, ciliated, internal funnels and opening exter- 

 nally by nepliridioiDores, as usual. 



