CAPITELLIDAE. 463 



the paleae for digging their way into the sand, and also as sieves for separating 

 out the sand, enabUng the animal to select food and suitable building materials. 

 Waste material is ejected from the small end of the tube, and the peristaltic 

 movements of the animal within the tube create a current necessary for respira- 

 tion. Amphictenids are not, as sometimes stated, exclusively nocturnal in 

 habits, but continue their digging operations in the daytime. They move 

 about actively through the mud and sand. (Watson, Ann. mag. nat. hist., 1894, 

 14, p. 43). 



Key to Genera. 



a. With two pairs of branchiae; fifteen or seventeen pairs of fasciae of capillary setae. 



b. The supraoral membrane, or velum, entire, not marginally laciniate; uncinigerous pinnulae begin- 

 ning on the third setigerous somite, fourteen pairs Pclla Malmgren. 



66. The supraoral prostomial velum with border laciniate; pinnulae beginning on the fourth setig- 

 erous somite, twelve or thirteen pairs, 

 c. With but twelve pairs of pinnulae. 



d. Fifteen pairs of f.asciae of capillary setae, all about equally developed; uncini with 6-7 equal 



major teeth, the minor ones none, or inconspicuous Lagis Malmgren. 



dd. Seventeen pairs of fasciae of capillary setae; uncini with three unequal major teeth, the 



minor teeth three or four, moderate or inconspicuous Cislenides Malmgren. 



cc. With thirteen pairs of pinnulae. 



d. Posterior dorsal margin, or ridge, of head entire; major teeth of uncini seven or eight; tube 



straight Pcctinaria Lamarck. 



dd. Posterior dorsal margin.al cephalic ridge serratodentate ; major teeth of uncini six; tube 



moderately curved Amphidene Savigny. 



aa. With three pairs of branchiae; eighteen pairs of fasciae of capillary setae Scalis Grube. 



CiSTENiDES Malmgren. 



Ofvers. K. vet. akad. Ffirh., 186.5, 22, p. 3.58. 



CiSTENIDES GRANULATA (Linne). 



Syst. nat. ed. 12, 1767, 1, p. 1268; Malmgren, Ofvers. K. vet. akad. Fiirh., 186.5, 22, p. 359. 

 Amphitrite auricoma Fabricius, Fauna Grocnlandica, 1780, p. 289. 

 Amphilrite escrichti Rathke, Nova acta Acad. Leop.-Car., 1843, 20, p. 219. 

 Pcctinaria groenlandica Grube, Fam. anncl., 18.51, p. 82, 138. 



Locality. An incomplete specimen in bottle with two specimens of Nereis 

 pelagica labeled simply Albatross, 1886. Probably from coast of southern 

 New England. 



Capitellidae. 



These are worms in which the body is elongate, cyUndrical, and composed 

 of numerous somites. The body is divided into two regions more or less sharply 

 marked off, a shorter anterior region, or thorax, consisting of from nine to four- 



