394 THE ANNELIDA POLYCHAETA. 



Savigny used the term Telethusa for this family, which is still often referred 

 to as the Telethusae, or the Telethusidae. 



Key to Genera. 



%. Branchiae appearing only in the posterior region (somite 18-21); simple, bifid, trifid or quadrifid; 



hermaphroditic; otocysts absent Branchiomaldane Langerhans. 



J. Brancliiae beginning in the anterior region, branching more complex; dioecious; otocysts usually 

 present, but in some absent. 

 b. A distinct tail present, the parapodia and branchiae not extending to the caudal end of the body; 

 prostomium well developed, trilobed; branchiae pinnate, eleven to thirteen pairs, the first 



ones appearing on the seventh setigerous somite Arenicola Lamarck. 



bb. No distinct tail, the parapodia and branchiae being continued to the caudal end of the body; 

 prostomium simple and non-lobate; branchiae unilaterally branched, of variable number, 

 the first ones appearing farther back on setigerous somite 12-16 Arenicolides Mesnil. 



Akenicola Lamarck. 



Anim. s. verteb., 1801, 5, p. 324; Gamble and Ashworth, Quart, journ. micr. sci., 1900, 43, p. 540. 

 Chwizobranchii^ Quatrefageh, Hist. nat. anneles, 1865, 2, p. 267. 

 Clymenides Clapar^de, Beobacht. anat. ent. wirbell. thiere, 1863, p. 30. 

 Pteroscolex Lutken, Vid. meddel. naturk. foren Kjobenh., 1864, p. 120. 



Arenicola ceistata Stimpson. 



Proc. Boston soc. nat. hist., 1855, 6, p. 114; G-^mble and Ashworth, Quart, journ. micros, sci., 1900, 



43, p. 432. 

 Arenicola {Pteroscolex) antillensis Lvtken, Vid. meddel. naturk. foreu Kjobenh., 1864, p. 120. 

 Arenicola antillensis Ehlers, Mem. M. C. Z., 1887, 15, p. 173. 



Locality. Florida. Albatross, 1886. 



One large specimen conforming fully to this species, which occurs along the 

 south Atlantic Coast of the United States and in the Antilles, and has been taken 

 as well at Naples. 



Flabelligeridae . 



In the members of this family the body is short, rarely exceeding seven or 

 eight centimeters in length, with the number of somites mostly limited, rarely as 

 many as ninety. The thickness of the body varies, but the general form is 

 commonly fusiform, or more swollen anteriorly. The surface of the body is 

 mostly covered with muciparous papillae, which are sometimes filamentous and 

 at others clavate, with commonly a transparent coating of mucus, to which 

 grains of sand adhere. This mucus when fresh, i.e., the outer layers of it, is 

 soluble in 5-10 per cent sodium carbonate, but not so the older, inner and col- 

 loidal layers. (Bles, Rept. Brit, assoc. 1892, 1891, p. 373). 



