DODECACERIA CONCHARUM. 381 



segment; they form a band across the dorsum, with the filaments more closely 

 crowded laterally. 



The upper and lower fasciae of setae are separated by a moderate space, 

 the distance between them in the type being only .6 or .7 rrmi. 



The tubercles are weak and do not arise from any distinct ridge such as 

 occurs- in many species {e.g., C. megalus). 



Spines occur in most of the ventral fasciae. They are proportionately 

 stout and their apices project freely but a short distance. In each fascicle there 

 are three, or less commonly, four spines. They occur well forward, but the seg- 

 ment on which they first appear could not be determined with certainty. (Plate 70, 

 fig. 5). The spines of the notopodia are paler and more slender, and are more 

 numerous in each fascia. The capillary setae relatively long. (Plate 70, fig. 6). 



Locality. Easter Island: 20 December, 1904. Shore. One specimen. 



Audouinia filigera Delle Chiaji is used here as by Ehlers (Abh. K. gesellsch. 

 wiss. Gottingen. Math. phys. klasse, 1901, p. 183), to include also A. lamarckii 

 Audouin and Milne Edwards (1840). Other synonymous names are australia 

 Gay (1859) and chiajei Marenzeller (1888). The unsatisfactory condition of the 

 classification of this and related genera makes it difficult to determine species, 

 in the absence of extensive material, from the literature. The large number of 

 somites proportionately to length in the present form is noteworthy. It seems 

 to differ from the species also in coloration and in proportions. A. filigera is 

 common along the Chilean and Patagonian Coasts, as well as in the Atlantic. 

 Ehlers did not find any Chilean or Patagonian specimen having the dorsal 

 branchiae inserted on the seventh somite as in the present form, though such 

 occur in the Atlantic (lamarckii). St. Joseph (Ann. sci. nat., 1894, ser. 5, 17, p. 51) 

 notes variations in this respect. Marenzeller (Zool. jahrb. Syst., 1888, 3, pt, 1, 

 p. 16) records a form of this species, variety meridionaUs, from Angra Pequena 

 Bay. 



DoDECACERiA Oersted. 



Annulatorum Danicorum conspectus, 1843, p. 44; Mesnil and Caullery, Ann. Univ. Lyon, 1898, 



p. 116; McIntosh, British annelids, 1915, 3, pt. 1, p. 254. 

 Heterocirrus Grube, Archiv. naturg., 1855, 21, p. 108. 



Dodecaceria + Heterocirrus Quatrefages, Hist. nat. annelcs, 1865, 1, p. 465 (in part). 

 Naraganseta Leidy, Journ. Acad. nat. sci. Philad., 1855, ser. 2, 3, p. 144. 



Dodecaceria concharum Oersted. 



Annulatorum Danicorum conspectus, 1843, p. 44, fig. 99; Me.snil and Caullery, Ann. Univ. Lyon, 



1898, p. 5, pi. 1, 2; McIntosh, British annelids, 1915, 3, pt. 1, p. 255. 

 fNereis sextentaculata Delle Chiaji, Mem. anim. regn. Napoli, 1828, 3, p. 176, pi. 43, f. 16. 

 Cirratvlus concharum Grube, Fam. annel., 1851, p. 68. 



