CIRRATULIDAE. 371 



The setae are mostly simple, capillary, or aciculiform, rarely composite 

 (Acrocirrus). Commonly capillary setae and crochets occur in the notopodia, 

 while usually shorter capillary setae and crochets, or crochets alone, may occur 

 in the neuropodia. 



Mostly long and filiform branchiae, which are contractile, occur in a dorso- 

 lateral position on a variable number of somites. 



The proboscis is always unarmed. 



Epitokous forms are frequent in the genera of the subfamily Dodecaceriinae, 

 established below, but are not known in those of the Cirratulinae proper. Some 

 species develop both smaller, pelagic, epitokous forms and larger, sedentary, epi- 

 tokous forms, as Caullery and Mesnil in their brilliant work on epitoky in this 

 family have so thoroughly demonstrated for Dodecaceria concharum Oersted.^ 

 In the epitokous stage, as also observed so frequently in other families having 

 similiar pelagic forms, the notopodia tend to develop very long and fine nata- 

 tory setae. Modifications in the eyes and in the musculature have also been 

 observed, e.g., in D. concharum. In the epitokous stage in Dodecaceria the 

 palpi tend to atrophy and the forms then may for the time conform nearly 

 to the definition of Cirrineris Blainville. Mesnil and Caullery find D. concharum 

 in its first or ordinary form to be parthenogenetic. It is in this stage also vivipa- 

 rous. Viviparity has also been detected in Cirratulus chrysoderma Claparede. 

 Some species formerly described as belonging to Grube's genus Heterocirrus 

 are shown to have been based on stages of Dodecaceria {e.g., Heterocirrus saxicola 

 Grube and H. fimbriatus Verrill, being epitokous phases of Dodecaceria con- 

 charum Oersted). 



The cirratulids live mostly in or near the littoral region though occasion- 

 ally descending to as much as 1,250 fathoms, as in the case of Chaeiozone bentha- 

 liana Mcintosh of the Challenger expedition. They live by preference in 

 muddy sand and are frequently found in slime of a putrid odor. Dodecaceria 

 concharum takes its specific name from the fact that it frequents burrows in 

 calcareous rocks and particularly old and broken shells; it also occurs in the 

 calcareous Algae, such as Melobesia and Lithothamnion,^ and bores even in sand- 

 stone. This species is frequent in oyster shells. The alimentary tract of cirrat- 

 uUds has been found to contain mud in which are noted fragments of such 



' See Mesnil and Caullery, Siir I'existence dcs formes cpitoques chez les annolides dc la faniille dos 

 Cirratuliens, Compt. rendus Acad, sci., 189G, and, more part.ieularly, Les formes epitoques et revolution 

 des cirratuliens, Ann. Univ. Lyon, 1898, p. 189. 



^Cf. Gravier, Nouv. arch. Mus. hist, nat., 1908, 10, p. 151, and Mcintosh, British annelids, 19ir), 

 3, pt. 1, p. 25G, 257. 



