CENOTHRIX. 329 



Cenothrix, gen. nov.^ 



Prostomium subcorneal or ovoid, smooth, devoid of tentacles or palpi. 



Body elongated, with numerous distinct segments, tapering both anteriorly 

 and posteriorly. 



First and second somites lacking parapodia and setae. Nuchal processes 

 not evident. 



Parapodia essentially unii'amous, the notopodium reduced to a slight 

 tubercle. Ending in a finger-like, postsetal process, but with no presetal process. 



All setae simple, partly limbate, and partly of the stout, crochet type 

 wdth membranous guards, but the latter without teeth or hooks. Limbate 

 setae in all parapodia and one crochet in each parapodium excepting the most 

 anterior. Setae in type-species few and largely definite in number. 



Five pairs of maxillae. The carriers of the first pair extended caudad into 

 long, slender, tendon-Uke processes, the plates dentate, unequal. Maxillae II, 

 III, and IV dentate and unequal. Maxillae V reduced to simple hooks. Man- 

 dibles mesally in contact in the broad anterior region, the stems short and scarcely 

 narrowed caudad. 



Genotype. — Cenothrix mutans, sp. nov. 



In the characters of the jaws this genus falls into Grube's Eimicea Priog- 

 natha of group B (Jahresb. Schles. gesellsch., 1879, 56, p. 80), including Drilon- 

 ereis, Arabella, etc., but it differs in having setae of two main types, in which 

 respect it agrees with genera of his group A. The crochets, however, are of a 

 peculiar structure and, furthermore, do not increase in number caudad and in 

 the posterior region occur to the exclusion of the limbate type. Thus it differs 

 from LarjTnna Kinberg (Zygolobus Grube), e.g., in the greatly elongate, spine- 

 like, stems of maxillae I, in the edentate character of the crochets, and in the 

 uniform distribution of limbate setae on all parapodia ; and, on the other hand, it 

 differs at once from Ai'abella in having setae of the crochet-type at all. It is, I 

 beheve, close to Notocirrus Kinberg, the tyj^e of which also comes from the South 

 Pacific region; but, particularly in view of some uncertainty in regard to import- 

 ant details in the type of Notocirrus, I have felt it necessary to keep the forms 

 apart. The spine construed by Schmarda as a hooded crochet in his type- 

 species differs from that in Cenothrix in being distally bidentate and in the much 

 smaller, rounded membranous guards. 



' Kawos, new, strange, and epi|, bristle. 



