374 THE ANNELIDA POLYCHAETA. 



the notopodial tubercle on the anterior segment; the distance of the point of 

 insertion increases caudad, and in the middle and caudal regions approaches, 

 but does not fully equal, the distance between the neuropodial and notopodial 

 tubercles. No special branchiae can be detected in the type. Neither tentacles 

 nor scars of any can be found. 



The setigerous tubercles on each somite are widely separated, the distance 

 between them in all parts exceeding that between notopodium and point of 

 insertion of branchia (in the middle region, about 1.8 mm. instead of 1.2 mm., 

 and near the beginning of posterior third, 1.6 nmi. instead of 1 mm.). Neither 

 the setigerous tubercles nor the branchiae arise from any ridge. Where the 

 branchiae have fallen off a longitudinal furrow is seen along the line of their 

 insertions. 



The ventral spines are detected first on from the thirty seventh to the 

 thirty ninth setigerous somite, or near that region. On the more anterior somite 

 they are three in number but quickly rise in the widest part of the body to four 

 or rarely five, though somites with but three may occur between those having 

 the larger number. Caudad the number again falls to three, and this is the 

 number occurring throughout most of the body length. The most anterior 

 ventral spines are shorter and straight, or nearly so, the size increasing caudad 

 and the exposed region becoming conspicuously curved, with the concavity 

 cephalad. They are dark colored and strongly cross-striate. (Plate 70, fig. 5). 

 The notopodial spines seem to occur first about twenty somites farther caudad 

 than the first of the ventral ones. They are paler and more slender than the 

 ventral ones, and in each notopodium there are five or four, or the number rises 

 to six farther caudad on the somites that bear but three, much stouter, neuro- 

 podial spines. 



Locality. Galapagos Archipelago: Chatham Island. Shore. 18 January, 

 1904. One specimen. 



This species is distinguished from others of the group primarily by the 

 arrangement of the setae and spines, namely, in having in both series only 

 capillary setae on the most anterior, and in the others both capillary setae and 

 spines. C crassicolis (Kinberg) from near Honolulu differs, e.g., in the arrange- 

 ment of spines, in the gi-eater relative stoutness of the anterior branchiae, and the 

 fewer segments. 



CiRRATULUS Lamarck. 



Anim. s. verteb., 1801, 5, p. 300; Johnston, Cat. annelids Brit, mus., 1865, p. 209. 

 Cirrhatulus AuDouiNand Milne Edwahds, Hist. nat. litt. France. Annelidcs, 1834, 2, p. 2G8; Qu.\tre- 

 FAGES, Hist. nat. annelos, 186.5, 1, p. 454. 



