174 THE ANNELIDA POLYCHAETA. 



more ventral one the larger. (Plate 19, fig. 7). Into the dorsal branch extends 

 a fascicle of acicular fibrillae, none of which protrudes from the surface. The 

 capillary setae are numerous, long and slender, and distally narrowing to a 

 very fine, acute and curved tip. 



Locality. Gilbert Islands : off Apaiang. Surface by electric light. Sur- 

 face temp. 84° F. 3 January, 1900. Three specimens taken. 



It is barely possible that this may be the female of A. obliquatus described 

 above, but whether this is so can be satisfactorily determined probably only 

 from material that will make possible a tracing of the sexual buds from the 

 stalk. The two forms resemble each other in the general structure of the setae, 

 though differing in finer details, and in having alike six somites in the anterior 

 region bearing only composite setae; but they differ widely in all other respects. 

 A very characteristic feature of this form is presented by the typical parapodia 

 in having two divisions strongly marked and well separated and divergent. 



Syllis Savigny. 



Descript. Egypte. Hist, nat., 1809 (= 1822), 1, pt. 3, p. 43; Grube, Archiv. naturg., 1850, 16, p. 309; 



Ehlers, Borstenwiirmer, 1864, p. 220, 222; Langerhans, Zeitschr. wiss. zool., 1879, 32, p. 526; 



Malaquin, Recherches sur les sjdlidiens, 1893, p. 71; McIntosh, British annelids, 1908, 2, pt. 1, 



p. 188. 

 Lycastis Savigny, Op. cit. 1809 [ = 1822], 1, pt. 3, p. 45. 

 loda Johnston, Ann. mag. nat. hist., 1840, ser. 1, 4, p. 231. 

 Lalage F. Muller, Archiv. naturg., 1858, 24, p. 211. 

 Gnathosyllis Schmarda, Neue wirbellose thiere, 1861, 2, p. 69. 

 Trichosyllis Schmarda, Ibid., p. 73. 



Pagenstecheria Quatrefages, Hist. nat. anneles, 1865, 2, p. 40. 

 Aporosyllis Quatrefages, Op. cit., 1865, 2, p. 87. * 



Chaclosyllis Malmgren, Annulata Polychaeta, 1867, p. 44. 



This genus was divided by Langerhans {Oj). cit., 1879, 32, p. 527 ff.) into 

 four subgenera on the basis of the character of the setae. 



Key to Subgenera. 



a. Setae all simple HaplosyUis Langerhans. 



aa. Setae in part or exclusively composite. 



h. Setae all composite, varying but little in size TiipnsyUis Langerhans. 



6?^. Simple setae also present or else composite setae of very different form or size. 



c. In addition to the composite setae in all somites there are very different simple or composite 



setae Ehlcrtiia Langerhans.^ 



Hc. Setae of the posterior somites comjjosite, those of the middle or of the middle and anterior 

 somites simple .S'y//i's Savigny sens. str. 



' The subgenus Langerhansia later added by Czerniawsky (Bull. Soc. imper. nat. Moscow, 1881, 46, 

 no. 2) is regarded as synonymous with Khlersia. 



