50 THE ANNELIDA POLYCHAETA. 



phores and dorsal cirrophores the parapodia are thicker anteroposteriorly and 

 deeper, the dorsal line rising dorsomesad while the ventral one remains hori- 

 zontal; distad of this they continue to narrow to the slight notopodial eminence, 

 beyond which the neuropodium is very slender and more uniform in thickness. 

 The neuropodium at the distal end is produced into a slender digitiform process 

 through one side of the base of which the aciculum protrudes. The notopodium 

 is a slight tubercle on the dorsal surface into which an aciculum extends but 

 which bears no setae. The ventral cirrus is attached distad of the middle of the 

 parapodium and is a small, slenderly subulate filament not attaining the end of 

 the neuropodium. The dorsal cirri are found on the parapodia of the somites 

 between those bearing elytra. In each of these beyond the swollen basal joint, 

 or cirrophore the style continues as a gradually and slenderly acuminate fila- 

 ment which reaches to or extends a little beyond the distal ends of the longest 

 setae. 



The acicula are distally a little denser or less clearly transparent than 

 proximally. The notopodial one is shorter and more slender than the neuro- 

 podial. Only neuropodial setae are present. These are of two types. On the 

 ventral side of the setigerous surface of the neuropodium is a group of stout 

 setae of ordinary length each of which ends in an asymmetrical, lanceolate head. 

 (Plate 6, fig. 5) . A little below the apex of the head is a small subapical tooth 

 and proximad of this, over the entire length of the more oblique side, is a close 

 series of ovate, lanceolate scales. Above this ventral group are setae of a sec- 

 ond type which are three or more times as numerous. These are of smaller ac- 

 tual diameter and at the same time much longer, the longest being from two 

 to three times the length of the ventrals. They are comparable in structure 

 to ventral ones imagined as greatly stretched, giving an exceedingly long and 

 slender and usually gently curved head along the convex side of which the scales 

 are correspondingly more widely separated. (Plate 6, fig. 3, 4) . In each there is 

 a small subapical tooth which seems to be easily lost. Some setae show the 

 scales along two sides, but the scales on one of the sides form only a short series. 



The elytra are all missing. Eighteen pairs of elytrophores are distinguish- 

 able in the type. The elytrophores are subcylindrical and of moderate length, 

 decreasing in diameter and length caudad. The bases of the parapodia between 

 those bearing the elytrophores are somewhat more crassate than the others. 

 The elytrophores occur on somites II, IV, V, VII, IX, and on alternate suc- 

 ceeding somites to XXIII, and then on XXVI, XXIX, XXXII, XXXIV, 

 XXXVII, and XL. 



