24 LEODICip^ OF THE WEST INDIAN REGION. 



than the ventral. The sets are in a dense tuft and there is a dark-brown acicula which 

 may not protrude to the surface at its outer end. A small tuft of needle aciculse extends 

 into the base of the dorsal cirrus. The tenth parapodium (text-figure 42) is thick, so 

 that a cross-section of its seta lobe would be nearly circular. The posterior lip of the 

 parapodium is shghtly longer than the anterior and the two are continuous with one 

 another in such a way as to leave a shallow groove between the lips and the rounded end 

 of the lobe. On the dorsal surface of the lobe is a palp-like lip which overhangs the bases 

 of the setae and the single large acicula protrudes from the surface just ventral to this 

 lobe. The dorsal cirrus is elongate-lanceolate in form with a constricted base and tuft 

 of needle aciculse. The ventral cirrus is roughly triangular with a rounded apex at the 

 end of a very thick ventral pad. This pad-like structure appears first on the fifth somite 

 and extends throughout the greater part of the body. 



The ninety-seventh parapodium (text-figure 43) shows very little distinction be- 

 tween the anterior and posterior lips, and has ventral aciculse in addition to the dorsal 

 ones comparable to those found farther forward. The dorsal cirrus is long and slender, 

 smaller than the gill filaments which arise from it. The ventral cirrus is short and thick 

 at the end of the ventral pad. Later parapodia are conical in outhne (text-figure 44), 

 with prominent, slender, dorsal and ventral cirri, the former with a small gill-filament. 

 The needle aciculse and the two sets of large aciculse mentioned earlier also appear. 



There are two pairs of anal cirri (plate 3, figure 4), the ventral ones much smaller 

 than the dorsal. 



The setae of the first parapodium are of the usual three forms. The simple setse 

 (text-figure 45) are slender, very gently curved, with a well-marked wing along the 

 concave and a smaller one along the convex margin. The compound setse (text-figure 46) 

 have stout basal portions with their apices broadened and obliquely striated; the ter- 

 minal portion of each is slender, with apical and subapical but no basal tooth, and is 

 covered by a striated hood. The setse of later somites, through elongation of their basal 

 portions, are carried much farther from the body than in the first, and toward the pos- 

 terior end of the body extend as far as the apex of the dorsal cirrus. The simple setae 

 are more curved and the wing along the convex edge is more sharply expressed than in 

 the first somite. The compound setse (text-figure 47) have a relatively shorter but 

 absolutely longer terminal portion, whose whole contour is more sharply expressed than 

 in the first somite. The subapical tooth is larger and a basal knob is present. The 

 pectinate setse (text-figure 48) are similar throughout, with about ten well-marked 

 teeth, the terminal ones equal and longer than the others. 



The dorsal aciculse (text-figure 49) are rather heavy, dark brown in color, but lighter 

 at the apex, which is bifid, the dark-brown central portion extending into only one of the 

 branches. The ventral aciculse (text-figure 50) are much more slender with bidentate 

 apex covered by a striated hood. 



The maxilla is dark brown, washed by a whitish incrustation. The carrier is short, 

 with relatively large wings on the sides. The forceps is large, with slender halves very 

 dark brown in color. The right proximal plate has 4 teeth, the left has 5; the right 

 paired plate has 6, the left has 2. The unpaired plate has 6 teeth (text-figure 51). All 

 of the plates are dark in color with the apices of the teeth marked with white. Beyond 

 the distal plates are light-brown chitinous patches. The mandible is short and thick, 

 the basal halves well separated and dark in color. The beveled portion is covered 

 with a whitish incrustation and is marked with concentric brown lines (text-figure 52). 

 Anterior to this beveled portion is a thin, whitish expansion on either side. 



This species was collected in the Dry Tortugas in considerable numbers, living in 

 parchment-like tubes which followed the windings of the cavities of sponges. These 

 tubes are much branched (text figure 53) and have at intervals blindly ending passages. 



