NO. 1 HARTMAN : POLYCHAETOUS ANNELIDS 79 



The first few setigers are about equally long, but they increase in width 

 farther back. The first parapodium is larger than the others, directed 

 laterally or slightly forward. The dorsal cirrus of the first setiger is long- 

 er than the other lobes but slightly less so than the corresponding cirrus 

 of the second setiger. Its postsetal lobe is elongate, triangular, about % 

 as long as the dorsal cirrus; the ventral cirrus is about as long and has 

 similar proportions. The second setiger greatly resembles the first but is 

 slightly smaller and its dorsal cirrus a little longer than that of the first. 

 The dorsal cirri increase gradually in length farther back but are slen- 

 derer, and the postsetal lobe is gradually shorter, less acute (pi. 3, fig. 

 67). Ventral cirri are cirriform through only 2 segments, thereafter 

 padlike. 



From the sixth setiger branchiae are present with one filament; they 

 are slightly shorter than the respective cirri. On the next 3 segments there 

 are 2 filaments in each branchia, 3 filaments on the tenth, increasing 

 gradually to 8 or 9 filaments in the region of about the fifty-fifth segment. 

 The filaments are pectinately arranged on the branchial stem, the distal- 

 most branches are typically much shorter than those near the middle; 

 the branchial stem is broad, flat (pi. 3, fig. 71). Most of the segments 

 through median and posterior regions have well-developed branchiae ; the 

 fiftieth segment from the end still retains 4 filaments, but thereafter their 

 number rapidly falls of?; they are absent from most of the segments 

 farther back. The postbranchial region is short because the segments are 

 rapidly and increasingly shorter and narrower. 



Anterior parapodia are provided with incompletely articulate, tri- 

 dentate hooded hooks (pi. 3, fig. 69). The first setiger has 5 such hooks 

 and all resemble one another in size and shape ; there are also 5 or 6 nar- 

 rowly bilimbate pointed setae and 3 }^ellow, tapering, pointed acicula. In 

 some specimens pectinate setae are already present in the prebranchial 

 segments, but in the type none were seen before the sixth setiger. In the 

 tridentate hooks of the first few segments, the distal tooth is always the 

 longest and largest; the lowest tooth is the smallest (pi. 3, fig. 69). A 

 third parapodium is provided with a superior fascicle of 4 or 5 slender 

 limbate setae, 4 tridentate hooks, and sometim.es a few pectinate setae in 

 addition to the projecting acicula. By the fourth setiger all of these hooks 

 are replaced by pointed, simple, limbate setae except for one stout, simple, 

 tridentate hook (pi. 3, fig. 70). This acicular hook can be followed in 

 the middle part of the setal fascicle through the tenth setiger; thereafter 

 it is absent. Composite spinigers have not been found. 



Subacicular hooded, bidentate hooks (pi. 3, fig. 75) are first present 

 from the twenty-sixth setiger (in some specimens, not until the thir- 



