ONUPHIS LEPTA. 293 



the base about as usual; distad of the short, cyhndrical paler cirrophore it 

 expands abruptly, then narrowing gradually to a point. The neurocirrus is 

 attached, as usual, on the ventral surface at the base; it is shorter and more 

 slender than the notocirrus. The low, distally rounded setigerous lobe is not 

 extended in front of the setae, but it is produced into a slender cirriform post- 

 setal process, which is much shorter than the cirri proper, commonly not more 

 than half as long as the notocirrus. (Plate 46, fig. 3). In succeeding parapodia 

 the notocirrus continues throughout, but caudally becomes much reduced both 

 in length and thickness. The neurocirrus of the second pair is shorter than on 

 the first, and that of the third is still shorter, often appearing as a short, basally 

 stout, conical process; that of the third and succeeding parapodia appears only 

 as a flattened scale merged in a ventral glandular area. The postsetal process 

 becomes quickly reduced caudally but appears as a short subcorneal process 

 as far back as the seventh, or sometimes the eighth parapodia, caudad of which 

 it is obliterated. (Plate 46, fig. 3-8). 



The branchiae first occur on the sixth parapodiferous segment and continue 

 to the fifty third inclusive. They are in all cases simple, unbranched filaments. 

 (Plate 46, fig. 9-12). 



The ordinary acicula are proximally stout, but distally they are strongly 

 attenuated, the tip being very fine and often sinuously curving. (Plate 45, fig. 7). 

 In the ordinary somites of the middle and posterior regions there are the usual 

 types of setae. The setae of the more dorsal group are of moderate length, 

 flattened, distally more or less curved, with a fine tip, and distinctly narrowly 

 limbate. The delicate pectinate setae are relatively large; distally they enlarge 

 clavately very gradually, the expanded distal portion being comparatively long 

 and moderately narrow; the distal pectinate end is asymmetrical, rising obliquely 

 from one side to the other, with teeth apparently of uniform length. (Plate 45, 

 fig. 5). The somite at which the ordinary crochets begin in the type is the 

 eleventh (tenth parapodial). In each parapodium they are usually two in 

 number, but sometimes three occur. They are stout, rather strongly narrowed 

 just below the teeth; bidentate, the inferior tooth large, acute, straight, or with 

 the tip slightly bent downward, and projecting forward about at right angles 

 to the general axis of the crochet; the superior tooth much smaller, acute, and 

 bent forward but little. The membranous guards extend distinctly over and 

 above the inferior tooth, and a little above the upper one; the distal margin of 

 each rises slightly at the caudal end, from there running first nearly straight and 

 then toward the anterior end curving a little downward. The fine fibrillae 



