298 THE ANNELIDA POLYCHAETA. 



finally disappears at about the sixteenth parapodia. The parapodia from the 

 fourth on are attached near the middle of length of somite and are shifted farther 

 dorsad, as usual. 



All branchia are simple unbranched filaments which are mostly more or 

 less flattened. The first branchiae detected are on the fourteenth parapodia 

 in both specimens ; they are shorter than the notocu-ri, are a little tapered distad, 

 but with the distal end not acutely pointed. Branchiae of similar form continue 

 to be present on all the following parapodia to the end. They may become, 

 in some cases, a little longer than the cirri, but in no case exceed half the dis- 

 tance to the middorsal hne, usually falling distinctly short of half the distance. 

 (Plate 43, fig. 7). 



The ventral acicula are moderately stout structures, the exposed distal 

 portion of which terminate in a fine, short, curving tip. (Plate 42, fig. 6). The 

 setae of the dorsal group are long. For most of their length they are straight 

 and capillary, but toward the distal end each is bent. On each side in the region 

 of the bend broadened by two distinct Umbi or wings and distally narrowed to 

 a long fine tip. (Plate 42, fig. 5). There is a ventral group of similar hmbate 

 setae on all but the anterior parapodia. The ordinary crochets, two in num- 

 ber in each parapodium, are long and much exposed, and of uniform width over 

 most of their length; at the distal end bidentate, both teeth bent out at right 

 angles to the general axis and the distal one the smaller; membranous guard 

 shghtly exceeding the teeth, the distal edge straight and rising obliquely from 

 near the lower tooth to above the upper one; strongly fibrillate distad to the 

 cervix. (Plate 43, fig. 2). The pectinate setae are short, deUcate, and trans- 

 parent ; the expanded distal end is rolled in the form of a hollow cone, with a 

 sector of about one third missing. The distal margin fringed and the ends each 

 angularly extended mesad into a characteristic triangular flap. (Plate 43, 

 fig. 1). The crochets of the first parapodia are of about the same proportions 

 as those of the other regions of the body, but they present a strong joint and 

 the teeth are of different shape and proportions, the distal one being much 

 the larger, the subapical one much reduced; the joint is very obhque and 

 situated well distad. (Plate 42, fig. 4). On the fourth foot the compound 

 crochets have been replaced by simple ones, one to each parapodium, in 

 which the teeth are of somewhat intermediate character. The dorsal setae in 

 the anterior parapodia are strongly limbate and bent, as elsewhere, but are 

 apparently shorter. 



The maxillae are thin and translucent, darkened along some of the edges 



