486 PROCEEDINGS OF THE ACADEMY OF [May, 



an incomplete transverse fracture or joint near the outer end and a 

 strongly hooked tip with a stout subterminal spur; the guard extends 

 somewhat beyond the terminal hook, and in the larger uncini at least 

 reaches far down the shaft, along which its margin is distinctly free 

 and denticulated. They are arranged in three groups, a ventral of 

 two small and slender uncini (PI. XXXVII, fig. 2), a middle of one 

 large stout (PI. XXXVII, fig. 1) and three to five smaller ones, and a 

 dorsal group of one or two which are usually longer, especially in the 

 end piece, than any of the others and intermediate in thickness. 

 The more slender uncini, as shown in the ventral one figured, have the 

 guards more prolonged. Of the simpe setae (PI. XXXVII, fig. 3) there 

 are but one or two in each foot, and they arise just dorsad of the pos- 

 terior row of uncini, the longest one reaching nearly or quite to the 

 tip of the posterior lobe and nearly equalling in diameter all but the 

 very stoutest uncini. They are colorless, translucent, have barely 

 visible oblique striations, become increasingly curved toward the tip, 

 and when perfect are terminated by a small flexible filament. 



On the tenth and succeeding parapodia the character of the setae 

 is altogether changed. There are no uncini, but in their place a spread- 

 ing ventral vertical row of rather stout pale yellow strongly striated 

 setae, four to six in number, with the outer ends broadened, flattened 

 and rather strongly curved and tapered to a very acute point (PI. 

 XXXVII, fig. 4). Dorsad of the postsetal lobe is a compact horizontal 

 row of more numerous, longer, narrower and straighter setae of other- 

 wise similar form and structure. At the base of these, on the dorsal 

 side, is a group of a few colorless spatulate setae with slender stems 

 and abruptly broadened fork-shaped ends with seven tines (PL 

 XXXVII, fig. 5). 



By the thirty-fifth parapodium the setae are practically all confined 

 to the horizontal dorsal fascicle and the spatulate setae are more 

 numerous, and have broader more curved plates with as many as nine 

 rather spreading tines. Among them are also a few very small spatu- 

 late setae with ovoid blade and simple mucronate tip. Posteriorly 

 the setae, especially the simple ones, are reduced in number, become 

 more slender and project far beyond the now very small ventro-caudal 

 lobe. By the seventy-fifth parapodium only about six such setae 

 remain, and the spatulate setae have continued to widen and bear as 

 many as eleven times. Still further caudad the number of setae is 

 further reduced and they become more slender. 



The four anterior parapodia are each supported by about three 

 slender aciculi which enter the base of the dorsal cirrus, and the same 



