1903.] NATURAL SCIENCES OF PHILADELPHIA. 425 



nor cilia, but the interior is apparently divided by delicate plates into 

 irregular polygonal cells, the largest of which are marginal. 



Four forms of setae occur on typical somites (X). Those of one 

 kind are colorless, long, slender, curved and tapering, bear rather dis- 

 tant opposite pairs of slender awn-like spines, and have slightly enlarged 

 bases not shown in the drawing (fig. 24) ; these are arranged in a single 

 long vertical row which extends nearly half-way down the anterior face 

 of the foot, and are attached to the notopodial fold which largely covers 

 them anteriorly; they do not occur caudad of XX. Behind these is 

 a second vertical row of stouter colorless spines, slightly enlarged sub- 

 terminally and then tapering and fringed; few perfect examples of 

 these have been found and none occur as far caudad as XXVI, and still 

 farther back the first-mentioned capillary set® are also wanting. A 

 third vertical row contains seta? of two kinds and, with certain changes 

 in number and arrangement, is constant on all parapodia. Five or six 

 pale yellow, short, stout setse occupy the dorsal end of the bundle in 

 more anterior, and the middle in more posterior somites; they present 

 a subterminal enlargement, and a peculiarly roughened slightly hooked 

 tip continued into a densely hairy fihform appendage and guarded by 

 a dense brush of very stiff hairs ; usually the capillary tips and much of 

 the guard have been worn away, and possibly the tip is normally absent 

 posteriorly. Ventral to these in anterior, and both ventral and dorsal 

 in posterior, somites is a group of colorless more slender setse, with 

 broad lance-shaped ends and transverse rows of fine bristles which 

 become larger on the dorsal side. 



Besides the true notopodial and neuropodial acicula, fiber glands are 

 found in relation to all parapodia from somite IV to the end of the body, 

 although the chitinoid rope is conspicuous only between X and XXV. 

 In structure they resemble very closely Eisig's figures of Polyodontes, 

 that of XVI, for example, consisting of a dense strand of chitinoid fibers 

 of iridescent brassy color, enveloped in a cellular sheath and measuring 

 15 mm. long by .3 mm. in diameter. The free internal end gradually 

 tapers, the cellular sheath at the same time becoming thickened and 

 finally terminating in a slightly bulbous mass of cells, from v/hich the 

 gradually forming fibers may be traced. The outer end presents a 

 rather considerable spherical enlargement of al^out twice the diameter 

 of the strand and composed of a dark granular matter (cells?). It is 

 attached to the integument at the bottom of the postnotopodial groove 

 from which the most anterior row of setae arises, and when forcibly 

 pulled away entire some of these come with it. The strands pass into 

 the ccelom, the anterior ones usually arranged horizontally by the 



