1903.] NATURAL SCIENCES OF PHILADELPHIA. 721 



besides a short, thick, biunt acicular lobe it bears a posterior and a 

 ventral lobe, both of which are bluntly conical and have their free 

 portions subequal. The ventral cirrus, borne at the base of the neuro- 

 podium, is rather thick with a constricted base, and reaches the tip 

 of the acicular lobe. 



The next two or three parapodia change quickly, and by the fifth 

 (fig. 3) the typical form is attained. The bases of both rami are longer 

 and deeper, and in the neuropodium the posterior lobe has lengthened 

 so that it reaches distinctly beyond the ventral lobe; both lobes are 

 more pointed. The notopodium exceeds the neuropodium in size 

 and complexity, having a short, posterior acicular lobe and three 

 pointed conical processes, of which the dorsal is the largest, the ventral 

 as long but more slender, and the anterior, which lies immediately be- 

 fore the fascicle of setae, much the smallest. The slender dorsal cirrus 

 is nearly as long as the dorsal lobe, from just within the base of which 

 it arises. 



In succeeding parapodia, besides a general increase in size many 

 changes in proportion of parts take place. The two rami become more 

 elongated and crowded together, as shown in the thirtieth parapodium 

 (fig. 4). Here both dorsal and ventral cirri have become much more 

 slender and reduced to a length of i or i of the parapodium, and the 

 former is carried much farther out than in preceding somites; the 

 neuropodial acicular lobe is very prominent, with a distinct presetal 

 process and bears the posterior lobe as a postsetal process, while the 

 ventral lobe has undergone little alteration beyond being more pointed. 

 The notopodium is nearly twice as deep as the neuropodium. beyond 

 which it also extends; the largely developed acicular lobe bears the 

 "pointed, now subequal, anterior and ventral lobes as presetal processes; 

 the dorsal lobe stands more apart as a broad, triangular, somewhat 

 flattened piece. Still farther caudad all of the lobes shrink in size and 

 become elevated on a longer basal region. 



Except the notopodium of the first, each ramus of every parapodium 

 contains a single aciculum which is simple, slender, tapering and color- 

 less. 



There are two kinds of setae, both having rather slender, slightly 

 curved, transparent, colorless and camerated shafts. In one form (fig. 

 8) the blades are very long, slender and acute, especially in the middle 

 region of the body, with one margin delicately fringed; the shafts, as 

 compared with the other kind, are longer, more slender and have the 

 margins of the socket of nearly equal height all around. The other 

 form (fig. 7) has the shaft somewhat stouter and more curved, the end 

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