308 PROCEEDINGS OF THE ACADEMY OF [April, 



posterior region somewhat depressed, relatively shorter and more 

 crowded than anteriorly and gradually tapered to the caudal end. 



Pygidium a minute wing bearing a pair of long, very slender, flagelli- 

 form subanal cirri at least equal to the greatest width of the body, 

 including the parapodia, and often one-third longer. 



Parapodia situated near the ventral level anteriorly, extending 

 their entire depth on most of the posterior region, all long and slender, 

 those at the anterior end of the anterior region and throughout the 

 posterior region equalling the width of the segments or, near the caudal 

 end, exceeding them. As far as somite XXIX they are uniramous. 

 The first foot (fig. 160) is small, with a minute setigerous tubercle 

 nearly concealed between the much longer dorsal and ventral cirri. 

 Succeeding ones gradually enlarge and the next few have the neuro- 

 podium divided into presetal and postsetal lobes of nearly equal length, 

 the former broad and with an axial prolongation, the latter narrow 

 and tapered (fig. 160). Dorsal and ventral cirri are about one-fourth 

 longer than the neuropodium, moderately slender and tapered to 

 blunt points, the former with a pitlike depression and glandular 

 swelling near the base, beyond which it is bent somewhat abruptly 

 dorsad, the latter nearly straight. On still succeeding somites all 

 parts of the parapodium become increasingly compressed and foliaceous 

 and the neuropodium longer than or at least equal to the cirri. On 

 typical parapodia of this region (PI. XXI, fig. 162) the broadly ovate 

 postsetal lip is longer than the presetal lip, which is broadly obcordate 

 petalliform with a tongue-shaped prolongation arising from the sinus. 

 Neurocirrus about as long as neuropodium, compressed, of nearly 

 uniform width to near the bluntly triangular tip. Notocirrus always 

 irregular and somewhat distorted in outline, the base somewhat 

 contracted, the distal part subovate, somewhat foliaceous and more 

 or less abruptly bent dorsad. 



At somite XXX a small notopodium appears abruptly anterior to 

 the base of the notocirrus and immediately consists of a small setig- 

 erous tubercle, a short presetal lip and a longer postsetal lip. Through 

 the remainder of the anterior region the biramous parapodia undergo 

 no marked change, but with the beginning of the posterior sexual 

 region (about somite LXX to LXXVI) they become distinctly larger 

 and the rami better differentiated. Typical parapodia of this region 

 (fig. 163) are large and deep with the neuropodium much exceeding 

 the notopodium, compressed, somewhat widened distally into a broadly 

 rounded acicular tubercle enclosed between broadly foliaceous, more 

 or less irregularly ovate, presetal and postsetal lips, of which the 



