264 PROCEEDINGS OF THE ACADEMY OF [April, 



Parapodia all small and little prominent, even the first, although 

 slightly enlarged and somewhat modified as in other species, presenting 

 none of the extreme modifications so often exhibited. The first has a 

 low presetal and a much enlarged postsetal lip, the latter being broad 

 and flat at the base. Both cirri arise far out and the notocirrus is 

 tapered and reaches much beyond the end of the postsetal lobe; 

 neurocirrus bluntly truncated and falls short of the tip of the latter. 

 The second (PL XVII, fig. 51) and third differ chiefly in the shorter 

 base, shorter and broader postsetal lobe, shorter neurocirrus and 

 successively more dorsal position. With the fourth (fig. 52) the 

 parapodia have about reached the dorsal position characteristic of 

 this species and the neurocirrus has been lost in a low rounded infra- 

 podal glandular swelling. The postsetal lobe continues to shrink, 

 and by XV is quite inconspicuous and little longer than the presetal 

 lip; the neuropodium becomes a broad, low, conical eminence (fig. 53) 

 and the notocirrus, although gradually reduced in size, remains well- 

 developed to the caudal end. 



Branchia? begin on the fourth foot (somite V) of the type, but al- 

 though this is the most frequent beginning small simple ones may be 

 detected on IV or even III of some specimens; more rarely the first 

 occurs on VI. The first gill is simple or bifilar, the former being espe- 

 cially the case when they have the more anterior origin. The single 

 filament (PL XVII, fig. 52) is erect and forms the main trunk of the 

 gill, along the lateral side of which the secondary filaments arise on 

 more posterior gills. The first few gills are no longer than the noto- 

 cirri, but they increase as the latter diminish in size, the main stems 

 often reaching to or beyond the dorsimeson. Characteristically, they 

 are erect or semi-erect and pectinate (fig. 53) with a maximum of 

 about seven filaments, though the number varies from five to nine 

 according to the size of the specimen. On the type the last gill occurs 

 on XXXVII. A cotype, on which the gills are more fully extended, 

 has the gills arranged as follows : 3 filaments on VIII, 4 on XII, 5 on 

 XIV, 6 on XV, 7 on XX-XXVlf, 6 on XXVUI and XXIX, 5 on XXX, 

 4 on XXXI and XXXII, 3 on XXXIII, 2 on XXXIV, and one on 

 XXXVI. This is about the usual distribution. 



Neuropodial acicula usually four, little tapered until near the end 

 where they taper abruptly to a slender exposed mucron, the longer of 

 which project nearly to the border of the postsetal lobe. Farther 

 back they become fewer. Notopodial acicula delicate fibers passing- 

 far into the notocirri. 



Seta? all colorless. Setse of first parapodium (PL XVII, fig. 54) 



