1903.] NATURAL SCIENCES OF PHILADELPHIA. 465 



this species. Form as usual in the genus, depressed, flat dorsally, 

 strongly convex ventrally, stout anteriorly, and tapering into a long 

 slender fragile posterior region. This is evidently a species of con- 

 siderable size, but is represented by 3 short anterior ends and a frag- 

 ment of the posterior end. 



Head mammiform, as \dewed from above, with a dome-shaped 

 basal piece incomplete ventrally, being cut into by a low median 

 ridge which is continued to the mouth from the regularly conical 

 pointed terminal piece. Mouth ventral, a rather small sht-like or 

 sHghtly quadrate opening, bounded posteriorly by the 2d setigerous 

 somite, laterally by the lobe-like thickenings of the 1st setigerous 

 somite! and anteriorly by the caudal end of the prostomial ridge; its 

 four angles are prolonged into chinks passing into the furrows bounding 

 the 1st setigerous somite, which is incomplete ventrally, and between 

 the oral lobes of which the second setigerous somite is produced as a 

 wedge-shaped hinder hp. 



Parapodia biramous throughout, the first 16 relatively low, with very 

 broad attachment on lateral faces of somites; both notopodia and 

 neuropodia with broad, more or less pectinate postsetal lobes, the latter 

 much the better developed; posterior to the 18th the parapodia are 

 entirely dorsal, the fimbriated postsetal lobes are replaced by simple 

 ones, and the neuropodium is rudimentary. The 10th parapodium, 

 which is typical of the anterior region, exhibits the following characters : 

 The two rami separated by a narrow cleft; the neuropodium more than 

 tudce as broad as the notopodimn, strictly lateral, consisting of an 

 extensive, sessile, sets-bearing area about 4 times as long transversely 

 as longitudinally, an obscure presetal lobe, and a postsetal lobe which 

 is provided at a short interval from the sets with a high fold bearing 

 about 12-14 conical marginal processes, the dorsahnost of which are 

 somewhat enlarged; notopodium generally similar, the setigerous area 

 raised as a very low compressed ridge, the postsetal lobe narrower 

 but higher, in correspondence with the longer setae, obhquely and 

 broadly palmate, somewhat like a moose's antlers, and bearing about 

 8 marginal processes wliich trend dorsally, toward which side they are 

 larger and the last sometimes bifid. Anteriorly the changes in the 

 paSipodia consist in a gradual reduction in size of the entire foot, 

 with a diminution of the neuropodial setigerous areas in vertical extent, 

 and a decrease in number of the postsetal processes, until the neuro- 

 podium bears but 3 or 4, and the notopodium visually a larger bifid one. 

 Posteriorly the neuropodial setigerous area suffers in extent by a reduc- 

 tion from the posterior and dorsal borders, the postsetal lobe gradually 

 30 



