18 B Canadian Arctic Expedition, 1913-18 
present species is a less slender form than the genotype and consists of a much 
smaller number of somites,—seventy-five as against two hundred and six. 
The branchie in benhami become much longer, at their maximum equalling 
the width of the segments; they continue to the eighty-sixth segment, instead 
of terminating near the twenty-ninth or earlier. In arctius the fine, elongate 
capillary sete of the superior group of notopodia, and in part, at least, of neuro- 
podia, seem to form a characteristic feature. 
Anaspio, n. gen. 
__ Prostomium without cornua, rounded anteriorly and prolonged caudad; 
without nuchal cirrus. In genotype one pair of eyes. Branchiew in genotype 
two pairs, on third and fourth somites, wholly free from the parapodial lamella. 
Parapodia all free from each other, none of the neuropodia being connected 
by a membrane; no interparapodial pouches. Anterior parapodia bearing only 
capillary sete. Hooded crochets appearing in neuropodia caudad but notopodia 
remaining with only capillary sete. Crochets with beak bifid and lacking 
apical tooth. 
Genotype. A. boreus, n. sp. 
Close to Spionidés but wholly lacking the characteristic lateral pouches 
of the latter and the nuchal cirrus. The crochets seem to be of distinctive 
form. 
Anaspio boreus, n. sp. 
Type specimen.—Cat. No. 88, Victoria Memorial Museum, Ottawa. 
One specimen. 
The type is incomplete caudally, at present embracing the head and thirty- 
six setigerous somites. It is only 12 mm. long. Body depressed, moderately 
convex above, more flattened beneath, covered in part anteriorly by the foliaceous 
developments of the parapodia. 
The prostomium is elongate, narrowly subtriangular with base cephalad. 
Anterior end weakly convex. Posteriorly it is prolonged to or nearly to the 
third setigerous segment in a thick palpoidal process fused with the dorsum 
throughout. Just in front of the beginning of this posterior region is one pair 
of eyes; these are small and wide apart. Vague pigment specks may represent 
a second pair of eyes farther forward and farther apart. (Pl. IV, fig. 2). 
The peristomium forms the lower lip and the usual lateral cephalic lobes, 
the latter broadly rounded posteriorly and narrowing cephalad. Tentacular 
cirri lost. (Pl. IV, fig. 2). 
The parapodia are prominent and conspicuous, particularly anteriorly. 
They are broadly attached, with two lobes almost continuous. Presetal lobes 
low, but the postsetal lamelle large and foliaceous. The postsetal lamella of 
notopodia I of moderate size, rising above in a triangular tip. The corresponding 
lamelle of the second, third, and fourth parapodia are much longer, being longer 
all along the setigerous. line with the dorsomesal ends much more prolonged; 
those of the third parapodia largest, overlapping above the dorsum. The 
notopodial lamellz of the fifth and sixth parapodia are abrunptly smaller and 
more widely separated, though still large and pointed above. The fol- 
lowing ones rapidly lose their dorsal prolongations, becoming lower and evenly 
rounded, their dorsomesal edges in the first few extended mesad and conspicu- 
ously connected across dorsum in a low ridge or integumental fold, this fold 
becoming less marked posteriorly. Posteriorly the postsetal lamelle both of 
notopodia and of neuropodia become low and inconspicuous. The postsetal 
lamelle of the anterior neuropodia vertically much shorter than those of the 
notopodia, but high, decreasing in size in correspondence with the reduction of 
the dorsal lamella. 
There are only two pairs of branchie, these occurring on the third and 
fourth setigerous segments. They are thick, subconical processes free from 
