JOHNSON: POLYCHAETA OF PUGET SOUND REGION. 427 
coiling. Number of somites approximately 170 ; those of posterior 
portion of abdomen two-ringed. Thoracic somites, 43, of which 41 
are setigerous and 39 uncinigerous. 
Prostomium with dorsal crescentic groove separating a dorsal 
ridge from the ventral flap ; no eyes visible on surface. 
Peristomium with deep ventral groove, and dorsal semicircle of 
cirri. 
Branchiae two pairs, on third and fourth somites; moderate; 
anterior pair considerably the larger and more richly branched; 
main branches arising near the base; beyond the first ramification, 
the branching is dichotomous (Fig. 169). 
Setigerous lobes begin on fourth somite, increase slightly in size 
towards middle of thorax, then diminish ; the last few pairs very 
small. Setae of form usual in this genus (Fig. 170). 
Uncinigerous tori begin at fifth somite; first six pairs shorter 
than the rest; gradually increasing in length to the seventh where 
they attain the maximum length, and retain it to the 16th or 17th, at 
which point they gradually diminish, becoming flattened and almost 
indistinguishable on the abdomen. Uncini small, avicular, with five 
rows of teeth above the rostrum (Fig. 171 c ). They are uniserial 
on somites 5 to 10, and on 35 to end of series; biserial, on somites 
11 to 34. 
Length. 160 mm. ; greatest transverse diameter of thorax, 5 mm.; 
average of abdomen, 2 mm.; dorso-ventral diameter of thorax, 4.5 mm. 
A single individual of this species was collected by Miss Robert¬ 
son near Seattle. 
45. Lanice heterobranchia sp. nov. PI. 17, figs. 172-174. 
Thorax of 20 somites, 17 (?) setigerous. 
P rostomium of usual form ; no eyes. 
Branchiae three pairs, borne on somites 2-4; first pair (Fig. 172) 
much the largest and longest, with elongated main stem dendrit- 
ically branched ; ramifying branches very compact. Gills of second 
and third pairs short, without main stem. 
Setae (Fig. 173) with striated limb on each side; tip entire, from 
fourth (?) somite onward. Uncini from fifth somite, uniserial, alter¬ 
nating (“ rangee alterne,” Clapar^de), avicular, with three teeth in 
front of beak (Fig. 174). 
A single specimen in the Columbia University collection, too 
imperfect for complete description. The worm was enclosed in a 
mud' tube. The difference in the size of the branchiae of different 
pairs is the most striking character. 
