12 Journal of Entomology and Zoology 
higher; entire second somite very short, not more than one-fourth as long as I. Nuchal 
cirri short and conical, much shorter than the peristomium, transversely wrinkled or 
sometimes distinctly annulated. Notocirri slenderly conical, becoming more slender 
in posterior region as usual; with some weak encircling wrinkles but not distinctly 
divided into articles. Branchiae begin as single filaments on IX or sometimes on VIII. 
Branchiae of X each consisting of two filaments. The number in several of the suc- 
ceeding branchiae increases to three, then again falling to two, and, finally, the last 
eight pairs or so are again simple filaments. The last branchiae in the type occur on 
XXXII. Anal cirri short, slenderly conical. Moxillae strongly chitinized; brown, 
with edges in part black. In maxillae II the right plate has six large teeth, the outer 
left plate four and the odd or inner left plate seven or eight. III with nine teeth or 
crenulatious. Number of segments in type one hundred and nine. 
Length, 43 mm.; greatest width, exclusive of parapodia, 2.6 mm. An incomplete 
larger specimen has a width of 3.2 mm. 
Type—M. C. Z. 2, 154. 
Taken among holdfasts of kelp. (C. F. Baker, June 30, 1911.) 
Arabella lagunae sp. nov. 
As compared with 4. attenuata Treadwell, this is a smaller species differing in 
appearance in being brown of a decided greenish tinge, excepting on the prostomium 
and at the caudal end. The prostomium is less narrowed cephalad, being more 
broadly rounded across anterior end. Median eyes not exceeding the lateral in size. 
Maxillae V represented by simple small hooks. IV with five teeth of which the most 
ectal (upper) is long and slender, the two next much shorter and finer and the two 
innermost closer together. III with fine teeth similarly arranged and formed. Maxillae 
II nearly symmetrical; the left one with seven teeth of which the most anterior one is 
much largest, the right with an additional small tooth in front of (ectad of) the 
large one; neither of the plates extending caudad of the anterior end of the dental 
series of I. I with seven or eight well developed teeth; the carriers very long and 
slender, black throughout. In the paraphodia the posterior lobe is well developed, 
stout and conical, distally somewhat blunt or rounded, extended ectad or caudo-ectad 
and is always shorter than the setae. Setae all simple, limbate, in a single series of 
mostly six in the middle region of the body. Setae with the usual double or sigmoidal 
curve over the limbate part, the first bend or geniculation unusually strong, angular; 
tip becoming fine and hair-like. Body tapering caudad, pointed at the posterior end, 
ending in two blunt lobes. Number of segments in the type one hundred and ninety-one. 
Length, 46 mm.; width, exclusive of parapodia, 2 mm. 
Type—M. C. Z. 2, 155. 
Taken at the shore “under rocks.” 
Arabella mimetica sp. nov. 
Resembling the preceding species though smaller and more slender. Superficially 
differing obviously in the form of the prostomium which is much more narrowed distad 
and is neither depressed nor furrowed either dorsally or ventrally. Eyes smaller, 
cbscure. Maxillae resembling those of the other species in general, but differing 
strongly in the second pair in which the right plate, instead of being symmetrical with 
the left one, is decidedly long and extends far proximad along the dental line of I 
and bears about fifteen teeth as against only six on the left one and eight on the cor- 
