384 
THE VOYAGE OF H.M.S. CHALLENGEE. 
manner curves inward over the ovoid nerve-cords, leaving only the hypoderm and the 
cuticle external to the special area of the nerve-sheath. The fasciculi of the longi- 
tudinal dorsal and ventral muscles are similar to those in the common form. 
This form so closely approaches the British species that separation is difficult. Both 
Schmarda and Kinherg found it at the Cape. 
Cirratulus zebuensis, n. sp. 
Habitat. —Dredged at Station 209 (off Zebu, one of the Philippines), January 22, 
1875; lat. 10° 14' N., long. 123° 54' E.; depth, 95 fathoms; bottom temperature 71°'0, 
surface temperature 81°'0 ; sea-bottom, blue mud. 
A fragment of the anterior region, measuring about 25 mm. in length and 4 mm. in 
diameter. 
The head of this species is not much pointed, and though a little pigment occurs at 
the tip, there is no distinct evidence of eyes. The partial protrusion of the proboscis to 
some extent distorts the snout. The brancbise have the usual arrangement, and belong 
to the larger type of such organs. 
Unfortunately the fragment contains only the anterior bristles, no hooks being- 
developed in this region. The bristles are elongated and slender, without the distinct 
knife-blade-like flattening observed in the preceding species. The serrations on the 
maro;in are less marked than in the latter. 
It differs from many of its allies in the absence of hooks in the anterior region, even 
as far back as the fiftieth segment. 
The. fine greyish mud in the intestinal canal showed many Foraminifera, a few 
sponge-spicules, and one or two Diatoms. 
In transverse section the chief difference from Cirratulus cuTatus is the occurrence of 
more numerous fasciculi in both dorsal and ventral longitudinal muscles. While the 
cuticle also is well-marked, the hypoderm is somewhat thinner. The blood-vessels are 
distended with minutely corpusculated blood. 
Cirratulus assimilis, n. sp. (PI. XXIVa. figs. 11, 12). 
Habitat . — From the shore at Bermuda, adhering to the bristles of Eurytlioe. 
A fragment of the snout and anterior region of a small specimen, measuring about 5 
mm. in length, with a breadth of nearly 1 mm. 
This form approaches the British Cirratulus borealis, but is not identical therewith. So 
far as can be gathered from the mutilated example, it presents the following characteristics. 
