POLYCH&TA FROM THE N.E. PACIFIC. 963 
Laffuie, 9, gives 27— -40). The segments differ from those of the 
median region chiefly in their shorter length. The whole region 
has the appearance of a string of beads, each segment being 
rounded and connected with its fellows only by a narrow neck, 
through which run the intestine and the nerve-cord (PI. ILI. fig. 6). 
The rounded appearance is due to the very much swollen portion 
of the segment which contains the generative organs. The two 
notopodia have coalesced for a considerable ‘part of their length, 
so that the free portions are very short indeed. In them are 
contained several (about 8) capillary setze. The neuropodia con- 
stitute a continuous narrow ridge half encircling the segment ; it 
bears on each side two uncinigerous tori, w hich are, however, by 
no means so well developed and independent as 1s the case in 
Chetopterus. The dorsal torus is a little smaller and placed 
rather more anteriorly. 
‘The small cirrus-like appendage (ci7.) found just outside the 
dorsal torus in Chetopterus is not present in Mesochwtopterus. 
MESOCHZTOPTERUS MINUTA, sp.n. (Plates IT, IIT. figs. 7, 8; 
Text-figs. 4, 5.) 
Occurrence.—This species was found twice by Mr. Cyril Cross- 
land during his visit to the Cape Verde Islands in August and 
September, 1904, once at St. Vincent, and again at Porto Praya. 
On the first occasion tufts of tubes were collected on the shore 
(?amongst sand) at low tide, and on the second tubes which 
contained much larger specimens were found projecting from and 
embedded in masses of nullipores. They were associated with 
Onuphis and a species of Spionid. In November 1913, I found 
this species also at Murray Island, Torres Straits, living in sandy 
tubes between tide-marks. Except for their generally smaller 
size, these Australian individuals conform with the description 
which follows in all essential particulars. 
The animal is milk-white in colour, with no pigmentation, 
except that of the gut shining through posteriorly. None of the 
individuals which reached me was quite complete, but those 
from Porto Praya were about 2°5 em. in length, while those from 
St. Vincent barely exceeded 15cm. In the largest the maximum 
breadth was very little more than 1 mm. 
The prostomium (Pl. Il. fig. 4) is a very distinct feature, better 
developed than in any species of Phyllochetopterus which I have 
been able to examine. It is conical in shape. The peristomiwm 
forms a deep cup like that in JZ. taylori, but not so complete 
owing to the size of the prostomium, and without the considerable 
development of pigment which occurs in the other species. At 
the base of the prostomium come off the two long peristomial 
tentacles. The eyes were only seen in the specimens from Porto 
Praya, in which, however, they were very distinct. They are 
curiously placed on the peristomium just outside the bases of the 
tentacles. 
In the anterior region the number of segments is variable. In 
6o* 
