Benhasi. — Some Xew Zealand Polychaetes. 163 



Fam. Chlorhaemidae. 



Flabelligera bicolor Schmarda. 



Pherusa bicolor Schmarda, Neue Wirbellose Thiere, 1861, p. 21, 

 pi. xx, fig. 169. Flabelligera lingulata Ehlers, Neuseelandische 

 Annelideu, 1904, p. 47. F. semiannulata Ehlers, loc. cit., p. 150. 



I received nine specimens of this species, and am able to add one or 

 two notes to the account of Ehlers. 



The two more carefully examined are 30 mm. and 50 mm. in length, 

 with 55 and 58 segments respectively. 



The body-wall is pale brown in the preserved state (in formalin), which 

 is distinctly segmented in those specimens which are not distended with 

 food. When this, however, is the case the anterior five or six segments 

 show the segmentation as a prominent ridge at the anterior margin. Then 

 the body commences to enlarge, and from the 8th to 16th the wall, hitherto 

 thick and opaque, is thin and transparent, owing to the great amount of 

 distension allowing the contained viscera to be seen and the muscular 

 fibrillae to be distinguished in the wall itself. From this point the body 

 gradually decreases in diameter towards the anal segment. In such a 

 specimen, which resembles that described by Ehlers under F. lingulata, 

 the dimensions of a specimen of 50 mm. in length are : the peristomium is 

 1*5 mm. wide ; the 7th segment about 2-5 mm. ; and the greatest breadth 

 is 6 mm., at about the 10th or 12th segment. At the 18th it is 3 mm., 

 and at about four segments from the end 1 mm. wide. It is thus spindle- 

 shaped. 



But in those cases in which the gut is not distended the differences are 

 much less ; in a 30 mm. individual its width over the greater part is 2 mm., 

 rather less at the peristomium and towards the hinder end. 



In the distended state, also, the colour differs, for it loses its brown 

 tint, and becomes, owing to the stretching of the wall, very dark bluish 

 or black in the anterior half, excluding the first 4-5 segments, and, as 

 the gut is loaded with sand, this may be mottled. 



In one case in which this distension had attained probably its maximum 

 the segmentation of the body-wall was still indicated by white transverse 

 lines on the dorsal surface in the middle region, while at the anterior and 

 extreme posterior ends the ventral ridges at the anterior end of the segments 

 persist. 



The body-wall is enclosed in a jelly of considerable thickness, which, 

 however, diminishes when the specimen is placed in alcohol and left for a 

 time. But the amount of jelly seems to vary in different individuals ; 

 in one specimen from Denham Bay the notopodial chaetae do not, or only 

 just, project beyond it. It is traversed by very numerous thread-like papillae, 

 which terminate in a swollen apex. These spring from the entire surface 

 of the body-wall, and are especially abundant and long around the noto- 

 podial chaetae. 



The dorsal surface of the body is rounded, the ventral flat. 



The head is concealed by a nearly complete circle of long capillary 

 chaetae, which constitute the cephalic crown, which is itself hidden by the 

 jelly and papillae. 



The chaetae project for a distance of 5 mm., equal to the length of the 

 peristomium and five or six following segments. These chaetae, which agree 

 in structure with the notopodials, are rooted in a narrow, upstanding, nearly 

 vertical fold of the anterior wall of the peristomium, which forms a con- 



6* 



