T-OLYCH^ETA. — BENHAM. 157 



Ventrally the gland shields are darker than the neigh- 

 bouring parts ; the region between them and the chaetigerous 

 papillae on the abdomen being almost white. 



The gills are symmetrical, the ventral margin of the base 

 of each is inrolled in a plane sjjire which describes more 

 than a circle. The radioles (gill filaments) really arise in a 

 single series, as Quatrefages^ pointed out for iS'. indica, Sav., 

 but some have broader outer edges than others, and thrust 

 them out of series so that there appears to be an inner and 

 an outer rank. 



There are at least 130 radioles on each gill. The tip is 

 naked for a distance equal to about twice the length of the 

 upper pinnae. 2 



The dorsal tentacles are 15 mm. in length, the so-called 

 "palps" or buccal lobes are folded, directed forwards, and 

 about as long as the ventral lobe of the collar. 



The collar has a deep median cleft separating a right and 

 left ventral lobe, which is triangular with rounded tip, over- 

 arching the first segment. The lateral portion, which is 

 continuous with this, is low, shghtly reflected, and decreases 

 in height as it passes upwards to the level of the notopodia ; 

 here a deep incision separates it from a dorsal lobe, which is 

 directed forwards and inwards, at right angles to the former, 

 to meet, but not to unite with, its fellow in the mid-hne 

 anteriorly. 



The tube is a rich chestnut brown in colour, of tough horny 

 material ; the lower end is paler, transparent and flexible ; 

 the upper end opaque, much darker, and coated with fine 

 grey mud. The lower end being softer is crumpled and 

 twisted, so that the true length is difficult to determine, but 

 it is about 220 mm., with a diameter of 12 mm. at the upper 

 end. 



As to the capilliform chsetae of the thorax, the figures given 

 by Marenzeller exhibit some shght differences from my 

 observations, which, however, may be due to his artist. 

 Thus the flange on the shorter sort (PI. iii., fig. 4B) is some- 

 what narrower than in the chaetae examined by myself, and 

 the more slender sort (PI. iii., fig. 4A) is represented as having 

 a second flange, which is not always the case in the present 

 specimens ; while here the flange is broader than Marenzeller's 

 figure indicates. 



1. Quatrefages — Hist. Nat. Annel., ii., 18fi5, p. 432. 



2. I follow M'Intosh and Willey in the use of these terms, though it is 

 unfortunate that thev use " radiole "' in a different sense from Grube. 



