rOLYCH^TA. — BENHAJI. 159 



secondary position, and it is this feature of the present species 

 which led to its being placed in the genus Pomatostegus, for 

 the discs are in two or more tiers and there are no outgrowths 

 from the surface of the opercular disc such as occur usually 

 in Spirobranchus, but, on the other hand, it is calcareous 

 instead of being of horny material. 



There are one or two features in which the jaresent worm 

 appears to differ from that described by Marenzeller — (a) in 

 the extent of the basal denticulated area on the collar 

 chsetae, and (6) in the presence of a distinct lateral notch 

 in the collar. 



A comparison of the worm with that briefly described by 

 M'Intosh under the title '' I Pomatoceros strigiceps " from 

 New Zealand seas leads me to identify that worm withMaren- 

 zeller's. It is certainly not Pomatoceros strigiceps, JNIorch, 

 which is very common along our shores, and has been 

 identified by Ehlers as P. coeruleus, Schmarda.^ 



The fcAV details given by jM'Intosh and his figures of the 

 chsetse agree with the present species. The figure of the side 

 view (PL Iv., fig. 4), though rather obscure in details, in that 

 the outline of the collar lobes are not definitely shown, when 

 read in association with his account of it, renders it very 

 evident that the " peculiar region having the aspect of a 

 partially closed fan," Ij'ing in front of the dorsal lobe of the 

 collar, corresponds with \Ahat I term the " latero-dorsal 

 lobe " in my account below. 



It seems desirable to add a short account of the worm with 

 some figures to supplement Marenzeller's. 



The dimensions agree almost precisely with those given 

 by him (PL xlviii., fig. 46). The operculum carries 3, 4 or 5 

 discs, which are circular, pale pinkish in colour, calcareous, with 

 a smooth upper face, which is nearly flat or slightly concave ; 

 there are neither outgrowths nor raised radial ridges on the 

 surface. The vertical surface between the successive discs 

 is feebly ridged longitudinally. In one specimen, possessing 

 five discs, the terminal one is produced to form a smooth 

 cone (PL xhaii., fig. 49). (Has this been worn away in other 

 specimens ? Does this correspond to the characteristic spines 

 of Spirobranchus ? It is A^orth noting that in some species 

 such as »S'. maldivensis, Pixell,- the disc is unarmed and flat.) 



1. Ehlers— Neuseeland. Annelid., 1904, p. 67, and 1907, p. 30. 



2. Pixell— Loc. cit, p. 84. 



