92 



Papers from the Department of Marine Biology. 



of such an association in this latter case. As we do not know whether 

 the original species is a commensal of crinoids, and in view of certain 

 morphological discrepancies, I describe the Torres Straits form as a 

 new variety. 



The two cotypes of P. minuta were incomplete individuals and on 

 this account the generic ascription was queried. In the series under 

 consideration there are three complete individuals, each having 15 pairs 

 of elytra. There is no reason why this species should not be definitely 

 assigned to the genus Polynoe, though there is good reason for under- 

 taking a revision of this and kindred genera. 



The characters which separate the Torres Straits form from the 

 original species are as follows: 



(1) The head is provided with two pairs of very distinct eyes, the one placed 

 laterally near the posterior angle, the other on the posterior border. The head 

 is covered with dark pigment, but there is a pigment-free ring round the pos- 

 terior eyes (the depression separating the two lobes of the head is free also). 

 In the Maldivian individuals there were no signs of eyes. 



(2) The lateral tentacles have a much swollen base in the type species 

 they are thin throughout. The lateral anterior angles are rounded instead of 

 slightly pointed. The palps are rather longer in proportion to the size of the 

 animal. 



There are a number of additional points, some of which could not be 

 mentioned in the original account, which are treated below: 



Colouration : The dorsum, with the exception of 2 longitudinal pigment-free 

 bands, is covered by dark brown pigment, not soluble in 70 per cent alcohol. 

 The markings are hidden by the elytra, which are uniformly pigmented. 



Shape: In smaller specimens tapering rather abruptly, in a larger one of 

 uniform breadth up to end. 



Number of elytra: Fifteen. They cover almost the entire dorsum. 



Setae of neuropodium: These fall into the following categories: (1) Very 

 long and slender, long drawn-out head slightly enlarged, ending in a blunt 

 apex with a projecting tooth of almost equal size underneath (type B). 

 (2) Thicker, head more pronounced, sharp incurved apex with prominent 

 tooth underneath; one or two of the dorsalmost often have prominent spines 

 on the convex surface of the head (C). Ventrally, however, spines are never 

 present (D) and they pass into (3) a still stouter type with shorter head, apex 

 still more incurved, tooth not so prominent (and in the ventralmost altogether 

 absent (E)). 



This succession of setae is almost identical with that in P. minuta, as I find 

 on comparison with the type specimens, which I did not describe with sufficient 

 fulness in 1910. Setae of type 1 occur there, though they were not mentioned 

 or described; the other types were given, and the only difference is the absence 

 of setae with a very definite row of spines in P. minuta. 



Measurements: Those of three complete individuals are given: 



