298 THE VOYAGE OF H.M.S. CHALLENGER. 



represented by Loven in his figure of the second radial also appears on an undoubted 

 syzygial face from further out on the ray ; and I have no doubt whatever that the 

 union of the two outer radials is really a syzygial one, though the usual radiating ridges 

 and furrows, which are so characteristic of syzygies in Comatulse, are not present on the 

 apposed faces. Traces of them are sometimes visible, however, as a series of little 

 elevations which radiate outwards from the central canal and produce the appear- 

 ance of a syzygial face with its ridges interrupted at intervals. But in other 

 cases the apposed faces are almost smooth, just as in the syzygies of Pentacrinus and 

 Rhizocrinus. The syzygies further out on the rays, however, are more normal in 

 character. 



There is a considerable amount of variation in the general features of this species. 

 The form which comes nearest to it is Actinometra novse-guinese ; but this is not known 

 to have more than four post-radial axillaries, while Actinometra typica may have 

 as many as seven. Furthermore the centro-dorsal of Midler's unique specimen of 

 Actinometra novse-gninese was described by him as having "15 Ranken und mehr" ; 

 though it shows traces of clefts at the sides and approximates therefore towards the 

 condition reached in Actinometra typica. Even in this last it ma} 7 bear a few rudi- 

 mentary cirri, as in the specimen figured by Loven ; 1 and there is a considerable amount 

 of variation in the extent to which it is sunk within the radial funnel. 



As in other species of Actinometra the tridistichate series is not unfrequently 

 replaced by a bidistichate one. This occurs on both sides of two rays in the Challenger 

 specimen (PL LV1I. fig. 1) ; and the Copenhagen Museum contains one anomalous 

 individual from Fiji in which eight out of the ten distichal series consist of but two 

 joints. I believe them to be articulated, and not united by syzygy, as one would 

 rather expect them to be. But then, it sometimes happens that there are three joints 

 in a palmar or post-palmar series, instead of the normal two ; and the first two of these 

 are syzygially united, a condition which is altogether anomalous for a three-jointed 

 series (see Rules 2, 6). On the other hand, however, it seems only natural that the 

 terminal faces of the two joints borne on any axillary should have the same character, 

 so that the normal syzygy of the one is accompanied by the abnormal syzygy of the 

 other. 



The range of this species, as at present known, extends from Malacca through the 

 Philippine Group, to Fiji, in all of which localities it belongs to the purely littoral 

 fauna. It was, however, obtained by the Challenger at a depth of over 200 fathoms, 

 viz. 210, 610, or 255 fathoms. I imagine for many reasons that it did not occur at the 

 greatest of these depths, no Actinometra having been yet obtained from below 600 

 fathoms. 



1 Ofversigt k. Vetensk. Alcad. Forhandl, 1866, No. 9, p. 230, fig. a. 



