COMATULJD OF THE MERGUT ARCHIPELAGO. 



813 



Colour in spirit, dark blackish brown. 



Disk 30 millim. ; spread 25 centim. 



Habitat. King Island ; sublittoral. Three specimens. 



Remarks. This fine species exhibits the same peculiarities of the 

 rays and their subdivisions as are characteristic of Actinometra 

 paucicirra ; but whereas the presence of palmar series is an ex- 

 ception in A. paucicirra, so that the number of arms is limited to 

 twenty, palmars are always present in A. notata. Furthermore, 

 they may be followed by one or even by two post-palmar series 

 (PI. XXVI. fig. 7), and the number of arms therefore is sometimes 

 twice as great as in Actinometra paucicirra. In the latter species, 

 too, which normally has but four arms to the ray, the two outer 

 arms generally have a syzygy in the third brachial ; but in A. 

 notata, with six to twelve arms on the ray, this character occurs 

 but rarely (PI. XXVI. fig. 6). The latter species is further 

 distinguished from A. paucicirra, which has no cirri in the adult 

 condition, by the large size of the centro-dorsal, and its numerous 

 and well-developed cirri (PI. XXVI. figs. 11, 12). It would seem, 

 however, that the centro-dorsal of A. notata undergoes a certain 

 amount of retromorphosis before reaching maturity ; for it is 

 relatively largest in the youngest individual (PI. XXVI. fig. 8), 

 partly concealing the second radials, which are united laterally, 

 and its dorsal surface, though flat, is not hollowed in any way. 

 In the two adult individuals, however, portions of the first radials 

 are visible, in one case a considerable amount (PI. XXVI. fig. 7), 

 while the dorsal surface of the centro-dorsal is distinctly hollowed. 



The disk of the youngest individual is entirely naked ; while 

 those of the two larger forms bear well marked calcareous granules 

 in the anal interradius. The arrangement of the ambulacra in 

 one of them is very singular (PI. XXVI. fig. 6). The mouth seems 

 to be radial, and the number of groove-trunks connected with the 

 peristome is very considerable. The aboral portion of the left an- 

 terolateral ray B 2 , which includes the arms borne upon its pos- 

 terior distichal axillary, has an altogether abnormal groove-supply. 

 The ambulacra of its anterior arms (6 3 ) are directly connected 

 with the peristome, as is often the case ; one would therefore 

 expect to find those of its posterior arms, 5 4 , supplied by a branch 

 of the single primary ambulacrum, which in the ordinary species 

 of Actinometra passes round the disk to reach the left postero- 

 lateral ray (see woodcut). In the specimen before me, however, the 

 ambulacrum proceeding in this direction from the left posterior 



27* 



