REPORT ON THE CR1NOIDEA. 243 



Locality. — Station 214, February 10, 1875 ; off the Meangis Islands; lat. 4° 33' N., 

 long. 127° 6' E.; 500 fathoms; blue mud; bottom temperature, 41° - 8 F. Several 

 specimens, some with cysts of Myzostoma tenuispinum. 



Remarks. — This species is readily distinguished from all the other tridistichatc forms 

 of Antedon, with the exception of Antedon inasqualis (PI. LI. fig. 2), with which it has 

 many characters in common. It does not reach the size of that species, however, and 

 differs in various respects from its younger stages, as will be explained further on. 



The cirri have rather elongated joints, which are unusually smooth, hardly any trace 

 of an opposing spine appearing on the penultimate. The centro-dorsal is much flattened 

 at the dorsal pole and has more or less distinct indications of interradial ridges on its 

 sides, which are produced upwards into rather prominent processes at the angles (PI. II. 

 fig. 4a). It is considerably wider than the radial pentagon (PL II. fig. Ad), so that the 

 first radials are entirely concealed by it, with portions of the second as well. Both 

 edges of these latter joints are thus strongly curved in the adult calyx, the proximal 

 edges occupying the hollows between the interradial processes of the centro-dorsal, 

 while the distal edges are incised to receive the strong backward processes of the 

 axillaries (PL L. fig. 1). The first two distichals, or in their absence the first two 

 brachials, have a similarly tubercular junction. 



Antedon angusticahjx is a species of considerable interest from its presenting several 

 of the characters which are distinctive of three species of Antedon that were found 

 associated in the South Pacific, near the Kermadec and the Fiji Islands respectively 

 (Stations 170a and 174). Two of these, with only ten arms {Antedon basicurva and 

 Antedon incisa), are characterised by having less than thirty smooth cirrus-joints, and 

 some of the lower joints of the genital pinnules expanded on the outer side so as to 

 form a protection for the genital glands, which are also covered by a strong anambulacral 

 plating (PL XXI. figs. 2a, 2b). Antedon insequalis (PL LI. fig. 2), which also occurred 

 at both Stations (Nos. 170a, 174), is a tridistichate species possessing these same 

 peculiarities ; while Antedon angusticalyx, which closely resembles it in the characters 

 of the arm-divisions and genital pinnules (PL L. figs. 1, 2), represents the tridistichate 

 type in the North Pacific. But the sides of its rays are less distinctly flattened than in 

 the three species from the South Pacific ; while those of the ten-armed species (Antedon 

 acosla), which is associated with it, have no flattening at all (PL XVI. fig. 1), though 

 the cirri and genital pinnules have much resemblance to the corresponding parts of 

 Antedon basicurva and Antedon incisa. 



Some of the characters of Antedon angusticahjx and Antedon iniequalis appear in 

 Antedon granulifera of the Caribbean Sea. But this type usually has two post-radial 

 axillaries, i.e., distichals and palmars, and the rays are less closely in contact than is the 

 case in the Pacific species. 



