REPORT ON THE CRINOIDEA. 221 



syzygy in the third brachial ; the next not till after the twentieth, and others at long 

 intervals (nine to twenty-five joints). 



The second brachial bears a stout pinnule about 12 mm. long and composed of some 

 twenty joints, the lowest of which are much larger than their successors and of almost 

 prismatic shape, being flattened against the corresponding joints of the adjacent 

 pinnules. The third brachial has a similar but slightly smaller pinnule, and its 

 successors are of about the same length, but have broader and flatter joints. The later 

 pinnules gradually become elongated, but none of their lower joints are conspicuously 

 wider than the rest. In the styliform middle and outer pinnules the first joint is 

 flattened and expanded, with a curved distal edge. 



Disk thickly plated, and also the arms, both along the ambulacra and in the inter- 

 articular regions. The genital pinnules are protected by irregular plates, and the 

 ambulacra of the later pinnules have well-defined side plates, with alternating sacculi, 

 which are also fairly abundant on the genital pinnules. 



Colour in spirit, — the perisome dark blackish-brown, but the skeleton whiter. 



Disk 12 mm.; spread nearly 50 cm. 



Locality.— Station 192, September 26, 1874; near the Ki Islands; lat. 5° 49' 15" S., 

 long. 132° 14' 15" E.; 140 fathoms; blue mud. One specimen. 



Remarks. — This type is a larger and more massive species than Antedon flexilis or 

 Antedon patula, which resemble it in the characters of the stout cirri, the flattened 

 lower pinnules, and the thickly-plated ventral perisome. But the centro-dorsal is 

 altogether different and the calyx less tubercular than in these two species. The centro- 

 dorsal is a thick disk, with the cirri closely set round its margin in two or three tiers. 

 (PI. XLIV. fig. 1), while the wide dorsal surface, which is slightly concave, is entirely 

 free from them. The radial axillaries are relatively wider and much less prominent than 

 in Antedon patida (PI. XLIIL), and the first radials are not so entirely concealed as in 

 that type (PI. XLIV. fig. 1). In this respect, as also in the smoothness of the arms, 

 Antedon robusta approaches Antedon flexilis (PI. XLII.) ; but the lower joints of the 

 genital pinnules are not so markedly expanded as in that species. 



The single specimen of Antedon robusta which was obtained by the Challenger has 

 two distichal axillaries, but it is quite possible that other examples may some time be 

 discovered which have only ten arms, as is the case in Antedon flexilis, two specimens 

 of which have three axillaries each, while the other two are only ten-armed. In that 

 case Antedon robusta would find a place in the Basicurva-gvoup by the side of Antedon 

 flexilis. 



