REPORT ON THE CRINOIDEA. 125 



Colour in spirit, — brownish-white, or light yellowish-brown. 



Disk 7 mm.; spread about 18 cm. 



Localities. — Station 170a, July 14, 1874 ; near the Kermadec Islands ; lat. 29° 45' S., 

 long. 178° 11' W.; 630 fathoms; volcanic mud; bottom temperature, 39'5° F. Four 

 specimens and two fragments. 



Station 174 (b, c, or d), August 3, 1874 ; near Kandavu, Fiji; lat. (about) 19° 6' S., 

 long, (about) 178° 18' E.; 255, 610, or 210 fathoms '; coral mud; bottom temperature 

 (at 610 fathoms), 39° F. Two specimens. 



Remarks. — This species is readily distinguished from Antedon basicurva by the 

 smoothness of the arms and the appearance of the first radials externally (PI. XXI. fig. 1 ). 

 Another point of difference is that the wall-sidedness of the arm-bases extends out to the 

 fourth, or even to the fifth, brachial, which is not the case in any of the preceding 

 species. On the other hand the basal joints of the first pair of pinnules in the type form 

 (from Station 170a) are less flattened and not so distinctly trihedral as in Antedon basicurva 

 which occurs at the same station, so that the proximal pinnules are more like their 

 successors than is the case in that species. It is curious, however, that in the two 

 individuals from Station 174 (b, c, or d), where Antedon basicurva did not occur, the 

 lower joints of the first pinnule show a distinct tendency towards the trihedral form 

 characteristic of that type (PL XXII. fig. 4). 



The first radials are completely visible in all the specimens of Antedon incisa, though 

 they are shortest in those which are most mature (Pi. XXI. fig. 1), barely reaching half 

 the length of the second radials, to which they are nearly equal in some of the younger 

 individuals. A comparison of figs. 1 and 2 on PL II. will show other differences between 

 the calyx of this type and that of Antedon basicurva. The former has a relatively 

 smaller centro-dorsal, so that the radial pentagon covers it completely, and no part of it- 

 is exposed when the second radials are removed (PL II. figs, id, 2d). The under view 

 of the radial pentagon is much the same in the two types, except for the portion of the 

 first radial, which appears externally in Antedon incisa (PL II. fig. lc). But the lower 

 ends of the muscle-fossae in the latter species are almost entirely without the ridge and 

 furrow markings which are generally present in Antedon basicurva; the articular facet of 

 the cirrus-socket is relatively smaller in Antedon incisa than in Antedon basicurva, 

 and the radiating processes round the edge of the socket are less distinct (PL II. figs. 

 la, 2a). 



One of the six individuals obtained at Station 170a bore two large cysts of Myzostoma 

 tenuispinum, von Graff (PL XXI. fig. 1), a species which also infests Antedon basicurv<< 

 at the same station ; but there is no trace of cysts on either of the two examples of 

 Antedon incisa obtained at Station 174. 



1 The exact station, and consequently the exact depth, are not recorded. 



