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



the third brachial, the next between the eighth and twelfth, and others at intervals of 

 five to nine joints. 



The first pair of pinnules are relatively small and of tolerably equal size, consisting 

 of little over a dozen short joints. The second pair have longer joints, and those of the 

 sixth and following brachials have the third and the two or three next joints con- 

 siderably expanded so as to enclose the genital glands, which are protected by plates. 

 The fourth joint is larger than the rest, but not markedly so. 



Disk and arms distinctly but not extensively plated ; the pinnule-ambulacra have 

 fairly denned side plates with intervening sacculi, which are also abundant in the plating 

 over the genital glands. 



Colour in spirit,— white. 



Disk about 4 mm.; spread probably 12 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 species comes very near to Antedon tuberosa (PI. XXIII. fig. 2), but 

 is quite free from the numerous blunt spines which are so characteristic of that species, 

 its calyx and arms being almost completely smooth. Furthermore, the first pinnules are 

 relatively shorter and much less flagellate than in Antedon tuberosa, consisting of a 

 smaller number of joints and having an altogether stiffer appearance. 



17. Antedon fiexilis, n. sp. (PL XLIL). 



Specific formula — A.(2).^. 



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

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



Remarks. — This species will be described in the bidistichate group ; T but its ten-armed 

 variety finds a place here. It resembles Antedon tuberosa in the uniform expansion of 

 the lower joints in the genital pinnules ; but it differs altogether from that species in the 

 appearance of the first radials externally and in the absence of spines on the arm-bases, 

 while the cirri are stouter and have a larger number of joints than in either that type or 

 Antedon parvipinna. 



18. Antedon acideata, n. sp. (PI. XXIII. fig. 3). 



Specific formula — A.—. 



Description of an Individual.— Centro-dorsal subcorneal, bearing about fifteen cirri 

 in five irregular rows which are radial in position. The cirri have about eighteen joints, 



1 See p. 217. 



