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



Ten arms of smooth, obliquely quadrate joints. Syzygies on the third, eighth, and 

 twelfth brachials, and then on every alternate joint. 



The first pair of pinnules are about 7 mm. long and consist of some eighteen elongated 

 and rather dice-box-shaped joints. The second pair but little smaller, and the following 

 ones all long, decreasing but slowly in size, and retaining the elongated joints, which 

 bear short and fusiform genital glands. The later pinnules are slender again, but not as 

 long as the first pair. 



Disk and ambulacra naked ; sacculi moderately abundant. 



Colour in spirit,- — dirty white. 



Disk 4 mm.; spread probably about 4 cm. 



Locality.— Station 320, February 14, 1876; lat. 37° 17' S., long. 53° 52' W.; 600 

 fathoms ; green sand ; bottom temperature, 37°'2 F. Three mutilated individuals. 



Remarks. — The length of the cirrus-joints and the very regular alternation of the 

 syzygies beyond the twelfth brachial readily distinguish this species from Antedon remota. 

 It is strikingly characterised by the great length of the joints composing the lower 

 pinnules, as is well seen in the immature specimen shown in PI. XXX. fig. 1. Its genital 

 glands are but little developed ; but a somewhat older individual has tolerably large 

 testes, and in that represented on PL XXX. fig. 2, there are much swollen ovarian sacs, 

 extending over about three pinnule-joints, with thin walls through which large white ova 

 are visible. 



11. Antedon tenuicirra, n. sp. (PI. XXX. figs. 4-8 ; PI. XXXIII. figs. 4, 5). 



Specific formula — A.y. 



Centro-dorsal hemispherical, bearing thirty or more long and slender cirri of fifteen 

 to twenty-five joints or more, the first three of which are very short and the rest much 

 elongated. 



First radials just visible ; the second short, rounded and oblong, free laterally and 

 scarcely incised by the axillaries, which are widely rhombic, with open proximal angles. 

 Ten arms, of smooth obliquely quadrate joints. Syzygies in the third and eighth 

 brachials and then at intervals of two to five joints. 



The first pair of pinnules are long, slender, and delicate, composed of numerous joints 

 which are but little longer than wide. The second pair is of about the same length, but 

 consists like its successors of stouter and more elongated joints, which become slender 

 again in the distal pinnules. 



Disk and ambulacra naked ; sacculi moderately abundant. 

 Colour in spirit, — light brown. 

 Spread, 11 cm. 



