ECHINODERMATA— CLARK. 523 



one, beginning with the fourth, has, at middle of dorsal side, a 

 ■transverse ridge, which in side-view looks like a spine, that of the 

 temiinal joint being distinctly the largest, but even here not 

 nearly equalling thickness of joint ; on basal joints dorsal ridge 

 somewhat serrulate, while distal margin of joint projects as a 

 more or less evident second ridge ; in consequence of this arrange- 

 ment, the dorsal side of some joints, notably fifth-eighth, appears 

 as though provided with two low spines, one nearly at middle and 

 one distal ; terminal claw, usually sharp, curved and scarcely as 

 long as penultimate joint. Radials plainly visible, but short; 

 first costals oblong, fully twice as wide as long, in apposition and 

 slightly flattened on proximal half of lateral edges; costal 

 .axillaries pentagonal, much wider than long. Ten arms, rather 

 more than 25 mm. long; first brachials nearly oblong, much wider 

 than long, more or less in contact proximally, outer side some- 

 what longer than inner ; second brachial similar, but relatively 

 longer ; third and fourth brachials taken together as long as wide, 

 squarish ; fifth and sixth decidedly wider than long ; the following 

 nine or ten more or less wedge-shaped, but succeeding ones rather 

 irregular ; on distal part of arm the most distal portion of the 

 ■ distal edge of each brachial tends to project, though not sufficiently 

 to be called a spine or even a tubercle. Syzygia occur between 

 the third and fourth, and between the sixth and seventh, or 

 I'arely seventh and eighth brachials, and then at intervals of three 

 • oblique muscular articulations. First pinnule (PL xlvii., fig. 1) 

 nearly 6 mm. long, with ten-twelve joints, the first about as long as 

 wide, second a little longer, third twice as long as wide, fourth and 

 fifth about the same, the succeeding gradually decreasing in length, 

 so that the minute terminal joint is scarcely longer than thick ; 

 all the joints are semi-cylindrical, smooth, furrowed on the inner 

 face ; second and third pinnules shorter, with only seven or eight 

 joints, but otherwise similar ; succeeding pinnules somewhat lon- 

 ger, those at middle of arm (PI. xlvii., fig. 2) with as many as fifteen 

 joints, of which the third, fourth and fifth are flattened and 

 have conspicuously flaring margins; distal pinnules all somewhat 

 broken. Saeculi more or less abundant, especially in distal 

 pinnules. Colour, in alcohol, cream-colour, sometimes uniform, 

 but usually with more or less distinct markings of purple; very 

 rarely tiie entire animal is dull purplish, lightest towards the tips 

 of the arms. 



Fifteen specimens from Station 48. Off" WoUongong, 55-56 

 fathoms; sand and mud to rock. 



This species is closely allied to adeonce, Lamk., and bidens, Bell, 

 but seems to be distinguished from either by the characteristic 

 •expansion of the genital pinnules. It differs from adeonce. further, 

 in its smaller size, shorter first pinnules, and fewer cirri with 



