A MONOGRAPH OF THE EXISTING CRINOIDS 55 



in consequence of this arrangement, 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 [IBri] oblong, fully twice as wide as long, in opposition and slightly flattened on proximal half 

 of lateral edges; costal axillaries (IBr 2 ] 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 prox- 

 imally, outer side somewhat longer than inner; second brachial similar, but relatively longer; third 

 and fourth brachials taken together [the first syzygial pair] 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 be- 

 tween the third and fourth, and between the sixth and seventh, or rarely seventh and eighth brachials, 

 and then at intervals of three oblique muscular articulations. First pinnule [Pi] 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, fur- 

 rowed on the inner face; second and third pinnules shorter, with only seven or eight joints, but 

 otherwise similar; succeeding pinnules somewhat longer, those at middle of arm with as many as 

 fifteen joints, of which the third, fourth and fifth are flattened and have conspicuously flaring mar- 

 gins; distal pinnules all somewhat broken. Sacculi more or less abundant, especially in distal 

 pinnules. Colour, in alcohol, cream-colour, sometimes uniform, but usually with more or less dis- 

 tinct markings of purple; very rarely the entire animal is dull purplish, lightest towards the tips of 

 the arms. 



Dr. Clark said that three dry specimens from Gabo Island in the collection of 

 the Australian Museum are somewhat smaller than the types, though otherwise simi- 

 lar. One is cream color, one is suffused with a reddish violet tint, and the third is 

 distinctly light reddish violet with indistinct small areas of cream color. 



Localities.- Thetis station 48 ; off Wollongong, 47 miles south-southwest of Sydney, 

 New South Wales, Australia; 100-102 meters; sand and mud to rock [H. L. Clark, 

 1909, 1916; A. H. Clark, 1911, 1912, 1915, 1916, 1918; Gisl6n, 1924] (15, M. C. Z., 377; 

 Australian Mus.). 



West-southwest of Gabo Island, Victoria; 128 meters; Capt K. Moller, December 

 1929 [H. L. Clark, 1938]. 



Eastern slope, Bass Strait; Endeavour [H. L. Clark, 1916] (2, M. C. Z., 724; 

 Australian Mus.). 



Geographical range. Coast of southeastern Australia from off Wollongong, New 

 South Wales, to Bass Strait, between Australia and Tasmania. 



Bathymetrical range. From 102 (?100) to 128 meters. 



History. This species was first described under the name Oligometra thetidis by 

 Dr. Hubert Lyman Clark from 15 specimens that had been dredged by H. M. C. S. 

 Thetis at station 48. Dr. Clark said that it is closely allied to adeonae Lamarck and 

 bidens Bell, but seems to be distinguished from both by the characteristic expansion 

 of the genital pinnules. It differs from adeonae further hi its smaller size, shorter 

 first pinnules, and fewer cirri with fewer segments; the latter also appear to be rougher 

 on the dorsal side. It differs from bidens, moreover, in the complete absence of the 

 tubercles on the elements of the IBr series and lower brachials, hi having a syzygy 

 hi the sixth or seventh brachial (though this is of little importance), and in somewhat 

 different lower pinnules. Dr. Clark noted that there is some uncertainty about the 

 pinnules of bidens as described by Bell; he says the first one has "some twelve joints" 



