A MONOGRAPH OF THE EXISTING CRINOIDS 377 



by Svend Gad); Mem. Australian Mus., vol. 4, 1911, p. 766 (synonym of discoidea); Crinoids 

 of the Indian Ocean, 1912, p. 112 (same).— Reichensperger, Abh. Senck. naturf. Ges., vol. 35, 

 Heft 1, 1913, p. 94 (characters discussed). 



Antedon milberli var. dibrachiata A. H. Clark, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 2 (specimen 

 so labeled in the Paris Mus. possibly the original of GuiSrin-Meneville's figure). 



Comatula {Antedon) milberti var. dibrachiata A. H. Clark, Bull. Mus. Hist. Nat., Paris., 1911, p. 251 

 (MS. name by P. H. Carpenter found with a specimen of A. discoidea from Australia) ; Mem. 

 Australian Mus., vol. 4, 1911, p. 767 (comparison with type of discoidea; appears to be the origi- 

 nal of Gu6rin-M<jneville's figure). 



Actinometra brachiolata (B. M., MS.) A. H. Clark, Smithsonian Misc. Coll., vol. 61, No. 15, 1913, 

 p. 75 (name found with a specimen of this species in the B. M.). 



Diagnostic features. — A medium-sized or rather large form with the cirri mod- 

 erately stout and straight proximally, becoming more slender and curved distally; 

 the cirri have 34-51 segments of which the longest are about as long as broad and the 

 distal bear short dorsal spines or pointed tubercles; the arms are 110-200 mm. long; 

 prominent sharp-pointed synarthrial tubercles are present. 



Description. — The centrodorsal is large, hemispherical or somewhat columnar, 

 with a large convex polar area. The cirrus sockets are arranged in two crowded 

 alternating marginal rows. 



The cirri are XVII, 37-45 (usually about 40), 30 mm. long, decreasing very 

 gradually in thickness for the first 8 or 10 segments, then remaining uniform. The 

 first segment is short, about twice as broad as long or rather shorter, and those follow- 

 ing gradually increase in length, becoming about as long as broad after the twelfth or 

 sixteenth, and about one- third broader than long in the terminal portion of the cirri. 

 From about the eighteenth segment onward prominent, though small, dorsal spines 

 are developed, which are subterminal in position, becoming terminal on the last two 

 or three segments. The opposing spine is small, median in position, not rising to 

 more than one-third the width of the penultimate segment in height. The terminal 

 claw is somewhat longer than the penultimate segment and is moderately curved. 



The radials project slightly beyond the rim of the centrodorsal; their dorsal 

 surface is parallel to the dorsoventral axis of the animal. The IBri are short, oblong, 

 about three times as broad as long. The IBr 2 (axillaries) are rhombic, about twice 

 as broad as long, proximally rising to a low conical tubercle with the IBrj. 



The 10 arms are about 130 mm. in length. The first brachials are wedge-shaped, 

 about two and one-half times as broad as the exterior length, almost entirely united 

 interiorly. The second brachials are irregularly quadrate, rather larger than the first. 

 The first syzygial pair (composed of brachials 3+4) is obloDg, two and one-half times 

 as broad as long. The following brachials to the tenth are slightly wedge-shaped, 

 about three times as broad as long, and those succeeding become more obliquely 

 wedge-shaped, somewhat over twice as broad as their greatest length, then gradually 

 shorter and less and less obliquely wedge-shaped, and very short and discoidal after 

 about the proximal third of the arm. 



Pi is small and comparatively slender, 7 mm. long, with 15 segments, all of which 

 are somewhat longer than broad, the first two and the terminal three or four being 

 not quite so long as the others. P 2 is 11 mm. long, stouter than Pi, with 17 segments, 

 of which the first two are about as long as broad and the remainder are slightly longer 



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