A MONOGRAPH OF THE EXISTING CRINOIDS 359 



Oligomelrid.es adeonae), p. 34 (of P. H. Carpenter, 1888= Amphimetra pinniformis) ; Smithsonian 

 Misc. Coll., vol. 61, No. 15, 1913, p. 86 (of Bell, 1884 ^Oligometrides adeonae). 



Oligomelra pinniformis A. H. Clark, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 126 (listed); 

 vol. 22, 1909, p. 7 (listed), p. 42 (compared with O. studeri). 



Amphimetra sp. A. H. Clark, Die Fauna Siidwest-Australiens, vol. 3, Lief. 13, 1911, p. 466 (Holo- 

 thuria Bank, 15 fathoms; notes). 



Amphimetra pinniformis A. H. Clark, Notes Leyden Mus., vol. 33, 1911, p. 176 (identified as an 

 Amphimetra), p. 182 (compared with A. molleri; type redescribed) ; Crinoids of the Indian 

 Ocean, 1912, p. 34 (identity), p. 113 (synonymy; Andai; description of the type); Smithsonian 

 Misc. Coll., vol. 61, No. 15, 1913, p. 25 (Holothuria Bank, 15 fathoms; notes) ; Unstalked crinoids 

 of the Siboga-Exped., 1918, p. 83 (in key; range), p. 89 (references; localities from which known). 



Amphimetra planiformis Hawkins, Zool. Rec, vol. 48, 1911 (Oct. 1912), p. 43 (error). 



Diagnostic features. — A small species with the arms about 60 mm. long; the cirri, 

 which are curved throughout, have about 25 segments, which are two to three times 

 as broad as long; P 2 has 12 segments. 



Description. — The centrodorsal is a convex disk bearing marginal cirri. 



The cirri are about XII, 25. The segments are thick, and none of them are longer 

 than broad. Each one from the eighth onward bears a slight dorsal spine which be- 

 comes somewhat larger on the penultimate segment. 



The radials are partially visible. The IBrj are oblong and are almost completely 

 united laterally. The IBr 2 (auxiliaries) are widely pentagonal, nearly twice the length 

 of the IBri, with strong backward projections into the latter, the surfaces of both 

 ossicles rising somewhat toward their junction. 



There are 10 arms about 60 mm. long. The first brachials are bluntly wedge- 

 shaped and are closely united laterally. Each has its distal border incised to receive 

 a strong backward projection of the irregularly shaped second brachial. The first 

 syzygial pair (composed of brachials 3+4) is oblong. The next five brachials are 

 broad and nearly oblong with slight backward projections from their proximal edges 

 alternately on opposite sides of the arm. The following brachials are longer and 

 wedge-shaped, becoming more oblong again in the outer parts of the arms. 



Syzygies occur between brachials 3+4, and then very irregularly ; the second 

 syzygy may be anywhere from between brachials 15 + 16 to between brachials 22+23, 

 after which there is an interval of 6 to 19 muscular articulations between successive 

 syzygies. 



The stoutest pinnules are P 2 and P b ; these consist of about 12 thick segments, 

 which are slightly longer than broad. Pi and P a are less stout at the base but about 

 as long as P 3 and P , the immediate successors of which are the shortest pinnules on 

 the arm. The following pinnules gradually increase in length, their component seg- 

 ments becoming longer, but more slender. The outer pinnules are longer than the 

 lower ones, and being closely set give the arms a very feathery appearance. 



The disk is 5 mm. in diameter and naked. Sacculi are closely set along the 

 pinnule ambulacra. 



The color is white, the arms rather scantily clothed with a browner perisome so 

 that the ambulacra are close down on the muscles. 



Notes. — I examined this specimen in 1910 and in 1911 wrote that this is a small 

 species of the genus Amphimetra. The cirri are XII, 25; the dorsal spines on the outer 

 segments are sharp and long. The cirri are moderately stout, tapering slightly in the 

 distal half, with all the segments subequal, about twice as broad as long, those in 



