A MONOGRAPH OF THE EXISTING CRINOIDS 359 



In his memoir on the comatulids of the Challenger Expedition Carpenter described 

 Antedon acoela in detail and figured it on the basis of "several specimens" from station 

 214. In 1891 Dr. Clemens Hartlaub listed a specimen that had been presented by Car- 

 penter to the Gottingen Museum. 



Sir Arthur E. Shipley and Prof. E. W. MacBride republished one of Carpenter's 

 figures in 1901, Dr. Wilhelm Minckert discussed the syzygies in 1905, and Dr. Otto 

 Hamann in 1907 listed Antedon acoela and republished a figure of Carpenter's. 



In my first revision of the old genus Antedon published in 1907 Antedon acoela was 

 made the type of the new genus Poecilometra, and in my revision of the families Thalasso- 

 metridae and Himerometridae published in 1909 it was listed as Poecilometra acoela. 

 In my memoir on the crinoids of the Indian Ocean published in 1912 Poecilometra 

 acoela was listed and the synonymy and range were given. In 1913 I published notes 

 on six specimens from Challenger station 214 and compared this species with P. scalaris. 

 In my memoir on the unstalked crinoids of the Siboga Expedition published in 1918 1 

 recorded and gave notes on seven specimens from station 122 and on two from station 

 124. 



Prof. Torsten Gislen in 1924 discussed the peculiarities of the genital pinnules on 

 the basis of Carpenter's description and figures. 



POECILOMETRA SCALARIS (A. H. Clark) 



[See vol. 1, pt. 2, figs. 118, 132, p. 79, 229, p. 186, 288, p. 221, 539-542, p. 289, 849-855, p. 412.] 



Antedon scalaris A. H. CLARK, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 141 (description; Albatross 

 station 4918); vol. 34, 1908, pp. 437, 493. 



Poecilometra scalaris A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 362 (listed); Proc.Biol. 

 Soc. Washington, vol. 22, 1909, p. 18 (listed); Crinoids of the Indian Ocean, 1912, p. 225 (synon- 

 ymy; locality); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 50 (comparison with P. acoela); 

 Journ. Washington Acad. Sci., vol. 5, No. 6, 1915, p. 215 (southern Japanese species; range and 

 its significance); Unstalked crinoids of the Stto^a-Exped., 1918, p. 190 (in key; range). 



Poecilometra acoela A. H. CLARK, Proc. U. S. Nat. Mus., vol. 34, 1908, p. 265, fig. 1 (with an additional 

 IBr ossicle), p. 318 (southern Japan). 



Diagnostic features. The profiles of the IBr series and arm are smooth and con- 

 tinuous, those of the two sides making with each other an angle of about 60; the centro- 

 dorsal is of moderate size with a basal diameter of 4 mm.; the cirri are about XX, 20; 

 and the arms are 110 mm. long. 



Descrijjtion. The centrodorsal is short columnar terminating in a stellate figure 

 with rounded angles and an elevated center bearing about its edge numerous small 

 knoblike tubercles one at the base of each of the apical cirri. The cirrus sockets are 

 arranged in two irregular rows and a partial third, and roughly in two or three columns 

 in each radial area. 



The cirri are about XX, 15, about 20 mm. long, moderately stout. All the seg- 

 ments except the basal are longer than broad, the longest about twice as long as broad, 

 the distal only slightly shorter. There are no dorsal processes. The opposing spine 

 is minute, and the terminal claw, which is shorter, than the penultimate segment, is 

 stout at the base but tapers to a sharp point and is moderately curved. 



The radials are concealed. The IBr t are hemispherical with the curved side 

 proximal. The IBr 2 (axillaries) are rhombic with the lateral angles rather broadly 

 truncated, nearly twice as broad as long. The dorsal surface of the proximal and 



