THE RECENT CRINOIDS OP AUSTRALIA — CLARK. 781 



Family T H A L A S S M E T R I D ^, .1. IT. Clark. 



Gftnus P T I L O M E T R A, 4. iT. Clark. 



Ptilometra, 1907, A. H, Clark, Smiths. Miscell. Coll. (Quarterly 

 Issue), vol. 50, p. 358 (Comatula macronema, J. MiiUer, 

 1846). 



Diffsrential Characters. — The pinnules of Ptilometra are 

 strongly pismatic, stiffened, and all are approximately similar ; 

 Pi is smaller than the succeeding pinnules ; at the arm tip the 

 pinnules decrease in length very abruptly and the very short 

 crescentic brachials curve inward between the outermost pin- 

 nu'es, so that the arm tip at first sight always appears to be 

 broken off. The arms are stout and dorsally rounded basally, 

 becoming laterally flattened and strongly carinate distally, each 

 brachial with a long overlapping spine ; the division series are 

 always 2, and the lower part of the animal is compressed so that 

 the division series and arm bases are flattened against each other ; 

 the cirri are stout basally, but taper distally ; they are exceedingly 

 long, and may be longer than the arms though usually they are 

 about three-fourths of the arai length. The arms are from twelve 

 to thirty in number in fully grown individuals. The centrodorsal 

 is large and more or less columnar, and the cirrus sockets are 

 •closely crowded and more or less irregularly arranged. 



This genus is nearly related to Fteroinetra of the East Indies, 

 but in tliat genus the cirrus sockets are arranged in ten columns 

 on a more or less conical centrodorsal, and the proximal cirrus 

 segments bear long slender ventral overlapping spines. . 



Range. — Southern Australia, north to Dirk Hartog Island on 

 the west and Port Stephens on the east. 



PTILOMETRA MACRONEMA (/. Milller). 



Comatula macronema, 1846, J. Miiller, Monatsbei*. k. preuss. 

 Akad., 1846, p. 179 (King George Sound). 



"tAntedon ivilsoni, 1888, Bell, Ann. Mag. Nat. Hist. [6], vol. 2 

 pp. 402, 403 (Port Phillip).— 1890, P. H. Carpenter, Proc. 

 Roy. Soc. Vict. (N.S.), vol. 2, p. 135 {Port Phillip). 



Antedon macronema, 1889, Studer, Die Forschungsreise S.M.S. 

 "Gazelle," iii. Thiel, p. 185 {Dirk Hartog Island). 



Ptilometra dorcadis, 1909, A. H. Clark, Proc. Biol. Soc. Wash- 

 ington, vol. 22, p. 39 (Dirk Hartog Island, 7 fms.). 



Ptilometra macronema, 1907, A. H. Clark, Smiths. Miscell. Coll. 

 (Quarterly Issue), vol. 50, p. 358. 



