145 

 2. Pterometra pulchcrrima (A. H. Clark). 



A. H. Clark. Proc. U. S. National Museum, vol. 36, 1909, p. 400 [Ptilometra pulcherrima). 



Proc. U.S. National Museum, vol. 39, 191 1, p. 547 {Aster ometra pulcherrima). 



Crinoids of the Indian Ocean, 19 12, p. 193 [Asterometra pulchcrrima). 



Stat. 144. Anchorage north of Salomakiëe (Damar) Island. 45 Metres. 1 Ex. 



This specimen agrees vvell with the type. There are twenty arms 90 mm. to 95 mm. 

 long. The cirri are XX, 92 — 96, yS mm. long. The colour in alcohol is white. 



2 nJ Subfamily Thalassometrinae A. H. Clark. 

 Key to the Genera of the Subfamily Thalassometrinae. 



a 1 Ten arms 



b 1 genital pinnules with the third-fifth segments greatly expanded, forming 

 a broad roof over the gonads ; calyx and arm bases smooth ; 30 — 40 

 cirrus segments (Straits of Florida and southeastward to 



Grenada) Horaeometra 



b 3 no expansion of the segments of the genital pinnules 



c 1 ossicles of the division series and of the arm bases with numerous 

 prominent spines which may be more or less confined to the borders 

 of the ossicles and to the median line, or generally distributed over 

 the dorsal surface ; ossicles of the division series and first two brachials 

 sometimes with a slight carinate process bearing spines along the 

 crest; arms beyond the second brachial well rounded dorsally, never 

 carinate ; Pj very stout, much stouter than the succeeding pinnules, 

 though with a delicate tip; 10 — 13 (usually 10) arms; division series 

 usually 2, sometimes 4(3 + 4) (Morocco and Madeira south- 

 ward to Ascension and the Crozet Islands; east Africa 

 to the Kermadec, Galapagos, Hawaiian and western 



Aleutian Islands, and southern Japan). ., Thalassometra 



c 2 ossicles of the division series and of the arm bases smooth, without 

 spines on the dorsal surface, though they may have irregular processes 

 on their lateral borders, and isolated spines on their proximal and 

 distal borders; P p though larger and stouter than those succeeding, 

 is not especially enlarged 

 d 1 cirri long, with more than 40 segments 



e 1 division series and arms very narrow and strongly compressed 

 laterally; a prominent narrow, usually low, keel runs the entire 

 length of the division series and arms; the lateral borders of 

 the ossicles of the division series and of the arm bases bear 

 coarse irregular spines; the proximal cirrus segments have a 



SIBOGA-EXPEDITIE XLIl/'. 19 



