66 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



1-4. BELL, Proc. Zool. Soc. London, 1894, p. 401 (comparison with A. moorei). HAMANN, 

 Bronn's Klassen und Ordnungen des Tier-Reichs, vol. 2, Abt. 3, 1907, p. 1581 (listed). HART- 

 LAUB, Mem. Mus. Comp. Zool., vol. 27, No. 4, 1912, p. 309 (in Spinifera group; history). 

 A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 34 (of P. H. Carpenter, 1888 = Parametra 

 compressa); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 81 (of P. H. Carpenter, 1888 = P. 

 compressa + P. granulata). 



Charitometra compressa A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 361 (listed); 

 Proc. Biol. Soc. Washington, vol. 21, 1908, p. 125 (should have been referred to Thalassometra) . 



Thalassometra compressa A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 125 (at first 

 wrongly referred to Charitometra) ; Proc. U. S. Nat. Mus., vol. 34, 1908, p. 225 (comparison with 

 Th. [Parametra] fisher i; systematic position). 



Parametra compressa A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 16 (listed); Crinoids 

 of the Indian Ocean, 1912, p. 34 ( = Antedon compressa P. H. Carpenter, 1888), p. 213 (synonymy; 

 range, in part [excluding Philippine Islands]); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, 

 p. 45 (published references to specimens in the B. M.; Challenger station 192; characters of the 

 division series and lower brachials); Unstalked crinoids of the Siboga-T,\ped. 1918, p. 158 (in 

 key; range; references; detailed description; station 302), p. 276 (listed). GISLEN, Ark. Zool., 

 vol. 19, No. 32, Feb. 20, 1928, p. 8, No. 33 (notes). 



Diagnostic jeatures. The arms beyond the proximal more or less oblong brachials 

 are distinctly carinate; the cirri are short, about one-fifth of the arm length, with the 

 transition segment the eighth and the distal segments broader than long with promi- 

 nent carinate processes or blunt dorsal spines; and the lateral portions of the elements 

 of the division series and first two brachials are smooth. The 15-20 arms are 120-140 

 mm. long, and the cirri are 23 mm. long with 16-20 segments. 



Description. The centrodorsal is discoidal with a bare flat polar area 3.5 mm. in 

 diameter. 



The cirri are XIV, 18-20, 23 mm. long. The first segment is very short, those 

 following gradually increasing in length to the fourth, which is slightly broader than 

 long, and the fifth-seventh, which are as long as, or very slightly longer than, broad. 

 The eighth, a transition segment, is about half again as long as the median width. 

 The ninth is about as long as the median width. The following segments gradually 

 decrease in length so that the last three or four before the penultimate are about twice 

 as broad as long. The distal dorsal edge of the eighth is thickened ; on the segments 

 succeeding this thickening soon becomes a thick rounded dorsal spine of the type 

 characteristic of the genus. 



The ends of the basal rays are visible as small but prominent rounded tubercles in 

 the angles of the calyx. 



The radials are concealed. The IBr! are very short, about twice as long on the 

 lateral border as in the median line, in lateral apposition for the basal two-thirds but 

 in the distal third diverging in nearly a straight line, extending well up in the angles of 

 the calyx; they bear a low blunt median carination. The IBr 2 (axillaries) are rhombic, 

 twice as broad as long, the lateral angles in contact with those of their neighbors ; the 

 cutting away of the distal angles of the IBri forms large and conspicuous water pores 

 just beneath the apposed angles of the axillaries; in the median line of the axillaries 

 there is a low blunt median carination ; from the lateral angles a horizontal ridge runs 

 inward for from one-third to one-half of the distance to the median line, sometimes in 

 the middle of the angle, sometimes toward the proximal side, where it branches, one 

 branch curving downward and becoming a produced proximal border which runs to 



