418 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



spine that extends over the base of the following segment; cirri less numerous, usually XX- 

 XXV; 20-30 (typically about 30) arms. 



ft 1 . Proximal portion of the animal broad, the division series and arm bases as far as the seventh 

 brachial at least as seen in lateral view diverging rapidly, at an angle of approximately 90; 

 color in alcohol uniform brown. 



c 1 . Cirri shorter and more slender, 50 mm. long with 86 segments; arms 80 mm. long (Philip- 

 pines; 68 meters) splendida (p. 420) 



c>. Cirri longer and stouter, 75-77 mm. long with 99-113 segments (Cochin China to Celebes; 



5-80 meters) . . venusta (p. 418) 



V. Proximal portion of the animal very narrow, the division series and arm bases as seen in lateral 

 view diverging very slowly, at an angle of about 45 ; color in alcohol violet or purple, blotched 

 and variegated with white (Bonin and Philippine Islands southward to the Kei Islands; 

 68-106 [?183] meters).. trichopoda (p. 421) 



PTEROMETRA VENUSTA A. H. Clark 



PI/ATE 43, FIGURE 220 



Plerometra venusta A. H. CLARK, Zool. Anz., vol. 39, No. 11/12, 1912, p. 424 (description; Siboga 

 station 117); Unstalked crinoids of the Siboga-Exped., 1918, p. 143 (in key; range; detailed 

 description; station 117), p. 273 (listed), pi. 22, fig. 59. GISL&N, Kungl. Fysiogr. Sallsk. Lund 

 Forh., vol. 7, No. 1, 1936, p. 5 (French Indo-China), p. 6 (range), p. 19 (Pulo Condor; notes) 



Diagnostic features. The earlier cirrus segments have the ventral portion of the 

 distal edge raised and overlapping the bases of the segments succeeding with the mid- 

 ventral portion produced into a long sharp spine; the division series and arm bases 

 are evenly rounded dorsally and are broad, diverging regularly from the centro- 

 dorsal at an angle of about 90; the cirri are XX-XXXIV, 99-113, 75-77 mm. long; 

 the 22-28 arms are about 95 mm. long. 



Description. The centrodorsal is thick discoidal or columnar, the sides nearly 

 parallel, 6 mm. broad at the base and 2.5 mm. high. The cirrus sockets are arranged 

 in 10 equally spaced columns, each column separated from its neighbors on either side 

 by a shallow groove from one-fourth to one-third of a cirrus socket in width. There 

 are 2, more rarely 3, cirrus sockets to a column. The dorsal pole of the centrodorsal 

 bears a rosette of five prominent tubercles. 



The cirri are XX-XXV, 99-113 (usually nearer the latter), 77 mm. long, stout 

 basally and tapering slightly distally, though this distal taper is more gradual than in 

 Pterometra trichopoda and therefore not so marked. The longest cirrus segments 

 are from one-third to one-half again as long as broad. In the earlier segments the 

 ventral distal edge is rather prominent; after the eighth the median portion begins 

 to project, overlapping the base of the next succeeding segment, this after the eleventh 

 or twelfth becoming a sharp ventral spine which persists as far as the twentieth, or 

 even the twenty-third, segment. At first this ventral spine makes a considerable 

 angle with the longitudinal axis of the segments, but distally its outer part becomes 

 more nearly parallel to it. The cirri are more broadly rounded ventrally than are 

 those of P. trichopoda, and there is no well developed sharp ridge or keel extending 

 back from the ventral spine along the midventral line of the segments. The dorsal 

 processes arise very slowly, and are never very prominent. They first appear on 

 about the twenty-third segment. The cirri are moderately compressed laterally, 

 less so than in P. trichopoda. 



The radials and division series resemble those of P. splendida, but the division 

 series are slightly more robust. 



