110 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



A. [Cyllometra] manca). HAMANN, Bronns Klassen und Ordnungen des Tier-Reichs, vol. 2, 

 Abt. 3, 1907, p. 1581 (listed). A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 37 (= Cyllo- 

 metra clarae). 



Antedon manca (part) A. H. CLARK, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 131 (considered as 

 including disciformis and clarae). 



Cyllometra manca (part) A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 350 (variabil- 

 ity), p. 357 (listed). 



Cyllometra clarae A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 6 (listed) ; Crinoids of 

 the Indian Ocean, 1912, p. 37 (identity), p. 158 (synonymy; Amboina). 



Petasometra clarae A. H. CLARK, Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 27 (compared with 

 P. helianlhoides) ; Die Fauna Sudwest-Australiens, vol. 4, Lief. 6, 1913, p. 313 (same); Un- 

 stalked crinoids of the Siboga-Exped., 1918, p. 113 (in key; range; references; notes; stations 

 50, 231), pp. 271, 274 (listed). GISLN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 

 II, 1934, pp. 20, 22, 23. 



Diagnostic features. There are 10-14 arms which are from 85 to 120 mm. long. 

 The cirri are VII-XXI, 19-29, from 12 to 17 mm. long. 



Description. The centrodorsal is a moderately large and thick disk with a circular 

 and slightly concave dorsal pole. The cirrus sockets are arranged in a single 

 marginal row. 



The cirri are XXI, about 25, about 17 mm. long. The component segments are 

 fairly equal. The proximal half of the cirri has a rather broad dorsal surface, but in 

 the distal half the cirri become more compressed laterally. From the second or third 

 onward the segments have a dorsal transverse ridge which at first lies almost at the 

 distal end but in the later segments becomes more median. In the distal more com- 

 pressed half of the cirri the transverse ridge passes over into a single small spine. The 

 opposing spine is stout. 



The radials are slightly visible. The IBr, are entirely free laterally. The IBr 2 

 (axillaries) are pentagonal and rather short. In the type specimen two of the post- 

 radial series bear each a IIBr series; one of these IIBr series is 2 and the other is 

 4 (3+4). The free outer borders of the division series are smooth, without lateral 

 processes. Slight synarthrial tubercles are developed. 



The 12 arms are about 100 mm. long. They have a smooth dorsal surface and are 

 composed of short brachials. The first brachials are almost rhombic, and are only 

 partially united interiorly. The second brachials are slightly shorter than the first. 

 The first syzygial pair (composed of brachials 3+4) is slightly broader than long. 

 The following five or six brachials are discoidal, and those succeeding are wedge- 

 shaped, toward the ends of the arms becoming blunter and finally more squarish. 



Syzygies occur between bracbials 3+4, again from between brachials 9+10 to 

 between brachials 14 + 15, and distally at intervals of from 5 to 9 muscular articula- 

 tions. 



P a is absent. PI is approximately as long as P 2 and P b , which are rather slender, 

 7 mm. long, and are composed of 15-20 cylindrical segments which, with the exception 

 of the basal, are as long as broad. The pinnules following are markedly shorter; 

 from P 6 on the length of the pinnules increases, reaching 12 mm. distally. 



The disk, which is only slightly incised, reaches as far as the first syzygial pair. 

 Sacculi are numerous. 



The disk is a beautiful red-brown with small and large white spots ; the cirri and 



