A MONOGRAPH OF THE EXISTING CRINOIDS 195 



DECAMETRA PARVA (A. H. Clark) 



PLATE 22, FIGURE 113 



Promelra parva A. H. CLARK, Ann. Mag. Nat. Hist., ser. 8, vol. 10, 1912, p. 39 (description; Siboga 

 station 315). 



Decametra parva A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. viii (discovery by 

 the Siboga and its significance), p. 118 (in key; range), p. 121 (detailed description; stations 

 260, 315; also Albatross station 5557), pp. 275, 276 (listed), pi. 20, fig. 46. 



Diagnostic features. The cirri are about 5.5 mm. long with 14 or 15 segments of 

 which the sixth or seventh and following are about as long as broad ; P 2 is much larger 

 and stouter than the other pinnules, though not greatly enlarged, with 11 segments; 

 PI, which is about two-thirds as long as P 2 , also has 11 segments; P 3 is small and weak, 

 much shorter than P! ; the arms are 40-45 mm. long. 



Description. The cirri are XIV, 14-15, 5.5 mm. long, resembling those of D. 

 minima; the sixth or seventh and following segments are about as long as broad. 



The 10 arms are about 40 mm. long. The lower oblong brachials are smooth, but 

 those following have rather strongly everted distal ends. 



P! is 2.3 mm. long, tapering rather rapidly in the first four segments and more 

 gradually from that point onward, composed of 11 segments of which the first is short, 

 the second is slightly longer, the third is slightly broader than long, the fourth is 

 slightly longer than broad, and the fifth and following are about twice as long as 

 broad. P 2 is from 3.5 to 4.5 mm. long, evenly tapering, much larger and stouter than 

 the other pinnules though not greatly enlarged, with ll'segments of which the first is 

 short, the second is half again as broad as long, the third is slightly broader than long, 

 and those following gradually increase in length to the seventh which, with those 

 succeeding, is twice as long as broad; the pinnule is rather strongly prismatic and the 

 fourth and following segments have their distal edges produced at the prismatic 

 angles into prominent short stout spines which increase in prominence distally. P 3 is 

 1 .5 mm. long, small and weak, composed of 8 segments of which the distal are elongated. 

 P 4 is slightly smaller than P 3 . The distal pinnules are exceedingly slender, from 4 to 

 4.5 mm. long, with 13 segments of which the second and third are slightly carinate and 

 the outer are greatly elongated. 



Notes. The specimen from off the Goto Islands seems to agree in all particulars 

 with others from farther south. 



The specimen from Port Galera, Mindoro, has the arms 45 mm. long. 

 In one of the specimen from the Danish Expedition to the Kei Islands station 101 

 the arms are 43 mm. long, the cirri have 14 or 15 segments, and P 2 has 11 segments. 

 Localities. Off the Goto Islands, Korean Straits (lat. 3310'05" N., long. 

 12918'07" E.); 77 meters; Capt. H. Christiansen, SS. Nordiske, Arpil 9, 1913 (1). 



Dr. Th. Mortensen's Pacific expedition, 1914-1916; Port Galera, Mindoro; 

 about 9 meters; February 3, 1914 (1). 



Albatross station 5557; in the vicinity of Jolo (Sulu), Philippines; Cabalian Point 

 bearing N. 70 W., 5.2 miles distant lat. 551'30" N., long. 12101'00" E.) ; 24 meters; 

 sand and coral; September 17, 1909 [A. H. Clark, 1918] (2, U. S. N. M., 36022). 



Siboga station 260; 2.3 miles N. 63 W. from the northern point of Nuhu Jaan, 

 Kei Islands (lat. 536'30" S., long.' 13255'12" E.); 90 meters; sand, coral, and 

 shells; December 16-18, 1899 [A. H. Clark, 1918] (2, U. S. N. M., E. 453; Amsterdam 

 Mus.). 



