A MONOGRAPH OF THE EXISTING CRINOIDS 25 



PI is much enlarged, and is much larger than the pinnules succeeding. It is com- 

 posed of 12 segments of which the third is greatly broadened. From this it tapers to 

 the base, and also distally, the terminal five segments being exceedingly small. 



Notes. The second specimen resembles that described, except that the spinosity 

 of the dorsal pole of the centrodorsal is much less developed; there are 32-34 cirrus 

 segments. 



These specimens are evidently young, and the characteristic features of the 

 species have not as yet become fully accentuated. 



Locality. Dr. Th. Mortensen's Pacific expedition, 1914-1916; 7 miles south of 

 Olutanga Island, east of Zamboanga, Mindanao, Philippine Islands; about 548 meters; 

 hard bottom; March 3, 1914 (2, C. M.). 



DAIDALOMETRA ARACHNOIDES (A. H. Clark) 



PLATE 3, FIGURE 12 

 [See also vol. 1, pt. 1, fig. 205, p. 239; pt. 2, fig. 744, p. 349.] 



Stenometra arachnoides A. H. CLARK, Proc. U. S. Nat. Mus., vol. 36, 1909, p. 402 (description; 

 Albatross station 5154; ?Port Denison, Queensland). 



Stiremetra arachnoides A. H. CLARK, Die Fauna Siidwest-Australiens, vol. 3, Lief. 13, 1911, p. 440 

 (range), p. 443 (range on east coast); Mem. Australian Mus., vol. 4, 1911, p. 721 (south to Port 

 Denison), p. 789 (synonymy; history; range) ; Crinoids of the Indian Ocean, 1912, p. 213 (synon- 

 ymy; localities); Internal. Rev. gesamt. Hydrobiol. Hydrogr., 1915, p. 223 and following (dis- 

 tribution in Australia). 



Stenometra acula A. H. CLARK, Zool. Anz., vol. 39, No. 11/12, 1912, p. 428 (description; Siboga station 

 294); Unstalked crinoids of the Siboga-Exped., 1918, p. 157 (identity). 



Daidalometra acuta A. H. CLARK, Journ. Washington Acad. Sci., vol. 6, No. 5, 1916, p. 116 (range). 



Daidalomelra arachnoides A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. 157 (in key 

 range; synonymy; notes; stations 166, 294), pp. 273, 275 (listed), pi. 23, fig. 60. 



Diagnostic features. The cirri are short, not more than half the arm length, with 

 49-65 segments; and the elements of the division series and first two brachials have a 

 narrow, sharp, and moderately high median carination and abruptly everted and 

 coarsely spinous edges. The 10-18 (usually 10-13 and most commonly 10) arms are 

 60 mm. long, and the cirri are 20-30 mm. long 



Description. The centrodorsal is moderate in size, columnar, broader basally than 

 long, decreasing slightly in width distally. The bare polar area is 2 mm. in diameter. 

 The cirrus sockets are arranged in 10 closely crowded columns of 2 each. 



Cirri XX (XII in the type), 61-65, 30 mm. long. The first 4 segments are subequal, 

 averaging twice as broad as long, rather prominently overlapping all around. The 

 fifth segment is nearly half again as long as broad, a more or less marked transition 

 segment. The sixth is of about the same length or slightly shorter. The next 5 

 segments are about as long as broad, and those succeeding gradually decrease in length 

 so that those in the distal half of the cirri are twice as broad as long or even slightly 

 shorter. The fourteenth or fifteenth and following segments bear prominent dorsal 

 spines. 



The disk and ambulacra are well plated. 



The ends of the basal rays are visible as dorsoventrally elongate tubercles in the 

 interradial angles of the calyx. 



843803 50 3 



