A MONOGRAPH OF THE EXISTING CRINOIDS 101 



long with 13 segments. The pinnules followed gradually increase in length, the 

 forty-first pinnule being 9 mm. long with 19 segments. 



The disk is much incised, and the interradial areas are more or less covered with 

 rather large plates. The ambulacra as far as the last axillary are raised and strongly 

 plated ridges, but the ambulacra of the arms and pinnules are unprotected by plates. 



Sacculi are abundant, especially on the pinnules, and sometimes appear on the 

 outer ends of the plated disk ambulacra. 



Color in life.- Dr. H. L. Clark says that this species is, on the whole, much more 

 varied than Z. microdiscus, combinations of light grays, buffs, fawn-color, and purple 

 of various shades being usual, while unicolor specimens are rare. A specimen from 

 Darwin was distinctly dull purple and white, the disk whitish or pale cream color, 

 the pinnules tipped with white and also white on the dorsal side. 



Notes. The details of the eight specimens dredged by the Endeavour between 

 Fremantle and Geraldton are as follows: 



(1) 45 arms, 110 mm, in length. Of the 10 IIBr series present 9 are 4 (3+4) 

 and one is 2. Of the 20 IIIBr series present 17 are 2 and 3 are 4 (3+4). The 5 IVBr 

 series are all 4 (3+4) ; four of them are developed on the outermost side of the post- 

 radial series, the fifth being by the side of one of these. The centrodorsal is large, 

 thick discoidal, with the dorsal pole slightly concave and 5 mm. hi diameter. The 

 cirri are composed of 44-47 segments and are 30 to 35 mm. in length. P D is rather 

 slender, about 15 mm. long, and is composed of 27-29 segments. 



(2) 40 arms, about 100 mm. long. Of the 10 IIBr series 7 are 4 (3+4) and 3 are 2. 

 There are 16 IIIBr 4 (3+4) and 2 IIIBr 2 series; two of the IIIBr series are missing. 

 The cirri are composed of 37-42 segments and are 30 to 33 mm. long. P D is 18 mm. 

 long, rather slender, and is composed of 37 segments. 



(3) 40 arms, about 100 mm. long. The 10 IIBr series are 4 (3+4). Of the 18 

 IIIBr series 12 are 2 and 6 are 4 (3+4). The 2 IVBr series are 4 (3+4). The cirri 

 are composed of 38-39 segments and are about 30 mm. long. The elongate proximal 

 pinnules are slender. 



(4) Two of the postradial series are missing. The 3 postradial series present 

 each bear 8 arms, 2 IIBr series and 4 IIIBr series being present in every case. All 

 of the IIBr series are 4 (3+4). Nine of the IIIBr series are 2 and 3 are 4 (3+4). 



(5) 38 arms. One of the IIBr series is missing. The 9 IIBr series are 4 (3+4). 

 Of the IIIBr series 10 are 2 and 6 are 4 (3+4). 



(6) 36 arms, about 100 mm. in length. The 10 IIBr series are 4 (3+4). Of 

 the IIIBr series 9 are 2 and 7 are 4 (3+4). The cirri are composed of 34-42 segments 

 and are 25 to 35 mm. long. 



(7) 36 arms, about 100 mm. long. Of the 10 IIBr series 5 are 4 (3+4) and 5 are 2. 

 Of the IIIBr series 8 are 2 and 8 are 4 (3+4). The cirri are composed of 36-40 seg- 

 ments and are 25 to 30 mm. long. 



(8) 34 arms, about 100 mm. in length. The 10 IIBr series are 4 (3+4). The 

 14 IIIBr series are 2. The cirri are composed of 36-43 segments and are 25-30 mm. 

 in length. 



The color of these specimens in life was recorded as very variable. 

 The specimen probably from the vicinity of Perth has 38 arms, which are about 

 110 mm. long. All the IIBr series are 4 (3+4). Of the IIIBr series 11 are 2 and 7 



