A MONOGRAPH OF THE EXISTING CRINOIDS 193 



tion and, with the arm bases, more or less flattened against each other. The 

 brachials are of the typical short discoidal type and have strongly produced distal 

 edges. The distal edges of the elements of the division series are also slightly pro- 

 duced and finely spinous. 



The details of the arm division are as follows: 



Ray 1 : Two IIBr series of 2 each; that to the left (as viewed dorsally) bears 

 externally (on the left) a IIIBr series of 2, and internally (on the right) an undivided 

 arm. Both of the undivided arms arising from the IIIBr series have the first syzygy 

 between brachials 2 + 3, but the (internal) undivided arm arising from the IIBr 

 series has the first syzygy between brachials 3 + 4. The IIBr series to the right bears 

 internally (toward the left) an undivided arm on which the first syzygy is bteween 

 brachials 3 + 4, and externally (toward the right) a IIIBr 5 (4 + 5; series the 2 

 derivatives from which have the first syzygy between brachials 2 + 3. The total 

 number of arms on this ray is 6, arranged in 2, 1, 1, 2 order. 



Ray 2: Two IIBr series of 2 each; that to the left bears 2 undivided arms on 

 which the first syzygy is between brachials 3 + 4. That to the right bears inwardly 

 (toward the left) a IIIBr 4 (3 + 4) series, both derivatives from which have the first 

 syzygy between brachials 2 + 3, and outwardly (toward the right) an undivided 

 arm on which the first syzygy is between brachials 3 + 4. The total number of 

 arms on this ray is 5, arranged in 1 , 1 , 2, 1 order. 



Ray 3 : Two IIBr series of 2 each ; that to the left bears externally (toward the 

 left) an undivided arm on which the first syzygy is between brachials 2 + 3, and 

 internally (toward the right) 2 IIIBr series all 4 derivatives from which have the 

 first syzygy between brachials 2 + 3. The IIBr series to the right bears 2 undivided 

 arms on which the first syzygy is between brachials 2 + 3. The total number of 

 arms on this ray is 7, arranged in 1, 4, 1, 1 order. 



Ray 4: Two IIBr series, that to the right 4 (3 + 4), that to the left 2. The 

 IIBr 4 (3 + 4) series bears 2 IIIBr 3 (2 + 3) series; in the 4 derivatives from these 

 the first syzygy is between brachials 2 + 3 in all cases except on the innermost 

 arm (the furthest to the right) on which it is between brachials 15 + 16. The 

 IIBr 2 series bears 2 IIIBr 2 series; of these the inner (to the left) bears 2 IVBr 3 

 (2 + 3) series; the outer (to the right) bears inwardly (to the left) a IVBr 3 (2 + 3) 

 series and outwardly (to the right) an undivided arm. In all the derivatives from 

 this IIBr 2 series the first syzygy is between brachials 2 + 3. The total number of 

 arms on this ray is 11, arranged in 2, 2, 4, 3 order. 



Ray 5: Two IIBr series of 2 each; that to the left bears externally (to the 

 left) an undivided arm, and internally (to the right) a IIIBr 3 (2 + 3) series. That 

 to the right bears internally (to the left) an undivided arm and externally (to the 

 right) a IIIBr 2 series which bears internally (to the left) a IVBr 4 (3 + 4) series 

 and externally (to the right) an undivided arm. All the first syzygies in the arms 

 on this ray are between brachials 2 + 3. The total number of arms on this ray is 

 7, arranged in 1 , 2, 1 , 3 order. 



On the arms in which the first syzygy is between brachials 2 + 3 the first brachials 

 always bear pinnules; but on the arms in which the first syzygy is between brachials 

 3 + 4 the first pinnule is on the second brachial. 

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