A MONOGRAPH OF THE EXISTING CRINOIDS 225 



of the immaturity of the type specimen of garrettiana hi contrast with the full maturity 

 of the described specimens of bocki. 



Prof. Torsten Gisle"n described Diodontometra bocki as follows. 



The centrodorsal is conical, pointed, 3.0 mm. hi diameter at the base and 3.5 mm. 

 high. The cirrus sockets are arranged hi five midradial groups separated by interra- 

 dial interspaces which are almost as broad as the areas occupied by the cirri. In 

 each midradial group there are 5 or 6 closely crowded sockets, often forming an almost 

 single row. 



The cirri are XXVI, 15-17, from 15 to 20 mm. long, the smaller apical cirri with 

 1012 segments and 5 or 6 mm. long. The first and second segments are short, the 

 third is about as broad as long, the fourth is longer, the fifth to seventh are two-thirds 

 again as long as broad, and the eighth or ninth and those following to the antepenulti- 

 mate are not much longer than broad. The dorsal surface of the segments is slightly 

 carinate and the distal dorsal ends are somewhat overlapping. There are no dorsal 

 spines. The opposing spine on the distal portion of the penultimate segment is large, 

 bifurcate, and often has a small lateral accessory spine. The terminal claw is longer 

 than the penultimate segment and is slender, curved, and pointed. 



The radials are visible as narrow bands hi the interradial angles. The IBr] are 

 four times as broad as long and are in close lateral apposition hi the proximal half; 

 they are narrowed hi the midradial line by the posterior projection of the axillary. 

 The IBr 2 (axillary) is pentagonal, twice as broad as long, like the IBri with a slight 

 median carination but otherwise rounded dorsally. The IIBr series are 2 and resemble 

 the IBr series. The ossicles immediately following the axillaries are hi close lateral 

 apposition in the proximal half. 



The 19+ (probably originally 20) arms are 60 mm. long; hi four cases they are 

 broken off at the synarthrial articulation between the first two brachials. The first 

 two brachials have a slight synarthrial tubercle. The first 12 brachials are discoidal, 

 those following becoming wedge-shaped. The fifth to tenth brachials have the distal 

 ends a little overlapping, those following being smooth. The arms are laterally flat- 

 tened as far as the fourth brachial. Seven or 8 of the terminal brachials bear rudi- 

 mentary pinnules. 



Of the two arms given as samples of the distribution of the syzygies by Gisl6n, one 

 has the first four brachials united hi two synarthrial pairs and the syzygies between 

 brachials 21+22, 31+32, and 41+42. The other also has the first four brachials 

 united hi two synarthrial pairs and syzygies between brachials 17 + 18, 26+27, 35+36, 

 and 44+45. 



PI is 3.5 mm. long with 13 segmeats. P 2 is 4.5 mm. long with 12 segments. P 3 

 is 4 mm. long with 11 segments. P 4 is 3.5 mm. long with 10 segments. The segments 

 on the first three pinnules are rather uniform, from twice as broad as long to as long 

 as broad; on the outer side of the third and following segments there are small wing- 

 like flanges partly caused by small notches between the segments. On P 3 to P ]2 , 

 which are 3.5 to 4 mm. long with 10 or 11 segments, the third to fifth or sixth seg- 

 ments are flattened dorsoventrally, cup-shaped with winglike borders; the seventh to 

 eleventh segments are narrow and long again. In dorsal view the cup-shaped seg- 

 ments are about as long as broad, the distal over twice as long as broad. The distal 

 pinnules are 4 mm. long with 1 1 segments of which the first is short, the second is about 



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