A MONOGRAPH OF THE EXISTING CRINOIDS 621 



The number of muscular articulations in the second intersyzygial interval is 

 given as follows: 3 (once), 4 (twenty-one times), and 6 (once). 



In the distal intersyzygial interval there is a tendency to an increase rather than 

 to a decrease in the number of muscular articulations, 5 occurring much more 

 commonly than 3. 



Carpenter noted that the oral pinnules differ considerably from those of typical 

 polymorpha. Not only are tliey much stouter, but their terminal combs are differently 

 constituted. The lower processes gradually develop from the outer margin of the 

 ventral surface of each calcareous segment, but toward the end of the pinnule they 

 gradually come to rise less and less from the outer margin and more and more from 

 the median portion of the ventral surface of each segment until finally, on the last 

 2 or 3 segments, they are developed from the inner margin. Consequently the comb, 

 when viewed from above, is seen not to lie altogether on the outer side of the pinnule 

 as is usually the case, but to start from the outer side, cross its ventral surface, and 

 finally come to lie on the inner side of each pinnule; that is, on the side nearest the 

 arm. 



Carpenter in 1882 mentioned having seen in the Dresden Museum some fine 

 individuals of the form which he described as me.yeri which had been collected in the 

 Philippines by Dr. A. B. Meyer. 



In the specimen from the Bonin Islands recorded by Gisl6n the centrodorsal is 

 flattened and is 4 mm. in diameter. The cirri are arranged in a single marginal row. 

 The dorsal pole of the centrodorsal is 3 mm. across. 



The cirri are XV, 15, 9 or 10 mm. long. The first and second segments are 

 broader than long, the third is about as long as broad, and the fourth and following 

 are longer, slightly constricted centrally, the sixth being the longest, half again as 

 long as broad. 



The distal segments are one-third again as broad as long. From the seventh or 

 eighth onward a weak and indistinct dorsal prominence is developed. In their distal 

 portion the cirri are somewhat compressed laterallj' and in a lateral view appear to 

 broaden shghtly. The terminal claw is short, stout, and a little longer than the 

 penultimate segment. The cirri are relatively small and weak. 



The radials project somewhat at the interradial angles. The IBri are in lateral 

 contact. They are wider distally than proximally, and are five times as broad as 

 long. The IBrj (axillaries) are low pentagonal, three times as broad as long, laterally 

 in contact with their neighbors. The IIBr and IIIBr series are 4 (3 + 4). The first 

 segments following each axillary are interiorly united. The division series and arm 

 bases are smooth and close together. 



The 40 arms are from 80 to 120 mm. long. The posterior arms are shorter and 

 stouter than the anterior, and their pinnules often lack ambulacral grooves. The 

 first 7 brachials are oblong, and those following have oblique ends. The outer 

 brachials have the distal ends slightly thickened. There are 14 brachials for each 

 10 mm. of arm length, or 11 if the syzygial pairs are coimted as units. The width 

 of the arms proximally is 2.5 mm. and distally 1 mm. or less. 



Syzygies occur between brachials 3+4, 11 + 12, 16+17, etc., and distally at 

 intervals of 4 muscular articulations. 



