MONOGRAPH OF THE EXISTING CRINOIDS. 



283 



this direction; but the combined possibilities of motion between the short outer 

 segments (when numerous) is such that the cirrus tips may be rolled up into a 

 close spiral, thus surrounding and clinging fast to any slender object, such as the 

 stem of a gorgonian or hydroid, which they may touch. 



The transverse ridges across the joint faces of the cirrals in the basal portion 

 of the cirri traverse the center of those joint faces (fig. 5876, pi. 13); this 

 accounts for the equal brevity of the ventral and dorsal profile of the very short 



FIG. 332. 



XEEE 



FIG. 333. 



FIG. 334. 



FIG. 335. 



FIGS. 332-335. 332, LATERAL VIEW OF A CIRRVS FROM A SPECIMEN OF ZYGOMETRA MICRODISCUS FROM NORTHERN AUSTRALIA 

 (AFTER P. H. CARPENTER). 333, A CIRRUS FROM A SPECIMEN OF ZYGOMETRA COMATA FROM SINGAPORE VIEWED (a) DOR- 

 SALLY AND (6) LATERALLY. 334, A CIRRUS FROM A SPECIMEN OP CATOPTOSIF.TRA HARTLAUBI FROM SOUTHERN JAPAN VIEWED 

 (a) DORSALLY AND (6) LATERALLY. 335, A CIRRUS FROM A SPECIMEN OF AMPHIMETRA PHTLTBERTI FROM THE ANDAMAN ISLANDS 

 VIEWED (a) DORSALLY AND (4) LATERALLY. 



basal segments, and the nondcvclopment of spines on the latter; as the segments 

 increase in length distally and become more and more compressed and carmate 

 dorsally the ridges gradually move nearer and nearer the ventral surface, so that the 

 ventral ligament pit becomes progressively smaller and smaller and the dorsal lig- 

 ament pit correspondingly increases in size, this being correlated with a correspond- 

 ing increase in the length and possible scope of the ligament fibers, as well as with 

 an increasing disproportion in the comparative strength of the two bundles as 

 explained above, and a progressive increase in the size of the dorsal spines or 

 processes. 



