MONOGRAPH OF THE EXISTING CRINOIDS. 



283 



this direction; but the cdinbincd 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 chnging fast to any slender object, sucli as the 

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



The transverse ridges across the jomt faces of the cirrals iu the basal jjortion 

 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 s^cry short 



FlO. 332. 



sniEiEEEEEEEEEIXlIEEEXniIIII 



Fio. 333. 



xzm: 



=c=ar]^3rnnr]xtIII 



Fig. 334. 



a.i .H.i.i.H-i-i-i-i- i-i-i-i-i-M-i-i» i^|<- 1: L [JUL 



Fig. 335. 

 Figs. 332-335.-332, L.vteeal mew of a cirrus from a specimen of Zygometea microdiscus from northern Austeaua 



(AFTER P. H. C.\RPE>»TER). 333, A CIRRUS FROM A SPECIjrEN OF ZyGOMETRA COMATA FROM SdJCAPORE STEWED (o) DOR- 

 S.UXY AND (6) LATERALLY. 334, -^ CIRRUS FROM A .SPECIMEN OF CaTOPTOMETEA IIARTLAUHI FROM SOUTHEEN JAPAN MEWED 

 (d) DOESALLY AND (6) LATEE.U.LY. 335, A CIRRUS FROM A SPECIMEN OF AMPHIMETEA PUILIDEKTI FEOM THE AND.VMAN ISLANDS 

 VIEWED (O) DORSALLY AND (6) LATERALLY. 



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

 increase in length distally and become more and more comjiressed and caruiate 

 dorsally the ridges gi'adualiy 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. 



