

C'lMNulhKA 



125 



tin- dicvdic forms ;iiv properly termed //i/sr//x, and tin- lower Berjea nii' 



The basals as thus defined are e<|ui\ alent to tin- " parabasals " in 



Fro. 219. 



S S/l!l'- 



Lng. staik.-d 



Crin.ii.l with dieyHir 



ad anal inter- 



radius. ". Anals; I, 



b, [nfrabasals. 



(Ki-hi and left sides 



. atVr Au- 



gdin.) 



Arti i/ni'ri a us jn'iilxisi-liliuH.-i, Hall. Pro- 

 jection of calyx showing the three kisal* 

 (b), 5x3 simple radials (?), four paired inter- 

 rays (/()) ni"l ;l lit'th unpaireil anal interray (") 



Fi'.. -J-J1. 



I'nti-riiii'i'in us in ulti jili'f, 

 Traut. Calyx with <liey- 

 clic base, radials, costiils, 

 and distiehals. 



' subradiale " of do 



tin- older nomenclature of Johannes Miiller, and to the 

 Koninck and other authors. 



Both K-isals and infraliasals are: primarily five in number; but owing to the 

 fusii in of two or more of the proximal plates, the number of basals in the 

 niiHHK-yclic forms may be reduced to four, three, or even to two, and that >f 

 infrabasalfl in the dicyclic to three. During the 

 ontogenetic development of the recent Antedon, a 

 UK m- or less complete resorption of the basals has 

 lift-n olscr\fd ; and tin- same probably also held 

 true tor certain Mesozoic genera (A 1 /^-// ///'//'////.<, 

 In many of the non-pedunculate 

 (/'////"'//////>, Marsupites, Fig. 222) an 

 additional plate known as the / ntmdwsal rests 

 against the infraliasals, and jjj-i.baldv represents 

 an atrophied stalk. The Itasals ar- united with 

 one anot her and with the overlying radials l*v 

 close sutures, and are immovably held together 

 ly tihrnus connecti\e tissue. 'ITimgh usually 

 sim mill, the joint faces are sometimes striated, 

 and are visiKle externally as incised lines. 



/>. Succeeding the l>ase is a cycle of five (rarely four or six) plates, which, 

 on account of their position with reference to the rays, are called radials. The 

 radials form the sides of the calyx in nearly all Mesozoic and Recent Crinoids, 

 and give origin directly to the arms, which may become free immediately aliove 

 the radials, or may be incorporated for some distance in -the calyx, either by 

 means of supplementary plates, or by lateral suture among themselves. 



FK.. _'__'. 



Sehlot. sp. 



