5° 6 



HERRICK E. WILSON 



anchylosed. In this group there are five possible combinations: 

 ab — c — d — e — , a — be — d — e — , a — b— cd — e — , a — b — c — de — , and N 

 b — c — d — . Of these combinations, a — b — cd — e — has been 



ea 



the only one described in the four-basal Melocrinidae; however, 

 the writer has found the a — be — d — c — (No. 2a) combination in 

 the following specimens in the Springer collection: of eight speci- 

 mens of Melocrinus calvini from Calloway County, Missouri, four 



Fig. 5. — Diagrams illustrating types of the possible combinations due to anchylosis 

 of two or more of the primitive nve-basals. 



could be properly oriented 1 , and these showed the be anchylosis 

 (PI. II, No. 4), as did two specimens of M. obconicus ? Hall, and one 

 of the type specimens of M. roemeri. The other four-basal forms 

 of the Melocrinidae( ?) and the Eucalyptocrinidae 2 have the 

 a — b — cd — e — type of base. 



Fig. 5, No. 3, illustrates a type in which three adjacent basals 

 have been anchylosed (abc — d — e — ). Here again hve combinations 



1 In orienting these specimens the anal tube was used as the reference point. 

 3 This orientation of Eucalyptocrinus is strictly arbitrary, as no indices for proper 

 orientation have as yet been discovered. 



