NO. 5 TERTIARY ECHINOIDS FROM FLORIDA — KIER 33 



Adoral plate arrangement. — Plate sutures not visible on any speci- 

 men. 



Comparison with other species. — C. sunnilandensis is identical fn 

 all characters to C. subdepressus except that its anterior petal (III) 

 is open whereas in C. subdepressus it is closed. I examined 35 speci- 

 mens of C. subdepressus, and in all these specimens the anterior 

 petal was closed, whereas in all the 12 specimens of C. sunnilandensis 

 in which this area was exposed the petal was open. 



Occurrence. — Tamiami limestone, loc. 9, 10. 



Types. — Holotype, U.S.N.M. 648135, loc. 9; figured specimen, 

 U.S.N.M. 648134, loc. 9. 



ENCOPE MICHELINI L. Agassiz 



Encope michelini L. Agassiz, 1841, Monographies d'echinodermes . . . , Mon. 2, 

 p. 58, pi. 6a, figs. 9, 10. 



Encope michelini L. Agassiz. Mortensen, 1948, Monograph of the Echinoidea, 

 vol. 4, pt. 2, p. 441, pi. 70, fig. 23. (See this reference for the pre-1948 refer- 

 ences to this species.) 



Encope michelini L. Agassiz. Cooke, 1959, U.S. Geol. Surv. Prof. Paper 321, 

 p. 49, pi. 18, figs. 2, 3. 



Encope michelini L. Agassiz. Cooke, 1961, Smithsonian Misc. Coll., vol. 142, 

 No. 4, p. 17, pi. 6, figs. 5-6 ; pi. 7, fig. 5. 



ENCOPE MICHELINI IMPERFORATA Kier, new subspecies 



Plate 5, figure 1 ; Plate 6, figures 3, 4 ; text figures 25-30 ; table 2 



Diagnosis. — Subspecies distinguished from nominate subspecies 

 by absence of posterior interambulacral lunule in many specimens. 



Material. — Sixteen specimens. 



Shape. — From 82 to 140 mm long. Broad with width varying from 

 94 to 101 percent (average 96) of length ; test very low varying from 

 7 to 12 percent (average 9) of length; greatest width posterior to 

 center, anterior margin rounded, posterior sharply truncated; great- 

 est height posterior to center ; ambulacral notches well developed on 

 some specimens (text figs. 25, 30), absent on others; posterior closed 

 interambulacral lunule present in six of twelve specimens preserving 

 area where it would occur, irregularly developed, in some specimens 

 opening very small (text fig. 26), in others quite large (text fig. 28), 

 usually irregular in shape, unsymmetrical ; in one specimen opening 

 in adapical surface but none in adoral; in six specimens no lunule 

 (text figs. 25, 29, 30) ; adoral surface flat to slightly depressed except 

 for slight elevation between peristome and periproct; margin sharp. 



Apical system. — Slightly anterior, madreporite large, star shaped, 



