NO. 4 ECHINOIDS, TRINIDAD AND VENEZUELA — COOKE I7 



behind, others are elHptical in horizontal outline, like the type of 

 Clypcastcr kuglcri, which agrees well in such other features as can 

 be determined from the figures. There is some variation also in the 

 degree of swelling of the interporiferous zones. The wide petals 

 with strongly incurved tips are characteristic. 



Occurrence. — Venezuela: Goajira Peninsula, Zulia (Creole Petro- 

 leum Co. 13418). Near Castilletes, Goajira Peninsula (Creole Petro- 

 leum Co. 81046). Quebrado Cojoro, Goajira Peninsula, Paez district, 

 Zulia (B-2305). Punta Carnero, Isla Margarita (Creole Petroleum 

 Co. 79055). Rio Motoruco, La Vela de Coro, Falcon (B-2771). Rio 

 Coro, Falcon (Creole Petroleum Co. 56929). Near southwest edge of 

 Cumarebo field. Falcon (Creole Petroleum Co. 59953). 



Geologic horizon. — Miocene to Recent. 



Figured specimen. — USNM 638630 (Creole Petroleum Co. 13418). 



ENCOPE MICHELINI Agassiz 



PI. 6, figs. 5-6; pl. 7, fig. 5 



Encope michclini Agassiz, 1841, Monographies d'echinodermes, Monogr. 2, p. 58, 



pl. 6a, figs. 9-10. 

 ^Encope platytata Jackson, 1917, Proc. U. S. Nat. Mus., vol. 53, No. 2218, pl. 67, 



figs. 1-2, text fig. 2. 

 Encope wicdenmayeri Jeannet, 1928, See. Paleont. Suisse Mem., vol. 48, p. 20, 



pl. 3, figs. 1-4, text fig. 3. 

 Encope michelini Agassiz. Cooke, 1959, U. S. Geol. Surv. Prof. Pap. 321, p. 49, 



pl. 18, figs. 2-3. 



This common Recent species is variable in many features, notably 

 the height of the posterior part, which ranges from slightly higher 

 than the apical system to a protruding hump ; the depth of the 

 ambulacral emarginations ; the size and shape of the posterior lunule, 

 which ranges from circular to much elongated ; and the shape of the 

 petals, which in young individuals are more convex than when full 

 grown. 



A single fragment from the Gatun formation of the Canal Zone, 

 the holotype of Encope platytata Jackson, has convex poriferous zones 

 of the anterior paired petals much like those of the small Recent 

 specimen figured by Cooke (1959), but the discovery of topotypes 

 may show it to be different. 



There seems to be no doubt that the many Encopes in the collec- 

 tions from Venezuela here studied represent the same species as the 

 two fragments named Encope wiedenmayeri by Jeannet. Most of 

 them fall within the range of variation of Encope michelini, but 

 some of the fossils are larger than the living form. One fossil from 



