NO. 4 ECHINOIDS, TRINIDAD AND VENEZUELA — COOKE I9 



evenly curved, those of the other petals incurved near the distal tips. 

 Peristome under the apical system. Periproct elongated, closer to the 

 lunule than to the peristome. 



Length of holotype 109 mm. ; width 105 mm. ; height 12 mm. 



Occurrence. — Venezuela: Rio Seco area, Falcon (Creole Petroleum 

 Co. V-2635, 72466 (holotype), 72468 (paratypes), 72480, 72482), 



Geologic horizon. — Pliocene : San Gregorio formation. One lot 

 from the Miranda district is referred by the label to the Codore forma- 

 tion, another to the Chiguaje formation, both of late Miocene age. 



Comparisons. — The petals of Encope secoensis resemble those of 

 Encope micropora Agassiz (1841, p. 50, pi. loa, figs. 4-8; pi. 19a, 

 fig. 7), but its ambulacral notches are usually open, like those of 

 Encope emarginata (Leske) (Cooke, 1959, p. 49, pi. 17, fig. 5 ; pi. 18, 

 fig. i), which, however, is highest behind. Encope secoensis appears 

 to be closely related to E. sverdrupi Durham (1950, p. 48, pi. 37, 

 fig. 6; pi. 39, figs. 4, 6), from the lower Pliocene of Santa Inez Bay, 

 Baja California, but the petals of the holotype of that species are less 

 broadly rounded. This may be an individual feature, for there is some 

 variation in the curvature of E. secoensis, some of whose petals 

 approximate the shape of E. sverdrupi. 



ENCOPE (MELITELLA) FALCONENSIS Cooke, n. sp. 

 PI. 8, figs. 2-4 



Horizontal outline subcircular, truncated behind. Highest point 

 central. Apical system central, star shaped, rather large ; five genital 

 pores. Petals short, nearly equal in length, extending halfway to the 

 margin ; half as wide as long ; poriferous zones evenly rounded ; inner 

 pores circular, outer pores elongated, diagonal. Ambulacral notches 

 closed in the type, open in smaller individuals. Posterior lunule oval, 

 near the margin. Peristome small, central, pentagonal. Periproct 

 elongated, midway between the peristome and the margin. Ambulacral 

 grooves conspicuous. 



Length of holotype 61 mm. ; width 6^ mm.; height 9 mm. 



Occurrence. — Venezuela: Rio Seco area. Falcon (Creole Petroleum 

 Co. V-2651, 72465, 72473, 72715 (holotype)). 



Geologic horizon. — Miocene and Pliocene : Chiguaje formation, of 

 late Miocene age (type). San Gregorio formation, of Pliocene age. 



Holotype.— IJS1<\M 638633. 



Comparison. — This species appears to resemble Encope (Melitella) 

 stokesii Agassiz (1841, p. 59, pi. 6a, figs. 1-8), living off the Galapagos 

 and along the west coast of tropical America, and may prove to be the 



