1920] Kew: Cretaceous and Cenozoic Echinoidea 151 



diverge to a greater degree and then converge close to the inner rows 

 at the end of the petal. Interporiferous areas as wide as the porif- 

 erous areas ; pores in both rows transversely elongate. Odd anterior 

 petal longer than tlie others and wider ; both rows of pores diverge 

 continuously to their extremities. All petals in deep sulci, the odd 

 anterior one continuing beyond the petal through a deep notch in the 

 ambitus to the peristome on the under surface. Lower surface faintly 

 convex. Peristome situated well forward in a strongly developed 

 transverse depression. A prominent labrum is present which is pro- 

 duced posteriorly into a moderately developed episternum. Periproct 

 small and round ; situated high up on the posterior part of the test. 

 Tubercles on upper surface very small and crowded ; larger and less 

 numerous on the under surface ; largest immediately anterior to the 

 peristome. 



Belated forms. — Schizaster lecontei Merriam ditfei's from S. diahlo- 

 efisis mainly in having a more elongate test, in that the petals of the 

 bivium. are slightly longer, and the apical system is central. 8. diablo- 

 ensis Kew may be separated from S. cordiformis Kew in having a more 

 tumid test, more eccentric apical system, and in that the posterior 

 end of the test is not so broadly truncated. 



Geologic henizon. — Common in Meganos group, Middle Eocene; 

 associated with Turritella andersoni Dickerson. 



Localities. — Type from SW. 14 of Sec. 11, northeast of Wall Point, 

 south side of Mount Diablo, Univ. Calif, loc. 1427 (108). Occurs also 

 at Marysville Buttes, Santa Ynez Mountains, and on both north 

 and south sides of Mount Diablo, California. 



SCHIZASTEE LECONTEI Merriam 



Plate 41, figures 3a, 3b, 3c, M 



Schizaster (?) sp. Merriam, Jour. GeoL, vol. 5, 1897, p. 773. 



Schizaster lecontei Merriam. Proc. Calif. Acad. Sci., ser. 3, GeoL, vol. 1, 



1899, pp. 164-165, pi. 21, figs. 1, la. 

 Not Schizaster lecontei. Dickerson, Univ. Calif. Publ. Bull. Dept. Geol., 



vol. 8, 1914, pp. 121-122, pi. 6, fig. 7. 

 Schizaster lecontei. Stefanini, Boll. Soc. geol. ital., vol. 30, 1911, p. 697. 

 Schizaster lecontei. Clark and Twitehell, U. S. Geol. Surv. Mon., vol. 54, 



1915, pp. 151-152, pi. 69, figs. So., 3Z). 



Holotype. — No. 11026 ; figured specimen, no. 11341 Univ. Calif. 

 Coll. Invert. Pal. 



Test of small size. Average measurements : anteroposterior diam- 

 eter 22 mm., transverse diameter 20 mm., greatest height 14 mm. 



