1920] 



Kew: Cretaceous and Cenozoic Echinoidea 



81 



Related, forms. — This form resembles Astrodapsis tumidus Remond, 

 but differs in that the apical system is much more elevated, thus 

 giving the test a more distinctly conical a^ipearance ; ambulacral fur- 

 rows are not present on the under surface, and the superior surface 

 shows no interambulacral depressions. Its conical shape also distin- 

 guishes it from the other San Pablo species. It differs from Astro- 

 dapsis cicrhoensis Kew in its subpentagonal outline, in contrast to the 

 commonly elliptical outline of the latter; and from Astrodapsis {?) 

 pabloensis (Kew) in its smaller size and the greater thickness of the 

 test. 



Geologic horizon. — Upper San Pablo group. Upper Miocene; asso- 

 ciated with Astrodapsis tumidus Remond and Astrodapsis tumidus 

 (small thick form). 



Locality. — Mt. Diablo region, Univ. Calif, loc. 1950 (holotype). 



ASTEODAPSIS ANTISELLI Conrad 

 Plate 19, figures 2a, 2b, 2c 



Astrodapsis antiseUi Conrad. Proc. Acad. Nat. Sci. Phila., vol. 8, 1856, 

 p. 315; U. S. Pac. E. E. Expl. Eept., vol. 7, 1857, p. 196, pi. 10, figs. 1, 2. 



Astrodapsis antiseUi. Meek, Smithson. Misc. Coll., vol. 7, no. 183, 1864, 

 p. 2. 



Astrodapsis antiseUi. Gabb, Calif. Geol. Surv., Pal., vol. 2, 1869, p. 110. 

 Astrodapsis antiseUi. Cooper, Seventh Eept. State Mineralogist California, 

 1887, p. 270. 



Astrodapsis antiseUi. Merriam, Univ. Calif. Publ. Bull. Dept. Geol., vol. 2, 

 1898, pp. 110, 112. 



Astrodapsis antiseUi. Arnold, Proc. U. S. Nat. Mus., vol. 34, 1908, pi. 35, 

 fig. 10. 



Astrodapsis antiseUi. Arnold, U. S. Geol. Surv. Geol. Atlas, Santa Cruz 



folio (no. 163), 1909, pi. 2, fig. 58. 

 Astrodapsis a7itiseUi. Stefanini, Boll. Soc. geol. ital., vol. 30, 1911, p. 702. 

 Astrodapsis antiseUi. McLaughlin and Waring, Calif. State Min. Bur. 



Bull., no. 69, 1914, map folio, fig. 37. 

 Astrodapsis antiseUi. Clark and Twitehell, U. S. Geol. Surv. Mon., vol. 54, 



1915, pp. 198-199, pi. 94, figs. 3, 4a, 4&. 



Holotype. — No. 165466a. U. S. Nat. ]\Ius. ; figured specimens, nos. 

 11372 and 11373, Univ. Calif. Coll. Invert. Pal. 



Test of medium size. Measurements of specimen 11373 Univ. Calif. 

 Coll. Invei't. Pal. : anteroposterior diameter 60 mm., transverse diam- 

 eter 50 mm., greatest height approximately 12 mm. Subcircular to 

 suboval in outline ; upper surface considerably depressed ; margin 

 thickened and rounded, and with very slight notching in the posterior 



