372 



University of California Publications in Geology [Vol. 8 



the posterior ambulacral areas. Ambulacra petaloid; petals slightly 

 elevated and wide open. Pores conjugate ; inner rows of rounded 

 pores extend to the margin in almost straight lines, converging but 

 little ; outer rows of elongated pores converge close to the inner rows 

 near the margin, where they become rounded and continue parallel 

 with the inner rows to the ambitus. Interambnlacral areas flat. Anus 

 inframarginal. Inferior surface flat and lacking ambulacral fur- 

 rows. Tubercles small and set close together. 



This form resembles Astrodapsis tumidus, but differs in that the 

 apical system is much more elevated, thus giving the test a more dis- 

 tinctly conical appearance ; ambulacral furrows are not present on the 

 under surface ; and the superior surface shows no interambnlacral de- 

 pressions. Its conical shape also distinguishes it from the other 

 San Pablo species. It differs from Astrodapsis tumidus, n. subsp. 

 cierboensis in its sub-pentagonal outline in contrast to the commonly 

 elliptical outline of the latter ; and from Scutella pabloensis, n. sp., in 

 its smaller size and greater thickness of test. 



Occurrence. — Upper San Pablo group in the same beds with Astro- 

 dapsis tumidus Remond and Ast>vdapsis tumidus (small thick form). 



Average measurements. — Anteroposterior diameter, 34.6 mm.; 

 transverse diameter. 31.5 mm.; greatest thickness, 10.6 mm. 



ASTRODAPSIS WHITNEYI Remond 

 Plate 40, figure 4 



Astrodapsis whitneyi Remond, Proe. Calif. Acad. Sci., vol. 3, p. 52, 1863- 

 1867. 



Astrodapsis whitneyi Remond. Gabb, Geol. Surv. Calif., Palaeontology, 



vol. 2, p. 37, pi. 13, figs. 67 and 67a, 1869. 

 Astrodapsis whitneyi Remond. Merriam, Proc. Calif. Acad. Sci., Ser. 3, 



Geology, vol. 1, no. 5, p. 167, pi. 21, fig. 4, 1899. 

 Astrodapsis whitneyi Rgmond. Arnold, Bull. U. S. Geol. Surv. no. 396, pi. 



11, fig. 1, 1909. 



Astrodapsis whitneyi Remond differs mainly from Astrodapsis 

 tumidus Remond in its much thinner margin; smaller tubercles; rela- 

 tively less pronounced widening of the ambulacral plates toward the 

 ambitus; flat interambnlacral areas; and in its characteristic bell- 

 shaped appearance. 



Occurrence. — Upper San Pablo group with Astrodapsis tumidus 

 Remond, and in the upper part of the Santa Margarita formation. 



