370 University of California Publications in Geology [Vol. 8 



ASTRODAPSIS TUMIDUS Remond 

 Plate 39, figures 7a, 7b, 7c, and plate 40, figures la, lb, 2 



Astrodapsis tumklus Remond, Proc. Calif. Acad. Sei., vol. 3, p. 52, 1863- 

 1867. 



Astrodapsis tumidus Remond. Gabb, Geol. Surv. Calif., Palaeontology, vol. 



2, p. 37, pi. 13, figs. 68 and 68a, 1869. 

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



Geology, vol. 1, no. 5, pp. 166-167, pi. 21, fig. 3, 1899. 



The type specimens of Astrodapsis tumidus Remond are from 

 the lowest beds in which this species occurs, and is associated with 

 Astrodapsis ivhitneyi Remond. All the forms found in subsequent 

 strata show more or less variation from the type. Two of these 

 variations are cpuite distinct, but gradations can be found among them 

 all. A small, thick form (see pi. 40, figs, la, lb), occurs throughout 

 the Upper San Pablo group, but is more common in the lower part of 

 this division. A large form (see pi. 40, fig. 2), occurs in one horizon at 

 the top of the San Pablo group. This differs from the others in its 

 much larger size and more exaggerated specific characteristics. 



Astrodapsis tumidus Remond may be distinguished from Astro- 

 dapsis tumidus, n. subsp. cierboensis and Scutella pabloeusis, n. sp., by 

 its more strongly elevated and usually less closely constricted petals ; 

 narrower ambulacra and poriferous areas ; and marked interambulacral 

 depressions. Its margin is thinner than that of Astrodapsis t. cier- 

 boensis and thicker than that of Scutella pabloensis. From Astro- 

 dapsis alius, n. sp., it differs in its less distinctly conical test. 



Occurrence. — Upper San Pablo group. Both the typical Astro- 

 dapsis tumidus and its variations occur in the upper part of the 

 Santa Margarita formation. 



Average Measurements 



Typical form Small thick form Large form 



Anteroposterior diameter 36.5 mm. 27.8 53.9 



Transverse diameter 30.4 24.6 46.9 



Greatest thickness 8.8 8.6 15.1 



ASTRODAPSIS TUMIDUS, Remond, n. subsp. CIERBOENSIS 

 Plate 39, figures 5a, 5b 



Test subcireular to elliptical in outline; strongly depressed; margins 

 thickened and rounded ; some specimens slightly notched at the ambitus 

 in the posterior ambulacral areas. Apical system central and some- 

 what sunken. Summit anterior to apical system. Ambulacra petaloid ; 

 petals slightly elevated, broad, and wide open at their extremities. 



