72 



University of California Publications in Geology [Vol. 12 



and the notching in the ambulacral areas is deeper. It resembles 

 Scutella fairbanksi Arnold, but differs in its smaller size and in that 

 the rows of pores of the petals converge more strongly in the distal 

 part. The ratio between the length of the petals and the distance 

 from the ai^ieal system to the ambitus is less in 8. fairbanksi than in 

 aS*. gabhi var. tenuis, but the ratio of the latter compared with the 

 same ratio in S. gabbi shows a close resemblance. 



S. gabbi 



S. gabbi var. tenuis S. fairbanksi 



Average length of odd anterior petal 



= .6905 .674 .5945 



Average distance from apical system to ambitus 



The ratio of the length of the petals of the bivium to the distance 

 from the apical system to the ambitus shows similar results. 



It may be separated from Scutella andersoni Twitchell by its less 

 strongly notched margin in the posterior ambulacral areas; by its 

 more nearly circular outline, and its thinner test. 



Geologic horizon. — Immediately above the basal beds in the San 

 Pablo group. Upper Miocene. 



Locality. — Ilolotype from San Pablo Bay district. Contra Costa 

 County, California. 



SCUTELLA MEREIAMI (F. M. Anderson) 

 Plate 12, figures 3a, 3&, 3c, M, 3c, if 



Astrodapsis merriami F. M. Anderson, Calif. Acad. Sci., ser. 3, vol. 2, 



1905, pp. 193-194, pi. 14, figs. 33, 34. 

 Scutella merriami. Arnold, U. S. Geol. Surv. Bull., no. 396, 1909, p. 18, 



pi. 6, fig. 4. 



Scutella merriami. Arnold and R. Anderson, U. S. Geol. Surv. Bull., no. 



398, 1910, pp. 85, 86, 87, pi. 38, fig. 4. 

 Scutella (?) merriami. Clark and Twitchell, U. S. Geol. Surv. Mon., vol. 



54, 1915, pp. 185-186, pi. 85, figs. 7a, 7b, 7c, 8a, 81). 

 Sisinondia merriami. Stefanini, Boll. Soc. geol. ital., vol. 30, 1911, p. 702. 



Cotypes. — Nos. 53 and 54 Calif. Acad. Sci. Coll. Pal. 



Test small. Measurements of specimen no. 53 : anteroposterior 

 diameter 22.8 mm., transverse diameter 22.7 mm., greatest height 

 3.2 mm. Subcircular in outline, and with upper surface greatly de- 

 pressed ; margin swollen, and usually broadly notched in the ambu- 

 lacral areas, the notching being more prominent in the two posterior 

 areas. Apical system anteriorly eccentric ; apex slightly anterior to 

 the apical system. Lateral petals wide, partially closed, the pores 



