62 



University of California Publications in Geology [Vol. 12 



SISMONDIA(?) COALINGAENSIS Twitehell 

 Plate 4, figures 3a, 3b 



Sismondia (?) coalingacnfiis Twitehell. U. S. Geol. Surv. Mon., vol. 54, 

 1915, p. 183, pi. 85, figs. 2a-2c. 



Holotype.~m. 165717 U. S. Nat. Mus. 



Since no specimens of this species have heen available for study 

 Twitehell 's description is given here verbatim : 



The test of this species is very small, rarely exceeding one-half an inch in 

 length. In marginal outline it is suboval to subovate, broader posteriorly than 

 anteriorly. The whole form much depressed, slightly tumid centrally; margin 

 rather thin. Apex subcentral or slightly eccentric posteriorly. Lower surface 

 concave. 



The ambulacral petals are subclliptical in outline, extending a little more 

 than half waj^ to the margin; the posterior pair shorter than the anterior pair; 

 pores round, pairs of pores conjugated. The whole test is covered with small 

 but conspicuous tubercles, scattered irregularly. 



The apical system is subcentral or slightly eccentric posteriorly, coincident 

 with the apex. The details could not be made out on the specimen studied. 



The peristome and ambulacral grooves could not be made out. The periproct 

 is small, inframarginal, almost marginal. 



Dimensions. — Length 12 millimeters; wi<lth 10 millimeters; height 2 milli- 

 meters. 



Related forms. — <S. coalingaensis resembles Sismondia (?) arnoldi and Scutella 

 (?) merriami. From the former it differs in having shorter, subelliptical petals 

 and from the latter in lacking the tumid petals and in having a more longi- 

 tudinally oval marginal outline. 



Geologic liorizon. — Etchegoin formation, Pliocene. 

 Locality. — Jacalitos Creek, half a mile east of Kreyenhagen's, 

 Coalinga district, California. 



Family SCUTELLIDAE Agassiz 

 Genus SCUTELLA Lamarck 



SCUTELLA ANDEESONI Twitehell 

 Plate 12, figures la, lb, Ic 



Scutella sp. a P. M. Anderson. Proc. Calif. Acad. Sci., ser. 3, Geol., vol. 2, 



1905, p. 193, pi. 13, fig. 8. 

 Scutella andersoni Twitehell. U. S. Geol. Surv. Mon., vol. 54, 1915, pp. 



183-184, pi. 85, figs. 3a-3d. 



Holotype. — No. 165719 U. S. Nat. Mus. ; figured specimens nos. 

 11363 and 11364 Univ. Calif. Coll. Invert. Pal. 



Test small. Measurements of specimen no. 11363 : antero-posterior 

 diameter 25.4 mm., transverse diameter 25.4 mm., greatest height 



