276 



University of California Publications. [Geology 



SPATANGUS (?) PACHECOENSIS, n. sp. 

 PL 23, figs. 4 and 5. 



Test usually small, average diameter 25 mm. Fragments have 

 been found with a diameter of 48 mm. Outline sub-circular, 

 truncated and notched anteriorly. Test thick, upper surface 

 strongly arched from the margin. Lower surface flat, forming a 

 distinct angle with the upper surface at the margin. Apical 

 system small, eccentric anteriorly. Lateral and posterior petals 

 of almost equal length, reaching about three-fourths of the dis- 

 tance to the margin; slender, and closed at the ends; poriferous 

 zones very slightly sunken, forming two-thirds of the width of 

 the petal. Anterior petal in a broad and fairly deep groove, and 

 apparently reaching the margin ; pores few and set wide apart 

 in contrast to the lateral and posterior petals, where the pores 

 are numerous and conjugate. Interambulaeral plates broadly 

 V-shaped ; very slightly raised in the center to form two low 

 interambulaeral ridges. Ambulacral plates not widening rapidly 

 beyond the ends of the petals. 



Dimensions: Longitudinal diameter 23 mm. 



Occurrence : This species has been found at but one locality 

 northwest of Pacheco, Contra Costa County, in the Tejon. All 

 specimens yet found are poorly preserved, being casts or impres- 

 sions, and are badly crushed. 



In the lowest portion of the beds containing this species, 

 numerous specimens of Schizaster lecontei were found. The range 

 of this latter species is, therefore, not limited to the Martinez 

 as was at first thought, but runs well up into the Tejon. 



SCUT ELLA FAIRBANKSI Arnold. 

 PI. 23, fig. 1. 



Scutella fairbanlfii (Merriam, M. S.), Arnold, II. S. G. S. Bull. 

 309, pi. 29, fig. 9. 



Test sub-circular in outline, much depressed; edges markedly 

 thin. Upper surface regularly arched from the margin, apex 

 central. Apical system small, and central ; petals extend one- 

 half to two-thirds the distance to the margin. Lateral and pos- 

 terior petals symmetrical, slender, almost closed at the ends, both 

 inner and outer rows of pores converging gradually for the last 



