1914] Kew: Tertiary Echinoids of the Carrizo Creek Region 



49 



central and slightly sunken. Anus large and inframarginal. Internal 

 structure made up of concentric rows of slender pi Hers near the edge 

 of the test. 



This species may be distinguished from the Recent Clypeaster 

 rotuntlus A. Agassiz, of the Gulf of California, by its more pentagonal 

 shape and its thinner margin. In Clypeaster cleserti the odd anterior 

 petal is the longest, and is slightly open, the remainder being of the 

 same length. The longest petals in Clypeaster rotunelus are the 

 bivium and these are somewhat open. 



Occurrence. — Lower Division of the Carrizo formation at Coyote 

 Mountain and Carrizo Valley. University of California Localities 

 737, 739, 2064. 



Measurements 





No. 10046 



No. 10056 



No. 10057 



No. 1005 



Anteroposterior diameter 



65.1 mm. 



112. 



70.1 



74.0 



Transverse diameter 



57.0 



108.5 



68.2 





Greatest thickness (center) 



8.0 



14.5 



115. 



8.7 



Greatest thickness (marginal) .. 



.. 3.0 



9.0 



6.0 



5.5 



CLYPEASTER CAERIZOENSIS, n. sp. 

 Plate 2, figures 2 and 2a 



Outline pentagonal to suboval, with slight notch opposite the 

 interambulacral areas. Test depressed, thick, and edge slightly swollen. 

 Apical system central, elevated but little. Petals tumid and wide open 

 at the ends, extending over one-half the distance to the margin. Inter- 

 poriferous spaces slightly raised, but pores sunken, especially the outer 

 row, the inner row being situated on the slope of the raised area of 

 the petal. Pores conjugate. Actinal surface deeply sunken to the 

 peristome. Ambulacral furrows broad, deep and extending undivided 

 to the edge of the test. Anus inframarginal. Tubercles small and of 

 the same size on both actinal and abaetinal surfaces. 



This species is not related to any living form in the Gulf of Cali- 

 fornia. It resembles to a slight extent Scutella gabbi Conrad from 

 the San Pablo formation of Middle California. The shape of Cly- 

 peaster carrizoensis is more pentagonal, the edges of the test thicker, 

 and the apical system more central than in Scutella gabbi. 



Occurrence. — Lower Division of the Carrizo formation at the foot 

 of Coyote Mountain. University of California Locality 738. 



Measurements. — Maximum anteroposterior diameter, 24 mm. ; 

 maximum transverse diameter, 21 mm. ; maximum height, 7 mm. 



