1920] 



Kew: Cretaceous and Cenozoic Echinoidea 



115 



From D. coalingaensis Twitehell it differs in having a more elevated 

 test, with the upper surface regulai'ly arched; a less eccentric apical 

 system ; in that the jieriproct is situated nearer the edge of the test ; 

 and in that the petals are always more or less tumid. 



Geologic horizon. — Upper Etchegoin formation, Middle Pliocene. 

 Associated with Dendrastcr perrini (Weaver). 



Localities. — Holotype from "south of Lucille well, two miles south- 

 west of Coalinga;" also occurs on Pajaro River one and a-half miles 

 southwest of Chittenden, near Sargent Oil Field, Santa Cruz County, 

 California, Univ. Calif, loc. 3129. 



DENDRASTER ASHLEYI (Arnold) 

 Plate 27, figures la, lb, Ic 



Echinaracliniiis aslilci/i Merriam (MS.), Ariiolil. U. S. Geol. Surv. Bull., 



no. 322, 1907, p. .58, pi. 24, figs. 6, 7. 

 Dendraster ashleyi. Stefanini, Boll. Soc. geol. ital., vol. 30, 1911, p. 706. 

 ScuteUa ashleyi. McLaughlin and Waring, Calif. State Min. Bur. Bull., 



no. 69, 1914, map folio, fig. 43. 



Holotype. — No. 165259 U. S. Nat. Mus. ; figured specimen no. 11043 

 Univ. Calif. Coll. Invert. Pal. 



Test of medium size. Measurements of specimen no. 11043 : antero- 

 posterior diameter 62.5 mm., transverse diameter 74 mm., greatest 

 height 6 mm. Markedly- thin. Marginal outline sulKjuadrate, the 

 posterior margin being broadly truncated ; transverse diameter the 

 greater, with its greatest width in the posterior portion of the test. 

 Upper surface rises gently to the summit, which is posterior to the 

 center of the test and in front of the apical system; greatest elevation 

 within the radius of the length of the petals. Apical system situated 

 far back near the posterior margin. Madreporite pentagonal in out- 

 line, with four genital pores opposite the four anterior corners. Lat- 

 eral petals not symmetrical, the anterior rows of pores in each petal 

 being curved to a greater degree than those of the posterior rows. 

 Petals of the bivium relatively short, and diverging so as to fomi with 

 their axes an angle of nearly 180 degrees. Poriferous areas compara- 

 tively wide, each being about one-half the width of the interporiferous 

 area. Petals of the trivium of the same length ; lateral ones somewhat 

 narrower than the odd anterior one. Poriferous areas of tlie anterior 

 lateral petals equal to about one-half to one-third the width of the inter- 



