148 University of California Ftiblications in Geology [Vol. 12 



for their entire length. Posterior, pair of petals bent slightly back- 

 ward. Pores elongate and conjugate. Odd anterior petal differs 

 from the others in that both rows of pores extend in parallel lines 

 nearly to the ambitus ; pores more nearly round than in the others. 

 All petals situated in rather deep sulci, the odd anterior one contin- 

 uing to the moutli on the under surface and forming a broad notch 

 in the ambitus. Peristome sunken and placed close to the anterior 

 margin, small in size, and transversely suboval in outline. Posterior 

 labrum present. Actinal surface nearly flat, with a slight tendency 

 to form a broad keel. Periproct small, round, and situated high up 

 on the posterior truncation of the test. Tuberculation not shown. 



Related forms. — Among west coast spatangids this form most 

 closely resembles Hctniaster calif ornicus Clark. H. oregonensis differs 

 in that the apical system is not so eccentric, the posterior pair of 

 petals are more divergent, and the odd interambulacral ridge is not 

 so well developed and acute. 



Geologic h orizo n . — Cretaceous. 



Locality. — Cotypes from near Old Dollarhide tollgate on Pacific 

 Highway, Jackson Countj^, Oregon, Univ. Calif, loc. 3142. 



Genus SCHIZASTER Agassiz 



SCHIZASTER CALIFOENICUS (Weaver) 

 Plate 41, figure 4 



Linihia {?) calif orntca Weaver. Univ. Calif. Publ. Bull. Dept. Geol., vol. 



5, 1908, pp. 273-274, pi. 21, fig. 2. 

 Brisftopsis californica. Stefanini, Boll. Soc. geol. ital., vol. 30, 1911, p. 705. 

 Linthia ? californica. Clark and Twitehell, U. S. Geol. Surv. Mon., vol. 



54, 1915, pp. 214-215, pi. 98, fig. 4. 



Holotype. — A badly crushed specimen no. 11349 Univ. Calif. Coll. 

 Invert. Pal.; ncotype, no. 11259 Univ. Calif. Coll. Invert. Pal. 



Size of test large. Measurements of specimen no. 11259 : antero- 

 posterior diameter 43 mm., transverse diameter 32 mm., greatest 

 height approximately 10 mm. Ambital outline subcircular, somewhat 

 undulating, with a broad notch at the distal end of the anterior 

 sulcus; an indistinct notch is present in the odd posterior inter- 

 ambulacral area. Upper surface considerably elevated; interambu- 

 lacral areas highly ridged, between which are deep, broad ambii- 



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