1920] 



Kew: Cretaceous and Cenozoic Echinoidea 



149 



laeral sulci ; odd anterior sulcus nearly twice the width of the lateral 

 ones. Apical system posteriorly eccentric, small, and sunken to the 

 same level with the petals ; four large genital i)ores present. Petals 

 unequal in length ; those of the bivium shorter than the anterior lateral 

 pair, but of the same width. Inner rows of more or less rounded 

 pores extend in approximately parallel lines to the end of the petal ; 

 outer rows of elongate pores diverge at first and then converge within 

 the distal half, nearly closing with the inner rows at the end of the 

 petal. Interporiferous area markedly narrow ; equal to about one- 

 half the width of each poriferous area. Odd anterior petal obliter- 

 ated on the specimens at hand. Inferior surface flattened. Peris- 

 tome relatively large, transversely elongate, situated well toward the 

 anterior portion of the test, sunken, and with a prominent posterior 

 labrum. 



Related forms. — This species may be readily distinguished from 

 other California schizasters by its long posterior petals, \ery broad 

 petals, and by its depressed test. 



Geologic horizon. — Agasoma gravidum zone, San Lorenzo series, 

 Oligoeene. 



Localities. — Holotype from west side of Bear Creek, Contra Costa 

 County, California ; figured specimen from same horizon Univ. Calif, 

 loc. 3055. 



SCHTZASTEE CORDIFORMIS Kew, n. sp. 



Plate 42, figures Irt, lb, Ic, Id . 



Holotype. —^0. 11388 Univ. Calif. Coll. Invert. Pal. 



Test small, usually smaller than that of ScJiizaster lecontei Mer- 

 riam. Measurements of specimen 11388: anteroposterior diameter 

 24 mm., transverse diameter 24.3 mm., greatest height 14.7 mm. Out- 

 line from above cordiform, with posterior end slightly truncated. 

 Apical system small and slightly eccentric anteriorly ; summit behind 

 the apical system and about midway to the posterior margin on the 

 prominent ridge which extends from the apical system to the peri- 

 proct. Upper surface depressed and sloping rather steeply from the 

 apex to the anterior margin, so that the cross-section of the test is 

 semicircular in outline. Ambulacra petaloid. Petals of the bivium 

 subelliptical in shape and comparatively narrow; anterolateral petals 

 of the same width and about twice as long as the posterior pair. Petals 

 imperfectly preserved so that the details can not be made out clearly. 



