EXPLANATION OF PLATES 



EXPLANATION OF PLATE 3 



Fig. 1. Cidaris tehamaensis W. B. Clark. Holotype, specimen 31195, U. S. 

 Nat. Mus. Shelton's Ranch, Tehama County, Calif. Knoxville formation, Lower 

 Cretaceous. Natural size. Photographed by U. S. Geological Survey. 



Fig. 2a. Cidaris martinezcnsis Kew, n. sp. Specimen 11400, Univ. Calif. Coll. 

 Invert. Pal. Upper surface of test. Swett's Ranch, Contra Costa County, Calif., 

 Univ. Calif, loc. 241. Martinez group, Lower Eocene. X 3. 



Fig. 2h. Cidaris mai'tinezensis Kew, n. sp. Same specimen. Lateral surface 

 of test. X 3. 



Fig. 2(1. Cidaris martinezensis Kew, n. sp. Same specimen. Lower surface of 

 test. X 3. 



Fig. 3. Cidaris merriami Arnold. Specimen 11401, Univ. Calif. Coll. Invert. 

 Pal. Lateral surface of spine. North side Mount Diablo, Contra Costa County, 

 Calif., Univ. Calif, loc. 1592. Martinez group. Lower Eocene. X 2. 



Fig. 4. Cidaris lorenzanus (Arnold). Holotype, specimen 1056 U. S. Nat. 

 Mus. ; in Leland Stanford Jr. Univ. Coll. Pal. Lateral surface of spine. X 2. 

 Bear Creek, Santa Cruz County, Calif., Stanford Univ. loc. 109. San Lorenzo 

 series. Upper Oligocene. 



Fig. 5. Tripnemtes (Hipponoe) caJifornicus (Kew). Holotype, specimen 

 10055, Univ. Calif. Coll. Invert. Pal. Lateral surface of test. Coyote Mountain, 

 Imperial County, Calif., Univ. Calif, loc. 2064. Lower division of the Carrizo 

 Creek beds. Pliocene. Natural size. 



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