EXPLANATION OF PLATE 23. 

 All figures natural size. 



Pig. 1. Scutella fairbariksi Arnold. Vaqueros formation, lower Mio- 

 cene; Ventura County (?). 



Fig. 2. Scutaster andersoni, n. gen. and sp. Upper surface of only 

 known specimen. Miocene, one mile northeast of Muir, Contra Costa County. 



Fig. 3. Scutella ( ?) norrisi, n. sp. Inferior surface of weathered spec- 

 imen showing outline of test. Vaqueros formation, lower Miocene: five 

 miles northwest of Stone Canon coal mine, Monterey County. 



Fig. 4. Spatangus (?) pachecoensis, n. sp. Upper surface of fragment 

 of large specimen, showing form of interambulaeral plates. Tejon forma- 

 tion, Eocene, one and one-half miles northwest of Pacheco, Contra Costa 

 County. 



Fig. 5. Spatangus (?) pachecoensis, n. sp. Cast of test. Same locality 

 as fig. 4. 



