PLATE IV. 



Cidakis californicus Clark (p. 30). 



U. S. Nat. Mus. 30184, type. 

 Figure la. Spine, 

 lb. Same, 

 lc. Articular surface of lb, X 2. 



Cidakis taylorensis Clark (p. 30). 



U. S. Nat. Mus. 30183, type. 



Figure 2a. Fragment containing two contiguous interambulacral plates of the same series. 

 2b. Spine. 



Cidakis plumasensis Clark, n. sp. (p. 31). 



U. S. Nat. Mus. 31191, type. 

 Figure 3. Portion of interambulacral area. 



Hemicidaris intumescens Clark (p. 31). 



U. S. Nat. Mus. 30187 and 30188, types. 



Figure 4a. Upper surface of the test. Partly restored. 

 4b. Lower surface of the test. Partly restored. 

 4c. Lateral view of the same. Partly restored. 

 4d. Two interambulacral plates, X 5. 

 4e. Lower portion of interambulacrum, X 5. 

 4f. Upper portion of the same, X 5. 

 4g. Portion of ambulacrum, X 4. 

 4h. Tubercle from above, X 8. 

 4i. Lateral view of the same, X 8. 



