PLATE XVI. 



Leptarbacia argtjtus Clark, n. sp. (p. 53). 

 Johns Hopkins Univ. T 3004, type. 



Figure la. Upper surface of the test, 

 lb. Lateral surface of the test, 

 lc. Apical system, X 8. 

 Id. Portion of ambulacrum, X 8. 

 le. Portion of ambulacrum, X 15. 

 If. Portion of interambulacrum, X 4. 



Orthopsis planttlata Clark, n. sp. (p. 54). 

 Johns Hopkins Univ. 73005, type. 



Figure 2a. Upper and lower surfaces of two forms. 

 2b. Lateral surface of the test. 

 2c. Portion of ambulacrum, X 6. 

 39800°— 15 18 



