PLATE LIX. 



Sctjtella mississippiensis Twitchell, n. sp. (p. 124). 



U. S. Nat. Mus. 137655, specimen A, type. 



Figure la. Upper surface of the test, 

 lb. Lower surface of the test, 

 lc. Posterior surface of the test. 

 Id. Lateral surface of the test, 

 le. Apical system, X 6. 

 If. Part of the ambulacra, X 8. 



Sctjtella mississippiensis Twitchell, n. sp. (p. 124). 

 U. S. Nat. Mus. 137655a, specimen B. 



Figure 2. Upper surface of the test. 

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