EXPLANATION OF PLATES. 

 Plate 1. 



Fig. 1. Spirillina vivipara. X 100. a, side view; b, peripheral view. (After Brady.) 



2. Spirillina vivipara. X 100. (After Brady.) 



3. Spirillina vivipara, var. rever tens. X 250. (After Rhumbler.) 



4. Spirillina vivipara, var. revertens. X 250. (After Rhumbler.) 



5. Spirillina vivipara, var. revertens. X 100. (After Brady.) 



6. Spirillina vivipara, var. revertens. X 250. (After Rhumbler.) 



7. Spirillina tuberculata. X 50. (After Brady.) 



8. Spirillina tuberculata. X 50. (After Brady.) 



9. Spirillina tuberculata. X 50. (After Brady.) 



Plate 2. 



Fig. 1. Spirillina limbata. X 50. a, side view; b, peripheral view. (After Brady.) 



2. Spirillina limbata. X 60. a, side view; b, peripheral view. (After Brady.) 



3. Spirillina tuberculata. X 45. (After Brady.) 



4. Spirillina limbata, var. papillosa. X 100. a, from above; b, from below; c, 



from periphery. 



Plate 3. 



Fig. 1. Spirillina limbata, var. denticulata. X 100. a, from above; b, from below; 

 c, from periphery. (After Brady.) 



2. Spirillina limbata, var. denticulata. X 50. a, from above; 6, from below; 



c, from periphery. 



3. Spirillina insequalis. X 120. (After Brady.) 



Plate 4. 



Fig. 1. Spirillina guttata. X 65. a, from above; b, from below; c, from periphery. 



2. Spirillina operculoides . X 65. a, from above; 6, from below; c, from periph- 



ery. 



3. Spirillina-like operculrum. X 65. a, from above i b from below; c, from 



periphery. 



Plate 5. 



Fig. 1. Spirillina decorata. X 50. a, from above; &, from periphery. (After Brady.) 



2. Spirillina decorata. X 50. (After Brady.) 



3. Discorbis concinna. X 100. a, from above; 6, from below; c, from side. 



(After Brady.) 



4. Discorbis tabernacularis. X 100. a, from above; b, from below; r, from side. 



(After Brady.) 



5. Discorbis patelliformis . X 100. a, from above; 6, from below; c, from side. 



(After Brady.) 



Plate 6. 



Fig. 1. Discorbis isabelleana. X 75. a, from above; b, from below; c, from side. 



2. Discorbis subfilosa. X 75. a, from above; b, from below; c, from side. 



3. Discorbis pulvinulinoides. X 75. a, from above; ft, from below. 



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