160 FIFTEENTH KEPOET ON THE CABINET OF NAT. HISTORY. 



/- 





PLATE 3. 



rig. 1, 2 & 3. Centronella impressa. ' t- ^ c' <<^ 



Fourteenth Report on the State Cabinet, p. 102. 



Fig. 4 & 5. Interior of dorsal and ventral valves of the same. 



Fig. 8 & 9. Cryptonella. Generic illustrations. 



See pages 101 & 102 of the Fourteenth Report on the State Cabinet. 



Fig. 6 & 7. Cryptonella eximia. An undescribed species from the 



Lower Helderberg limestone. The form is ovate, narrowing 



towards the beak, which is sometimes elongate, slightly curving 



but not incurved, perforate at the extremity, with the space 



below, between the perforation and the beak of the opposite 



, ^ ^^ valve, occupied by two deltidial pieces. Surface marked by 



^^; concentric striae and some stronger lines of growth. 



T!!^ '' '^ .; This species usually occurs in fragments or crushed : no specimens have, 



""> V until now, been found sufficiently entire for illustration. 



Fig. 10 & 11. Athyris angelica. Dorsal and ventral valves. 



Fourteenth Report on the State Cabinet, p. 99. 



Fig. 12 & 13. Front and profile views of the same. 



Fig. 24. Cast of ventral valve of the same. 



Fig. 15 & 16. Athyris cora. 



Thirteenth Report on the State Cabinet, p. 94. 



Fig. 17 - 19. Meristella nasuta =z Atrypa nasuta, Conrad. Fi- 

 gures showing gradations in size, and in the front extension. 



Fig. 20. Profile view of specimen fig. 19. 



Fig. 21 & 22. Dorsal and profile views of a large specimen, probably of 

 this species. The prolongation in front is wider and more ex- 



4 tended than in the ordinary forms. t. - ^r .,, / 



I 











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