139 



recurved, and, turning back, extends two-thirds of the dis- 

 tance to the beak of the dorsal valve ; and the crural pro- 

 cesses are farther from the base of the loop than is repre- 

 sented in the typical figures of Waldheimia, and are 

 opposite the extremity of the recurved loop. 



Fig. 24. Fig. 29. Fig. 26. 



The accompanying figures illustrate all that has been ob- 

 served in this species. 



Fig. 24. Dorsal side of specimen, showing the crural 

 processes directed downwards. 



Fig. 25. Ventral side of specimen, looking into the dor- 

 sal valve. 



Fig. 26. Profile view of same, the figures twice enlarged. 



In the Thirteenth Report on the State Cabinet, 1 I pro- 

 posed the Genus Meristella, to embrace certain species 

 before included under the Genus Merista, and which were 

 shown not to possess the peculiar shoe-lifter process, or 

 transverse septum, characteristic of the latter genus. I re- 

 marked as follows : " Restricting, therefore, the significa- 

 tion of the genus Merista to such forms as were originally 

 included by Prof. Suess under that name, it becomes ne- 

 cessary to designate those species of similar form, but with- 

 out the peculiar appendage of the ventral valve, by another 

 generic term ; and I would therefore suggest the name of 

 Meristella, proposed by me last year." 2 



1 Page 74, 1860. 



2 In the Twelfth Report on the State Cabinet, 1859, page 78, in referring 

 Atrypa naviformis of vol. n, Pal. N. Y. to Merista," I said : " This species, 



