THE KIMMSWICK AND PLATTIN LIMESTONES 
197 
tiate it from the Anticostian Richmond species with which this 
form usually is identified. Specimen preserved at Harvard 
University. 
Mcewanella nov. gen. 
Hehertella Uneolata was described by Savage (Illinois Academy of 
Science, 1917, p. 267, pi. I, figs. 1, 2) from the Fernvale member 
of the Richmond near Thebes, Illinois, and at Cape Girardeau, 
Missouri. The same species was described by Eula Davis Mc- 
Ewan as Platystrophia fernvalensis (Proc. U. S. Nat. Mus., 56, 
1919, p. 428, pi. 50, figs. 1, 2, 3), from the Fernvale limestone at 
the old quarry southeast of Regenhardt’s quarry, northwest of 
Cape Girardeau, Missouri. This species begins at the beak as 
a distinctly plicated shell, the plications being distinctly striated 
longitudinally. Toward the anterior margin the plications be- 
come indistinct but the longitudinal striations remain distinct. 
The median part of the brachial valve is elevated into a fold, and 
the corresponding part of the pedicel valve is* depressed into a 
sinus. 
The anomalous position of this species is indicated by its ref- 
erence to Hehertella by one author, and to Platystrophia by a 
second. By the present writer it is regarded as distinct from 
both, the sharply defined radial striations being unknown in 
typical Platystrophia, and the distinct plications of the earlier 
stages of growth being unknown in Hehertella. The pedicel valves 
of both Hehertella and Platystrophia have deep muscular impres- 
sions, those of Platystrophia being deeper and narrower. In this 
respect the species here under consideration resembles Platy- 
strophia more closely. 
Owing to the occurrence in the Kimmswick limestone of south- 
eastern Missouri of a second species, closely resembling Heher- 
tella Uneolata generically, the desirability of a separate generic 
designation for species having this type of structure was increased. 
Therefore, the name Mcewanella is proposed in honor of Miss 
McEwan, the author of the recent detailed study of the genus 
Platystrophia, cited above. 
