122 
PALEONTOLOGY OF NEW YORK. 
form and acute apex that it could not have been tubular, and, besides, there is 
no evidence of a perforation in the plate. 
The spirals have the same structure as in Eu- 
METRiA, and Derby has shown that the posterior 
margins of the coils are fimbriated. The loop, also, 
is quite similar to that of Eumetria Vermuiliana. 
Waagen has represented it in Eumetria (Hustedia) 
grandicosta, Davidson, as terminating in a short, i^oov oi HustedilMoHm, uavcou. (c.) 
sharp, retrally directed stem, but in the American specimens this stem appears 
to be much longer and the posterior edges of the lamellm both of the stem and 
the lateral branches are furnished with divergent spinules. In all our prepara¬ 
tions the extremity of the stem appears to be simple. 
The exterior of the shell is coarsely plicated and the structure strongly 
punctate. 
The representation of this genus of shells in American faunas is restricted, 
so far as known, to the species H. Mormoni*, which occurs in the upper Car¬ 
boniferous of Missouri and Kansas, and has been identified by Derby in the 
Coal Measures both of Brazil and Peru, The two species described by Waagen 
from the Salt-Range of India as Eumetria grandicosta, Davidson, and E. indica, 
Waagen, belong to Hustedia, and probably also Retzia (Terehratula) radialis, 
Phillips, Retzia carhonaria, Davidson, and R. {Terehratula) ulothrix, de Koninck^ 
from the British Coal Measures. Retzia ulothrix, R. radialis, R. Davidsoni, R. in¬ 
termedia, de Koninck, occur in equivalent faunasin Belgium.f 
It is probably true that the various species from the St. Cassian beds, which 
have been referred by Bittner | to the genus Retzia, have their closest 
relations with Hustedia. These are, for the most part, coarsely ribbed forms, 
some of them with extravagantly high areas. Their internal structure has 
not been satisfactorily demonstrated. 
* Whether the other American Carboniferous species, iJeizia comprma, Meek; R. IFoosto'i, White; 
R. Meekana, Shumard, and R. papillata, Shumard, are congeneric with H. Mormoni, is not yet determined, 
t See Davidso>% Carboniferous Brachiopoda, pp. 87, 88, 219, pi. xvii, figs. 19-21; pi. xviii, figs. 14, 15; 
pi. 1, figs. 3, 4-9; and db Koninck, Faune du Calcaire Carbonifere de la Belgique ; Brachiopodes, Explic., 
pi. xxii, figs. 1-4, 10-19. 
I Brachiopoden der alpinen Trias, 1890. 
