﻿1 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



Unfortunately these cannot be illustrated at this time. As the species 

 is distinct from .1/. mammulata and marks a different stratigraphic 

 horizon, the above new name is proposed for its future designation. 



.1/. epidermata is readily distinguished from M. mammulata, with 

 which it has generally been identified by collectors, by differences 

 in their respective methods of growth. Both are massive species, 

 but the Richmond form grows into large flat or irregularly hemi- 

 spherical masses, sometimes as much as 300 mm. in width and 150 

 mm. in height, and always, in the hundreds of specimens seen by us, 

 having a more or less flattened though strongly undulated epithe- 

 cated base. M. mammulata never attains such large proportions, and 

 its masses are irregularly lobate or more or less rounded, instead of 

 depressed hemispheric. Another distinction lies in the mesopores, 

 which are more numerous in M. epidermata. The following descrip- 

 tion sums up the characters of this new species. 



Zoarium of broad, thick, lamellate expansions or masses, some- 

 times reaching the dimensions mentioned above. Base always lined 

 with an epitheca and more or less flattened and concentrically wrin- 

 kled. Surface with rather closely arranged maculae which sometimes 

 form sharp tubercles and again rounded monticules. Zocecia small, 

 rather thin-walled, angular where mesopores are less common and 

 rounded where they are abundant; 10 to 11 zocecia in 2 mm. 



In tangential sections the zocecial walls exhibit the usual granulose 

 structure characteristic of the genus. Acanthopores small, rather 

 inconspicuous, appearing more like granules. The mesopores are 

 small, 2 or 3 usually to each zocecium. Vertical sections show the 

 mesopores tabulated with straight diaphragms one-half to one tube- 

 diameter apart. Cystiphragms line the zocecial tubes in both re- 

 gions and are accompanied by a corresponding number of 

 diaphragms. 



Occurrence. — Abundant in the nodular argillaceous limestones, of 



Middle Richmond age, exposed along Whitewater river at Richmond, 



Indiana. Occurs also wherever these strata are exposed at other 



localities in Indiana and Ohio, good specimens being found at 



•rd, Ohio, particularly. 



Cat. Xos. 43.172, 43,173, U. S. N. M. 



Genus Orbignyella new genus 



Monticulipora (pars) Ulrich, Jour. Cincinnati Soc. Nat. Hist., v, 1882, 

 pp. 153, 232. — Geol. Surv. Illinois, vm, 1890, pp. 370, 407. 



I he recent close study of all the species of Monticulipora has 

 shown that, despite previous restrictions, the genus still includes 



