﻿34 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



pores in these thickened zones. The incrusting forms without meso- 

 pores may be confused with Leptotrypa, but the characteristics just 

 mentioned distinguish them from species of that genus. For the 

 same reason and also because of the absence of a second set of acan- 

 thopores, the ramose forms with mesopores are distinguished from 

 species of Dekayella. The periodic development of the acanthopores 

 and thickening of the walls separate the new genus from Dekayia 

 with which it agrees in the sparse development of diaphragms. So 

 far as known the genus is confined to the Cincinnatian rocks. Of de- 

 scribed forms it includes Leptotrypa clavis Ulrich from the Utica, 

 and Monticulipora (Monotrypa) dychei James (see plate x, fig. n), 

 and Leptotrypa irregularis Ulrich (see plate x, figs. 5, 6; plate xiv, 

 figs. 6-8) from the Lorraine. 



STIGMATELLA CRENULATA new species 

 (Plate IX, 1-4; Plate XIV, 1, 2) 



Zoarium composed of cylindrical, subcylindrical or compressed, 

 frequently dividing stems 10 mm. or more in diameter, arising from 

 a broad base and forming a clump probably seldom more than 50 mm. 

 high. Surface even, but in well preserved mature specimens spinulose 

 because of the many acanthopores. Maculae well marked, generally 

 composed of mesopores which make up the characteristic "spots" but 

 sometimes formed exclusively of zocecia larger than the ordinary. 

 Zocecial apertures small, about 9 in 2 mm. with their walls thin and 

 often beautifully inflected by the numerous small acanthopores. Mes- 

 opores present, variable in number but usually few and mostly 

 aggregated in the maculae. In the axial region the zocecial tubes 

 have thin, finely crenulated walls, and occasionally a diaphragm or 

 two. In the mature region the walls increase slightly in thickness, 

 mesopores and acanthopores develop, and thin diaphragms cross the 

 zocecial tubes and mesopores at varying though always compara- 

 tively remote intervals. 



Occurrence. — Very abundant in lower part of the Richmond for- 

 mation at Hanover, Butler county, Ohio. Less common at the same 

 horizon near Oxford, Waynesville, Clarksville, and other localities 

 in Ohio. 



Cat. Nos. 43,197-43,199, U. S. N. M. 



STIGMATELLA SPINOSA new species 



(Plate IX, 5-8) 



The method of growth in this species is similar to that obtaining in 

 6\ crenulata, but under a lens 5\ spinosa is distinguished at once by 



