﻿$6 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



Occurrence. — Abundant in the Richmond formation at Hanover, 

 Ohio. 

 Cat. No. 43,202, U. S. N. M. 



STIGMATELLA NANA new species 

 (Plate X, 7-10; Plate XIV, 11, 12) 



This species has mesopores and is related in other respects to the 

 Richmond form, S. inter porosa. It may be distinguished, however, 

 by its more numerous acanthopores and less numerous mesopores, 

 and by other, less important, differences. The zoarium of S. nana 

 is small and irregularly branched. The surface is often hirsute 

 because of the acanthopores which, although quite numerous, are 

 small. In S. inter porosa the zoarium, although also of small size, 

 consists of frequently dividing and more regularly formed branches, 

 ( >n which the acanthopores are seldom observable. The tabulation of 

 the zocecia and mesopores is much alike in the two species, the only 

 difference noted being that diaphragms occur more frequently in the 

 zocecial tubes of 6". interporosa. 



Occurrence. — Very abundant in the Utica formation at West Cov- 

 ington, Kentucky, and other localities in the vicinity of Cincinnati. 

 Ohio. The exact horizon is about 25 feet above the top of the 

 Trenton. 



Cat. No. 43,203, U. S. N. Ah 



STIGMATELLA NICKLESI new species 

 (Plate X, 1-3; Plate XIV, 9, 10) 



This species is related to S. clams (Ulrich) and resembles that 

 form in its zoarial characteristic, but the unusually large acantho- 

 pores will distinguish it at once. In S. nieklesi the acanthopores 

 are generally situated only in the junction angles of the zocecia and 

 are less numerous than in 5". clavis. The numerous acanthopores of 

 the latter species (see plate x, 4) inflect the walls, giving the peta- 

 loid appearance characteristic of several species of the genus. In 

 S. nieklesi this inflection has not been observed, the walls being 

 thin and straight, and the large acanthopores confined to the angles. 

 The two species are further distinguished by their methods of 

 growth, 6\ clavis forming neat, tightly adhering, club-shaped zoaria 

 about crinoid columns, while S. nieklesi loosely covers similar objects. 



The specific name is in honor of Mr. John M. Nickles, of the 

 U. S. Geological Survey, who discovered the species in considerable 

 numbers and recognized its distinctness. 



