280 Systematic Paleontology 



of acanthopores. The diaphragms occur at infrequent and irregular in- 

 tervals in the zooecial tubes, the space intervening between successive 

 diaphragms varying from one to four or five tube diameters; in the meso- 

 pores they recur at much more frequent and regular intervals, averaging 

 about 6 in 1 mm. 



This common and rather striking species seems to possess all the essen- 

 tial characters of Stromatotrypa, which was founded upon a single species 

 from the Black Eiver and Trenton formations of Minnesota. Since that 

 time, five other Ordovician species have been determined by the writers 

 and await opportunity for publication. The species here described is 

 rather closely related to a lamellate new species occurring in the Sevier 

 shales of East Tennessee, but its globular mode of growth distinguishes it 

 from not only this, but all the other species. As far as known, there is 

 no associated form with which it can be confounded. 



Occurrence. — Helderberg Formation, Keyser Member. Iveyser, 

 West Virginia ; Cash Valley, Pinto, and other localities near Cumberland, 

 Maryland. 



Collections. — Maryland Geological Survey, U. S. jSTational Museum. 



Order CRYPTOSTOMATA 



Family FENESTELLIDAE 



Genus FENESTELLA Lonsdale 



Fexestella cumberlandica n. sp. 



Plate XLVII, Figs. 1, 2 



Description. — Among the collections from the Keyser limestone are 

 specimens of a species of Fenestella agreeing in general shape and size of 

 fenestrules with F. pkilia Hall ' of the New Scotland beds of New York, 

 but differing (1) in the more knotty aspect of the reverse side of its 

 branches, and (2) in the larger number of zooecial openings in a given 

 space. In Hall's figures of F. 2>li'ili<^, the zooecial apertures are repre- 

 sented quite regularly spaced with an average of three in the length of a 



* Rept. State Geol. N. Y. for 1882, pL xx, figs. 9-11. 



