286 Systematic Paleontology 



Genus THAMNISCUS King 

 ThAMXISCUS KEGULAIilS n. sp.' 



Plate XLVII, Figs. 4-6 



Description. — In the striation of the reverse and the general aspect of 

 the obverse or celluliferous face of the branches this species resembles the 

 three New Scotland species from Xew York cited for comparison. How- 

 ever, the resemblances are of generic ratlier than of specific import. In 

 T. nysa and T. variolaia the growth of the zoarium, especially as regards 

 branching, is more rapid and more irregular, giving a bushy aspect rather 

 than the gracefully erect habit marking the Maryland species before us. 

 T. fruticeUa seems to be nearer than the other two New Scotland species, 

 but unfortunately only the reverse side of this species is known. So far 

 as the visible features permit forming an opinion T. regularis differs in 

 its less frequent and more regularly dichotomous branching, and less 

 crowded branches. 



On the obverse side the zocecial apertures are rounded, with j^eristome, 

 and arranged in fairly regular diagonal rows, four or five in each row. 

 Minute granules cover the peristomes and are arranged in regular series 

 over the depressed intervening spaces. Larger nodes occasionally inter- 

 spersed between the zocecial apertures. The reverse side is closely but 

 distinctly striated longitudinally in young examples and at the growing 

 ends of older specimens. Toward the basal part of the latter the striae 

 are obscured and finally obliterated by nearly smooth secondary deposit. 



Occurrence. — Helderberg Formatiox, Keyser Member. Devil's 

 Backbone. 



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



Family RHABDOMESONTIDAE 



Genus ORTHOPORA Hall 



Orthopora rhombifeka (Hall) ? 



Plate XLV, Figs. 12-14; Plate XLYIII, Fig. 6 ; Plate LI, Fig. IS 



Trematopora rhomiifera Hall, 1874, Twenty-sixth Ann. Rept. N. Y. State 

 Mus., p. 103. 



' Cf. Thamniscus ? nysa Hall, 1883, Rept. State Geol. N. Y. for 1882, pi. xxii, 

 figs. 31, 32, 47, 48. Also T. fruticella and T. variolata of the same author, work, 

 and plate, figs. 33-46. 



