198 Systematic Paleontology 



The position of the genus has been much discussed. Steinmann re- 

 garded it as a form of Favosites. Eauff determined its true character, 

 showing that it is a sponge and regarded it as one of the siliceous sponges. 



Diameter of spheres, 25 mm. or at times a little greater. They are fre- 

 quently somewhat distorted by compression. 



Occurrence. — Heldekberg Formation, Keysee Member. In Tentac- 

 ulite subzone at Keyser, West Virginia; Cash Valley, Maryland. ;N'ew 

 Scotland Member. 21st Bridge ; Cherry Eun, West Virginia. 



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



Subbranch CNIDARIA 

 Class ANTHOZOA^ 



Subclass TETRACOROLLA 



Family ZAPHRENTIDAE 



Genus STREPTELASMA Hall 



Streptelasma strictum Hall 

 Plate XVII, Figs. 5-9 



Streptelasma (Petraria) striata Hall, 1874, 26th Rept. N. Y. State Mus. Nat. 



Hist, p. 114. 

 Streptelasma striata Hall, 1879, 32d Rept. N. Y. State Mus. Nat. Hist, p. 142. 

 Streptelasma strictum Hall, 1887, Pal. N. Y., vol. vi, p. 1, pi. i, figs. 1-10. 

 Streptelasma strictum Girty, 1895, 48th Ann. Rept. N. Y. State Mus., 1894, 

 vol. ii. p. 300. 



Description. — " Corallum simple, conical, very gradually and regularly 

 enlarging; straight or very slightly curved, except at the apex, which is 

 sometimes more abruptly bent. Exterior marked with strong undulations 

 of growth and numerous fine concentric striae; external rays very promi- 

 nent, from forty-five to fifty at a point where the diameter of the corallum 

 is 15 mm. ; the increase in number taking place usually at three distinct 

 points, but sometimes at only two. 



^ The study of the Lower Devonian corals of Maryland is based on material 

 which in some species was not well preserved or was inadequate in amount to 

 secure assured results in organisms of such difficulty. C. K. S. 



