Maryland Geological Survey 211 



Diameter of corallum 100 mm. in large specimens, but usually smaller. 



A small variety with unusually small eorallites is found associated with 

 the usual form at some places. It does not ai)pear to differ in other 

 respects. 



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

 Backbone in Stromatopora beds; Cash Valley in Stromatopora beds; 

 Pinto in coral beds; 1^ mile southeast of Yerkes Mill, Flintstone, Mary- 

 land; near Seymour; in coral bed Keyser, West Virginia; Hyndman, 

 Pennsylvania, in Upper Stromatopora beds. The smaller variety occurs 

 in Stromatopora beds at Devil's Backbone; at Cash Valley, Maryland; 

 Keyser, West Virginia. 



Collection. — ]\Iai7]and Geological Survey. 



Favosites py'riformis Hall 



Plate XXIII, Figs. 1-4 



Asterocerum pyriforme Hall, 1852, Pal. N. Y., vol. ii, p. 123, pi. 34a, figs. la-e. 

 Favosites pyriforme Weller, 1903, Pal. N. J., vol. ii, p. 220, pi. xvii, figs. 3-5. 



Description. — Corallum pyriform to subhemispherical, consisting of 

 closely united prismatic eorallites. Epitheca not observed. Corallites 

 very unequal in size, 1 to 2 mm. diameter. Walls thin, bearing 12 or more 

 longitudinal rows of well-developed squamules in interior of tubes. 

 Tabulae close, usually less than diameter of tubes apart. Mural pores in 

 several rows. 



Corallum attaining a diameter of over 1 foot, usually much smaller. 



The shape of this coral is quite variable, usually pyrifonn when small, 

 subhemispherical when large, quite irregular when ve:y large. It closely 

 resembles F. helderhergice but differs in its thinner walls and rows of 

 squaiinihr. It also seems to be confined to a loAver horizon in Maryland 

 where it lias been observed only in the lower beds of the Keyser member. 



Occurrence. — Helderberg Form.vtion, Keyser Member. Cookerly, 

 below Stromatopora bed associated with Cladopora rectilineata ; Perdew's 

 farm north end of Martin ^lountain ; Williams Eoad \\ miles east of Push 

 at base of Keyser member; Hillside 4-100 feet X. 10° east of Signal Sta- 

 tion on Warrior ^lountain at base of Keyser member. 



Collection. — Marvland Geological Survev. 



