Maryland Geological Survey 221 



interspace ; lines of tubes arranged in reticulated form, with unequal in- 

 terspaces. Tubes within, septate transversely and striated longitudinally, 

 externally transversely striated, and sometimes with more elevated ridges 

 at equal intervals. This coral is so well known by its peculiar net-like 

 structure, that a description seems scarcely necessary. It presents con- 

 siderable variety, however, in the mode of its reticulation and tlie size of 

 the spaces. The openings of the tubes upon the surface are oval, though 

 often varying in size, and the whole expansion is frequently very thin and 

 slender, and in other cases thick and strong. The greater number of 

 specimens found in New York are siliceous, the interior structure is 

 not well preserved; and the transverse septa seen only at irregular in- 

 tervals. The striae noticed in the interior of the tube are distinct crenu- 

 lated ridges like the bases of lamellae, and give to the well preserved tubes 

 a very characteristic feature." Hall, 1852. 



Diameter of tubes about 2 mm. 



Occurrence. — IIelderberg Formation, Keyser Member. Devil's 

 Backbone, Cash Valley, Pinto, Eawlings. 



Collection. — Maryland Geological Survey. 



Class HYDROZOA 



Subclass STROMATOPOROIDEA 

 Section MILLIPOROIDAE 



Family STROMATOPORIDAE 



Genus STROMATOPORA Goldfuss 



Stromatopora constellata Hall 



Plate XXVII, Figs. 1-6 ; Plate XXVIII, Figs. 1-2 ; Plate XXIX ; 



Plate XXX, Fig. 1 



Stromatopora constellata Hall, 1852, Pal. N. Y., vol. 11, p. 324, pi. Ixxii, figs. 



2a, b. 

 Stromatopora concentrica Hall, 1852, Pal. N. Y., vol. ii, pi. Ixxiii, figs. 2, 2a, 2b. 

 Cwnostroma constellatum Spencer, 1882, Bull. Univ. State of Missouri, vol. i, 



No. 1, p. 48, pi. vi, fig. ii. 

 Stromatopora constellata Whiteaves, 1896, Can. Rec. Sci., vol. vii, p. 137. 



