4t>8 GEOLOGY OF OHIO. 



are very prominent From one to three similar pores, although sometimes of 

 smaller size, occupy the surface of each dissepiment. Non-poriferous surface not 

 observed. 



This species is somewhat similar to S. biserialis Swallow (Trans. St. 

 Louis Acad. Sci., vol. i, p. 179)., as identified and figured by Mr. F. B. 

 Meek (Final Rept. of U. S. Geol. Surv. Neb., pi. 7, fig. 5), but differs in 

 wanting the longitudinal nodose ridge between the pores of the dissepi- 

 ments, and in having only a single row of pores on those parts occupy- 

 ing the middle of the dissepiment as well as in the more slender, finer, 

 and more direct, and much more crowded rays, also in having a larger 

 number of somewhat smaller pores on the rays. Mr. Meek., loc. cit., iden- 

 tifies the above species with Synocladix Cestriensis {Septipora Cestriensis 

 Prout. Trans. St. Louis Acad. Sci., vol. i, p. 448, pi. 18, fig. 2), which differs 

 from the Ohio specimens in the stronger and thicker, as well as more fiexu- 

 ose rays; in the rounded fenestrules, and smaller-sized pores, which are also 

 more abundant, often showing three ranges on parts below bifurcations. 

 On direct comparison of the Newtonville specimens with specimens from 

 Chester, 111., these differences, especially those pertaining to the mode 

 of growth, are very marked and characteristic. 



Formation and Locality — In the Maxville limestone (Chester), at New- 

 tonville, Ohio. Collected by Prof. E. B. Andrews. 



BRACHIOPODA. 



Genus STREPTORHYNCHUS King. 



StreptorJiynchus crassum . 



Plate IX, figs. 11 and 12. 



Hemipronites crassum M. and W. 



Orthis Lasellcnsis McChesney, New Pal. Foss., 1859, p. 32, pi. i, fig. 6. 



Shell very variable in size and form, but usually more or less plano-convex as 

 seen in profile, somewhat semi-oval in outline, but usually a little too long from 

 beak to base to be strictly so considered. Ventral valve more or less flattened, a lit- 

 tle prominent on the umbo, but usual!}- becoming slightly concave toward the front 

 of the shell; cardinal area of moderate height with a covered deltidium ; beak more 

 or less distorted. Dorsal valve convex, often quite rotund, but usually depressed 

 convex, with a slightly prominent umbo. Surface of the shell marked by radiating 

 striae of considerable strength, which are sometimes sharply elevated and uniform, 

 but on other specimens may be distinctly alternating in strength or arranged in fas- 

 cicles ; these are crossed by fine concentric striae which give a finely crenulated sur- 

 face when viewed through a lens. Coarser concentric undulations of growth also 

 mark the shell at irregular distances. 



The individuals referred to this species are so extremely variable in 

 all their characters that it becomes next to impossible to properly charac- 

 terize the species \>y any kind of verbal description. There are, how' 

 ever, two distinct types of shell included among them, which possess 

 characters sufficiently distinct to indicate. One of these is strongly pla- 

 no-convex in profile, the dorsal valve being very highly convex, Avith a 



