98 PALEONTOLOGY OF OHIO. 



to about four times its diameter at the other point, and forming a flat- 

 tened bead-like body within each chamber. 



Surface of the shell apparently smooth, except that the edges of the 

 septa are raised above the general level, in the form of narrow rings. 

 This feature may possibly be due, in part at least, to an expansion of the 

 septa during the process of petrifaction, but it would scarcely seem to be 

 the case, as the feature is too regular, and only shows where the external 

 shell is wholly or partly preserved. The rings are often some little 

 wider on the surface than the thickness of the septa. Where the sur- 

 face is most perfectly preserved there is also a finely reticulate or net- 

 like character, dividing the surface into small rhombic figures of micros- 

 copic dimensions, having their longest diameters corresponding to the 

 length of the shell, and presenting a surface similar to that frequently 

 produced by the attachment of bryozoans ; but the regularity is so great 

 that this can not have been the origin of the feature ; neither have the 

 jhombs any thing like a radial structure or direction in any part, as 

 would have been the case if they were the result of the growth of a bry- 

 ozoan. Along one side of the shell and directly opposite to the position 

 of the siphuncle, there is a narrow, raised, longitudinaj line, extending 

 the entire length of the tube, but slightly interrupted just above each 

 ■one of the annular rings. 



The species resembles somewhat the O.crebriseptum, Hall (Palaeontology 

 • of New York, Vol. I., p. 313, pi. 87), but increases much more rapidly in 

 size, and does not possess the longitudinal markings of that species." In 

 the rapid expansion of the tube it corresponds nearly with 0. Sieboldi, 

 Bill., from the island of Anticosti ; but the septa are much more numer- 

 ous, that one having seventeen in the space of seven inches, while this 

 one has the same number in the space of two and a half inches. 



Formaiion and locality : In the shales of the Hudson River group, near Waynesville, 

 Ohio. The specific name is given in honor of Jesse Van Duser, Esq., of that place, 

 who furnished the specimen, and several others, described and figured, from the same 

 locality. 



Orthoceeas Carleyi (n. sp.). 



Plate 4, fig. 19. 



Afnong the fossils received for examination from the Hudson River 

 .'formation there is a very interesting specimen of Orthoceratite, which 

 ■does not appear to belong to any described species, but is in such a state 

 ■of preservation as to present but few distinguishing features. Still, the 



