366 / 'r'licn/iiujs of the O/ilo State .Iciidciiiy of Science. 



RHOMBOPORA ARVI\TA Ulrich. 



1SS4. Kliniiituil^ora (ininita. L'lricli, Jnur, Cinn. Sue. Xat. Hist., Vol, 

 \'l I , p. '■-<], pi. 1, ligs. ."), .ja. 

 Kaskaskia gmup: Tateville, Kentuck}-. 



Description. — Zoariuni slender, ramo.se, solid. Zoecia 

 with deep, narrow, rhomljic vestibules, arranged regularly in a 

 quincuncial manner, thus forming vertically, transversely, and 

 obliquely intersecting series. The obli(|ue series slightly more 

 evident. Apertures subcircular and comparatively large. The 

 peripheries of the vestilniles form rounded ridge-like thickenings, 



"F"iG. (!. — Rlioinbopora aniiata. Zoarium magnitierl twenty times to show 

 the apertures and spines. 



and at the intersections of the oblique ones of these are located 

 one or two prominent spines. 



Zoarium i mm. in diameter ; and with eleven to thirteen 

 zoecia to one circumference. 



This species can be readily recognized by its slender cylin- 

 drical zoarium with rhoml)ic vestibules and prominent spines. 



Horizon and locality. — ^laxville limestone. 

 Undetermined zone : Harper Shaft, Olive Furnace. 



CLASS BRACHIOPODA. 



DERBYA CRASSA— Meek and Harden. 



1853. Or//n\s- loidiracntuiit? Hall, Stansbury Explo. and SurAey Gt. Salt 

 Lake, p. 412, pi. 3, fig. G. 

 Carboniferous : Missouri River. 



