Suburban Geology of Richmond, Indiana. 291 



lighter colored than the interior of the rock over which they are 

 spread. Specimens of this fossil are not readily found, as they 

 are comparatively rare. Fig. 4, represents one of the species, 



Fig. 5. 



and it is the only specimen I have met with. Fig. 5, is reduced 

 from the original to one-fourth the size. A transverse section of 

 this fossil would exhibit a quadrangular form. Fig. 6, is of the 

 natural size.* The fucoid portrayed in fig. 7, I have always 

 found in pale colored masses, seldom larger than that represented 

 in the cut, and they have almost invariably granular fragments 

 of other fossils adhering to them. 



Fig. 6. 



I have raised the question respecting the vegetable origin of 

 these fossils, in consequence of having discovered in several spe- 

 cimens of cord-like ridges, like fig. 5, a structure resembling that 



* Figs. 5 and 6 are probably the same fossil ; fig. 6 being a group of simple mem- 

 bers, each like fig. 5 having the same simple parallelisms and bifurcations. — Eds. 



