Description of Two New Genera and Eight New Species. 41 



This is a very distinct, well-marked species, readily distinguished 

 from all others by the coarseness of the radiating striae, and their 

 manner of division near the margin. 



The specimens were collected by Dr. S. S. Scoville, in whose honor 

 I have proposed the specific name, in the upper part of the Hudson 

 River Group, near Lebanon, in Warren county, Ohio. 



T^ENIASTER ELEGANS, n. Sp. 



Plate I., fig. 6, natural size, with ends of rays doubled under the specimen; fig. 6a, en- 

 larged view of the same specimen, approximately correct; fig. 6b, end of ray, natural size: 

 fig. 6c, enlarged view of same. 



This species is founded upon more than thirty specimens occurring 

 on a single slab, but showing only the ventral side, with the exception 

 of the ends of some of the rays. 



The body is deeply stellate, and the rays long, slender and flexible, 

 and margined on either side with a row of spines. 



From the length of some of the rays, a complete specimen, properly 

 spread, would probably have a diameter of an inch and a quarter, or 

 more. The rays taper to a sharp point, are rounded on the dorsal 

 side, and margined on the ventral side by a row of spines, one spine 

 arising from each plate. Only two rows of plates seem to form the 

 dorsal side of a ray. The ventral side of each ray is marked by a 

 furrow in the middle, separating two series of plates or ossicles. These 

 plates are a little longer in the direction of the ray than wide, and 

 alternately break joints at the middle, where they are slightly con- 

 tracted. 



This is a delicate species readily distinguished from those hitherto 

 described. It is the first species, in this genus, that has been found in 

 the Hudson River Group of this country, and the specimen is remark- 

 able for the number of individuals that are clustered together on a 

 small slab. 



The specimen is from the collection of I. H. Harris, Esq., of Waynes- 

 ville, and was found in the upper part of the Hudson River Group in 

 that vicinity. 



Stromatocerium richmondense, n. sp. 



Plate II., fig. 1. piece of a slab, polished and containing specimens, natural size; fig. %a, 

 central part of a specimen showing the ends of the vertical tubes, magnified more than 100 

 diameters; fig. 16. view of concentric laminae and longitudinal structure of tubes, magnified 

 more than 100 diameters. 



This is a small, globular or spheroidal sponge, consisting of numer- 

 ous, irregularly concentric, more or less wrinkled, calcareous laminae, 



