DESCRIPTIONS OF SPECIES. 133 



Lopaiity. — Salt Mountain, 6 miles south of Jackson, Alabama. 



Geologic horizon. — Lowei' OllgocGne, from the Coral limestone overlying- the 

 Vicksburg- beds. 



Types — United States National Museum. 



This species is absolutely peculiar for the North American Tertiary 

 deposits; nothing- even resembling- it is known from either the continent or 

 the West Indian reg-ion. 



Family ASTIlA]SrG-ID.gE Verrill. 



Genus ASTRANGIA Milne-Edwards and Haime. 



The three following species have given me great trouble, and I am not 

 thoroughly satisfied with the treatment of them, but with the material at 

 hand it is the best possible. 



ASTRANGIA EXPANSA Sp. nov. 



PI. XIV, figs. 3 too. 

 1890. Astrangia n. sp. Vaiigban. Bull. U. S. Geol. Survey No. 142, p. 51. 



This species is based on four specimens, one from Jackson, Mississippi, 

 from the collection of T. H. Aldrich; and three from Montgomerj^, Louis- 

 iana, in the collection of the United States National Museum. Apparently 

 the best method of presenting the specific characters is to begin by describing 

 the simplest specimen, and to compare the others with it. This specimen, 

 of which the following- is a description, is represented by PI. XIV, figs. 

 3 to 3b; it is from the collection of Mr. Aldrich. 



Colony incrusting, the specimen is attached to a valve of Barhatia 

 cucuUoides (Conrad). The base is much expanded, producing a thin coating 

 of considerable extent on the shell. The new corallites arise from basal 

 expansions of the old, sometimes at the base of the old, sometimes at a 

 considerable distance away, but are not at all crowded. The figure shows 

 their arrangement with reference to one another. The surface of the 

 expanded base possesses striatious, radiating around the corallites. Cor- 

 allites slightly elevated — 2 mm. Their outer surface corroded, jjrevent- 

 ing the costal characters from being studied. Tlie central corallite of the 

 colony nearly circular in outline, with a diameter of 3 mm. The other 

 corallites more or less elliptical. External surfaces of the corallites obscurely 

 costate. The walls not very thick. Septa in three complete cycles with a 



