5TAURASTRUM. 1 '27 



Frequent in ponds, ditches and the like. 



Some authors unite these forms with the preceding species ; 

 others hold them as distinct for the reason that the rays often 

 have transverse series of large granules, which give a cren- 

 ulate appearance to the margins. Our artist tailed to bring 

 out this feature a> distinctly a> it should be. 



St. muricatum, Breb. Plate XLII, tigs. ;'>-fi. 



Suborbicular, deeply constrictedj sinus narrow linear, or 

 slightly enlarged outwardly; rough with somewhat conical 

 granules : semicells subsemiorbicular, angles obtusely rounded. 

 or truncate ; end view triangular, sides convex, angles rounded 

 or truncate spinous. 

 Diameter Hi 15 n. 



Pools and ditches, in many distantly separated localities, 

 but not very numerous. 



St. asperum, Breb. Plate XIJI. figs. 7. 8. 



In comparison with the preceding (St. muricatwm), gran- 

 ules are emarginate, or divided; semicells broadly elliptic; 

 sinus much wider, and sides in end view straight ; otherwise 



very near it. 



Habitat and >i/.e the same. 



St. rugulosum, Breb. Plate X1J, figs. H, 42. 



Semicells elliptic, denticulate at their sides ; end view tri- 

 angular, with angle- broadly rounded and sides slightly con- 

 cave or straight. 



Diameter about 38 ft. 



Very nearly related to the preceding; I quote the diagnosis 

 of the author. Bailey reports it from New York and Rhode 

 Island ; I add it from Pennsylvania and New Jersey. Not a 

 rare form. 



St. punctulatum, Breb. Plato XL1, tigs. 43-45. 



Cytioderm punctate-granulate, semicells elliptic, straight, 

 ends broadly rounded ; end view triangular, angles not pro- 

 duced, broadly rounded, sides lightly refuse. 



Diameter 30-35 ft. 



Frequent in marsh pools, ditches, dripping rocks and the 

 like. 



