^Ew Species of Paleozoic Fossils. 181 



DESCRIPTION OF NEW SPECIES OF FOSSILS 



THOU THB 



VICINITY OF LOUISVILLE, KENTUCKY, AND THE FALLS OF THE 



OHIO. 



By James Hall and R. P. Whitpield. 



During the investigations for the fourth volume of the Palaeon- 

 tology of ]S'ew York, Dr. Knapp, of Louisville, Kentucky, kindly 

 loaned many specimens for study and comparison. The value of the 

 volume has on this account been much enhanced, and the author has 

 endeavored to give due credit therefor. At the request of Dr. 

 Knapp the new species now in my hands, belonging to his collection, 

 are described in the following pages. Comparisons of known ITew 

 York species, with specimens of the same species from this collection, 

 have been made during the studies for the Palaeontology of ]S"ew 

 York, and the results are given in the accompanying list. J. H. 



SilTirian Species. 



DiCTTONEMA PERGKACILIS n. Sp, 



Frond irregularly spreading, composed of very fine, closely 

 arranged meshes. Longitudinal filaments tortuous, not exceeding 

 a fiftieth of an inch in width, and the spaces between about equal. 

 Transverse filaments much narrower than the others, their distance 

 equal to twice or thrice that of the longitudinal ones, giving to the 

 openings an elongate hexagonal form. Serrations of the margins not 

 observed. Surface of filaments minutely wrinkled. 



This species is perhaps as nearl}^ related to D. gracilis of the 

 Niagara formation of New York, as to any known form, but it is 

 much more finely reticulated, and the reticulations are more regular in 

 their mode of growth than in that species. 



Formation and locality. In the Niagara limestone, near Louisville, 

 Ky. Cabinet of Dr. James Knapp. 



Orthis nisis n. sp. ^^ 

 Shell depressed-pyramidal, when resting on the dorsal valve. Dor- 

 sal valve semi-elliptical, flat or slightly concave in the middle, and 



