FLATK LXUXIlI-Contlnued. 



Genus TREMATOSPIRA, Hall. 



r«ge \u. 



Trematospira Tennesseensis, sp. uov. 



Pigs 31-SS. I>oraal, profile and ventral views of the shell ; showing the convexity of the valves and the 

 eokrae plication. 



Lower Helderberg group. Perry oounty, Tennessee. 



ScBOBNUS HOiMCEOSPIRA, s.-gen. nov. 



Page 112. 

 See PlaW .50. 



HOM(EOSPIRA APRINIFORMIS, Hall. 



FTgB. 34. 38. Dorsal and profile views ; showing the contour and character of plication. 

 Niagara group. Ciiinberlarid, Maryland. 



Genus EUMETRIA, Hall. 



Page 116. 



See Plate 51. 



Eumetria Verneuiliana, Hall. 



Pigs. 36, 37. Dorsal and profile views of a large, sharply costate individual. 

 St. Louis limestone. Spergen Hill, Indiana. 



Genus PTYCHOSPIRA, gen. nov. 



Page 112. 



See Plate ."iO. 



Ptychospira sex-plicata, White and Whitfield. 



Fig. 88. The exterior of a pedicle-valve of the type specimen. 

 Kinderhook group. Burlington, Lnoa. 



Genus ZYGOSPIRA, Hall. 



Page IM. 



Se« Plate 54. 



Zygospira PUTILLA, sp. IIOV. 



Pigs. 39, 30. Dorsal and ventral views of a typical example. 



Hudson River group. IHke county, Missouri. 



Genus RHYNCHOTREMA, Hall. 



Page 1»2. 

 See Plate ati. 



Rhynchotrema c^pax, Coiuiid. 



Kg. 81. Cardinal view of the pedicle-valve shown on plate 56, fig. 17 ; showing the excavation of the 

 pedicle-paasage and its opening through the substance of the shell. X 3. 

 Hudson Rivei- group. Iron Ridge, Wisconsin. 



Genus GLASSIA, Davidson. 



Page l.">2. 



Glassia Rominoeri, .sp. uov. 



Kig. 32. A preparation showing the inti-overted coils and the direction of the loop. X 3. 

 Figs. 33-35. Dorsal, profile and ventral views of a specimen, showing the smooth exterior and bilobe<l 

 anterior margins of the valves. X 2. 



Trenton limestone. In a drift boulder, near Aim Arbor, Michigan. 



