198 Annals of the Carnegie Museum. 



inner whorls, while it differs from Tetranota obsoleta in having the 

 slit band of the cast flat instead of distinctly grooved. 



Locality. — In the lowest beds of the Maclurites division of .the 

 Chazy on Valcour Island, New York. The figured specimen is in 

 the Carnegie Museum. 



Family Cyrtolitid;E Ulrich and Scofield. 



Genus Trigyra genus nov. 



Trigyra ulrichi sp. nov. 



(Plate L, figure 6.) 



Trigyra genus nov. Cyrtolitidae with two strongly developed 

 medio-lateral carinas on the body whorl. Type, Trigyra ulrichi sp. 

 nov. 



This genus is founded to receive a single species, and is based on a 

 small testiferous specimen in the National Museum. 



Description. 



Shell small, closely coiled in one plane, umbilici rather narrow. 

 Whorls angular at the boundaries of the umbilici, the back of the 

 whorl broadly and gently convex. The body whorl is marked by 

 five sharp revolving keels, two at the boundaries of the umbilici, two 

 in the middle of the back of the whorl, placed about half way between 

 the sharp V-shaped central keel and the keels at the umbilici. Ac- 

 cording to Dr. Ulrich, who has recently removed the shell from the 

 matrix, the two medio-lateral keels are not developed on the inner 

 whorls. 



The surface markings consist of fine lines of growth which sweep 

 gently back from the edges of the umbilici to the central keel. 

 Beside these markings the surface is covered with fine wrinkles trans- 

 verse to the lines of growth, and minute pits, producing the surface 

 characteristic of the Cyrtolitidae. This shell has somewhat the general 

 appearance of a Tetranota, but differs in its reticulate surface, V-shaped 

 central keel which does not carry a slit band, and in having an odd, 

 rather than an even, number of keels. 



Locality. — From the Chazy Limestone on Isle La Motte, Vermont. 

 The holotype is in the United States National Museum. 



