Raymond : Gastropoda of the Chazy Formation. 215 



Family Xenophorid^e Deshayes. 

 Genus Clisospira Billings. 



Clisospira bassleri sp. nov. 



(Plate LIV, figures 16, 17.) 

 Dr. Ray S. Bassler of the United States National Museum has 

 brought to my attention a small specimen of a species of Clisospira 

 from the collection of Chazy fossils in the National Museum. These 

 fossils were collected on Isle La Motte, Vermont, and associated with 

 the Clisospira were numerous specimens of Raphistoma stamineum, 

 Scenella montrealensis and Bucania sidcatina. 



Description. 



Shell small, sinistrally coiled, expanding gradually. Apical angle 

 70 . Volutions 3^, plump, convex, the last one extending all around, 

 making a large, nearly circular aperture. The shell covers all but the 

 initial whorl, and is thin, smooth, without surface markings. Suture 

 rather deeply impressed. The cast of the initial volution shows that 

 the young shell was loosely coiled, almost in one plane. 



This shell is very similar to the two shells described as Clisospira 

 curiosa by Billings and to the Clisospira orientalis Whitfield from the 

 Trenton of Wisconsin. From the original specimen of Clisospira 

 cur-iosa Billings, our specimen differs in the less expanded aperture, 

 the smaller size and the greater number of whorls. From the second 

 specimen described by Billings under the same specific name, Clisospira 

 bassleri differs in lacking the reticulated surface markings. From 

 Clisospira occidentalis our species differs in the absence of the indis- 

 tinct undulations found on that species, the sharper apical angle, and 

 in possessing one more whorl. The holotype is 9 mm. in diameter at 

 the aperture and 7.5 mm. high. 



This species differs only slightly from two of the species previously 

 described, yet there are differences, and they should be pointed out. 

 The writer believes that more harm may be done by uniting unlike 

 forms than by a too fine discrimination between closely related ones. 

 The fossils found in the Chazy are usually poorly preserved, and in 

 studying them, it has been the policy of the writer to give new names 

 whenever it was not possible to prove identity with species already 

 described. 



Locality. — A rare species in the Chazy on Isle La Motte, Vermont. 

 The holotype is in the United States National Museum. 



