24:2 THE CHICAGO ACADEMY OF SCIENCES. 



"SHELL : Ovate, conic, turreted, umbilicate, light yellowish horn- 

 colored, shining; lines of growth fine, irregular, subobsolete on the 

 body whorl, stronger on the apical whorls, reticulated by indistinct 

 revolving, impressed spiral lines. Spire elongated, apex subacute; 

 whorls 5, very convex, those of the spire somewhat shouldered, suture 

 deeply impressed; body whorl large, inflated, very convex. Aperture 

 broad, oval, subcircular, rounded above and below. Columella broadly 

 reflected over the round, deep umbilicus, convex, smooth with no fold, 

 parietal wall with a thin transparent callus. Lip sharp, but thickened 

 within by a heavy white callus." 



Length. Breadth. Aperture length. Breadth. 

 7.50 3.25 .... .... Type (Walker) 



7.75 4.25 3.80 2.50 Cotype 



TYPES: Collection Bryant Walker, three specimens, No. 13599. 

 TYPE LOCALITY: Indian Creek, Kent County, Michigan. 

 ANIMAL, JAW, RADULA and GENITALIA: Unknown. 

 RANGE: Michigan to New York. A species of the Canadian 

 region and of the Transition life zone. 



RECORDS. 



MICHIGAN: Indian Creek, Kent Co., Alma, Gratiot Co. (Walker). 



NEW YORK: Ellicott Creek, Williamsville, Erie Co. (Miss. Walker). 



GEOLOGICAL RANGE: Unknown. 



ECOLOGY : Not recorded. 



REMARKS : Cyclostoma may be known by its peculiar cyclostomoid 

 aperture and very obese body whorl. It combines characteristics of 

 both umbilicata and parva and has been derived, doubtless, from the 

 same stock. It approaches closer to parva in its rounded whorls and 

 acute spire. It strongly resembles certain forms from Des Moines, 

 Iowa (pi. XXIX, figs. 5-7), differing in the form of the aperture, 

 the body whorl and the inner lip, as well as in sculpture. 



"This very distinct little species was first collected by Dr. R. J. 

 Kirkland, of Grand Rapids, Michigan, and was listed as L. cubensis 

 Pfr. (umbilicata C. B. Ads.) in my Review of the Moll. Fauna of 

 Michigan (1894). Through the courtesy of Mr. E. A. Burt, curator 

 of the Museum of Middlebury College, I have been able to examine 

 the specimens of L. umbilicata deposited in that museum by Adams. 

 The two species are so obviously distinct that verbal comparison is 

 hardly necessary. L. cyclostoma differs in its more elevated, turreted 

 spire, more broadly reflected columella and thickened white lip. It 

 resembles umbilicata, however, in the sculpture, and is no doubt de- 

 rived from the same stock." Cyclostoma will probably be found in 

 many collections, labeled humilis or parva. 



