38 James E. Conkin, Barbara M. Conkin, William T. Mason, Jr. 



Systematic Paleontology 



Anguispira alternata (Say) 

 PI. 2, figs. 6a, 6b. 



Description. Specimens fit the specific description of Anguispira alternata as 

 given by Pilsbry ( 1948, p. 569 ) ; first one and one-half nuclear whorls smooth to 

 faintly granulated; remaining whorls with moderately strong striations; periphery 

 broadly angular. Specimens are weathered with color pattern showing only faintly. 



Measurements. Measurements of Anguispira alternata are given in Table 1. 



Distribution. Canada (Ontario to Nova Scotia); in the United States mainly 

 east of the Plains (Pilsbry, 1948, p. 569). 



Ecology. "Anguispira alternata is found under loose bark, dead wood, and in 

 stone piles. Several observers have found it climbing trees .... Anguispira al- 

 ternata is a plastic snail, varying from angular and heavily ribbed forms, in rocky 

 or mountainous country, to rounded and finely or weakly striate shells in the low- 

 lands .... A high-spired form is assumed in many places west to Kansas .... 

 [apparently] owing to the moist air of such places which permits the snails to live 

 both day and night out from under logs where the narrow quarters tend to keep 

 the shell growth flattened" (Pilsbry, 1948, pp. 570-573). 



Remarks. Pilsbry (1948, p. 569) reported Anguispira alternata to range from 

 the Aftonian to the Recent in the Mississippi Valley; however, in the classic Kan- 

 sas Pleistocene sequence it is known from only the post-Bradyan Bignell loess 

 (Frye and Leonard, 1952, pp. 176, 182), The species has been reported from the 

 loess at Natchez and Vicksburg by Shimek (1902), Richards (1938); in addition, 

 Conkin and Conkin (1961, pp. 13-15) reported A. alternata from the loess at 

 Vicksburg, Mississippi and have presented evidence for a post-Bradyan age for 

 the upper 30 feet of the loess at Vicksburg. Browne and McDonald ( 1960 ) re- 

 corded A. alternata from the Tazewell deposits of Jefferson County, Kentucky. 



Table 1. Measurements of Anguispira alternata in mm. 



Specimen 



Section 



and bed 



nos. 



Length 



Max. 



diam. 



Min. 

 diam. 



Apert. 

 height 



Apert. 

 width 



No. of 



whorls 



9, PI. 2, figs. 6a, 6b .. 



10 



11 



.. 2,5 



2,5 

 2,5 



10.0 

 11.0 

 10.0 



17.9 

 18.0 

 16.2 



16.0 

 16.2 

 15.0 



7.5 

 8.2 

 7.0 



7.2 

 8.1 



7.5 



5i/ 2 

 5i/ 2 

 5i/ 2 



Armigerus obstructus (Morelet) 

 PI. 2, figs, la, lb. 



Description. Shell, small; planispirally depressed; body whorl thickened be- 

 hind the aperture; aperture fully rounded. Shell is white and it is strongly 

 weathered. 



Measurements. Measurements for Armigerus obstructus are given in Table 2. 



Distribution. The genus is living in Bee County today (personal communica- 

 tion from Dr. J. P. E. Morrison). 



Ecology. "Planorbulids are pulmonates, but rather well adapted to aquatic 

 life in quiet waters" (Leonard, 1950, p. 17). 



Remarks. Specific determination was made by Dr. J. P. E. Morrison. Only 

 one fragmentary specimen was found in the samples. This is apparently the first 

 report of the species from the fossil record. 



