THE NATURAL HISTORY SURVEY. 265 



expanded, the columella callus making a ridge which is re- 

 flected over the umbilical region; umbilicus open, deep. 



Length, 12.50; width, 8.00; aperture length, 8.50; width, 5.50 mill. 

 11.00; " 8.00; " " 8.00; " 5.00 " 



11.50; " 8.00; " " 8.00; " 4.75 " 



Animal, jaw, radula and genitalia notexamined. 



Distribution: Southern part of Lake Michigan. 



Geological distribution: Pleistocene. 



Habitat: Probably similar to catascopium and emarginata, 

 but inhabiting rather deep water. 



Remarks: This species has been a puzzle for several years 

 and has been referred to both decollata and catascopium* It 

 certainly is not any form of catascopium, and judging by the 

 figures in Binney, Haldeman and Tryon it is not decollata. 

 Specimens of the latter received from the Philadelphia Acad- 

 emy of Sciences are decidedly different, the spire being longer, 

 the number of whorls less and the shape of the aperture dif- 

 ferent. The principal characteristics of woodruffi are its very 

 short spire, rapidly increasing and swollen whorls, and its 

 roundly oval aperture with its broad shoulder at the upper part. 

 It looks not unlike a miniature Limnaa emarginata var. mighelsi, 

 Specimens sent to Mr. Bryant Walker were declared by him to 

 be distinct from anything he had seen. The present species 

 has been described as new, for the reason that in a lot of some 

 two hundred specimens no individuals have been found con- 

 necting it with any known form. It has been found at Miller's, 

 Ind. , and along the lake shore, in Chicago, by Mr. F. M. Wood- 

 ruff, to whom the species is dedicated. 



107. LimnEea desidiosa Say, pi. xxx, fig. 20; pi. xxxi, fig. 7. 



Limncea desidiosa SAY, Journ. Phil. Acad., Vol. II, p. 169, 1821. 

 Limncea modicella SAY, Journ. Phil. Acad., Vol. V, p. 122, 1825. 

 Limncea acuta LEA, Trans. Amer. Phil. Soc., Vol. V, p. 114, pi. xix, fig. 



81, 1837. 



Limncea Philadelphia LEA, Proc. Amer. Phil. Soc., Vol. II, p. 32, 1841. 

 Limncea plica LEA, Proc. Amer. Phil. Soc., Vol. II, p. 33, 1841. 

 Limncea rustica LEA, 1. c., p. 33, 1841. 

 Limncea planulata LEA, 1. c., p. 33, 1841. 

 Limncea jamesii LEA, Proc. Phil. Acad., p. 113, 1864. 

 Limncea desidiosa var. decampi, L. H. STRENG, The Nautilus, Vol. IX, 



p. 123, 1896. (Variety.) 



Shell: Subconic, pointed, oblong, rather thin, sometimes 



*ln the writer's paper on Limnaea before mentioned, pi. i, fig. 12, this form was referred 

 to variety pinguis Say. The receipt of a large number of specimens has demonstrated that 

 it is not that form. 



