180 THE CHICAGO ACADEMY OF SCIENCES. 
Washingtonand Chicago. It is the largest species of the genus 
found in the United States, and may be known by its flat form, 
very transverse aperture, deep umbilicus and indented umbili- 
cal region. It has been found somewhat plentifully in the 
greenhouses at Lincoln Park, Chicago, but is particularly large 
and fine in the greenhouses at Washington Park, where it is 
found beneath old boards under the flower pot shelves. Speci- 
mens have been found here measuring over half an inch in di- 
ameter. It has not been found outside of the greenhouses.* 
Fic. 36. 
Comparative figures of VITREA and ZONITOIDES. (After Morse, 
Amer. Nat., Vol. 1, Nos. 8 and 10.) Enlarged. 1, ZONITOIDES ARBOREUS 
Say; 2, VITREA HAMMONIS Strém; 3, VITREA INDENTATA Say; 4, ZON- 
ITOIDES MINUSCULUS Binney. 
67. Vitrea Hammonis Strom, pl. xxviii, fig. 10. 
flelix hammonis STROM, Act. Nedross., Vol. III, p. 435, pl. vi., fig. 16, 
1795. 
Helix radiatula ALDER, Cat. North and Durh., p. 12, No. 50, 1848. 
Flelix viridula MENKE, Syn. Méth., ed. 2, p. 127. 
Flelix striatula GRAY, non Linné, nec Miller; undescribed. 
Flelix nitidosa FERUSSAC; undescribed. 
FHlelix electrina GOULD, Inv. Mass., p. 188, fig. 111, 1841. 
Flelix pura PFEIFFER, Binney, non Alder. 
flelix viridula PFEIFFER, ex parte, 1848,'‘non 1881; Binney apud Pfeif- 
fer, non Menke. 
flelix hammonis \WESTERLUND, Morch, Pfeiffer, 1881. 
Hyatina pellucida LEHNERT, Science Record, June, 1884, p. 141. 
Shell: Small, depressed, thin, umbilicated; surface shining, 
the lines of growth well marked, impressed, more or less equi- 
*Mr. W. W. Calkins has reported the finding of Zonites alliarius Miller in Chicago 
greenhouses, but thus far the record has not been substantiated. All of the specimens 
have been draparnaldi. 
{From Dall, Proc. U.S. Nat. Mus., 1885, p. 269. 
