ATLANTIC STATES. 107 
Helix hortensis (imported), coast of New England and banks of St. Lawrence. 
»  pulchella (smooth var. only), Boston, Ohio, Missouri. 
Helicella cellaria (glaphyra, Say ?), N. E. and middle States. 
» pura, nitida, and fulva? 
Zua lubrica, North West Territory. 
Succinea amphibia (= campestris, Say ?). 
Limax agrestis (= tunicatus, G.), Mass. 
», flavus, New York, introduced. 
Vitrina pellucida (= Americana ?) Limnea palustris (= elodes, Say ?), 
Arion hortensis, New York (Dekay.) os truncatula (= desidiosa?). 
Aplexa bypnorum (= elongata, Say ?). 
Auricula deticulata, Mont., New York Harbour. 
Alasmodon margaritiferus (= arcuatus, Barnes). 
Anodon cygneus (= fluviatilis, Lea ?). 
The shells proper to Canada, or derived from the adjoining 
States, are only 6 sp. of Helix, 2 Succineas, and 1 Pupa; 8 sp. 
of Cyclas have been obtained from the region of Lake Superior. 
The following species occur in New England :— 
LE WGIUBS petecoscedaadenua ode 13 1 21h EE secbbedeganosdeoobeos 2 LOB tO het ecconccccdanaédons 5 
SHUICCINCBmcecicscssseeses 2 JIE FTOHONS “epodacqoosan00 11 Alasmodon ........000. 2 
ADB acescecsescssertvsews 7 IPaludintae cess sscecceses it AmOdonyrescecesecsena 2 
EATING Bivovsivves etic vss 'e 7 Wiallvatas icetsweestenastene 2 Cyclase sonscnceumenseeecs 6 
ATIC VIUSis ss cccusescataess 2 PAUITI GU] meee seeseeaeses 1 PISIGuUNA eee ee ereects 1 
Carychium exiguum, Say, is found in Vermont, and Limnea 
(Acella) gracilis in Lake Champlain; Valvata tricarinata and 
Paludina decisa are characteristic forms. 
The genera Clausilia and Cyclostoma are entirely wanting in 
Canada and the Northern States. The Zimacide are represented 
by Philomycus, of which there are 9 reputed species, ranging 
from Massachusetts to Kentucky and South Carolina. 
17. ATLANTIC STATES. 
The parallel of 36° N. lat. forms the boundary-line of two 
botanical regions in the United States; but the evidence of the 
fresh-water shells, in which they are particularly rich, seems 
to fayour a division into two hydrographical provinces—the 
region of the Atlantic streams and the basin of the Mississippi. 
About 50 fresh-water Pulmonifera, 150 pectinibranchiata, and 
250 bivalves, are reputed to be found in the States, and it is 
supposed that only a few species are common to both sides of 
the Alleghanies. Cyclas mirabilis, Pisidiwm Virginicum, Cyrena 
3,000 feet on the mountains of Scotland. (Watson.) According to Pallas it abounds 
on the western flanks of the Ural Mountains, but disappears on their eastern side, an@ 
is not found in Siberia, In the Pliocene period it appears to have spread itself north 
ward and westward to Iceland, Greenland, and Newfoundland, where it still grows, 
the only heath indigenous to the New World, (Humboldt.) 
