G2 THE CHICAGO ACADEMY OF SCIENCES. 



Species 

Rio Grandian 
Lower Mississippian 
Carolinian 
Nova Scotian 
Central American 
West Indian 
Greenlandian 
Labradorian 
Hudsonian 
Mackenzian 
Yukonian 
Alaskan 
Californian 
Asia 
Canadian 
xUpper Mississippian _ 
WUANTATE LST) cicyevcer sane: seh are 
POM OMANI © ca lohareies siete 
198 SanOuelllls 66 a0 won Sc 
Va sesleneteuelecobe tates: eveneee 
NYOMI ise hrveven te evets re | 
ELAS ao ce eae * | * poe Fa | 
Valliiwe cee: * «| *) #| | * 
Walarctica seca se) *) ® | Fae elie | | 
Vol Dilieelitinetce teeta se “ ~ 
neopalustris ....... - 
Pali ees. ncnevocsnecersve 
GCawesermoyonuhen sao ooge 
Gy Nias arenisisi meee. 
Ce AC ANUS Wa ctaciee sree ou 
CEE Sosoco ogoae ud | 
* Coloradoan 
** Columbian 
* Great Basin 


* 
* 
** eH 
ex ee 


déecollata Syscsee be 
SUMASST oS biaseeeeee ac = ¥ | 
JAGMSOMENSIS eee ck * 
Sa bon eicterereee = 
emer cmatan sss eee * | | * 
eo PIMISMelSi onan * | |= 
Se aes Ul atainis oom oan * | +4 
e. wisconsinensis.... bi 
e. canadensis........ * 
e; ‘ontaniensisis...e- * 
CONETACtAN <.).ca,c01e slekets * | 
DUS DIsvieinlaieeris cence * 
Montana jt cttekcroe pes tae | 
OLOMENSIS! onsen * ies 
[opbolin(e nivale Soper ee nteendiet ae 63g 
DUCHY | Gas catelscare - 
a SOU A) ee den ieid chee aye ve 
Ihimilslleyil 42's ace cee 
DLEDUSIH ceiaeiaraketere nee SH te 
HamGdolipl: Sey ccescres || S|) SS 
alaskensis: 2oce6a0% ibaa 
DETECrSH, Sale eieeseee ~ 
BULIGAENISIS “leases s iene: * 
| fd) ey et tt |) 
otal Sind Xcwstens: 3| 1/50/16] 8|11| 5|22]16| 9|19| 9/36, 9 4124] 3] 3] 3 
The above total reveals certain interesting facts. The Canadian 
region is the best represented, containing 50 species and varieties, or 
nearly one-half of the total fauna. The Upper Mississippian region 
is next in representation, 36 species and varieties being known. The 
Columbian (22), the Nova Scotian (24), the Californian (19) and 
the Hudsonian (16) regions also contain a high percentage of species. 
The poorly populated areas are the Carolinian (4), Central American 
(3), West Indian (3), Greenlandian (3) and the Labradorian (1) 
regions. Only three species are common to America and Asia. 
The country surrounding the Great Lakes is at present the center 
of distribution of this family, 55 species and varieties living in this 
area, or more than half of the known species. Several species are 






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