64 THE CHICAGO ACADEMY OF SCIENCES. 
Of the above regions, the Canadian has produced the largest 
number of species (14). The Greenlandian region has but one peculiar 
species, and the West Indian, Carolinian and Alaskan regions have but 
two species peculiar to their areas. 
A study of the distribution maps reveals certain interesting facts 
regarding the present dispersal of North American Lymnezas. The 
largest number of species is found between the 38th and the 60th 
degrees of north latitude. North and south of these parallels the 
number of species notably decrease. 
TABLE SHOWING DISTRIBUTION IN LATITUDE. 
Species arid varietiessnorth vol GO ss o.i ge ee cae oe ee 13 
Species and varieties between 38° and 60°................. 85 
Specicsicand svanlenlesmsouicim Ome Serine leere rete nie eaeare 29 
Species and) vanleriesssouth cores Ome teen eeneniet 7 
Species: and yariettes south. wt 20" 42 42. ase ne aise ee eee 3 
It will be noted in the above table that the number of species first 
increases and then decreases, the number steadily falling until but three 
species are represented south of 20°. This table also indicates the 
northern distribution of the family, 85 species and varieties, or 85 per 
cent being found between 38° and 60° of north latitude. It is note- 
worthy that but three species of Lymnzeas have been recorded from 
the tropical zone. 
SPECIES AND VARIETIES NORTH OF 60°. 
stagnalis appressa. holbollii. vahliu arctica. 
stagnalis wasatchensis. obrussa. randolphi. 
truncatula. palustris. alaskensis. 
perpolita. vahlit. petersi. 
vahlit pingelli. 
SPECIES AND VARIETIES BETWEEN 38° AND 60°. 
stagnalis appressa. humilis rustica. traski. 
stagnalis perampla. ferruginea. vahlir. 
stagnalis lilliane. obrussa. vahlit arctica. 
stagnalis wasatchensis. obrussa peninsule. pallida. 
sanctemarie. obrussa exigua. catascopium. 
occidentalis. 
lepida. galbana. catascopium niagarensis. 
columella. petoskeyensis. davisi. 
columella chalybea. palustris. nasoni. 
columella casta. palustris alpenensis. qwoodruffi. 
utahensis. palustris blatchleyi. pseudopinguis. 
megasoma. palustris desidiosa. decollata. 
haldemani. neopalustris. sumassi. 
truncatula. elodes. jacksonensis. 
doddsi. elodes jolietensts. gabbi. 
bulimoides. elodes shurtlefi. emarginata. 
bulimoides cockerelli. 
obrussa decampi 
reflexa. 
catascopium adamist. 
emarginata mighelst. 
