120 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY 
feet. Here are listed many of those species which have been com- 
monly considered as belonfj;inp; to the Transition Zone. They are, 
the author contends, rcstiicted boreal species confined to "special 
habitats." It seems likely from their present homes that they are, 
as has been said, relics of an earlier fauna. An interesting parallel 
example is found in the Diptera where the species Billacomorphella 
jonesi Johnson was first described from an elevation of 3000 feet in 
North Carolina, and afterwards was found to be a boreal species 
extending northward to Machias, Orono, and Mt. Desert, Me. 
One of the misleading results of recognizing a Transition Zone is 
that truly boreal species are thus inadvertently placed in the 
Austral, because the Transition Zone of Merriam is but a sub- 
division of it, though many more odonate (3-1) typical boreal 
species, than austral, overlap into it. If included in either region 
it is far more logical to consider it a part of the Boreal. Even 
Scudder's intermediate boundaiy is too far north for an approxi- 
mate division between boreal and austral species. Of course aU 
boundaries are purely arbitrary, and those recognized are the 
result of a purely arbitrary selection. Dr. Merriam said, in fact, 
and his words have been frequently overlooked: "The zone as a 
whole is characterized by comparatively few distinctive animals 
and plants, but rather by the occurrence together of southern 
species which here find their northern limit, and northern species 
which here find their southern limit." In other words it is not a 
zone at all, but simply as he calls it, an "overlap" area. The fol- 
lowing species are of the boreal type to which he refers, and in- 
habit for the most part cold streams of wooded country. 
17. Agrion aequabile, eastern, spring. Its varieties make the species' range 
transcontinental. Outside New England and south of Canada where it 
has been taken in Nova Scotia, Quebec, and Ontario, it has been taken in 
New York at Axton (2,000 ft.), Keeseville (2,000 ft.), and at Bronx Park 
and Long Island at sea level; in New Jersey at Newfoundland (770 ft.) 
and Great Notch (411 ft.); in central Ohio (744 ft., Lat. 40° N.); in cen- 
tral and northern Indiana (750 ft., Lat. 39.5°-41.5° N.); Waterloo 
(841 ft.), Iowa; Milwaukee Co. (600 ft.), at Divide (1,500 ft.), and in 
Washington Co. (900 ft.), Wisconsin; and in Minnesota at Lake Ameha 
(905 ft.). The Virginia record has been expunged, and the old Georgia 
record is very doubtful. 
18. Agrion amatum, eastern, spring. South of New England this species has 
been taken in New York, Axton (2,000 ft.), Keene Valley (3,000 ft.); in 
Pennsylvania, Charter Oak (1,000 ft.); in Maryland, near Cranesville, 
