MEMOIES OF THE i^ATIOI^AL ACADEMY OF SCIENCES. 
45 
Upon the whole, the Ceraiocampidw are tropical, many more species occurring in Brazil and 
Central America than in North America, and this may be said of the family Hemileucidm. 
The family Satimiiidce is a tropical group, only a single genus occurring in Europe, while in 
North America north of Mexico there are six. In tropical America, Africa, and southeastern 
Asia, including China, the species and genera are far more numerous and form a characteristic 
feature of the fauna. 
Another family richly developed in the tropics of South America, Africa, and Asia is the 
extensive family of Lasiocampidw, many of them rivaling in size the colossal Attaci, and judging 
from a collection of Central African caterpillars of this group in the museum of Brown University, 
collected on the Upper Congo, their armature of spines is tlie most formidable of any of the 
Bombyces. And here it may be observed that the most s^iiny forms appear to be tropical, and 
this tends to prove that originally nearly all our spiny caterpillars appeared in warm regions, 
while the densely hairy forms, like Arctian larvae, imedominate in cool temperate regions. 
The Psifchi'dw, though so richly developed in Europe, appear on the whole to be widely 
distributed over the tropical regions, including Australia. 
The group of Cochliopodidw or slug caterpillars is richly developed in Central and South 
America, as well as in India, but is entirely wanting in western North America, while in Europe 
there are only two species, this paucity or absence of species being probably due to geological 
•extinction in the westermportions of the Old and New Worlds, 
The small family of Megalojipgidce (Lagoidie) is confined to the New World, One genus ( Lagoa) 
occurs in the eastern United States, but the species are most, numerous in the forest regions of 
eastern South America. 
Tlie family Liparidm appears on the whole to exist in greater force in the Tropics of America 
and Asia tUan in the temperate regions to the northward. 
On the other hand, the extensive group of Arctiidw and LithosUdw predominate in the tem- 
perate regions, and its species, in rare cases — a few of Arctia — extend to the Polar Eegions, only 
one other genus, Laria, a Liparid, sharing the regions of the Arctic Circle, a species of each genus, 
Arctia and Laria, also being Alpine in Europe and North America. 
We will proceed to analyze the Notodontian fauna of North America, 
The animals of our American continent south of the Polar Eegion may roughly be divided 
into three grand assemblages, i. e., (1) those inhabiting the northern moist and forest-clad regions; 
{2) those inhabiting the elevated, dry plateau region of the Cordillera mountain ranges, extending 
southward over the Mexican plateau, and which may be called the Plateau Province (it is Allen’s 
Arid Province) ; (3) those inhabiting the tropical portions of southern Florida and the low tropical 
shores of southern Texas and of Central America. 
In our essay on the geographical distribution of the Geometrid moths, ^ imbhshed in ISTd, 
we called attention to the elements from which our present insect fauna has been formed, and 
claimed that the tropical elements in our fauna originally migrated from Central America by 
three avenues, i. e., the Pacific Coast, the central plateau of the Cordilleras, and the Atlantic 
Coast, and we have always been of the. opinion that the Mexican fauna had strongly inlluenced 
the Pacific Coast fauna, as well as the fauna of New 3Iexico, Utah, and Nevada. 
As to the Arid province, or Plateau province as it might also be designated, it may be observed 
that within the limits of the United States it comprises the Central pi'ovince of Agassiz, together 
with the Pacific Coast or California province, and to which Dr. Allen gives the name of Camiies- 
trian subprovince. The southern equivalent of the Campestrian is the Mexican subprovince. We 
very much prefer the word Mexican to the term “Sonoran” of Dr. Merriam.^ Originally the term 
“Sonoran” was applied by Cope to a restricted portion of northwestern Mexico known politically 
as Sonora. 
But Dr. Merriam has, somewhat unwarrantably it seems to us, extended the. term “Sonoran” 
to include not only the elevated portions of Mexico, but also almost the whole of the United States 
'A monograph of the Geometrid moths or Phahenidic of the United States. Report TJ. S. Geological Survey, 
F. V. Hayden, geologist in charge, Vol. X, 1876. 
‘The Geographic Distribution of Life in North America, with special reference to the Mammalia. Proc. 
Hiological Society of Washington, vii, pp. 1-64, April, 1892. With a map. 
