282 Catalogue of North American Sphinges. » 
It remains to consider the elevations of whole systems of rocks, 
events which must have taken place prior to the existence of our 
records. ‘There is doubtless no difficulty in also explaining these 
phenomena through the agency of steam. Elie de Beaumont,* 
however, is of opinion, that these elevations are a consequence of 
the inequality between the cooling of the interior and exterior 
of the earth. We shall examine this subject, after pointing out 
the laws that prevail during the cooling of large masses of fused 
matter. 
To be continued. 
Arr. II.— Descriptive Catalogue of the North American Insects 
belonging to the Linnean Genus Srwinx in the Cabinet of 
Tuappevs Wittiam Harris, M. D., Librarian of Harvard Uni- 
versity. 
Te insects belonging to the order Lepidoptera have peculiar 
claims to our attention. In the adult or winged state they are 
among the most beautiful, and in their previous or caterpillar state 
are the most injurious of insects. Living while young principally 
on the leaves of plants, they are at all times more or less exposed 
to our observation, and too often obtrude themselves on our No 
tice by their extensive ravages, While it is comparatively easy 
to discover these insects and observe their transformations, the de- 
termination of their names and their places in a scientific arrange 
ment is rendered in many cases impossible, and in all exceedingly 
difficult, to the American student, from the want of suitable de- 
scriptive works on this branch of entomology. Having overcome 
these difficulties myself only at a great expense and much loss of 
time, it has occurred to me that a descriptive catalogue of our 
Lepidoptera might be useful to others, while it would serve to 
confirm the names given to these insects in my cabinet, and 
transmitted in return for specimens to my friends. My own Co™ 
lection has now become quite extensive, and contains @ large 
number of undescribed species from various parts of the United 
States. Passing by our Butterflies, nearly all of which have bee? 
fee 
* Poggendorff’s Annal. vol. xxv, p. 55. 
ies 
