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. 



Art. III. — Descriptive Catalogue of the North American Insects 

 belonsrinsr to the Li7i7icean Genus Sphinx in the Cabinet of 

 Thaddeus William Harris, M. D., Librarian of Harvard Uni- 

 versity. 



The 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 col- 

 lection has now become quite extensive, and contains a large 

 number of undescribed species from various parts of the United 

 States. Passing by our Butterflies, nearly all of which have been 



* PoggendorfF's Annal. vol. xxv, p. 55. 



