Scientific Misccllanv. ^i ' 



so that even the present rapid rate of discovery will not complete 

 our collection of insects in less than 1,000 years. Before the end 

 of that period many species ot to-day will have become extinct, 

 and Dr. Sharp urges that those likely soon to disappear should be 

 especially sought. 



An interesting problem to astronomer and philosopher is the 

 remarkable ring of minor planets traveling in orbits between those 

 of Mars and Jupiter Over 270 of those little objects have been 

 discovered, and Prof Daniel Kirk wood now gives the encourag- 

 ing assurance that the number unknown is practically unlimited. 

 He shows that Jupiter is probably tending to reduce the number 

 by increasinc^ the eccentricities of their orbits until their perihelion 

 distances fall within the sun itsell. He believes that several of 

 our periodical comets may have been asteroids, drawn from their 

 orbits in this way. 



Two telegraph wires, each about six miles long, are to be laid in 

 Spain expressly for studying earth currents and atmospheric 

 electricity. The lines will cross each other at the astronomical ob- 

 servatory of San Fernardo, one running due east and west, and 

 the other due north and south. 



The channel of the Congo can be traced for a hundred miles 

 out to sea as a remarkable submarine valley, having a depth of 

 1,432 feet just at the river's mouth. 



A curious speculation has been made concerning what would 

 happen were the earth's rotation to cease. The equatorial di- 

 ameter being twenty-six miles more than the polar diameter, the 

 earth would present an equatorial zone of solid ground miles high 

 above sea level, the water being drawn to the poles. This land 

 zone would then be like our artic regions, and would be banded 

 by a ring of permanent ice and snow. 



CO LIAS EURYTHEME, BOISDUVAL. 



Ever since the summer of 1877, when my eyes were gladdened 

 by the profusion of Colias edusa in Kent and Sussex, England, 

 the genus Colias has had a kind of fascination for me. But it was 

 not until last ye ir when I made the acquaintance of Colias eury- 

 theme, C. Meadii and C. Alexandra in this country, that I fully 

 understood the extreme interest attaching to the various forms of 

 Colias, and most of all to the polymorphic C. Eurytheme. This 

 species may be considered to belong to the central region of North 

 America, though it exists to' the Pacific, and occasionally occurs 

 as far east as Massachusetts, as well as in Ontario and Quebec. 

 It is double-brooded, and so different is the spring from the sum- 

 mer race that it was formerly considered a distinct species, Colias 

 Iveewaydin. There are also two other distinct forms, called 

 ariadne and eriphyle, and the last was like Keewaydin, supposed 



