TRANSACTIONS 
OF THE 
AMERICAN ENTOMOLOGICAL SOCIETY. 
VOLUMK NVIII. 
.4 iiioiiograpli of the species of CRYPTOHYPNUS of 
Boreal America. 
BY GEORGE H. HORN, M. D. 
In the printed and other comments which were made on Dr. 
Hamilton’s paper on the distribution of many species in common 
in the Arctic regions of both continents, my attention happened to 
be drawn especially to this genus from the fact that several forms 
had just appeared which seemed to be identical with those of Europe, 
and which had not, as yet, appeared in our lists. These were made 
the subject of a short note, in “ Entomological News,” which closer 
study has shown me to be inaccurate in many of its statements, due 
in part to the lack of types, and as much to important omissions of 
details in the best European descriptions. The subsequent pages 
will show that several of our forms are parallel with those of Europe, 
in fact deceptively resembling them, but are readily separated by 
excellent structural characters hitherto unobserved. 
The number of species of Cryptohypnus known being less than 
one hundred, has not made it unwieldy or difficult to handle, conse- 
quently but little attempt has been made to subdivide it. C. G. 
Thomson, in his Skand. Col. vi, restricts the name Cryptohypnus to 
those species which have the prosternal sutures straight and Negas- 
trius to those with the sutures arcuate, although he seems to place 
TRANS. AM. ENT. SOC. XVIII. ( 1 ) JANUARY, 1891 . 
