274 
NORTH AMERICAN GYRINUS (cOLEOPTERa) 
111 his paiior on the British species of Gyrinns, Sharp saysS 
“Th(' species of this genus a’-e lialile to a peculiar form of vari- 
ation, the chitin of the upper surface — more especially of the 
('lytra — liecoming more or less dull instead of highly polished, 
and this dullness is sometimes accompanied by the develop- 
ment of an excessively minute and indefinite sculpture. As 
sculiiture is of considerable importance in discriminating the 
siiecies of the genus, it is desiralde that the student should be 
prejiared to recognize this adventitious roughening of the sur- 
face when he meets it.” The same abnormal sculpturing has 
been oliserved in occasional examples of a considerable number 
of our species, and it is probable that all are subject to it. 
Although many thousand examples of Gyrinus have been 
passed in review in the preparation of the present paper, less 
('ffort than usual has been made to obtain material from a wide 
range of correspondents. Something doubtless would have 
been gained by so doing; I have, however, seen representatives 
from most portions of our territory, and I do not anticipate 
that the number of new species yet to be discovered within 
our limits Avill be very great. As already indicated I am es- 
pi'cially indebted to IMr. C. A. Frost and Air. J. B. Wallis for 
l;irg(' collections made in Maine, ATassachusetts and Alanitoba. 
Prof. J. (\ Bradley has sent me practically the entire material 
in (lyrini of the Cornell University Collection, containing long 
series takim in the vicinity of Ithaca, and these together with 
contributions from Alcssrs. Woodruff, Notman and Davis, 
have enabled me to determine pretty definitely the character 
and extimt of the (lyrinid fauna of central and eastern New 
\ oik. From Prof. H. F. Wickham I have received a repre- 
s('ntativ(' lot of tlu' sjiecic's taken by him in Iowa, and on his 
miiiK'rous collecting trips in the far west. I am also indebted 
lor siiecinums to Alessrs. A. B. ^^’olcott of ('hicago, F. ^^d 1 ,ldo 
Dodge ol Ab'lrose Highlands, Alassachusetts, Prof. A. P. ATorse 
ol \\ (‘Ih'sh'y, Alassachusetts, ('has. Dury of C'incinnati, Warren 
Ixnaus ol McPh(*rson, Kansas, Drs. Blaisdell, \4in Dyke and 
f’enyes of ( 'alifoiaiia, and Prof. .1. B. Alalloch of Ib'bana, Illi- 
nois. \ (‘ry esi)(‘cia,l thanks are due to Di’. (lahan and Mi'. 
Arrow oi the British Museum of Natural History for si'iiding 
MiiiloinolojrisPs Moiitlily Miifiiiziiic, .liuu' 191 I, j). 180. 
