270 
NORTH AMERICAN GYRINUS (cOLEOPTERA) 
among those of the entire world, and the handicap of a foreign 
language, counterbalance the gains and leave us about where 
we were before. 
1 hav(! on several occasions, without much success, endeav- 
ored to find out something about our (dyrini by a comparison 
of my material with LeC'onte’s types, l)ut the ])resent study 
dates rather definitely from an investigation begun in the sum- 
mer of 1916. At the end of Dr. LeC'onte’s paper, a footnote 
states that a portion of a large school of Gyrinus collected by 
Uhler in the Cdiarles River near Cambridge, ■Massachusetts, 
contained the following six species: liNihatiis, dichrou!^, confinis, 
frntermis, picipes ? (race), lugens.” The author goes on to 
remark; ‘‘1 have observed however at Lake Superior that the 
species are generally not found intermixed.” On the twenty- 
ninth of August, 1916, while canoeing on Lake Quannijiowitt 
at Wakefield, (Massachusetts, I encountered a large school of 
Gyrinus. A good deal of variation in size was obvious, and 
having in mind LeConte’s note, I determined to investigate on 
my own account. Cyrini are not easy to capture without a 
Met, lull with some sort of dipper I managed to secure about 
fifty specimens, which on sorting carefully seemed separable 
into about six species. Seeking further possilile confirmation 
I tried the experiment of removing the genitalia^ for compari- 
son. The results were gratifying in the extreme. Not only 
wi're my six sipiposed species sharply separable by the mak' 
gimital organ, but one of the six proved to be composite, giving 
nu' a seventh species. Subsetiueiit study showed the seven 
s])eci('s to !)(' as follows: ventralis, conjinis, liiyens, dichrous, 
pernitidu.H, rockinyhamensis and (upiiris. 1 have on anothi'r 
occasion takim ajfiuis at tlui sanu' jilace in late August, and havi' 
lit lie doubt it was also jii'i'sent though noiu' wi'i’o si'cured. 
In th(' hit(‘ summer of 1917, Mr. C. A. tk'ost of Li'amingham, 
Massachusi'tts, while on his vacation in southwi'stei-n Maine, 
kindly colk'cted foi' me a lot of Gyrinus. In most instanci's, Mr. 
k'l'ost ti'lls m(!, all specimens bearing same locality and date Avere 
' I was iiol al this t-iiiu^ aware* (hat Ldwards and Sharp had alrc'ady used 
(Ids met hod of analysis in thoir study of (ho Hritish species of (li/rittus, and 
Sharp’s excellent, papt'r of I'.M 1 has come to hand only after the practical 
completion of iny own study. 
