MAY 2 1 1910 
The Ohio V Naturalist * l , 
PUBLISHED BY 
The Biological Club of ihe Ohio State University. 
library 
NEW YORK 
botanical 
QARDKN ! 
Volume X. 
MAY, 1910. 
No. 7. 
TABLE OF CONTENTS. 
Williamson— A New Species of Celithemis (Order Odonata) 153 
Laughlin — Twenty-five Rare Plants at Barnesville, Ohio 160 
Parker— Notes on the Nesting Habits of Bembex Nubilipennis 163 
O’Kane — T he Ohio Powdery Mildews 166 
A NEW SPECIES OF CELITHEMIS (ORDER ODONATA). 
E. B. Williamson. 
While calling on Professor Hine at the Ohio State University 
last autumn he showed me 4 specimens of Celithemis collected by 
himself at Slidell, Louisiana, July 2-6, 1905. The species was 
unknown to both of us, and he very generously turned the 
material over to me for study. This study had not progressed 
far when it became evident that the real difficulty would lie in 
determining which of two species Kirby had before him when 
he described his Celithemis fasciata, to which species numerous 
specimens from Ohio and Indiana collected by Kelhcott and his 
students and co-laborers had been referred. In working out 
the differences between the northern (Ohio and Indiana) speci- 
mens and those from Louisiana, however, it became clear that 
the name fasciata would have to go to the southern species, and 
that the better known northern species required a new name. I 
informed Professor Hine of this and he kindly requested me to 
complete the study and send him the paper for the Ohio Natur- 
alist. 
Reasons for assigning Kirby’s name fasciata to the Louisiana 
specimens and describing the Ohio and Indiana specimens, for- 
merly called fasciata, as a new species, monomelaena: 
1 and 2. In Kirby’s description he says: “Triangle (front 
wing) crossed by one or two nervures, followed by 4 rows of cells.” 
His figure shows the triangle with 2 crossveins and 4 posttrigonal 
cells on each side. (It is possible that the venation shown in 
the figure has one side duplicated on the opposite side by the 
artist.) Referring now to these characters in the material before 
me I find that the 4 Louisiana specimens ( fasciata ) have 5 front 
wings with 2 crossveins and 3 wings with 1 crossvein in the triangle, 
153 
