258 
[October 
specievS is mucli slenderer than our insect, and has altogether a very 
different appearance. Does this insect belong to some genus of Cordu- 
lina not hitherto found in N. A. ? or will it, when the S is discovered, 
constitute a new genus ? Of Cordulia, besides the five described spe¬ 
cies, there are no less than nine undescribed N. A. species in M. Selys’ 
collection from Canada, Nova Scotia, &c., two of which G. Franklmi 
and Richardsoni are said to be the representatives of the European 
0. alpestris and arctlca. (Mon. Gromph. p. 78.) There can be no doubt 
that this insect belongs to Cordulina, because the posterior edge of the 
eyes is conspicuously tubercled. 
To prevent misconception it may be stated here, that in all my 
measurements of the Odonatous body and abdomen the abdominal ap¬ 
pendages are included, and that the width of the wings is measured, 
unless otherwise specified, at the widest place. 
The character given on page 141 of the Synopsis to separate the 
subfamily Libellulina from the subfamily Cordulina, “beginning of the 
2nd series of postcubital spaces with no transverse veins,” should be 
stricken out and appended to the characters of the Tribe Libellulina, 
p. 182, for it is common to both subfamilies, Cordulina as well as 
Libellulina. The following Synoptical Table, compiled chiefly from 
scattered passages in the Monograpliie des Gomphines^ Mon. des Ca- 
lopt. and the Synopsis JV. A. JVeur., briefly expresses the more obvi¬ 
ous relations of the six subfamilies of the great Family Odonata. I 
have retained the systematic nomenclature employed by Dr. Hagen in 
the Synopsis for the sake uf uniformity, though I agree with Leach in 
considering Odonata to form two distinct families, Agrionidae and Li- 
bellulidse—as it certainly must if we accept Prof. Agassiz’s definition 
of the term “family”—the former including Dr. Hagen’s subfamilies 
Calopterygina and Agrionina, and the latter his remaining four sub¬ 
families. In the Monograpliie.^ on the other hand, Messrs. Selys and 
Hagen consider Odonata not as a family.^ but as a suborder.^ and Leach’s 
two families they call tribes, and divide them into the three families 
Agrionidm, ^schnidae and Libellulidse, which are again dichotomously 
divided into the same six subfamilies defined in the Synopsis by Dr. 
Hagen, except that instead of the termination ina they employ 
inse to designate the subfamily, as does also Prof. Baird in his work 
