140 MRS, WARD, ON MICROSCOFIC TEACHINGS. 
believe my eyes; but having found several specimens, and 
shown them to some of my friends, there can be no doubt about 
the fact. Moreover, the same insect was again observed, within 
a week, by another entomologist, Mr. Duchess, of Stepney.” 
“* * % “Tt is a curious coincidence that, after remaining 
so long unnoticed, this little insect should thus be found 
almost simultaneously by two independent observers.” Mr. 
Walker at first considered the insect to be Pelynema fuscipes, 
but though allied to that species, it is not identical with it, 
the male having twelve joints in the antenne instead of thir- 
teen. Though so completely aquatic in its habits as to be 
found almost. always beneath the surface, it nevertheless re- 
quires to come to the surface at certain intervals to renew the 
air in its trachee. It seems, however, capable of remaining 
immersed for at least twelve hours. 
It is uncertain whether P. natans can also use its wings in 
flight. They are at any rate not easily incited to do so. 
The insect, like the rest of the genus, is doubtless parasitic 
in the larval condition ; but nothing appears to be known of 
this part of its history, which therefore remains an interesting 
object of research. f 
It is a very minute species and well fitted for microscopic 
observation—the female measuring 0°38 inch, and the male 
0:42. They were observed in a muddy pond from the he- 
ginning of August to the end of September. 
Microscope Teachings. Descriptions of various Objects of 
especial Interest and Beauty, adapted for Microscopic 
observations, &c. By the Hon. Mrs. Warp. 8vo, pp. 
219. London: Groombridge and Sons. : 
The demand for popular works on the microscope must ‘be 
enormous, to judge from the numbers in which they are 
produced ; scarcely a year passes without a new, little or big 
book on the microscope, or its new edition of an old and 
favourite author. And no wonder that it is so when we con- 
sider the enormous number of instruments yearly produced 
and sold. Every purchaser of a microscope, or nearly so, 
will want some instructions in its use, or some easily under- 
stood information about the various objects he sees through it. 
Books consequently are produced to suit all tastes, from the - 
scientific enquirer to the most-superficial observer, who uses 
