TENTHKEDO, OE SAW-FLY. 117 



wings of your specimen are crumpled, as often happens when 

 the chief anxiety is to show the saws of the female, then you 

 had better get a male Saw-fly (Cypheus pygnmus], where I 

 doubt not they will be expanded and perfect. 



The first great rule is this : look at the costal nerve which 

 bounds the fore part of every wing, and is the main support. 

 Observe in all the Saw-flies and Ichneumons there is a dark 

 horny spot called the stigma ; from that a nerve or vein runs 

 to the front tip of the wing, dividing the enclosure into 

 one or two cells, called the marginal or radial cells. There 

 is but one in Cypheus a large oblong one. Behind this 

 cell, and running nearly parallel at a little distance, is a 

 nerve which ends at the tip of the wing, and the inter- 

 mediate space is divided into from one to four cells, called 

 the sultmarginal or mi-cubital cells, others in the centre are 

 called discoidal cells, and others, long and narrow towards 

 the base, are basal cells ; but the two former are those upon 

 which the genera are founded. Is it not wonderful this 

 invariable order exhibited by the presence or absence of one 

 tiny nerve? always present in every individual of a given 

 species throughout the world ; varied perhaps slightly, yet 

 unerringly in the adjacent species; and the progress of 

 neuration designates the rank of the species more easily 

 in this than in any other tribe of insects. The little Platy- 

 gaster, a very small Ichneumon-fly, which is noticed pre- 

 sently, has only the costal nerve and stigma no cells at all. 

 The pretty Chrysides, those scarlet and green or blue flies, 

 which rush about restlessly on windows and walls in the 

 hot sun, and are called the Humming-birds of insects, have 

 only the front wings veined, and those with but a single 

 cubital cell, and that not closed, and very imperfect sub- 

 marginal ones. And then in other genera they go re- 

 gularly increasing, until the wing is perfected in the Saw- 

 flies and Bees. It makes our microscope so much more 

 valuable when it helps us thus to a personal acquaintance 

 with the "winged things" around -us when the eye be- 

 comes educated to discern the letters of creation's alphabet; 

 for we are but children in the "First Beading-book," and 

 I doubt not there are volumes, countless and full of eternal 



