MARCH, 1862. 197 



The " areole" is a cell formed by the branches of the sub- 

 costal vein of the fore-wings. 



The "disco-central" nervule is one that rises from the 

 middle of the disk; when on the side of the median vein, it 

 will be called " medio-discal." To save space, the former 

 will sometimes be simply " the disco-central." 



The " intercostal cell" is formed in the hind-wings by a 

 junction between the costal and subcostal veins or a minute 

 communicating vein, when the two are parallel in their course, 

 called the intercostal. 



For all particulars respecting the names of the veins, &c., 

 the student is referred to a paper on the North American 

 Sphinges, contained in the Journ. Acad. Nat. Sci., July, 

 1859, where the subject is illustrated by figures. 



I regret that I have neither the material nor the time to 

 enable me to give a synopsis of the genera of each of the 

 families. The plan here adopted is perfectly applicable to 

 this purpose ; but it is scarcely the work of one who has 

 a limited collection, and by no means an extended acquaint- 

 ance with genera. For much of the information contained 

 in the various categories, I have been dependent on various 

 authors, so that I fear that now and then a family group may 

 be misplaced under a general heading not applicable to it, or 

 some detail of structure may not be correct. This I am sure 

 the student will overlook, when he considers that this is the 

 first attempt that has been made to arrange analytically the 

 numerous families of the great group Heterocera. 



It may be advisable, perhaps, to indicate the mode of using 

 the following table, in order to ascertain the family to which 

 an insect may belong, that one wishes to classify, or to ascer- 

 tain whether it has been described. 



It will be noticed that for each affirmative category there 

 is a corresponding negative category, and, as far as rny know- 

 ledge extends, each of them is absolute. Thus, the first 

 includes all Heterocerous Lepidoptera whose " wings are not 

 penniform or fissured," and an insect corresponding to this 

 will be found in its family group some place under this head- 



