Groups of the Lepidoptera. 323 
greater number of species in the original Bombyces. 
It is important not to overlook this fact, that here 
we have Dicranura and Notodonta, which are included 
in the Pseudo-Bombyces of the new arrangement, also 
included in a group of Latreille bearing the same 
name. This is, I think, the nearest approach to a 
justification of the new arrangement which has appeared 
in print, and it is, therefore, important to allow it its full 
influence. How slender a justification it in truth proves 
we shall very shortly find. 
The new group Pseudo-Bombyces takes away twenty- 
seven species, and separates them from all the other 
Bombyces. They are placed so far away from all the 
other Bombyces, that we are bound to believe the authors 
of the arrangement discover in those species a complete 
difference of structure, or other striking dissimilarity, 
from the remainder of the Bombyciform genera. That 
should be, of course, the sole rationale of the creation of 
the group. 
Now, that being the case, what justification or support 
does the new division of the Bombyces receive from the 
fact, that Latreille had before effected a subdivision of 
the group? Latreille’s group, Pseudo-Bombyces, so far 
from isolating at a distance from the Bombyces only 
twenty-seven species, itself includes the bulk of the Bom- 
byces ; and, what is most important, groups together, as 
allied with the separated genera, many others from which 
the new arrangement takes them away. Latreille does 
call Dicranura and Notodonta Pseudo-Bombyces ; but he 
also calls Pseudo-Bombyces the genera Cossus, Arctia, 
Orgyia, and many more, considering all these to bear: to 
the true Bombyces the same relation as is borne by Dicra- 
mura aud Notodonta, and presenting them in close 
relationship with Dicranura and Notodonta in the same 
subdivision. Latreille’s arrangement of the species in fact 
strengthens the case against the new group Pseudo-Bom- 
byces ; and though he called some genera by that name, 
they were not placed as the new group is placed, nor are 
they, as a group, distinguished by the same characters. 
But, in truth, Latreille, in his last work, divided the 
Bombyces on a very simple plan, which is found stated at 
p. 472 of his vol. of the ‘‘ Régne Animal.” His group 
Bombycites is confined to those species ‘dont les ailes 
inférieures n’ont point de frein,’ and that is the dis- 
tinction by which he was guided. 
