nictitans group of the Genus Hydroecia. 749 
of breeding the larvae of the different species side by side. 
Even if this were done, the larvae, being concealed 
feeders, would probably present no characters to readily 
distinguish them from each other, or from a considerable 
number of allied species, which are abundantly distinct in 
every aspect. 
It may, however, be pointed out from the “ geographical 
variation” point of view, that /ucens and paludis, the 
most distinct from each other of all the species in ordinary 
characters, especially colour, have habitats that are mostly 
distinctly specialised and separate for each of them; and 
at the same time that the genitalia of these two species 
are least abundantly distinct from each other than those 
of any other pair of species. It is therefore highly prob- 
able that these two forms are the most recent in separating 
from one another, and if any one chooses to call them 
geographical forms, I probably differ from him less as to 
facts than as to definitions of terms. 
EXPLANATION OF PLATES LELViint 
Pr. LI. Male appendages of H. nictituns x 11. 
3 Ns H. paludis x 10. 
- H. lucens x 9. 
- a H. crinanensis x 10. 
3 +9 H. americana, Spr. x 9. 
(H. atlantica, Smith). 
The lettering is explanatory. 
Pr. LI. Extremities of 9 abdomina of H. nictitans x 13. 
» 9 - Hi. lucens x 12. 
” ” ” ff, paludis <qulgle 
” ” ” H. crinanensis x 18. 
The lettering is explanatory. 
Pp, LIII-LVIII. Photographs of ¢ appendages and of 9 end 
segments. 
Lin. nictitans & x 15, @ x 18. 
Livy. paludis nse, Guus: 
LY. lucens aK 16,9) 97. 
LVI. crinanensis ¢ x 16, 2 x 8. 
LVIL americana g x 13, 2? x 18. 
LVIIL. asiatica 6 x 14. 
