MR. A. G. BUTLER ON THE SPHINGIDZ. 589 
22. 'TRIPTOGON MAACKII. 
Smerinthus maackii, Bremer, Bull. del’ Acad. Sci. St. Pétersb. iii. (1861) ; Lep. Ost-Sibiriens, p. 34. 
no. 153, tab. i. fig. 11 (1864). 
Ussuri. 
25. 'TRIPTOGON MODESTA. 
Smerinthus modestus, Harris, Sill. Journ. vol. xxxvi. p. 292 (1839); g, Strecker, Lep. Rhop. & Het. 
part 7, p. 60, pl. vii. fig. 11 (1873). 
Laothoé modesta, Grote, Bull. Buff. Soc. Nat. Sci. i. p. 24 (1873). 
Smerinthus princeps, Walker, Lep. Het. viii. p. 255. no. 21 (1856). 
Canada, Lake Superior, New England, &c. (Strecker). 2, B.M. 
This is unquestionably the proper place for this species. 
Genus 8. LaotHok, Fabricius. 
Laothoé, Mliger’s Mag. vi. p. 287 (1808). 
1. LaoTHo POPULI. 
Sphinz populi, Linnzeus, Syst. Nat. i. 2, p. 797. no. 2 (1766). 
Polyptychus populi, Hibner, Verz. bek. Schmett. p. 141. no. 1517 (1816). 
Smerinthus populi, Godart, Hist. Nat. Lép. France, iu. p. 71, pl. 20. fig. 3. 
Laothoé populi, Grote, Bull. Buff. Soc. Nat. Sci. i. p. 24 (1873). 
England [Brit. Coll.] ; Europe (Becker). B.M. 
I find, after a careful comparison of the Smerinthus modestus of Harris with L. populi 
that they differ so much in structure from one another, that I cannot follow Mr. Grote 
in placing them in the same genus. The form of the wings, the direction of the disco- 
cellulars, and the length of the branches of the subcostal nervure, will at once distin- 
guish them. 
I have not thought it worth while to refer to the hybrid form between this genus 
and Smerinthus, although Mr. Strecker gives it, in his work, a distinct heading, as if it 
were a species. 
2. LAoTHOE TREMULZ. 
Sphinx tremule, Treitschke, Schmett. Eur. x. 1, p. 140 (1834). 
Smerinthus tremule, Duponchel, Hist. Nat. Lép. France, Suppl. ii. p. 29, pl. 2. fig. 2. 
Moscow. 
