iS94.] 355 [Packard. 
dipterous stem before the existing forms of Diptera had become 
so extremely specialized as we now find them to be. 
The points which now need working out are the following : 
(1) the embryology, with reference to the presence of temporary 
abdominal legs ; the development of the labium, and the presence 
or absence of the imaginal discs of the wings ; (2) the presence 
or absence of rudiments of wings in the pupa. 
LITERATURE. 
Bonnet, G. Memoire siir la puce penStrantc ou chique. Arch. med. 
uavale, v. 8, 1867. Extrait: Ann. sci. nat., ser. 5, zool , v. 8, p. 105- 
138, 1867. 
Duges, Ant. Recherches sur les caracteres zoologiqnes du genre Pnlex et 
sur la raultiplicite des insectes qu'il renferme. Ann. sci. nat., ser. 1, 
V. 27, p. U5-164, 1832. 
Guyon, M. Histoire naturelle et medicale de la cliiqne (Rhynchoprion 
penetrans Oken), insecte parasite des regions tropicales des deux 
Ani§riqucs. Rev. et mag. zool., 1865-68. 
Karsten, H. Beitrag zur kenntniss des Rliynchoprion penetrans. Bull. 
soc. Unp. nat. Moscou, v. 37, p. 72-156, 1864. 
Kraepelin, K. Ueber die systeraatisclie stellnng der puliciden. Ham- 
burg, 1884. 
Kiinckel, Jules. Observations sur les puces en particnlier sur les larves 
des pnces de chat et le loire. Ann. soc. ent. France, ser. 5, v. 3, p. 
129-144, 1873. 
Laboulbene, Alex. Metamorphoses de la puce du cliat. Ann. soc. ent. 
France, ser. 5, v. 2, p. 267-274, 1872. 
Landois, L. Anatomie des hundeflohes (Pulex canis). Dresden, 1866. 
Packard, A. S. Embryological studies of hexapodous insects. (Devel- 
opment of Pulex canis). Mem. Peabody acad. sci., Salem, Mass., 
1872. 
Taschenberg, 0. Die flolie. Halle, 1880. 
Wagner, J. Aphanipterologisclie studien. I. Anatomie der Vermipsylla 
alacurt Schiink. Horae soc. ent. Ross., v. 23, p. 199-261, pi. 7-11 , 
1889. 
Also the Avritings of Balbiani, Bouche, DeGeer, Haliday, Kolenati, 
Kiinckel, Lacaze-Dnthiers, Mayer, Moleschott, Newman, Ritsema, 
J. Wagner, Westwoo:!, and Weyenbergli. 
