262 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.43. 



Another line of modification is observed in the reduction of the 

 number of joints in the maxillary palpi. This has evidently gone on 

 independently in the New and Old Worlds, by a process of parallel 

 evolution, which might be described as orthogenetic. In the case of 

 the forms with five-jointed maxillary palpi, it is questionable whether 

 Xenoglossodes of America and the Old World TetralonieJla should be 

 kept apart. Melissodes of America is represented by Melissina in 

 India, both having four-jointed maxillary palpi. The neotropical 

 Thygater, with three-jointed maxillary palpi, is represented by 

 Thygatina in Ceylon. In South America is a genus Melissoptila 

 Holmberg, with rather numerous species, having the maxillary palpi 

 only two-jointed.* According to the theory of successive radiation - 

 it may be maintained that the true evolutionary center of the 

 Eucerines is neotropical, a suggestion which gains some support 

 from the apparent absence of the group in the Tertiary strata of 

 Europe and North America. On the other hand, the apparent 

 stem-form Teiralonia is not only especially abundant in the holarctic, 

 but appears on the wing earlier in the year than Melissodes, etc., 

 being apparently adapted to cooler conditions. We also have the 

 Asiatic series with the palpal joints reduced to four and three, and 

 there is surely no reason to suppose that in the Old World the group 

 had a southern origin. 



The North American Eucerines were last catalogued in the Trans- 

 actions of the American Entomological Society.^ Since that time 

 numerous species have been added, and a few changes in nomen- 

 clature made. The present list gives the type-localities, which were 

 omitted in the former one, and also the collectors of the types when 

 known. There are also added references to the principal synoptic 



tables. 



LIST OF SPECIES. 



Genus TETRALONIA Spinola. 



Type. — Macrocera malvae (Roesi)=antennata (Fabricius). 

 Maxillary palpi eix-jointed. 



This genus is also well represented in the Old World. 



Eusynhalonia Ashmead, type Eusynhalonia edwardsii (Creason), is a name for the 

 slightly differentiated group including this and its allies. 

 Sijnhalonia Patton has for its type Teiralonia (Melissodes) falvitarsis. 



Tables. 



(1) Cockerell. Trans. Amer. Eut. Soc, vol. 32, 1906, pp. 74-91. (Species discussed 

 in connection with the tables are included.) 



(2) Cockerell. Trans. Amer. Ent. Soc, vol. 32, 1906, pp. 94-96. (Three short 

 tables.) 



(3) Cockerell. Trans. Amer. Ent. Soc, vol. 32, 1906, p. 114 (females). 



(4) Robertson. Trans. Amer. Ent. Soc., vol. 31, 1905, pp. 366-367. (Illinois 



epecies.) 



» Bertoni and Schrottky, Zool. JahrbOcli, 1910, p. 587. 

 « Nature, Ang. 6, 1908, p. 319. 

 a Vol. 62, 1900, pp. 10l-i(M. 



