196 PROCEEDINGS OF THE NATIONAL MUSEUM Vou. 113 
elongate. In other words, they exhibit little modification of the 
basic characteristics of the genus. 
Discussion: During the early and middle parts of the Cenozoic 
Era, the climate of the larger land masses was tropical to temperate, 
with numerous low moist situations in the interior of the continents, 
according to texts on historical geology (e.g., Schuchert and Dunbar, 
1941). Thus, conditions may have been favorable for the existence 
of the parasitic plant genus Cuscuta in many places where it does not 
occur at present, including the more northern portions of the Pale- 
arctic and Nearctic Regions. In addition, it is generally agreed by 
vertebrate paleontologists and others that the Old and the New Worlds 
were connected (probably at the Bering Isthmus) at various times 
in the Cenozoic Era. If Cuscuta species were in existence at some 
time between the Miocene and Pleistocene Epochs and served as hosts 
to the early species of Smicronyr, as in many modern species of 
Smicronyx, the conditions existing during at least part of that time 
probably would have favored the attainment of an almost world-wide 
distribution by both Cuscuta and Smicronyr. As noted above (pp. 192, 
195), species of Smicronyz which breed in Cuscuta are known to exist in 
Europe, North Africa, India, North America, and South America. 
However, there are no known fossils of Cuscuta (Andrews, 1955) and 
there is thus no certainty that species of Cuscuta existed before Recent 
times. 
Some of the species of the Cuscuta-breeding groups in subgenus 
Smicronyz, although widely separated geographically, bear a strong 
resemblance to each other. This is particularly true of the species 
of the S. cinereus group of western North America and several Pale- 
arctic species, which all resemble each other in respect to body form 
and proportions, prothoracic punctation, and elytral scale pattern. 
The resemblance has been seen through examination of S. junger- 
manniae (France, Germany), S. coecus (Hungary), and S. angustus 
(Algeria) and the drawings and descriptions in the revision of the 
Central European species of subgenus Smicronyx by Pericart (1957). 
The presence of the two very similar groups of species in the Nearctic 
and Palearctic Regions is difficult to explain without assuming a land 
connection between the two areas at some time after the origin of 
Smicronyz. 
The Oligocene fossil Smicronyx antiquus (fig. 19), described by 
Forster (1891) from Brunstatt in Alsace, resembles some of the mod- 
ern species of Smicronyz, including S. cinereus Motschulsky and S. 
jgungermanniae Reich, in body form, prothoracic punctation, and 
size, but the diagnostic features of Smicronyx are either obscured or 
absent in the fossil, and therefore the latter cannot be held as definite 
evidence of the existence of Smicronyz in Oligocene times. However, 
