216 
Psyche 
[September 
NOTES ON THE STRUCTURE AND SIGNIFICANCE 
OF PALAEOGYRINUS 1 
By P. J. Darlington Jr. 
The beetle family Palaeogyrinidae was erected by D. H. R. 
von Schlechtendal in 1894 to contain the single genus Palse- 
ogyrinus, described from the obverse and reverse of a single 
fossil specimen from the Upper Oligocene deposites of Rott 
in Siebengebirge, Prussia. Concerning the later vicissitudes 
of the genus it should be sufficient to say that Handlirsch, 
in “Die Fossilen Insekten” placed it directly in the Gyri- 
nidae, leaving it there, without a query, in Schroder’s 
“Handbuch” and that Hatch 2 has recently removed it and 
placed it as a separate subfamily of the Dytiscidae. 
The characters given for the genus by von Schlechtendal 
were simple and striking. The most important was the com- 
pression of the tarsi of the middle legs for swimming, and, 
if the figure which accompanies the original description is 
accurate, the tarsi were very highly specialized indeed. The 
undivided eyes and the presence of a mesosternum larger 
than that of the Dytiscidae were considered of secondary 
importance. Von Schlechtendal’s figure, which is repeated 
by Hatch, shows the external structure of the beetle in some 
detail, but, when considered in conjunction with the text, 
is obviously in part a reconstruction. Except for the tarsi, 
the insect is almost wholly dytiscoid. 
Much might be written of Palaeogyrinus as originally de- 
scribed, indeed remarks on its significance as a link between 
the Dytiscidae and the Gyrinidae have already been 
iContribution from the Entomological Laboratory of the Bussey 
Institution, Harvard University, No. 320. 
2 Bulletin Brooklyn Entomological Society, 1927, Vol. 22, No. 2, 
p. 89: On page 94 will be found a bibliography of reference to 
Palaeogyrinus which need not be repeated here. 
