158 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
A number of years ago I discovered that all the adult West Indian 
Phyllophaga are distinguished from the continental American forms 
by possessing spined middle and hind tibiae and by nearly or entirely 
lacking a tibial carina. In 1937 I called these tibial characters to the 
attention of Drs. A. G. Boving, E. A. Chapin, Milton Sanderson, and 
others. From Dr. Béving I learned that he could separate the West 
Indian larvae from those of the continent and so was pleased when 
he agreed to accompany the present paper on the taxonomy of the 
adults with a paper concerning the taxonomy of the larvae.t The 
conclusions reached independently by Dr. Boving and myself, on the 
limits of the genera discussed herein, are practically identical. 
TRIODONYX,’ new genus 
Male and female practically inseparable as to the external characters 
(antennal length, robustness of body, abdominal characters, etc.). 
Male abdomen with the fifth and sixth sternites plane as in the female. 
Clypeal suture straight or nearly so, Labrum about three-fifths the 
width of clypeus and slightly projecting in front of clypeus, widely 
and deeply cleft at middle. Each claw with a very strong median 
tooth, an obtusely rounded and not at all prominent basal dilation, 
and a third small but very distinct tooth between the dilation and the 
median tooth. Anterior tibia tridentate. Hind and middle tibiae 
each with traces of a transverse carina visible only at each side; inner 
posterior margin slightly crenate. Spurs of hind tibia free, usually 
slender. Abdomen convexly rounded, the transverse sutures hardly 
visible; sixth segment short, free, plane in both sexes. Propygidium 
with a broad, flat, median longitudinal sulcus, about one-twelfth the 
width of the pygidium, the margins of the sulcus slightly overhanging. 
Male genitalia symmetrical, tubular and very large for the size of the 
insect. Other characters as in Phyllophaga. 
Genotype—Phyllophaga gigantissima Saylor. The species, de- 
scribed by me in the April 1935 issue of the Revista de Entomologia 
(vol. 5, p. 33), was based on two male specimens; since that time I 
have seen a small series of both sexes, all from the State of Sinaloa, 
Mexico. 
The genus is distinct from Phyllophaga, sensu stricto, in the charac- 
ters given above; the close similarity of the two sexes, especially in 
the abdominal characters, is surprising. 
The two tarsal teeth in addition to the small basal dilation are, to 
the best of my knowledge, found only in the genotype and in P. 
lalanza Saylor and P. ecostata Horn. These three species are the only 
1 Proc. U. S. Nat. Mus., vol. 92, No. 3146. 
2 tri, three + odous, tooth + onyz, claw. 
