On the Lamellicorn Beetles of the Genus Peltonotus. 153 



The above description is taken from a number of apterous 

 forms received from different localities. Nacebus is allied to 

 Rhagadotarsus, Biedd., from which it differs by the structure 

 of the head and thorax. 



Nacebus dux, sp. n. 



Body above and beneath, antennae, rostrum and legs black; 

 pronotum, anterior femora (excluding apices), acetabular, 

 coxse, and trochanters ochraceous ; disk of mesonotum and 

 abdomen distinctly more opaque in coloration ; structural 

 characters as in generic diagnosis. 



Length (inch anal append.) 4 mm. 



Bab. Calcutta. L. Burma ; Mudon, Amherst Distr. 

 (Annandale). 



At Calcutta the species was foi*id in the tanks. 



XIX. — On the Lamellicorn Beetles of the Genus Peltonoius 

 with J [descriptions of four new Species. By GILBERT J. 

 Arrow. 



(Published by permission of the Trustees of the British Museum.) 



I SUGGESTED in a recent paper (Trans. Ent. S )c. Lond. 

 1908, p. 355) that the genus Peltonotus should be transferred 

 from the Dynastidse, in which it has hitherto been placed, to 

 the Rutelidte. These two groups have the closest relation- 

 ship and no natural and obvious line of division appeals 

 between them. Almost the only definable distinctive features 

 of the Dynastinse, as it is perhaps preferable to call them, 

 are the fixed and equal claws (at least of the four posterior 

 leg.-) and the concealed labrum, and neither of these charac- 

 teristics is found in Peltonotus. The former feature, how- 

 ever, is infringed by various species of the Cyclocephala 

 group of genera, in which group also the clypeus, normally 

 reduced in the Dynastina 3 , is large, as in the Rutelinae, 

 while the mandibles on the contrary are small. In this 

 group Peltonotus has hitherto been included, but in the 

 remaining differential character (the rudimentary and con- 

 cealed labium) it is strikingly different, for the labrum is 

 largely exposed and highly chitinized. This connects the 

 genus more nearly to the Rutelinae than to Cyclocephala, 

 the only genus of Dynast inre with which it can be compared. 

 The horizontally extruded labium appears to be a survival of 



