NORTH AJVIERICAN GEOTRUPINAE — HOWDEN 163 



and metathoracic legs often with stridulatory organs (Bolboceras, 

 Peltotrupes, Geotrupes). 



The genus Pleocoma was included in Ritcher's (1947, p. 5) key to 

 Geotrupinae, as were the Imown European forms. Pleocoma has been 

 omitted because of the present uncertainty over its inclusion in the 

 subfamily Geotrupinae. For descriptions of the larvae in the genus 

 Pleocoma and the European genera Lethrus and Typhoeus the reader is 

 referred to Ritcher's (1947) excellent paper. 



Key to the North American tribes and genera of known Geotrupinae 



larvae 



1. Metathoracic legs greatly reduced; last abdominal segment obliquely flattened; 



body sharply bent with swollen abdomen (pi. 11, figs. 1, 2). (Geotrupini) . 2 



Metathoracic legs not reduced; last abdominal segment rounded posteriorly; 



body slightly bent without enlarged abdomen (pi. 12, figs. 1, 2; pi. 13, fig. 1). 



(Bolboceratini) 4 



2. Third antennal segment less than one-sixth as long as second segment (pi. 7, 



fig. 6) ; abdomen greatly swollen Peltotrupes 



Third antennal segment at least one-fourth as long as second segment; abdomen 

 moderately swollen 3 



3. Endoskeletal figure of ventral anal lobe below anal opening laterally expanded 



with sharp, fairly truncate angles Geotrupes 



Endoskeletal figure of ventral anal lobe below anal opening lacking sharp 

 angles, broadly rounded Mycotrupes 



4. Legs lack claws, 2-segmented; penultimate segment of antenna (pi. 6, fig. 3) 



bearing a single conical sense organ; lower anal lobe single (pi. 6, fig. 10). 



Bolboceras 



Legs with claws, 3- or 4-segmented; penultimate segment of antenna with two 



or more conical sense organs; lower anal lobes paired 5 



5. Penultimate segment of antenna (pi. 6, fig. 2) with two conical sense organs; 



galea emarginate; legs 4-segmented Bolbocerosoma 



Penultimate segment of antenna (pi. 6, fig. 1) with more than two (usually four) 

 conical sense organs; galea not emarginate (pi. 6, fig. 6); legs 3-segmented. 



Eucanthus 



(Larvae of the following genera are unknown: Bolbelasmus, Bolborhombus, Brady- 

 cinetulus and Bolbocerasies.) 



Genus Bolbocerosoma Scliaeflfer 



Bolbocerosoma Schaeffer, 1906, p. 254. — Boucomont, 1911, pp. 332-350. — 

 Blatchley, 1910, p. 937; 1928, p. 29.— Dawson, 1922, p. 194.— Dawson and 

 McCoUoch, 1924, pp. 9-15. Brown, 1928, pp. 192-195; 1929, p. 213.— 

 Robinson, 1941, p. 132.— Ritcher, 1947, pp. 11-12. 



Genotype : Scarabaeus Jarctus Fabricius, designated by Schaeffer 

 (1906). 



Generic limitations: Given by Schaeffer (190G, p. 254): "Eyes 

 completely divided, intermediate intercoxal process between the 



