HISTERIDAE. 77 



Prosternal lobe very prominent ; 



Anterior tibiae witli an internal tooth near the base. Cylistix. 



Anterior tibiae without any internal tooth. Platysoma. 



Prosternal lobe narrow, not very prominent. Omalodes. 

 Anterior tibiae with the tarsal groove badly defined, straight ; 



Middle and posterior tibiae with a single range of spines. Psilosceus. 



Middle and posterior tibiae with two ranges of spines. Hister. 



The student who will consult my paper above cited will see 

 that there are good reasons for regarding the characters here 

 given as not of generic value. 



The genus Paromalus, as above defined, is divided by Marseul 

 into two : — 



Elytra striate ; body oval, subconvex. Cakcinops. 



Elytra not striate ; body oblong, subdepressed. Paromalus. 



But these divisions are not adopted by Lacordaire and Duval. 



Sub-Tribe 2.— SaprLni. 



Some of the genera of this sub-tribe live under bark and in 

 excrements, also under stones; but the numerous species of Sa- 

 prinus are found mostly in carcasses. 



Our genera are the following : — 



Antennae inserted under the margin of the front ; antennal cavities at the 



sides of the presternum proper. Saprincs. 



Antennae inserted on the front ; antennal cavities at the sides of the under 

 surface of the prothorax ; 

 Body cylindrical ; tibiae toothed. Teretrius. 



Body oblong ; thorax with a deep groove each side ; tibiae riot toothed. 



Plegaderus. 

 Body round ; posterior tarsi 4-jointed ; tibiae not toothed. Acritits. 



The species of the last genus are the most minute of the family, 

 and are quite numerous in North America. 



The European species, formerly enrolled in Saprinus, S. rotund- 

 atus and piceus, were found by Duval to have the inner lobe 

 terminated by a corneous hook, and were therefore placed as a 

 distinct genus, Guathoncus; to the same genus belong S. deletus 

 Lee, identical with the European rotundatus, and S. interceptus 

 Lee. ; they differ from genuine Saprini by the head having no 

 stria; the sutural stria does not join the first dorsal, and is very 

 short; the epipleurse have three striae. I have not adopted the 

 genus, as these differences do not appear to me of sufficient con- 

 sequence. 



