1918.] F. H. (iRAVEiA-: Passalidae of the World. 29 



The central tubercle is very vaiiaMi' in shape and size, and is iaifier in females than in 

 males. P. cornultis differs from P. slrialopiinctatus in its larger size, somewhat shorter 

 antennal lamellae, evenly arched anterior margin of dypeus, pedunculate and larger 

 central tubercle, unpunctured pronotum, pro.sternum usually more broadly truncate behind, 

 mesothoracic episterna with a broad matt band parallel to but not in contact with the 

 lower margin, unpunctured jjosterior intermediate areas of metasternum, and more finely 

 punctun-d clytial grooves. 



The above species of Popilius may be distinguished from one another thus : — 

 f The clypeus more or less broadly flattened and trapezoidal . . . . . . 2. 



1 ■< Tlie ciypeus transversely linear or distinctly prominent in the 

 V. middle line . . . . . . . . . . . . . . 7. 



.^ \ The central tubercle elongate, with free forwardly directed ape.\ P. reclicornis, p. 'IG. 



\ The central tubercle small, its apex not free . . . , . , . . 3. 

 ^ The antennal lamellae long, equal to about four of the 



] immediately preceding joints in length . . . . . . , . 4. 



] The antennal lamellae short, equal to about two of the 



^ immediately preceding joints in length . . . , . . . . 5. 



The frontal ridges short and curved, together forming almost 

 a semi-circle . . . . . . . . ..P. ttmrginalu.s , p. 27. 



The frontal ridges long and approximately straight, meeting in 



a slightly obtuse angle . . . . ..P. nmazonicus, p. 27. 



The central tubercle situated in, or a little in front of, the 

 middle of the head ; the frontal ridges well developed, long 

 and approximately straight, meeting in an obtuse angle . . P. in'.ergeneus. p. 27. 



The central tubercle situated a little behind the middle of the 

 head ; the frontal ridges weaker or absent . . . . . . . . 6. 



The clypeus straight ; the frontal ridges forming a semi-circle in 



front of the central tubercle ; the parietal ridges grooved . . P. guatemilae, p. 27. 

 The clypeus lightly ^curved ; the frontal ridges absent, or 



extending straight to the obsolete frontal tubercles from 



either side of the base of the central tubercle at about a 



right-angle to each other ; the parietal ridges keeled . . n 



The clypeus linear, parallel-sided, lightly recurved ; the central ^P. tropicus, p. 28. 



tubercle sometimes with free apex, but never pedunculate j 

 The clypeus with at least the posterior margin straight ; or 



the central tubercle pedunculate . . . . . . . . , y. 



The anterior margin of the clypeus with a strongly developed 



median convexity, the central tubercle not pedunculate . . . . , . 9. 



The anterior margin of the clypeus at most lightly convex 



medially, the central tubercle pedunculate .. .. P. cor/iif/i/.f. p. 28. 



f The central tubercle of moderate size, its apex scarcely free . . P. hrerioripeinii.i. p. 2S. 

 Oj The central tubercle large in both sexes (especially the female). 

 (. its apex entirely free .. .. ,. .. P. strinto-puitciniiis. p. iS. 



8 



