640 Coleopterological Notices, VI. 



in the reentrant fingle at the base of the prothorax, where it 

 bristles with a sparse fringe of long cilia.* 



As these characters are unusual and abnormal, a perfect con- 

 stancy of form or extent is not to be expected, and the occurrence 

 of transitional groups, in which the mesosternum is variously de- 

 veloped according to the species, might be anticipated. In point 

 of fact, we actually find that in some generic groups, the form and 

 extent of the mesosternum are as constant as the thoracic process 

 of Notoxus — another abnormal structure, — or even more so, but 

 in a few others, such as Vacusus and especially Hemantus, they 

 become variable subgenerically, but still onl}^ to a slight extent 

 specificall3^ The occurrence of these remarkable structures has 

 alone compelled me to increase considerably the number of gen- 

 era, but it should be mentioned that in every case the validit}' of 

 the genus is confirmed b}' other marked peculiarities of special 

 structure, and also by general habitus. 



The North American genera of the tribe may be outlined 

 as follows : — 



Pronotiim without an elongate corneous process near the apex 2 



Pronotum with a large anteriorly porrect subapical process 11 



2 — Anterior coxal cavities closed behind, to a certain degree, by an oblitera- 

 tion of the usual posterior emargination; prothorax strongly constricted be- 

 hind the middle, the depression extending more or less feebl,y across the 

 dorsal surface; mesosternum extending in one large unbroken plate to 

 the sides of the body, the lateral edges ciliate and largely visible from 

 above 3 



Anterior coxal cavities widely open behind, their corneous floor broadly and 

 deeply emarginate posteriorly 4 



3 — Head olilong, the eyes very small and anterior; body densely and minutely 

 sculptured and pubescent DilandillS 



Head more oval or sulKjuadrate, the eyes larger and submedian in i)osition; 

 body small and su))glabrous Foi'inicilla 



4 — Penultimate tarsal Joint generally just Aisibly dilated, deeply excavated 

 or longitudinally grooved above and feebly lobed beneath, the last joint 

 inserted discally and far from the apex; elytra entire or nearly so, 



* It is true that LaFerte alludes at some length to this character under the 

 description of Formicomtts hporinus (Mou., p. 93), but in such a way as to 

 show that he failed completely to grasp its meaning, or to realize its far-reach- 

 ing taxonomic value in the tribe, his description proving that he even failed to 

 examine the under surface of the insect at all, and I am some^vhat surprised 

 to find that the character is passed over even more lightly by Mr. Champion 

 in his description of F. nracUipes (Biol. Cent. -Am er., IV, 3, p. 220). 



