98 GEO. H. HORN, M. D. 



generic characters, while the form of the last joint of the palpus is used 

 to separate tribes, but it is not a very safe character. 



Mentu^ni. — The mentum closes the mouth more or less perfectly 

 beneath usually allowing the outer side of the maxillae at base to be seen. 

 It is supported on a peduncle of the submentum the suture separating 

 them usually very distinct, rarely entirely absent as in Enceladus 26, 

 Siagona 31, Lesitignathus 65, certain Trechi 40, 41, and the Pseudo- 

 morphinae 147. The form of the mentum varies but no character of 

 systematic value has been obtained from this excepting in the Scarites 

 where it is very broad, or Drypta 76, from its nearly orbicular form. 



The epilobes of the mentum are always present in the Carabidae 

 although much inflexed when the ligula is large as in Pasimachus 19. 

 They vary greatly in size from a narrow border, as is the usual occur- 

 rence, to a very wide piece as in Schizogenius 23. Their extremities are 

 often prolonged in an angle or even an acute process as in Anophthalrmis 

 40, or Ferigona 63. The epilobes have been made use of by Chaudoir 

 in the Lebiini {q. v.) and Pogonini, in the former case erroneously 

 in the latter with very little success. 



The mentum is usually emarginate, sometimes very feebly or even 

 Brachylobus 117, truncate. At the bottom of the emargination in very 

 many genera a tooth of variable size and form occurs. The tooth is formed 

 in two ways. It may be made entirely of a prolongation of the middle 

 portion of the epilobes, or it may consist of a process of the body of the 

 mentum narrowly bordered by the epilobes. This character as well as the 

 form of the tooth will be found sufficiently represented in the sketches. 



As a general rule when the mentum tooth is well developed the 

 '■ post-dental" aetse are very small, often inconspicuous, when the mentum 

 is dee]>ly emarginate and the central portion of the epilobes membranous 

 these seta3 are unusually large and conspicuous, they are also well de- 

 veloped where the ligula is unduly exposed as in Migadops 16. I have 

 but rarely represented these in the figures for fear of confusing more 

 important parts of the mouth. 



In the emargination of the mentum we usually find a connecting 

 membrane which is the basal support of the ligula, and which varies in 

 extent in accordance with the degree of extensibility of the ligula." 



Ligula or Labium. — It seems to me better that the latter name 

 should be adopted for the entire organ as most authors in speaking of 

 ligula may mean either the whole or merely the central member. 



The labium consists of three parts, the central, usually corneovis, piece 

 on each side of which are membranous appendages called paraglossfe. 



