AMERICAN COLEOPTERA. 101 



the table. In the Harpalinse it is of less importance generically. In 

 Cydosomns the tip is much prolonged and acute. 



Anterior CoxiE. — The cavities receiving these are always closed 

 except in a small number of tribes of Carabinae. In many cases the 

 positive determination of open or closed cavities can only be made by 

 separating the prothorax. 



Mesosternum. — The mesosternum separates the middle coxae nar- 

 rowly, not often widely {Slagona and some Carabinje), rarely the coxal 

 cavities are confluent (certain z a; n i n i). In front it is usually oblique 

 or nearly flat, rarely protuberant and carinate (some Carabinae). The 

 side pieces, epimera and episterna, by their form and extent give to the 

 division of the entire family one of its most important characters. In 

 the first sub-family Carabinae the epimera nearly equal the episterna 

 in size and reach the coxal caAaty. In the other two sub-families the 

 epunera vary in width but do not reach the coxae, and in some tribes 

 are extremely narrow, in fact linear or even partly hidden externally 

 by the episterna. 



Mormolyve is one of the most remarkable exceptions in the entire 

 family. It is plainly by its structure otherwise, allied to the Truncati- 

 penne series but the mesosternal epimera reach the coxae ; nor does the 

 exception end here, the metasternal episterna also form part of the outer 

 side of the coxal cavity, a character otherwise unknown in the Adephaga 

 outside of the Dytisci complicati (PI. Ill, fig. 3). This gives an answer 

 to the closing lines of Dr. Sharp's paper. (Comptes rendus Ent. Soc. 

 Belg. Sept. 1880). 



Metasternum. — This segment yields nothing of importance in the 

 classification of the family, its structure has given us the means of 

 dividing the Adephaga in a satisfactory manner. The side pieces are of 

 less importance than those of the preceding segment, the fusion of the 

 two pieces in one has been made use of but its importance exaggerated. 

 I have seen in the same species the epimera free or united with the 

 episterna without suture {Mefrius). 



Posterior Cox^. — While it has been observed that the middle 

 coxae are sometimes contiguous, it seems to have escaped notice that 

 the posterior are equally variable. In the vast majority of genera the 

 coxae are contiguous although at times the contact is small and produced 

 by a slight extension inward of a small process of the coxae as shown in 

 PI. Ill, fig. 2. The metasternum and abdomen are however completely 

 separated, as efiectually as in those genera in which the contact is 

 ' larger. This is the form observed in Pterostichini, Lebiini and 



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