292 Dr. J. L. Leconte on the Systematic Value 
teguments are perfectly chitinized, the elytra never abbreviated 
or wanting ; the anterior coxe are always completely enclosed ; 
the ventral segments, usually five, never exceed six in number. 
The plan of degradation, in passing from the higher to the 
lower forms, is by the extension of the longitudinal axis of the 
body, in its anterior half; this is usually most strongly mani- 
fested in the head, and exhibited not only by the length of the 
beak, but by the conformation of the lower floor of the mouth. 
Commencing with those Curculionide (Adelognathi, Lacor- 
daire) in which the mentum fills the gular emargination, as in 
the higher Tenebrionidz, we find a gradual lessening in size of 
the mentum, itself becoming supported upon a broad, short, 
gular peduncle, permitting the maxille to become visible (Pha- 
nerognathi, Cohort I., Lacordaire) ; next, the gular peduncle 
becomes elongated and bilobed, receiving the mentum, now re- 
duced to very small size, between its lobes (Phanerognathi, 
Cohort II. and also Brenthide and Anthribide). 
Having, in the continuance of my work on the Classification of 
the Coleoptera of North America, recently commenced a critical 
study of our Rhynchophora, I became aware of the impossibility 
of intercalating them between the Heteromera and Subpenta- 
mera, and am now convinced that they represent a special type, 
which must be isolated from all other types of Coleoptera, pos- 
sessing a systematic value equal to all the others combined. 
In seeking for the characters which should define this type, 
I observed a remarkable difference in the arrangement of the 
pieces of the under surface of the prothorax, heretofore over- 
looked, and, so far as I know, confined to this particular type. 
In other Coleoptera the prosternum is either extended behind 
the anterior coxee, so as to form part of the hind margin of the 
segment, thus coming in contact with the mesosternum, or it is 
cut off between the coxee, and in this case (as in many others) 
the coxal cavities are open behind: in the few exceptions 
(Derodontus, Dacoderus) in which the coxe are contiguous and 
the cavities closed behind, the prosternum still extends behind 
the coxe to the hind margin of the segment, as is shown by 
the short sutures separating the epimera from the medial piece 
of the prosternum. 
I have represented these modifications of form in the adjoin- 
ing woodeuts. Fig. 1, under surface of prothorax of a Carabide 
(Pasimachus) ; the coxal cavities are closed, and the epimera and 
episterna well defined. Fig. 2, ditto of a Scarabzide (Lachno- 
sterna) ; the coxee are transverse, the cavities closed, the side 
pieces not distinct. Fig. 3, ditto of Cucujus; coxal cavities open 
behind, side pieces not distinct. Fig. 4, ditto of Telephorus ; 
coxal cavities confluent, and open behind. 
