86 RHYNCHOPHORA. 
Only one example was found of this interesting insect ; it shares the very delicate, 
upright pubescence with the next species, but this character is foreign to the species of 
Apion found in our region. 
2. Heterapion infirme, sp. n. 
Nigrum, pube erecta vestitum, femoribus flavis; prothorace brevi, parce punctato. 
Long. 13 millim. 
Hab. GuateMaLa, Zapote (Champion). 
Rostrum as long as the head and thorax, shining, punctulate; eyes separated by a 
narrow interval, which is punctate like the thorax. ‘Thorax short, a little narrowed 
in front, distinctly punctate, with a small foveiform channel in the middle in front of 
the base. Elytra striate, with convex interstices, which are indefinitely sculptured, the 
upright pubescence rather long and distinct. 
Except in the short thorax and small stature, this species is closely allied to H. femo- 
ratum. The two examples found are quite similar to one another. 
Subfam. THECESTERNINA. 
I propose to separate for the present the genus Thecesternus as a separate subfamily. 
It is placed by Lacordaire as a group of the tribe Byrsopsides, but Lacordaire’s tribe 
must be wholly dissolved, as it is composed of forms having but little relation with one 
another. I therefore separate Thecesternus and place it in the position given it by 
Leconte and Horn. 
The true position of Thecesternus is, however, certainly not here; it appears to have 
some affinities with the Australian Huomus—a genus of Amycterides—and with the 
Cryptorhynchideous division of Curculionide. But a dissection of the parts of the 
mouth and prosternum is necessary before any trustworthy opinion as to the position 
of the genus can be formed, Lacordaire’s examination of these points being inadequate. 
THECESTERN US. 
Thecesternus, Say, Descr. N. Am. Cure. p. 8 (1831) ; Complete Writings, i. p. 267. 
Lithodus, Germar, in Schénh. Gen. Cure. iL p. 420. 
This genus is peculiar to the North-American continent, one species only being 
recognized in the latest catalogue of N.-American Coleoptera; this we now find to 
extend into Mexico. 
1. Thecesternus humeralis. 
Brachycerus humeralis, Say, Journ. Acad. Phil. v. p. 254°. 
Thecesternus humeralis, Say, Descr. N. Am. Cure. p. 8°. 
Lithodus humeralis, Germar, in Schonh. Gen. Cure. ii. p. 420°. 
Hab. Nortu America? ?, Arkansas 1.—MeExico, Nuevo Laredo in Tamaulipas (Hége). 
