470 COLYDIIDZ. 
dorso ante medium utrinque tuberculo parum arguto, obtuse cariniformi, instructo; elytris subtilius 
seriatim punctatis, plica intra-humerali brevi. ; 
Long. 4—7 millim. 
Hab. Mexico, Villa Lerdo in Durango, Jalapa (Hoge), Cordova (Sallé), Motzorongo 
(Flohr) ; Guatemata, Cerro Zunil, Capetillo, Purula (Champion) ; Costa Rica, Caché 
(Rogers) ; Pawama, Volcan de Chiriqui 2500 to 4000 feet (Champion). 
The thorax is elongate and very little narrowed towards the front; the pliciform 
elevation limiting the intermediate line is strongly elevated and continued to the front, 
its termination there being only very slightly curved inwards; the two median lines 
are very definite, diverging but little towards the base, and commencing abruptly a 
little behind the front margin; about as far forward as their anterior part there is 
an obscure, elongate, scarcely tuberculiform elevation. The fine fold at the shoulder 
of the wing-case is quite short. 
This species, like the following, is represented in our collections by a good series of 
specimens; though the two are variable and very closely allied, they can always be 
distinguished, but small narrow examples of A. didentatum are at first sight difficult 
to identify. 
4. Aulonium bidentatum. 
Colydium bidentatum, Fabr. Syst. Eleuth. ii. p. 556°. 
Aulonium bidentatum, Chevr. Ann. Soc. Ent. Fr. 1863, p. 607 *. 
Oblongum, subdepressum, nigro-piceum vel piceo-rufum, antennis pedibusque dilutioribus ; prothorace sub- 
nitido, sex-sulcato, sulculis intermediis externe vix carinato-limitatis, sulculis mediis leviter impressis, 
posterius divergentibus, dorso ante medium utrinque tuberculo sat arguto instructo; elytris subtiliter 
seriatim punctatis, plica intra-humerali elongata. 
Long. 4-7 millim. 
Hab. Mexico, Jalapa (Hoge), Cordova, Toxpam, Vera Cruz (Sallé), Motzorongo 
(Flohr), Temax in N. Yucatan (Gaumer); Britis HonDuRas, Belize, Rio Hondo, Rio 
Sarstoon (Blancaneaux) ; GuatTeMaLa, Panima, Tamabu, San Joaquin, and San Gerénimo 
in Vera Paz, Zapote, Cerro Zunil, Las Mercedes, El Tumbador (Champion) ; Nicaraaua, 
Chontales (Belt) ; Costa Rica, Caché (Rogers); Panama, Bugaba, Volcan de Chiriqui 
(Champion).—Soutn America!; Cua ?. 
This species and the preceding though very closely allied may, in the series before me, 
be in all cases distinguished. The diagnoses are drawn so as to express the distinctive 
characters, which are as follows: the better impressed median lines of A. tubulum, 
which also are less divergent behind ; the form of the thorax—more narrowed in front 
in A. bidentatum and with the intermediate cariniform elevation turned more inwards 
and more tuberculiform on the front margin. In A. twbulum the median impression 
on the front of the thorax is deeper, and the intermediate carina more elevated, while 
the tuberculiform elevation near the front margin on each side of the middle is elongate 
