NORTH OF MEXICO. 



327 



Two male specimens only were collected by Mr. Wm. M. Gabb, near the centre of 

 the Peninsula of Lower California. 

 Length .64 inch. 



TRIBE XIX AMPHIDORINL 



Mentum transverse, trapeziform, and sub-trilobed ; ligula moderately prominent, 

 small, truncate in front ; last joint of palpi oval, last joint of maxillary palpi securiform or 

 triangular. Head short, deeply inserted ; eyes not prominent and deeply emarginate by 

 the sides of the front. Epistoma emarginate. Labrnm moderately prominent, transverse, 

 basal membrane not visible. Antennae moderately robust, third joint equalling the two 

 succeeding, joints four to eight obconical, equal, last three joints broader and thicker, the 

 terminal being oval, more or less pointed. Intercoxal process of abdomen usually broad, 

 truncate. Tarsi clothed with long, coarse hairs. Body clothed with erect hairs. 



The group of genera forming tins tribe has been a source of trouble to all investiga- 

 tors who have undertaken its study, and as many different opinions prevail as attempts 

 made to place it. While the group exhibits undoubted tendencies in its lower forms 

 towards the Helopini, as a whole the affinities toward the Blaptini and Tenebrionini are 

 more evident. The form of head is rather that of Upis or even Elcodes than Helops. 

 The eyes are here very feebly convex and distinctly emarginate anteriorly by a prolonga- 

 tion backward of the sides of the front. In Helops the eyes are almost entirely free in 

 front, and the margin of the head directly in front of the eyes very distinctly angulate. 

 Lacordaire indicates affinities in the direction of Praocis, but any discussion of tins subject 

 beyond the genera of our own fauna is foreign to the objects of the present paper. 



Our genera may be distinguished from each other by the following table : 



Epipleuree broad. 



Outer joints of antenna- sub-globose; first joint of hind tarsi elongate, 

 longer than the second; intercoxal process of abdomen broad trun- 

 cate"; presternum produced behind the C0X88 ; hind tibhe of male 

 with a tooth near apex. cratidus. 



Epipleuree narrow. 



Outer joints of antennee sub-globose ; first joint of hind tarsi as long- 

 as the two following; intercoxal process broad truncate; presternum 

 produced ; mesosternum prominent. ampiiidora. 



Outer joints of antennee sub-triangular; first joint of hind tarsi 

 longer than the second; intercoxal process narrow, oval at tip; pro- 

 sternum not produced behind the cox;e; mesosternum not promi- 

 ncn t. STENOTRICIIUS. 



