NORTH OF MEXICO. 321 



Two male specimens only were collected by Mr. Wm. M. Gabb, near the cent] 

 the Peninsula of Lower ( California. 

 Length .(i4 inch. 



TRIBE Xl.\ — AMPHIDORINI. 



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

 small, truncate in front ; lasl joint of palpi oval, last joint of m ixillary palpi securiform or 

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

 the sides of the front. Epistoma emarginate. Labrura moderate^ prominent, transverse, 

 basal membrane not visible, Antenna? moderately robust, third joint equalling the two 

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

 terminal being oval, more or less pointed, [ntercoxal process of abdomen usually broad, 

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



The group of genera forming this 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 arc 

 more evident. The form of head is rather that of CJpis or even Eleodes than Helops. 

 The eyes are here very feebly convex and distinctlj emarginate anteriorly by a prolo 

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

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

 Lacordaire indicates affinities in the direction of Praocis, bul any discussion of this subject 

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



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



Epipleurae broad. 



Outer joints of antennae sub-globose; first joint of hind tarsi elongal 

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

 cate; prosternum produced behind the coxae; hind tibiae of m 

 with a tooth mar apex. CRATID1 



Epipleurae narrow . 



Outer joints of antennae sub-globose ; fir^t joint of hind tarsi as long 

 as the two following ; intercoxal process broad truncate; prosternum 

 produced; mesosternum prominent. amphidora. 



Outer joints of antenna' suit-triangular ; first joint of hind tarsi 

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

 sternum not produced behind the coxa?; mesosternum not promi- 

 nent. STENOTRICHl 



