258 



REVISION OF THE TENEBRIONID/E OF AMERICA, 



TRIBE II GNATHOSIINI. 



Body variable in form, apterous; epistoma in our genera with at least a prominent 

 middle lobe, labrum prominent ; mentum large ; ligula and maxillae concealed ; pro- and 

 mesosternum not contiguous. Tarsi variable in vestiture. 



Our genera may be arranged — 



Intcrcoxal process of abdomen broad, truncate. 



Pronotum continuous with the flanks; middle lobe of epistoma short) broadly emarginate, 



lateral lobes very prominent. craniotus. 



Marginal line of thorax distinct. 



Mandibles toothed above. trioroimius. 



Mandibles not toothed above. 



Hind tarsi with first joint equal to 3 — 4. stiwa. 



" tarsi with first and last joints equal. Tiui'irAT.Tis. 



Intercoxal process of abdomen narrow, acute. 



Middle lobe of epistoma rounded; eyes with superciliary ridge. TBIMYTIS. 



Middle lobe of epistoma truncate; eyes with superciliary ridge. ctcyptadius. 



Middle lobe of epistoma emarginate; eyes without " " AUCHMOBUJS. 



The last three genera may be distinguished from the preceding genera by their robust 

 form. The body is convex, and in two genera quite globose. The sides of the thorax 

 arc regularly rounded and narrow gradually from the basal angles. The base of thorax 

 is as wide as the base of the elytra. The form of the body is therefore regularly oval. 

 The head is also less prominent and more transverse than in the preceding genera of the 



tribe. 



CRANIOTUS, Lee. 

 Craniotus, Lee, Ann. Lye. V, 143. 

 0. pubescens, Lee., Ann. Lye. 5, 142, the only species of the genus known. 



The genus may be readily distinguished from all others of tin; tribe by the very prominent 

 triangular lateral lobes of the head. The median lobe is very short and broadly emarginate, 

 labrum prominent, feebly emarginate, anterior angles rounded. The c pi pleural and the 

 elytra are connate without trace of suture. The metastcrnal parapleural are broad and 

 without epimcra. The antennuc are longer than the head and thorax, third joint equal to 

 fourth and fifth. The last joint is small, conical and connate with the preceding, so that 

 the antennae appear to have but ten joints. The last joint of the maxillary palpi is 

 broadly triangular, the apical side larger in the male, and much more narrow in the fe- 

 male. Craniotus is not rare on the Maricopa desert of Arizona under fallen trunks of 

 Cereus giganteus, from March to November. 

 Length .45-50 inch. 



TRIOROPHUS, Lee. 



Triorophus, Lee, Ann. Lye. V, 141. 



In Triorophus the mandibles have a superior tooth which clasps the sides of the promt- 



