168 HETEROMERA. 
ZESYMNUS. 
Mentum small, trapeziform, truncate in front, the anterior angles acute; inner lobe of the maxille armed with 
a distinct tooth at the apex; last joint of the maxillary palpi securiform, that of the labial palpi stout and 
truncate at the apex; mandibles bifid at the apex ; antenne about reaching to the base of the prothorax, 
distinctly widening outwardly, the third to the fifth joints widening a little and almost equal in length, the 
sixth wider and subtriangular, the seventh to the tenth broad and transverse, the eleventh the width of, 
but much longer than, the tenth, and bluntly rounded at the apex ; head long, rather narrow, somewhat 
deeply sunk into the prothorax, unarmed and similar in both sexes, the antennary orbits but little swollen, 
gradually converging anteriorly, and impinging on the eyes behind, the epistoma broadly truncate ; eyes 
large, transverse oval; prothorax rather broader than long, the lateral margins prominent, the base 
strongly bisinuate, the angles prominent though obtuse; scutellum large, scutiform ; elytra long, slightly 
rounded at the sides, sinuate at the base, closely embracing the prothorax, regularly punctate-striate, 
somewhat broadly margined at the sides from the base to the apex (as in Ulosonia) ; legs smooth, slender ; 
the intermediate and posterior tibie in the male longer and slightly curved inwardly ; tibial spurs small ; 
the middle coxe without visible trochantin; tarsi very sparingly clothed with hair beneath, rather short 
and stout, the last joint of the posterior pair rather longer than the two following joints united ; pro- 
sternum subhorizontal, the apex slightly produced and received by the concave mesosternum ; epipleurse 
broad, extending to the apex of the elytra. 
A single species from Mexico, not very closely allied to any other described genus; it 
is perhaps nearest to a North-American species (described under the name of Metaclisa 
marginalis, by Dr. Horn) and Cyneus, but with the extended lateral margin of the elytra 
of Ulosonia. 
1. Aisymuus nitidus. (Tab. VII. fig. 23,4; 234, labium; 23 6, maxilla and 
maxillary palpus. ) 
Oblong ovate, reddish brown or piceous black, shining. Head rather coarsely and sparingly punctured, the 
epistoma slightly impressed on each side ; prothorax gradually narrowing anteriorly, widest a little before 
the base, the disc transversely impressed just before the base (the impression bounded on each side by a 
shallow oblique fovea), the anterior angles broadly produced and prominent, the surface sparingly and 
not very finely punctured ; elytra wider than the prothorax at the base, slightly rounded at the sides, 
widest about the middle, coarsely but shallowly punctate-striate (the punctures rounded), the interstices 
flat and very evidently though sparingly punctured; beneath shining, sparingly and finely punctured ; 
legs and antenne reddish brown. 
Length 6 millim. (¢ 2.) 
Hab. Mexico, Cordova (Sal/é). 
Four examples. 
MOPHIS. 
Mentum small, trapeziform, deflexed on each side; apex of the outer lobe of the maxille produced into a blunt 
tooth, the inner lobe armed on the inner side with short sete ; last joint of the maxillary palpi securiform, 
that of the labial palpi short ovate; ligula prominent, exserted ; mandibles bifid ; antenne about reaching 
to the base of the prothorax, very gradually widening outwardly, the third joint nearly one and a half 
times as long as and a little narrower than the fourth, the fifth to the tenth distinctly wider than the fourth, 
decreasing very slightly in length and feebly triangular, the seventh to the tenth subtransverse, the eleventh 
the width of but longer than the tenth, and bluntly rounded at the apex; head deeply sunk into the pro- 
thorax, unarmed and similar in both sexes, the antennary orbits a little swollen and only slightly impinging 
on the eyes, the epistoma fairly well defined and deeply emarginate in front; eyes rather large, oblique, 
