208 PROCEEDINGS OF THE NATIONAL lirSEUll. VGI..XX. 



marked on -the prozona by the flavous stripe bordering the piceous patch ; 

 median carina percurrent, dull and heavy, more pronounced on the pro- 

 zona than on the metazona; front margin subtruncate, feebly and nar- 

 rowly flaring in the male, hind margin broadly and roundly but not 

 deeply einarginate; prozona punctate next the front margin, distinctly 

 longitudinal (male) or quadrate (female), mesially twice as long (male) or 

 fully half as long again (female) as the finely punctate metazona. Pro- 

 sternal spine appressed conical and slightly retrorse (male) or erect, 

 conical (female), rather long and slender ; interspace between mesosternal 

 lobes transversely subquadrate (male) or a little transverse (female), the 

 metasternal lobes subattingent (male) or somewhat approximate 

 (female). Tegmina about as long as the prozona, elliptical, about three 

 times as long as broad, broadly rounded at tip, lateral, widely distant, 

 black with testaceous veins. Fore and middle femora somewhat en- 

 larged especially in depth in the male ; hind femora flavous, more or 

 less longitudinally infuscated or ferruginous, especially on or next the 

 carinae, the genicular arc piceous, the lower genicular lobe wholly pallid ; 

 hind tibiae pale dull flavous, delicately mottled with ferruginous, the 

 spines black excepting at base, eight (female) or ten (male) in number 

 in the outer series. Abdomen feebly carinate, nearly uniform in color, 

 the extremity subclavate in the male, a little recurved, the supraanal 

 plate triangular, roundly acutaugulate at tip, the surface vaulted, with 

 a large subbasal rounded basin taking the place of the usual median 

 sulcus, and into which falls the furcula, consisting of a pair of very 

 slender, parallel and adjacent, subequal, cylindrical fingers, extending 

 less than a third the distance across the plate; cerci slender, gradually 

 incurved but otherwise straight, compressed blades, tapering at the 

 very base, but beyond subequal, rounded at tip, considerably shorter 

 than the supraanal plate; subgeuital plate small, subpyrarnidal, of 

 about equal breadth and length, the margin apically angulate, entire. 



Length of body, male, 17.5 mm., female, 31.5 mm.; antennae, male 

 and female, 11 mm. ; teginina, male, 3 mm., female, 5 mm. ; hind femora, 

 male, 12 mm., female, 17 mm. 



One male, 1 female. Tepic, Jalisco, Mexico, November, Coll. Calif. 

 Acad. Sc. (L. Bruner) ; Cape St. Lucas, Lower California ( ?), J. Xautus. 



The female, collected by Xantus (presumably at Cape St. Lucas), is 

 the one referred to by me in my original description of M. aridus as 

 belonging to that species, but it differs from it (and agrees with M. 

 ImmpJireysU] in the emargiuation of the posterior border of the pro- 

 notum, and differs from both in the greater robustness of the body, 

 especially in the metathoracic region. It is quite possible that the 

 male and female here brought together do not properly belong to one 

 species; there is great disparity in size and, as the description shows, 

 some unusual disagreements between sexes of the same species; but 

 they certainly belong in close proximity, even if distinct; if they should 

 prove distinct, the name should be retained for the male, from which 

 the description (especially in colors) has principally been drawn. 



