PHYSIMEKUS. 75 



the anterior angles depressed, the sides marginate ; at the base is a 

 transverse depression which extends obliquely upwards towards the 

 humeral angles ; the surface is finely punctate, sparingly clothed 

 throughout with pubescence. Scutellum minute. Elytra subparallel, 

 slightly broader than the thorax, and attenuated at the apex ; punc- 

 tate-striate, and clothed throughout with a very fine and sparingly 

 .distributed silken pubescence. Antenna) filiform, fuscous. Legs fla- 

 vous, suffused irregularly with fuscous. 



Mexico. In the collection of M. Chevrolat. 



6. Physimerus ambiguus. (Tab. III. fig. 2.) 



P. oblongus, subdepressus, subparallelus, robustus, nigro-cyaneus ; 

 capite brevi, rufo ; thorace transverso, ad basin depresso, punc- 

 tato, rufo; elytris punctatis (striispene obsoletis) ; antennis jili- 

 formibus, robustis, fuscis, ad basin mifis ; pedibus nigris. 



Long. corp. 2 lin., lat. | lin. 



Oblong, slightly depressed, subparallel, robust, of a dark metallic- 

 blue colour. Head short, depressed, very slightly elongated; be- 

 tween the eyes is a transverse canaliculation, the extremities of 

 which are deflected upwards towards the upper and inner margins of 

 the eyes ; this canaliculation is shallow and almost obsolete : eyes 

 slightly prominent, large, and distant; maxillary palpi dark fuscous; 

 surface of the head roughly punctate and rufous. Thorax rectan- 

 gular, transverse (almost quadrate) ; the sides are slightly marginate 

 and (when viewed laterally) considerably depressed in front; the 

 surface of the thorax subconvex, with an obscure transverse basal de- 

 pression, coarsely punctate and rufous. Scutellum triangular, black. 

 Elytra distinctly punctate, the punctures being arranged in the form 

 of striae (the striae themselves being almost obsolete, not so distinct as 

 in P. agilis), smooth, of a metallic bright blue, clothed very sparingly 

 throughout (more distinctly at the apex) with pubescence ; an ante- 

 medial transverse and shallow depression (which extends upwards 

 on either side towards the humeral angles) gives an appearance of 

 prominence to the shoulders. Antennce filiform, fuscous, with the 

 base of the terminal joints rufous ; the first joint dilated towards its 

 extremity and curved outwards ; the second short, oval ; the third, 

 fourth, and fifth attenuate; the sixth to the eleventh with a slight 

 tendency to dilatation. Legs black, with the base of the tarsal joints 

 and the posterior apical claw rufous. 



There are apparently two forms of this insect : one (the typical 

 form), in which the thorax is transverse (almost quadrate), and the 



