of some new Exotic Coleoptera. 209 



regarded as a male, especially from the shortness and breadth of 

 the muzzle and the form of the mandibles, which is another reason 

 for considering the specimens of T. IVhit'ti to be males. The only 

 specimen of T. ■i-signatus which I have seen in the British Museum 

 Collection has the muzzle much narrower than in any of the pre- 

 ceding insects, with the antennaj inserted at its base at some dis- 

 tance from the eyes ; its extremity is notched, and the mandibles 

 are minute, conical, and porrected ; the legs simple, the elytra 

 glabrous, except an impressed stria near the suture, and another 

 within the lateral margin. This specimen, I apprehend, is a 

 female.* All these insects are remarkable for having the fore legs 

 more powerful than the middle ones. They are also very valuable 

 for enabling us to determine with precision the affinities of that 

 most remarkable insect Calodromus MelU'i, with which they agree 

 in the general form of the body, excavated sides of the prothorax, 

 elongated basal joint of the abdomen and structui-e of the normal 

 tarsi. The antennae have only the three terminal joints dilated, as 

 in T. Whilii, 4-signatus, and IVestnood'ii ; whilst there are four di- 

 lated joints in T. distortus, the muzzle is not elongated in either 

 sex, the head not exhibiting any marked difference between them, 

 and the abnormal condition of the hind legs is found (in a dif- 

 ferent state of development) in both sexes. 



The very singular formation of the mandibles of the male of 

 T. distortus may be regarded, I think, as the greatest departure 

 from that law of symmetry which exists so universally in the limbs 

 of the two sides of insects. That some difference of form should 

 exist between the two opposite organs of an insect which act upon 

 each other is not surprising. Indeed it is curious that so little atten- 

 tion has been paid to this difference ; the mandibles, for instance, 

 must differ to a certain extent in the position of the teeth depend- 

 ing upon their action upon each other, and yet we find, in general, 

 a single mandible represented as affording the only necessary 

 character to be derived from the examination of the mandibles. 

 Where also the upper wings act upon each other, as in the musical 

 organs of the GrylUdce, a difference must also exist between the 

 two organs on the opposite sides of the body. In the insect before 

 us, however, there seems no necessity for the singular discrepancy 

 between the two mandibles, the extremity of the left mandible 

 extending far beyond the right one ; indeed, if I had not seen more 

 than a single specimen of the male insect, I should have considered 

 it as a monstrosity. 



• See ante, p. 184, for figures of the details of different species of Tapnroderes. 



