42 Prof. J. C. Scliiodte on the Tunnelling Coleoptera. 



the tci'minal joint of both pau's of palpi presented a rather 

 peculiar structure. In dry specimens this betrays itself by 

 the joint being somewhat broader than usual ; and on the 

 under surface a deep spoon-shaped cavity is observable. In 

 fresh specimens^ or such as have been boiled for examination^ 

 the hard chitinous integument seems to be wanting in this spot, 

 and to be replaced by a soft membrane_, closely covered, as if it 

 were paved, with small black polygouous chitinous warts, pretty 

 regularly disposed in quincunx. It can scarcely be doubted 

 that this is an organ of sense, a secondary palparium ; and a 

 dissection of the internal sexual organs shows that the indivi- 

 duals possessing this peculiarity are all males. Hitherto no 

 external marks of distinction between the sexes were known ; 

 but these supplementary inferior palparia are found in the males 

 of all species of Dijschirius and in many exotic species of Clivina, 

 though they are wanting in the males of Clivina fossor. 



The characters available for the distinction of species are not 

 very many. Originally authors were almost confined to the 

 variations of the external teeth on the tibise ; Erichson added 

 (Kafer d. Mark Brandenburg) the varying extension of the mar- 

 ginal striae of the elytra ; in " Danmarks Eleutherata ' I pointed 

 out some additional characters derived from the shape of the 

 clypeus ; whilst Thomson^ in ' Skandinaviens Coleoptera,^ drew 

 attention to the marginal stripe of the pronotum, which some- 

 times are wanting, and, where they exist^ extend to a varying 

 distance from the posterior corners. Two new characters may 

 be derived from the different size of the supplementary palparia 

 on the maxillary palpi of the males, and from a small difference 

 in the outline of the ligula (or^ rather, fulcrum ligulse). By 

 combining these characters, the species may be grouped with satis- 

 factory precision. But within the pale of each of these groups the 

 species are so closely connected that it is exceedingly difficult to 

 distinguish them except by a set of characters which are not 

 always as sharp as could be desired ; and one is often tempted 

 to look upon many reputed species as mere local variations. 

 But this same uniformity is observable also in other genera of 

 Scaritini, and is^ upon the whole, of frequent occurrence in 

 Arthropoda which dig or burrow in the ground, within such 

 genera as have a very wide geographical distribution. If, 

 then, those species of Di/schirius which dig their tunnels on the 

 shores of the Ganges, or in the salt-moors of Tranquebar, and 

 along the rivers of America, when carefully examined, differ as 

 little from our indigenous species as these latter do from one 

 another, we must be contei:<t to leave the matter as it is, in spite 

 of the dearth of specific characters. 



