54 



THE YOUNG NATURALIST. 



with the suture, a diamond-shaped 

 spot behind the middle formed by 

 both elytra, and a round spot at the 



side margin, black ^topliorus 



Elytra pale, without a spot on the suture^ 

 with or without a spot before the 

 apex . , , Demetrias. 



2. Fourth joint of anterior tarsi emargi- 



nate (fig. 6, anterior tarsus of Lehia 

 chlorocephala) , 



Thorax much longer than broad 



Odacantha 



Thorax much broader than long . . Lehia 



3. Fourth joint of anterior tarsi simple 



(fig. 7, anterior tarsus of Dromius 

 linearis) . 



a. Size over I inch. 



Elytra blue black Brachinnt. 



Elytra brown or pitchy. Head con- 

 tracted behind to form a distinct 



neck, elytra parallel sided 



Polystichus. 



Head not contracted behind ; elytra 

 rounded at sides Cymindis. 



b. Size under i inch. 



Elytra blue or green . . see Brachinus 

 Elytra pale yellow, brown, or black, 

 or with dark markings; antenna2 



and legs yellow Dromius. 



Antennae and legs black or dark 



brown Blechrus, Iletabletus, 



and Lionychus. 

 B. Anterior tibise furnished with strong 

 spines Masoreus. 



BRACHINUS. 

 The commonest British species, B. crepi- 

 tam, can hardly be mistaken for any other 

 British beetle. The head and thorax are 

 bright red, whilst the elytra are deep blue- 

 black ; the antennas red, with the exception 

 of the 2nd, 3rd, and 4th joints, which are 

 more or less dusky ; and the legs are red. 

 The specific name has reference to its power 

 of defending itself from its enemies by pro- 

 ducing a discharge of acrid vapour from 

 the anus, attended with a crackling sound 



— whence the name " Bombardier" beetle, 

 which is sometimes applied to it. In the 

 Northern counties it seems to be quite 

 unknown, but where it does occur, on the 

 banks of tidal rivers, as at Gravesend, and 

 in the Isle of Wight, it is generally very 

 abundant. Two other species of Brachinus, 

 or rather one other species (Sclopeta) and 

 a doubtful species (explodens) occur in 

 England, but rarely. They are both much 

 smaller (2-3 lines). B. sclopeta, only a few 

 specimens of which have been recorded, and 

 those principally from the South coast, is 

 easily recognised by its having a bright red 

 dash at the base of the suture of the elytra ; 

 whilst explodens is said to differ from crepi- 

 tans by its smaller size, and by having 

 scarcely any distinct striae on the elytra. 



DRYPTA. 



D. dentata, the only British species, is 

 easily recognised from the description given 

 above. It is a species which measures nearly 

 \ an inch in length, but is a prize — only 

 having occurred in a few localties in the 

 south. 



POLYSTICHUS. 

 The British species P. vittatus is easily 

 distinguished from all the other British 

 Geodephaga by having a bright red streak 

 down each of its pitchy brown elytra, run- 

 ning parallel with the suture. This is also 

 a rare species, an indefatigable collector 

 like Mr. JDawson having only taken a single 

 specimen (in the Isle of Wight). 



ODACANTHA. 

 The single species, 0. Melanv/ra^ is easily 

 known by its long narrow thorax, which is 

 bluish in colour, and its elytra, which are 

 yellow-red with the apex blue-black. It 

 measures about a \ inch in length, and 

 occurs commonly in the fen district. 



iETOPHORUS. 



JEj. imperialis is sufficiently characterized 

 by the diamond-shaped black spot on the 

 suture, which is often connected with the 



