224 [October, 



this feature is present in some of my examples. The same author in 

 his note on A. puberula, Sharp (Fn. GI-allo-Ehenane, p. 704, ohs. 2), 

 states that this insect only differs from A. liliputana in havin» the 

 thorax smoother, the antennae black, the abdomen a little more distinctly 

 punctured, and in being twice the size. To the above I may add that 

 A. liliputana is a parallel- sided insect, in point of size intermediate 

 between A. inquinula and A. morti(nrnm, and although the punc- 

 turation is fine it is rather rough. From A. inquinula, its broader, 

 more robust build, broader and flatter head, and different puncturation 

 will distinguish it; whilst from J., mortuorum it may be separated by 

 its smaller size, much more shining head and thorax, and more finely 

 punctured abdomen. 



It is, of coin-se, very difficult to draw up a table to distinguish 

 species whose characteristics are, in the main, comparative, but I en- 

 deavour to do so in the hope that it may be of some use in the elucidation 

 of the British members of the sub-genus Microdota, Rey. 



Small or very small species (length 0.7 to 2 mm.), with trans- 

 verse thorax and parallel- sided abdomen. 



A. Fourth joint of antennae strongly transverse. 



1. Length not exceeding 1 mm. 



(«) Puncturation of head and thorax fine but distinct, 



length 0.7 mm. [inquinula 

 (h) Puncturation of head and thorax almost effaced, length 1 mm 



[perexigua 



2. Size larger. 



(a) Species in great part testaceous palleola 



{h) Species dark. 



(1) Head, thorax, and elytra dull mortuorum, atricolor* 



(2) Head, thorax, and elytra shining. 



(ft) Legs dark or pitchy atomaria 



(b) Legs testaceous amimda 



B. Fourth joint of antennse quadrate or but slightly transverse. 



1. Species in great part reddish-testaceous segra 



2. Species dark. 



(a) Legs dark ijidubia 



(b) Legs testaceous, thighs sometimes sliglitly infuscate. 



(1) Head and thorax very finely, sparingly, obsoletely punc- 



tured puberula 



(2) Head and thorax with distinct pimcturation. 



(a) Size larger, more robust, less parallel ...subtilis, 



[indiscreta* 



{b) Size smallei", narrow, more parallel liliputana 



H.M.S. "Attentive," 



Home Fleet : 

 Sept. 8th, 191 L 



* 1 do not know these species, but they must be very similar to A. mortuorum and 

 A. subtilis respectively. 



