150 [•^•""^. 



my friend :— the egg of purpurella when laid is "OMl inch ; on fourth 

 day "0179, whilst the cubic contents are as four when laid to eleven on 

 the fourth day ; sixth day, egg no longer but a little thicker, soon after 

 which it hatched. 



I will now describe, but in the barest outline, the apparatus 

 itself. Within the abdomen of the insect, lying above the viscera and 

 working free in the general cavity, are two pairs of strong, black, 

 chitinous rods, reaching from the anal extremity two or more segments 

 upwards, according to the distension of the abdomen. To the proximal 

 end of each rod are attached powerful muscular bands, which pass 

 backwards to be inserted in the under-side of the last dorsal plate, or 

 its neighbourhood. The distal ends of the lower pair of rods are united 

 to the last ventral phite ; and their use is to open the anal orifice, 

 afford an anchorage on the surface of the leaf at the commencement 

 of the operation — a very necessary provision, for I have seen uni' 

 maculella make repeated efforts, her abdomen slipping time after time 

 before she succeeded in getting a hold — and later on to advance the 

 point of the ventral plate within the orifice of the pocket and keep it 

 on the stretch. The upper pair of rods are united to the corners of 

 a very beautiful and complicated instrument, which we may call the 

 knife blade. Its extremity, at least in Micropteryx, has very much 

 the shape of a surgeon's lancet, but instead of the cutting edge it is 

 armed on each side with a fine saw. Its use, and, up to a certain 

 point, its mode of action by the alternate working of the rods are so 

 self-evident, that it is unnecessary to dwell upon them. The knife is 

 provided with a sheath, and both are concealed within the abdomen 

 when not in use. 



I have incidentally mentioned Incurvaria as a genus having the 

 same kind of instrument, and there are others hereabouts similarly 

 provided, but, strange to say, that part of Micropteryx of whose larvae 

 we are ignorant does not appear to possess it ; at any rate, calthella, the 

 only species I have yet examined, has an ordinary ovipositor. Under 

 these circumstances it will be necessary to divide Micropteryx, retain- 

 ing perhaps the caUhella group under the old name, and referring the 

 purpurella one to the other leaf-cutting genera, which it might be 

 convenient to elevate into a distinct family, should their general 

 affinities allow of it. 



Tarrington, Ledbury : 



May lUh, 1890. 



