THE GENUS ACRONTCTA AND ITS ALLIES. 27 



this, another diaphragm made of wood chippings and strong 

 silk occurs, this is a strong structure, and is in fact the top of 

 the cocoon proper, the burrow is often sHghtly narrowed at this 

 point, the material to form the diaphragm being obtained by a 

 rounding out of the cocoon cavity, and some superfluous chips 

 always occupy the base of the cocoon and occasionally other 

 portions, a trace of silk lines the cavity, and is more abundant 

 at the base, where the chrysalis entangles its anal spines 

 therein. No larval hairs are to be found on the cast skin, or 

 anywhere in the cavity, except in the felt diaphragm closing its 

 mouth. In emerging, the moth makes an inappreciable opening 

 in this, which closes up elastically. In the inner cover there 

 is sometimes a small circular lid, at others a triradial slit. 



The pupa (PI. IV., fig. i), length 20-22 mm., wings 11, 

 abdomen g, width 5 mm. to 5th segment, then wider, 6 mm. to 

 gth segment, then tapering to apex. Projection of spiracles 

 marked. Colour blackish-brown, with darker dorsal line, and 

 paler beneath ; wings and legs transparent, dark green nervures 

 distinct as raised ribs on the wing cases. The two hairs at 

 antennal base very minute, wings meet at end of proboscis, 

 separate again, just showing tips of hinder legs. The anal 

 armature is a boss somewhat flattened from above downwards, 

 forming a thin semicircular margin, round the edge of which 

 the ventral hooks are tolerably regularly distributed as a corona, 

 eight in number on each side, the two terminal ones being 

 more important and finely curved in a lyre shape, and the two 

 nearest the base being one above the other. The lower surface 

 of the boss is flattened, the upper rather domed, carrying the 

 two dorsal hooks, projecting upwards, slightly backwards, and 

 also with a double lyre-shaped curve. The boss is dorsally 

 finely wrinkled and pitted, margined above by a transverse 

 depression, above which again is a small rounded wrinkled 

 boss ; a special raised line or wrinkle passes down from the 

 transverse groove, between the bases of the dorsal hooks. The 

 pitting of the general pupal surface is only marked along the 

 anterior dorsal margins of the abdominal segments, and the 

 intersegmental membrane is, as in the other species, finely 

 shagreened. 



This species remains several years in pupa more frequently 

 than any other, except inegacephnla, a third of a brood will 

 often stay over the second year, and I have had several that 

 emerged satisfactorily after a third winter. 



The protection which the full-grown larvae of Acronycta have 



