INSECT VARIETY. 245 



The chrysalis now emerges at a rupture at the anterior upper 

 part of the integument, with the third or fore-wing-hearing 

 ring of the body most capacious, an enlargement effected 

 by a contraction of the following four segments. From this 

 torpid pupa, in due time, issues the active imago or perfect 

 insect, exhibiting a further metamorphosis, for the fifth 

 and sixth segment have been reduced to dorsal arcs, forming 

 a pedicle by which the abdomen is united to the thorax, 

 and the skin of the lower arc of the seventh has become 

 consolidated to protect the lateral front edges of the ventral 

 region. 



In all the aforementioned moths, the organ attributable with 

 hearing (a) is found between these contracted segments and the 

 metathoracic that immediately precedes them, and projecting 

 posteriorly, it may be said to occupy the transverse section of 

 the fourth, fifth, and sixth rings. It is bounded in front by the 

 muscles of the metathorax ; behind it is encased in a saddle- 

 shaped tube, varying in consistency from the most delicate white 

 membrane to a hard, yellow, opaque substance which the needle- 

 point chips with difficulty, as seen in the Red Underwing. The 

 external ear {a) is at once recognised in a largish canal, or 

 meatus, that here penetrates the body at either side, somewhat 

 oval in section, with a posterior concavity or conch, that 

 occasionally is seen to extend as far back as the termination of 

 the seventh segment, or third of the abdomen, conferring to the 

 mouth in the female Dark Arches an extreme length of 'Z'", and 

 dej)th of 1'". 



The adjuncts of the auditory canal are xmiformly present, 

 and consist in a minute protuberance in the conchoidal cavity 

 posteriorly (Plate IV., Fig. 9, w) ; semicircular in profile in the 

 Dark Arches (X. Pol//odou) ; lanceolate, clothed above with 

 smooth hair, in the Red Underwing (C. Nuptd); or very elongate 

 and spatulate, as in the Silver Y, or Gamma Moth. Placed 

 behind at the origin, and concealed by this protuberance, is 

 the opening of an air-tube or spiracle, Avhich perhaps should be 

 considered as belonging to the metathorax. The other adjunct 

 is somewhat singular; it is a little membranovis valve, with a 

 fringe of hair (y), triangular in shape, attached at the front of 

 the auditory canal, and connected by a muscular ligament to the 



