156 DESCRIPTIONS OF PREPARATIONS. 



the Silurian Blatta, possess wings, so far as can be judged, of the ordinary structure. 

 The first origin of these organs dates" back therefore to a period and to conditions 

 of which we have no record. 



Pupa and Imago of Cossus. Lyonet, Recherches sur 1'anatomie et les me"ta- 

 morphoses de diffdrentes especes d'Insectes. Ouvrage posthume, Paris, 1832. 



Changes in nervous and digestive systems, and Evolution of reproductive organs. 

 Herold, Entwickelungsgeschichte der Schmetterlinge, Cassel, 1815. Changes in 

 nervous system. Newport, Ph. Tr. 1832 and 1834. In reproductive. Bessels, 

 Z. W. Z. xvii. 1867. 



Formation of antennae of Imago. Dewitz, Biol. Centralbl. iii. 1882-3. Of 

 wing, Id. Berliner. Entomol. Zeitung, xxv. 1881. Pancritius, Z. A. vii. 1884. 



Philosophy of Pupation. Riley, American Entomologist, iii. 1880. 



31. IMAGO, MALE AND FEMALE, OF PRIVET HAWK MOTH 

 (Sphinx Ligustri}. 



IN the imago or Moth, Sphinx Ligustri reaches the last stage of its life- 

 history, the sexually mature insect. The dissimilarity between the head, 

 thorax and abdomen, which first appears in the pupa, is now far greater, but 

 the outlines of these three heteronomous regions are much softened and 

 obscured by the thick coat of hair and scales that clothes the body. The 

 small head distinguished by its light colour carries in this stage large 

 sensory organs, convex, black, pigmented eyes and antennae. As the 

 food consists of the liquid nectar of flowers the organs of the mouth are 

 reduced and modified, the only conspicuous parts being the spiritrompe or 

 antliae, the homologues of the galeae in the biting mouth, which are extended 

 in one of the specimens, and the hairy labial palpi which are, as in all 

 Lepidoptera^ turned forwards beneath the head. The thorax is broad and 

 clothed dorsally with black-brown hairs, with a streak of white hairs over 

 the roots of the wings. These organs are composed of a thin membrane 

 supported by thick nervures y the whole surface being covered with thickly 

 set and variously coloured scales, arranged in distinctive patterns and 

 characteristic of Lepidoptera. The fore- and hind-wings on each side are 

 connected by a hook and bristle. The bristle springs from the fore-margin 

 of the hind-wing near its root and ends in a tuft of stiff black hairs. The 

 hook springs from the under surface near the margin and at the root of the 

 fore-wing. The three pairs of thoracic-limbs are of but secondary im- 

 portance as organs of locomotion and are used chiefly for support The 

 tarsi end with strong claws. The abdomen is large and pointed posteriorly. 

 Its first somite is clothed dorsally with black hairs, a few white being inter- 

 mingled. The remaining somites bear a longitudinal median dorsal grey- 

 brown band with a central dark line ; and each somite except the last has 

 to either side of the median band a transverse bar of pink hairs, and a fringe 



