PUPA OF PRIVET HAWK MOTH. 153 



The maxillae expand into an angle below the eyes, and are then prolonged 

 as narrow bands lying side by side in the median ventral line, as far as the 

 tips of the wings. The labium is hidden by the maxillae. Between the 

 maxillae and antennae may be seen the tibial and tarsal portions of the 

 pro- and meso-thoracic limbs, whilst the metathoracic are completely 

 hidden by the wings. The mesothoracic, or first pair of wings, are large, 

 and hide the metathoracic pair completely, save at their dorsal origin. Both 

 wings and maxillae extend to the middle of the sternal region of the fourth 

 abdominal somite. 



The mesothoracic tergum, viewed dorsally, is of great size, whilst the 

 prothoracic, and especially the metathoracic, are much reduced. A depres- 

 sion behind the outer angle of the prothoracic tergum leads to the spiracle. 



The abdomen consists of ten somites. The first and the ninth in par- 

 ticular are small. The first spiracle is completely, the second partially 

 hidden by the wings. The third to the seventh spiracle inclusive are large, 

 but the eighth is denoted only by a well-marked scar. The tenth somite 

 is prominent. It bears a dorsal spinous projection, the cremaster, which is 

 differentiated within the anal valve of the caterpillar, and is covered with 

 spines which vary much in different specimens. It is used by the pupa as 

 a prop when it works its way up from its underground chamber previous to 

 the emergence of the imago. A longitudinal depression, ventral to the 

 cremaster, marks the anus ; and the ridges on either side of it (=sustentors 

 of Riley) correspond to the anal prolegs of the caterpillar. Irregular scars, 

 more or less evident on the ventral aspect of the third to the sixth somites, 

 denote the position of the other prolegs of the caterpillar. 



In a male pupa the ring of the ninth somite is interrupted ventrally, 

 and a depression with a more or less prominent tubercle on either side, 

 marks the future aperture of the vas deferens. In a female, the eighth 

 somite (as well as the ninth) is interrupted ventrally and bears a depression, 

 the future aperture of the bursa copulatrix. These depressions appear to 

 be constant in all Lepidoptera. 



When June approaches the pupa becomes restless and writhes in its 

 chamber. It works its way up to the surface of the ground by means of 

 the abdomen, the only part of the body which possesses the power of 

 motion. The last abdominal somites of the moth become free first of all 

 from the pupa-skin : this skin then becomes brittle and is fissured longi- 

 tudinally in the dorsal region of the thorax. A split runs ventrally along 

 the fore-edges of the wings. The moth emerges early in the day and 

 suspends itself vertically while its wings expand and dry. In two to three 

 hours it becomes capable of flight. 



The newly-formed pupa is soft : in colour creamy-white, and all its appendages 

 contain large cavities filled by a blood-plasma which is extremely milky owing to 



