Sesia tipulifornii.s and Trochilium apiformc, Linn. 187 



oesophagus, (2) the crop, (3) the stomach, (4) the intestine. 

 The last is distinctly divided into the small and large intes- 

 tine, and is furnished with a blind branch (the ctecum). The 

 oesophagus is a very long and narrow tube, wliich is gradually 

 dilated at the lower end, and thus forms a large sac-like crop, 

 opening into the oesophagus at the wide part. The stomach 

 is of an oval sha])e, very narrow at each end. The small 

 intestine is much more slender ami does not form any expan- 

 sions. At the commencement of the intestine appears a pear- 

 shaped branch, which is the blind intestine (caicum). 



"With regard to the morphological importance of the diges- 

 tive apparatus, I think it possible that it represents about 

 lialf the usual development in typical Lepidoptera. But the 

 peculiar structure of the croj) indicates an arrest of develop- 

 ment in the pupa-stage. The crop does not communicate 

 with the middle of the oesophagus, as is normally the case in 

 Lepidoptera, but is placed near the lower end and communi- 

 cates with the hinder part, not by means of a long slender 

 canal, but, on the contrary, it opens into the oesophagus at 

 the broad end, imperceptibly passing into the sac-like portion. 

 The crop is formed thus in the last stage of the development 

 of the digestive aj)paratus in the pupa, when it is not placed 

 any more forward, and its commencement does not form a 

 stalk. 



The salivary glands are feebly developed. They consist of 

 two long slender tubes, one end of wliich opens into the lower 

 part of the mouth ; the other end is usually rounded. 



The Malpighian vessels present no peculiarity, being 

 arranged on the usual type found in Lepidoptera. On each 

 side of the alimentary canal are two vessels, opening into the 

 commencement of the small intestine. Each vessel consists 

 of two tubes, one of which is simple, but the other forms a 

 connexion between the two vessels. Near the openings of the 

 two Malpighian vessels they form a very small oblong expan- 

 sion, the rudiment of a urinary bladder. 



The heart or dorsal vessel is a long and rather narrow 

 tube with several constrictions. There are eight chambers 

 and attachments for the alee musculares on the dorsal surface. 

 The respiratory system is arranged as follows : — There are 

 two large respiratory tubes on the ventral surface, running 

 along the whole trunk of the insect, and communicating with 

 it by means of two transverse arching tracheaj. At the hinder 

 end of the body they are connected by means of a transverse 

 tube. Numerous fine branches are distributed to the various 

 internal organs, and from these also run smaller transverse 

 branches which communicate with the spiracles. The air- 



