OBGANS OF NUTRITION. 



35 



toneil; the middle, or muscular; and the inner, or mucous. The 

 mucois coat is variously modified, being plaited or folded ; or, 



c d e h f h 



Fiff. 44. 



as in the Orthoptera and carnivorous Goleoptera, it is solidified 

 and covered witL rows of strong horny teeth, forming a sort of 

 gizzard. The aLmentary canal is held in place by retractor 

 muscles, but principally by exceedingly numerous branches of 

 the main tracheae. 



This canal (Fig. 45) is subdivided into the mouth and plia- 

 rynx^ the oesojyhagiis, supplementary to which is the cro2J, or 

 " sucking stomach" of Diptera, Lepidoptera, and Hymenoptera. 

 The proventriculus^ or gizzard ; the ventriculus^ or true stomach 

 succeed, and the intestine consists of the ileum^ or short intes- 



FiG. 44. Anatomy of Sphinx ligustri. m, i, q, the nervous cord resting on 

 the floor of the body ; at c, the ganglia form a brain-like organ, much larger than 

 the ganglia of the thorax (m) and abdomen (q). From the brain is sent off the 

 suboesophageal nerve which surrounds the gullet into which the food is conveyed 

 by the maxillse, or spiral tongue (a), which, when at rest, is rolled up between the 

 labial palpi (6). 



From the nervous cord is also thrown off a pair of nerves to each pair of legs 

 (as atm, o, p) and a branch, d, is sent off from above, distributing nerves to the 

 muscles of flight. 



The heart, or dorsal vessel (e,/), lies just beneath the median line of the body, 

 and is retained in place by muscular bands (as at /) as well as by small tracheal 

 branches. 



The alimentary canal (ft, j, ff), forms a straight tube in the head and thorax ; ft, 

 the crop, or sucking stomach, Avhich opens into the oesophagus; j, the true, chyle- 

 forming stomach, which contracts posteriorly, and then dilates near its anal outlet 

 into a cloaca (indicated at g, but not distinctly, as it is concealed by the numerous 

 urinary vessels). The urinary vessels also indicated at ff, form long tubes (which 

 correspond to the kidneys of Vertebrates), opening into the pyloric end of the 

 stomach. The position of the testes (/j)is the same as that of the ovary, and the 

 dotted line I shows the course of the eflferent duct {vas deferens) and also of the 

 oviduct of the female. 



The numerals indicate the number of segments of the body, which in the Lepi- 

 doptera, consists of twenty, the 21st, or 11th abdominal, being absent. — F?-om 

 Newport. 



