F . 
THE @SOPHAGUS, STOMACHS AND INTESTINES. 407 
3. THE ESOPHAGUS, STOMACHS AND INTESTINES, AND 
THEIR ACCESSORY GLANDS. 
a. The Alimentary Tract (Plate XXIV.). 
The cesophagus, crop, proventriculus, chyle stomach, proxi- 
mal intestine, distal intestine, and rectum constitute the 
alimentary tract. 
The wsophagus commences at the posterior extremity of the 
fulcrum, and, curving sharply backwards, passes between the 
supra- and infra-cesophageal nerve-centres and through the 
cephalo-thoracic opening; above the great nerve-trunk and 
beneath the dorsal vessel and median splanchnic nerve, which 
are in relation with it. 
In the thorax it lies upon the thoracic nerve-centre and 
the metasternal entothorax, immediately beneath the chyle 
stomach, with the coiled salivary glands on either side of it. 
It passes back into the abdomen and enters the great pyriform 
bi-lobed crop. 
Immediately below the proventriculus, it gives off a short 
vertical tube, the proventricular cesophagus, which enters that 
organ and transmits the food to the chyle stomach. 
The Crop (Pl. XI., s s) occupies a considerable portion of the 
base of the abdomen, and lies behind, below, and between the 
great abdominal pulmonary sacs (Pl. XIL., ps). 
Structure.—The muscular coat of the cesophagus is thicker 
than that of the rest of the alimentary canal, and both the 
longitudinal and circular fibres are well striated, and resemble 
those of the ordinary skeletal muscles; the muscle fibres of 
the crop are indistinctly striated, and are flattened bands 
which anastomose with each other, and present large meshes 
when the organ is distended. 
The epithelium of both consists of thin pavement cells; the 
cuticular intima is very thick in the cesophagus, and is thrown 
into permanent longitudinal folds, into which the epithelial cells 
penetrate as they do in the crop of the larva. The cuticle of 
the crop is thin, and does not exhibit any distinct infoldings. 
