376 THE CRAVFIsn ciiap. 



cuticle of Ihe gizzard is calcified in places to form the si/dn'/es or 

 so-called " ossic/es'' of the gasin'i' mi//. Note the two median 

 scleiites bounding the transverse constriction in front and' behind 

 respectively. To them the anterior and posteiior pairs of muscles 

 (P- 375. § 5) «re attached, 



2. Following on the gi7zard is tlie short, thin-walled iiiid-giit, on the 

 dorsal side of which is a small uTiiini. It has no chitinoiis lining, and 

 \\\e\Aige diitt of t/ie digestive i^/aud ofiQn?, into it on either side. The 

 i/igf^/iz'if <^/atid \^ made up of three main lobes on either side and con- 

 sists of a number of small blind tubes. 



3. The iiind-giit, which runs straight to the anus. Its inner surface 

 is raised into longitudinal ridges which take a slightly spiral course, 

 and it is lined by a thin chitinous cuticle. 



4. Carefully press the gizzard backwards and note a, the hraiii, just 

 behind the bases of the small feelers ; /% the gu//et \ and r, a pair of 

 white nerve cords {(onnedivcs) coming off from tlie brain and cm- 

 bracing the gullet. Taking care not to injure these parts of the 

 nervou.s system, cut through the gullet, just above the connectives, and 

 then gently remove the whole enteric canal together with the digesti\'e 

 gland fronr the body, cutting through the intestine just in front of the 

 anus. Examine the whole digestive system under water. 



5. Note again the mid-gut and the digestive glands and ducts ; then 

 remove the digestive gland of one siile, and sketch the enteric canal 

 from the same side. Slit up the hind-gut so as to sec the ridges and 

 cuticle. 



6. Clean the walls of the gizzard and note the other .sclcrites of the 

 gastric nrill. 



.Vrticulated to each end respectively of tlie t\\'o median sclerites 

 already referred to, in each lateral wall of the gizzard, is a lateral 

 sclerite, the two articulating with one another at their other ends, so 

 that these six sclerites together fjrm a s{;)rt of hexagonal frame. Two 

 other median sclerites, arising from the median ones above-mentioned 

 respectively, extend downwards into the constriction between the two 

 portions of the gizzard, and these join below at an angle, where they 

 bear a median loolli. Each of the posterior lateral sclerites bears a 

 ZaUra/ tootli. 



Cut open the anterior end of the gizzard, and note the strongly calci- 

 fied, Ijrownish, median tool/i, and the two large /alcral tecl/i. Seize 

 hold of the two median ossicles with two pairs of forceps, one in each 



