141 



last tarsal joint, the pulvillus, bears two claws. Under 

 each tarsal joint there is a soft pad. 



Write an Account of the Alimentary Canal of the Cockroach. 



On the floor of the mouth or buccal cavity, and above the 

 labium, there is a fold, the lingua or tongue or hypopharynx. 

 A narrow gullet or oesophagus passes, through the neck, 

 into the expansive crop which is separated by a constriction 

 from the pear-shaped proventriculus or gizzard. The 

 muscular gizzard has six internal teeth and six pads with 

 setae. All these parts are lined with cuticle and represent 

 the stomodaeum or fore-gut. The next portion is a short 

 tube, the mid-gut or mesenteron, with seven or eight 

 hepatic caeca at its anterior end ; and where it joins the 

 hind-gut or proctodaeum, a number of excretory mal- 

 pighian tubules are given off. The hind-gut has three parts : 

 a short and narrow ileum, a longer and wider colon, and 

 & short rectum ending at the anus. 



A pair of branched salivary glands and a salivary reser- 

 voir lie along each side of the crop ; their ducts unite to 

 form a common duct which opens into the mouth at the 

 base of the tongue or hypopharynx. Digestion takes 

 place in the crop ; the secretion from the hepatic caeca 

 passes forward into it. The mid-gut is the absorptive area. 



Briefly describe the Respiratory and Circulatory Systems of 

 the Cockroach. 



There is a ramifying system of branching air-tubes or 

 tracheae throughout the body and wings. These tubes 

 have a silvery appearance, and their cuticular lining has 

 a spiral thickening which renders them elastic and keeps 

 the lumen of the tube open. The air is taken in through 

 the ten pairs of lateral openings or stigmata, and it is ex- 

 pelled when the body muscles contract and compress the 

 tracheae. 



The heart is a chambered tube situated beneath the skin 

 along the middle line of the body. Each chamber has a 

 pair of ostia, through which the blood passes from the 

 surrounding pericardium. The heart drives the blood 



