282 



THE ANATOMY OF INVERTEBRATED ANIMALS. 



attached by six ligaments, corresponding with the alse of the 

 heart in insects, but not, like them, muscular. Except by 



ffjl / / 77 



If / I < / * 'J hO 



Fig. 74.— Astacus, Longitudinal Section.— I, II, III, Sterna of flret, second, and third 

 somites; ce, oesophagus ; lb, labrum : I, metastoma ; G, membranous part of the 

 stomach; c, cardiac ossicle ; pt. pterocardiac ; uc, urocardiac ; cl, lateral cardiac; 

 p, cardio-pyloric valve ; pi, inferior pyloric valvular apparatus ; m, anterior gastric 

 muscle ; ni*, insertion of posterior gastric muscles ; pc, procephalic processes ; 

 h', opening of hepatic duct ; v, pyloric caecum ; i, k, intestine ; gn, testis ; gn', giv , 

 vas deferens ; C, heart ; ao, ophthalmic artery ; aa, antennary ; ah, hepatic ; as, 

 sternal ; ap, superior abdominal artery ; b, cerebral ganglia ; sg, azygos visceral 

 nerve. 



these ligaments, and by the arteries, which pass through it, 

 the walls of the pericardial cavity, or blood sinus (for such it 



