282 



THE ANATOMY OF INVERTEBRATED ANIMALS. 



attached by six ligaments, corresponding with the alge of the 

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



11 \ ' n 



\ b ijff I* 



f 



Fio. 74.— Astacus, Longitudinal Section.— I, II, III, Sterna of first, second, and third 

 somites; oe, oesophagus; lb, labrum : I. metastoma ; 6-, 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 ; m*. insertion of posterior gastric muscles; pc, procephalic processes; 

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

 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 





