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 



W&J 7 



Fio. 14.—Astacus, Longitudinal Section.— I. II, III, Stern? orfirst, second, and third 

 somites; ce, oesophagus : lb. labrum : I. metastoma : 6-, membranous part of the 

 stomach; c, cardiac ossicle; at. 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', gn", 

 vas deferens ; C, heart ; qo, 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 



