REPORT OF COMMISSIONERS OF INLAND FISHERIES. 159 



13. The antero-lateral cardiac bar. This bar extends obliquely 

 upward and forward almost to the antero-ventral angle of the 

 gastrolith. 



The posterior lateral dilator muscle arises from the posterolateral 

 angle of the mandibular sternum, extends upward, inward, and back- 

 ward to its insertion upon the antero-lateral cardiac bar. 



14. Immediately below the upper ventro-lateral cardiac bar lies 

 the lower ventro-lateral cardiac bar, which has much the same shape 

 as that bar 'but extends farther backward. The posterior ends of 

 these two bars are hinged upon one another so that they open and 

 shut like a pair of pincers. 



15. The ventral cardiac plate. This is a small oval median plate 

 lying between the posterior ends of the lower ventro-lateral cardiac 

 bars. 



16. The posterior intermediate cardiac bar passes obliquely 

 upward and forward from the posterior end of the lower ventro- 

 lateral cardiac bar to the lateral tooth. 



The lower lateral cardiac constrictor muscle extends upward and 

 forward from the entire upper edge of the lower ventro-lateral cardiac 

 bar to a slight thickening of the stomach wall which lies midway 

 between the gastrolith and the lower ventro-lateral cardiac bar. 

 The contraction of this muscle draws together the two edges of a 

 fold of the stomach wall and thus causes the fold to project farther 

 into the lumen of stomach. 



The ventral cardiac constrictor extends between the right and left 

 lower ventro-lateral cardiac bars. 



The cardiac sac is irregularly ovate. Its greatest width lies 

 between the pterocardiac ossicles and its smaller end opens into 

 the pyloric sac. Its dorsal surface follows the curvature of the 

 adjacent carapace and its anterior surface is uniformly convex 

 when distended. The somewhat flattened sides of the sac converge 

 below so that its ventral surface is reduced to a narrow band between 

 the ventro-lateral cardiac bars and a larger area in front of the 

 oesophagus. 



