158 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



posterior intermediate cardiac bar is attached to the lower side of 

 the lateral tooth at a point about one-third of its length from the 

 anterior end. 



The separation of the cardiac and pyloric plates necessitates a 

 downward, inward, and upward swing of the anterior upper angle of 

 the lateral tooth which carries the anterior end of the grinding surface 

 of that tooth toward the median line. At the same time the con- 

 traction of the postero-lateral gastric muscles pulls the posterior 

 end of the lateral tooth outward and upward, and the tooth, rotating 

 on the line between its articulations with the upper end of the anterior 

 dorso-lateral pyloric plate and with the posterior intermediate cardiac 

 plate, drives its anterior cusps inward with considerable force. When 

 the gastric muscles relax the elasticity of the structures, coupled 

 with the pull of the cardio-pyloric muscles, draws the median tooth 

 backward and the lateral teeth outward. 



Returning to the enumeration of the ossicles of the stomach we 

 find on its sides the following: 



8. The gastrolithic bar. This is a sigmoid bar whose upturned 

 posterior end articulates with the pterocardiac ossicle, the anterior 

 end of the lateral tooth, and the bar to be described next. Its 

 anterior end follows for a short distance the upper edge of the gastro- 

 lithic plate, which is a triangularly ovate epithelial plate that during 

 the latter part of the period between molts secretes a thick plate of 

 lime, the gastrolith (see page 172). 



9. The accessory lateral cardiac ossicle or upper intermediate 

 cardiac bar extends with a gentle curve backward and then down- 

 ward from between the preceding bar and the pterocardiac bar to : 



10. The inf ero-lateral tooth, which is an irregular plate with three 

 acute cusps upon its anterior edge. 



11. The lower intermediate cardiac bar. This extends back- 

 ward from the preceding tooth to : 



12. The upper ventro-lateral cardiac bar, which passes forward 

 along the ventral side of the cardiac sac to the cesophagus where it 

 bears upon its upper side : 



