FIG. 7 



Plate VI. 



Fig. 7.-^Gastrolith of a fourth-stage lobster, five days after the molt, .x 20. 



Fig. 8. — Gastrolith of a fourth-stage lobster eight days after the molt. 



Fig. 9. — Section through the gastrolithic plate of a fourth-stage lobster killed a short time before the molt to 

 the fifth stage, x 260. 



Fig. 10. — Section through the base of the cardiac portion of the stomach of an adult lobster, a short rUstance in 

 front of the cardio-pyloric valve, x 6. 



