REPORT OF COMMISSIONERS OF INLAND FISHERIES. 171 



pyloric valve is relatively higher, it lacks the posterior lobe, and it is 

 armed with long heavy bristles. 



The Stomach of the Second-Stage Lobster. (Plate IX, Fig. 15.) 



The stomach of the second-stage lobster (and of the first) lacks 

 the median, lateral, and infero-lateral teeth. In the place of the 

 first, there is a high grooved projection from the dorsal wall of the 

 stomach. This is very much like the cardio-pyloric valve, and we 

 will call it the dorsal cardio-pyloric valve. Its sharp edge bears a 

 row of long heavy serrate spines which point downward and forward. 

 The cardio-pyloric valve is high and is similarly armed. 



Between the cardio-pyloric and the dorsal cardio-pyloric valves, 

 on each side of the stomach, there is a long (partly double) row of 

 bristles like those of the cardio-pyloric valve, but directed inward 

 and backward. The postero-lateral gastric muscle is inserted upon 

 the plate of chitin which supports this row of spines. 



The pyloric sac seems to be divided into a broad upper, and a 

 lower canal. All the bristles of the sac are directed backward. 



The Stomach of the First-Stage Lobster. (Plate X, Fig. 16.) 



The stomach of the first-stage lobster is like that of the second- 

 stage lobster, except that it is more nearly tubular and that it has 

 thinner walls and fewer bristles. 



In conclusion, we wish to call attention to the following facts: 



1. That while the gastric mill of the adult is a grinding and crush- 

 ing organ, that of the first and second-stage lobsters is a tearing and 

 shredding organ. 



2. That the lower pyloric canal, the lateral pouch, and the two 

 cardiac canals remain throughout the whole metamorphosis essen- 

 tially unchanged, and that their persistence is suggestive of their 

 importance. 



