22 AMERICAN JOURNAL 



Fig. 5. Muscular impressions on the shell, nat. size, a, cica- 

 trix of the mantle. 5, 5, horse-shoe-shaped muscle cicatrix, d, 

 sinus. (Drawn as if seen from above.) 



Fig. 6. Animal, nat. size, as moving. 



Fig. 7. a, anterior rhachidian teeth. 5, the same near the 

 middle of the radula. c, side figure of 6th lateral, d, do. of 

 75th lateral. 



Fig. 8. Section of the rectum. 



Fig. 9. Side view of alimentary canal. 



References to Plate 4. 

 Fig. 1. Side view of normal specimen of (r. reticulata, Sby. 

 Fig. 2. Same from below. 

 Fig. 3. Curious variety of the same. 

 Fig. ] 2. G-adinia carinata, Dall, from above, nat. size. 

 Fig. 13. Same from below. 



