258 OILMAN A. DREW. 



PLATE XXIII. 



Fig. n. Etching made from a photograph of the margin of Fig. I, before that 

 figure had been completed. It will be noticed that the same margin occurs on all of 

 the figures that show this portion of the mantle. 



Fig. 12. Etching made from a photograph of a combination of a photograph and an 

 ink drawing. The photograph was made from Fig. 2 before the alimentary canal 

 had been worked in. Fig. 2 was drawn on a print like Fig. II. Figs. 3, 4 and 6 

 are etchings of drawings made by adding various organs on prints like Fig. 12. 



