310 NEW YORK STATE MUSEUM 



PLATE 26 

 Fig. 



1 Showing the same stage as represented by figures, 20, 21 in 



plate 25. The podocyst in this stage reaches its greatest 

 size, and in the succeeding stages rapidly diminishes in 

 size, X 14. 



2 Ventral view of an embryo of the same stage as repre- 



sented in figure 1; showing the base of foot, tentacles, 

 mouth, lateral lips and corrugations surrounding the 

 mouth, X 25. 



3 A profile view of the same, showing the tentacles and the 



"primitive kidney" on the side of the endodermal mass, 

 x30. 



4 A more advanced stage, x 14. 



5 A still more advanced stage. The tentacles have begun to 



assume their adult form; the internal organs are assum- 

 ing definite form; and the endodermal mass and podocyst 

 are greatly reduced in size by absorption, x 14. 



PLATE 27 

 Fio. 



1 Showing the position of the embryo within the egg just be- 



fore emerging, x 8. 



2 The same removed from the egg, x 16. 



3 A fully developed specimen. The integument is cut along 



the dorsal line and drawn back, so as to show the internal 

 organs. See plate 15 for a description of the various or- 

 gans. 



4 An egg containing two embryos, x 8. 



5 An egg containing four embryos, x 8. 



6 The tentacles and protruded mouth of an embryo; ut su- 



perior tentacle; It lower tentacle; tni buccal mass; dp jaw 

 TO retractor muscle of jaw, x 10. 



7-9 Abnormal eggs. These are of frequent occurrence, x 4. 



