662 GEOLOaiCAL SURVEY OF THE TERRITORIES. 



EXPLANATION OF PLATE XXIV. 



Fig. 1. JSatheria helfragei, edge of carapace, greatly enlarged, X « Tolles, A. ocular 



Fig. 2. Ustheria joneeii, edge of sbell, with a portion chipped off, X i A. 



Fig. 3. Eatheria mexicana, Ohio, X i A. 



Fig. 4. Estheria daweoni (fossil). Drawn by L. Tiouvelot. 



Fig. 4a. Estheria daivsoni, showing the granulated ridges, X i A. 



Fig. 4b. Estheria dawsoni, showing the pits between the ridges. 



Fig. 5. Estheria californica, X i A. 



Fig. 6. Estheria mexicana, Kansas, X i A. 



Fig. 7. Estheria morsei, Iowa ; edge of the shell. 



Fig. 8. Estheria compleximanus, Kansas; edge of shell, x 225 diameter. 



Fig. 9. Estheria mexicana, section through the entire animal, through the front part 

 of thorax; ant^, antennae ; an/*, base of second antennae ; shg, section through 

 the shell-gland ; ir', upper, ir", lower division of the flabellum ; int, intes- 

 tine ; ng, nerve-ganglion ; 1-6, first to sixth endites. 



Fig. 10. Estheria compleximanus. Section through the posterior part of the thorax, 

 the shell having been removed ; lettering as in Fig. 9 ; wms, dorsal mus- 

 cles. 

 All the figures, except Fig. 4 drawn by the author. 



