PLATE I. 



Fig. 



1. The anatomy of Terebratula flavescens, exposed by the removal of the right moieties of 



the valves, pallial lobes, and bent portions of the fringed arms. Magnified 

 4 diameters. 



2. A dissection of the Terehratula flavescens, shovring the muscular system, peduncle, 



and calcareous loop. The valves have been divaricated at the hinge. Magnified 

 6 diameters. 



3. The visceral mass and cavity exposed in the cardinal part of the perforated valve of 



the Terehratula flavescens. Magnified 6 diameters. 



4. The alimentary canal laid open, and part of the liver of the Terehratula flavescens. 



Magnified 20 diameters. 



5. The anatomy of Lingula anatina, exposed by the removal of the valve and pallial 



lobe answering to the ventral ones in Terehratula, and principally to show the 

 auricles, ], i, and the intestinal sinus, 8. Magnified 3 diameters. 



6. The alimentary canal, liver, and intestinal venous sinus of Lingula anatina. 



Magnified 12 diameters. 



7. Five embryos, removed from the ovarian cavity in the pallial sinus of Lingula 



anatina. Magnified 120 diameters. 



