PLATE IV. 

 (All the figures are of the natural size.) 



Fig. 1. — Geratiocaris Murchisoni (Agassiz). The three caudal spines. Oxford 

 Mus. (Page 18.) 



Fig. 2. — G. gigas, Salter. Ultimate segment and the appendages, not quite 

 perfect. Oxford Mus. (Page 25.) 



Fig. 3 — G. Murchisoni (Agassiz). The three appendages, not quite perfect. 

 Oxford Mus. (Page 19.) 



Fig. 4. — G. tyrannus, Salter. Seven segments, and fragments of the appen- 

 dages. Oxford Mus. (Page 23.) 



Fig. 5. — G. Halliana {?), T. R. J. & H. W. Very small. Carapace and two 

 segments. Oxford Mus. (Page 29.) 



Fig. 6. — The same (?). T. R. J. & H. W. Very small. Carapace and six 

 segments. Oxford Mus. (Page 29.) 



Fig. 7. — G. cassioides, T. R. J. & H. W. Carapace, four segments, and telson. 

 Oxford Mus. (Page 60.) 



