NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 





DESCRIPTION OF PLATE 2 



PAGE 



Mesonacis insolcns, new species 8 



Fig. I. Poorly preserved carapace giving some idea of the shape and 

 general characteristics of the species. Cotype. U. S. Nat. Mus., 

 Cat. No. 78386. 



2. Well preserved cephalon beside the hypostoma of Mesonacis frc- 



monti. Cotype. U. S. Nat. Mus., Cat. No. 78387. 



3. Small cephalon illustrating the size and position of the eyes and 



the glabella. Note the occipital spine. Cotype. U. S. Nat. Mus., 

 Cat. No. 78388. 



4. A larger head in which the full size of the advanced genal spines 



is shown. Cotype. U. S. Nat. Mus., Cat. No. 78389. 



Mesonacis hristolensis, new species 7 



Figs. 5, 6. Cephalon and enlarged ( X 4) view of the glabella showing 

 the surface features. Cotype. U. S. Nat. Mus., Cat. No. 78390. 



7. Another cephalon with a fairly complete glabella. Cotype. U. S. 



Nat. Mus., Cat. No. 78391. 



8. Fairly complete cephala of this species and of M. insolens, show- 



ing the different angles at which the genal spines arise. Cotype. 

 U. S. Nat. Mus., Cat. No. 78392. 



Mesonacis fremonti (Walcott ) 6 



Fig. 9. Portion of the thorax near the posterior end. Plesiotype. U. S. 

 Nat. Mus., Cat. No. 78385. 



