14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



DESCRIPTION OF PLATE 3 



PAGE 



Pacdnniias clavki, new species 9 



Fig. I. A specimen preserving the major portion of the thorax. Note 

 the narrow rim and the median ridge between it and the 

 glabella. Two other cephala occur on the same piece of rock. 

 Cotype. U. S. Nat. Mus., Cat. No. 78393. 

 2. Larger cephalon with eyes and glabella well preserved. Cotype. 

 U. S. Nat. Mus., Cat. No. 78394. 



Pacdumias ncvadcnsis (Walcott) 9 



Fig. 3. Small, but fairly complete cephalon. Plesiotype. U. S. Nat. Mus., 

 Cat. No. 78395- 



4. Large cephalon showing the intergenal spines. Plesiotype. U. S. 



Nat. Mus., Cat. No. 78396. 



5. Another large cephalon, somewhat crushed, causing this specimen 



to resemble P. clarki. Plesiotype. U. S. Nat. Mus., Cat. 

 No. 78397. 



6. Smaller cephalon with the glabella better preserved. Note the 



occipital spine. Plesiotype. U. S. Nat. Mus., Cat. No. 78398. 



7. Cephalon complete on the left side, showing position and size of 



the genal spine. Plesiotype. U. S. Nat. Mus., Cat. No. 78399. 



Mesonacis fremonti (Walcott ) 6 



Fig. 8. Enlargement ( X 4) of the left rear quadrant of the hypostoma 

 shown on plate i, figure 9. Plesiotype. U. S. Nat. Mus., Cat. 

 No. 78384. 



Dolichotnetopiis ? lodcnsis (Clark) 10 



Fig. 9. The smaller shield shows the general characters of this species. 

 The larger, less complete carapace is referred to DoUchometo- 

 pus productus. Holotype. U. S. Nat. Mus., Cat. No. 78400. 



