380 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53. 



DESCRIPTION OF PLATE 23 



PAGE 



NcTodia iveeksi, new genus and new species (See pi. 44) 257 



Fig. I. A large specimen of the dorsal shield preserving nearly the en- 

 tire thorax and a portion of the cephalon. The cephalon has 

 been restored in outline from specimens represented by figs. 

 2 and 3. Two-thirds natural size. U. S. National Museum, 

 Catalogue No. 567920. 



2. A nearly perfect individual showing fifteen thoracic segments 



in the anterior portion of the thorax and eleven in the poste- 

 rior portion. Natural size. U. S. National Museum, Cata- 

 logue No. 56792^. 



The difference between the posterior portion and anterior 

 portion of the thoracic segments is also shown by fig. 4. 



3. A specimen that has been slightly distorted by compression, 



showing the cephalon and a few thoracic segments. Natural 

 size. U. S. National Museum, Catalogue No. 56792c. 



4. Posterior portion of the thora.x. This shows five segments of 



the anterior portion and ten segments of the posterior por- 

 tion of the thorax. Natural size. U. S. National Museum, 

 Catalogue No. 56792^. 



5. Cephalon and portion of the thorax. X 4- This represents 



the smallest specimen found of this species. U. S. National 

 Museum, Catalogue No. 56792^. 



6. Enlargement of the lateral cheeks of a cephalon between the 



eye and the outer anterior and posterior borders. This illus- 

 trates very perfectly the venation extending outward from 

 the base of the eye lobe. X 2. U. S. National Museum, Cata- 

 logue No. 56792/^. 



7. Portion of a thoracic segment illustrating the central axis, 



the pleural lobes and extension. Natural size. U. S. National 

 Museum, Catalogue No. 56792^. 



8. Pygidium (X 2) that is associated with specimens of this species 



and Holmia rotvei [pi. 29]. U. S. National Museum, Catalogue 

 No. 56792/1. 



The specimens represented by figs. 1-8 are from locality (if), 

 16 miles south of Silver Peak, Nevada. 



