l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8o 



EXPLANATION OF PLATES 



P^-^T-^ ' PAGE 



Lar.tif track-covered slab (No. 11,707. U. S. N. M.) from the Hermit shale, 

 showing trackways of Panibaropus coloradcnsis (Lull) (large 

 track forming the diagonal trail across left side of slab) ; Col- 

 lettosaunis /^///(/rfrtch'/".? Gilmore (trail with distinct tail drag 

 to right of center) : and Hylopus hcnnilamis Gilmore (all other 

 tracks on the slab). This slab has a greatest transverse diameter 

 of 6 feet and 5 inches ; a greatest vertical diameter of 3 feet and 

 10 inches 7 



Plate 2 



. liiiiiiobafrachus turbatans, new genus and species. Type. No. 11,691, 

 U. S. N. M. Trackway from the Supai formation. Bright Angel 

 Trail, Grand Canyon National Park, Arizona, .\1iout one-half 

 natural size S 



Plats 3 



F'iG. I. Hyloidichnus ichitci. new species. Type. No. 11,69^. U. S. N. M. 



About natural size 5 



Fig. 2. Unidentified tracks (invertebrate) from the Supai formation, 

 O'Neill Butte, Grand Canyon National Park, Arizona. About 

 natural size 12 



Plate 4 



Fig. I. Unidentified trail (invertebrate). No. 11,740, U. S. N. M. From 

 the Supai formation on west side of O'Neill Butte, Grand Canyon 

 National Park. Arizona. About one-half natural size 10 



Fk;. 2. Unidentified trail (invertebrate). No. 11.693, U. S. N. \l. From 

 the Supai formation ( upper track-bearing horizon ) , on west side 

 of O'Neill Butte, (irand Canyon National Park, Arizona. More 

 tlian (ine-lialf natnral size ij 



Plate 5 



Trilol)ite tracks and trails. All from the Tapcats sandstone, Middle Cam- 

 brian, as exposed in the Bright Angel section, (irand Canyon 

 National Park, Arizona. Figs, i, 2, and 4. about three-fourths 

 natural size. Fig. 3, natural size 14 



