CAMBRIAN BRACHIOPODA — WALCOTT II7 



DESCRIPTION OF PLATE 7 



f. = flexure line of area. /. = anterior lateral muscle scar. 



h. = central muscle scar. k. = middle lateral muscle scar. 



i. =transmedian muscle scar. /. = outside lateral muscle scar. 



Page 



Mickivitzia occidcns, new species 54 



Fig. I. View of the type specimen from Lower Cambrian shale, 

 northeast of Silver Peak Mill, Silver Peak quadrangle, 

 Esmeralda County, Nevada, showing the outer and inner 

 surface of the outer laj'er. U. S. National Museum Cata- 

 logue No. 51518. 



Mickwitsia prctiosa, new species 54 



Fig. 2. Top view of the type specimen from the Lower Cambrian 

 Eophyton sandstones at Lugnas, Vestergotland, Sweden. 

 U. S. National Museum Catalogue No. 51523. 



Micromitra haydcni, new species 55 



Fig. 3. Top view of type specimen of ventral valve. U. S. National 

 Museum Catalogue No. 51437a. 

 2a. Posterior view of ventral valve.- U. S. National Museum 

 Catalogue No. 51437&. 



The specimens represented by Figs. 3 and 3a' are from 

 the Middle Cambrian limestones of the Langston forma- 

 tion in Two Mile Canyon, southeast of Malad, Oneida 

 County, Idaho. 



Micromitra (Iphidella) Ionise, new species 56 



Fig. 4. Top view of type specimen of ventral valve from the Lower 

 Cambrian shales of the Lake Louise formation, at Lake 

 Louise, south of Laggan, Alberta. V. S. National Mu- 

 seum Catalogue No. 51401a. 

 4a. Side view of associated ventral valve. U. S. National Mu- 

 seum Catalogue No. 51401&. 



Micromitra (Iphidella) nyssa, new species 57 



Fig. 5. Top view of type specimen of ventral valve from Middle 

 Cambrian shales between Gordon Mountain and Cardinal 

 Peak, Ovando quadrangle, Powell County, Montana. LI. S. 

 National Museum Catalogue No. 51441a. 



Micromitra (Paterina) ti'a/'/a, new species 59 



Fig. 6. Top view of type specimen of ventral valve from a drift 

 block of Lower Cambrian shale, slope of Mt. Bosworth, 

 British Columbia. U. S. National Museum Catalogue No. 

 51402a. 



Micromitra (Paterina) zvilliardi, new species 60 



Fig. 7. Top view cf type specimen of ventral valve from the Lower 

 Cambrian Montevallo shale, .25 mile (.40 km.) northeast 

 of Helena, Shelby County, Alabama. U. S. National Mu- 

 seum Catalogue No. 51482a. 



