SNYDER CREEK SHALE. 43 



Crinoidea. — Crinoid remains are very rare. The species of 

 Melocrinus are all distinctive, but they have been found in only 

 one locality. No crinoid heads have been collected from the 

 Callaway though the stems are abundant. Melocrinus may be 

 present in the Callaway, though the stems and fragments sug- 

 gest Megistrocrinus or Dolatocrinus. Melocrinus gregeri Rowley 

 occurs in the Iowa Devonian and a thorough study of the crinoids 

 from Iowa may show the presence of other Snyder Creek species. 



Vermes. — Spirorbis omphaloides (Goldfuss) is the only worm 

 identified in the faunas. It is found from bottom to top of the 

 formation but is not abundant. 



Bryo7oa. — Lioclema occidens Hall and Whitfield is very 

 abundant in one member in the lowest ten feet and ranges to 

 the top of the formation. Rhombopora missouriensis Branson 

 largely makes up one thin bed of limestone in the lowest ten 

 feet of the formation. 



Brachiopoda. — The brachiopod. species are the most im- 

 portant in the faunas. Twenty-seven species have been identi- 

 fied. Stropheodonta is the most important genus. Stropheodonta 

 demissa (Conrad) is present in the Mineola and Callaway and 

 in the Snyder Creek it changes very rapidly, giving rise to six 

 other species within ten feet of the bottom. The new species 

 are abundant in 10 to 15 feet of strata, then dwindle in 10 to 

 15 feet of strata, and seem to be absent from the highest 20 

 feet. The variations are in the direction of longer hinge-line 

 and shorter hinge-line; coarser plications and finer plications; 

 great convexity and flatness; narrow umbo and broad umbo. 

 Specimens are very abundant and show all phases of the varia- 

 tions. 



After the stropheodonts Spirifer euryteines Owen is the 

 most characteristic brachiopod. Near the top at the Cow Creek 

 locality it is very abundant. Schizophoria striatula (Schlotheim) 

 is as abundant as Spirifer euruteines Owen, but its wide distribu- 

 tion in other formations makes it less characteristic. Cyrtina 

 triquetra Hall is common at the New Bloomfield locality in the 

 bottom member but is rare in other places. Spirifer annae Hall 

 is common in the same member as C. triquetra Hall. Athyris 

 fultonensis Hall is common in many localities and abundant in 

 some. Atrypa reticularis (Linnaeus) is one of the most abundant 

 forms and has many varieties. Spirifer asper Hall is listed on 

 the authority of D. K. Greger. 1 



^m. Jour. Sci., vol. 27, p. 376. 



