Report of the State Geologist, 235 



Syringothyris extenuata. Hall's sp. 



Spirifer extemiatus, Hall, 1858. Geol. Surv., Iowa, part 2, p. 520, pi. 7, 

 fig. 6. 



Spirifer extenuatus, White, 1875. Geog. & Geol. Expl. & Surv., west 100 

 Merid., p. 88, pi. 5, fig. 9. 



Syrinfjothyris halli, A. Winchell, 1863. Proc. Acad. Nat. Sci., Phil., 

 vol. 15, p. 8. 



This species is separated from S. carteri by its smaller size, different 

 pi'oportions and by the hinge extremities being pointed, not rounded, 

 as in that species. The sinus is also more defined and deeper. 



Dr. C. A. White, in the work above cited, sa^^s: 



" So far as external characters are concerned, no specific difference 

 can be detected between our shell [S. extenuata] and Syringothyris 

 Halli, Winchell. His type specimens were obtained from strata of the 

 Kinderhook formation at Burlington, Iowa, and Clarksville, Mo. 

 Those of Prof. Hall were obtained from the same strata at the 

 first-named locality. The want of material difference between the 

 dorsal valve of Prof. Hall's species (the only part of the shell 

 described and figured by him) and the corresponding part of Prof. 

 Winchell's specimens, together with the fact that they are associated 

 in the same strata at one of the typical localities, leaves little cause 

 for doubting the specific identity of Syringothyris Halli and Spirifer 

 extenuatus." 



I believe a larger series of specimens than I possess would show 

 this species to be a young stage of S. carteri. S. typa, S. halli and 

 S. extenuata have all been described from material derived from the 

 Kinderhook group at Burlington, Iowa. On the other hand, in Nevada 

 S. carteri and S. extenuata are never found associated at the same 

 locality. 



Distribution. — Lower Carboniferous: In the Kinderhook group at 

 Burlington, Iowa; Battle Creek, Michigan; Clarksville, Missouri, 

 and Mountain Spriug, Old Mormon road, Nevada. Waverly sandstone 

 of Licking county, Ohio. 



Syringothyris gigas. Troost's sp. 



Cyrtia gigas, Troost, 1841. Sixth Geological Report, Tennessee, p. 12. 



I can add nothing farther to the original description of Prof. 

 Troost, than that its relations are closer to S. carteri than to S. texta. 

 The original description reads as follows : " I noticed this fossil in my 

 last report under the name of Spirifer cuspidatus, Sowerby, because it 

 resembles, more or less, the figure of that fossil in the Manual of De 



