Grabau — Faunas of the Hamlton Group. 



275 



110. Spirifer audaculus, Conrad. 



1867, Hall (S. mediates), Pal. N. Y., vol. 4, p. 227, pi. 38. 



1893, J. Hall and J. M. Clarke, Pal. N. Y., vol. 8, pt. ii, p. 39. 



This species makes its first appearance in the Pleurodictyum beds, where 

 it is not infrequent. It is rare in, or absent from, the Trilobite beds, but is found 

 in some of the shales between them. It appears to be absent from the shales 

 above the Trilobite beds for a considerable height, appearing again about four 

 feet below the Encrinal limestone. It is abundant in the S. demissa bed, and 

 common in the Encrinal limestone. It occurs sparingly in the lower Moscow 

 shales, associated with 8. consobrinus. The variety Eatoni (Hall), occurs here 

 occasionally. 



111. Spirifer Augustus, Hall. 



1867, Hall, Pal. N. Y., vol. 4, p. 230, pi. 38a. 



This species is found in the S. demissa bed where it is rare. A small 

 specimen somewhat crushed, has fifteen plications on each side of the fold and 

 sinus. Another, a perfect specimen, has about twenty-five plications on each 

 side of the fold and sinus. The width of this specimen is 27 mm., its height 

 9 mm. and height of the area 7 mm. A small specimen with the area some- 

 what more arcuate may belong to this species. 



112. Spirifer macronotus, Hall. 



1867, Hall, Pal. X. Y., vol. 1, p. 231, pi. 38«. 



This species is common in the 8. demissa bed and in the Encrinal lime- 

 stone, though not as abundant as 8. audaculus, with which it is usually asso- 

 ciated. At Section C, several specimens were found one and one-half to three 

 feet below the Encrinal limestone and few were obtained from the shale 

 below the Trilobite beds at Avery's creek. Although typical specimens are 

 easily recognized wherever occuring, there are others which show a gradation 

 towards the characters of S. audaculus, the two being often indistinguishable. 

 They should probably be united. 



113. Spirifer asper, Hall. 



1858, Hall, Geol. Surv. of Iowa, vol. 1, pt. 2, p. 508, pi. 4. 



This species is fairly well represented in the 8 demissa bed. The specimens 

 rarely show more than fifteen plications on each side of the median sinus. 

 The granules are coarser in our specimens than they are represented for the 



