158 SPIIMER AND GRABAU — HAMILTON GROUP OF THEDFORD 



surfaces covered with minute shells of Styliolina fissurella, and Primi- 



tiopsis punctulifera. Chonetes, and other brachiopods also occur 1£ feet 



This layer is also seen in Rock glen, where, near the mouth of 

 the glen, it is conspicuous above the coral layer. 



3. Coral layer, a decomposed shale full of the characteristic corals found 

 in this layer in the other localities. Spirifer mucronatus var. thed- 

 fordensis is also common 3^ feet 



2. Encrinal limestone, the lowest bed of 4 inches is separated from the 



upper part by a 6-inch bed of black shale (26) 2 feet 



1. Blue shale, poor in fossils except near the base 30+ feet 



About 25 feet below the Encrinal limestone occurs a thin layer of 

 limestone (la) made up of fragments of crinoid stems and full of shells of 

 a large variety of Tentacidites attenuatus, and containing, not infrequently, 

 heads and plates of Arthroacantha punctobrachiata, as well as shells of 

 Platyceras arkonense. The latter is often a common form, and not infre- 

 quently retains its long spines. This limestone layer is seldom over an 

 inch or two in thickness. Other thin beds occurring in the lower 10 

 feet of the shale are made up of the shells of Spirifer mucronatus var. 

 arkonensis, and not infrequently contain Tentaculites attenuatus and other 

 fossils. 



The following fossils were found in bed number 4 : 



4. Cryphseus boothi Green. 41. Pterinea flabella (Conrad). 



8. Primitiopsis punctulifera Hall. 71. Chonetes lepida Hall. 



19. Tentacidites attenuatus Hall (var.). 74. Chonetes scihda Hall. 



20. T. cf. gracilistriatus Hall. 113. Amboccelia umbonata (Conrad). 



21. Styliolina fissurella Hall. Crinoid joints. 



The following species were found in the coral layer (bed 3) of Sec- 

 tion E : 



3. Phacops rana Green. 79. P. penelope (Hall). 



4. Cryphseus boothi Green. 84. Camarotcechia thedfordensis Whit- 

 8. Primitiopsis punctulifera Hall. eaves. 



27. Platyceras arkonense S. and G., ex- 87. Leiorhynchus laura (Bill.). 



treme old age form. 97. Atrypa reticularis (Linn.). 



28. Platyceras subspinosum Hall. 103. Spirifer mucronatus (transition 



30. Platyceras quinquesinuatum Whit- forms). 



eaves. 111. Cyrtina hamiltonensisHsiW. 



31. Orthonychia conicum (Hall). 116. Rhynchospir a eugenia (Bill.). 

 41. Pterinea flabella (Conrad). 126. Intrapora elegantula (Hall). 



64. Pholidostrophia iowaensis (Owen). 162. Botryllopora socialis Nicholson. 



65. Leptostrophia perplana (Conrad). 163. Hederella canadensis (Nich.). 

 75. Chonetes vicinus (Castleneau). 165. H. fili for mis (Nich.). 



78. Productella cf. productoides (Mur- 186. Nucleocrinus elegans (Conrad). 



chison). 209. Trachypora elegantula Bill. 



79. Khipidomella sp. 211. Cladopora cf. fischeri (Bill.). 



