20 Natural History Bulletin. 



and the beds from which it was obtained are referred to the 

 age of the Hamilton group of New York. Notwithstanding 

 the unmistakable specific identity of Hall's specimen with that 

 illustrated by Owen in his report of 1852, Plate III, Fig. 6, 6 

 a-b, there is no reference to the fact that the species has 

 ever appeared before in geological literature. Indeed Hall 

 seems to have regarded Owen's figures as illustrating a typi- 

 cal form of S. eiirtiteines, and later, Pal. N. Y., Vol. IV, p. 

 210, he expresses the belief that they may have been made 

 from Ohio or Indiana specimens. 



The description and figures of S. pa7'ryana are found in 

 Hall's report on, page 509, Plate IV, Fig. 8 a. b. In the same 

 report, on page 520, Plate VII, Fig. 7 a-d, another specimen 

 of the same species, the specimen being preserved as an in- 

 ternal cast in sandstone, is described as a new species and 

 called S-pirifcr cafax. The sandstone whence the S. capax 

 form was obtained, although belonging essentially to the same 

 geological horizon as the limestone near Buffalo, is referred 

 to the age of the Chemung group of New York. Owen, in 

 1852, had figured one of the sandstone casts — Plate III, Fig. 

 2, 2 a. — as part of his illustration of S. curutcincs, and the 

 identity of S. capax. Hall, with the form so figured, is appro- 

 priately noted in connection with Hall's description. 



Owen recognized the fact that the forms of the spirifer 

 under consideration in both limestone and sandstone are 

 specifically the same and that they belong essentially to the 

 same geological horizon. He identified both, however, with 

 the very distinct species Sfirifera enriiteincs. Hall recog- 

 nized the fact that these forms were distinct from 6". eiiruteines, 

 Owen, 1839-1844, but he made the mistake of separating 

 them one from the other as distinct species and referring them 

 to distinct geological horizons. 



As shown in the preceding paper, S. farryana, Hall, has 

 precedence over S. cajyax, and must embrace the forms 

 originally referred to the last named species. 



In the Geological reports of Illinois, Vol. Ill, p. 433, Plate 



