Pirsson and Schuchert — OrisJcany Formation. 223 



andesine-labradorite. They are also filled with infiltrated 

 chloritic substance. The iron ore is changed to leucoxene and 

 the apatite and micrographic intergrowths are the only 

 unchanged constituents. The rock finally weathers with a 

 brown crust of limonitic material. The mass is a large one 

 and must be a prominent factor in the structure of the local 

 geology. 



The fossils collected by Mr. and Mrs. Pirsson on Pari in Stream 

 are from the Moose River sandstone, one of the Oriskanian 

 formations. The first good geologic account of this region 

 dates back to 1861, when Charles H. Hitchcock determined 

 the Oriskany sandstone here. In 1889, Van Ingen collected 

 fossils along Parlin Stream for H. S. Williams, and in 1905 

 O. O. Ny lander gathered other material for John M. Clarke. 

 The latter has brought together all that is known about the 

 Oriskanian of this area in his work, " Early Devonic History 

 of New York and Eastern North America" (Mem. 9, N. Y. 

 State Mus., 1909, pp. 52-90, pis. 12-21). 



Below is given an annotated list of the Oriskanian fossils 

 from Parlin Stream, just below the old dam above the falls, 

 Somerset County, Maine, collected by Mr. and Mrs. Pirsson. 



Beachiopoda. 



Pholidops terminalis Hall. Two specimens. 

 Dahnantlla drevermanni Clarke ? Two small specimens. 

 Chonostrophia dawsoni (Billings). One large and two young 



specimens. 

 Leptocodia flabellites (Conrad). Common. 

 fSpirifer pirssonoz, n. sp. 



Clarke did not name this form, but has it from Telos 

 Lake dam, and Moosehead Lake, 7 miles north of Kineo. 

 He states that the form is common and that he thinks 

 it "will prove unlike any known to us." The interior 

 resembles very much the common Oriskanian guide 

 species, S. ?niirchisoni, but as all of the specimens are 

 mature, never attain to one-half the size of S. murchi- 

 soni, and have a smaller number of plications, it is 

 here proposed to name the new form S. pirssonce, after 

 Mrs. Pirsson, who collected and presented to the Pea- 

 body Museum of Yale University an abundance of nat- 

 ural moulds. Further, the six plications on each side 

 of the fold and sinus never attain the prominence or 

 angularity of those in <8. murchisoni. The species is 

 based on the cotypes figured by Clarke in the work cited 

 on Plate 20, Figures 9-12. 



Spirifer, n. sp. 



This common species gives the impression of being 



