EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 75 



limestone being of different character and the genus not being well known 

 in equivalent horizons of the New York province. 



Localities. Moosehead lake, Baker Brook point ; Matagamon lake, 

 east side, i mile above dam. 



Prosocoelus pes-anseris Zeiler & Wirtgen var. occidentalis Clarke 



Plate 16, figures 14, 15 



Prosocoelus pes-anseris Zeiler & Wirtgen var. occidentalis Clarke. N. Y. 

 State Mas. Bui. 107. 1907. p. 223 



The genus Prosocoelus was established by Keferstein in 1857 and was 

 first applied to the species Grammysia pes-anseris Zeiler & Wirt- 

 gen ' by Beushausen 2 and the latter author subsequently described several 

 species from Coblentzian horizons. The hinge in the genus is characterized 

 by its strong and large, curved, umbonal teeth, two in number, with the 

 uppermost the larger, and in the left valve a small triangular anterior tooth ; 

 a broad ligament area with longitudinal groove. The exterior bears two or 

 three strong divergent ridges. In P. pes-anseris these surface ridges 

 have an extreme of development. 



It is of extraordinary interest to find this genus, not before known out- 

 side the typical regions of the Coblentzian, present in the fauna of central 

 Maine and by a species which bears so strong a resemblance to P. pes- 

 anseris as to make comparison therewith more reasonable than with any 

 other of the known forms. 



The shells from this fauna are usually elongate, broader behind than in 

 front, nearly twice as long as high, with two strongly defined radial ridges ; 

 the umbonal ridge separated from the median ridge by a moderately deep 

 broadening groove and in front of this a depression bounded by a still 

 lower sometimes quite vague elevation. Some of Beushausen's species of 

 Prosocoelus, especially P. ellipticus (Schalke, Hartz) have much the 

 outline and expression of this shell. There are specimens in our collections 

 that indicate a more orbicular outline quite similar to that of P . o r b i c u- 



laris Beushausen. 3 Though one of these is figured fpl." 16, fie. i VI, I 



i i -111 11 



am not altogether certain whether these represent the latter species or may 



be compressed specimens of the former. The evidence seems to favor the 

 former view. 



Locality. Tomhegan point, Moosehead lake, Me. 



'Singhofen. Jahrb. des Vereins fur Naturkunde im Herzogthum Nassau. 1851. p. 290. 

 "Beitr. zur. Kenntn. d. Oberharzer Spiriferensandsteins. 1884. p. 109. 

 p.i 10, pi. 5, fig. 8. 



