SOME NEW DEVON IC FOSSILS 



223 



Prosocoelus pes-anseris Zeiler & Wirtgen var. occidentalis nov. 



The genus Prosocoelus was established by Keferstein in 1857 

 and was first applied to the species Grammysia pes-an- 

 seris Zeiler & Wirtgen^ by Beushausen^ 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 



Prosocoelus pes-anseri 



L 1 '1 ( n t a 1 i s 



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 outside 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 there- 

 with 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 



'Singhofen. Jahrb. des Vereins fur Naturkunde im Herzogthum Nassau. 1851. p. 2qo. 

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



