332 PALEONTOLOGY OF NEW YORK. 



Dr. Waagen has taken Norwood and Pratten's species, Produdus splendens, 

 as the type of the group which embraces his typical species, and further has 

 expressed the opinion that the American species from the Coal Measures be- 

 long for the greater part to Marginifera. It is extremely doubtful if the 

 evidence will sustain this assumption though there are certain species of the 

 Coal Measures, Produdus splendens, Norwood and Pratten, P. longispinus, Sow- 

 erby, P. Lasallensis, Worthen, which show the characters of Marginifera in 

 some stage of development. 



In the species Produdus dissimilis, Hall,* from the middle Devonian of 

 Rockford, Iowa, and the upper Devonian of New York, similar internal char- 

 acters are quite strongly developed, especially in the pedicle-valve, and in both 

 valves the margins of the ridges are more or less distinctly crenulated. While 

 the species has the cardinal area, teeth and sockets in an exceedingly obscure 

 condition, the cardinal process is like that of Productella, strongly bifurcated 

 to its base, and its external surface presents characters rarely met with either 

 in Productus or Productella, but not uncommon in Strophalosia ; a spinifer- 

 ous pedicle-valve, and a brachial valve without spines, but covered with con- 

 centric lamellose ridges. 



* Mr. Walcott has proposed to chang-e the name of this species to P. Hallana (Monograph U. S. Geol. 

 Snrv., vol. viii, p. 130, 1884), as de Koninck had used the same term for a Devonian species which is evi- 

 dently a PaoDUOTELLA.. Should, however, the American species be referred to Maeginifbra, its original 

 designation may be retained. 



