332 PALEONTOLOGY OF NEW YORK. 



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

 as the type of the group which embraces his typical species, and fitrther 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, Productus splendens, Norwood and Pratten, P. longispiiius, Sow- 

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

 some stage of development. 



In the species Productus 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 Productos 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 pi-oposed to change the name of this species to P. Hallana (Monograph U. S. GeoL 

 Sm-v., voL viii, p. 130, 1SS4), as de Koninck had used the same term for a Devonian species which is evi- 

 dently a Proddctslla. Should, however, the American species be referred to MARGiSfiPBRA, its original 

 designation may be retained. 



