332 PALAEONTOLOGY OF NEW YORK. 



Dr. Waagen has taken Norwood and Pratten's species, Produc.tus splendem, 

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

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

 long for the greater part io 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. Lasallmsis, 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 bifui'cated 

 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 change the name of this species to P. Mallana (Monograph U. S. Geol. 

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

 dently a Proddotella. Should, however, the American species be referred to Marginipera, its original 

 designation may be retained. 



