160 PALEONTOLOGY OF NEW YORK. 



NOTE TO PAGE 128. 



The genus Orbiculoidea of D'Orbigny was first defined and exemplified in 

 tlie Prodrome de PalL-ontologie, vol. i, p. 44, the date of this work being 1850, 

 not 1849. Dall is in error in stating that Orbicula Morrisi, Davidson, is the 

 first species mentioned under the diagnosis quoted. D'Orbigny here gives three 

 species in the following order : 0. Forbesi, Davidson, 0. Morrisi, Davidson, 0. 

 Davidsoni, D'Orbigny. As no species is specially designated as the type of 

 the genus we are compelled to assume these three as types in their order and 

 upon tlieir merits. It is shown on page 136 that the first of these, 0. Forbesi, 

 Davidson, is unquestionably congeneric with Schizotrefa elliptica, Kutorga, 

 Kutorga's genus having been established in 1848. As this species, therefore, 

 can not be used as the type of Orbiculoidea, we must assume the second species 

 as tlie typical representative of the genus, and upon this is based the distinc- 

 tion throughout the foregoing pages in the use of this term Orbiculoidea by 

 D'Orbigny and by Davidson. At the place cited in the " Prodrome " the date 

 " 1847 " stands after the name of the genus. The explanation of its use 

 appears upon page lix of the Introduction, and the date of publication of the 

 work renders its adoption untenable. 



