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PALAEONTOLOGY OF NEW YORK. 
NOTE TO PAGE 128. 
The genus Orbiculoidea of D’Orbigny was first defined and exemplified in 
the Prodrome de Paleontologie, 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 their merits. It is shown on page 136 that the first of these, 0. Forbesi, 
Davidson, is unquestionably congeneric with Schizotreta 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 the 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. 
