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PALAEONTOLOGY OF NEW YORK. 
Davidson*- in the “dorsal” valve of the free species, Crania ( Pseudocrania) 
divaricata, McCoy. In the opposite valve of Pholidops these scars do not 
appear, and the interior margin of the callosity is uninterrupted In certain 
species, particularly those of large size which have been found as internal casts, 
the whole muscular area of the ventral (?) valve appears to be occupied by the 
scars of the anterior adductors (see Plate IY i, figs. 26, 36). The fact that in 
these cases the other muscular and the parietal scars are not defined is probably 
due to imperfect preservation. 
The substance of the shells of Pholidops is calcareous and apparently im- 
punctate. On account of their extreme tenuity it has been impossible to make 
satisfactory sections, but there appears by magnification of the surface no evi¬ 
dence of punctation. Should an impunctate character be demonstrated it will 
be another important respect in which Pholidops differs from Crania. 
This group of shells was noticed as early as 1820 by Schlotheim, who, by 
the designation Patellites (P. antiquus of the Gotland Upper Silurian lime¬ 
stone) implied its relationship to Patella. Sowerby, in 1839, essentially 
coincided with this opinion in referring an English species to Patella (P. 
implicata). Thereafter, until 1859, the American species were placed under the 
genus Orbicula, a name which at that time had come to include a great variety 
of heterogeneous brachiopods, now mainly referred to Crania and Orbiculoidea. 
McCoy, however, in 1859, considered the English species congeneric with the 
Schizotreta of Kutorga, and, not recognizing the priority of the latter name, 
placed both in D’Orbigny’s genus, Orbiculoidea. Salter, in 1859, and David¬ 
son as late as 1866, referred P. implicata, Sowerby, to Crania, and though the 
latter author in 1883 corrects this reference and recognizes the term Pholidops, 
no modification was suggested of the figures given of the interior of this 
species in the British Silurian Brachiopoda (pi. viii, figs. 15, 16 a), which are 
radically incorrect in representing the valves with posterior marginal muscular 
scars. In 1859, in a revised list of the fossils described in the first two volumes 
of the Palaeontology of New York, the term Craniops was proposed for the 
* British Silurian Brachiopoda, pi. viii, figs. 11, 11a, 12 a. 
