ADDENDA. 
489 
PHOLIDOPS. 
Among the fossils described in the second volume of the Palaeontology of 
New-York, there is a Discina-\ike or patelloid shell, which I there termed 
Orbicula squamiformis *. 
The shells heretofore referred to the Genus Orbicula are properly 
Discina ; and all the shells of this genus, which we know, have the dark 
color and phosphatic composition of the recent species. The shell referred 
to above, and other similar forms, are light-colored and calcareous in com¬ 
position, and a farther discovery of similar forms proves them to have no 
relation with Discina. It is not easy to determine whether these small 
shells are bivalve brachiopods, or univalve like Capulus; since the only 
specimen seen, with two valves conjoined, admits of some doubt as to the 
parts being in their natural relation to each other. From the resemblance 
of the interior of one of these shells, and the flattened triangular space 
beneath the apex, I had supposed them to have some relation with Crania; 
but in order to avoid any confusion, I have not adopted a name suggestive 
of any such relation, which may after all be merely apparent; and I would 
suggest the name Pholidops, from the squamiform appearance of several of 
the species. 
Genus Pholidops (n. g ). 
Shells small patelliform : apex subcentral, excentric or terminal. Surface 
marked by concentric lamellae of growth, which are more expanded 
on the posterior side. Interior a shallow oval cavity, with bilobed 
muscular impressions ; the margin flattened or slightly deflected, and 
entire. 
* Palaeontology of New-York, Vol. ii, p. 250. 
[ Palaeontology III.] 
62 
