18 PALEONTOLOGY OF NEW YORK. 



wrinkled into a sort of herring-bone pattern ; L. distinda and L. epimia, Bar- 

 rande, L. granulata, Phillips, and L. tenuigranulata, McCoy, also have very 

 characteristic surface markings, consisting of granulations or tubercles with vari- 

 ous arrangements. In the L. laviellata, Hall,* from the Clinton group of central 

 New York, and the commingled Clinton and Niagara fauna at Hamilton, On- 

 tario, the surface is covered by broad, transverse, imbricating, gently undulating 

 lines, which do not correspond with the curvature of the anterior margin, but 

 end quite abruptly on the lateral margins. Near the umbo these lines are 

 crossed by the concentric growth-lines of the shell. Of precisely the same 

 character is the ornamentation in L. zebra, Barrande, from the Bohemian 

 Etage E,f and closely similar to it is that of L. spathata, Hall, of the Lower 

 Helderberg. 



The genus Lingula reached its culmination of development in the faunas of 

 the Silurian and Devonian. In the Palaeozoic of North America alone, about 

 one hundred and twenty species (making allowance for synonyms and the 

 necessary elimination of heterogeneous forms) are now recognized. Of these 

 about seventy are from the Silurian. It is not probable that as many more 

 species are known from the same formations in other countries. 



Genus LINGULOPS, Hall. 1871. 



PLATE II, FIGS. 21-29; AND PLATE IV K, FIGS. 14, 15. 



1871. Lingulops, Hall. Notes on some New or Iinpeifectly known Forms among the Brachiopoda, 



etc. (Marcli). In advance of Twenty-thinl Rept. N. Y. State Cab. Nat. Hist. 



1872. Lingulop'i, Hall. Idem. (March). Repi-inted with Explanations of Figures. 



1873. Lingulopa, Hall. Idem. Twenty-third Rept. N. Y. State Cab. Nat. Hist., p. 245. 



1874. Lingiilops, Davidson and King. Quart. Journ. GeoL Soc, vol. xxx, p. Itj4. 



1875. Lhigula, U. P. James. Cincinnati Quart. Journ. Sci., vol. ii. 



Of this remarkable and interesting genus but three representatives are 

 known. Two of these are from faunas probably equivalent, but from widely 

 distant localities ; Lingulops Wkitfieldi, the type-species, from a chocolate-brown 



* This name has been applied to twii distinct species, one from the Clinton g-i-oup (Pal. N. Y., vol. ii, 

 p. 55, pi. XX, figs. 4 a, b, c), the other fi-om the Niagara shales at Lockjiort and elsewhei'e (Geol. Rept. Fourth 

 Dist. N. Y., 1843, p. 109, fig. 2 ; Pal. N. Y., vol. ii, 1847, p. 249, pi. liii, figs. 1 and 2). The latter has 

 priority, and the former, that above mentioned, may I'eceive the designation, Liiigula fceniola. 



tSyst. Sil., vol. v, pi. 105, fig.>. 



