64 
PALAEONTOLOGY OF NEW YORK. 
placed very far back, especially in the brachial valve, where the thickened area 
against which they abut, and the semicircular lateral impressions bounding the 
area, suggest the compound central muscular thickening and the curved lateral 
scars seen in some species of Obolella. The long curved anterior furrows in 
both valves at once suggest homology with the vascular trunks or pallia! 
sinuses in Lingula. No specimens of these shells, however distinctly the in¬ 
terior markings may have been preserved, give any indication of branches from 
either side of these furrows, and it may be well to bear in mind in determining 
the relations of the genus, their similarity to the long laterals in Obolella. 
On the basis of interior characters, Lingula subspatulata is the only species 
known that can be safely referred to this genus. This form was described by 
Meek and Worthen in 1868,* * * § from the black shales (Genesee horizon) underly¬ 
ing the Goniatite limestone (Kinderhook) near Rockford, Indiana, and Union 
county, Illinois. Professor A. Winchell| has suggested the specific identity of 
a form found in the black shales at Vanceburg, Kentucky, and elsewhere on both 
sides of the Ohio river, included within the Waverly series, but this is evidently a 
higher horizon than the Indiana and Illinois occurrence, and we surmise that the 
Waverly form mentioned by Professor Winch ell will proveto be the L. Melie, Hall. 
The same author also suggests the identity of L. subspatulata, Meek and Worthen, 
with his L. membranacea, from the Burlington sandstones. The only figure we have 
of this latter form is one given by Meek:}: in 1875, in which there are indications of 
the high cardinal area and apophyses in the former species, though the quadrate 
outline of L. membranacea gives it a specific impression distinct from that of L. 
subspatulata. The Lingula palifor mis, Hall, of the Hamilton shales of New York, 
may also prove to belong to Barroisella, though the character of the cardinal 
area and the internal markings as far as now known, do not serve to distinguish 
it from Lingulella. With Barroisella may be compared the Bohemian species 
Lingula Davidsoni, Barrande,§ and L. insons, Barrande,|| from the Etage D. 
* Geological Survey of Illinois, vol. iii, p. 437, pi. xiii, fig. 1. 
t Proceedings American Philosophical Society, vol. xii, p. 248. 
t Palaeontology Ohio, vol. ii, pi. xiv, fig. 4. 
§ Syst&me Silurien, vol. v. pi. 104, fig. viii. 
| Systeme Silurien, vol. v, pi. 105, fig. x. 
