64 PALAEONTOLOGY OF NEW YORK. 



placed veiT far back, especially in the brachial valve, where the thickened area 

 against whicli 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 pallial 

 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 tlie l)asis of interior characters, Lingula subspatulata is the only species 

 known tliat 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. WiNCHELLf 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 Winciiell will prove to 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 paliformis, 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, j). 248. 

 J PaliEontology Ohio, vol. ii, pi. xiv, fig. 4. 

 § Systome Silurien, vol. v. pi. 104, i\g. viii. 

 I Systfeme Silurien, vol. v, pi. lO.o, fig-, x. 



