62 PALAEONTOLOGY OF NEW YORK. 



other two are to be referred to the same genus. Mr. Whitfield* has also de- 

 scribed a species, L. minima, from the Potsdam sandstone of New York. Adding 

 to these the L. Morsensis {Mnrsii) of N. H. Winchell,! we find that the genus 

 is thus far represented by six species, but of all these the interior characters 

 of the typical species only are satisfactorily known. 



Genus BARROISELLA, gen. nov. 



PLATE II, PIGS. 14-1(!. 



1S68. Liiiffitla, Meek and Wortiien. Geological Survey of Illinois, vol. iii. p. 437, pi. xiii, tig-. 1. 



enf. 1SB6. Linr/ula. Davidson. British Silurian Brachiopoda, p. 42. 



ciif. 1870. Linr/ida, Wi.nohki.t,. Proceedings American Philosophical Society, vol. xiii, p. 248. 



ruf. 1S73. Genu.s?, Ki.\<i. Annals and Magazine Natural History, Fourth Series, vol. xii, p. 13. 



cnf. li<S\. Lintjula? , D.\vid.son. Brachiopoda Budleigh-Salterton Pebble-bed, p. 361. 



/-»/. 1SS7. Lim/ula (GlnlthVm). Viw.cn. Zeitschr. der deutsch geolog. Gesellsch., vol. xxxix, p. 392. 



Diagnosis. Shell externally as in Lincula. 



The pedicle-valve bears a high cardinal area, which does not appear to be a 

 shelf, as in Linoula and Lingulella, but a thickened triangular plate, which is 

 divided l)y ti broad pedicle-groove. On the basal margin of the cardinal area, 

 at the angles made by the lateral margins of the pedicle-groove, is a pair of 

 bosses or condyles, which have undoubtedly served either as muscular fulcra, 

 or, to some extent, as points of articulation with the opposite valve. The 

 interior of the pedicle-valve shows a subquadrate depressed area lying directly 

 beneath and almost in continuation of the pedicle-groove ; this may represent 

 the umbonal muscular scar. From its ante-lateral angles diverge two sharply 

 defined, linear depressions, which extend about one-fourth the length of the 

 shell and end abruptly. From outside and behind the extremities of these 

 depressions, begins a pair of long, curved furrows, which ;ire composed of two 

 shorter curves, the posterior rounding over the extremities of the linear de- 

 pressions referred to above, the anterior tuid longer curves gradually approxi- 

 uKiting and n(>arly meeting at a point tibotit one-third the shell's length from 

 the anterior margin. These; furrows are accompanied by low ridges along their 

 inner margin. A low median ridge, with elevated edges, begins at the posterior 

 umbonal impression, and continues to the center of the valve, widening near 



* Bulletin American Museum of Natural History, vol. i, No. ■'5, p. 141, pi. xiv, figs. 1, 2. 1S84. 

 + Geology of Filhnoi-e County, Minnesota. 1876. 



