344 Prof. T. R. Jones on the 



Prof. Whitfield figures and describes the (apparently) 

 smaller of the two forms above referred to, finding it abun- 

 dant in the Onondaga Salt Group (Lower-Helderberg?, Cham- 

 berlin), at Waubakee, Wisconsin. 



9. heijerditia cylindrica (Hall, 1852). 



Ci/tlierina ci/lindnca, James Hall, Palaeontology of New York, 1852, 



" vol. ii. p. 14, pi. iv. figs. 8 a, 8 b. 

 Leperditia {Isochilina) cylindrica (?), Jones, Ann. & Mag. Nat. Hist. 



1858, ser. 3, vol. i. p. 258. 

 Isochilina ci/lindrica (?), ibid. p. 2.55, and (tboI. Surv. Canada, dec. iii. 



p. 101. 

 [Not the L. (Is.) ci/lindrica, Hall, 1872, 24th Annual Report N. Y. 



State Mus. N. 11. p. 2.81, pi. viii. fig. 12 ; and Report Geo!. Surv. 



Ohio, vol. ii. part 2, 1875, p. 101, pi. iv. fig. 5. This may be a 



rrimitin.^ 



Specimens in the McGill University Museum. Labelled 

 " 1098." ^^ Leperditia cylindrica [Yla\\). Medina Sandstone, 

 Medina, N.Y." 



This is a real Leperditia^ in sandstone with Lingala 

 cuneata. 



The specimens vary in size ; some are ^% inch long and ^V 

 high, others are smaller. Some in the Geological Society's 

 collection are v\ inch long and ^V high. 



We have now some individuals of this species in the 

 " Medina Sandstone " of Medina, N. Y., associated with 

 Lingula cimeata, sufiiciently well preserved, though merely 

 casts, to show that they really belong to Lejyerditia, and not 

 to Isochilina. In the Ann. & Mag. Nat. Hist, for April 1858, 

 p. 254, I suggested that this was comparable with a small 

 Russian forrn figured in Ann. & Mag. Nat. Hist. ser. 2, 

 vol. xvii. pi. vii. figs. 11-13, which I then thought might be 

 the young L. marginata (Kcyserling), but which is now 

 regarded as the Isochilina punctata (Eichwald), see Ann. & 

 Mag. Nat. Hist. ser. 5, vol. viii. pp. 346, 347. The large 

 valve formerly referred by me to L. marginata (Keyserl.) is 

 the Isochilina grandis, Jones (Ann. & Mag. Nat. Hist. ser. 5, 

 vol. ix. p. 171). 



L. cylindrica (Hall) has been found in the " Medina Sand- 

 stone " of Oneida and Niagara Counties, N. Y. 



Genus Isochilina, Jones. 



1858. Subgenus, Jones, Ann. >fc Mag. Nat. Hist. ser. 3, vol. i. p. 248. 



1858. Subgenus, Jones. Geol. Surv. Canada, dec. iii. p. 97. 



1870. Geiuis, Jonet, Monthly Mit-rosc. Journ. Oct. 1870, pp. 187, 191. 



1872. Genus, Barrandc, Syst. Silur. lioheme, part 1, Suppl. to vol. i. 



