440" Fossils of the Chazy Limestone » 



Orthis acuminata, (N. s.) 



Fig. 19. 



Description. — Of this species a single specimen only (a ventral 

 valve,) has been found y but in good preservation. The hinge-line 

 is much longer than the width of the shell, being produced so as 

 to form extended ears, like those of many of the spirifers ; the 

 sides converge from the ears to the front angles ; the front margin 

 is nearly straight and parallel with the hinge-line, excluding the 

 ears ; the form is depressed conical, with a scarcely perceptible 

 mesial sinus ; the beak gently depressed, but not incurved; area 

 large, and slightly curved ; foramen very broad, open triangular, 

 reaching to the beak. Surface covered with fine angular stria?, 

 about six in one line at the margin ; they appear to bifurcate near 

 the beak. Length of hinge-line six lines ; length of ventral valve 

 fron beak to front, two and a half lines. 



This remarkable form differs from all the Orthides of the Silu- 

 rian rocks of Canada except O. Lynx, some varieties of which have 

 long acuminate ears. I am not satisfied that it is a true Orthis-. 



Locality and Formation. — Caughnawaga ; Chazy. 



Collector.-. — E. Billings. 



Orthis disparalis^ (Conrad.) 



Orthis Disparalis. (Conrad) 1843, Proc. Acad. Nat. Sci. Philadel- 

 phia. Vol. 1, p. 333. 



(Hall) 1847, Palceont. N. Y, Vol. 1, p. 119, plate 



32, Figs. 4r. a. b. c. 

 Orthis Costalis ? (Hall) 1847, Palceont. N. Y, Vol. I, plate 4, (bia> 



Figs. 4. a. b. 



Fig. 20. 

 Fig. 20. — Orthis disparalis. 



Description. — Semi-oval, the ventral valve depressed conical,, 

 and the dorsal valve nearly flat. Surface with about twenty-eight 



