CYRTINA OF THE UPPER HELDERBERG GROUP. 
265 
observed at the time lie published his description. In specimens of three 
species ( Cyrtina rostrata, C. hamiltonensis and C. dalmani ), the spires are 
oblique to the direction of the valves, their apices terminating in the 
rostral part of the ventral valve. This feature is likewise common to 
some species of Spiriferina, as has been beautifully shown by M. E. 
Deslongchamps in his “ Etudes Critiques sur lets Brachiopodes nouveaux ou 
peu connus ,” in S. rupestris, S. pinguis and S. hartmanni. The form of the 
spirals is also more cylindrical than ordinarily observed in Spirifera, 
and in this respect also resembling those of CyrtinA. The spiral coils in 
some species of Spirifera are oblique to the axis of the shell, and this 
feature has been shown by Mr. Davidson in Spirifera bisulcata (British 
Garb. Brachiopoda, PL vi, fig. 17), and by Geinitz and Gutbier in a spe¬ 
cies of Spirjfera referred to S. cultrijugatus of Rcemer.* So far as at 
present known to me, this genus does not extend below the horizon of 
the Niagara group. 
In view of these facts, it becomes necessary to make the following 
corrections and references to previously described species. 
Cyrtina pyramidalis. 
Spirifer'pyramidalis : Hall, Palaeontology of New-York, Vol.il, pa. 266, pi. 54, f. 7. 1852. 
This species is from the shale of the Niagara group. 
Cyrtina dalmani. 
Cyrtia dalmani : Hall, Tenth Report on the State Cabinet, p. 64. 1857. 
“ « .- Idem, Palaeontology of New-York, Vol. iii, pa. 206,. pi. 24, f. 2. 
From the shaly limestone of the Lower Helderherg group. 
Cyrtina rostrata. 
Cyrtia rostrata : Hall, Tenth Report on the State Cabinet, p.64. 1857. 
“ << : Idem, Palaeontology New-York. Vol. iii, pa. 429, pi. 96, f. 1 - 6. 
From the Oriskany sandstone. 
# Die -VersteinerUngen des Zechsteingeberges und Rothliegenden, oder des Permischen Systems in 
Sachsen : yon Hanns Bruno Geinitz, Dr. Phil., und August Yon Gutbier, Konigl. Sachs.-Major. 
Heft I by Dr. H. B. Geinitz, Tab. v, fig. 9. 
[ Paleontology IV.] 
34 
