ONONDAGA-SALT GROUP. 
345 
GASTEROPODA. 
708. 19. MURCHTSONIA BIVITTATA (». sp.). 
Pi.. LXXXIII. Fig. 1 a, b. 
Spire elongated; volutions numerous (more than twelve), rounded, a little flattened in the 
cast, very gradually increasing from the apex ; aperture unknown ; surface unknown ; columella 
marked by a double spiral fold or carina. 
I refer this species to the Genus Murchisonia, without having been able to verify the cha¬ 
racters of the surface. The specimens examined are all casts, with the single exception of fig. 
1 b, which shows the interior of the shell and the broken edges of a longitudinal section. The 
succeeding species is marked by a carina below the centre of the volution, as shown in a mould 
of the shell, indicating its relations with Murchisonia. The present species, of similar form and 
general characters, I have therefore referred to that genus. The very gradual increase in the 
size of the volutions is one of the striking characters of the species, though exceeded in the 
following one. 
Fig. 1 a. A cast of six volutions from the central part of the shell. There were originally about five 
or six above the highest one shown in the figure. 
Fig. 1 b. A longitudinal section of several volutions, showing the columella, marked by a double 
spiral fold, and .the edges of the broken shell. 
Position and locality. In the limestone at Galt, Canada West. 
709. 20. MURCHISONIA LONGISPIRA ( n. sp.). 
Pl. LXXXIII. Fig. 2 a, &. 
Spire extremely elongated and very slender; volutions numerous, rounded on the surface 
and carinated below the centre ; surface unknown. 
The mould of one specimen of this species shows impressions of a carina below the centre 
of the volution, but the impressions of striae are not preserved. In the fragment fig. 2 6, nine¬ 
teen volutions are visible; and in a mould of the same species, I have counted twenty-five, and 
the base still imperfect. The columella is proportionally larger than in the preceding species, 
and shows no fold or carina. The slender spire and more numerous volutions are sufficient to 
distinguish this one from all the other species of the rock, and indeed from any species known 
in our strata. 
Fig. 2 a. A mould of the middle part of the spire, preserving a portion of the shell and columella 
near the base. 
Fig. 2 b. A fragment showing in the upper part the cast of the interior; the lower part of the 
specimen preserves the shell, which is divided longitudinally. 
Position and locality. In the limestone at Galt, Canada West. 
