ONONDAGA-SALT GKOtTP. 
349 
719. 25. PLEUROTOMARIA PERLATA (n. sp.). 
Pl. LXXXIV. Fig. 5 a, b, e. 
Shell depressed ; volutions about seven, flattened above, outer one angular on the margin ; 
base discoid, depressed towards the large umbilicus ; surface unknown. 
This species, in the character of its volutions, resembles P. lenticularis ; but they are more 
numerous, and more depressed. Numerous imperfect specimens have been obtained, but in 
none of these is the shell preserved, and they usually consist of fragments of two or three 
volutions. This species, as well as the preceding, can be readily identified with the figures 
given. 
Fig. 5 a. View of the upper surface of an imperfect cast. 
Fig. 5 b. Profile view of the same. 
Fig. 5 c. Parts of two volutions near the base of the shell. 
Position and locality. In the limestone at Galt, Canada West. 
720. 11. BUCANIA ANGUSTATA (». sp.). 
Pl. LXXXIV. Fig. 6 a , b. 
. Volutions narrow, rounded on their sides, expanding near the aperture. 
The specimen figured is a rough cast in limestone, preserving no remains of surface markings. 
The volutions are less extended laterally than any other species of equal size known in our 
strata. 
F ig. 6 a, b. Dorsal and lateral views of the same specimen. 
Position and locality. In the limestone at Galt, Canada West. 
721. 9. CYRTOCERAS ARCTICAMERATUM (n. sp.). 
Pl. LXXXIV. Fig. 7 a-d. 
Elongated, slender, gradually tapering and gently incurved ; septa numerous, slightly con¬ 
vex ; section transversely oval ; siphuncle dorsal. 
This species possesses some characters in common with C. multicameratum of the Trenton 
limestone, but the septa are still more closely arranged, and the section in perfect specimens is 
clearly oval. 
Fig. 7 a. A fragment of a cast, preserving, in a length of two inches, thirty-five septa. 
Fig. 7 b. A longitudinal section of another specimen. The waved and irregular condition of the 
septa appears as if due to accidental causes. 
