258 
NAUIILOIDEA. 
Sp. Char. “ Elongate oval, slightly compressed ; septa oblique, 
very approximate, rather less than a line apart in a specimen nine 
lines in diameter. Diameter at last chamber nine lines ; length 
of specimen, imperfect at both ends, one inch two lines. The 
approximation of the septa distinguishes this from every other 
[species] of the genus with which I am acquainted.” (d/‘Coy.) 
Honzon. Middle Bala. 
Locality. Ardwell, Ayrshire. 
Bepresented by two specimens, one of which is that figured by 
Salter (loc. cit.). 
Poterioceras constrictum, Hall, sp. 
1832. Spirilla constricta, vou Dechen, Ilaudb. der Geognosie von II. T. 
De la Beche, p. 530. 
1843. Nelimenia incognita, Castehiau, Syst. Sil. de I’Am^rique Septen- 
trionale, p. 33, pi. x. f. 4. 
1847. Oncoceras constrictum, Hall, Pal. of New York, vol. i. p. 107, 
pi. xli. ff. 0 a-f and 7 a-d. 
1849. Oncoceras constriction, d’Orbigny, Prodr. de Pal^ont. vol. i. p. 5. 
1863. Cyrtoceras constriction, Billings, Geol. of Canada, Appendix, 
p. 951. 
1866. Oncoceras constriction, Billings, Cat. of the SU. Foss, of Anticosti, 
p. 23. 
1869. Cyrtoceras constrictum, Safford, Geol. of Tenne.ssee, p. 290. 
Sp. Char. “ Shell curving, ventricose in the middle, abruptly 
constricted near the aperture, and rapidly tapering towards the apex; 
septa very slightly convex, numerous, approximate, slightly undu- 
lating and bending upwards on the dorsal margin ; section ovate, 
with the dorsal side narrower and somewhat obtusely angular; 
siphuncle small, dorsal [= convex, or ventral (?) border of the shell] ; 
surface striated transversely.” {Hall.) 
Hemarl's. The figure given by Castelnau of his Nelimenia incog- 
nita undoubtedly represents the present species ; it is, moreover, 
recorded from the same locality whence most of the examples in the 
Museum Collection were obtained, viz. the Falls of the Montmorenci, 
near Quebec. Castelnau’s species seems, however, to have been 
overlooked by most of the American palaeontologists. It is not 
mentioned by Hall or TVhitfield, nor does 8. A. Miller give it in his 
Cat. of Amer. Pal. Foss, even as a synonym. Scudder, however, 
records it in his ‘ Index of Genera.’ Castelnau was quite unable 
to discover the affinities of his fossil, for he describes it as a 
“singular body, probably related to the class of the moUusks or 
perhaps to that of the crinoids”; and after describing the specimen 
he gave it “ provisionally ” the name above quoted. 
