558 BRITISH PALAZOZOIC FOSSILS. [CepHaLopopa. 
between each pair, but not regularly,) moderately and evenly convex ; siphon large, central. Surface of the inner 
whorl coarsely striated spirally, the outer whorls smooth, with very faint, transverse lines of growth, having 
a broad backward wave on the periphery; form of section of whorls almost regularly elliptical, the acute 
lateral ends coinciding with the edge of the umbilicus. Diameter of average specimen two inches nine lines, 
antero-posterior diameter of mouth ;, width of ditto “, diameter of inner edge of umbilicus “, width 
of exposed portion of penultimate whorl 34. 
This exceedingly rare species is distinguished completely from the N. tuberculatus by the great thickness, 
or width of the mouth as compared with the diameter, the much more rapidly enlarging whorls, much deeper 
and narrower umbilicus, direction of the flattening of the tubercles, acutely elliptical form of the transverse 
section of the whorls, and forward instead of backward wave of the edge of the septa at the middle of the 
periphery. The external form is almost exactly that of the N. cariniferus except for the tuberculations of the 
edge of the umbilicus. 
Position and Locality.—Very rare in the carboniferous limestone of Lowick, Northumberland. 
NAUTILUS CosTATO-coronaTuUS (/*Coy). PI. 3. H. fig. 15*. 
Ref —M ‘Coy, Ann. Nat. Hist. 2nd Series, Vol. XII. 
I give this provisional name to a fragment too imperfect to allow of full description, but so strongly marked, 
and unlike all described types, that I wish to call attention to it. The fragment is seven lines long, and 
is divided into seven equal chambers with simple edges; the surface exposed is the periphery, which is broadly 
rounded, moderately and evenly convex, the sides divided into large conoidal tubercles, each tubercle on one 
side coincides with one chamber, and there are two chambers between each pair of tubercles; the width of the 
periphery in our specimen is six lines, and it is marked with ten narrow, equal, cord-like, closely tuber- 
culated ridges, separated by slightly wider flat spaces. 
It strongly resembles the JV. twberculatus, Sow., but is distinguished by the costellation of the surface. 
Position and Locality —V ery rare in the carboniferous limestone of Lowick, Northumberland. 
Explanation of Figure.—Pl. 3. H. fig. 15*, periphery of fragment, natural size. 
NautiLus (Discites) piscus (Sow.) 
Ref.—Sow. Min, Con. t. 13. 
Desc.—Discoid, much compressed laterally ; spire of about three whorls, entirely exposed in the shallow, 
very wide umbilicus ; sides flattened, scarcely conyex ; umbilicus almost vertically sloped, with a rounded edge ; 
periphery very narrow, deeply concave, bounded by two acutely angular keels; septa moderately numerous, with 
a deep backward lobe on the periphery, anda larger one on each side; last chamber occupying about half of the 
last whorl. Diameter about seven inches, proportional diameter of umbilicus %, antero-posterior diameter of 
mouth =, width of mouth at outer edge of umbilicus ,{,, width of concave periphery ;; septa of last whorl about 
four and half to three and half lines apart at middle of sides of last chamber. 
I have not been able to see any portion of the surface, nor the siphuncle of this species ; the latter, however, 
is represented at about half way between the centre and the inner edge, by Sowerby. Under the head J. 
trochlea I have given the distinctive characters of the two species. See also WV. complanatus (Sow.). 
Position and Locality—Rare in the carboniferous limestone of Kendal, Westmoreland. 
NAUTILUS GLOBATUS (Sow.) 
Ref. and Syn.—Sow. Min, Con. t. 481.=N. Wrighti Flem. Brit. Anim. p. 250.+ NV. distrialis Phill. 
Geol. York. Vol. II. t. 17. f. 21. (young). 
Desc.—V ery globose, greatest width near the edge of the umbilicus, which is tumid, and abruptly rounded ; 
periphery broadly rounded with a nearly semicircular section; whorls two and half or three, very rapidly 
