562 BRITISH PALALOZOIC FOSSILS. | CepHALopopa. 
angulation on the lateral edge of each side; last chamber occupying nearly half of the body-whorl. Diameter 
five inches, proportional diameter of umbilicus =, antero-posterior diameter of mouth =, width of penultimate 
whorl , width of mouth at outer edge of umbilicus ,{,, width of concave periphery at mouth =. 
This species (of which only a fragment of the body-whorl has been hitherto figured) is distinguished from 
the N. discus (Sow.) by the much shorter and wider mouth, and smaller and deeper umbilicus, and the conse- 
quent much greater thickness, or less lateral compression, in proportion to the diameter. 
Position and Locality.—Rare in the carboniferous limestone of Kendal, Westmoreland. 
Explanation of Figures.—-P\. 3. H. fig. 16, side view of specimen, reduced one half linear; 16 a, section 
natural size. 
NAUTILUS TUBERCULATUS (So7.) 
Ref—Sow. Min. Con. t. 249. f. 4; Phill. Geol. York. Vol. II. t. 22. f.29; M. V. K. Geol. Russ, 
Wolk sta 2bets 12: 
Desc.—Discoid, of one and a half or two whorls commonly preserved, inner whorls very slightly concealed 
by the following ones; greatest thickness at the edge of the periphery, which is very broad and gently convex, 
and usually marked along the middle of internal casts by a faint, cord-like, mesial ridge ; edges of the periphery 
broadly flattened, slightly sloped towards the umbilicus, and divided into obtuse tubercles, which are either 
conoidal or slightly elongated in the direction of the centre of the umbilicus, beyond this area the inner 
margin of the umbilicus slopes with slight convexity very rapidly to the tuberculated edge of the preceding 
whorl; about sixteen tubercles on each side of each whorl; the septa moderately convex, the edges moderately 
coneave towards the mouth, both on the sides and periphery, forming a forward rounded angle on the line where 
the tubercles are placed; siphuncle very large, central; last chamber occupying rather more than one-third of 
the last whorl. Width of mouth eleven lines, proportional antero-posterior diameter of ditto 4. 
Our specimen only exhibits one septum, and the last chamber of this species, but it agrees perfectly with 
the chambered portions as figured by Phillips and Murchison, de Verneuil, and Von Keyserling, and tolerably 
well with the figure in the Mineral Conchology, with the exception of an apparent concavity in the periphery of 
the latter, and the want of the fine medial ridge. On writing to Mr Sowerby, however, he most kindly fur- 
nished me with exact measurements and outline of the original specimen, which agree exactly with our example, 
in the broadly-convex periphery, trace of the medial ridge, &e. In the Geology of Russia a portion of the 
external shell is mentioned, proving the surface to have been marked by fine transverse lines of growth, arched 
backwards on the periphery, to correspond with the sinus in the outer lip. According to both those authorities 
there is a septum at each tubercle, and one between each pair; and taking the entire diameter as 100, the pro- 
portional diameter of the inner edge of the umbilicus is jj, (to 333), the width of the exposed portion of the 
penultimate whorl is ; (to ;;), the antero-posterior diameter of the mouth % (to #4), and the width thereof 
is &; the proportions in brackets being those of Phillips’s figure, the others from Murchison, de Verneuil, 
and Von Keyserling. 
Position and Locality.—Rare in the carboniferous shale of Halifax. 
NavtiLus TuBEROSUS (A/°Coy). PI. 3. H. fig. 15. 
Ref.—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. XII. 
Dese.—Discoid, greatest width of the whorls at the angle bounding the periphery, which latter is very wide, 
moderately concave in the middle, and having the angle on each side undulated into large, obtuse, tubercles 
(about an inch and half from tip to tip on last whorl) ; sides sloping rapidly with slight convexity to the umbili- 
cus; mouth, subquadrate, angles rounded, inner side smaller than the other three. Diameter seven inches, 
nine lines; width of last whorl, two inches, two lines; width of periphery two inches, ten lines; at inner edge 
one inch, ten lines; diameter of umbilicus about three and half inches. 
I have not distinctly seen the surface of this very large species, but it seems to be smooth. The compara- 
tive flatness and width of the sides, more quadrate mouth, and deeply concaye periphery, easily distinguish it 
