DESCRIPTION OF THE FOSSILS. 
233 
N. costalis. Ph. PI. XXII. fig. 30. Queen’s County ; Kildare. 
Spheroidal, umbilicus deep, rounded, whorls covered by transverse flutings, the 
interstices rising to sharp ridges on the back, and uniting obscurely into undulations on 
the edge of the umbilicus. Constrictions at intervals parallel to the ridges. Mouth 
lunate. On the shell are elevated striae parallel to the ridges. It grows very large. 
N. sulcatus. Sow. PI. XXII. fig. 31, 32. Castleton ; Kulkeagh, &c. 
in Fermanagh ; Bowes ; Northumberland ; Coalbrookdale ; Cumberland. 
Discoid ; whorls exposed, ventricose near the inner margin, with two small spiral 
furrows, concave on the side; two keels toward the back which is concave. Stria; 
line, sigmoidal. Septa concave outwardly ; siphuncle nearer the outer edge. 
N. tetragonus. Ph. PI, XXII. fig. 33, 34; PI. XVII. fig. 24. Kul- 
keagh; Bolland; Northumberland. 
Flat, discoidal, whorls tetragonal, back slightly concave, with a small spiral ridge 
within the angles ; strirn bent, sharp, rising into plaits on the edges : septa concave 
outwardly ; (oblique undulations on the sides of the cast.) \ ar. (3. inner edge rounded. 
N. subsulcatus. Ph. PI. XVII. fig. IS, 25, Kildare ; High-Green- 
wood ; Bolland ; Coalbrookdale. 
Discoidal, smooth, with many sharp sigmoidal and some spiral stripe ; whorls 
quadrangular, the back concave along the middle, bevelled to the side ; the sides concave 
toward the outer edge, and convex toward the abrupt marginal slope, siphuncle near the 
outer edge, aperture oblong, (analogous to N. sulcatus.) 
N. oxystomus. Ph. PI. XXII. fig. 35, 36. Florence Court; Ennis- 
killen ; Isle of Man. 
Very depressed, lenticular, smooth, back acute; inner volutions half exposed; septa 
concave outwards. The septa are shewn in the figure as far as they could be traced, 
Goniatites, Von Buch. An extinct genus unknown in superior strata. 
G. striatus. (Amin, striatus, Sow.) PI. XIX. fig. 1—3. Bolland; 
Flasby ; Derbyshire, & c. 
Shell very convex, umbilicate, spirally striated, (with internal strengthening trans- 
verse ridges, leaving bent constrictions on the mould) ; latero-dorsal lobes of the 
septa angular. The constrictions on the mould are extremely variable in number. 
Where very few the septa are closer. Figure 3, may be taken as a type of the ex- 
ternal edge of the septa of the genus ; the arrow points toward the aperture, and passes 
along the middle of the back. The nomenclature used in the following pages will be 
understood from the subjoined notation, referring to fig. 3. 
D dorsal region, \ included between lines; the internal edge of the sep- 
L. lateral region, f turn is not regarded. M. is generally disregarded 
M. marginal or umbilical I in description and is omitted in all the other figures. 
region, / 
