324 BRITISH PALAOZOIC FOSSILS. [CepHaLopopa. 
flattening of the sides, and by the antero-posterior diameter of each whorl exceeding its width. I have not 
seen the surface. The whorls are apparently not quite in contact. 
Position and Locality —Limestone of Mynydd Fron Frys, five miles W. of Chirk, Denbighshire. 
Explanation of Fiqure.—PI. 1. L. fig. 26, natural size, shewing the siphon projecting slightly at the inner 
margin of the right-hand whorl. 
TROCHOLITES PLANORBIFORMIS (Conrad). 
Ref. and Syn.—Id. 1d. Conrad, Journ Acad. Nat. &c. Philadelphia, Vol. VIII. t. 17. f. 1, and Hall, Pal. 
N. Y. t. 84. f. 3 = Lituites planorbiformis Salt. in Ap. = Nautilus primevus Salt. Geol. Journ. Vol. I. p. 20. 
Sp. Ch.—Whorls four and half, half exposed, in a very deep umbilicus, margins of the umbilicus rounded, 
but angular in the section at points of junction with the preceding whorl; circumference broadly rounded ; 
septa gently convex; siphuncle large, less than half its diameter from the inner edge; section transversely 
reniform, indented by the periphery of the preceding whorl; surface marked with very delicate, transverse, 
interrupted strize (about seventeen in one line), having a broad backward wave in the middle of the periphery 
crossed by nearly obsolete spiral stria, about three times farther apart than the transverse ones ; parallel with 
the transverse strice are several broad obsolete waves, from one to nearly two lines wide, and a few stronger 
similarly curved constrictions, produced by periodic thickening of the lip. Diameter (of small specimen) ten 
lines, proportional diameter of last whorl “width “, antero-posterior diameter of mouth ;5)- / 
Position and Lecality—Rare in the Bala limestone of Cymmerig Brook, Bala. 
Genus. HORTOLUS (Mont/:) 
Gen. Char.—Shell spiral, last chamber produced, straight; whorls in one plane, disjoined throughout ; 
septa simple ; siphon central, or nearly so. 
Differs from Zitwites in the whorls being disjoined. 
HortoLus GIGANTEUS (Sow. Sp.) 
Ref. and Syn. = Lituites giganteus Sow. Sil. Syst. t. 11. f. 4. 
Sp. Ch.—V olutions about one and half, the perfect whorl about four and half inches in diameter; straight 
portion of last whorl upwards of five inches long; two inches in antero-posterior diameter, and one and half 
inches in width; section subquadrangular ; sides flattened, marked with large rounded ribs (on the last whorl 
two lines in diameter), slightly arched very obliquely outwards and backwards, separated by concave spaces 
equalling them in width; the ribs disappear in the middle of both the inner and outer margins, the latter being 
flattened or slightly concave, crossed by the septa, which are arched nearly at right angles to the axis of the 
shell; the last two or three being from three to four lines apart; siphon large, a little eccentric towards the 
outer side. 
A young specimen of this fine shell from Builth shews the nearly circular form of the whorl before the 
production of the straight portion; it is about three inches and half in diameter, the oblique ribs rather more 
than a line thick, and strongly marked on the first half of the shell which contains the chambers; on the 
anterior half, which is without septa, they are scarcely indicated ; diameter of the mouth (the edge of which 
is obliquely sigmoidal, corresponding to the direction to the ribs and lines of growth) is in this specimen one and 
half inches, being the diameter also of adult specimens in the half volution before the straight terminal portion. 
Position and Locality—Common in the Lower Ludlow rock of Leintwardine, Shropshire; and Garden 
Quarry, Aymestry, Herefordshire; black Upper Bala shale, N. of Builth, Radnorshire. 
Horrto.ius 1BEx (Sow. Sp.) 
Ref. and Syn. = Lituites Ibex Sow. Sil. Syst. t. 11. f. 6. 
Sp. Ch.—Arched, rapidly curved at the smaller end to a semicircular hook, rather less than an inch in 
