DESCRIPTION OF THE FOSSILS. 
237 
G. cyclolobus. Ph. PI. XX. fig. 40, 42. Bolland. 
Discoid, sides flat, back broad, inner whorls half concealed ; septa with four round 
lateral lobes, a small double dorsal lobe, and small acute dorsal sinuses ; the first lateral 
sinus double, the others simple, all round. 
G. mixolobus. Ph. PI. XX. fig. 43 — 47- Bolland. 
Discoid, whorls elliptical, the inner ones a little concealed ; septa with four rounded 
lateral lobes ; the first lateral sinus double pointed, second, single pointed, dorsal lobes 
and sinuses pointed. 
G. serpentinus. Ph. PI. XX. fig. 48—50. Black Hall in Bolland. 
Discoid, whorls all exposed, aperture nearly circular, delicate transverse striae ; 
septa approximate with three round lateral lobes ; two round lateral sinuses, a central 
acute dorsal sinus. 
G. spirorbis. Gilb. PI. XX. fig. 51 — 55. Black Hall. 
Discoid, whorls seven or more, round or oval, half concealed, coiled like a watch 
spring, finely striated across, as if wrapped with silk ; sutural line exangulate. The 
young are globular. 
G. rotiformis. Ph. PI. XX. fig. 56, 57, 58. Bolland ; Kulkeagh. 
Discoid, whorls many, angular, half concealed like the last, bearing a truncated 
keel, and radiating furrows. Septa as in the last. 
G. vittiger. Ph. PI. XX. fig. 59, 60. Bolland. 
Lenticular ; back bearing a truncated keel, inner whorls more than half concealed. 
G. intercostalis. Ph. PI. XX. fig. 61, 62. Bolland. 
Discoid, whorls costato-tuberculated on the sides, round on the back ; with spiral 
intercostal striae. 
G. carina. Ph. PI. XX. fig. 63, 64. Bolland. 
Lenticular, back carinated, smooth. 
G. evolutus. Ph. PI. XX. fig. 65, 66, 67, 68. Flasby, &c. 
Volutions apparent, their section round in young, oblong in old whorls ; septa with 
a deep acute dorsal sinus, and obtuse angled first lateral lobe. 
Orthocebas. An extinct genus, unknown (in Great Britain at least) 
above the coal formation. 
O. cinctum. Sow. PI. XXI. fig. 1. Bolland; Castleton; Queen’s 
County. 
Elongate, section a very short ellipse, siphuncle central ; septa distant ; shell girt 
with fine undulating raised lines. 
O. giganteum. Sow. PI. XXI. fig. 3. Plasby ; Bolland ; Closeburn ; 
Kildare. 
Elongate, section circular, siphuncle a little excentric ; septa numerous, regularly 
H h 2 
