DESCRIPTION OF THE FOSSILS. 
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Gilbeutsocuinus. New genus. Basal joints five, forming a pentagon : 
suprabasal five, hexagonal, forming a decagon with five reentering angles 
from which proceed five heptagonal first costals, and five hexagonal 
second costals, bearing a pentagonal scapula supporting joints which 
combine into round arms perforated in the centre. First intercostals 
pentagonal. The following species have been usually referred to llho- 
docrinus (Miller) — from which, as it appears to me, they differ entirely. 
1 dedicate the genus to Mr. Gilbertson, whose name will ever be 
honourably associated with the crinoidea. 
G. calcaratus. Ph. PI. IV. fig. 22. Holland. 
Base concave ; all the plates convex ; ten prominent tubercles round the base, five 
of these very large. 
G. mammillaris. Ph. PI. IV. fig. 23. Bolland. 
All the tubercles mammillary ; on the base ten larger than the rest. 
G. bursa. Ph. PI. IV. fig. 24, 25. Bolland. 
Subglobose ; base concave ; all the plates convex. 
Pentremites. 
* Pelvis conical. (Ovaria absent?) 
P. inflatus. Gilb. PI. III. fig. 1, 2, 3. Bolland. 
Balloon-shaped ; ambulacra narrow ; poriferous plates crenulated. 
P. acutus. Gilb. PI. III. fig. 4, 5. Bolland. 
Pyramidal, five angled ; ambulacral spaces wide and short. In fig. 5, the ambula- 
cral plates are partially removed, in fig. 5 * completely. 
P. pentangularis. Gilb. Bolland. 
Miller has figured it as a platycrinus and added arms ! 
* * Pelvis flat or concave ; ovaria five, one larger than the rest. 
f Suture of scapulte medial. 
P. elliptieus. Sow. PI. 111. fig 6) 7, 8. Bolland. 
Profile elliptical ; contour pentagonal. 
P. orbicularis. Gilb. PI. HI- fig- 9- Bolland. 
Globose, ambulacra narrow, approximate at the base. 
f f Suture basal. 
Derbiensis. Sow. PI. III. fig. 10. Grassington ; Derbyshire. 
Ilf Suture apicial. 
P. oblongus. Gilb. PI. III. fig- H> 12. Bolland. 
Ambulacra broad ; interambulacral areae concave, longitudinally striated. 
P. angulatus. Gilb. PI. 111. fig. 13. Bolland. 
More globular than the last ; ambulacra approximate at the base. 
