149 
PLATE 
II. Pentacrinus Caput Medusa, p. 51. 
All the figures, with the exception of 18. to 22, are considerably larger than natural. 
I. Pentacrinites Briareus, p. 56. 
II. Pentacrinites Briareus, p. 57.4 
i. Pentacrinites subangularis, p. 59. 
Pentacrinites subangularis, ' 
HI. Pentacrinites ici ped 
— Pentacrinites tuberculatus,* p. 64. 
— Genus. Poteriocrinites, p. 67. 
— . Poteriocrinites crassus, p. 68. 
—  Poteriocrinites tenuis, p. 71. 
— Genus. Platycrinites, p. 73. 
Platycrinites levis, p. 74. 
II. Platycrinites levis, p. 75. 
Fig. 33. to 51. Jarger than natural size. 
| 
—  Platycrinites rugosus, p. 79. 
[ Platycrinites tuberculatus, ] 
| Platycrinites granulatus, | 
Platycrinites striatus, } p. 81. 
| Platycrinites pentangularis, } 
— Genus. Cyathocrinites, p. 85. 
—  Cyathocrinites planus, p. 86. 
— Cyathocrinites tuberculatus, p. 88. 
—  Cyathocrinites rugosus, p. 90. 
— Cyathocrinites quinquangularis, p. 92. 
—- Genus. <Actinocrinites, p. 94. 
I. Actinoerinites triaconta dactylus, p. 96, 
If. Actinocrinites triaconta dactylus, p. 98. 
Ill. Actinocrinites triaconta dactylus, p. 99. . 
6: 
* T regret, when describing Pentacrinites tuberculatus, not to have stated particularly that 
its columnar joints when not fully formed, are like those of other Pentacrinites, considerably 
thinner than at a subsequent stage of growth, and alternately larger and smaller. I should also 
have further observed, that the exterior surface of the joints which, in the older specimens, as 
represented in the plate, is studded with irregular tubercles, has in these young and thinner ones 
only a single row of such tubercles ranging regularly round the middle. The cause of this appears 
to be that as these tubercles arise from the contraction of the investing muscular membrane, they 
are therefore more regular and distinct in the earlier and non-cartilaginous state of the joint. 
x 
