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is of an elliptical form, having the sides pressed in, but becomes round as the 
arm elongates. The growth and insertion of the auxiliary side arms in the 
column, is conformable to what was observed when speaking of Actinocrinites 
triaconta dactylus. One specimen (fig. 8. and 9.) in my possession shows the 
conical insertion of the first auxiliary arm joint very distinctly. 
The pelvis (PL. 1. fig. 5. and 6.) is saucer-shaped, composed of three plates, 
having in the depressed centre where they articulate to the column, a pentapeta- 
lous opening forming the entrance to the alimentary canal. At the upper edge 
they are excavated, forming five slightly concave spaces, showing a finely 
striated rim at the exterior margin for the firmer articulation of five intercostal 
plates. 
On account of the first INTERcostan Piares, which are of an oblong 
square form, inclining outwards, an angle is formed between each two, into 
which a first costal plate is inserted, 
The five First Cosran Prares are heptagonal and pointed, supporting 
each a hexagonal second costal plate, and a scapula. 
On the first intercostal plates (PL. 1. fig. 2.) rest a series of several hex- 
agonal oblong intercostal plates, gradually decreasing in size upwards, hav- 
ing in the angles between them and the costals a few irregular intercostals, 
placed in a double series on the sides where (as in the former species) the 
structure of the animal occasions that wider interval between two of the arms 
than between the rest, for the purpose of which we are yet unable to account. 
The intercostals and irregular intercostals mix above with the mass of minute 
plates belonging to the integument over the abdominal cavity. 
The Arms and Fincrrs. From each of the scapule proceed two first arm 
joints, and from these a second, between whose inner angles a clavicular plate 
is inserted. C. Stokes, Esq. sent me a drawing of the superior portion 
of this animal found at Dudley (Pt. 4. fig. 1.) which shows that the arms sup- 
port two hands each provided with several fingers. 
A radiating contraction (PL. 1. fig. 2.). is capable of being formed by mus- 
cular action ov each of the costal and intercostal plates, similar to that noticed 
in Actinocrinites Polydactylus, A powerful contraction (fig. 3.) arising from 
