» \ 
138. 
In each of the horse-shoe-like depressions traversed by a perforated ridge 
at the summit of the scapula, is inserted the first Arm Joint, of similar con- 
tour to the depression, to whose superior surface adheres a CUNEIFORM JOINT, 
(considered by Mr. Manretn as analogous to the os humeri) and indicating 
that the arm here divides, and sends off fingers'in a manner analogous to what 
we observe in the Crinoidea, 
The space between the superior angles of the scapule, is occupied by 
numerous small polygonal plates, analogous to those noticed in the genus 
Actinocrinites ; these indicate that, as in these animals, an integument protected 
by numerous plates containing in its centre the mouth, extended over the abdo- 
minal cavity containing the viscera. This is the more strongly confirmed by a 
fine specimen in Mr. Man rety’s possession, and engraved for his work, PL. xvi. 
fig. 6. which also suggests the probability that the animal was capable of con- 
tracting this integument into the form of an imperfect proboscis. 
In two eae which I have had an opportunity of examining, the 
angular points of two of the costal plates where adhering to the central piece, 
are, as well as the latter, truncated and otherwise distorted, admitting an 
additional plate, the result of injury and restoration. But, even in this 
instance, nature has not interrupted the gener al principle of muscular action, 
continuing it over the interposed plate which is marked with ridges similar to 
the costals. 
The remains of this species as already observed, occur only in chalk-pits, 
and show on fracture, that they are now converted into calcareous spar, thus 
resembling the appearance of the fracture of Pentacrinites, Asteria, and 
Echini, found in similar strata, and thereby proving the analogy which the 
calcareous concretions or ossicula of these animals bore origmally to each 
other. : 
* 
I entertain the hope that the parts of this animal of which I have been my- 
self unable to speak with certainty, will be fully defined by Mr. Manrett, who, 
by his vicinity to the chalk-pits where it occurs, has every opportunity of 
obtaining information and following up bis inquiries, 
I cannot omit to remark that there exists a considerable analogy in the 
arrangement of the plates forming the cup-like portion of Marsupites and 
