61 
not that freedom of parts observable where room وز‎ 1 
haps, owing to this that all the joints of the han 
adhere near each other (Pr. rr, fig. 4. and 5.) 
the first joint of the tentaculum intrudes on t 
eft for increase. It is, per- 
d have laterally, where they 
a compressed figure, as also that 
he second joint above it. 
The PLATED INTEGUMENT (Pr. 1.) covering the abdominal cavity, is in tlie 
specimeu alluded to, extended beyond tbe scapulz, connecting the sides of the 
arm joints and the hands'as far as the first finger joint together, hence de- 
monstrating a considerable extension of the abdominal cavity. ` The plates are 
neatly arranged, forming a sort of rose-like appearance, of which a minute 
hexagon or heptagon forms the middle. A question here suggests itself, whether 
the animal in age loses the tentacula of the arms, and those at the commence- 
ment ofthe hand? It certainly can here readily dispeuse with an apparatus of 
detention, its fingers having increased in size and length, and as the coste and 
scapule do not grow larger in proportion, it is obvious the covered cavity be- 
tween them can only be increased by extendiug the points of adhesion of the 
integument between the arms, to which it already adheres where it covers the 
grooved canal at their inner surface; 8 y dispensing with tbe tentacula, which 
are no longer required, their articulating surfaces on the arms, furnish favour- 
able points for the angular insertion and adhesion of the plates of the integu- 
ment. ‘The increase of the size of the abdominal cavity is rendered imperious, 
by the extension of the viscera necessary for the receiving and preparing of the 
greater quantity of food, required by the organic wants of an animal materially 
increased in size and full grown. Iam nearly confirmed in the correctness of 
the above opinions, by having detected ina specimen of P. Briareus the integu-. 
ments adhering to the sides of the firstarm joint, which also had no longer a. 
tentaculum, an instance of which is also represented in Mr. Parkınson’s Or-. 
ganic Remains. Vor. ıı. Pr. xvii. fig. 2, 
Fragments of an animal approaching to P. Subangularis, but of a smaller 
and neater shape, occur iu the oolite at Dundry, and in the forest: marble. It 
must remain for further favourable opportunities to ascertain what claim these 
have to a specific distinction, or whether they belong to. a. yariety of present 
‚species. | 
