51 
of these parts of the animal; another curious fact is also proved by them, 
namely, that the animal had the power of reproducing them when broken. Uhus 
in the late Mr. Toxrn’s, specimen, a joint broken transversely near the summit, 
is seen to have pushed forth a small hook and three other joints. (Px. u. tig. 
18.and 19.) The reproduction takes place from the centre of the old joint, the 
new formed ones having in their centre the perforation, and as yet appearing 
very weak, This is a new proof that this perforation serves as a passage to the 
nourishing vessel, and not a nerve, as many authors have, [ believe, suggested. 
The Petvis. (Pu.11. fig. 9.) On the first columnar joints rests the pelvis, 
formed of five nearly cuneiform joints having articulating surfaces probably 
resembling those of the encrinite. Their five points meet near the alimentary 
canal, they have eacha central ridge above, and as the lower part of their exterior 
circumference slopes downward to the salient angles of the column, they as- 
sume externally a leaf-like appearance. 
The First Costan Jomwrs. (Pu. 11. fig. 9.) In the five concave spaces 
formed by the five joints of the pelvis, the first costals are inserted. They slope 
at the inner truncated edge, thus forming a sancer-shaped cavity leading to 
the alimentary canal: they have two (although less conspicuous) bevelled and 
slightly plicated muscular lip-like processes; the central excavation of these, 
leading to the perforated transverse subtriangular ridge in the concave space at 
their superior surface, which has a slanting direction downwards toward the 
exterior, and serves for the insertion of the second costal joint. The exterior 
circumference is lunated in the upper part, as far as the costals adhere laterally 
to each other, having on the inferior part.a process which projects for a short 
distance into the space between the angles of the column,and has a semi-conical 
figure. 
The Srconp Costar Joints. (Pu. i. fig. 9.) The figure of these joints is 
that of a horse-shoe, having in the interior an excavated truncated terinination. 
The exterior circumference is semicircular, and their lateral edges do not ad- 
here to each other, but are united by the integuments covering the abdominal 
cavity. 
TheScarutz# (Pu. 11, fig. 9.) rest on the second costal joints, are of a 
horse-shoe figure, and adhere laterally to each other only by the integument 
mentioned above. At the superior surface, a centyal ridge extends with a 
