57 
in consequence greater, more muscular, and more liable to contraction, the effect 
produced by this is (Pu, 11. fig. 16. 17. and 21.) that the larger joints are some- 
what flat at their exterior circumference, rounded near the articulating rim, and 
slightly convex ; whereas the smaller and thinner joints are compressed, and 
frequently somuchso, as hardly to be distinguishable, whilst the corners to which 
the striated petal-shaped markings extend are swollen and convex above and 
below. The line of articulation between every two joints becomes, from this 
disposition of convex and concave surfaces, elegantly waved. The angles of the 
column are sharper than in the former species, and the thicker joints are some- 
times externally slightly tuberculated, the results of muscular contraction. 
Avxitiary SipeArms. (PL. 11. fig. 15.) Near the summit of the column 
auxiliary side arms set off from every thicker joint; (PL. 11. fig. 11.) hence, from 
their excessive number, forming a marked and peculiar feature, whence this spe- 
cies derives its name; farther down, the side arms proceed from every second 
thicker joint, and the intervening number of joints increases to three or four of 
each kind thicker and thinner towards the lower extremity. (Pu. 1. fig. 16.) 
They are also inserted in the intervening space between the angles of the larger 
the elliptic mark of insertion is not transverse, (Pu. 11. fig. 22.) but placed 
with its greatest diameter perpendicularly, thereby gaining a greater power of 
adhesion: its circumference, by contraction, sometimes becoming slightly lozenge 
shaped, having a transverse perforated ridge across the shortest diameter. The 
Joints of the side arms (PL. 11. fig. 23. and 24.) are thin, much compressed, sub- 
elliptic, or rather lozenge-shaped, having both extremities sharply ridged, they 
gradually decrease in size, till at the end of the series they terminate in a point. 
(Px. 11. fig. 15. and 25.) As they proceed from the column they alter their 
position, their longest diameter becoming horizontal, and not perpendicular as 
at the insertion, The length of the auxiliary side arms when fully grown, and 
their frequent occurrence, givea singularly bushy appearance to the column. 
They shorten as they approximate to the summit of the column, where their 
joints become less developed. When the animal is contracted (Pt. 11. fig. 7.) 
the superior auxiliary side arms overlay the pelvis, and reach with their slender 
points to the fifth arm joint. In this case they all envelope the column in a close 
fasciculus, and thus make it appear thick and undefined. 
The Peryis (Pu, 1. fig. 1. 9. and 10.) is of the same formation as in the for= 
mer species, 
