57 



in consequence greater, more muscular, and more liable to contraction, the effect 

 produced by this is (Ft. n. 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 so much so, 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. 



* 



AUXILIARY SIDE ARMS. (PL. n. fig. 15.) Near the summit of the column 

 auxiliary side arms set off from every thicker joint; (PL. n. fig. 1 1 .) 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. (PL. n. fig. I6i) 

 They are also inserted in the intervening space between the angles of the larger 

 the elliptic mark of insertion is not transverse, (Pi., n. fig. 22.) bat placed 

 with its greatest diameter perpendicularly, thereby gaining a greater power of 

 adhesion: its circumference, by contraction, sometimes becomingslightly lozenge 

 shaped, having a transverse perforated ridge across the shortest diameter. The 

 joints of the side arms (PL. n. 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. 

 (PL. II. 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, give a 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 (PL. n. 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 PELVIS (PL. n. fig. 1. 9. and 10.) is of the sartie formation as in the for- 

 mer species. 



