Note on Studcria mirabilis. By Prof. J. A. Thomson. 677 



the summit there is a terminal polyp which is larger than the others. 

 In many eases a branch has a length of 15 mm. and a maximum 

 diameter of 3 mm., but in regard to these and other measurements 

 of soft parts it must be remembered that the whole colony has 

 been much contracted by preservation in strong spirit (plate XVI. 



fig. 2.). 



The polyps have almost globular calyces or verruca?, with 

 a diameter of about 1 mm. The tentacles are in most cases com- 

 pletely retracted, and the summit of the calyx shows a sharply 

 defined circular aperture. The polyps with their calyces and pre- 

 cise circular aperture recall those of some of the Pennatulids, such 

 as Virgularids. On the wall of the calyx there are eight triangular 

 points, each consisting of two to three pairs of spicules arranged 

 en chevron, surmounting a collaret of several horizontal rows. In 

 most cases, however, the projecting spindles of the cortical ccenen- 

 elivmn hide the base of the calyx and may even intrude upon 

 it. The anthocodia is very minute and is completely retractile 

 within the globular calyx. The tentacles are short and thick, 

 apparently without spicules, and with about half a dozen pairs of 

 pinnules. 



Spicules. — Apart from a few irregular minute forms found on 

 the canal walls (and possibly extraneous) all the spicules are 

 spindles. Many are huge, most are densely warted. The warts 

 are often in close- set transverse rows, so that the spindle has a 

 striated appearance. Many of the spindles are curved in a sinuous 

 fashion ; not a few are irregularly forked (plate XVI. fig. 3). 



The following measurements were taken of the spicules, length 

 and breadth in millimetres : — 



Position of Stvderia. — If this type is to be referred to any of 

 the recognised families of the Alcyonacea it must be to the Alcyo- 

 niidse. In the retractility of the whole polyparium, as well as 

 in the mode of branching, the disposition of the polyps and 

 their armature, it is removed from the Nephthyids and Siphono- 

 gorgids. 



In certain respects, e.g. the distinct calyces into which the 

 delicate upper parts of the polyps are retracted and the large 

 longitudinal canals continued in part to the base of the colony,. 



