■(578 Transactions of the Society. 



Studeria resembles Nidalia, but the Xidalia colony is unl (ranched, 

 and there are many other differences apart from Studeria's retractile 

 polyparium. In certain respects, e.g. in its huge spindles and in 

 the finger-like lobes densely covered with polyps, Studeria resembles 

 a form like Sclerophytum polydactylum, but the polyps are quite 

 different in the two, and there is not in Studeria any hint of dimor- 

 phism. The non-retractile calyces, the mode of branching, tin- 

 nature of the spiculation, and other features separate Studeria 

 from Alcyonium and several nearly related genera. So we might 

 review all the genera of Aleyoniidae, but to little profit, for there 

 is only one which can be thought of as having close affinities 

 with our new type*. That one is the genus Paralcyonium, estab- 

 lished by Milne-Edwards. Milne-Edwards gave the following 

 diagnosis of Paralcyonium : " Polyparium of a coriaceous tissue 

 towards the base and there forming a cylindrical tube with spicu- 

 lose walls, into the interior of which all the upper and soft part of 

 the polyparium, including the polyps themselves, can be completely 

 retracted."* 



In his original description of Paralcyonium, when he called it 

 Alcyonide,f Milne-Edwards gave a number of interesting details. 

 He distinguished a brown firm " foot " fixed by its base, and a 

 white, delicate, branched trunk with twigs ending in small polyps. 

 The cavities of the polyps unite in forming longitudinal canals 

 which are continued to the base, those which lie to the outside 

 having their walls strengthened by numerous brown spindles. 

 Ova are developed on lamellas in the lower part of the canals of 

 the trunk and fall into the cavity, accumulating further down. 

 On the polyps there are, according to Milne-Edwards, rows of 

 " spicules cartilagineuses brunatres." 



Wright and Studer gave the following definition of Paralcy- 

 onium in the 'Challenger' lieport on Alcyonarians (1889) : — "The 

 colony presents two distinct portions : one, the basal portion, is 

 dense, with firm walls ; the other, the head, alone bears the 

 polyps, and can be in part withdrawn into the basal part. The 

 polyp-bearing portion is but feebly lobed." In his " Versuch eines 

 Systemes der Alcyonaria " f Studer had suggested affinity with 

 Nidalia. 



Our new type Studeria agrees with Paralcyonium (1) in having 

 the polyp-bearing portion retractile into the basal portion, (2) in 

 the disposition of the longitudinal canals, and (3) in having very 

 large fusiform spicules. But there the resemblance stops, and 

 there can be no question as to the distinctiveness of the two very 

 remarkable genera. 



* Histoire Naturelle des Coralliaires, 1857, p. 129. 

 f Ann. Sci. Nat., ser. 2, iv. (1835) pp. 323-33 (9 figs.). 

 % Arch. Natur., liii. (1887). 



