EEPOET ON THE ALCYONARIA, 



229 



Genus Sderoncjyhthya, n. gen. 



The stem is upright, branched; the surface, branches, and twigs bear scattered polyps, 

 which collect together in dense groups on the terminal twigs, and completely cover 

 them. The canal-system consists in the main stem of numerous narrow canals, divided 

 by thick partition walls filled with spicules. The spicules are large, spiny spindles, which 

 form a thick coat of mail around the polyps, and are continued and arranged, en chevron, 

 into the bases of the tentacles, which latter form a kind of operculum over the oral 

 region. Beneath the bases of the tentacles the spicules form a distinct collaret. 



In the shape and armature of the polyps this genus comes near to Nephthya, but the 

 condition of the stem and branches brings it closer to Siphonogorgia, Kolliker. One 

 distinguishes a more compact outer covering, and a central mass penetrated by canals, which 

 is thickly filled with spicules. The canals are irregularly polygonal in section, and are 

 absent from the centre of the stem, so that here the connective tissue filled with spicules 

 forms a kind of irregular axis. The stem and branches acquire thereby a tough, com- 

 pact consistence ; neither in spirit nor in the dry condition do their walls collapse, whence 

 they may be distinguished at the first glance from those of the true Spongodinaj. 



Sderonephthya pustulosa, u. sp. (PI. XXXVIa. figs. 2a, 2c). 



The upright colony arises from a slightly expanded base, first in the form of a main 

 stem. This after a short course gives off, mainly on two sides, rather large branches 

 rising upwards at acute angles, while on both the other sides only small branches come ofi" 

 irregularly. Both the main stem and the branches divide at the end into two or three 

 short, diverging, secondary branches. In addition to these the branches also give ofl' 

 at right angles along their course small secondary branches. Quite short terminal 

 twigs, thickly covered with polyps, arise at various intervals from the secondary 

 branches, forming, together with their polyps, roundish heads. Polyps, partly isolated 

 and partly in groups of three and more, also arise here and there at wide intervals 

 directly from the main stem and branches, in such a manner that the greater part of the 

 branches and of the stem appears naked. The polyps have a wurt or club-like shape and 

 project at right angles from their sup^^ort. 



Height of the colon}', 

 Diameter of the main stem at its base, 

 Diameter of the main stem in the centre. 

 Length of one of the larger branches, 

 Length of a polyp-bearing twig. 

 Diameter of the same, 

 Length of a polyp, . 

 Diameter of the same. 



