7 6 



reticulate pattern. The average distance between branches is about 7 mm. The calyces are 

 thickly and rather unevenly distributed on all sides of die branches. They are often contiguous, 

 but may be as much as 1.5 mm. apart. 



The individual calyces are low verrucse when the polyps are completely retracted and 

 the margins infolded; but very short cylinders whose walls are mere circular bands when,. as is 

 ordinarily the case in the type, the walls are not drawn in at the top. A typical calyx measures 

 about .3 mm. in height and 1.4 mm. in diameter. The margin is surrounded by a ring of short 

 blunt points. The walls appear quite smooth under a hand lens, but a greater magnification 

 shows them to be studded with small blunt points similar to those around the margin. The 

 polyps are completely retracted, but ordinarily the calyx margin is widely open, showing the 

 infolded tentacles below the level of the margin. The operculum is rudimentary, being represented 

 by a few very small spindles on the tentacle bases, ancl not efficiënt functionally. 



S p i c u 1 e s. The typical form is a quadripartite one in which one part is larger than the 

 others, conical or thorn-shaped and more or less tuberculate. 3 to 5-rayed unsymmetrical forms, 

 in which one point is considerably' larger than the others, are common. Symmetrical stars, 

 crosses and multiradiate forms are also seen. Spindles are rarely encountered. 



Color. The colony is very light brown. The axis is a dark golden brown with a very 

 distinct iridescence. 



On account of the small size of the spicules, this species has a surface much like that 

 of the preceding form. The shape of the calyces of the two, are, however, quite distinct. 



Placogorgia Wright and Studer (emended). 

 Placogorgla Wright and Studer. Challenger Reports, the Alcyonaria, 1889, p. 113. 



As is apt to be the case when a new genus is founded on a single specimen, the 

 original describers of the genus Placogorgia included a number of details which were not of 

 generic importance, and some of them harclly good specific characters. 



For this reason a shorter or more condensed description is preferable. 



The Siboga material contains a relatively large number of species that can properly 

 be included in this genus, and an examination of this series of forms enables us to select the 

 characters mentioned by Wright and Studer that appear to be of real generic importance, and 

 to add one other feature that appears necessary. In this way the following definition is formeel : — 



Placogorgia. Colony flabellate, seldom reticulate; calyces low cones or verrucae, their walls 

 filled with imbricating dises or Stachelplatten ; operculum composed of three spindles arranged 

 in an acute-angled triangle. 



The type, and only known species up to the present time, is Placogorgia atlantica 

 Wright and Studer. 



This genus differs from Bebryce, to which it often bears a superficial resemblance, in not 

 having the characteristic spicules of that genus, i. e. the disc with a central elevated, knob-like 

 process. There is also some resemblance of this genus to Echinogorgia in the overlapping of 



