NO. 1923. DESCRIPTIONS OF PACIFIC ALGYONARIA—NUTTINO. 83 



This form resembles Ads spinosa Thomson and Simpson/ but 

 differs in color, and has much larger spicules, according to the meas- 

 urements given by these authors. 



Genus PLACOGORGIA ^A'■^ight and Studer (emended by 



Nutting). 



Colony flabellate, sometimes reticulate; calyces low cones or ver- 

 rucse, their walls filled with imbricating disks or ''Stachelplatten;" 

 operculum composed of three spindles forming an acute-angled tri- 

 angle in each opercular flap. 



PLACOGORGIA JAPONICA, new species. 

 Plate 13, figs. 1, la; plate 21, fig. 2. 



Colony (incomplete) 8.4 cm. long. Stem 6 mm. wide at base 

 above which it forks into two very unequal main branches, the smaller 

 of which forms the main part of the specimen. This again forks 1.6 

 cm. from its origin, and but one of the resultant branches remains. 

 Above this the stem is imbranched for 2.5 cm., when it again forks. 

 The ultimate branchlets are 3 mm. in diameter. The calyces are dis- 

 tributed on all sides, more thickly on the distal parts, forming clusters 

 on the ends of the twigs, and sometimes being as much as 2.5 mm. 

 apart on the proximal parts of the colony. 



The individual calyces are low, dome-like verrucse, a typical one 

 measuring 2.1 mm. in diameter at the base. The calyx walls are 

 fdled with spindles or long flattened plates of various forms and 

 variously arranged. Sometimes these plates encircle the base and 

 at others they are all vertical in position, looking like strong spindles. 

 In other cases the plates are haphazard in position, the distal ones 

 with a tendency to be vertical. These vertical spicules are often 

 triangular plates with comparatively straight edges, their acute 

 angles forming a series of irregular points around the margin. 



The polyp is retractile, but often rests with the collaret just above 

 the calyx margin. This (the collaret) is strong, composed of two or 

 three rows of encircling spindles. The operculum is composed of 

 three spindles forming an acute-angled triangle on each flap. The 

 points of the triangles thus formed reach almost to the center of the 

 mass of infolded tentacles. 



Spicules: These are mostly heavy plates with various contours, but 

 never forked nor conspicuously branched. They are usually oblong, 

 sometimes squarish, triangular, or roughl}^ oval in outline, seldom 

 exceeding 2 mm. in length, and have their corners rounded. There 

 are a few small spindles. 



1 Alcyonaria of the Indian Ocean, vol. 2, 1909, p. 77. 



