4. Plexaura platystoma new species. (Plate II, figs. 2, 2 a; Plate IV, fig. 4). 



Stat. 43. Anchorage off Pulu Sarassa, Postilion Islands. Up to 36 meters. 



Colony of irregular and straggling habit, 16 cm. in height. The main stem gives off 

 four branches of very unequal size, one of which arises about 5 cm. from the base. This 

 becomes the main part of the colony, bearing several short stubby branches very unequally 

 distributed, and one large descending branch producing a number of slender undivided branchlets 

 in an indistinctly pinnate manner. The diameter of the main stem and largest branch is 1.8 mm. 

 The calyces are entirely included and rather sparsely distributed on all sides of the stem and 

 branches. The polyps in retraction draw the calyx margins together so that the apertures are 

 almost obliterated. In the dried fragment of a branch, however, the apertures are really much 

 larger than in either of the preceding species. 



The individual calyces, although hardly evident externally, are really considerably broader 

 than in the other species described. The apertures are oval, the long diameter being parallel 

 with the axis. The longer diameter of the calyx is about 1.5 mm. The polyps have eight 

 longitudinal bands of slender spindles, and the tentacles have a number of delicate spindles on 

 their dorsal surface. These latter are arranged in two longitudinal series on each tentacle, so 

 as to approach the en chevron arrangement on the proximal portions. The layers of the ccenen- 

 chyma are not well defined. 



A cross section of a branch shows a moderately thick ccenenchyma. well-defined but not 

 numerous watervascular canals, and a horny axis with a white, noncalcareous core. 



S p i c u 1 e s. These are rather slender, usually curved spindles of the same general type 

 as in Plexaura attenuata, but larger than any others thus far described in this report, some 

 of them attaining a length of i mm. The annular arrangement of the tubercles is not so well- 

 marked as in P. attenuata. 



Color. Very pale gray, almost white, in alcohol. The axis is golden brown proximally 

 and very pale distally. 



5. Plexaura pinnata new species. (Plate I, figs. 3, 30; Plate IV, fig. 5). 



(The locality can not be given, as the label is missing). 



Colony flabellate in form, 16 cm. in height and with a spread of 9 cm. The main stem 

 has been broken just above the origin of the first main branch, which thus constitutes practically 

 the entire specimen. This branch bears numerous branchlets in a pinnate manner, but they are 

 neither opposite nor regularly alternate. The calyces are regularly distributed on all sides of 

 the stem and branches, and are about i mm. apart. 



The individual calyces are included, there being no external swelling except a slight 

 tumidity about the margin, as in other species of this genus. The aperture is quite small, usually 

 round, the tentacles being sunken below the eight-lobed fringe around the inner side of the margin. 

 The polyp is much compressed, when retracted, a longitudinal section being an oval whose width 

 is greater than the length. There are a few delicate spindles in the polyp body and tentacles. 



