33 



form is produced. Their surfaces are all covered with fine granules which are much smaller 

 than verrucae. None of them are girdled and the granules are so thick that the spicules are 

 not translucent. 



Color. The whole colony is creamy white. 



A number of specimens from Station 96 were preserved in formalin and the spicules 

 were exceedingly hard to demonstrate. A few, however, were found and proved to be of the 

 same peculiar forms as described above. 



Genus Isidoides new genus. 



Axis solidly calcareous; calyces club-shaped; spicules comparatively large bar-like forms 

 with the ends swollen and the surface comparatively smooth, without evident verrucce. The 

 operculum is composed of eight segments, each consisting of a plate formed of adherent longi- 

 tudinally disposed bars. 



i. Isidoides armata new species. (Plate VIII, figs. 2, 2; Plate XI, fig. 5). 

 Stat. 267. 554'S., I3256'.7E. 984 meters. 



The specimen is fragmentary, the largest fragment being straggling in form, 1 5 cm. 

 high and with the base lacking ; although it is partly retained in another, where it is solidly 

 calcareous. The main stem, or branch, forks 5 cm. from its base, one of the resulting bran- 

 ches being broken off 3 cm. from its base and the other forming practically the entire spe- 

 cimen. This latter is denuded to its first lateral branchlet 4.4 cm. from its origin, i.i cm. 

 above this branchlet another arises on the same side which forms the main part of the spe- 

 cimen and is about 8.6 cm. long. It bears one terminal simple twig on one side and two on 

 the other. The axis is solidly calcareous, round, 1.5 mm. thick at its base. The calyces are 

 almost all lateral in position on the main branches, but may be on all sides of the distal 

 parts of the twigs. They are irregular in distribution, averaging about 2 mm. apart. 



The individual calyces vary greatly in size and shape according to age and stage of 

 contraction of the polyps. Ordinarily they are tubular when retracted and club-shaped when 

 expanded, but the distal ends are almost always enlarged, even in retraction. A typical calyx 

 with retracted polyp measures 1.8 mm. in height and 1.4 mm. in diameter near its distal end. 

 One with the polyp partly expanded is 4 mm. high and 1.5 mm. in diameter. The calyx 

 walls are packed with comparatively large, bar-like or lenticular spicules which are criss-cross 

 but show a tendency to be vertical when the polyp is expanded and horizontal, especially 

 near the margin, when the polyp is retracted. The tentacles are closely folded over the oral 

 disk and their dorsal surfaces are heavily armed with longitudinally disposed bar-like spicules 

 like those in the calyx walls. These completely cover the dorsal surface with an imbricating 

 series, the distal ends of some overlapping the basal ends of others, and are adherent to 

 each-other so that the whole pseudo-operculum is made up of eight segments, each covering 

 one tentacle with an adherent mass of overlapping bar-like spicules. 



SIROGA-EXPEDITIE XIII b*. 5 



