15 



leaving but a thin wall of the substance of the axis which thus has a flattened section which 

 may be due to the mollusk and not a natural character. 



The water-vascular canals are mostly arranged around the axis, but some of them 

 penetrate the latter. 



Spicules. Those of the axis are deep purple in color and are large strong spindles 

 with narrow very regular whorls of blunt spines and warts. There are also triradiate forms, 

 Y-shaped spicules and irregularly branched forms, all larger than is common in this genus. 

 The spicules of the ccenenchyma are colorless and of much the same shape as those in the axis, 

 spindles with numerous whorls of verrucae being by far the most common forms, although the 

 others are not lacking. 



Color. The colony is very light yellowish brown, the axis deep purple and the polyps, 

 or at least the tentacles, yellow. 



This is the first instance in which the writer has seen a mollusk apparently living a 

 symbiotic life in the interior of the axis cylinder of a gorgonian. 



3. Siiberia macrocalyx new species. (Plate III, figs. 3, 30:; Plate XI, fig. 5). 

 Stat. 122. i58'.5N., I259'.5 E. 1264 1165 meters. Stone. 



Specimen incomplete, consisting of an erect stem with short scattered branches. Length 

 13.5 cm. The stem and branches are round, the former 3 mm. in diameter. The first branch 

 arises 2.6 cm. from the basal end of the stem and is simple. There are six other short simple 

 branches irregularly disposed on all sides of the stem. Three of these, and the stem termination, 

 end in definite swellings bearing each a clump of calyces. The calyces are irregularly distributed 

 on three sides of the proximal parts of the stem and branches and on all sides of the distal 

 parts of the colony. They are about 3 mm. apart on the proximal parts of the specimen and 

 more closely approximated on the terminal twigs, where they form definite clumps or clusters 

 with the individual calyces averaging about 1.5 mm. apart. 



The individual calyces are long, tubular and project at right angles from the branches. 

 A typical one measures 1.8 mm. in height and 2 mm. in diameter. The calyx walls are filled 

 with long thorny spindles arranged en chevron, especially on the upper parts where they rise 

 into eight angular points around the margin. The polyps are retractile, but usually rest (in the 

 type) with their collarets just above the calyx margins. The collaret is very strong, consisting 

 of several closely set rows of transverse spindles arranged en chevron over the tentacle bases, 

 where they project in definite points. Beyond this the tentacles have their dorsal surfaces 

 armed with longitudinally placed spindles. 



A cross section of the stem shows a rather thin ccenenchyma filled with slender longi- 

 tudinal , spindles, a not very well defined series of water- vascular canals around the axis and 

 an axis composed of a felted mass of slender thorny spindles and penetrated by conspicuous 

 water-vascular canals. 



Spicules. These are all slender spindles differing mainly in the number of thorn-like 



