204 THE VOYAGE OF H.M.S. CHALLENGER. 



Spongodes dendrojyhyta, n. sp. (PI. XXXVIc. figs. 2a, 2b). 



Resembling Spongodes Jlorida and Spongodes cprymbosa, but more luxuriantly and 

 loosely branched, with the polyps surmounted by large, spiny spinules. 



The upright stem consists of a short, spindle-shaped, barren trunk, which is attached 

 at the base by means of stolon-like processes to Mussel shells, fragments of stone, grains 

 of sand, &c., and a thick stem-portion from which numerous loosely ramified branches are 

 given ofi" on all sides, bearing at their ends umbels of polyps. Owing to the loose 

 ramification and the distances which separate the different umbels of each twig, the stem 

 and branches, together with their ofi'sets, are visible everywhere in the polyp-bearing 

 portions of the colony. The branches are of difi"erent lengths, so that the umbels project 

 for various distances, and the entire colony calls to mind a luxuriantly branched tree. 



The whole colony is 100 mm. high and 85 mm. in greatest diameter. The length of 

 the barren trunk is 20 mm., and its diameter 18 mm. Length of one of the larger 

 branches 36 mm. Diameter at the base 12 mm. 



The stem diminishes somewhat in size below, with a rather flabby outer covering, which 

 when dry becomes wrinkled. At a height of 20 mm. the first branches come ofi" around 

 the circumference ; they are not, however, all at the same level, but some are higher 

 than others. The branches are broad and flattened from above downwards ; ramification 

 takes place for the most part in a plane perpendicular to the long axis of the stem. 

 Coming off" straight from the latter their twigs sink downwards somewhat, and thus 

 protect, roof-like, the upper portion of the trunk. Further up the stem, which increases 

 somewhat in diameter, arise irregularly and from all sides several larger branches, which 

 quickly ramify. At first they come off at right angles, but their twigs are placed more 

 vertically and directed towards the summit ; in shape they are more cylindrical than the 

 first set. 



The end of the stem bifurcates into two short divergent branches. The ramification of 

 the branches is analogous with that of the stem. The lateial branches arise at diffierent 

 heights ; from these twigs come off, whose secondary twigs finally bear the groups of 

 polyps. Since the twigs grow to about equal heights their secondary twigs form, with 

 the polyp heads, umbels. Owing to the strong divergence of the secondary branches 

 the umbels of one and the same secondary branch again form, amongst themselves, larger 

 umbel-like groups. Each terminal twig bears a bundle of five to seven polyps, whose 

 heads are surmounted by large spicules projecting like needles above the umbels. 



The entire colony is somewhat flabby, only the terminal twigs and the umbels are 

 more rigid. 



In the barren trunk the mesoderm of the lower portion is filled with red sjaicules of a 

 peculiar shape, disposed at regular distances from one another. They are mostly crosses, 

 whose arms are placed vertically or obliquely to one another, like an X, and which may 



