272 
THE VOYAGE OF H.M.S. CHALLENGER. 
ment. Walls thin, compactly built ; exterior more or less rough, often acerose with 
partially embedded sponge-spicules ; interior smooth. Complete specimens sometimes 
yC-th inch (10'5 mm.) in length. 
The examination of Mr. Norman’s specimens of Astrorhizci catenata, one of which is 
represented in PL XXVII. fig. 3, has led to the conclusion that they are small examples 
of the same polymorphic species that was subsequently described by myself under the 
name Aschemonella scabra. Nevertheless, the thin hard investment and the general 
contour of the chambers are sufficient to separate the type they exemplify from Astrorhiza; 
so that, whilst accepting Mr. Norman’s specific name, the generic term Aschemonella 
must still be retained for them. Mr. Norman’s description, as well as my own, was 
founded on disjointed segments, and until quite recently the features of the entire organism 
were a matter of conjecture. Further search, however, amongst material from the locality 
whence most of the specimens figured in PL XXVII. were obtained, has yielded two or 
three complete tests, drawings of which are given in Pl. XXVII. A, figs. 1-3. 
These specimens help to explain the wide diversity of form exhibited by the frag- 
ments previously collected, and in a general way to confirm the characters originally 
attributed to the species. The number of segments however in the complete test, in fig. 2, 
for instance, is far in excess of what could have been anticipated ; and it is still probable, 
judging by the contour of some of the disjointed fragments previously found, that there 
may have been considerable individual differences in this particular. Nor does there 
appear to be any uniform rule as to the mode of combination. In fig. 1 (Pl. XXVII. A.) 
the primordial segment is the largest ; in fig. 2, the earliest segment is the smallest and 
the rest increase successively in size until the test begins to branch, after which they 
diminish somewhat. The branching takes place exactly as might have been foretold : 
a number of segments are first formed in single moniliform series, then the terminal 
chamber produces two or more tubulated apertures at its distal extremity, each of which 
gives rise to a new segment. 
The drawings, Pl. XXVII. figs. 1-11, give some idea of the polymorphic character of 
the segments, but are far from exhausting the wonderful variety of odd shapes they 
assume. It may be noticed that one of them has no less than six stoloniferous tubes, 
each of which has probably communicated with a distinct chamber. In point of size the 
variation is equally striking, the individual segments ranging from Jg-th to Lth inch (0‘33 
to 5 mm.) in length. 
The walls of the test are remarkably thin, — thinner perhaps than those of any other 
type of arenaceous Rhizopods, in comparison with the bulk of the sarcode lobes they have to 
support. They are constructed of very fine sand firmly cemented, and do not appear to be 
lacking in strength. The comparative rarity of unbroken specimens is chiefly due to the 
slenderness of the stoloniferous tubes. In the fresh condition there is a considerable 
