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THE VOYAGE OF H.M.S. CHALLENGER. 
present they are commonly, though not invariably, used in conjunction with siliceous 
sand, and are laid together side by side and strongly cemented, differing entirely in this 
particular from Pilulina and its allies. 
Botellina resembles the straight Hyperammince in external contour, but the cavity of 
the tube is proportionately larger, and is irregularly divided by loosely-cemented, sandy 
dissepiments, affording support to the otherwise somewhat slender outer walls. The 
rounded end has interstitial orifices ; and this fact has been regarded as an indication that 
in the normal condition the test is sessile and erect, growing attached to stones or other 
bodies by the narrower end. 
The affinities of Aschemonella are not so easily traced, for in nothing is the type so 
remarkable as its extreme variability of contour. Except Saccammina it is the only 
genus of the Astrorhizidce which betrays any tendency to distinct segmentation, though 
even this is not an invariable character. Compared with allied forms, the sandy invest- 
ment is exceedingly thin in proportion to the bulk of the sarcode cavities, and is com- 
posed of very fine materials with an unusually hard and compact cement. 
The genus Haliphysema stands in some respects aloof from the remainder of the group. 
The test is columnar and grows attached by a spuriously segmented convex base ; the 
walls are thin and firm, and in their minute structure resemble those of Marsipella, being 
often composed to a considerable extent of sponge-spicules. 
Sub-family l. Astrorhizinse. 
Astrorhizci, Sandahl. 
Astrorhiza, Sandahl [1857], M. Sars, Carpenter, Norman, G. 0. Sars, Brady, Butschli. 
Haeckelina, Bessels [1874]. 
Astrodiscus, Schulze [1874]. 
Test free ; depressed or fusiform. Depressed forms either sub-lenticular with angular 
or irregularly radiate margin, or in branching masses. Walls thick, constructed either of 
nearly uniform fine sand very slightly cemented, or of mud, with or without a chitinous 
lining. Apertures terminal ; one at each end of the test in the fusiform species, and at 
the end of each ray or branch of the compressed forms ; often more or less blocked with 
sand. 
Little need be said of Astrorhiza apart from its species. The foregoing characters are 
sufficient for its recognition, and it is not likely to be confused with any other genus 
except the closely allied Pelosina, which, typically, consists of an undivided chamber with 
a single aperture. Astrorhiza is not known in the fossil condition. 
