EEPOET ON THE FOE AMINIFEEA . 
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the rest having a single simple orifice ; and that the distinctions between them depend 
primarily on the sort of material they individually select for the construction of the test, 
and the mode in which it is incorporated. 
Turning again to the Astrorhizinze, which are characterised by their thick soft walls 
consisting of mud, or of only slightly cemented sand, — the longer subcylindrical varieties 
of Pelosina lead by degrees to similar forms of the genus Astrorhiza, which, instead of 
the single orifice, have an aperture at each end of the test ; and these, through the com- 
pressed three-mouthed Astrorhiza angalosa, to the typical condition of the genus, a 
lenticular disk with radiating arms. The Dendrophrya of Strethill Wright is little more 
than a small irregular Astrorhiza, growing adherent by one of its flat surfaces ; and the 
recently discovered Syringammina resembles an Astrorhiza with branching arms, which 
radiate equally in all directions, forming a subspherical instead of a flattened test. 
Of the Pilulintn/e, beyond the types already mentioned, Pilulina and Technitella, 
only one other form of test with the characteristic, felted, spicular walls is known ; 
namely, that of the genus Bathysiphon, which consists of an elongated somewhat tapering 
tube, the open ends of which serve as the aperture. 
The tubular series with firmly cemented arenaceous tests constituting the Sub-family 
Rfta p.dammtvtn/e, of which Saccammina is but a globular modification, may be said to 
commence with Jaculella, which is represented by a tapering sandy tube, closed at the 
narrow end. Some specimens of this genus are scarcely distinguishable from the simpler 
species of Hyperammina, which also is typified by a nearly straight tube, but with the 
broad end closed and rounded. The remainder of the Hyperammina present very 
diverse forms ; they are all tubular, either straight or sinuate, simple or branched, free 
or adherent, but invariably when perfect have a rounded initial chamber. The genus 
Rhizammina resembles the branched varieties of Hyperammina, but possesses no primor- 
dial chamber ; the wall is chitino-arenaceous and flexible, and not, as a rule, solidified 
by much calcareous or other mineral deposit. Sagenella, in like manner, has a 
branching, tubular test, but is of parasitic habit, spreading over stones and shells, the 
branches often anastomosing so as to form a sort of raised network. 
The genus Rhabdammina is connected with the foregoing by some of its irregularly 
branching varieties like Rhabdammina cornuta. The typical species Rhabdammina 
abyssorum has a radiate test consisting of three, four, or five tubular arms diverging from 
one point, with or without a central chamber. Straight varieties, with swollen centre, may 
be regarded morphologically as the two-rayed modification of the typical form, and these 
lead to the linear species, which consists of an arenaceous tube of nearly even diameter and 
indefinite length, open at both ends. Marsipella likewise is tubular and has terminal 
apertures, the test being either straight or twisted, of slender fusiform contour or of uniform 
diameter. Its most striking peculiarity results from its preference for sponge-spicules in 
the construction of the investment. They are not, however, an invariable constituent : when 
(ZOOL. CHALL. EXP. PART XXII.— 1883.) Y 30 
