498 TRANSACTIONS OF SECTION D. 
18. On the Distribution of Saccammina spherica (M. Sars) and Psam- 
mosphera fusca (Schulze) in the North Sea; particularly with 
reference to the Suggested Identity of the Two Species. By 
Epwarp Hrron-Auien, F.L.8., F.G.8., F.R.M.S., and Arruur 
Earuann, F.R.M.S. 
These foraminifera, belonging to the family Astrorhizide, and originally 
described as from the North Sea, but occurring also in all the great oceans, have 
been the subject.of considerable controversy. Dr. Ludwig Rhimbler asserts that 
Psammosphera is only an immature stage of Saccammina. Several zoologists 
have accepted his view, apparently without any verification of the evidence ten- 
dered, except in the case of Dr. Liicke, who supports Rhiimbler’s theory in 
general, although differing in certain minor conclusions. 
Their observations may be divided into two groups—(1) The nucleolar struc- 
ture of the protoplasm, and (2) the nature of the composite shell wall and its 
cement. We do not propose to deal with the first group of observations, beyond 
recording our opinion that, in the present state of knowledge of protoplasm in 
the Astrorhizide, no generic distinctions can be based on such evidence alone. 
Our observations will be confined to an analysis of their evidence as based on the 
structure of the composite test. 
Rhimbler’s description of the life history of Saccammina may be divided into 
seven stages, which again fall into three groups, each of which, in our opinion, 
represents a distinct and specific organism. 
The stages are as follows :— 
Stace I,—A small portion of protoplasm is extruded (from the parent Saccum- 
mina assumed), and settles on the parent shell, or on an adjacent sand-grain. 
It secretes a sessile monothalamous test of extremely fine sand-grains, and of a 
white colour. 
Stacy II.—Numerous sponge spicules are built into the test, which becomes 
hispid. 
Srace I1I,—The spicules are discarded and replaced by larger sand-grains. 
These three stages form the first group, the ‘ Primitiv-gehaiis’ of Rhiimbler. 
Sracu 1V.—The sessile organism becomes detached. The sand-grains are re- 
placed by larger grains irregularly cemented together. The exterior is very 
rough, and there is no aperture. Z'his stage forms the second group, the ‘ Psam- 
mosphera’ stage of Rhiimbler. 
Stace V.—The rearrangement of the larger sand-grains with their flat surfaces 
on the exterior of the test causes it to assume a more regular outline. A chink 
or fissure appears between several grains, which eventually develops into the 
general aperture. 
Stacy VI.—The fissures between the sand-grains are filled up with a mortar of 
cement and small grains, The test assumes a regular pyriform outline owing to 
the development of the aperture. 
Srace VII.—The internal fissures are similarly filled. The test becomes nearly 
globular, with a large general aperture situated on a nipple-like protuberance. 
These three stages form the third group, the ‘ Saceammina’ stages of Rhiimbler. 
Now, if Rhiimbler’s theory is to hold ground it is evident that these three 
stages should be constantly associated in dredgings. Such is not the case. As 
a result of the examination of about 150 dredgings, made over an enormous area 
in the North Sea and the adjacent waters, we have no hesitation in affirming that 
the life-history of Saccammina, as recorded by Rhimbler, is a composite sketch, 
involving three separate and generally recognised specific organisms :— 
Stages I. to III. represent the life-history of Crithionina mamilla (A. Goés), 
a sessile rhizopod which, although often associated with Saccammina spheerica, 
has a wide distribution apart from that species. 
Stage IV. is Psammosphera fusca (Schulze), an extremely variable species, 
which occurs both free and sessile, but is in all its stages normally recognisable 
by the absence of a general aperture. In our dredgings it often occurs with 
Saccammina sphcerica, but more frequently without. It is capable of existence 
under conditions of depth and surroundings in which Saccammina NEVER exists. 
Where co-existent with Saccammina it frequently attains a size equal to or 
