Achievements of Annelida (?) and Rhizopoda. 285 
3. Comminuted dust of quartz. 
The above workers, though living together and, so to 
speak, getting their material from the same quarry, are 
most particular as to the size of the stones they respectively 
build with. 
4. Various grains of different colours, many black (apparently 
manganese), giving the whole test a grey colour*. 
5. Sponge-spicules, rarely of any other form than acerates ; 
but while one (A) will select only fragments of large 
acerates, another (B) will reject every thing save the 
smallest spicules. 
6. Globigerina-shells used exclusively. 
7. Test made of sand-grains of small size, with here and there 
a Globigerina stuck in a conspicuous manner on the out- 
side, as though for ornament. 
8. Tests formed of the minutest particles of ‘‘ Globigerina- 
ooze,’ consisting of coccoliths &c. 
9. Tests in which flat fragments of the shells of bivalve Mol- 
lusca form conspicuous objects; the fragments may be so 
built together as to form (A) a produced series of cham- 
bers (after the form of Valvulina gramen, D’Orb.), or 
(B) a flattened disk, as, for example, Astrorhiza limi- 
cola, Sandahl. 
So much for the material employed; but there are also 
various ways of working up the objects into the structures. 
Here are some :— 
B. Modes of using the Building-material. 
1. A promiscuous mixture of little pebbles of various kinds, 
ot larger Globigerine and other Foraminifera. This is, 
perhaps, the least-interesting builder (see “ coarse type 
of Nodosarine Lituola,” Carpenter, Microscope, p. 531, 
fig. 271, e). 
2. The selected quartz-grains (whether 1, 2, or 3 of last list) 
may be used in various ways—either roughly cemented 
together, with their angles projecting, as in a “ rough- 
cast’? wall: of this mode of building, Botellina, Rhab- 
dammina abyssorum, Sars, Storthosphera albida, Schultze, 
and some microscopic (annelid ?) tubes are examples. Or, 
3. They may build with most wonderful exactness, each grain 
fitted carefully into the interstices of its neighbours, so 
that there is hardly any space left to be filled up by the 
* This is the species which has just been recorded by Mr. H. B. Brady 
under the name Spiroloculinu celata, Costa, in a paper “On the Occwrence 
of Chalk in the New-Britain Group,” Geol. Mag. dec. ii. vol. iv, no. 12, 
Dec. 1877, p. 7 (separate copy). 
