( 1124 ) 
2. Species with more than 1 stratum of median chambers. As a 
form of this nature has only been described O. multipartita Martin’). 
The median chambers occur only in more than 1 stratum at the 
periphery, where the lateral chambers are reduced; d is about 7 mm. 
Only the form found in Java has been described. It is however my 
opinion that two forms of Christmas Island described by Jones and 
CHapMAN (le), ie. O. insulae natalis var. inaequali and O. ephippoides 
should likewise be classed among O. multipartita. In the former one 
distinctly sees in the representation several strata of median chambers 
at the periphery, whilst the embryonal ventricle is large, as with 
QM. multipartita. For the rest DouvirLÉ has pointed out already that 
there was no reason for the introduction of anew species: O. ephip- 
poides (l.c.). 
3. Small species. The oldest description known of these is O. Suma- 
trensis Brapy*), which is nearly globe-shaped, d 3, h 1'/,—'/, mm. 
The median plane forms at the periphery a thin keel; only small 
macrospheric forms are known *) with certainty ; of the microspheric 
forms it is only occasionally mentioned that they can reach 15 m.m. 
diameter *). Nias ?), Sarawak *), S. Borneo *) and Christmas Island °). 
K. Martin *) has described a very small form of Timor but not 
given it a name, which seems in the main to be similar to O. Suma- 
trensis Brapy, in the middle the scale becomes gradually thicker, 
and the embryonal chamber and the succeeding one are very large, 
the Timor-form is only somewhat smaller and less globular: d1—2, 
h 1—'/, mm. Timor (Gunune InHavuw), S. Borneo’) New Guinea ®). 
Another, very small form of Timor *), however, differs decidedly 
from O. Sumatrensis by its flattening. For convenience’ sake we shall 
indicate it as O. Timor 1. 
Somewhat larger is a form described by Brapy *) as O. dispansa ; 
afterwards VerBEEK and FeNNEMA *) proved this determination to be 
1) K. Martin, Die Fossilien von Java, Erstes Heft. 1891. 
2) H. Brapy, Jaarb. v. h. Mijnwezen in Ned. Indië, 7, p. 157— 169, 1878. 
3) R. Burren Newton and R. Horzanp, The Ann. and Magazine of Natural 
History (7). 3, p. 245—264, 1899. 
4) H. Douvittt, l.c. 
5) T. Rupert Jones and F. CHAPMAN, Le. 
6) K. Martin, Samml. des Geol. Reichsmuseums in Leiden, 1, p. 1—64, 1881. 
7) K. Martin, Samml. des Geol. Reichsmuseums in Leiden, 1, p. 131—193, 1883. 
8) K. Martin, Samml. des Geol. Reichsmuseums in Leiden, 1, p. 65—83, 
9) R. Verserk et R. Fennema, Description géol. de Java et Madura, p. 1176 — 1182, 
1896. 
