106 Jones— Orbitoides of Malta and West Indies. 
cular geological horizon, as far as my observations serve me; 
and the same may be said of some, at least, of the small Num- 
muline associated with Orbitoides in Sinde. Much requires to 
be learned as to the exact mode of occurrence and distribution 
of these little fossils. Orbitoides have long been, and still 
sometimes are, mistaken for Nummuline, Orbitolites, and Orbi- 
toline —all very different one from another; and even when 
they are recognized, it is often difficult to get at their specific 
characters. The species of Orbitoides can be discriminated 
more easily than those of Nummulina in some cases; for the 
vertical cross-section is important in the former, and of com- 
paratively little value in the latter; and in rock-specimens it 
is often difficult to get at the pattern followed by the alar flaps 
of Nummulina, the character whereby its different species and 
varieties can be best distinguished. 
The Nummuline in the Antiguan flint clearly belong to the 
simple ‘radiate’ group, composed both of young individuals 
and small varieties of the large Eocene Nummulites, and also 
of the existing representatives of the Nummuline genus. In 
fact we have, in this case, a small and feeble form, such as WN. 
Ramondi, Defr. (Carter, Ann. N. Hist., Ser. 3rd, 1861, vol. 
vill. p. 374, pl. 15, fig. 5); and its analogue (NV. radiata, 
D’Orbigny) is not wanting in the Vienna “Basin, in strata 
contemporaneous with but poorer than those of Baden above- 
mentioned ; it is present also in the Jamaican flint and lime- 
stone, as well as in Sinde. 
The full development of Nummuline certainly took place in 
and characterized the early Tertiary (Nummulitic or Eocene) 
period, but they neither began nor ended at that time; in 
fact, they still exist in great numbers, but are degenerate: and 
scattered individuals, neither well-developed nor of a specialized 
form, may occur in many different deposits, but be of little or 
no use in ‘ homotaxis,’ or the comparison of fossiliferous strata 
possibly equivalent as to time and geographical area. 
At all events, we see some definite points of: agreement 
between certain deposits in the Hast and the West, as to their 
faunal characters, by means of gregarious, well-developed, and 
conspicuous Foraminifera ; and. thereby a strong relationship 
is recognized for the fauna of the Viennese and Maltese areas, 
in the Eastern part of the Mid-tertiary Ocean, and that of the 
probably contemporaneous Coral-islands, in the West, which 
have their geological history elucidated by Dr. Duncan’s fore- 
going communication. 
