52 Dr. Wallich on Polycystina tn certain Nodular Flints. 
T. hecabe; they may, however, be hybrids between the two 
species. 
8. Tertas hecabe. 
- Papilio hecabe, Linneus, Mus. Lud. Ulr. p. 249 (1764). 
N. Formosa. 
9, Ganoris glictria. 
Papilio gliciria, Cramer, Pap. Exot. ii. pl. 171. E, F (1779). 
9. N. Formosa. 
10. Ornithoptera rhadamanthus. 
Ornithoptera rhadamanthus, Boisduval, Sp. Gén. Lép. i. p. 180. n. 8 
(1836). 
2. 8S. Formosa, 
Owing to press of work it has been necessary to defer 
giving an account of the moths in this collection. 
VIIL—wNote on the Detection of Polycystina within the 
hermetically closed Cavities of certain Nodular Flints. 
By Surgeon-Major Wauiicn, M.D. 
In continuation of my previous papers on the “ Origin and 
Mode of Formation ot the Cretaceous Flints’”*, I beg to an- 
nounce the discovery by me, last summer, of a number of 
well-marked Polycystina amongst the loose fossilized contents 
of nodular flints obtained from the Surrey gravel-pits. In 
common with other observers I have often noticed minute 
objects in flint sections, which are, in all probability, the re- 
mains of these organisms; but in no instance were the 
appearances revealed by the microscope sufliciently distinct 
to place their identity beyond question. In the case of the 
structures now under notice there can be no doubt of the 
kind; and we are thus furnished with another interesting 
link in the chain of evidence which goes to prove the general 
lithological identity of the chalk with recent deep-sea calca- 
reous deposits. 
The genera of Polycystina met with in the nodular cavi- 
ties are, for the most part, Astromma, Haliomma (both dis- 
* Quart. Journ. Geol. Soc. for Feb. 1880, and Ann. & Mag. Nat. Hist. 
for Feb., March, and July 1881. 
