36 
Dr. Gregory, on the Post-tertiary 
plete the investigation in the present paper. In the first 
place, the sand is not yet exhausted ; for although I have ex- 
plored about 600 slides of it, new forms are still from time to 
time occurring. Secondly, it has been found impossible to 
finish the study even of the whole of those which I had ob- 
served in it in 1854, and to prepare figures of them. I pro- 
pose, therefore, only to describe and figure, at this time, such 
of the new forms as have been duly studied. This is, no 
doubt, the majority of them ; but it will require a third paper 
to complete the examination, more especially of the smaller 
forms, among which, as well as among those of the larger 
which have not yet occurred entire, much remains to be done. 
Before describing the new forms, I must add to the list of 
known species formerly given the following, many of which 
were accidentally omitted. Others have since occurred to me, 
and a few have been pointed out to me by Mr. Okeden, well 
known as a zealous observer. These I have also myself seen. 
Additional List of known Species. 
235. * Cymbella sinuata, W. G. 
236. Amphora membranacea. 
237. ,, salina. 
238. „ hyaliiia. 
239. Amphiprora paludosa. 
240. Campylodiscus Kalfsii. 
241. Actiiiocyclus undulatiis. 
242. Actinocycliis ? 
243. Actinocycliis diiodenariiis, Sm. 
244. Nitzschia bilobata. 
245. Naviciila Westii. 
246. „ obtusa. 
247. Hennedii. 
248. „ rostrata. 
250. Naviciila Pandura, Breb. (?) 
251. Pinniilaria megaloptera, Ehr. 
252. „ biceps, W. G. 
253. „ linearis, W. G. 
254. „ siibcapitata, W. G. 
255. „ gracillima, W. G. 
256. Pleurosigma distortum. 
257. „ intermedium. 
258. Gomphonema subtile, Ehr. 
259. Orthosira spinosa. 
260. „ mirabilis. 
261. Grammatophora Palfouriana.f 
(See Svnopsis, Vol. II. PI. LXI. 
fig. 383.) 
249. Navicula varians, W. G. (in 
all its forms). 
On this list I would only remark, that the species marked 
W. G. have been lately described by me, as well as Nos. 
248, 251, and 258, the two last as new to Britain ;J that No. 
249, Navicula varians^ has been also fully described by me 
elsewhere :§ that No. 243, Actinocyclus duodenarius, appears 
* These numbers are continued from Part I., in which I gave a list of 
234 species. 
t I have given a figure of this form, as being little known as yet. At 
first it seemed to differ from the form figured by Dr. Greville, the inter- 
rupted vittae being less conspicuous, the striae more so ; but I am now 
satisfied that it is essentially the same form, which varies, however, more 
than was at first supposed. The figure is not numbered, as it is not 
intended for engraving. 
I ' Quarterly Journal of Microscopical Science,' vol. iv., p. 1. 
§ * Trans. Micr. Soc, Quart. Journ. of Micr. Science,' No. X., p. 10, 
Jan. 1855. 
