350 - PROF. EHRENBERG ON ANIMALS OF THE CHALK 
Favus, one of the characteristic forms first observed living near 
Cuxhaven, and which is represented on Plate VIII.; Eunotia gra- 
nulata and Cocconema lanceolatum, common recent forms of 
brackish and fresh waters, and Biddulphia pulchella, a widely- 
diffused true marine form of the present day; also Navicula qua- 
drifasciata, norwegica, and Entomon, together with Coscinodiscus 
Oculus Iridis, all species which I had found living in the waters 
of the Baltic and North Sea. Besides these ten bodies, only 
two of which had been observed in tertiary strata (they both 
also occur at Bilin), there were several other hitherto unknown 
minute shells, of which one, Haliomma radians, is of especial 
interest. In a bottle-full of turbid sea-water, obtained a few 
days ago from Cuxhaven, I discovered this form among many 
living chalk animals of species already described; and at the 
same time, in a living state, Planulina (Rotalia) ocellata, which 
had hitherto occurred only in the true white chalk and the 
chalk marls. 
Thus, then, of the six peculiar genera of siliceous-shelled ani- 
mals of the chalk formerly announced to the Academy, the 
genera Actinocyclus, Coscinodiscus, Dictyocha, and Haliomma, 
have been proved, at least as regards several species, to belong 
to the present world; and it is scarcely probable that the two 
genera Cornutella and Lithocampe will remain behind. The num- 
ber of recent microscopic animals of the chalk, which in my 
first communication comprised thirteen species, amounts at pre- 
sent, according to observation, to fifty-seven species. 
IX. Conspectus of all the Forms belonging to the present world 
identical with those of the Chalk Formation. 
As in the commencement of this memoir only those observa- 
tions respecting the occurrence of recent animals in the chalk 
were mentioned, which, notwithstanding the doubts cast upon 
them by the researches of Deshayes and Lyell in 1831, have 
again been maintained, it appears at present desirable to bring 
into a general view all the recent data which have come to my 
knowledge, more in detail than they have hitherto been, and to 
add to them my own latest observations. 
M. Defrance in France, and Dr. Fitton in England, observed 
contemporaneously in 1824, that in fossil strata beneath the 
chalk there still occurred some recent species of animals. De- 
france made known as such a Trochus and two or three Tere- 
bratule, among which was the Terebratula vitrea of the chalk 
