FORMATION OF NORTHERN GERMANY. 151 
with some forms (Credneria) which we must undoubtedly refer 
to the Dicotyledons. The whole of these last-mentioned pro- 
ductions are probably restricted to the most recent chalk de- 
posits, and are the oldest members hitherto discovered of the 
most highly developed and largest division of the vegetable 
kingdom; which renders them peculiarly interesting. 
The animal kingdom is far more prolific in preserved forms ; 
they are however only such as inhabit the ocean, and the entire 
chalk formation is therefore evidently and almost exclusively a 
marine deposit. 
The Sponges (Seeschwamme), however, which are especially 
numerous in the Hils-conglomerate (lower greensand), and in 
the lower chalk, belong for the greater part to such genera as 
are met with in the oolitic series, and have moreover repre- 
sentatives at the present time. The Scyphie and Siphonie are 
predominant: but the Celoptychie, which are restricted to the 
upper deposits of the chalk, are especially characteristic from 
their perfect development. 
Of Corals, there occurs an almost innumerable host of minute 
Bryozoa, especially in the most recent chalk strata; and several 
genera (Chrysaora, Heteropora, Thalamaropora, &c.) appear to 
have there become extinct. The Zoantharie occur in general 
very sparingly, and even beyond the limits of our district. At 
Maestricht, for instance, where the greatest number of them have 
been found together, they do not appear to have formed large 
masses, as was the case during the deposition of the coral rag. 
The Radiata are likewise very numerous, with many peculiar 
genera; the Hugeniacrinites, Apiocrinites and Pentacrinites here 
occur for the last time, and appear, especially the latter, not to 
differ very much from older species. Marsupites is entirely re- 
stricted to the upper chalk ; Glenotremites to the Hils-conglome- 
rate (lower greensand): Galerites, Schizaster, Micraster and 
Ananchytes, attain to their greatest profusion of species in the 
upper beds of that group; Holaster in the central beds; and 
Galerites there becomes extinct. 
Among the Brachiopode, the so-called Rudiste (Spherulites) 
are most prominent, since they appear to have existed every- 
where, from the period of the lower greensand to that of the 
upper chalk, and the present creation scarcely presents similar 
beings; but the climate of our latitude appears to have been 
less favourable to them, than that of the southern coasts of the 
