164 Professor Elu'Gnl)erg' on the Microscojtlc AnbiHth 



covered that they contain the microscopic animalcules of the 

 chalk of northern and southern Europe. 



It appears that the following conclusions may be deduced 

 in reference to the whole subject. 



1. Many, probably all the chalk rocks of Europe, are the 

 2iroduct of microscopic, spiral, coralline animalcules, which, for 

 the most part, are quite invisible to the naked eye, some pro- 

 vided with calcareous, and others wath siliceous shells, and 

 which are from l-24th to l-288th of a line in size. 



2. The chalk rocks of Southern and Northern Europe con- 

 tain, among their component parts, many perfectly similar cal- 

 careous animals, of which the most remarkable are, Textularia 

 globiilosa, Textularia aciculata, and JRotalia globulosa. Fo- 

 talla ornata, Glahigerina huUokhs (D'Orbigny), Planitlina tur- 

 (jida and sictda, Bosalina glubidaris, Textularia aspera^ hrevis, 

 dilatata, and italica, together with Escharella Scutellaria (Es- 

 chara scutellaris, Soldani), are the remaining characteristic 

 forms of the chalk, to which are also to be added some of the 

 species mentioned hy D"Oi'l>igny, Nilsson, and Pusch, and the 

 Spirulina of Lord Northampton. 



3. The cretaceous districts bordering the Mediterranean 

 in Sicily, Barbary, and Greece, and generally regarded as ter- 

 tiary deposits, are therefore, judging from their organisms, to 

 be considered as chalk or secondary rocks ; and the nummu- 

 lite limestone of Egypt is to be viewed in the same light. 



4. The chalk strata of southern Europe, round the basin 

 of the Mediterranean, are distinguished from those of the 

 north and -east of Europe by their better preserved chalk ani- 

 malcules, and by the smaller number of theu* elliptical grams ; 

 and the converse holds good. 



5. The chalk strata of the south of Europe contain few or 

 no flints. Those of the north present many extremely regu- 

 lar hoi'izontal beds, which are often only fropi one to six feet 

 separated from one another. This featm-e was previously well 

 known ; but, what seems new and remarkable, is the observa- 

 tion made by the author, that in the chalk strata of northern 

 Europe, hitherto no marls of infusoxy animals have been found 

 like those which alternate with the chalk in sixch prodigious 

 abundance in Sicily, Oran, and Greece. A comparison of the 



