396 
THE GEOLOGIST- 
AMMONITES. 
Section I. — Back with entire keel. 
1. Arietes (ram -horn). 
2. Falciferi (sickle-beai'ing). 
3. Cristati (crested). 
Section II. — Back crenated. 
4. Amalthei. 
5. Rhotomagenses. 
Section III. — Back sharp. 
6. Disci (quoit-shape). 
Section TV. — Back channelled. 
7. Dcntati (toothed). 
Section V. — Back squared. 
8. Armati (armed). 
9. Cwpricomi (gort-hom). 
10. Ornati (ornamented). 
Section VI. — Back round, = convex. 
11. HeterophylU (odd-leaf). 
12. LigpAi (constricted). 
13. Annulati (ringed). 
14. Coronati (coronate). 
15. Fimhriati (bordered). 
16. Cassiani [complex lobes]. 
(To be continued.) 
RESEARCHES ON P S E U D 0 M 0 R P H S . 
By M. Delesse. 
Translated from the " Annales des Mines"* by H. C. Salmon, F.G.S. 
Metamorphism, considered in its widest generality, comprises all tlie 
modifications wliicli mineral substances undergo. It is naturally 
divisible into parts, according as its objects bear upon minerals or 
upon rocks. It is the metamorphism of minerals which I propose 
studying in this notice, and I shall describe it under the name of 
pseudomorphism. But as certain associations of minerals present all 
the appearances of pseudomorphism, with which they have been 
often confounded, it is necessary, in the first place, to consider these 
specially. 
Wc know that, notwithstanding their great variety, the rocks 
* Vol. xvi., p. 317 : 6th livi-aison. 1859. 
