104 Anniversary Address to the 
species of Trilobites, no fewer than 78; and several genera, 
including Harpes, Bronteus and Proteus, appear for the 
first time in Bohemia. Cephalopoda abound; as many as 
200 species, of which half are Orthocerata, have re- 
warded the collector. Ascoceras, Gomphoceras, and Phrag- 
moceras are the characteristic types. Gasteropods, Lamel- 
libranchs, and Brachiopods are numerous, and there are not 
a few Zoophytes. 
The second or middle stage of Upper Silurian limestones 
presents a decreasing fauna, but at the same time exhibits 
the maximum of Brachiopoda. Bryozoa and Tentaculites 
appear, and Cephalopoda rapidly diminish in numbers. 
Between the third or upper stage of these limestones and 
the last there is a gradual passage, and in these fishes com- 
mence and Brachiopods have become rare. A considerable 
number of species in this division are enumerated as com- 
mon to it and the two last. 
In the uppermost stage of culminating schists the commu- 
nity of species is reduced to two Trilobites, and the entire 
fauna is poverty-stricken. Traces of vegetables indicate some 
considerable changes in the conditions of the sea-bed. 
For years, ever since 1828, paleontologists have dreamt of 
Trilobitic metamorphoses, and some have pronounced defi- 
nitely for, some as definitely against, the probability of the 
Trilobite undergoing changes in the course of its existence 
as an individual. The full discovery and statement of the 
fact was reserved for Barrande in 1849. In the same year 
Mr Salter shewed that the young individuals of Ogygia Port- 
lockii presented 4—7 segments, and finally 8. Milne-Edwards 
and Burmeister, naturalists thoroughly versed in the history 
of living Crustacea, had previously speculated freely from 
analogy on the probability of their transformations. M. 
Barrande, in the work before us, demonstrates a metamor- 
phosis in no fewer than 16 genera and 28 species. The de- 
gree of change is variable; its intensity comparable with 
the phenomenon in existing Crustacea. The successive and 
progressive elaboration of all the elements in the pygidium 
before becoming free and passing into the thorax, holds good 
in all known metamorphosing Trilobites. The number of 
