232 The American Geologist. October, inoi. 
itetal liveliness, and prodnced vigorous "sports" whose very 
vigor was an assurance of continued heredity. 
The next extreme illustration of a biological crisis in the 
palaeozoic rocks is found in the crinoid-swarming- seas of the 
Lower Carboniferous. The whole series of palaeozoic rocks 
afford nowhere such an extraordinary development of crin- 
oidal forms, and while crinoidal limestones are frequent from 
the Calciferous upward, and establish the strong prevalence of 
these organisms, the actual predominence of the Lower Car- 
boniferous fauna excluding cystids and blastids in species, 
is quite unmistakable. 
A compilation from Miller's catalogue affords this striking 
comparison. 
Genera. Species. 
Paleozoic to top of Devonian . . J 76 346 
Lower Carboniferous 56 653 
The same fecundity is shown in another way, by the 
greater number of genera marked by numerous species in 
the Lower Carboniferous over those excelling in species in the 
lower palaeozoics, while in none of the latter is there a com- 
parable abundance to some of the more prolific genera of the 
Carboniferous seas. In the lowtr palaeozoics for instance', 
nine genera only have ten or more species assigned to them 
whereas in the Lower Carboniferous there are seventeen with 
Actinocrinus covering forty-seven species, Barycrinus twenty- 
three, Bafocriiius fifty-two, Cyathocrinus thirty, Dichocriniis 
twentv-seven, Dorycrinus twenty-four, Brctuwerinns, twenty, 
Enpachycrinns thirteen, Plafycrinus sixty-seven, Potcriocrinus 
sixtv, Scaphiocrimis sixty-two, Taxocriiius sixteen, and Zeo- 
eriniis twenty-nine. 
In the lower palaeozoics Dendrocrinns has twenty-seven, 
Eucalyptoerinns twenty, Megistocrinus twelve, Potcriocrinus 
fifteen. 
The impression of great numbers in the crinoidal life in 
the Lower Carboniferous is not relieved by any considera- 
tions of a defective geological record in the lower palaeozoics. 
There is no reason for suspecting that the record has been 
less carefvilly kept in the latter period than in the former. We 
are therefore met by a distinct organic profusion in the palseo- 
crinoids at that geological epoch, and must infer that a con- 
