Oil the Monticuliporoids of the Cincinnati Group. 121 



As there must be some rule to apply for the purpose of separ- 

 ating individuals into classes, orders, genera and species, it is 

 necessary to examine a little into this point. When the points of 

 difference are of minor importance, and here, too, individual opin- 

 ion must come in, and the differences are more numerous than 

 the resemblances, a separation of species is justifiable. When pro- 

 minent structural differences present themselves, which are of con. 

 stant occurence, new genera may be made. But when, in a large 

 suite of specimens, small differences, which might well be char- 

 acterized as individual, present themselves; or when, in a few spe- 

 cimens, variations are observed which might have well been individ- 

 ual, then new species should not to be made for a few abnormal 

 forms. For example, when a form presents certain characters 

 which are intermediate between two other previously considered 

 distinct species, it would be better to unite the three into one in- 

 stead of having three separate names. So, too, genera connected 

 by links of this sort should not be kept asunder, but combined 

 under one, the earliest, name. 



Unfortunately this has not been the case in the study of the 

 species of the difficult group of fossils under consideration. Indeed, 

 in one conspicuous case it has been the exact reverse. Species 

 have been made, genera have been formed, when the characters 

 of the specimens were so exactly intermediate between two pre- 

 vious known species or genera, that they were obviously linked 

 together by the new discovery. We are well aA^are that objections 

 have been urged against the union of any two forms presenting 

 even small differences.* Yet in an investigation such as will here 

 be attempted, it will be better to take a broader view of the mean- 

 ing of species, and include under it the forms which do not seem 

 to be anything else than variations in individuals, not yet sufficiently 

 pronounced to be raised to the rank of species. 



All who have written upon the Monticuliporoids have felt and 

 have referred to the difficulties with which they have had to con- 

 tend. 'i"he immense numbers cf specimens seems to have led to 

 wonderful diversity in development, and the difficulty has been in- 

 creased by the very quantity of material. At first the majority of 

 the species of the group were referred to the genus Chateies, Fischer. 

 This was done in 1875 by Dr. Nicholson, in the second volume of 



*As an instance of this in Botany we find the species, Rtibiis J nclicosus credited in 

 Englanrl with abont 75 different forms, all of them having distinct names. (Hooker, 

 i>tuiient's Flora, p. 114/. A somewhat analogous instance is found in Paheontolog^y with 

 Ortliis lynx. 



