On the MoiiticuHporoids of the Cincinnati Group. 119 



from internal characters, and they were illustrated by a profusion 

 of drawings of the internal microscopic structure. Our opinion of 

 this vast array of genera and species and of microsco])ic work of this 

 sort in general, will be given in detail later on in the present paper, 

 but we cannot forbear saying that it is our belief that this work has 

 resulted disastrously to the study of a confessedly difficult class of 

 fossils ; making it more difficult and confusing than ever before, 

 and loading it with a mass of synonyms which of themselves are 

 enough to deter one who should so desire, entering upon the study. 

 The cause of this we believe to be an erroneous method of study, 

 and we ascribe the vast number of species and genera made, to the 

 almost exclusive attention given to microscopic characters. 



The study which has been put upon the MoiiticuHporoids since 

 1 87 1 has resulted in the identification and description of between 

 sixty and seventy-five well characterized species from the rocks of 

 the Cincinnati Group alone. When we consider their abundance 

 in the various strata we need not be surprised at this result. The 

 fossils are so common in many places in the vicinity of Cincinnati 

 as to make up whole layers of rock. In certain places where they 

 have been weathered out of the shale or rock, they can be gath- 

 ered up almost literally by the bushel. While certain forms seem 

 to be well defined and easily separable, others present such pro- 

 tean features as to become puzzling in the extreme. The extent 

 of this group of fossils, the number of individual specimens, and 

 the various forms some of them present, make it a good family in 

 which to study the differentiation of species, and at the same time 

 present one which should teach the palaeontologist to be cautious 

 how he makes new species on insufficient grounds, often mistaking 

 individual for specific variation, and specific for generic distinction. 



Thus at the outset it becomes necessary to determine, as well 

 as may be, what should be regarded as generic and what as spe- 

 cific characters. In the living organic world it is notoriously a 

 matter of the greatest difficulty to draw the line between many 

 genera and many species. Nay, not only do genera seem to merge 

 into one another, but the higher groups, orders, classes, divisions, 

 are separated bysuch indefinite and indistinct boundaries, that it 

 is very difficult, and at times impossible, to draw the line between 

 them. If this be so with living forms, where advantage can be 

 taken of accurate investigation and examination of extensive suites 

 of perfect specimens, how much more caution should be exercised 

 when dealing with fossils, which are so generally found in limited 



