On the MontiatUporoids of the Cincinnati Group. 127 



an examination of each bone in the skeleton of an unknown ani 

 mal, and if he found a rib which differed sUghtly from another rib, 

 he were to make a new genus for it or coin a new specific name. 

 Perhaps a more analogous instance, however, could be taken from 

 the vegetable kingdom. Let us suppose a branch of a tree to 

 become so perfectly petrified as to retain all the tissues in the same 

 state as when it was alive. Then suppose this branch to be broken 

 into pieces and scattered over the ground. If a person were now 

 to examine a piece from near the small end of the branch, and 

 compare it with one from the larger end, the outside would present 

 the same appearance in each. But a minute microscopical exam- 

 ination would reveal tissues in the piece from the larger end, of a 

 complicated structure, while that from near the smaller end would 

 be much simpler, and probably quite different. There would be 

 sufficient difference to justify making two genera, if the plan adop- 

 ted by Nicholson and Ulrich in studying the Monticuliporoids were 

 adopted.* Let us now see what the internal characters, upon 

 which so much stress has been laid, are. 



First. — Each tube of the corallum always possesses a com- 

 plete wall. In some instances the walls are distinct during the 

 entire growth of the organism, but in others this is not so apparent. 



Second. — The absence of the "mural pores" of Nicholson, or 

 "connecting foramina" of Ulrich, constitutes the main difference 

 between the ramose species of Favositcs and MonticiiUpora. Yet 

 even this distinction does not always seem to hold good. UJrich 

 says that in a special portion of a single specimen he has detected 

 connecting foramina, f Nicholson says :+ . "The typical Monticii- 



*Since the above was written, one of us has found in two separate notes, remarks 

 bearing upon the vahie of internal features in species making, one relating to tlie vaiia- 

 tions in the skeletons ot birds, the other the minute structure of plants. Dr Sliufeldt, 

 writing in Science^ (IX, p. 416, April 1SS7,) savs after referring to certain marked differ- 

 ences which appear in the skulls of birds of the sam<» species, that in thu light of the 

 examples given, "the entire ground may be covered bv saying that in all forms, both 

 vertebrate and invertebr ite. palamn'ological and otherwise, when we come to compare 

 sufficiently extensive series represented by individuals of the same species, we will find 

 in similar structures marked variations, both as regards relative size and form as we 

 pass 1rom one specimen to another, and if extremes be chosen, the differences will be 

 found to he in many cases of verv striking nature." Again in a notice of a recent book 

 by J Felix, '-Die fossilen Holzer West Indiens," the reviewer remarks that to show 

 the little dependence to be placed upon identifying species on the minute structure of the 

 wood bv means of microscopic sections, that from a "|)ersonal examination of over 400 

 living species, belonging to various families, the author concludes that a studv of the his- 

 tological structure alone is not in general sufficient for the identification of genera or 

 species, since, as he says, different species of tlie same genus may differ so extraordin- 

 arily in their structure that, shpuld one have them before him only in a fossil state, they 

 would never be referred to the -ame genus. Again, species of different genera may so 

 much resemble each other, tliat if known only in a condition of fossilization, they would 

 undoubtedly be referred to the same genus." (Botanical Gazette, vnl. XII, pp. 90-91, 

 April 1887). The same remarks would, it seems to us apply equally well to the internal 

 structure of such lowly org'anized forms as the Monticuliporoids. 



+J. C. S. N. H., v. 124. 



|Tabulate Corals, p. 271. 



