16 PROCEEDINGS OF THE ACADEMY OF 



After a careful comparison of a series of good specimens, showing clearly 

 both sides, of the fossil on which Dr. Prout proposed to found his genus Septopora 

 (S. Cestriensis, Prout), from the original locality in the Chester limestone of 

 the Lower Carboniferous, with an equally well preserved series of the Coal- 

 measure fossil mentioned above, that has been referred to S. virgulacea, we find 

 that they not only agree exactly in all generic characters, but that we have, up 

 to this time, been entirely unable to discover any specific differences. We ob- 

 serve, it is true, among the Coal-measure specimens, some differences in the 

 greater or less size, and irregularity of divergence of the branches, and conse- 

 quent differences in the sizes and forms of the fenestrules ; but the same dif- 

 ferences are also observable among the specimens from the Chester beds, so 

 that if we were to regard these as specific differences, we would have to admit 

 several species to be common to the two horizons, instead of only one. 



We have for a long time been aware of the fact that the form that has been 

 referred to S. virgulacea, from the Kansas and Nebraska rocks, not only ranges 

 through the beds included by some as lower Permian in Kansas, but that it 

 has an extensive vertical and geographical range in the admitted Coal-meas- 

 ures of these States and Iowa. We are also now prepared to show that it 

 not only ranges through the whole of the Coal-measures of Illinois, but that, 

 as above stated, specimens beyond all doubt belonging to the same genus, and, 

 as we believe, to the very same species, occur both in the St. Louis and Chester 

 beds of the Lower Carboniferous limestone series. We were slow to adopt 

 the conclusion thut the specimens from these different horizons are really spe- 

 cifically identical, because we have so often, in such cases, on examining bet- 

 ter collections than those first obtained, succeeded in finding differences not 

 previously supposed to exist. In this instance, however, as well as occasion- 

 ally in others, we have, as already mentioned, found the specimens to agree 

 exactly in apparently all of their specific characters. 



In regard to the generic relations of this fossil to the genus Synocladia, as 

 typified by the common European Permian true S. virgulacea, there may be differ 

 ences of opinion between some of those who draw very exact distinctions be- 

 tween genera, and others who give them greater latitude. That they really 

 belong to the same genus, however, we can scarcely entertain any doubts, 

 though it must be admitted that they are certainly distinguished on very 

 nearly the same kind and degree of differences that distinguish Feneslella from 

 Polypora. 



It is a little remarkable that Dr. Prout, who made an especial study of the 

 palaeozoic Polgzoa, should have failed to notice the very close relations be- 

 tween his Septopora and Synocladia, at the same time that he assigned to the 

 former almost exactly the same characters mentioned by Prof. King in describ- 

 ing his genus Synocladia. This identity of generic characters in these two 

 species will be better understood by comparing the original generic descrip- 

 tions of these forms as given by Prof. King and Dr. Prout, making, of course, 

 some allowance for differences of terminology. Prof. King's description of 

 Synocladia (see Brit. Permian Foss. p. 38) reads as follows : 



"A foliaceous or frondiferous infundibuliform Fenestetlidia. Fronds con- 

 sisting of numerous connecting stems or ribs. Stems bifurcating; radiating 

 from a small root ; running parallel to, and at short distances from each other, 

 on one plane; and giving off bilaterally numerous short, simple branches 

 [dissepiment], of which opposite pairs conjoin midway between its stems, 

 arcuately or at an ascending angle. Branches occasionally modified into 

 stems. Cellules on the inner or upper surface of the fronds; on both stem3 

 and branches; imbricated, and distributed in longitudinal series. Series of 

 cellules separated from each other by a dividing ridge. (?)Gemmuliferou8 

 vesicles on the dividing ridge." 



He farther adds that this genus differs from the allied genera, in the arching 

 and celluliferous character of its connecting branches, or dissepime/its, and the fact 

 that they are sometimes developed into intermediate radiating branches or stems. It 



[March, 



