NATURAL SCIENCES OF PHILADELPHIA. 17 



will also be observed that he does not mention the number of row Hales 



or pores in each radial branch or stem, in his generic description, though be 

 does so in describing the species; from which it is evident that he did nol 

 gard that as a generic character, and that he would have considered the 

 American type as belonging to another species of the same genus. 



For comparison with the above, we give below Dr. Prout's description of his 

 proposed genus Septopora, from the Transactions of the Acad. Sci. of St. 

 Louis, vol. I. p. 448 : 



"Bryozoum a fan-like expansion, with longitudinal ribs [stems of Prof. 

 King], irregular in size, radiating from a centre, branching and occasionally 

 anastomosing, having two lines of pores, one on each side of a tuberculated 

 midrib* Dissepiments forming arches or more or less angular, dividing the 

 Bryozoum into quadrangular, round, semi-lunar, or rhombic fenestrules ; each 

 dissepiment supporting from one to four irregular lines of cell-pores ; reverse 

 smooth when worn, but more or less tubercled when perfect."! 



He adds that, "though in its general features it resembles Fenestella, it dif- 

 fers in a marked degree by its celluliferous dissepiments." This, it will be 

 observed, together with the arched, or angulated character of its dissepiments, and 

 the fact that they sometimes give origin to intermediate branches, or sterms, as Prof. 

 King terms them, were exactly the characters mentioned by the latter author 

 as distinguishing Synocladia from other allied Fcnestellidx. Although Dr. 

 Prout does not mention the character of the angulated dissepiments giving 

 off intermediate branches, his figure 2 a, pi. 18, of the St. Louis transactions 

 cited, distinctly shows it, and it is even more strongly defined in specimens 

 now before us, from the original locality, and identified by Dr. Prout himself. 

 It is also worthy of note, that Dr. Prout's enlarged figures, 2 b and 2 c, of the 

 plate above cited, do not give a correct idea of this fossil, as may be seen by 

 comparison with his own description. Figure 2 c, for instance, represents the 

 fenestrules proportionally much too small, and the dissepiments too thick 

 and not in the slightest degree "forming arches, or more or less angular." 

 Figure 2 b also fails to show this arching or bending upward of the dissepi- 

 ments, and the "tubercles" or vesicles on the midrib, which characters are as 

 strongly defined in the Chester and Coal-measure specimens as in Prof. King's 

 figures of the typical S. virgulacea. Some portions of the celluliferous surface 

 near the base of the frond might be selected from some specimens that would 

 nearly agree with these figures given by Dr. Prout, but this is far from the 

 general character of the fossil farther up, where the branches are more diverg- 

 ing, so as to form larger fenestrules. 



The question respecting the relations of these Western specimens, from the 

 several horizons mentioned, to each other, and to the European Permian Syno- 

 cladia virgulacea, is, for other reasons, one of more interest and importance 

 than the mere difference or identity of particular fossils, since it involves the 

 question of the duration in time, and the consequent geological range, of one 

 of the most important of the types that have been appealed to as evidence 

 that the Permian should be carried down in Kansas and Nebraska, so as to 

 include several hundred feet of rocks regarded by us and others as belonging 

 to the true Coal-measures. Whether we regard this fossil as being specifi- 

 cally identical with Synocladia virgulacea (which we do not admit), or view it 

 as a distinct species of the same genus, it is now evident that it can no longer 

 be regarded as properly a Permian type; for, even if it could be shown to be 

 only a variety of S. virgulacea, it would still b a, form unknown in the Permian 

 of Europe ; while here it is, as above shown, not only one of our most abun- 

 dant Coal-measure types, but one that began its existence during the deposi- 

 tion of lower Carboniferous or Mountain limestone series. 



* The midrib mentioned here is the "dividing ridge" of Prof. King, and the "tubercles" 

 on it are the "(?jgemmuliferous vesicles" of Prof. King. 



t It is minutely striated in perfect specimens, as we know from examination of typical 

 examples from the original locality. 



1870.] 2 



