IOWA ACADEMY OF SCIENCES. 31 



Iowa. In the same report Professor Hall, not without some hesitation identifies 

 ■another form found abundantly throuijhout the Devonian area in Iowa, with 

 Acerruhd-ia davidsoiii Edwards and Ilaine. This, so far as I have been able to 

 ascertain, was the first time the name had been employed in a work published in 

 America; for although Edwards and Haine's specimens came from near Jefferson- 

 ville, Indiana, the description of Acernilaria davidsoni appeared in the great 

 Monojjraph of the authors, published in France. It should be noted that near 

 Jetfersonvillo, Indiana, there occurs another form which authors, foHowingr the 

 •example of Edwards and Haines, usually refer to Curiihophiilhim riif/osHin Hall. 



The three species mentioned above, as recotfniz°d by everyone who has ever 

 handled them, are somewhat closely related. Dr. Rominger in Geology of Mich- 

 igan, Vol. Ill, page 107, is disposed to regard them all as but varieties of one 

 species. The A cervulnria daridsoni, an it occurs in Iowa, is certainly very sharply 

 •defined from either of the other two, while A. profunda exhibits a very intimate 

 correspondence as to structure with Ci/aihophf/Unn) riigosum from the Falls of the 

 ■Ohio. 



Comparing J. /jroA^u/rt with yl. f/«c/V/.so«( we may note that it differs in the 

 appearance and mode of growth of the corallum, in the greater tendency to inde- 

 pendent growth of corallites, in the size of its corallites, the shape of its calyx, the 

 thicker non-corrugated wall by which the individual corallites are bounded, the 

 almost entire absence of an inner pseudo-wall bounding a central area, and the 

 thinner septa with more numerous and conspicuously developed carina. 



The A. profunda is a much coarser lookmg species than A. davidsoni. Its 

 lower surface is never as smooth and flat as is that of most coralla of the other 

 species from Iowa. This surface is transversed radially by the outer corallites 

 which stand out in strong, transversely wrinkled ridges, sometimes almost entirely 

 free from union with contiguous corallites. All the corallites show a remarkable 

 tendency to independent growth, so that in some specimens a large proportion of 

 the whole number of corallites stand apart from those adjacent on the upper sur- 

 face of its corallum and are individually covered externally with an independent 

 epitheca. In certain modes of preservation the corallites are even separable into 

 wrinkled, polygonal prisms that exactly imitate a very common condition in 

 CjiathophijUum rugosum. 



In the region from which Hall's type comes the corallites of A. profunda are on 

 the average somewhat larger than those of A. dacidsoni. It is true that the 

 corallites of both species vary within very wide limits, and it is therefore quite 

 possible that the superiority in size of A. profunda may not be maintained in all 

 localities. In the Paleontology of Ohio, Vol. II, page 240, Dr. Nicholson describes 

 a form under the name of Acenularia profunda. Hall, that is distinguished among 

 other things by having the corallities smaller than A. davidsoni. 



The shape of the calyx is markedly different in average specimens of the two 

 species. In A. profunda the calyces are separated by relatively thin partitions 

 owing to the manner in which the sides of the cup slope abruptly downward and 

 inward from the margin; the septa are thin and have conspicuous, crowded carina? 

 which are as fully developed near the margin of the calyx as around the central 

 iirea, particularly in respect to which they are in marked contrast with the septa of 

 A. davidsoni. The septa differ still further from those of A. davidsoni in having 

 more of their edges free and in having their edges beautifully denticulated. 

 There is but little thickening of the septa to form a pseuJo-wall around a central 

 area; indeed this feature is in a large proportion of cases wholly wanting. The 

 secondary septa are nearly as long as the primaries inside the central area. 



