Showing papers in "American Midland Naturalist in 1931"

A Devonian Stromatoporoid Reef

Abstract: True reefs-as distinguished from massive beds-formed by stromatoporoids and stromatoporoid detritus have been recorded infrequently. Thus Cumings and Shrock, in their discussion of Niagaran reefs,2 do not stress the importance of these organisms in the building of reefs, even though they describe one reef whose central mass, or "core rock is a breccia or sand of stromatoporoid and other organic fragments, extremely diagenized and reduced to a porous, inchoate, mealy mass." In the Devonian, where stromatoporoids attain their maximum, we find numerois records of coral reefs; but few or none of reefs built by stromatoporoids. An example of this is Grabau's description of coral reefs in the Traverse of Michigan, while he records only worn fragments from reef margilns in which stromatoporoids also are important,3 and mentions no reefs in which stromatoporoids are the dominant organisms.

Niagaran Stromatoporoid Reefs of the Chicago Region

Abstract: The existence of reef structure in the Niagaran (Guelph, Racine) strata of southeastern Wisconsin and northeastern Illinois long has been known. Since Chamberlin's initial descriptions,' however, they generally have been regarded as coral reefs, though a few authors, such as Bannister2 and Alden,3 have regarded them as the result of warping. It is true that some, especially Grabau4 and Cumings and Shrock,5 have called -attention to the presence of other organisms, notably stromatoporoids, in these and in similar reefs in Indiana; but in no case has serious effort been made to appraise the importance of such organisms as the primary builders of the reefs. In 1919, while a student under Dr. J Harlen Bretz, of the University of Chicago, I first examined the more familiar reefs of the Chicago region: those forming the broad, low elevation known as Stony Island and others exposed in quarries at Thornton and McCook Station. Having but recently worked in the Upper Devonian region of north-central Iowa, where coral reefs seemingly are lacking (Vaughan's reference to reefs of Pachyphyllum in that state6 seems to lack basis), but where stromatoporoids are abundant and form thick beds sometimes referred to as reefs, I at once sought evidence of their part in the formation of the Illinois reefs. It was not hard to find; and

Structure and Classification of Certain Cycadofilicinean Roots from the McLeansboro Formation of Illinois

Abstract: It is difficult to identify with certainty unattached Cycadofilicinean roots. Roots generally, because of a common plan of organization, may easily be confused. However, due to the careful researches of Scott (2), Williamson and Scott (3-4), Arbor (1) and others, we now possess such detailed accounts of the structure of some Cycadofilicinean roots as to make their identity known, even when unaccompanied by other structures of the plant. Sections of coal balls from the McLeansboro formation of Illinois, prepared from petrifactions collected by Dr. A. C. Noe, and very kindly turned over to the writer for investigation, show numbers of roots varying in size from approximately half a millimeter to over a centimeter in diameter, and in one instance show a very close developmental series. It is the purpose of this paper to describe the anatomical features of some of these roots and to discuss their classification.

Shepard's Green County Flora. An Unpublished List of Plants of Greene County, Missouri, by Prof. Edward M. Shepard, Springfield, Missouri

Abstract: Sometime during the year 1883, Prof. Shepard, President of Drury College, Springfield, Missouri, made a list of the plants, either known to him from, or collected in, Greene County, Missouri, which he very kindly sent to me to be used in a Flora of Missouri, which I then had in contemplation. This list has never been published, and I now present it, with some notes on the species which Shepard has on his list. This is not a very long list of species, but it contains the names of some species that are very interesting and noteworthy, and on these I have ventured to make some notations. It will be seen that there are many gaps and omissions in this list, mostly of the more common and abundant species, which leads one to assume that Shepard did not attempt to collect, or make notes on, those species. It is also plainly apparent that he did not attempt to collect the carices and grasses, only one species each of these large falmilies is listed, showing that he was not attracted by this group. I am prompted to publish this short list of Greene County plants, that some one more fully prepared will be induced to publish a supplemental list, bringing the list up to date.

Gaudryinella, a New Foraminiferal Genus

Abstract: Test elongate, adventitious; early chambers triserial, latei chambers biserial from a few compact textularian series through a succession of fully mnature chambers that tend toward uniseriality and may in fullest development reach a perfect uniserial stage; aperture verneuiline in initial stage, textularian in earliest biserial chambers, a lairge round or broadly elliptical orifice in full maturity above the base of the final chamber and becoming more and more nearly terminal with advanced age, terminal on late uniser-ial chambers. Holotype, Gaudryinella delrioensis n. sp. In species of Gatdryina the mature biserial chambers are characterized b5y the typical textularian aperture, a low ot moderately high and arched orifice at the base of the septal face and lying on the penultimate chamber. In species of this genus the mature biserial chamber s following the youthful triserial stage are less compact and are characterized by the round aperture that lies above the base of the septal face. Rare senile tests may exhibit one or more uniserial chambers with a round or broadly elliptical and almost terminal opening. Such senile chambers do not necessarily constitute an essential feature of this genus, but it is an expression of inherent potentialities that become the diagnostic character of Clavuvlina, in which the biserial stage is skipped or almost eliminated from the structure through rapid acceleration in its development from its earliest stage to the mature uniserial chambers.

Notes on the Vegetation of Columbia, Mo.

Abstract: The region under consideration extends from Columbia about fifteen miles in all directions. This small area includes formations representative of most types found within the state. In spite of its interest, it has apparently been visited by few collectors. Tracy, in his Flora of Missouri (9), includes many notices of Boone county, which in the main corresponds to the region in question, based upon his own collections and upon those of Galloway. We have very few of these specimens; a number are now in the herbarium of the Mississippi A. & M. College, where Tracy apparently carried them, together with collections by Swallow, Bush, and others. We have in the University herbarium a few specimens by Eggert Broadhead, Favor, and others. The chief botanical study of the region was made by Daniels (2, 3), whose specimens are preserved in the herbarium. He listed 1058 species and 47 varieties in 435 genera. Upon examination of his specimens, however, some of these species prove to rest upon misidentifications, and some others are not represented. Some of the species represented have not been found in rcent years, while others which he did not collect are now frequent. A revised list of the flora has been prepared and recently published (8). Preliminary lists have been published also of the commoner algae (4) and bryophyta (10) Maneval has recently published a list of certain of the fungi (6), and in the fungus herbarium upon which this list is based are many specimens of vascular plants. It is the purpose of these notes to direct attention to some of the interesting features of the flora and to some of the more important changes that have occurred in our understanding of it since Daniels' work was published.