= i= + oS el ¥ * = pati # —— A ‘ — FZ, es . Ae — oe > Sey Sa : > SSS = * 52 ee = 4 a = p= Wy = : “B= Sp = =| SSS: Peon f YAS K B y “a = =" ies ss we i c= AS di = OD ey —" | = ie es. E SS CaS a = ae N =. => = —*>_ SSeS 7 Bai. = = % EN A —— | ce 4 < Se S| ms if | 3 : £ State geologist. -; a | STRAIN es 0) Vy ‘i President THE Hon. Davin L. KIEHLE, - - : : : - Recording Secretary PRESIDENT CYRUS NORTHROP, JosepH E. Warg, (Address care of St. Anthony Falls Bank, Minneapolis, ) The Executive Committee. THe Hon. JOHN S. PILLSBURY, Chairman. PRESIDENT CyRUS NORTHROP, THe Hon. WILLIAM LIGGETT. Corresponding Secretary Treasurer — Geological and Natural History Survey of Minnesota 0 ef | ACY a 1 “geen ina Res ation! SECON rot aD ad ae IES GEOLOGICAL AND NATURAL HISTORY SURVEY OF MINNESOTA. N-HWINCHELL, STATE GEOLOGIST. Scale: 42 miles to an inch. fa Probable Cretaceous Areas fea] Lower Silurian Areas yLa Crosse JULIUS BIEN B ¢ THE GEOLOGICAL AND NATURAL HISTORY SURVEY OF MINNESOTA. N. H. WINCHELL, Strate GEOLOGIST. 1885 —1892. THE GEOLOGY OF MINNESOTA. VO. Il, PARLE. OF THBP TN A REPORT. PALEONTOLOGY. By Lro LESQUEREUX, CHARLES SCHUCHERT, ANTHONY WOODWARD, EDWARD O. ULRICH, BENJAMIN W. THOMAS, NEwtTon H. WINCHELL. SUBMITTED NOV. 30, 1891, AND PUBLISHED UNDER THE DIRECTION OF HON. FREDERICK P. BROWN, SECRETARY OF STATE. ILLUSTRATED BY FORTY-ONE PLATES AND THIRTY-FOUR FIGURES. MINNEAPOLIS, MINN. HARRISON & SMITH, STATE PRINTERS. 1895. ~ ~ rt ay OP eo) ve gt See rs ‘ ~ a \ > «Ly = See. oe t *, J 4 7 eaten : 4 rd . - ’ « ee : oad 3 ss ~ aft s ‘ ‘ “4 az yi fi ‘<= ‘ * 4 « ‘ - f “ = rm s ‘es maa Li vi, ‘Entered according to act of Congress in the office of the Librarian of cree at Washington, i in the year 1895, by Hon. Albert. Berg, Secretary of State, on behalf of the people of Minnesota. ' " 3 5 - > ? 7 > re ¢ y ' - $4 ~ n ft: +, fe < P< , ad vh * j aes s =! ~ o f >? , pS y ik it 7 5 ; ‘ t» - oo, & : ; a > “! ‘ I t i = , H <= J * ’ ees 2 t = ’ item 5 “2 Z 7s T-) ‘ & ‘ \ z at 4 . a ¢ \ . s : - . i ‘ . - ‘ ’ ‘ ‘ i~ z 4 “a ‘é . ote < / ‘ ~ ” ? ‘ ¥ ‘ - J . 5 ‘ ms TABLE OF CONTENTS. Letter of Transmittal by the STATE GEOLOGIST. Letter of PRESIDENT JOHN S. PiLusBuRY of the Board of Regents. INTRODUCTION. Historical sketch of investigation of the Lower Silurian in the Upper Mississippi Valley. Page. BYANey Esa WiEN CHG Gunde Hrs Oy WiRIC Hie tees. tolesslcray crap stersie ataloraitatvavel= puvorel sieves eaveterst tee evens roses) ole ret ix to liii CHAPTER I. Cretaceous fossil plants from Minnesota. By LEO LESQUEREUX. ............0e ener eee ceeenees 1to 22 CHAPTER Il. The microscopical fauna of the Cretaceous in Minnesota, with additions from Nebraska and Illinois. By ANTHONY WOODWARD and BENJAMIN W. THOMAG..................e005- 23 to 52 Note on other Cretaceous fossils in Minnesota. By N. H. WINCHELL............. 0.00.00 eee eee 538 to 55 CHAPTER III. Sponges, Graptolites and Corals from the Lower Silurian in Minnesota. By N. H. WINcHELL ANCE CHAR EMSs S CHU CO ELER Ds atscy-cersevelaete ters aioe nae sles Slee toke Neislans flee elelavel Sido) crake ohensje leet ereeiere 55 to 59 CHAPTER IV. On Lower Silurian Bryozoa of Minnesota. By B. O. UbRICH.............cceccceeeec cece ecsseees 96 to 332 CHAPTER V. The Lower Silurian Brachiopoda of Minnesota. By N. H. WINCHELL and CHARLES SCHUCHERT. 333 to 474 IG So andoreoatodcGn doolbendocdod conoea OhD UDOOeordE Can Snannce aCe nt aoa cca ho cSepedtauntoracrH ses lvii to xxv Map showinp bherarearo phe iow era sulunlamen ois COTS The Blue limestone is considered as ‘‘undoubtedly the equivaleut of the Blue lime- stone so abundantly developed at Cincinnati.” The Buff limestone is below the Blue. J. G. Pericival 1855. Annual report on the Geological Survey of the state of Wisconsin. By JAMES G. PERCIVAL; Madison, 1855; pp: 1-101. The entire report is given to economic geology and the lead region is the only part of the state described. The series of rocks found here is as follows: > IoD XXVIl] THE PALEONTOLOGY OF MINNESOTA. “J. The Mound strata, consisting of three distinct beds of limestone; the upper, middle and lower. 2. A bed of Blue shale, separating the Mound strata from the next lower limestone series. 3. The Upper Magnesian of Owen, also consisting of three distinct beds. 4. The Blue limestone, including the Blue and Buff limestones of Owen (Ist Rep.,) also presenting three distinct beds. 5. The Upper Sand- stone. 6. The Lower Magnesian of Owen. * * * * 7, The Lower Sandstone.” The Blue shale here individualized, being the ‘‘Nucula bed” of Daniels, became sub- sequently known as the Maquoketa shale. Percival calls attention to the small fossils, but seems to have no idea, as yet, of the equivalence of this bed with the Hudson River of New York. He gives it a distinct place in the lead region, viz., between the Mound limestone (the Coralline limestone of Owen) and the Upper Magnesian limestone. The term ‘‘Blue limestone” is here made to include the Blue and the Buff of Owen. J. G. Percival. 1856. Annual report of the Geological Survey of the state of Wisconsin. By J. G. PER- CIVAL; Madison, 1856; pp. 1-111. This is acontinuation cf the descriptions of Dr. Percival’s first report. He gives more details of the lithology of the several formations, spoken of in the other report, and the characteristics of the minor divisions of each. He mentions shells of the genus Leptcena as being characterastic of the ‘‘Blue limestone.” Below the coralline beds of Dr. Owen he de- scribes a blue shale ‘‘underlying the mound limestone, and thus immediately above the upper magnesian,’’(p. 14). This he describes at numerous points in the Mississippi valley, and affirms that it occurs in the eastern part of the state, describing it at several points on the narrow peninsula which forms the eastern side of Green bay. This seems to have been the first published identification of this shale with the Hudson River rocks of the east shore of Green bay. James Hall. 1858. Report of the Geological Survey of the state of Iowa, embracing the results of investigations made during portions of the years 1855-56, and 57. By JAMES Haut and J. D. Watney. Vol. I, parts 1 and 2 (in two volumes), 1858. In giving a general review of the formations (Chapter 111) Prof. Hall states that the ‘“Trenton limestone with the subordinate beds of the Birdseye and Black River limestones, preserve, at several points above Dubuque, upon Turkey river and other places in Iowa, at Platteville and Mineral Point in Wisconsin, at the falls of St. Anthony and at St. Paul in Minnesota, ina greater or less degree, their distinctness of character and position.” In a section at Pike’s hill opposite the mouth of the Wisconsin river he includes the Trenton and Birdseye limestones between the Galena and the ‘‘magnesian beds below,” giving them a total thickness of 75 feet. In other words, he excludes both Trenton and Birdseye from that stratum of the Lower Silurian which later became known as the Buff limestone, and which still later came to be considered exclusively as the Trenton. With these he also must necessarily have excluded the Black River limestone. In asection at Clayton (p. 56) he describes the Galena as alternating with the Trenton. The total thickness, between the St. Peter sandstone and the Galena, he found at Guttenburg to be about 100 feet, and in HISTORICAL SKETCH. XX1x the same place he mentions Receptaculites over 50 feet below the base of the Galena lime stone. The same occurs at Elkader mills. The Galena is estimated, at Hlkader mills, as 130 or 140 feet thick, and at Dubuque as 200 or 250 feet thick. ‘‘From all the sections measured it is very certain that the Galena limestone gradually thins out to the north and northwest, and at the same time loses very much the characteristic features which distinguish it in the productive lead region.” The uppermost beds at Elkader mills are said to be ‘‘black on fresh fracture, weathering to light gray or drab,” an evenly bedded limestone with shaly partings. The Hudson River group, which had been described by Percival in Wisconsin under the name of ‘‘Blue shale,” was recognized by Hall in Iowa, occupying a slope usually without exposure of rock, situated between the Galena limestone and the magnesian limestone which forms the capping of numerous mounds in the northeastern part of Iowa. These beds were found to be characterized by great numbers of small orthoceratites and Nucula. The basal member is a black slate ‘‘not unlike the Utica slate,” and contains two species of Lingula, one much larger than the other. The total thickness of these beds is not more than 60 feet. ‘‘The term ‘Blue limestone’ was originally applied in the Ohio geological reports to the shales and limestones of the Hudson River group as developed in the neighborhood of Cincinnati, and these were formerly supposed to be the continuation of the Trenton limestone of New York.” The fossils described in Part Il of this report are Devonian and Carboniferous. J. D. Whitney. _ 1858. In the same volume as the last noted the chapter on « Chemistry and Econom- ical Geology” is by professor J. D. WHirNEy. He reviews the geological succession in lowa. The term ‘‘ Blue limestone” here is made the equivalent of the Trenton, including all the strata from the St. Peter to the Galena, and the Buff limestone is a subordinate member at the bottom, which for convienence of description could be distinguished “from the Blue limestone proper.” The Buff varies from 15 feet to 20 feet in thickness, and the Blue proper from 70 feet to 80 feet. In the discussion of the stratigraphy and the chemical composition it is not plain whether the author speaks, generally, of the Blue limestone or of the ‘‘ Blue limestone proper.” The ‘‘glass rock” characters are common near the bottom. This is a nearly pure carbonate of lime, fine-grained, imperfectly crystalline, easily breaking into cuboidal blocks with a smooth, often conchoidal fracture. The passage from the Trenton to the Galena is by a series of alternations of purely calcareous and calcareo- magnesian layers. The greatest thickness of the Galena is at Dubuque, 250 feet, and from that point it seems to thin out in all directions. Thisis a dolomyte, and resembles the Lower Magne- ian limestone. Toward the top it becomes shaly, and gradually passes into the Hudson River shales. The central portion is massive, coarsely crystalline, with cavities that appear on weathering, with chert and other siliceous impurities, and the lower beds become Xxx THE PALEONTOLOGY OF MINNESOTA. less dolomitic, with alternations of shale and of Blue limestone. Receptaculites is confined to the Galena limestone, within the mineral district, but further north, as on Turkey and Upper Iowa rivers, it is abundantly scattered through the shaly beds of the Blue. The Hudson River shales contain from one-tenth to one-fifth of their weight of carbon- aceous matter, ‘‘The Hudson River shales, with the closely allied Hudson River slates, seem to have been deposited under conditions somewhat resembling those under which the true coal-bearing rocks were accumulated.” Henry D. Rogers. 1858. The Geology of Pennsylvania, a government survey. By HmeNRyY DARWIN Rogers. Vol. II, Philadelphia, 1858. In the discussion of the history of the Matinal period (p. 784),the author makes a sugges- tion, carried out more fully by Mr. C. D. Walcott in 1879, that the Galena limestone oc- cupies nearly the same stratigraphic position as the Utica slate of New York. He adds: “But whether it was produced in the same age with that deposit, or in that next before ‘it, or, again, in that next after it, we are without the means, for the present at least, of ascertaining, since the black slate and it nowhere occur in the same districts, nor even approach each other by a wide geograph- icalinterval. * * * * * * The very marked transition between the Matinal argillaceous limestone [Trenton] and this lead-bearing rock, in regard to their organic remains, strongly intimates that some important physical change took place in the interval.” It is evident, from the last remark, that Prof. Rogers considered, at that date, the lead-bearing rock as a part of the Cliff limestone, asstated by Hall. This idea, however, had been corrected prior to the publication of the Pennsylvania report, largely through the agency of Prof. Hall, in the report of Foster and Whitney (1851), though perhaps not prior to the time at which Prof. Rogers wrote the above words. At any rate, as a matter of fact, there is no great contrast in their organic remains, between the Trenton limestone and the lead-bearing rock. The contrast which Prof. Rogers refers to as obtaining between the Matinal limestone and the Cliff (Niagara) to which the lead-bearing rock had been referred by Owen and Hall, as those formations are represented in New York and Pennsylvania, is that which is now well known at the top of the Galena. Edward Daniels. 1858. Annual Report of the Geological Survey of the State of Wisconsin, for the year ending Dec. 31, 1857. By Pror. E. DANIELS, Madison, 1858. Pamphlet of 62 pages. The author, in describing the iron ore at Iron ridge, Dodge county, reverts to the fact that he made the discovery of the ‘‘Blue shale” in 1851, and described it as ‘‘Nucula shale” in 1853. He evidently is in error when he states (p. 13) that this stratum had been “recognized by Prof. Hall in Foster and Whitney's report on the Lake Superior Land district as belonging to the Hudson River group,” since it was only in the Green bay region, in the eastern part of the state, that Prof. Hall recognized the Hudson River formation, and there was then no known connection of the Blue shale of the Mississippi valley with the Hudson River strata seen in the region of Green bay. This connection was pointed out by Dr. Percival. HISTORICAL SKETCH. KEK Henry Youle Hind. 1859. Reports of progress: together with a preliminary and general report on the Assiniboine and Saskatchewan exploring expedition, made under instructions from the Pro- vincial Secretary, Canada. By HENRY YOULE Hinp, M. A., Professor of Chemistry and Geology in the University of Trinity College. Toronto, 4to, with maps and plates, pp. 201, 1859. This valuable report, which is too often ignored by later travelers in making their reports on the region, gives definite information concerning the paleontology of the rocks on the western side of lake Winnipeg, accompanied by detailed sections of the strata. ‘Nearly the whole length of the western coast of lake Winnipeg is composed of lime- stones, sandstones and shales of Silurian age.” These are assigned to the Chazy, Birds- eye, Trenton and Hudson River formations. The Chazy is a crumbling sandrock (the St. Peter sandstone of Owen). The Hudson River group is seen in cliffs 25 feet high at Stony Fort, on the Red river. He quotes the description of Owen who visited and reported on the Red River settlements in his final report on Iowa, Wisconsin and Minnesota, (p 181) in 1852. The fossils reported by Owen, from Lower Fort Garry are: Favosites basaltica, Coscinipora sulcata, hemispherical masses of Syringopora, Chztetes lycoperdon, a Conularia, a small, beautiful undetermined species of Pleurorhynchus, Ormoceras bron- gniarti, Pleurotomaria lenticularis (?), Leptana alternata, Leptana plano-convexa (?), Calymene senaria, and several specimens of the shield of Illeenus crassicauda. ‘Many of theseare identically the same fossils which occur in the lower part of Formation 3 in Wis. consin and Towa, in the Blue limestones of Indiana, Ohio, Kentucky and Tennessee, and also in the Lower Silurian of Europe.” In this report Mr. E. Billings, paleontologist of the Canadian survey, contributes a chapter on the paleozoic fossils, describing two new Silurian species, viz,, Modiolopsis parviuscula, and Orthoceras simpsoni. These and the other fossils named by him are considered sufficient to show that the beds containing them are probably about the age of the Chazy and Black River limestones. James Hail. 1861. Report of the Superintendent of the Geological Survey of Wisconsin, exhibiting the progress of the work, Jan. 1, 1861. By JAMES Hau; Madison, 1861. This report is devoted almost entirely to the description of fossils of which the follow- ing are from the Trenton, Galena and Hudson River:— Receptaculites oweni Hall. “In the Galena limestone of Wisconsin, northern Illinois and the eastern part of Iowa this fossil is everywhere present and is the most marked and characteristic form in the rock.” Receptaculites iowene Owen. Galena limestone. Receptaculites fungosum Hall, Galena limestone. Receptaculites globulare Hall. Galena limestone. Graptolithus (Diplograptus) peosta Hall. Hudson River shales. Dictyonema neenah Hall. Trenton limestone. Buthograptus laxus, n. sp. Trenton limestone. Tellinomya inflata, n. sp. Trenton limestone. Tellinomya aita, n. sp. Trenton limestone. XXXIl1 THE PALEONTOLOGY OF MINNESOTA. Tellinomya ventricosa, n. sp. Trenton limestone. Tellinomya ovata, n. sp. Trenton limestone. Cypricardites rotunda, n. sp. Trenton (Buff) limestone. Cypricardites niota, n. sp. Trenton (Buff) limestone. Cypricardites rectirostra, n. sp. Trenton (Buff) limestone. Modiolopsis planus, n. sp. Trenton (Buff) limestone. Modiolopsis? superbus. n. sp. Trenton (Bluff) limestone. Ambonychia lamellosa, n. sp. Trenton limestone. Ambonychia planistriata, n. sp. Trenton limestone. Ambonychia erecta, n. sp. Trenton limestone. Ambonychia attenuata, n. sp. Trenton (Buff) limestone. Pleurotomaria niota, n. sp. Trenton (Buff) limestone. Pleurotomaria nasoni n. sp. Trenton (Buff) limestone. Pleurotomaria semele, n. sp. Shales above Galena limestone. Maclurea bigsbyi, n. sp. Trenton (Buff) limestone. Ecculiomphalus undulatus, n.sp. Treuton (Buff) limestone. Lituites undatus var., occidentalis n. sp. Trenton (Buff) limestone. Lituites robertsoni, n. sp. Trenton (Buff) limestone. Cyrtoceras whitneyi, n. sp. Shales above Galena limestone. Cyrtoceras neleum, n. sp. Trenton (Buff) limestone. Cyrtoceras engium, n. sp. Trenton (Buff) limestone. Crytoceras loculosum, n. sp. Trenton limestone. Onoceras abruptum, n.sp. Trenton limestone. Onoceras plebeium, n. sp. Trenton (Buff) limestone. Onoceras pandion, n.sp. Trenton(Buff) limestone. Onoceras lyceum, n. sp. Trenton (Buff) limestone. Onoceras alceum, n. sp. Trenton (Buff) limestone. Orthoceras gregarium, 0. sp. Shales above Galena limestone. Orthoceras planoconvexum, n. sp. Trenton (Buff) limestone. Gonioceras occidentalis, n. sp. Vrenton limestone. Tilenus taurus, n. sp. Trenton (Buff) limestone. Calymene mammilata, n. sp.Shales above Galena limestone. C. L. Anderson and Thomas Clark. 1861. Report on Geology and a plan for a Geological Survey. By ANDERSON and CLARK; addressed to the Legislature of Minnesota, Jan. 25, 1861. In this report Mr. Anderson follows Dr, Owen. denominating the limstones at St. Paul, and the falls of St. Anthony, ‘‘Shell or Blue limestone.” “Tts distinguishing fossil is Leptzna, some fifteen species of which occur in it. Orthoceratites are exceedingly common, and the species numerous. Some of them are of enormous size, measuring nine or ten feet in length.” He remarks that the line distinguishing this from the ‘‘ Upper Magnesian limestone ” is difficult to find, and that Dr. Owen classed them together. We have seen, on the con- trary, that Dr. Owen, in his final report, considered the Upper Magnesian limestone, or the the lead-bearing portion of it to which the the term was latterly confined, as the equivalent of the Utica slate and the Hudson River group, and that he parallelized the ‘Shell or Blue limestone” with the Trenton. As to the Galena limestone, these authors are inclined to consider it almost if not entirely wanting in Minnesota, but suggest that it may exist in some of the high bluffs in the middle southern counties. . James Hall. 1862. Report on the Geological Survey of the State of Wisconsin, Vol. 1, 4to, 1892, JAMES Hau and J. D. Wuirnrey. By authority of the Legislature of Wisconsin. HISTORICAL SKETCH. XXXlil Chapter IX is devoted to the paleontology of Wisconsin. After a short description of the conditions of preservation of fossils in the various formations, the chapter contains a cata- logue of the paleozoic fossils of Wisconsin, including those described by Owen, Conrad, Hall, and others, from localities within the state, and those which had been identified with species described from other states, giving references to original descriptions and to other publications. This catalogue also includes the names of fossils identified in the state on authority of I. A. Lapham. Localities are generally not mentioned. Fossils are simply referred to their formation, and to the places where originally described. , There is a ‘‘note on the Hudson River group,” and its use as a geological term, which recommends that the term be dropped, because of the discovery of characteristic Taconic fossils in very much of the area over which the rocks of this group had been supposed to extend in the Hudson valley, (pp. 443-445. See also foot note, p. 47.)* Of the ‘‘Buff limestone” the section given (p. 34) at the falls of St. Anthony is quite inapplicable, and must have been referred to that locality by mistake. On p. 37 the same section is referred to the Blue limestone. This limestone in southwestern Wisconsin is not regarded as so nearly resembling the typical Trenton limestone, either in lithology or in fossil remains, as the overlying Blue limestone. Its thickness is about 20 feet. It is an impure dolomyte, but sometimes quite argillaceous. The Blue limestone is thin-bedded, bluish-gray, sometimes almost entirely calcareous but usually with seams of argillaceous matter, and in some localities having a distinctly “slaty” structure. ‘‘In the northern part of the state, and the adjacent parts of Minne- sota, this rock is sometimes more heavily bedded and compact, with layers separated by several inches of shaly matter. Prof. Hall at the time considered the Buff limestone (7. e. the building-stone layers at Minneapolis) as the near parallel of the Birdseye and Black River limestones, remarking that the large orthoceratites, Gonioceras and Lituites mark in more eastern localities the horizon of the Black River limestone; and that these fossils in the west hold a position everywhere below the beds charged with the more characteristic fossils of the Trenton limestone (p. 86). . The author illustrates lamellibranchs and gasteropods from the Buff and trolibites and brachiopods from the Blue. The Galena is a compact, crystalline, heavy-bedded dolomyte with numerous cavities and veins in which sometimes is brown spar and sometimes sulphides of lead, zinc and iron, its greatest thickness being 250 feet. It was identified as far northeast as the Escanaba river in Michigan. Receptaculites is its principal fossil, but there are several species. In the upper beds Lingula quadrata usually abounds, also large orthoceratites. *“This recommendation, however, was subsequently withdrawn on the ground that the idea of the term Hudson River was not incorrect. lt was a mistake to extend the term over rocks that were found to be of Taconic age, but that was a mistake of identification. The true Hudson River idea pertained to the uppermost horizon of the Lower Silurian, and as such it had a basis of stratigraphic as well as paleontologie fact which could not be affected by any error in the mere con- struction of amap. The same mistake was made by Dr. Emmons in the represented extension of his Taconic, as he included in it erroneously some localities of Lower Silurian rock. But his idea was a primordial one, and on the later correction of his map, his idea stands as intact as that of the Hudson River group. See Am. Assc. Adv. Sci. 1877, Nashville Meeting, pp- 259-265. XXXIV THE PALEONTOLOGY OF MINNESOTA. The ‘‘Green and Blue shales and limestones” with a thickness of 60 to 100 feet, are next above the Galena. They are supposed to be in a general way, the equivalent of the Blue limestone of the Ohio geological reports and of the Utica slate, the Frankfort slate, the Pulaski shales and sandstone and the Lorraine shales of the New York geological reports. So far as noticed this is the first reference of the ‘‘Blue shales and limestone” of Ohio to this horizon in the Northwest, although they had been stated to be of the age of the Hudson River group in 1842 by Prof. Hall. The Blue limestone of Ohio had hitherto been regarded, even by Hall, as suggested by Dr. Locke, as equivalent with the Trenton, and the term was transferred from Ohio to the Mississippi valley for that reason.* This series in New York had a thickness of 800 to 1,000 feet, but gradually diminishes westward. Thecharacteristic organic remains are lamellibranchs, trilobites and bryozoans. The brachiopods are Strophomena, Orthis and Rhynchonella. Orthis occidentalis and Strophomena alternata occur in the upper beds in the southwestern part of the state and adjacent parts of lowa. However, the most abundant and characteristic fossils of the upper beds in the southwestern part of the state are a small Nucula and a Clidophorus, along with a small Pleurotomaria and an Orthoceras. The fauna of these beds in the lead region is different from that of the same stratain the region of Green bay. J. D. Whitney. 1862. Report upon the Lead Region, comprising chapters II, III, IV, V, and VI, of the ‘Report on the Geological Survey of Wisconsin, vol. i. 1862, ” last mentioned. The term ‘‘ Blue limestone” here is made to cover all the strata from the top of the St. Peter sandstone to the bottom of the Galena, comprising a vertical series of from 50 to 100 feet. The term ‘‘ Buff limestone” is quite subordinate, being applied to a non- important ‘‘buff-colored stratum” designated by that term by Dr. Owen in the map accompanying his report of 1840, as revised and republished in 1844. This term, and the stratum to which it was applied, came to be known as the Buff limestone in all later reports. It has a thickness of about 25 feet, and is supposed to be the equivalent of the Chazy, Birdseye and Black River limestones of New York. Its characteristic fossils are large Orthocerata, Lituites undatus, Maclurea magna, Columnaria alveolata and several species of Murchisonia and Pleurotomaria. The Blue limestone (supposed to be the New York Trenton limestone) is said to be a pure limestone, with abundant remainsof animal life. The first ten feet above the Buff lime- stone, very compact, brittle, and breaking conchoidally, are known as the ‘‘ glass rock,” but in the eastern portion of the lead district this term is applied generally to any portion of the Blue limestone. The thickness of the Blue averages perhaps 50 feet. The Galena is a crystalline dolomyte, 250 feet thick. “Toward the north this formation gradually dies out, and soon disappears after crossing the water- shed. * * * * ‘There are carbonaceous layers occasionally met with in the body of the Galena limestone which are not only so impregnated with organic matter as to take fire and burn with flame *This reference of the Ohio Blue limestone to the Hudson River was later confirmed by the report of a committee of the Cincinnati Society of Natural History, published in the Journal of the Society, pp. 193-194, January, 1879. See also the teath report of the Indiana Geological Survey, p. 23, 1879. HISTORICAL SKETCH. XXXV when heated, but which show distinct impressions of a vegetable character. * * * * That the same fossils which are characteristic of the Galena limestone in the lead region are found in the Blue, beyond the limits of our district, to the northwest, isa fact observed during the progress of the Iowa survey. Itis evident that after crossing the Mississippi, and proceeding beyond Gutenberg in that direction, the Galena and the Blue limestones become more and more merged in each other, and less distinguishable either by paleontological or lithological characters.” In plate Iv, giving a section of the rocks exposed in the lead region, the Galena and the Blue are together said to be the equivalent of the Trenton limestone of New York. Mr. Whitney retains the term Hudson River group for the next overlying formation— the Green and Blue shales and limestones of Prof. Hall. It is given a thickness, in the lead region, from 70 to 100 feet. It is shaly, but holds some beds of dolomyte. The shale is sometimes carbonaceous in sufficient degree, perhaps, to make it, in the future, of economical value, and is marked by traces of graptolites. James Hall. 1863. Note on the geological range of the genus Receptaculites in American Paleozoic strata. JAMES HALL. Sixteenth report of the New York State Cabinet, pp. 67-70, 1863. Five species have been described from the Galena limestone, viz., oweni, iowensis, fungosus and obicularis, and one from the Trenton limestone, occidentalis (neptuni?), in New York. F. B. Meek and A. H. Worthen. 1868. Geological Survey of Illinois, Vol. III, Paleontology, F.B. MEEK and A. H. WoORTHEN, Springfield, 1868. This volume embraces descriptions and figures of fossils from the Trenton, Galena and Hudson River formations, viz., from the Trenton one echinoderm, three lamelli- branchs, one cephalopod and one crustacean; from the Galena, one pteropod, one zoo- phyte, one brachiopod, five lamellibranchs, five gasteropods, one cephalopod, and two crustaceans; from the Hudson River, six echinoderms, three brachiopods, one gasteropod and three pteropods. CO mPAValnte: 1870. Report of the Geological Survey of Iowa. CHARLES A. WuITE. Vol. I, Des Moines, 1870. On pages 174-182 the Trenton group, of the Lower Silurian, is treated. The Trenton limestone proper is made to include the strata between the St. Peter sand- stone and the Galena limestone. Along the bluffs of the Mississippi its thickness is about eighty feet, but in Winnishiek county it increases to above two hundred feet. The Galena diminishes in thickness from Dubuque northwesterly, from 250 feet to - probably 100 feet on the northern state boundary, where it also has a greater westerly dip. The name Maquoketa shales is given to the shales lying above the Galena limestone and separating it from the Niagara limestone. They are said to be characterized by peculiar faunal features, (‘‘Orthoceras, Murchisonia, Pleurotomaria, Schizodus(?), Dis- cina, Graptolithus, etc.,”) sufficient to warrant their assignment to a very low horizon in the Cincinnati group. XXXV1 THE PALEONTOLOGY OF MINNESOTA. J. H. Kloos. 1871. Geologische Notizen aus Minnesota. By J. H. Kuoos. Zeitschr. d. Deutschen geologischen Gesellschaft, Jahrg. 1871. (Translation in the Tenth Annual Report of the Minnesota Survey, 1881). Geognostische und geographische Beobachtungen in Staate Minnesota. J. H Koos. Zeitschr. d. Gesell. f. Erdkunde zu Berlin, Bd. x11, 1877. (Translation in the Nineteenth Annual Report of the Minnesota Survey, 1890). The foregoing are titles of papers based on observations and collections made by Mr. Kloos during a sojourn in Minnesota before the commencement of the present survey. Of the Lower Silurian strata at St. Paul he mentions, in the former, the following species: Orthis tricenaria Con. and O. testudinaria Dalm., Leptcena sericea Sow., Murchisonia bicincta, Bellerophon bilobatus Sw.; ‘all characteristic shells of the Trenton, and partly also of the Llandeilo flags of England.” In higher layers he mentions the following: Rhynchonella recurvirostra H., and R. increbescens H., Petraia corniculum H., Stenopora fibrosa Goldf., Calymene senaria (blumenbachii), and Ptilodictya sp. ‘‘fossils which altogether have been assigned to the Trenton by Logan in Canada.” In the latter paper, besides the above, he mentions the following, at the same place: Strophomena alternata Con., (the ‘‘ Producti” of W. H. Keating and others), Ctenodonta nasuta Hall, Leperditia fabulites, Plewrotomaria lenticularis Con., Subulites elongata Con., Orthoceras junceum Hall, Buthotrephis succulens Owen, Palewophycus rugosus, Strophomena deltoidea Con.,,and Schizocrinus nodosus Hall. He objects to Hall’s statement that at this place the different members of the Trenton, as displayed in the eastern part of the United States, can be distinguished: ‘So far as Minnesota is concerned this must be wholly erroneous,” * * * ‘The fossils taken together point to the level of the proper Trenton limestone, and some extend much higher, in the Hudson River group, though they are not found in the lower beds in the eastern states.” W. D. Hurlbut. 1871. Geology of Southern Minnesota, by W. D. HurLBuT, in The Minnesota Teacher, Jan., Feb., March, April, May, 1871. (Vol. IV). Mr. Hurlbut was the first to direct public attention to the geology of the southern por- tion of the state, remote from the Mississippi valley. He based his observations upon a careful study of the stratigraphy of Owen. He stated that the Lower Silurian rocks form the surface over an area of about 6,000 square miles in the southern part of the state. He worked out their stratigraphy, specially along Root river and its branches, giving dia- grams illustrating their position and thickness, but without the aid of fossils. The green shales overlying the Trenton (7. e. Buff limestone) he called Hudson River oil shales, and the alternating beds of shale and limestone (7. e. the transition from the Trenton to the Galena) still higher he regarded as Clinton. The Galena limestone he considered of Devonian age, probably Corniferous, although he here mentions Maclurea and ‘other HISTORICAL SKETCH. XXXVll Silurian gasteropods,” Receptaculites, Orthis, Lingula ‘‘and probably Discina,” cyatho- phylloid corals, Tentaculites, Spirifers, trilobites, and Orthoceras.* James Shaw. 1872. Geological Survey of Illinois, vol. v, Geology, by A. H. WoRTHEN and JAMES SHaw. Springfield, 1873. The preliminary chapter in this volume, on the ‘‘Geology of Northwestern Illinois,” and several others describing several counties more specially, in that portion of the state, are by Mr. Shaw. These counties are contiguous to that part of Iowa and of Wisconsin which embrace the lead region of the Northwest, and have a bearing on the nature and extent of the Lower Silurian strata considered in this volume of the Minnesota survey. The Hudson River shales, above Savanna, are said to have an exposed thickness of 80 feet, and to reach a total thickness of about 100 feet. In the Galena the characteristic fossil is termed Receptaculites suleata, the ‘‘sunflower coral.” Below the Galena ‘‘comes the Blue limestone, or Trenton limestone proper, of the earlier western geologists. It is now regarded as the middle division of the Trenton group, the Galena above and the Buff below both being regarded as members of the Tren- ” The Blue limestone has a thickness from 45 to 60 feet, and the Buff generally about 20 feet. ton. A. H. Worthen and F. B. Meek. 1875. Geological Survey of Illinois. Vol. vi. Paleontology, Section tt. Descriptions of Invertebrates, Springfield, 1875. A few species of Lower Silurian fossils are described in this volume. They are from Dixon, Mount Carroll, Savannah and Oswego, Illinois. R. P. Whitfield 1877. Preliminary descriptions of new species of fossils from the lower geological forma- tions of Wisconsin, by R. P. WuHiITFIELD. Ann. Rpt. Wisconsin Geol. Survey for 1877; Madison, 1878; pp. 50-89. In this paper sixty-five new species are described. Those from the Trenton period, — twenty-four in number—are as follows:— Trematopora annulifer, Hudson River shales. Trematopora granulata, Hudson River shales. Fenestella granulosa, Hudson River shales. Fistulipora solidissima, Hudson River shales. Fistulipora lens, Hudson River shales. Chetetes fusiformis, Hudson River shales. Monticulipora rectangularis, Hudson River shales. Multiculipora punctata, Hudson River shales. Monticulipora multituberculata, Hudson River shales. Alveolites irregularis, Hudson River shales. Hemipronites americana, Galena. Strophomena kingi, Hudson River shales. Rhynchonella perlamellosa Hudson River shales. Cypricardites megambonus, Buil limestone. Metoptoma perovalis, Lower Blue limestone. Trochonema beloitensis, Buff limestone. Clisospira occidentalis, Buff limestone. Maclurea cuneata, Galena. Maclurea subrotunda, Galena. Bucania (Tremanolus ?) buelli, Upper Buff limesone. Hyolithes baconi, hard bluish-buff layers. Orthoceras (Actinoceras) beloitense, Buff beds. Bellerophon wisconsinensis, blue beds of Trenton limestone. Gyroceras duplicostatum, Trenton limestone and bluish-buff beds. These descriptions are republished in vol. tv of the final report of the Wisconsin sur- vey, 1882 with illustrations. Mr. Hurlbut, still resides at Rochester, Minn. The writer retains a vivid recollection of his cordial and generous wel- come by Mr. Hurlbnt when, in 1872, the present survey was inaugurated. XXXVill THE PALEONTOLOGY OF MINNESOTA. R. P. Whitfield. 1878. Geology of Wisconsin. Survey of 1878-1877. Vol. u, of the final report; Madison, 1878. T. C. CHAMBERLIN, chief geologist. In this volume are numerous references to the preliminary identification of fossils by Prof. R. P. Whitfield, paleontologist of the survey. Of these the following refer to the Lower Silurian as defined by the Minnesota Survey. Page 561 gives a list of Trenton fossils, without specification of their geographical localities; and after the discussion of the Cincinnati shales and limestones is given a full tabulation of the fossils of the Trenton period (p. 320), for which the identification of the species was by Whitfield. It appears, however, in Prof. Chamberlin’s general chapter on the ‘‘Lower Silurian” and will be mentioned more fully under his name. T. C. Chamberlin. 1878. Geology of Wisconsin. Survey of 18738-1877. Vol. u, T. C. CHAMBERLIN, chief geologist, Madison, 1878. Part 1 of this volume, entitled ‘‘Geology of Eastern Wisconsin,” is by Prof. Chamber- lin. Of this, chapter vil is devoted to the Lower Silurian, which by the author is con- sidered to include all the rocks of this district from the Archean formations to the Clinton in the Upper Silurian. The Trenton group is said to consist of three main divisions, viz., in ascending order, Trenton limestone, Galena limestone and the Cincinnati shales and limestone. The Trenton proper is given a thickness in southeastern Wisconsin of 120 feet, divided as follows: Upper Blue beds, 15 feet. Upper Buff beds, 55 feet. Lower Blue beds, 25 feet. Lower Buff beds, 25 feet. It was found that the designations ‘‘ Buff” and ‘‘Blue” of former reports had been used indiscriminately for either the upper or lower, and that the strata are all strongly dolomitic. It was learned that they cannot be separated on paleontological grounds. That which is above named Lower Buff is what: has been known generally simply as Buff. The color which has given it its name is wholly a superficial character due to weathering, the interior of the rock being blue. The Buff beds, upper and lower, are less intermixed with argillaceous matter than the Blue beds, and for that reason are more readily changed in color. The Buff beds are particularly marked by the preponderance of lamellibranchs, gasteropods and cephalopods, and the Blue beds by corals, bryozoans and small brachi- opods, especially the Orthidee. Murchisonia gracilis occurs abundantly near the base of the Lower Blue, which also contains sometimes a notable amount of carbonaceous material. “Tt appears from all the facts that there was an alternation of conditions in the depositing Trenton seas, and that when the conditions were such as to favor the formation of limestones simply, the life above characterized predominated, and that whenever the conditions changed so as to cause a deposit of shale interleaved with layers of limestone, the brachiopodous and coralline fauna prevailed. These sub- divisions than signify rather physicial mutations of a more or less local nature than wide-spread changes in the life-character of the period.” (P. 294.) HISTORICAL SKETCH. XXX1X The Galena, with a thickness of about 160 feet, reposes on the Upper Blue beds, in southeastern Wisconsin. This is another dolomyte, but sometimes has siliceous and aluminous matter in considerable amount, some of its thin layers, or partings consisting of Shale. It is in general heavy-bedded, irregular, coarse-textured, gray or butt, with fre- quent crystal-lined cavities, but toward the north becomes more shaly, and has a greenish or bluish color, with more fossils and sometimes a strongly graptolitic fauna. The Cincinnati shales and limestones, next in ascending order, have an approximate average thickness of 200 feet. The clay shales and limestones prevail in the upper por- tion, and slaty and arenaceous shales in the lower. Yet in the northern part of the area limestone prevails in the upper part over the shales. The characteristic faunal feature is the prevalence of corals and bryozoans. Upwards of 30 species were collected from the shale thrown out of two shafts of no considerable depth. Brachiopods are next in abundance, Orthis and Strophomena predominating. In recapitulation of the facts of the Trenton period Prof. Chamberlain draws three conclusions respecting its paleontology, viz: (1) There are a considerable number of species that range throughout the whole Trenton period, including the Cincinnati epoch, and are therefore of no service in discriminating between its subdivisions; (2) There is another portion whose occurrence is chiefly confined to the strata of the Trenton epoch; and, (3) There are a few that are not authentically known to occur either above, or below the Galena, and may be regarded as characteristic of it. Of this number Receptaculites oweni and Murchisonia bellicincta or major, are the most constant and reliable. Lingula quadrata, although rare in other beds in eastern Wisconsin, does not appear to be strictly confined to the Galena. Fusispira ventricosa and F. elongata are perhaps to be added to this list. The tables given by Prof. Chamberlin showing the stratigraphic distribution of species of the Trenton period distribute the species that had been identified in the following manner: In the Lower Buff, 53; Lower Blue, 57; Upper Buff, 69; Upper Blue. 25; the Trenton epoch, 195; Galena proper, 62; Galena modified, 88, and the Cincinnati, 66. Total in the Trenton period, 295. R. D. Irving. 1878. In the same volume as the last Prof. R. D. Irving described the ‘‘Geology of Central Wisconsin.” eS . aol a 3 he Eee ae a 8 Sal 3 HS 2 Bo a lee as ie ze Be ie ee ge Bee ese Bees janis alte & Ba) 2 DA So Ae md | 3S Ss: = Sil im 4 I “ou0jsoulT *soTeyg ‘9U0SOUMI'T ‘soregg ‘soTeug ‘900)SeMl'T » *‘puoulygory “BOTT ) ‘d0qdel], OAL YOR | “1VATY §,9u01S < ‘WQeuUsOUID JO JaATY UOspnyy | | | | | HISTORICAL SKETCH, i Valley since 1823. ISSISSIPP Lower Silurian in the Upper M $e “SS8T : - ‘ ‘qye1d[00YNS ‘YH solios IddIssissiq oy} MOU ‘Sef19s PUOJSeTAT[ ULRJUNOW oy} JO WIA “E08 : mae a rel ‘3011 8ONT “HM SvITT 949 Ur 4nd [[v a1J0M UPIsousR JeddQ puv ‘suoyspues JoJog 4S ‘URIsouUse JOMOT “9E8L : ¢ (qSnequoIsIaNIee “MD SNOseJIMOGIeH 9} JO Jeg ‘auoqsemIT] ARID) GEST TAN LESCCMION 28) : oa, ‘oopRreg ‘auojseutt, on sO EE ‘U9MQ puR 9x00'T _|_‘(aevisousey reddq) suojsemmty Yio eyg JO qed (rele mer mye OR ELE 4 H One parojoo yng ‘SPSL ‘RIRSBIN PUB ‘sIeqIop[ey IaMOT TRH somesp ‘(uvIsousey Jedd) euojsetmly YO 949 Jo Weg “SPST ts ‘peru09 ‘¥ “L uojuely, 249 Jo Jeqmem reddQ “EFST : “woqued, | ‘uojualy, ‘QOTLOOIN "N Uf =S,1010q 4S “LEST | *em0{SeUIIT ‘qsnevyuojs19gjva “M “DO URLINTIg emlog ‘SPST ‘OLYO JO 9UOJSOMMT] ONT G—¢E ‘ON GUOJSOUIIT SNOAJI[ISSOT eaeteee te ‘TaMQ A ‘a Fi | Soul! la—s ! II Tleqs 19}2q 38 “TS8T ‘uo0jJUuoL [, ‘9u0jSOUIIT “BUd[eY) ‘fouqIg AA PUB 194S0)T ang GET pedo tS AVE O08 | u0juel T= OUI] ONn[G{—suojsa{| [Jays 199g * ‘amo "a ‘d -pnyy pur eyrzys wong JU —eu0}soull] enTq{—ouo} TT [19US 1939q “9S “FS8I ‘oyeys ; : ‘sjaTueqd pep vnonyt euelty) auoysouml] ont “PS8I ‘areys || , : ‘VAlolod “9 ‘f ania uvisouseyy Joddq auoysawty ont “9GgT “BuaTey 944 Jo seq ‘ ‘Jaa GZ ' “IOALY UOSpNyy pur vo9 “BUd[eX) 9} MOlaq J9eJ OG ‘uoyueI, «=«6'4y GL ‘efespiigq | MOTeq speq 18H somes seqipnorydeoey uvlsouse yy “C81 ; : | *yoor ; ‘foudyIUM ‘A ‘Lf euo[ey 9U0JSIUII] VN[| | sse1y yng “SS8I 6 ‘sroS0y ‘Cd ‘H ayes BOrdL) “8981 | ‘ayeys ‘sjelueq pieapiy B[NOnNT “TO8T : 0 q1eH souer vue[ey mu0jueL J, “LOST - ; ‘yIvIQ pur UOSIEpUy Bee) suo}SOTMI] ONT pur [[eqS “GOST ‘OrgO Jo suojsomMl] en ; ; = IOATY YOR eH sourer yea Uospny | Bualey YIOK MON JO UOJUPIT—euojsomly] on[_ -ofOSDIIA : *yIOX MON JO UOJUOIT, I. *AZBUO aU “19ATY UOSpNA | “Bua[ey fae ‘akaspligD 1 ‘Koay “de ‘QuOYSeUII], ONT| OAIY YOVIG hi THE PALEONTOLOGY OF MINNESOTA. much of the underlying shale should be thus included. When, however, it was found that the Galena limestone proper had no uniform base line, but that its basal portion became shale toward the north and that other shale beds began to be interbedded in the limestone at higher levels, it was apparent that in Minnesota there was nothing left of a lithological base line, and that the only criterion on which to establish the bottom of the Galena was a downward extension of its characteristic fossils, and an enumeration of the other associated and characteristicspecies. Thus it became apparent that in Minnesota about thirty feet on- ly of the underlying shalesmight be put into the Galenaformation. In Iowa there is reason to believe that a greater thickness of the underlying strata may thus be transferred to the Galena. Owing, however, to the gradual lithologic transition from shales to limestone, or vice versa—whether horizontally or perpendicularly—it is apparent, as already remarked that the characteristic fossils of the Galena and their associates will not be found to be distributed throughout the region in complete conformity with the limits here established and the query very naturally arises whether the distinction between the Galena and the Trenton is one which on any terms, whether lithological or paleontological, ought to be perpetuated. Our results certainly show so intimate a relation between them that they might with propriety be put into the same formation with a common designation. It is barely necessary to call attention to other conclusions that spring from an in- spection of this table and a comparison of it with the tabulation of fossil species given in the introduction to part 11 of this volume. The suggestion of D. D. Owen in 1852 that the Galena can be parallelized with the Utica slate and Hudson River formations finds no support in our results, but those forma- tions are necessarily at a higher horizon if they both occur in the Northwest. The suggestion of H. D. Rogers, in 1858, that the Galena limestone is possibly the western representative of the Utica slate, more elaborated and adopted by C. D. Walcott in 1879, is not supported by our results. The terms Buff and Blue, used to designate some portions of these formations (Tren- ton), under the erroneous idea that the strata to which they were applied were of the age of the Blue limestone of Ohio (Cincinnati group), have been the source of many mistakes; and as the strata are older than their supposed equivalents, these terms ought not to be further employed. There are good reasons for believing that the Hudson River was separated from the Galena, or top of the Trenton, in the Northwest, by some physical convulsion which ex- terminated, or expelled, most of the species that preceded it. This is indicated not only by the rarity of the species that survived the change but by certain physical features that accompany the basal beds of the Hudson River. At Maquoketa, lowa, Mr. James mentions some evidence of stratigraphic non-conformity at this horizon. From this horizon upward into the limestones of the Upper Silurian the transition is not more marked than from the Galena to the Hudson River. HISTORICAL SKETCH. lui In the introduction to part 2 the reader will find further discussion of the stratigraphic peculiarities and the distribution of the fossils of the Lower Silurian. and some compari- tive tables indicating the relations of the Mississippi valley with the same rocks in New York and Canada and in the Cincinnati region. Dates of publication of the chapters of this part of this volume. The five chapters which are included in part 1 were published, in editions of one hun- dred copies each, and distributed on the dates given below. Chapter I. Cretaceous Fossil Plants from Minnesota. Feb. 15, 1893. Chapter II. The Microscopic Fauna of the Cretaceous in Minnesota, with additions from Nebraska and Illinois. Feb. 15, 1893. Chapter III. Sponges, Graptolites and Corals from the Lower Silurian of Minnesota. June 6, 1893. Chapter IV. On Lower Silurian Bryozoa of Minnesota. Jan. 15, 1893. Chapter V. The Lower Silurian Brachiopoda of Minnesota. June 6, 1893. ACKNOWLEDGMENTS. The authors of part 1 of Volume 1 are under obligations to numerous geologists for advice and codperation. Throughout the whole course of its preparation they have enjoyed the friendly aid and guidance of Mr. W. H. Scofield, late of Cannon Falls, whose familiar- ity with those formations in Goodhue and Olmsted counties has not only brought to light many fossil forms but has enabled the authors to study in the field their stratigraphy with greater fullness. Prof. James Hall generously allowed the use of advance proofs of his recent revision of the Brachiopoda (Paleontology of New York, vol. viii, part 1.) A year or more before the publication of that volume. For various favors the authors also have to thank Mr. C. D. Walcott, C. E. Beecher, Prof, J. M. Clarke, Prof. A. Hyatt, J. F. Whiteaves of the Canadian Geological Survey, Capt. A. W. Vogdes, Prof. C. W. Hall and Mr. F. W. Sardeson. Throughout the volume will be found various acknowledgments for fossils and other aid furnished. liv THE PALEONTOLOGY OF MINNESOTA. ERRATA. FOR PART I, PAGES 1 TO 474. P. 9. Add note on ‘2. Sequoia. winchelli Lx.” as follows: This species was found at Austin and is not known to occur near New Ulm. P.9. For ‘'7. Populus winchelli, sp. nov,” read 7. Populites winchelli, sp. nov. P.9. After ‘19. Aralia radiata Lx.” dele ‘‘+” in the first column and insertit in the third. P. 36. Tenth line from top, for ‘‘PLATE B” read PLATE D. Plate D. Fourth line from bottom of explanation, for “‘ARBULINA” read ORBULINA. . 69. Under “A NOMALOSPONGIA” insert pLate rv, Fies 13-15. .85. Sixth line from top, for ‘‘Galena shales” read Trenton shales. . 92. First line in description of figure, for ‘‘Galena” read Trenton. 106. Under ‘‘Family PrrLopicryonipas” add Escharopora HALL. 106. Under ‘‘Family RHINIDICTYONID&”’ add Trigonodictya ULRICH. 107. Under ‘‘Family BATosToMELLID2&” add Hridotrypa ULRICH. 107. Under “Family DieLOTRYPID2&” add Stromatotrypa ULRICH. 107. Under “Family CerAMOPORIDA” add Bythotrypa ULRICH. 110. Twenty-first line from bottom, for “Dichtyotrypa” read Dichotrypa. 157. Thirteenth line from bottom, add PLATE VIII, FIGS. 4 and 5. 171. Second line from top, for “Fres. 112” read PIGS. 1-11. 178, Eleventh line from top, for ‘“ANTHROPORA” read ARTHROPORA. 180. Under “Section @” insert S. exigua Ulrich, Trenton limestone, Canada. .184, “STICTOPORELLA EXIGUA” should be described here; for description see explanation to plate XIII. P. 185. Fourteenth line from bottom, for ‘‘Clathopora” read Clathropora. P. 220. Eighteenth line from top, add Reappears in the upper part of the Galena shales. P. 244. First and second lines from bottom, dele “and only * * * * * Lower Silurian,” andada An examination of the types of this species proves it to be an Aspidopora. It should be added therefore to the species of that genus on page 255. P. 255. See erratum for page 244. P. 281. Fourteenth line from top, for -PiGs. 15” read FIGS. 13-15. P. 321. Fifth line from top, for ‘‘Stromatotrypa ovalis” reaa Stromatotrypa ovata. P. 339. Eleventh line from bottom, for ‘‘pl. L,’’ read pl. 1. P. 375. Fourth line from top, for ‘‘pl. rv H,” read pl.1v I. Pp. 382 and 388. Substitute Parastrophia in all places for ‘‘Anastrophia.” P. 385. Insert S. winchelli Hall, Trenton between the eighth and ninth lines, P. 391. Fourth line from top, for “pl. x1 A” read pl. rx A. P. 407. Seventeenth line from bottom, add PLATE XXXII, FIGS. 59 and 60. P. 453. Fifteenth line from top, for «Pras. 48 and 49" read FIGS. 48-50. P. 455. Second line from top, for “PIGS. 49 and 52” read PIGS. 51-54. P. 458. Second line from top, for “FIGS. 53 and 54” read FIGS. 55 and 56. Pp. 471. Seventh line from bottom, after “HHALLINA” add a note as follows: The genus Hallina is later known to be a young condition of Zygospira, of which itis asynonym. (See Proce. Biol. Soc. Washington, 1893.) DOW rN GEOLOGICAL AND NATURAL HISTORY SURVEY OF MINNESOTA. PALEONTOLOGY. CHAPTER I. Ch PAChOuUS FOSS PLANTS FROM MINNESOTA. BY LEO LESQUEREUX. In looking over the long series of the groups of plants which have inhabited the earth at the divers periods of its evolution, none appear so remarkable, none excite so much of interest and stimulate so forcibly the mind to researches by problems of importance and magnitude, as that of the Middle Cretaceous known in North America as the flora of the Dakota group. The geological area occupied by the formation, its thickness and the constitution of the rocks are well known.* Some portions of its flora have been already described by European and American authors in more or less complete memoirs which have put in evidence the great variety and luxuriance of its constituents. It seems, therefore, that the vegetation of that period should be satisfactorily known, from the fossil remains which have been determined until now, but, nevertheless, every new research in this field brings forth some facts which contribute to more evidently expose the peculiar character of the flora and its wonderful diversity. Though the above assertion has been made already at different times, it is now suggested again, by the examination of some lots of specimens procured in Minne- sota, representing a number of species, which, described below, give occasion to some remarks upon the origin, the distribution and the peculiar characters of the vegeta- tion prevalent during the period of the Middle Cretaceous, generally known as the Cenomanian. In the present stage of its progress, vegetable paleeontology has discovered evi- dent traces of land vegetation as far down as the Middle Silurian. The most ancient remains of land plants represent species of the three orders, composing the class of the Acrogens or cryptogamous vascular plants, viz: the Eyuisetacee, the Filices (or *See for what relates to the geographical and stratigraphical distribution of the Dakota Broun: F. V. Hayden's reports of the United States Geological Survey of the Territories, “Vol. VI, Cretaceous Flora, pp. 13- 2 THE PALEONTOLOGY OF MINNESOTA. (Geological introduction of plants. ferns) and the Lycopodiacee. It is very probable that, already at this old epoch some kind of phznogamous angiosperms, first representatives of the conifers and the Cycadee had their existence; for remains of Cordaites have. been found in the Lower Devonian, especially in Canada. These Cordaites, like the ferns, the Lycopods and the Equisetacew, were plants of various size; either small, floating, bushy, or large trees. Their stems or trunks were composed of a woody cylinder, the wood being disposed in concentrical circles and perforated by pores like that of the conifers, and their fruits, of very diversified forms, had a great analogy to that of the Cycadee, of which they have been considered as the ancestors or prototypes. Hence it is prob- able that from its origin the land vegetation was characterized by the four essential elements which have composed it in the long series of ages and formations from the Silurian to the Cretaceous. In the Upper Devonian already, numerous species of ferns, some of them tree ferns, the Lycopodiacee with their generic divisions, Lepidodendron, Uloden- dron, Knorria, Halonia, Lepidophloios, Sigillaria and Stigmaria; the Calamariee as Calamites, Asterophyllites, Annularia, Sphenophyllum and the Cordaitew, as Cordaites, are present. Even trunks considered by some authors as referable to the Avaucariew, a family of the conifers, have been found there in England as in America. Except- ing this last kind, all the above genera are more abundantly represented in the Carboniferous, a number of their species passing higher, into the Permian. Here while the large Lycopodiacew and a number of species of ferns lose their predomi- nance and gradually disappear, their place is taken by conifers of a peculiar type, Valchia, Ulmannia, and later in the Trias by Volzia and Albertia, all, like the Arauca- riee, of the order of the Abzetacew. It is there also that the Cordarter give place to tree Cycadew, which gradually become predominant together with the ferns and the conifers. Inthe Keuper, the Calamariew still represented by gigantic Calamites, become somewhat modified in their conformation, the articulations of their stems becoming like those of the genus Equisetum, surrounded by sheaths instead of whorls of separated narrow leaflets. But in the Lias, the Ca/amariew and the arborescent ferns become, like the Lycopodiacew, mostly reduced to herbaceous plants ; and in the Odlyte, the Jurassic, the Wealden, even the Lower Cretaceous, the whole vege- tation, though modified in its aspect and its forms, is still composed of acrogenous and gymnospermous plants with a few monocotyledons of as yet uncertain affinity. Still in the Cretaceous, but near its base in Europe, the vegetable remains attest the persistence of that peculiar and uniform vegetation which has inhabited the land during such a long series of geological periods. For example, in the Vernsdorf schists of North Germany, which by their fauna and their geological stage Flora of the Dakota group.] De ota, de ae ei ? are referable to the Urgonian or Lower Cretaceous, a group of plants has been dis- covered composed of 1 algoid, 3 ferns, 12 Cycadee, 5 conifers and ‘1 monocotyledon. The characters of these plants are like those of the plants of the Wealden and of the Jurassic. In Greenland, the Swedish expedition under the direction of Nordens- kidld also found at Korne, in strata which by their fauna are referable to about the same geological subdivision of the Lower Cretaceous as the Vernsdorf schists, a group of 8S species of plants representing 48 ferns, 1 Marsilia, 1 Lycopod, 3 species of Equisetum, 14 Zamiew, 17 conifers, 5 monocotyledons with a few frag- ments of a leaf of a dicotyledonous species, a Populus which Heer, who has examined and determined the plants, has named Populus primeva. Here still we find precisely the same elements of vegetation as in the Wealden and the Jurassic, except that leaf of Populus. It is from this point or from above the lower Urgonian subdivision that appear the earlier American Cretaceous strata, those of the Dakota group, imme- diately superposed, in the western states to the Permian magnesian limestone. Above this formation and up to the base of the Tertiary, one passes, in ascending through the four geological subdivisions fixed by Hayden and Meek, the Benton, the Niobrara, the Fort Pierre and the Fox Hill groups. The fauna of the Benton group is that of the Cenomanian of d’Orbigny; by its position the Dakota group is referable to the same subdivision, while its flora is that of the Middle Cretaceous of Greenland and of the Quader sandstone of Germany. Its geological stage is thus positively fixed as succeeding the Urgonian, where, as seen above, the types of the vegetation are still mostly Jurassic and without any trace of dicotyledons, except that Populus found by Heer among the 88 species of Korne. Now, the flora of the Dakota group is of a totally different character. As known at the present it has in more that 200 species of plants which have been determined, 1 Hquisetum, 6 ferns, 6 Cycadew, 10 conifers, 3 monocotyledons and 175 dicotyledons, these being in the proportion of 81 per cent. while the other .groups of plants, including the monocotyledons, remain relatively the same. The flora of Atane which has been discovered in Greenland in strata at a higher stage of the Cretaceous than that of Korne, and which is also referable to the Cenomanian by its fauna, has about the same elements in its composition. In 177 species described by Heer, it has 3 Fung: (Hyporylee upon leaves of dicotyledons), 31 ferns, 1 Marsilia, 1 Selaginella, 1 Equisetum, 11 Cycadee, 24 conifers, 8 monocotyledons and 97 dicotyledons, or a proportion of 55 per cent. of dicotyledons. This group of plants has a greater number of ferns and conifers than that of the Dakota group, a difference evidently due to the influence of local atmo- spheric circumstances. In collections recently made of plants of the Dakota group, 4 THE PALEONTOLOGY OF AMUN ESO TC i See ee oe eee the number of species of Cycadew is greatly increased at some localities and most probably the conifers and the ferns may be found also more abundant at some others. The flora of Atane, and that of the Dakota group have a number of identical species. As yet, no remains of fossil plants have been described from the American Cretaceous above the Dakota group. But in Greenland, at a higher stage than that of Atane and in strata considered as referable to the Lower Senonian, Upper Creta- ceous, the same discoverers have found a group of plants still related to the Ceno- manian by some identical species, and comprising in 118 species, 1 fungus, 19 ferns, 1 Equisetum, 17 conifers, 5 monocotyledons and 75 dicotyledons. In this flora the proportion of the dicotyledons is 63 percent., and the general character of the vege- tation is evidently the same. In continuing the researches above, in the subsequent formations, we would find the same kind of gradual change and the same proportion in the composition of the flora. Some of the types are modified in the character of the species, which either disappear or are constituted as new; but the general proportion in the constituents of the floras remains about the same. For example, at the base of the Tertiary, the flora of the Laramie group, Lower Eocene in character, has in its composition a proportion of 66 per cent. of dicotyledons. It has, moreover, a new element in the predominance of the palms, of which very few remains have been found in the Cretaceous. But above, in the Oligocene where the palms have become extremely rare, the proportion of the dicotyle- dons remains the same, as it is also in the Miocene, and in the flora of the present epoch, being merely modified by local influences, especially by variations of temperature. Is it then possible to explain in some way the total change noticed in the char- acters of the vegetation of the earth in the middle of the Cretaceous? ‘To show the difficulty of the solution of a problem like that of the appearance of the dicoty- ledons in the flora of that period, it is necessary to know something more about the characters of those primitive dicotyledons, as we find them in the Dakota group. To admit, as do some authors, that the change has been produced by a gradual modification of some types, caused by external influences, one would suppose, in considering the large number of dicotyledons now known from the Middle Creta- ceous, that it would be possible to find some traces of the successive degrees of mod- ifications which, of course, can not have acted merely upon the leaves, or upon a single kind of organ, but upon all the parts of a plant. No species of the dicotyle- donous series has as yet shown any such intermediate characters indicating by its inferiority a degree of transition ; and thus, of all the species found in the strata of the Middle Cretaceous, it is not possible to consider any one as being of a lower or oe Le er CRETACEOUS FLORA, degree of organization than another. And also, in the large number of vegetable remains of the lower division of plants, none have been found in the long series of ancient vegetables, whose characters would indicate a tendency to a transition to a «a higher order. Some ferns of the Trias and the Lias, even of the Carboniferous, are by their outlines, like dicotyledonous leaves, but their nervation is always far different, and, moreover, as said above, the likeness of a leaf can not by itself indi- cate a relation in the characters of a plant, as in passing for example, from a fern to a dicotyledon the whole plant has to be modified, the structure of the stem, the wood, the flowers, fruits, ete. Evolutionists may trace the derivation of a species of mammals from one to another, but they can not look for such transitional forms between a saurian and a mammal; and it is a difference of this kind which exists between the dicotyledons and the lower series of vegetables predominant from the origin of the land plants to the Wealden. But more. If the change had proceeded by slow degrees of modification of one species, the results would be, of course, a great uniformity or an affinity of parentage noticeable in the derived types. That is certainly not the case for the flora of the Dakota group, as it is known at the present time, has its dicotyledonous species referable to the three great divisions of the present dicotyledonous flora; the Apeta- lew, the Gamopetalee and the Dialapetalee. Of the first, it has the Amentacew with species of the genera Myrica, Betula, Alnus; the Cupuliferee with Fagus, Quercus, Salix, Populus, Platanus, Liquidambar; the Moree with Ficus; the Proteacee with Proteoides, Todea, Lomatia; the Lauracee with Laurus, Persea, Sassafras, Cinnamomum, Oreodaphne; the Aristolochieew with Aristolochia. Of the second, it has the species of Diospyros in the Diospyrinee and of Andromeda in the Ericacee. Of the third, it has the Araliacee with a number of species of Aralia, and of Hedera; the Ampelidee with Cissus; the Polycarpee with Magnolia, Liriodendron, Liriophyllum, Anona anda number of species of Menispermacee ; the Malvacee with Sterculia; the Tiliacee with Greviopsis ; the Aceracee with Acerites, and especially Sapindus; the Frangulacee with Ilex, Palinurus, Rhamnus; the Terebinthinew, with Juglans and Rhus; the Rosifloree with a Pyrus and a Prunus; then species of the Leauminosee with a number of leaves assigned to genera whose affinity with plants of the present epoch is not distinctly marked. How is it possible toadmit or even suppose that plauts referable to such a number of genera distributed in divers families of the three essential subdivisions of the dicotyledons might have originated by gradual modifications of one or more species of the inferior classes of plants, to which, as remarked above, it has been impossible to find any kind of analogy, and this, too, during the time of transition between two consecutive periods, the Urgonian and the Cenomanian? 6 THE PALEONTOLOGY OF MINNESOTA. [Correlation of floras. In considering the question of the correlation of the plants recognized in the succession of the floras since their origin, one forcibly arrives at the same conclusion, the impossibility of explaining by antecedents the characters ot the vegetation of the Middle Cretaceous, or rather the presence of the dicotyledons as its essential element. From the beginning and in closely following the march of the vegetation, we find an evident degree of parentage between the groups which disappear and those which follow them. Thus the affiliation of the ferns of the Devonian to those of the Catskill group ; then to those of the Subcarboniferous, is easily followed up into the Permian, and still, by gradual modification through the ages, to the present epoch. The great Lycopodiacee,—Sigillaria, Lepidudendron, etc., gradually take a more marked place in the vegetation of the paleozoic times, have the highest degree of predomi- nance in the Carboniferous, have their time of decline in the Permian, but continue to be represented up to the present epoch by plants of the same kind but of small size. The conifers also, which distinctly appear in the Permian by peculiar forms, gradually becoming more predominant, constitute the essential vegetation of the Jurassic, still remain in the present flora under somewhat modified forms. The Cycadew, apparently as old as the Lycopodiacee, follow the same march of development traversing the Carboniferous as an essential constituent of the vegetation, declining in the Permian and by modification of some of their characters passing to the Cycadew which then follow the same march as the conifers. There is, indeed, between the Cordaitee and the Cycadew a marked difference, but the mode of gradual transform- ation between plants which have such great analogy of characters may be easily conceived. After following the gradual variations of types through the palzozoic time one may follow them still from the Cretaceous and see them also continued upon the dicotyledons from their appearance through the cenozoic ages, to the pres- ent epoch. Hence all the groups of vegetables appear from their origin as linked together by a kind of putative affihation ; but nothing like that can be seen to fore- tell the appearance of the dicotyledons in the Middle Cretaceous ; the parentage is derived from them in the hereafter, but none can be found in the past. As we see it in the Dakota group, in the formation of Atane in Greenland, and also in the Middle Cretaceous of Europe, the Cenomanian fora appears in its distri- bution and in the general character of its groups, as a complex assemblage of vege- table types developed under the acting forces of a long series of ages. Though a number of species are found identical at the different localities, the groups are generally different in characters. For example, the four species of Populus of Greenland are of the section of the coriaceous poplars, and of these, none is found in the Dakota group. Of the seven species of Quercus described from Greenland, two Cretaceous floras isolated. ] a ee ee ‘ f are identified in the Cretaceous of Germany, none in the Dakota group, which has species of oaks of a different type. Of the Lawrinee, Greenland has seven ; we have seventeen in the Dakota group; Europe has none, while species of Credneria are numerous in the Quader sandstone of Germany, and one only has been described from Greenland and one from the Dakota group. The same differences are observed in some of the other groups, while some present a remarkable degree of affinity. The same remark is applicable to the distribution of the plants upon the land surface of the formation in North America. Kansas, for example, has many species which have not been found in Nebraska or in Colorado, and vice versa. Inthe small number of species described here below from Minnesota, there are eight which have not been found elsewhere and are considered asnew. The geographical distribution, as far as it is known at the present time, is really more complex and varied than it is in the vegetation of the present epoch. The vegetable remains are not found strewn over large surfaces of the land, as if they were derived- from forests of wide extent, but over small isolated areas, more or less distant from each other, as if the leaves found there had fallen from groups of trees growing separate upon small islands or around wood swamps of small extent. And generally the plants of each area are of the same or of related species or represent only few species or genera, each locality having some plants proper to it. At one place the Sassafras abounds ; at another the Laurinew; still at another the Liriodendron, or species of another genus or family. Such a distribution does not agree with what it should be for plants derived by evolution of one or more species, as the plants of the same kind or varieties should, of course, remain together or follow the same range and direction in their distribution. It is worth remarking that as far as it can be observed neither the geological features nor the conditions of the atmosphere of the Middle Cretaceous have been subjected to great changes. The cataclysms caused by volcanic agency, and the gradual elevation of the chain of the Rocky mountains, have come after the Cretaceous. Nothing in the vegetation of that epoch indicates great and prolonged disturbances of the atmosphere. In the lower series of the vegetable scale, the ferns, the conifers and the Cycadew are of the same type and some of the same species, as in the Wealden, the Vernsdorf shale of the Lower Cretaceous, the schists of Korne, and those of the Cenomanian of Atane in Greenland. And from the time when the dicotyledonous plants appeared, or when we find them predominant, some of the types which may be called primitive, as it is not possible to refer them by derivation to some anterior ones, have continued in the different groups of floras through the Upper Cretaceous and the Tertiary to the present epoch, modified, indeed, but distinct enough to be recognized in many genera and species of the living flora of this country. 8 THE PALEONTOLOGY OF MINNESOTA. [Number of Minnesota Cretaceous plants. The small lot of specimens of Cretaceous fossil plants obtained in Minne- sota by the state geologist Prof. N. H. Winchell, and described here below may serve as a confirmation of the above remarks. The number of specimens, 55, represent no less than 28 species. Of these two only are of gymnospermous plants; all the other, dicotyledonous, are referable to eighteen genera pertaining to the three great sabdivisions of the dicotyledons, the Apetalew, the Gamopetalew, and the Dialapetalew. APETALEZ. GAMOPETALE 2, DIALAPETALEZ. Populus. Diospyros. Aralia. Salix. Andromeda. Cissus. Alnites. Credneria. Platanus. Magnolia. Ficus. Dewalquea. Laurus. Juglans. Cinnamomum. Sapindus. Crateegus. Protophyllum. The relation of the genus Protophyllum, represented by two species, though still uncertain, is most probably to Credneria, and therefore shall be admitted in the Dialapetalee. CRETACEOUS FLORA. 9 Distribution of Minnesota species. ] The following table sufficiently shows the botanical and geographical distribution of the species. 28 : wre E 2 Ss E : 7 8 < oe S 3 A 5 ies tion aes Gy\mnos pe rmee. ain REE TUSHSPECLES Me mate eileen tesla T 2. Sequoia winchelli Lx.................. t ae ealnten SEE PONUliLES CLEG ONS LUX eer siercte ests) =) t= t tT 4. Populites cyclophyllus Heer....... .... t t t 5. Populites litigiosus Heer............... Tt tT t 6. Populites laneastriensis Lx...........- it T 7. Populus winchelli, sp. n0V............-. t 8. Populus berggreni Heer.............+-- t tT 9. Salix proteifolia Lx.............. fo T t t 10. Almites crassus, SP. NOV.....-....+++ 00: t 11. Platanus primeva Lx................. i 12. Ficus austiniana sp. noy........... A ai VSS PHMCUS SPECIES + o15 afeletar=)atayoieicte sieve ietcfom aiaistoe tT 14. Laurus nebrascensis Lx..............-. ii | i t 15. Laurus plutonia Heer...............-. vy tT T 16. Cinnamomum scheuchzeri Heer......... t | t t 17. Diospyros pseudo-anceps, Sp. NOV....... yt Famopetalele. 18. Andromeda parlatovi Heer............ t if i t Ih Alia goiter pe oeen ssancodes coor tT Diallapetaliee. 20. Cissus brownianda, Sp. NOV.....+....+++5 + tT 21. Magnolia alternans Heer............-. iT 1 t tT 22. Dewalquea primordialis, sp. noy.......| 28. Juglans debeyana (H.) Lx............+ + f t 24. Crategus ativina Heer................ t A t 25.) Sapindus morrisons ix... 2.0.2...) i t 1 26. Leguminosites species............-..--- t | 27. Protophyllum crednerioides Lx......... + | t | | 28. Protophyllum integerrimum Lx....-...- + 10 THE PALEONTOLOGY OF MINNESOTA. DESCRIPTION OF SPECIES OF CRETACEOUS FOSSIL PLANTS OF MINNESOTA. 1. Pinus species. Leaf comparatively very long, narrow, linear, medial nerve broad; borders flat, irregu- larly very thinly striate lengthwise. The fragment of a leaf 11 cm. long, 24mm. broad, is as far as ean be seen that ot a simple leaf of a Pinus, much like Pinus hayesiana Heer, of the Tertiary of Green- land. The medial nerve is obsolete in some parts of the leaves, very distinct in others. Hab. North side of the Big Cottonwood river near New Ulm. Mus. Reg. No. 5160. 2. SEQUOIA WINCHELLI, sp. nov. PLATE A, FIG. 1. First An. Rep. Minn. Sur., p. 114. Final Rep., Vol. I, p. 354. Branches slender, leaves linear-oblong, obtuse, gradually narrowed to a linear decurring base, disconnected from the branches, at least in the upper part; medial nerve thin, sometimes obsolete; surface transversely rugulose under the thin epidermis. A beautiful species with slender pinnately divided branches; leaves and branchlets subdistichous and sub-opposite, half open; leaves 8 mm. long or a little less, 14 to 2 mm. broad at the middle, equally narrowed upward to an obtuse apex, and downward to a narrow linear prolongation, decurring upon the branches, but disconnected from them in the upper part or under the point of union to the leaves. The only relative known to the species is Sequoia brevifolia Heer, abundantly found near the base of the Laramie group formation at Point of Rocks, Wyoming, and also in the Miocene of the Baltic in Germany. The leaves of the Cretaceous species are narrower, their base more distinctly decurrent and detached from the stems. Hab. Austin, Minnesota. Mus. Reg. No. 115. PoPULITES ELEGANS Lesqa. PLATE A, FIG. 2; PLATE, B, FIG. 1. U. S. Geol. Report, F. V. Hayden, Vol. VI. Cret. Fl. p. 59, bl. Il, Fig. 3.* Leaves broadly oval, obtuse, or nearly reund, narrowed at base by an abrupt curve to a *The quotations of this work are merely indicated here below as Cret. Fl. CRETACEOUS FLORA. 1] Populites.] long petiole; borders entire, undulate; nervation obscurely tripalmate; and craspedodrome primary lateral nerves emerging at a distance above the basal borders, [have figured two fragments of this species, in order to show the real form of the leaves. In comparing the two figures it will be seen that in Pl. A, fig. 2, the primary lateral nerves are at a slightly greater distance above the basal border than in Pl. B, fig. 1, a fragment which has exactly the same characters as in the leaf in Cret. Fl. loc. cit. The leaves are generally large, about 9 cm. long and nearly as broad. The lateral nerves about parallel, at an angle of divergence of 40°, branch under- neath, or sometimes dichotomously, the ultimate division becoming very thin, but running into the border as sub-craspedodrome, a character rarely remarked in the living species of Populus. It is for this reason that I have preserved for the leaves having this peculiar character the name of Populites. The genus Populus was abundantly represented in the Cretaceous of North America. In his Phyllites de Nebraska, Heer has described one species. Prof. Newberry has three, also from Nebraska, in his Notes on the Extinct Floras. I have added to the number three in the Cret. Fl. from Kansas and Nebraska, and one described here below, or already 8 species. And still Heer has found four species in the specimens from the Cretaceous of Atane, Greenland, a formation which, by the number of its species identical with those of the Dakota group, is evidently of the same age. Even the first and only leaf of a dicotyledon found at Korne, a stage of the Cretaceous of Greenland lower than Atane, is that of a Populus. It is remarkable that all the species of Greenland have a camptodrome nervation. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. Nos. 5155 Cc, 5377. PopuLITES cycLopHYLLUS? Fleer. Proceed. of the Acad. of Nat. Sci. of Philadelphia, 1858, p. 266. Lesqz., Cret. Fl. p.59, Pl. IV, f. 5; Pl. XXIV, f. 4. Leaves round, entire, slightly undulate rounded or truncate to the petiole, texture rather thin; nervation pinnate; lower lateral nerves, emerging at the base of the leaves all craspedodrome, straight, simple, except the lowest pair branching underneath. The species is still uncertain, as I remarked in the first description /.c, I have referred to it leaves answering to the description of Heer, but the author does not consider my reference as right. I have not seen any original specimen nor any ftgure of it. The specimens from Minnesota are mere fragments, not sufficient for a positive determination. Hab. North side of the Big Cottonwood river, near New Ulm. Mus. Reg. No. 5155. 12 THE PALEONTOLOGY OF MINNESOTA. {Populites. PopuLires Liticiosus Heer. PLATE A, FIG. 3. Populus litigiosa Heer, Phyll. du Neb., 7, p. 13, Pl. 1, f. 2. Newb’y, Notes on Extinct Flovas, p 8. Ilustr. Pl. III, f. 6; Pl. IV, f, 1. Leaves round, very entire at base; lateral nerves opposite in the lower pairs, alternate in the upper, all distant; nervilles strong, curved, not dividing, the upper forking; marginal nerve none or thin and short. Comparing the specimens from Minnesota with the figure in the “Phyll.” /.c. the identity is easily ascertained, though the figure of Heer represents a mere fragment. The author does not mention in the description the presence of a marginal or basilar nerve which in some leaves, as in the one from Minnesota, is quite strong, while in others it is thin and sometimes even indistinct. Hab. North side of the Big Cottonwood river, near New Ulm. Mus. Reg. No. 5155. PoOPULITES LANCASTRIENSIS Lesq.v. PLATE A, FIG 4. Cret. Fl. p. 58, Pl. UI, f. 1. Leaves large, broadly cordate ovate, obtusely pointed; borders entire, slightly undulate; basilar nerves in five, the upper alternate or sub-opposite, somewhat flexuous, branching from above the middle, all sub-camptodrome; nervilles very thin, the lower undivided, the upper broken and branching. The leaf is well preserved; the apex and the petiole, however, are destroyed; it is smaller than that in Cret. Fl. /. ¢., and more like that of Newb’y, Ilustr., Pl. 3, f. 7, named Populus cordifolia, but appears to be referable to the same species, though the basilar nerves are in three. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5155 D. POPULITES WINCHELLI, sp. nov. PLATE B, FIG. 2. Leaf’ coriaceous, rhomboid-elliptical, borders regularly undulate-repand; nervation palmate-pinnatifid, obscurely craspedrome; medial nerve somewhat thick; basilar lateral nerves emerging a little above the top of the petiole, sparingly branching; secondaries thin, alternate, distant, parallel, simple. A fine leaf, 7cm. long without the petiole, which is broken 1 em. below the base of the leaf, 5 cm. broad in the middle. Its form is the same as that of P. repando- SR ot se CRETACEOUS FLORA. 13 crenata Heer, in Fl. Tert. Helv. Pl. LXII, f. 6, being only smaller and narrower. It ditfers much, however, by its coriaceous texture, the secondaries equidistant, straight, and ending into the borders; their divergence being only 25°. The nervilles, at right angles to the veins, are flexuous, generally simple and percurrent. The leaf is also comparable to P. gaudini Heer, J. c., Pl. LXIV, f. 2. Hab. North side of Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5376. PoPpuULUS BERGGRENI Heer. PLATE B, FIG. 3. Heer, Arct. Fl. LI, p. 106, Pl. X XIX, f. 1-5; VI. Part 2, p. 63, Pl. XVII, f. 8a; Pl. XVII, f. 1-4a, }b, 9a, 10a; Pl. XIX, f. 1a; Pl. XL, f. va; Pl. XLI, f. 1; Pl. XLV, f. 22. Leaves ovate, equally narrowed upward to a blunt apex and downward to the base, decurring into a long petiole destroyed in the leaf; very entire; lateral nerves thin, camptodrome. In regard to the shape, the leaf is like that of Pl. XXIX, f. 5, /.¢, having however, the secondaries less arched, especially similar, for the cuneate base and the straight nervation, to Pl. XVIII, f. 3, and for the general form and size, to f. 1, of the same plate. This last has also on one side a marginal nerve following the border upward as high as the nerve above it and parallel toit. ‘The leaf is broken quite near its base, and the petiole destroyed. 1 consider the identification of this leaf as right. It has a distant relation to P. winchelli. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5383. = ALNITES ORASSUS, sp. nov. PLATE B, FIG. 4. Leaf’ coriaceous, thick, rough of surface, round-oval, obtuse, obliquely truncate at base, shallowy toothed from below the middle upward; nervation pinnate, strongly marked ; lateral nerves thick, open, parallel, alternate, the lower ones much branched ; craspedodrome. The leaf, which has the facies of an Alnus, is 54 em. long, 6 em. broad with a petiole entire or fragmentary(?) 1 em. long. It is unequilateral, somewhat inclined to one side, with 6 pairs of secondaries at an angle of divergence of 60° curving upward in traversing the lamina, the lowest joining the nerve at a short distance above the basal borders, much branching on the under side ; the upper either dicho- tomous or branching near the borders, all entering the point of the teeth with their divisions, teeth short at right angles to the borders, separated by shallow sinuses nervilles distinct and pereurrent. 4 THE PALEONTOLOGY OF MINNESOTA. [Platunus, Ficus, Laurus. The general character of the leaf is that of A. kefersteini and A. nostratum Ung. resembling some of the numerous forms of the species as figured by Heer, FI. Tert. Helv, (Ply LXX Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5368. PLATANUS PRIMEVA? Lesqu. Cret. Fl. p. 69, Pl. VIL, f. 2. A large leaf, more than 12 cm. long, 10cm. broad in the middle. The base and the borders all around are destroyed. The nervation is that of a Platanus and the species would be identified with P. primeva Lesqx., l. c., if the lateral nerves and the nervilles were not comparatively thinner. The identification with P. heeri Lesqx., or another allied species, is rendered impossible by the destruction of the lower part and of the borders of the leaf. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5155 8. FIOUS AUSTINIANA, Sp. nov. PLATE A, FIG. 5. First Annual Report, Minn Sur., p. 114. Leaves coriaceous, oblong, truncate or cordate at base, entire and undulate; nervation pinnate, camptodrome,; lateral nerves at an open angle of divergence 60°, curving in areoles at a distance from the borders, branching above into strong nervilles anastomosing at right angles with the secondary nerves or their branches. This beautiful species is represented by two fragmentary leaves, one larger (figured), broken at its upper part, recurved at base, the border being embedded into the stone, thus appearing truncate, though probably cordate. The second specimen is part of a much smaller leaf, showing only one side of the leaf less the point, with the nervation deeply marked and perfectly distinct. The nervation is of the same character as that of Ficus protogea Ett., Kreide Fl., v. Nieders, p. 15, Pl. II, f. 5; a species also represented by a mere fragment whose nervation is the only point of affinity observable. Hab. Northside of the Cottonwood river, in North Star, Brown Co., and Austin, Mower Co., Minnesota. Mus. Reg. Nos. 3808 and 5163. Laurus pLutonia? Heer. PLATE A, FIG. 6; PLATE B, FIG 5. Leaves sub-coriaceous, lanceolate, narrowed from the middle upward to a somewhat long, blunt-pointed acumen, downward to a short petiole, very entire; primary nerve com- Sree CRETACEOUS FLORA, 15 paratively thick, straight; secondaries numerous, alternate; slender, at an acute angle of divergence, parallel, except those of the lower pair, more oblique and prolonged reticulate in the intervals. One of the leaves (PI. A, f. 6), is 6cm. long, nearly 2 cm. broad below the middle, with a petiole 6 mm. long; has the characters of the species as described by Heer, J. c., from specimens of the Middle Cretaceous of Greenland. The reticulation of the nervilles is obscure, the lateral veins being thin, and obsolete in the upper part, and thus the leaf appears at first like that of a Salix, but traces of the transverse nervilles are seen in the lower lateral veins, as marked upon the figure, quite as well as they would be observed upon the specimens from Atane, _figured by Heer. The other leaf, which I refer to the same species (PI. B f. 5), is longer and more linear, without any trace of nerves. It is remarkably similar to some of the figures of Heer, /. c., especially to f. 2 of Pl. XIX, and f. 4 of Pl. XX, and as these figures have scarcely any nerves distinctly seen, the absence of secondaries may be merely casual. However, the reference is not conclusive, as none of the figured leaves of Heer have the upper part represented. Another species also of the Creta- ceous of Greenland, Myrica longa Heer, Arct. Fl. VI, Part 2, p. 65, Pl. XVIII, £.9 b; Pl. XXIX, f. 15-17; Pl. XXIII, f. 10, has the leaves about of the same form and size without any nerves, but these leaves are rather linear than lanceolate, and broadly obtuse at the apex. The relation is therefore less clearly marked than with Laurus plutonia. Hab. North side of Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5157 C. The other is from Mankato. No. 5666 A. LAURUS NEBRASCENSIS Lesqz. PLATE A, FIG. 7. (Oi 9 Tt SW ep al a. Gn ew ln a OG) 8 Ee WP Leaves coriaceous, elliptical-oblong or narrowly lanceolate, obtusely pointed, tapering downward to a short, thick petiole; medial nerve thick, half round; lateral nerves at an acute angle of divergence, camptodrome. The leaf is somewhat longer and narrower than the one /. ¢., Pl. X, f. 1, but it is of the same size as that of Pl. XXVIII, f. 14. It is easily identified by the very thick medial nerve continuous to a short terete petiole. The species is not rare in the Dakota group, both in Nebraska and Kansas. Another species also frequently found in Kansas, and closely allied is L. proteifolia Lesqx., Cret. and Tert. Fl., Pl. IL, f. 9 16 THE PALEONTOLOGY OF MINNESOTA. (Cinnamomum, Andromeda. and 10. The leaves are broader, shorter and thicker ; the medial nerve only half as broad ; the secondaries close, numerous and distinct their whole length. Hab. North side of Minnesota river, eight miles below New Ulm. Mus. Reg. No. 3911. CINNAMOMUM SCHEUCHZERI? Heer’. Fl. Tert. Helv. II, p. 85, Pl. XCI, f. 4-22; Pl. XOI; Pl. XOMII, f. 1, 5. Lesqz. Uret., Fl., p. 83, 12, POX, ifs CB Leaves thick, coriaceous, polished on the upper surface, elliptical or oblong—lanceolate, pointed, narrowed by a curve to a short petiole, entire and slightly undulate, triple nerved. From the base or from above it, medial nerve thick, lower lateral nerves ascending along the borders higher than the base of the lower secondary veins, which they join by anastomosing branches. The description is that in Cret. Fl., made from better specimens than that which 1 refer to it from Minnesota, and which, broken on one side and partly covered on the other, is merely identified by its nervation. As in the specimen from Kansas, f. 3, /.c., the lower lateral nerves join the medial one close to the base of the leaf, while in the European specimens, the point of connection is generally higher, and therefore, as the species is Tertiary for Europe, the specific reference of all the leaves of the same character, found in the Dakota group, is somewhat uncertain. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5155 'T. ANDROMEDA PARLATORI Heer. Phill. du Nebr., p. 18, Pl. 1, f. 5. Lesqu., Cret. Fl., p. 88, Pl. XXIII, f. 6-7; Pl. XXVIII, f. 15. Leaves lanceolate, narrowed to the base, decurring to the short thick petiole, very entire, thickish; medial nerve thick, transversely striate, lateral nerves very thin, close, at an acute angle of divergence, camptodrome ; areolation reticulate. The species is not rare in North America and Greenland. The leaves are some- what coriaceous, larger toward the base. The specimens are often fragmentary; that of Minnesota represents only the lower half of a leaf with the lateral nerves mostly obsolete. Hab. North side of the Rig Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5157 A. CRETAOQEOUS FLORA. 17 Diospyros, Cissus.) DrospyRos PSEUDO-ANCEPS, Sp. nov. PL. B, FIG. 6. Leaf subcoriaceous, elliptical-oval, cuneiform to the base, border very entire, medial nerve strong; secondaries irregular in distance, few, curving in traversing the lamina; nervilles irregular in direction except as thin branches of the secondaries anastomosing in festoons along the borders. The leaf 4 cm. broad is apparently 7-8 cm. long, the upper part being destroyed. Comparing it with Diospyros anceps Heer, Fl. Tert. Helv. III, p. 12, Pl. CI, f. 17, it is scarcely possible to point out a difference marked enough to be considered as spe- cific. The base of the leafin the American specimen is merely slightly less rounded; the lateral nerves are as irregular in distance, those of the lowest pair close by each other, follow the borders in continuous series of bows formed by anastomose from the superior to a marginal inferior veinlet or to the borders; the nervilles are either at right angles to the secondaries and obsolete or passing from the medial nerve to join the secondaries at a distance, and in irregular or anormal direction. The leaf being fragmetary and the upper part destroyed, it is not possible to follow the char- acters in its upper part. Hab. North of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg, No. 5372. CIssUS BROWNIANA, sp. nov. PLATE A, FIG. 8. Leaf oval, angularly undulate, obtuse at apex, the borders slightly turned down at base, penni nerve ; primary nerve straight, half cylindrical, secondaries half open, sub- opposite, parallel, rigid, the lower pairs branching, the upper simple or branching ; all the divisions craspedodrome ; nervilles straight at right angles to the nerves. The leaf is evidently petioled, the base being inclined downward as slightly decurring ; but the pedicel is destroyed. Except the petiole, the leaf is fully preserved, 6 cm. long, 44 broad. The lateral nerves, 6 pairs, are at an angle of 40°, the marginal vein is marked on one side only. The species is comparable to Cissus atlantica, or Cissus nimrodi Ett., Bilin. FI. 111, p.3and 4, Pl. XL, f. 3-10, two species of the Tertiary, which differ from it by the leaves being smaller, more distinctly irregularly undulate-dentate, and short pointed. The nervation is of the same character. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota, Mus. Reg. No. 5156. —2 18 THE PALEONTOLOGY OF MINNESOTA. (Magnolia, Dewalquea. MAGNOLIA ALTERNANS Heer. PLATE A, FIG. 9. Heer, Phi du INebs, ps 20, Pl. Ts vf. 2-40 bl LV fa Ly) on esa. Cret, Hl. pexdenm bl.) exc VALI paws: Newby. Notes on Extinct Floras, p. 8, Illustr. Pl. V, f. 6. Leaves subcoriaceous, elliptical, very entire, rounded at base in narrowing to the petiole ; medial nerve deep and narrow ; secondary nerves at an acute angle of divergence, curved in passing to the borders, camptodrome, separated by shorter, thinner veins. The leaves are variable in size and form, generally narrower, even acutely nar- rowed at base, but also often rounded in the lower part. They are not rare in the whole extent of the Dakota group, also found in Greenland. ‘hey are easily known by their peculiar nervation, the secondary nerves being generally separated by thinner, shorter tertiary ones, which, however, are not always distinguish- able. The leaves vary in size from 8 to 10 cm. long, and from 24 to 5 em. broad in the middle. The divergence of the lateral veins from the midrib is 35°—40°. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5155 B. DEWALQUEA PRIMORDALIS, Sp. 0D. PLATE A, FIG. 10. Leaflet coriaceous, oblanceolate or gradually narrowed from below the apex to the base, very entire; borders incurved ; medial nerve thin, nearly equal iis whole length ; lateral nerves at unequal distance, very oblique, camptrodrome, the lower more or less curved, the upper nearly straight. The genus Dewalquea was established by Saporta and Marion in Marnes Hersiennes of Gelinden, p. 55, for plants which the authors refer to the Ranun- culacee—Helleboree with the following characters: “Leaves coriaceous, petiolate, pedately or palmately divided in 3, 5,7 leaflets, either dentate on the borders or entire, penni nerve, the secondary nerves more or less oblique, curving in areoles near the borders.” At first remains of species of this genus had been found only in the upper part of the Cretaceous, the Senonian. Heer has lately described two species from Patoot in Greenland, a formation somewhat more recent than that of the Dakota group, but where a number of species of this formation are still found. The specimen from Minnesota represents only a leaflet or a lobe, but its char- acters indicate its connection to a palmately divided leaf. It has a marked relation to D. gelindensis Sap. and Mar., /. c. p. 61, Pl. 1X, f. 3b. Identity with this species: could even be admitted if the lateral nerves were not at a slightly more acute angle of divergence in the American form, and also less curved in passing to the borders. CRETACEOUS FLORA, 19 Dewalquea, Sapind s] ' The leaflet is also related, though in a less degree, to D. greenlandica Heer, a species found at divers localities and stages of the Cretaceous of Greenland. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5158. JUGLANS DEBEYANA (Heer) Lesqua. PLATE B, FIG. 7. Populus debeyana Heer, Phillites du Nebraska, p. 14, Pl.1,f.1. Newby., Ext. Fl., p. 17, Illustr. Pl. 1V, f. 8. Juglans(?) debeyana Lw., Cret. Fl., p. 110, Pl. XXIII, f. 1-5. Leaves coriaceous, entire, ovate, obtuse or with a short obtuse point ; rounded subcordate at the base or narrowed by a curve and slightly decurring to the petiole ; medial nerve thick ; secondaries numerous, open, camptodrome, generally separated by short tertiaries ; areola- tion reticulate. This species is not rare in the red sandstone of Kansas and Nebraska. Prof. Heer, who had seen a single large specimen with the surface somewhat effaced, referred it with doubt to the genus Populus. The nervation is indeed too different, and, as seen from a large number of specimens, some of which are figured, Cret. FI. l.c., the leaves, rarely large, cordate at base and long petioled, are more generally small or of various sizes, 4 to 12 cm. long. 34 to 7 cm. broad, narrowed to the base and often inclined on one side like leaflets of compound leaves. For this reason I referred them to Juglans. The nervation is peculiar, the secondaries close, parallel at an angle of 50° to 60° are camptodrome abruptly curving and forming arches along, but not quite near the borders, separated by short tertiaries which, by anas- tomosing on both sides with secondaries and irregularly dividing in the middle, form a quadrangular very distinct reticulation more analogous to that of some species of Juglans, like J. latifolia Heer, Fl. Tert. Helv., ILI, p. 88, Pl. CXXIX, f. 3, 6, 9. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 53738. SAPINDUS MORRISONI Lesqw. PLATE A, FIGS. 11, 12. Cret. and Lert. Fl., Pl. XVI, f. 1, 2. Leaflets subcoriaceous, short petioled, lanceolate, acuminate, unequally narrowed in a curve to a short petiole and slightly decurring to it ; lateral nerves alternate, close, parallel, curving in passing to the borders, camptodrome. The leaves vary in width and are sometimes ovate, as in fig. 12, sometimes, also, nearly linear in the middle, as in fig. 11, but always unequal at the base. 20 THE PALEONTOLOGY OF MINNESOTA. [Cratewgus, Protophyllum. This species, first found in the Dakota group of Colorado, has been lately sent from Kansas also. It is not rare in Greenland. < Hab.: North side of Minnesota river, eight miles below New Ulm, Minnesota. Mus. Reg. Nos. 3808, 3912. Cartamaus avavina Heer. PLATE B, FIG. 8. Arct. Fl., Vol. VIL, p. 48, Pl. LXIV, f. 11. Leaves ovate, deeply cut on the borders in large obtuse teeth ; secondary nerves branch- ing craspedodrome. The borders and the teeth of the leaf are destroyed, but the size, the shape of the leaves and the nervation, seem to fully authorize the reference to Heer’s species. The leaf is coriaceous, the basal nerves opposite, attached above the basal border; the five pairs of secondaries, at the same angle of divergence of 60°, are parallel and inequidistant, and of the same character as seen in the figure of Heer, /. c. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5379. PROTOPHYLLUM CREDNERIOIDES ? Lesqz. PLATE B, FIG 9. Cret. and Tert. Fl., p. 90, Pl. I, f. 1-8. Leaves coriaceous, usually small, nearly round, broadly cuneate, rounded or subtrun- cate at base with a long slender petiole, borders entire or more generally undulate, nervation obscurely trifid ; secondary nerves equidistant, at various angles of divergence more or less branching. The leaf, which I refer with some doubt to this species, is only 4 em. long and 34 broad, with a petiole 2 cm.long. Its shape is nearly round. It differs essentially from the other leaves seen as yet of this species, in its less complex nervation, the two lower lateral nerves only being branched, and the lateral primaries being alter- nate. This difference may be due to the small size of the leaf, which has, notwith- standing, the essential characters of the genus, the shape, the craspedodrome nervation, and the long petiole. Hab. North side of the Big Cottonwood river, near New Ulm, Minnesota. Mus. Reg. No. 5380. ° CRETACEOUS FLORA. 21 Protophyllum.] PROTOPHYLLUM INTEGERRIMUM, Sp. nov. PLATE B, FIGS. 10, 11. Leaves membranaceous, of medium size, round or broadly oval in outline, rounded at base and apex, nervation palmatifid ; craspedodrome ; lower lateral nerves two pairs, very open, nearly at right angle to the broad midrib, the upper five pairs oblique and parallel, all opposite and branching underneath, except the lowest. This fine species has distinctly the characters of the genus, but is remarkable for its very entire borders, nearly smooth surface and the secondaries all opposite. This opposition of the secondaries is more or less remarked in the leaves of Proto- phyllum, as in P. quadratum and P. multinerve Lesqx., Cret. Fl, Pl. XVIII and XIX. But there is generally some deviation from the rule in the lowest nerves, while in other ‘species the opposition of all the nerves is perfect. The angle of divergence of the nerves is gradually more acute from the base upward; in these leaves, from the 3 pairs of secondaries upward, the angle of divergence is the same, 40°. Hab. Mankato, Minnesota. Mus. Reg. No. 5666, 1C. Besides the specimens described above, there are, in fragments more or less uncertainly determinable the following species worth mentioning: 6060. Mankato: nothing determinable. 6061. Salix proteifolia Lx. Part of base. A species very variable and common in the Dakota group of Kansas, Nebraska, etc. 6062. Leguminosites with nervation totally obsolete ; not determinable. 6063. Diospyros? Fragment of undeterminable leaf; no nervation distinct ; same as 6068, and perhaps as 5372 of Big Cottonwood river. 6064. Basilar part of a leaf of Avralia radiata? Lx., as far as can be seen, the lobes being destroyed. 6065. Fragment of Ficus? 6066. Same as 6062. 6067. Poor fragment; possibly same as 6068. 6068. Diospyros. Species not determinable ; nervation obsolete. 6069. ‘Three specimens with very small fragments of dicotyledonous leaves ; not determinable. SPECIMENS FROM MANKATO, 5666, 1A. Platanus primeva Lx., in fragments of leaves like those of Kansas. 5666, 1B. Fragment of a small oval, dentate? leaf, probably a Ficus; not determinable. 5666, 1C. Protophyllum integerrimum, sp. nov. Counterpart of 5666. (?) 5666, 2. Protophyllum integerrimum, sp. nov. Figured. 5666, 3. Fragments of rootlets and branches; nothing determinable. 5666, 4. Fragments of a small leaf like 5666, 1B. 5666, 5a. Laurus plutonia Heer. Figured. 5666 5b. Protophyllum integerrimum Lx. Fragments figured. 5666, 6. Rootlets and a dicotyledonous fragment; all undeterminable. 5666, 7. Protophyllum integerrimum Lx. =1C. Large leaf. 5666, 8. Protophyllum integerrimum. Only a small fragment. 5666, 9. Protophyllum integervimum, base of leaf. 5666, 10, 11. Small undeterminable fragments. 22 THE PALEONTOLOGY OF MINNESOTA. [List of Cretaceous plants known to occur in Minnesota. LIST OF THE CRETACEOUS PLANTS KNOWN TO OCCUR IN MINNESOTA. The page references refer to this volume, The numbers refer to registration in the University museum. I. Near New Ut, REDWOOD COUNTY. Pinus species? P.10. No. 5160. Pinus quenstedti Heer. No. 5384(A). Sequoia species ? No. 5382(A). Alnites crassus Lesqx. P. 13. Salix proteifolia Lesqx. Minn. Geol. Sur.; 12th Ann. Report, p. 12. Nos. 3912 and 5157(C). Populus berggreni Heer. P. 13. No. 5383. Populites elegans Lesqx. P.10. Nos. 5155(C) and 53477. Populites cyclophyllus(?) Heer P. 11. Nos. 5155(G), 5155(K) and 5155(P). Populites litigiosus Heer. P.12. Nos. 5155(A), 53875, 5381 and 5382(B). Populites lancastriensis Lesqx. P.12. Nos. 5155(D) and 5369. Populites winchelli Lesqx. P.12. Nos. 5374 and 5376. Platanus primeva(?) Lesqx, P.14. Nos. 5155(Q), 5155(S) and 5373. Ficus species ? No. 5386. Ficus austiniana Lesqx. P.14. Nos. 3808 and 5163. Ficus? halliana Lesqx. Hayden Survey, Vol. V1, Lesquereux, Cret. Flora, p. 68. Laurus species? Minn. Geol.Sur.; 12th Ann. Report, p. 12. No. 5158. Laurus plutonia(?) Heer. P. 14. Nos. 5157(C), 5389 and 5390. - Laurus nebrascensis Lesqx. P.15. No. 3911. Oinnamomum scheuchzeri(?) Heer. P.16. Nos. 5155(1) and 5155 (T). Diospyros pseudo-anceps Lesqx. P.17. No. 53872. Andromeda parlatovri Heer. P.16. Nos. 5157(A) and 5387. Bumelia marcouana (Heer) Lesqx. Hayden Survey, Vol. VI, p. 90. Cissus browniana Lesqx. P. 17. Nos. 5156, 5370 and 5371. Magnolia alternans Heer. P.18. Nos. 5155(B), 5155(H) and 5157(B). Liriodendron meeki Heer. Hayden Survey, Vol. VI, p. 93. Dewalquea primordialis Lesqx. P. 18. Nos. 5158 and 5388. Juglans debeyana (Heer) Lesqx. P. 19. Nos. 5373 and 5378. Crateegus atavina Heer. P. 20. No. 5379. Sapindus morrisoni Lesqx. P. 19. Nos. 3888 and 3912. Protophyllum crednerioides Lesqx. BP. 20. Nos. 5155(F) and 5380. Phyllites vanone Heer. Hayden Survey, Vol. VIII, p. 113. II. GooDHUE TOWNSHIP, GOODHUE COUNTY. Salix proteifolia Lesqx. No. 6061. Ficus species? No. 6065. Diospyros species? Nos. 6063 and 6068. Aralia radiata Lesqx? No. 6064. Leguminosites species ? No. 6062. III. NEAR MANKAYO., Platanus primeeva Lesqx. P. 14. No. 5666 1A. Laurus plutonia Heer. P. 14. Nos. 5666/A) and 5666(5a). Protophyllum inteyerrimum Lesqx. P. 21. Nos. 5666(C), 5666(CL), 5666(2), 5666(7), 5666(S) and 5666(9). IV. Austin, MOwER CounTvYy. Sequoia winchelli Lesqx. P.10. No. 115 or No. 5393. V. Locaniry Nor Known. Ficus laurophylla Lesqx. Hayden Survey, Vol. VIII, p. 50. Laurophyllum reticulatum Lesqx. Hayden Survey, Vol. VI, p. 76. i A Se _ es ER Ray © et he Ved, Bef PP a ceve 6 PLATE A. Fig. 1. SEQUOIA WINCHELLI, SP. NOV......... cee cece cece tee e ee tenet e eee tenes sete esse eeees 1M (a, Py 1 Oy Dopey Go y|s\av} 1 ACH. Ucis}] Bp panos ponbaoccuosNoopasiadS0dsr dnddncanansobdeosnooocacrpoed dood ocRd Fig. 3; POPULITHS LITIGIOSUS Heer. <. 6... ee ee cece ee eee eect eineiciet neice viecietereeseleeee ne Fig. 4. POPULITES LANCASTRIENSIS LX....---.-. 1 esse cece eee tee ee etter ee eee e eet e ences Fig. 5, FICUS AUSTINIANA, SP. TOV. ....... 0.0 e cece cence reece ete ete terete tenet e eee e eens cane Fig. 6. LLAURUS PLUTONIA? Heer.........-...000e cee cece eee cee eee ttt teen eee sete eee Big. 7. “WUAUWRUS NIBRASCENSIS TUX. 00560000 occ e oinie we a nieielnisinlels elel- le olan tilt wicisisi=/0)n\s « cieiejelsivie aicis/eisine viel= = Hig. 8: CISSUS BROWNIANA, SP. MOVs. - 62.25 ce cece ce cee wesc eset eee n cee ncetsie seers ce cese en ne Fig.’ 9. MAGNOLIA ALTERNANS Heer....... 20.52.22 cee cee ce eee cet eet te teen cee e cette teneees Fig. 10. DEWALQUIA PRIMORDIALIS, SP. MOV... 02 cee s ees cee eee eee eee eee tect ete e eect e ne ee aes Fig. 11,12. SAPINDUS MORRISONI Lx UG WE, Ee, SP YC EE UE BT a UE EEN VOL.M Plate A. INik ale Fig. 2 Fig. 3. Fig. 4 Fig. 5 Fig. 6 Nee S| Fig. 8 Fig. 9 Fig. 10 PLATE B. POPULITES ELEGANS, Lik.) 5h .0.7ccicls oo te Sere EE ociee ols aiete wlaieioteereistanto ors ocrsiciad stera eaowe POPULITES WINCHELLI, SP. NOV.........-....-- oo dsognaousubanbot Exe fopieistcl Scolenea es a ate aestaterers tore POPULUS BERGGRENI, Heer........ ALNITES CRASSUS, Sp. NOV.......... LAURUS PLUTONIA? Heer........... DIOSPYROS PSEUDO-ANCEPS, JObINOWoocoodaan6 55 OGeboOdonES doo IOG0K0ND Joo sGadeGDADdods ssleisle JUGLANS DEBEYANA (Heer) Lx..... CVAUIUAT GUS PAUINASVALINTA GEL COT3 1a sete aratencrter tree RIO IIe is ace oracle OS aise Sedan tOn dn wees PROTOPHYLLUM CREDNERIOIDES Lx PROTOPHYLLUM INTEGERRIMUM, sp. SEU Boat Ye, ESR, SP IG VE Ei BS UP aN, VOL AT Plate B MAcaRAIR Lith. Co. 0 CHAP DH RL Eth MIGROS? OBIE AL, WA UNA OF THE CRETACEOUS IN MINNESOTA, WITH ADDITIONS FROM NEBRASKA AND ILLINOIS (FORAMINIFERA, RADIOLARIA, COCCOLITHS, RHABDOLITHS). BY ANTHONY WOODWARD AND BENJAMIN W. THOMAS. I. METHODS OF MICROSCOPIC PREPARATION. The microscope of a few years ago, if compared with that now in use, was of bat little practical value, and was regarded more as an amusing toy than as an instrument of absolute necessity in scientific investigation. The geologist and the botanist were apparently satisfied with their pocket lenses, and the physician had but little use for even these. Careful students, however, were getting occasional glimpses of fields just beyond their power of satisfactory resolution. These a some- what more powerful combination of lenses would, to some extent, resolve, but would at the same time show that there were much larger and more interesting ones yet beyond their reach. Scientists and physicians at once called for objectives of higher powers, and for improved appliances, and manufacturing opticians of Europe and America have promptly and satisfactorily responded to the demand. Excellent instruments can now be secured at prices within the reach of every student. Geologists have long been familiar with fossil remains of pre-historic life, so abundant in most of the geological formations, but it is of comparatively recent date that improved microscopes have shown them that of these vast deposits there is hardly a cubie inch that does not contain the wreckage of an earlier world that teemed with animal and vegetable life, and from which can now be studied its history, climate, etc. These revelations are not infrequently of great commercial (23) 24 THE PALEONTOLOGY OF MINNESOTA. [Discovery of microscopic bodies. value as well as of scientific interest. One of which, while not quite germane to the subject under consideration, we will mention as an illustration. When the “lake tunnel”, which supplies the city of Chicago with water from lake Michigan, was in process of construction, in 1865-1867, large numbers of minute and nearly trans- lucent amber-colored discs, 4, to ;4, of an inch in diameter were discovered by two members of the Chicago Academy of Sciences, in the clay through which it was being driven, at a depth of about 86 feet below the surface. These discs were unknown to paleontologists, to several of whom they were submitted. Careful and repeated examinations showed that the whole mass of the boulder clay underlying the vicinity of Chicago was loaded with these discs, and also that the many frag- ments of shale and shale boulders in the clay were largely composed of them. This last discovery rendered it more than probable that the discs in the clay were derived from the shale, large formations of which must at some period of the world’s history have been broken up and scattered through it.(‘) The shale when lighted by a lamp or candle burned freely with a smoky flame and strong petroleum odor. Our next light was from a paper by Sir William Dawson, published in the American Journal of Science in 1871, in which he stated that similar “microscopic orbicular bodies” had been referred to by Sir W. E. Logan, in a report in 1863, as occurring in the “Upper Erian shale” at Kettle point, lake Huron, and to which he (Sir William) gave the name Sporangites huronensis(*), the two principal species of which are now known as Protosalvinia huronensis Dawson, and P. chicagoensis Thomas. Prof. Edward Orton, state geologist of Ohio, in a report on “Petroleum and Natural Gas”(’), after referring to the great fishes, &c., as described by Newberry, and other fossils of the oil and gas producing shales of Ohio, says: “But the forms already named are of small account so far as quantity is concerned when compared with certain microscopic fossils, that are of little doubt of vegetable origin, and which are accu- mulated in large amount throughout the black beds of the entire shale formation, and apparently give origin to an important extent to the bituminous character of the beds. * * * They were first discovered by B. W. Thomas, a Chicago microscopist, in the water supply clay and shale at Chicago’’(*) * * * “The thickness of the series of shale now under consideration is, in Crawford county, about 450 feet, in Loraine county about 950 feet, at Cleveland 1,350; while in Tuscarawas county the drill reached 1,860 feet, and in the Ohio valley at Wellsville, 2,600 feet in shale without reaching bottom.” On pages 413 and 414 of the same work, under heading of “Ohio Shale as a Source of Oil and Gas”, Prof. Orton says that “they contain much more oil (1) Bulletin, Chicago Academy of Sciences, No. 4, (2) Bulletin, Chicago Academy of Sciences, No. 9. (3) Geological Survey of Ohio, Vol. 6, 1888. (4) As stated above, they were first discovered by Sir W. BE. Logan, but he gave them no further notice. CRETACEOUS FLORA 25 Preparation of clay.] than any other strata with which they are associated, the great sandstone reservoirs not excepted ; and careful estimates based on chemical investigations show that if the shale series is counted at the low average of 1,000 feet in thickness for its entire area (it is over 400 miles long and 10 to 30 miles wide), it would yield over ten million [10,000,000] barrels of oil to the square mile.” While this oil must largely be separated from the shale by distillation, which is now being done at the rate of some 20 gallons to the ton, these estimates are truly bewildering. Most of the material used in these investigations was sent to us by Prof. N. H. Winchell, state geologist of Minnesota, and was of almost every kind and variety that a geologist would naturally collect for microscopical study, and they required almost as many different methods of treatment to free from them their microscopical organisms in proper condition for examination under the lens, as there were samples of material. While we cannot, of.course, give all of the various experiments necessary to ascertain the chemical character of the materia] and of its organic con- tents, before deciding whether its reduction, so as to preserve its fossils in their best condition for examination, would require the use of rain water, nitric or other acids, soda, caustic potash, &c., we will give a few general directions that may be of some assistance to beginners. One of the first essentials is that all glassware, pipettes, &c., designed for this use be absolutely clean, and that only river or rain water, recently filtered, be used ; otherwise you will probably find on your slides many beautiful organisms that do not belong to the substance under examination. Clay. In preparing most of the samples of clay, we would put about one ounce of the material, and the same amount of common washing soda, into a druggist’s two-quart clear-glass packing-bottle, not over +4 filled with water, and let it remain 12 to 24 hours, frequently shaking the bottle so as to thoroughly break up the clay. Now fill the bottle with water, and after 25 minutes carefully pour off the upper } of it. Again fill with water, and in 25 minutes decant as before ; repeating this at 25 minute intervals until the upper ? of the water in the bottle, after a 25 minute rest, will be nearly clear. A large amount of the fine sand, clay and the soda, has by this process been washed away, and the action of the soda has broken up the clay and removed most of the adhering material from the fossils. Now mount a few micro- scope slides from the residuary sand, etc., at the bottom of the bottle, by taking up with a pipette (a piece of small glass tubing makes the best pipette) a small amount of the material ; scatter very thinly over the middle of the slides; dry them thor- oughly over an alcohol lamp, or in some better way, and, while hot, cover the dry material with a few drops of Canada balsam, keeping the slide quite warm until the 26 THE PALEONTOLOGY OF MINNESOTA. {Preparation of shale and chalk. balsam will be hard when cold. As these “trial slides” are seldom of any value, it is not necessary to use cover glasses if the balsam is hardened, as above directed. A careful examination of these slides under the microscope with a good 4or 4 inch objective will decide as to the value of the material under observation, and if it proves to be only sand, pour it all out, wash the bottle, and again try the same process with another sample of clay. But if the slides show a few good fossils, the next step is to separate them as much as possible from the mass of sand, ete., with which they are associated. In this as in the first washing, specific gravity will do most of the work. Pour off most of the water and put the shells, sand, ete., into a 4 oz. beaker (or glass tumbler), wash out the bottle, fill the beaker about $ full of water, and after it has rested ten minutes, pour ? off the top through a glass funnel into the bottle, repeating this 5 or 6:times. As in the first washing, mount and examine a few slides from the material at the bottom of the bottle, mounting and preserving slides, if found to be of value. If nothing of value is found, pour out the contents of the bottle, and fill up again as before from the beaker, after five minutes rest repeating these washings and examinations at shorter resting intervals of say three, two, and one minute, or less, until nothing but the coarsest sand remains in the beaker. In that there may be a few good specimens of Polycystina. Hach layer of the clay, as deposited by its specific gravity, has now been examined, and most of the fossils are contained in some one or possibly two of them. Nineteen-twentieths of the original sample of clay have been washed away, and in the selected one-twen- tieth that remains there may be one fair fossil to one hundred grains of sand. Shale. The fossil contents of most of the softer shales can be secured by breaking up the specimen with a pair of strong pliers, crushing the shale while under water and edgewise of its lamine. This will free many of the fossils without breaking them ; then boil the firmer parts of it for a few minutes (or longer if the material requires) in a rather strong solution of washing soda, and wash and separate the fossils from the fine shale, sand, ete., by repeated decantations, as directed in the treatment of clay. Chalk. Foraminifera, coccoliths, rhabdoliths, with an occasional radiolarian (Polycystina), of which the “farmer’s chalk”, or soft limestone, is largely composed, can be freed from the rock by washing off the surface of a clean piece of it with a rather stiff brush while under the surface of the water in a bowl or basin. The water will soon become as white as milk. The specific gravity of the Foraminifera and Radiolaria will promptly carry them to the bottom, and they can partly be sep- arated from the sand, etc., by repeated washings, decantations, etc., as directed in the treatment of clay ; but unless great care be taken in this washing, the coccoliths CRETACEOUS FLORA. 27 Source of Foraminifera. | and rhabdoliths, which largely give to the water its milky appearance, will be lost. They are very fine and very light, and some of them will remain suspended in a 4 oz. beaker of water for several hours. They can be separated from the other material by repeated washings and decantations, so as to make almost pure mountings, but the resting time between decantings must be from one-half to three-quarters of an hour. II. FORAMINIFERA. This paper is the result of the preparation and microscopical examinations of several hundreds of slides of material from the boulder clays, hard and soft Creta- ceous shales, rotten or chalky limestone, etc., from various parts of Minnesota, many samples of which were collected, as already stated, by Prof. N. H. Winchell, state geologist of Minnesota; from boulder clay and fragments of shale, kindly sent by Prof. G. D. Swezey, Doan College, Nebraska, and from our own collections in Illinois and Wisconsin. Much of the material examined abounded in fossil remains of Foraminifera, radiolarians, coccoliths, rhabdoliths, fresh-water Diatomacee, sponge spicules, and other microscopical organisms ; but by far the most numerous and interesting were the calcareous casts or shells of Foraminifera, a minute mariné animal of the sub-kingdom Protozoa, class Rhizopoda. These fossils in the clays are evidently derived from the Cretaceous formations which have been broken up and their contents scattered through the boulder clays presumably in the direction of the glacial currents. In many localities in Minnesota and Nebraska, and on the upper Missouri and Niobrara rivers, the Cretaceous form- ations are yet in place, and some of the chalk rocks are almost wholly composed of these organisms. The “Kolian sand” of the Smoky Hillriver, near Lindsborg, Kansas where the river has cut its way through the Cretaceous rocks, is very rich in many species of well preserved Foraminifera, and it is probably the presence of vast numbers of these minute marine shells in the sand that gives to it its peculiar quality. The same genera and species of Foraminifera that constitute so considerable a part of some of these Cretaceous rocks, and that are so abundant in some of the boulder clays, are now living in vast numbers in the Atlantic, Mediterranean and other oceanic waters. They constitute an important ingredient of the “chalk cliffs” of England and the building stone of the city of Paris, France, is largely composed of them. The “Nummulites’’, or “Coin-stones” of which the pyramids of Egypt are built are principally Foraminifera. Fairly well preserved casts or shellsof Foraminifera were more or less abundant in most of the specimens from Minnesota and Nebraska, and a few good forms of 28 THE PALEONTOLOGY OF MINNESOTA. [Trochammina. Foraminifera and Radiolaria were secured from Illinois boulder clay. Much time and labor were given to the examination of material that did not add to the interest or value of our collection. Samples of inter-glacial peat, from Blue Earth county, Minnesota, were well filled with more than 100 species of fresh water Diatomacee, but did not yield Foraminifera, while the boulder clay both above and below the ayer of peat afforded good specimens of them. Of Foraminifera we have noted the following genera and number of species in the material submitted to us for examination: Tvochammina, 1 sp.; Textularia, 4 sp.; Spiroplecta, 1 sp.; Gaudryina, 1sp.; Verneuilina, 1 sp.; Bulimina, 2 sp.; Pleurosto- mella, 1 sp.; Bolivina, 1 sp.; Lagena, 3 sp.; Polymorphina, 1 sp.; Nodosaria, 1 sp.: Uvigerina, 2 sp.; Globigerina, 4 sp.; Orbulina, 1 sp.; Anomalina, 1 sp; Pulvinulina, 2 sp.; Operculina, 2 sp.; Nonionia, 1 sp. Total, 18 genera and 30 species, most of which are figured, and the original descriptions are given as nearly as possible. Sub-Kingdom PROTOZOA. Class RHIZOPODA. . FORAMINIFERA. LITUOLID AL. Sub-Family TROCHAMMIN A. TROCHAMMINA, Parker and Jones. TROCHAMMINA INFLATA Montagu, sp. PLATE D, FIG. 31. Nautilus inflatus MONTAGU, 1808. Test. Brit., Suppl., p. 81, pl. xviii, fig. 3. Rotalina inflata WILLIAMSON, 1858. Rec. For. Gt. Brit., p. 50, pl. iv, flgs. 93, 94. Rotalina (Trochammina) inflata PARKER and JON#s, 1859 .Ann. and Mag. Nat. Hist. ser. 3, vol. iv, p. 347, Figure, F. Trochammina inflata CARPENTER, 1862. Introd. Foram., p. 141, pl. xi, fig. 5. Trochammina squamata var. inflata PARKER and JONES, 1862. Introd. Foram., Appendix, p. 310. Trochammina inflala BRADY, 1865. Nat. Hist. Trans, Northd. and Durham, vol. i, p. 95. Trochammina inflata(?) TATE and BLAKE, 1876. Yorkshire Lias, p. 452 pl. xvii, fig. 18. Trochammina inflata BRADY 1884. Report on Foram., H. M. S. Challenger, Zool., vol. ix, p. 338, pl. xli, fig. 4. “Test free ; trochoid or convex, depressed, rotaliform ; consisting of about three convolutions, the outermost of which is formed of five or six very ventricose seg- ments with deeply excavated septal lines. Inferior face somewhat concave, with sunken umbilicus ; peripheral margin lobulated. Aperture small, arched ; situate on the inferior side of the final segment, close to the previous convolution, a little within the periphery. Color pale brown, the small primary segments much darker than the rest. Diameter ,, inch (0.7 mm).” Brapy, /oe. cit. Locality. Northeast Minn.(?). South Chicago, Il. CRETACEOUS FLORA. 29 (PE Xx TULARID As: Sub-Family TEXTULARIN A. TEXTULARIA. Defrance. TEXTULARIA GLoBULOsA Ehrenberg. Textularia,] PLATE ©, FIGS. 1-6. Teatularia globulosa EHRENBERG. Abhand. Akad. Berlin. (1838) 1839, pl. iv. Textulavia globulosa Id., Ibid., (1841) pp. 291, 4388. Teatularia globulosa Hircucock, 1843. Trans. Asso. Geol. and Nat., 1840-1842, p. 357, pl. xv, figs. TS 4B Te Textularia americana BAILEY, 1841. Amer. Jour Sci., vol. xli, p. 401, figs. 1, 2. Textularia globulosa MEEK, 1864. Smithsonian Inst. Check List, Cretaceous and Jurassic Fossils, p. 1. Textularia americana Id., Ibid., p. 1. Textularia missouriensis Id., Ibid., p. 1. Teatularia globulosa DAWSON, 1874. Can. Nat.» vol. vii, p. 253, fig. a. Textularia globulosa SCHARDT, 1884. Etudes Geol. Sur. le Pays—D’Enhaut. Bull. Soc. Vaud., vol. XX, p. 74. Textularia globulosa BALKWILL and WRIGHT, 1885. Trans. Roy. Irish Acad., p. 323. Textularia globulosa WooDWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 166, pl. iii, figs. 1-5. “T. globulosa, testula microscopica superficie levi, in adulta longiore quam lata, articulis globosis.” Enrenspere. (1838, Abhand. Akad. Berlin, p. 135.) T. globulosa, microcsopic test with a smooth surface, adult forms longer than wide, with spherical or globular chambers. Locality. Meeker county, Little Fork river, Minn. Saline county, Neb. South Chicago, Ills. Textularia globulosa is very abundant in the Minnesota clay and chalky lime- stone, and common in Nebraska, the specimens from that material being very fine. In the south Chicago material they are quite common and well preserved. Dr. G. M. Dawson, in his paper on the Foraminifera of the Cretaceous rocks of Manitoba, gives the following description of 7. globulosa: “A stout form with glo- bose chambers rapidly increasing in size at each addition, and sometimes even as broad as long. The primordial chamber, and those next to it, are often bent away several degrees from the axis of symmetry of the larger part of the shell. The sur- faces of the chambers are marked with extremely minute diagonal interrupted ridges or wrinkles.”} This description is far superior to that of Ehrenberg. The species has also been found in Dakota, and in the “Eolian sand” from the Smoky Hill river, near Lindsborg, Kansas. Textularia americana Ehrenberg. ‘This species forms a very large part of the mass of the chalk rocks of the upper Missouri and Niobrara rivers. It is found ina light cream colored Cretaceous marl on the upper Mississippi, called there “ prairie chalk”; has been examined by Prof. Bailey, and figured, but not described, in the Amer. Journ. Sci., xli. p. 401, 1841.* *Amer. Jour, Sci. 1841. +Canadian Naturalist, vti, 1874. 30 THE PALEONTOLOGY OF MINNESOTA. (Textularia. TEXTULARIA AGGLUTINANS d’Orbigny. PLATE C, FIGS. 7, 8. Textularia agglutinans VORBIGNY, 1839. Foram. Cuba, p. 144, pl. i, figs. 17, 18, 82-34. Textilaria agglutinans SEGUENZA, 1862. Atti dell’ Accad. Gioenia, vol xviii, ser. 2, p. 112. pl, ii, fig.4. Plecanium sturi KARRER, 1864. Sitzungsb. d. k. Ak. Wiss. Wien, vol. I, p. 704, pl. i, fig. 1. Textularia agglutinans PARKER and JONES, 1865. Phil. Trans., vol. cly, p. 369, pl. xv, fig. 21. Plecanium agglutinans Reuss, 1869. Sitzungsb. d. k. Ak. Wiss. Wien, vol. lix, p. 452, pl. i, figs. 1. 2. Textularia agghitinans Morstius, 1880. Foram. von Mauritius, p. 93, pl. ix, figs. 1-8. Teatularia agglutinans BRADY, 1884. Report Foram. H. M.S. Challenger. Zool., vol. ix, p. 363, pl. xliii, figs. 1-3, vars. figs. 4, 12. Textularia agglutinans WoopwARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Sur. Minn., p. 167, pl. iii, figs. 6. 7. “T. agglutinans. Testa elongato-conica, rugoso-agglutinate, alba, lateraliter con- vexiuscula ; postice cuneata ; loculis largis, ultimis convexis ; apertura semi-lunari.” D’Orsrevy. (Foram. Cuba, p. 144). Test elongate, conical, rugose, agglutinous (from grains of sand), white, laterally convex, posteriorly cuneate, segments large, the last convex, aperture semi-lunate. Tl. Locality. Meeker county and Little Fork river, near Rainy lake, northeastern Minn.; South Chicago, This species is not common in either locality. It has also been found in the Eocene shell sand at Jackson and Red Bluff, Mississippi. TEXTULARIA TURRIS d’Orbigny. PLATE C, FIGS. 9, 10. Textuluria turris VORBIGNY, 1840. Mem. Soc. Geol. France, vol. iv, p. 46, pl. iv, figs. 27, 28. Textularia tuvis PARKER and JONES, 1868. Ann. and Mag. Nat. Hist., ser. 3, vol. xi, p. 97. Textularia turris BRADY, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 366, pl. xliv, figs. 4, 5. i Teatularia turvis WOoDWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., pp. 167, 168, pl. iii, fig. 8. “Texrtularia turris is round in transverse section, elongate and tapering. It differs from Textularia trochus chiefly in its greater proportionate length and its rougher exterior, as well as in its frequent irregularity of contour.” Brapy, loc. cit. localities. Locality. Meeker county, Minn.; Saline county, Neb.; South Chicago, Ill. Very rare in all these TEXTULARIA CARINATA a’ Orbigny. PLATE ©, FIG. 11. Textularia carinala @’ORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 263, No. 23. Teatularia carinata Id., 1846. Foram. Foss. Vien., p. 247, pl. xiv, figs. 32-34. Textularia lacera Reuss, 1851. Zeitschr. d. deutsch. Geol. Gesell., vol. iii, p. 84, pl. vi, flgs. 52, 53. Tertularia ultenuata Id.. Ibid., p. 84, pl. vi, fig. 54. Textilaria carinata and Textiluria carinata var. attenuata Reuss, 1870. Sitzungsb. d. k. Ak. Wiss. Wien, vol. lxii, p. 489, No.1. Schlicht. 1870. Foram. Pietzpubl., pl. xxxili, figs. 1-4, 8, 9. Textilaria carinata HANTKEN, 1875. Mitth. Jahrb. d. k. ung. geol. Anst., vol. iv, p. 66, p. vii, fig. 8. Textularia carinata BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 360, pl. xiii, figs. 15, 16. “Testa cuneiformi, lingulata, convexiuscula, punctata, anticé dilatata, truncata, posticé obtuse acuminata, lateraliter carinata, acuta, lamellosa;,loculis angustatis, obliquis, arcuatis, marginatis.” ARS oe CRETACEOUS FLORA. 31 Shell cuneiform, lingulate, convex, punctate, anteriorly dilate, truncate, pos- teriorly obtuse acuminate, laterally carinate, acute, lamellose, foramina narrow, oblique, arcuate, marginate. Locality. Saline county, Nebraska. SPIROPLECTA, Ehrenberg. SPIROPLECTA A ERICANA HWhrenberg. PLATE ©, FIGS. 12, 13, 14. Spiroplecta americana BHREN., 1854. Mikrogeolgie, pl. xxxii, I, figs. 13, 14; IT, fig 25. Spiroplecta americana BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 376, pl. xlvy, fig. 24 a, b. Spiroplecta americana WoopWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Survey Minn., p. 168, pl. iii, fig. 9. “The test is usually much compressed, and widens rapidly towards the distal end; the lateral edges are thin and slightly lobulated, the chambers somewhat inflated, and the septal lines correspondingly depressed on the exterior; the walls are thin and smooth.” Brapy, loc. cit. Locality. Meeker county, Minn.; Saline county, Neb.; South Chicago, Ill. This species does not seem to be very widely distributed; only two specimens found, one in Minnesota, and the other in Nebraska. The specimens figured by Ehrenberg were from the Cretaceous beds of Missouri and Mis- sissippi.* We believe that in the fossil state it has only been found in North America, GAUDRYINA, dOrbigny. GAUDRYINA PUPOIDES d’Orbigny. PLATE C, FIGS. 15, 16. Gaudryina pupoides d’ORBIGNY, 1840. Mem. Soc. Geol. France, vol. iv, p. 44, pl. iv, figs. 22-24 Gaudryina pupoides Id., 1846. Foram. Foss. Vien., p. 197, pl. xxi, figs. 34-36. Gaudryina subglabra GEMBEL, 1868. Abh. d. k. bayer. Akad. Wiss., II, cl., vol. x, p. 602, pl. i, fig. 4. Gaudryina pupoides BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol ix, p. 378, pl. xlvi, figs. 1-4. Gaudryina pupoides WoopWARD and THomAs, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 168, pl. iii, fig. 10. “Guadryina pupoides is an easily recognized species. Its dimorphous mode of growth is generally very apparent, and its variability is limited to such features as the number of segments, the relative length and breadth of the test, and the degree of lateral compression. In recent shells the walls are thin and calcareous, smooth externally, and almost invariably of a greyish hue; fossil specimens sometimes exhibit a slightly rough exterior. In form and position the aperture resembles that of the typical Textularie, but it is often surrounded by a raised lip or border.” Brapy, loc. cit. Locality. Meeker county and Little Fork river, near Rainy lake, Minnesota, and Saline county, Nebraska. Moderately abundant in these localities. *Brady, Report on the Foruminifera, H. M.S. Challenger, p. 376. 32 THE PALEONTOLOGY OF MINNESOTA. (Verneuilina, Bulimina. VERNEUILINA, d’Orbigny. VERNEULINA PyemMma Lgger, sp. PLATE ©. FIGS. 17, 18. Bulimina pygmea EGGER, 1857. Neues Jahrb. fiir Min., p. 284, pl. nii, figs. 10, 11. Verneuilina pygmcea PARKER and JONES, 1863. Ann. and Mag. Nat. Hist., ser. 3, vol, xi, pp. 92, 98. Textilaria triseriata TERQUEM, 1882. Mem. Soc. Geol. France, ser. 3, vol. ii, Mem. ITI, p. 145, pl. xv. fig. 10. Verneuilina pygmea BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 385, pl, , xlvii, figs. 4-7. V. pygmea, “testa minima globulosa levigata, antice dilatata; anfractibus 3 ; loculis globosis. Longitudo } millim.” Eeemr. (1857. Neues Jahrb, fiir Min., p. 2S4.) Verneuilina pygmea, shell very small, globose, smooth. dilated in front, with three whorls, chambers globose. Length + mm. Locality. Quite rare in the boulder clay at South Chicago and Saline county, Nebraska. (Com- mon in the European Tertiary.) We have not noted it in Minnesota material. Sub-Family BULIMIN At. BULIMINA. Burimina aFFinis @’Orbigny. PLATE C, FIG. 19. Bulimia affinis VORBIGNY, 1839. Foram. Cuba, p. 105, pl. ii, figs. 25, 26. Bulimina ovulum Reuss, 1850. Haidinger’s Naturw. Abhandl., vol. iv, p. 38, pl. iv, fig. 9. Bulimina affinis BRADY, 1884. Report on Foram. H.M.S. Challenger, Zool., vol, ix, p.400, p. 1, fig. 14. B. affinis. “Testa, oblongo-ovata, laevigata, alba, postice subacuminata ; spira brevi, anfractibus quatuor subplanis; loculis convexiusculis per quamque spiram trinis. Apertura virgulari. Dimensiones. Longueur totale 4 mill.” D’Orsieny. (Foraminifera of Cuba, 1839, p 105, pl. II, figs. 25, 26.) B. affinis. Shell oblong-ovate, smooth, white, posteriorly subacuminate ; short spire, four subplanulate whorls with three somewhat: convex chambers in each spire. Aperture tubular. Dimensions, total length, 4 mm. Locality. Saline county, Nebraska. Buiimina PupomDES d’Orbigny. PLATE ©, FIGS. 20-24. Bulimina pupoides @ORBIGNY, 1846. Foram. Foss. Vien., p. 185, pl. xi, figs. 11, 12. Bulimina pupoides WILLIAMSON, 1858. Rec. Foram. Gt. Br., p. 62, pl. v, figs. 124, 125. Bulimina presli, var. pupoides PARKER and JONES, 1862. Introd. Foram., Appendix, p. 311. Bulimina pupoides Terriat, 1880, Atti dell’ Accad. Pont. ann. xxxiii, p. 193, pl. ii, figs. 30-34. Bulimina pupoides BRADY, 1884. Report on Foram. H. M.S. Challenger. Zool., vol. ix, pp. 400, 401, pl. 1, fig. 15, a, b. Bulimina pupoides WooDWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Sury. Minn., p. 159, pl. iii, fig. 11. Bulimina pupoides. Shell oblong; obtuse, especially at the inferior lateral surface; composed of numerous segments, arranged in an indistinct spiral, and exhibiting a tendency to form three oblique vertical rows; segments remarkably CRETACEOUS FORAMINIFERA. 33 Pleurostomella, Bolivina.] ventricose and prominent ; the anterior one usually more oblong than the rest, from its anterior part not being embraced, as all the preceding ones, by the next segment. Septal plane convex; semilunar. Septal orifice single, placed near the umbilical border of the septal plane, and usually characterized by a curious obliquity at its inner part, owing to the two lips of the orifice not meeting at their umbilical extremites, but passing one behind the other. Texture hyaline; transparent ; when examined after being mounted in Canada balsam, through a high power, it is seen to be perforated by innumerable minute foramina. Wuiii1Amson, (Recent Foraminifera Gt. Brit., p. 62.) Locality. Meeker county, Minnesota; Saline county, Nebraska; South Chicago, Illinois. Of the material examined containing this species, in that from Minnesota it was quite rare; from Nebraska very common, and in that from Illinois, rare. It has also been found in the Post-tertiary of Canada. PLEUROSTOMELLA, Reuss. PLEUROSTOMELLA SUBNODOSA Feuss. PLATE O, FIG. 25. Nodosaria nodosa (pars.) REuss, 1845. Verstein. Bohm. Kreid., pt. 1, p. 28, pl. xiii, fig. 22 (fide Reuss). Dentalina subnodosa (pars.), Id. 1850. Haidinger’s Naturw. Abhandl., vol. iv, p. 24. plate i, fig. 9 (fide Reuss). Pleurostomella subnodosa, Id. 1860. Sitzungsb. d. k. Ak. Wiss. Wien, vol. xl, p. 204, pl. viii, fig. 2, a, b. Pleurostomella subnodosa MARSSON, 1878. Mittheil. Naturw. Vereine Neu-Vorpom. u. Rigen, Jahrg. X, p. 133. Pleurostomella subnodosa BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 412, figs. 12, 13. “D. subnodosa (T.1. f. 9), elongata, subrecta; loculis fere regulariter incres- centibus, parum convexis, ultimo maximo, convexo, breviter acuto ; primo minimo obtusum-sculo; apertura nuda. Long.—1.15 mm.” Reuss. (Haidinger’s Naturw. Abhandl., vol. iv, p, 24, pl. 1, fig. 9.) Test elongated, nearly straight ; chambers quite regularly increasing, slightly convex, the last one the largest, convex, shortly acute ; the first chamber smallest, rather obtuse ; aperture naked. Locality. Saline county, Nebraska ; South Chicago, Illinois. BOLIVINA, d’Orbigny. Bouivina DILATATA Leuss, PLATE ©, FIG. 26. Bolivina dilatata Reuss, 1849. Denkschr. d. k. Akad. Wiss. Wien, vol. i, p. 381, pl. xlviii, fig. 15. Bolivina dilatata TERRIGT, 1880. Atti del? Accad. Pont., ann. xxxili, p. 197, pl. ii, fig. 42. Bolivina dilatata BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 418, pl. lii, figs. 20, 21. Bolivina dilatata. “Testa cuneata, superne dilatata, infra acuta, compressa, punc- —3 34 THE PALEONTOLOGY OF MINNESOTA. [Bolivina. tata, margine acutangula. Loculi numerosi angusti ; recti, parum obliqui; apertura simplex. Long.—0.3—0.4 mm.” Reuss. (Denkschr. d.k. Akad. Wiss. Wien, vol. i, p. 381. A more general description is given in German, of which the following is a translation: B. dilatata, shell, narrow-cuneiform, broad above, acuminated below, but in the middle relatively stout, thinning out gradually toward the sharp margins, punctate ? on the surface. The “chambers” are numerous (11 to 12 on each side), lower, not curved, only a little oblique, scarcely rounded. Locality. Saline county, Nebraska. Botrvina PunoTata d’Orbigny. PLATE ©, FIGS, 27, 28. Bolivina punctata d’ORBIaNY, 1839. Foram. Amer. Merid., p. 61, pl., viii, figs. 10—12. Bolivina antiqua, Id., 1846. Foram. Foss. Vien., p. 240, pl. xiv, figs. 11-13. Grammostomum polystigma EHRENBERG, 1854. Mikrogeologie, pl. xix, fig. 84. Gramnostomum caloglossa EHRENBERG, Ibid., pl. xxv, figs. 17, 18. Bolivina punctata BRADY, 1864. Trans. Linn. Soc. Lond., vol. xxiv, p. 468, pl. xlviii. fig. 9, a, b. Bulimina presli var. (Bolivina) punctata PARKER and JONES, 1865. Phil. Trans., vol. clv, p. 376, pl. xviii, fig. 74. Bolivina elongata HANTKEN, 1875. Mittheil. Jahrb. d. k. ung. geol. Anstalt, vol. iv, p. 65, pl. vii, fig. 14. Bolivina antiqua TERRIGaI, 1880. Atti dell’ Acad. Pont., ann. xxxiii, p. 196, pl. ii, fig. 40. Bolivina punctata MOEBIUS, 1880. Foram. von Mauritius, p. 94, pl. 9, figs. 9, 10. Bolivina punctata BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 417, pl. lii, figs. 18, 19. : Bolivina punctata WoopwaArp and THoMAs, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Sur. Minn., p. 169, pl. iii, fig. 12. B. punctata. “Testa elongata, compressa, conica, antice obtusa, postice acu- minatea, alba, punctata, lateraliter subcarinata; loculis numerosis, obliquis, undulatis, ultimo obtuso ; apertura simplici.” D’Orsreny. (Foram. Amer. Merid., p. 63. Test elongated, compressed, conical, obtuse anteriorly, acuminated posteriorly. white, punctate, sub-carinate on sides, with numerous oblique undulate segments, the last obtuse, aperture simple. Locality. Meeker county, Minnesota; Saline county, Nebraska, and South Chicago, Illinois. Quite rare in all these localities. CRETACEOUS FORAMINIFERA. 35 Lagena.] LAGENID As. Sub-Family LAGENIN &. LAGENA, Walker and Boys. LAGENA ASPERA Leuss. PLATE D, FIG. 1. Lagena aspera Reuss, 1861. Sitzungsb. d. k. Akad. Wiss. Wien., vol. xliv, p. 305, pl. i, fig. 5. Lagena aspera REUSS, 1863. Ibid., vol. xlvi, p. 335, pl. vi, fig. 81. Lagena parkeriana (?) BRADY, 1876. Monogr. Carb. and Perm. Foram., p. 120, pl. viii, figs. 1-5. Lagena aspera SIDDALL, 1878. Proc. Chester Soc. Nat. Sci., pt. 2, p. 48. Lagena aspera BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol ix, p. 457, pl. lvii, figs. 6-12. L. aspera. “Fast kugelig, oben sich wenig verschmilernd und zu keinem schna- bel zuspitzend. Die schalenoberfliche is mit ziemlich gedringt stehenden,, unglei- chen, unregelmissig eckigen Héckerchen bedeckt. Sehr selten.” Reuss. (Sitzb. d. mathem-naturw. cl, xliy, p. 305.) Lagena aspera Reuss. Quite spherical, above narrowed somewhat, but forming no beak. ‘Che surface is covered with moderately crowded, unequal, irregular, angular tubercles. Locality. Saline county, Nebraska. Has been found in the Eocene limestone, Alabama river, Monroe county, below Claiborne, Alabama. LAGENA HISPIDA Feuss. PLATE D, FIG. 2. ‘* Spheerule hispide ”’ SOLDANI, 1798. Testaceographia, vol. ii, p. 53, pl. xvii, v, x. Oolina salentina(?) Costa, 1856. Atti dell’ Accad. Pont., vol. vii, p. 118, pl. xi, figs. 13, 14. Lagena hispida Reuss, 1858. Zeitschr. d. deutsch. geol. Gesellsch., vol. x, p. 434. Lagena hispida Reuss, 1863. Sitzungsb. d. k. Ak. Wiss. Wien, vol. xlvi, p. 335, pl. vi, figs. 77-79. Lagena jeffreysii BRADY, 1866. Report Brit. Assoc. Trans. Sec., p. 70. Lagena hispida JONES, PARKER and BRADY, 1866. Monogr. Foram. Crag, p. 30, No. 15. Lagena hispida BRADY, 1884. Report on Foram. H. M. S. Challenger, Zool., vol. lix, p. 459, pl. lvii, figs. 1-4; pl. lix, figs. 2-5. L. hispida und concinna Reuss, in Zeitschr. d. deutsch, geol. Ges., pag. 484 (nomen), 1858. “Der gewélbte Theil des Gehauses ist in seiner Gestalt sehr veranderlich, bald beinahe kugelig, bald eiférmig oder selbst schmal und lang-elliptisch, beinahe walzenférmig. Nach oben zieht er sich zu einem diinnen réhrigen Schnabel zusam- men, der die halbe Lange des Gehauses einnimmt. Die Oberflaiche ist mit regellos gestellten, aber gedrangten kiirzeren und langeren, dickeren und dtinneren, unregel- missig gestalteten Stachelhéckerchen bedeckt. An manchen Exemplaren, beson- ders den schmal-elliptischen, werden sie sehr klein und schrumpfen zu kurzen Hoéckerchen zuzammen. Revss. (Sitzb. d. mathem-naturw. cl., xlvi, p. 385.) 36 THE PALEONTOLOGY OF MINNESOTA. (Lagena, Nodosaria. The arched part of the shell is very variable in form, sometimes nearly circular, almost egg-shaped or even narrow and long-elliptic, very near cylindriform. To- wards the top it is drawn out into a thin tubular beak, which embraces half the length of the shell. The surface is covered with irregularly disposed, but crowded shorter and longer, thicker and thinner, variously shaped thorny tubercles. In some examples, especially the narrow-elliptical ones, the tubercles are very small and contracted into short monticules. Locality. Northeastern Minnesota. LAGENA FAvosA—PuNCcTATA Brady. PLATE B, FIGS, 3-6. Lagena favosa-punctata BRADY, 1881. Quart. Journ. Mic. Soc., vol. xxi, n.s., p. 62. Lagena favosa-punctata BRADY, 1884. Report on Foram. H. M. 8. Challenger, Zool., vol. ix, p. 473, pl. lviii, fig. 35; pl. lix, figs. 3, 4: pl. 1xi, fig. 2. Lagena favosa-punctata WoopwARbD and THomAsS, 1885. Thirteenth Annual Report, Geol. Nat. Surv. Minn., p. 170, pl. iv, figs. 32, 33, 34, 38. “Test ecto- or ento-solenian, shape variable ; surface areolated or reticulated, with a conspicuous orifice or perforation in the middle of each area or depression. Length th inch (0.54 mm.) or less.” Brapy, Joc. cit. Locality. Meeker county, Minnesota. Found only in the material from Minnesota. NODOSARIN Zz. NODOSARIA, Lamarck. Noposaria (D) communis d’Orbigny. PLATE D, FIGS. 7, 8. Nautilus rectus MONTAG, 1803. Test. Britann., p. 197; supplem. p. 82, t. 19, figs. 4-7. Nautilus subarcuatus MONTAG, 1803. Test. Britann., p. 198, t. 6, fig. 5. Nodosaria (Dentalina) communis @’ORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 254, No, 35. Dentalina carinata @WORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 255, No. 39. Nodosaria levigata NILSSON, 1827. Petrificata Suecana, p. 8, vol. ix, fig. 2. Dentalina lorneiana @’ORBIGNY, 1831. Foram. Craie bl. Paris; Mem. Soc. Geol. France, vol. vi, p. 14, pl. i, figs. 8, 9. Dentalina nodosa @ORBIGNY, 1839. Foram. Craie bl. Paris; Mem. Soc. Geol. France (2) vol. iv, p. 14, pl. i, figs. 6, 7. Dentalina gracilis, Id., Ibid., vol. vi, p. 14, pl. i, fig. 5. Dentalina communis, Id., Ibid., (1840) p. 18, pl. 1, fig. 4. Nodosaria radicularis Miinst., Rom., 1838. Nord. tert. Meeressand; Leonh. u. Bronn’s, Jhrb., 1838, p. 382, pl. 3, fig. 3. Nodosaria linearis ROm., 1842. Vert. nordd. Kreidegeb., p. 95, pl. xv, fig. 5. Nodoswria nodosa REusS, 1845. Bohm. Kreide 1, p. 28, pl. xiii, fig. 22. Nodosavria gracilis, Id., Ibid., p. 27, pl. viii, fig. 6. Nodosaria lorneiana, Id., Ibid., p. 27, pl. viii, fig. 5. Nodosaria communis, Id., Ibid., p. 28, pl. xii, fig. 21. Nodosaria legumen, Id., Lbid., p. 28, pl. xiii, figs. 23, 24. CRETACEOUS FORAMINIFERA. 37 Nodosaria communis. | Dentalina inornata @ORBIANY, 1846. For. Foss. Vien., p. 44, pl. i, figs. 50, 51. Dentalina badensis, Id., Ibid., p. 44, figs. 48, 49. Dentalina brevis, Id., lbid., p. 48, pl. ii, figs, 9, 10. Dentalina elegans, Id., Ibid., p. 45, pl. i, figs. 52-56. Dentalina seripta, 1d., Ibid., p. 51, pl. ii, figs. 21-23. * Dentalina punctata, Id., Ibid., p. 49, pl. ii, figs. 14, 15. Dentalina verneuilli, Id., Ibid., p. 48, pl. ii, figs. 7, 8. Dentalina pauperata, Id., Ibid., p. 46, pl. i, figs. 57, 58. Dentalina boneana, Id., Ibid., p. 47, pl. ii, figs. 4-6. Dentalina consobrina, Id., Ibid., p. 46, pl. ii, figs. 1-3. Dentalina inermis CzszEK, 1847. Haidinger’s Naturw. Abhandl., vol. ii, p. 139, pl. xii, figs. 3-7. Dentaline ferstliana, Id., Ibid., p. 140, pl. xii, figs. 10-13. Dentalina cingulata, Id., Ibid., p. 139, pl. xii, figs. 8, 9. Marginul contraria, Id., Ibid., p. 140, pl. xii, figs. 17-20. Dentalina chrysalina CorRN., 1848. Norw. Foss. Micros. Cret.; Mem. Soc. Geol. France,(2) vol. iii, p. 251, pl. 1, fig. 21. Dentalina intermedia, Id., Ibid., p. 251, pl. i, fig. 20. Dentalina antenna, Id., Ibid., p. 250, pl. i, fig. 19. Dentalina gracilis ALTH., 1849. Umgeb. Lemb.; Haid. Nat. Abh., 3, 2, p. 269, pl. xiii, fig. 27. Dentalina mutabilis BAILEY, 1850. Examin. of Soundings ; Smithson. Contrib. to Knowledge, vol. ii, art. 3, pl. x, fig. 7. Dentalina annulata Rewss, 1850. Kreide Lemberg ; Haid. Nat. Abh., 4, 1, p. 26, pl. i, fig. 13. Dentalina acus, I1d., Ibid., p. 27, pl. i, fig. 15. Marginul elongata, Id., Ibid., p. 28, pl. i, fig. 17. Marginul apiculata, Id., Ibid., p. 28, pl. i, fig. 18. Dentalina obtusata Reuss, 1851. Tert. Sch. Oberschlesien; Zeitschr. deutsch. geol. Ges., p. 151, pl. viii, fig. i. Dentalina emaciata Reuss, 1851. Sept. Thon von Berlin ; Zeitschr. deutsch. geol. Ges., 3, p. 63, pl. iii, fig. 9. Dentalina acuticauda Reuss, 1851. Lbid., p. 62, pl. iii, fig. 8. Dentalina nitens Costa, 1854. Pal. d. Reg. Nap., 2. p. 165, pl. xii, fig. 26. Marginul torulosa Cost 4y 1854. Pal. d. Reg. Nap., 2, p. 185, pl. xii, fig. 15. Dentalina prelonga Costa, 1854. Pal. d. Reg. Nap., 2, p. 163, pl. xii, fig. 21. Dentalina nodosa, Id., Ibid., p. 164, pl. xii, fig. 8. Dentalina badenensis, Id., Ibid., p. 174, pl. xvi, fig. 28. Marginul inversa, Id., Ibid., p. 189, pl. xii, fig. 16. Dentalina megalopolitana Reuss, 1855. Kreidegeb. Mecklenburg ; Zeitschr. deutsch. geol. Ges., vol. vii, p. 267, pl. viii, fig. 10. Dentalina tenuicollis, Id., Ibid., p. 267, pl. viii, fig. 11. Dentalina plebeja, Id., Ibid., p. 267, pl. viii, fig. 9. Dentalina verneuilli BORNEMAN, 1855. Sept. Thon. Hermsdorf; Zeitschr. deutsch. geol. Ges., vol. vii. p. 324, pl. xiii, fig. 8. Dentalina consobrina, Id., Ibid., p. 323, pl. xiii, figs. 1-4. Dentalina pauperata, Id., Ibid., p. 324, pl. xiii, fig. 7. Marginul tenuis, Id., Ibid., p. 326, pl. xiii, fig. 14. Dentalina adunca Costa, 1855. Foram. Marna Blu. Vaticano; Mem. Nap., vol. ii, p. 117, pl. i, fig. 1. Dentalina nepos, Id., Ibid., p. 117, pl. i, fig. 2. Dentalina haidingeri NEUGEB., 1856, Foram. Stichosteg. Ob. Lapug.; Wien Ak. Dkschr. 12. 2, p. 85, pl. iii, fig. 12. Dentalina perversa, Id., Ibid., p. 80, pl. ii, fig. 8. Dentalina reussi, Id., Ibid., p. 85, pl. iii, figs. 6-7, 17. Dentalina perscripta EGGER, 1857. Miociin. Ortenburg ; Leonh. u. Bronn’s Jahrbuch, 1857, p. 307, pl. xV, figs. 30, 31. Dentalina acuminata Reuss, 1859. Westphil. Kreide; Wien, Ak. Sitz.—Ber., vol. 40, p. 181, pl. i, fig. 7. Dentalina tenuicaudata, Id., Ibid., p. 182, pl. ii, fig. 3. Dentalina commutata, Id., Ibid., p. 183, pl. ii, fig. 4, Dentalina pugiunculus, Id., Ibid., p, 183, pl. iii, fig. 9. Dentalina communis PARKER and JONES, 1860. Foram. Chellast.: Quart. Journ. Geol. Soc., vol. xvi, p. 453, pl. xix, fig. 25. Dentalina pauperata, Id., Ibid., p. 453, pl. xix, fig. 22. Dentalina colligata REuUsS, 1861. Griinsand von New Jersey; Wien. Ak. Sitz.—Ber., 1, 44, p. 334, pl. vii, fig. 4. Dentalina linearis Reuss, 1862. Nordd. Hils u. Gault; Wien. Ak. Sitz.—Ber., 1, 46, p. 42, pl. ii, fig. 15. 38 THE PALEONTOLOGY OF MINNESOTA. (Nodosaria communis. Dentalina deflexa, Id., Ibid., p. 43, pl. ii, fig. 19. Nodosoria nuda, Id., Ibid., p. 38, pl. ii, figs. 8, 9. Dentalina fasciata SEQUENZA, 1862. Rhizopod. d. Catania; Acad. Gioenia Atti,(2) vol. xviii, p. 12, Disa, fig. 1. Dentalina indifferens REUSS, 1863. Sept. Thon Offenbach; Wien. Ak. Sitz.—Ber., 1, 48, p. 44, pl. ii, figs. 15, 16. Dentalina communis PARKER and JONES, 1865. North Atlantic and Arctic Oceans; Phil. Trans., p. 342, pl. xiii, fig. 10. Dentalina consobrinad PARKER and JONES, 1865. North Atlantic and Arctic Ocean; Phil. Trans., p. 342, pl. xvi, fig. 3. Dentalina equalis KARRER, 1865. Foram Griinsandstein N. Zeeland; Novara Reise, geol. Theil, 1, 2, p. 74, pl. xvi, fig. 1. Dentalina inornata REwss, 1865. Sept. Thon Offenbach ; Wien. Ak. Sitz.—Ber., 1, 48, p.45, pl. ii, fig. 18. Nodosaria vermiculum Reuss, 1865. Foram. deutsch. Sept. Thon; Wien. Ak. Dkschr., 1, 25, 1, p. 133, \ pl. ii, figs. 14, 15. Nodosaria approximata, Id., Ibid., pl. ii, fig. 22. Dentalina communis sub-var. pauperata PARKER and JONES, 1866. Crag. Foram.; Pal. Soc., vol. xix, p. 58, pl. i, figs. 13, 20. Nodosaria neugeboreni SCHWAGER, 1869. Novara-Exped., geol. Theil, vol. ii, p. 232, pl. vi, fig. 67. Nodosaria gracilescens, Id., Ibid., p. 234, pl. vi, fig. 70. Nodosaria pupiformis KARRER, 1867. Foram. Fauna Osterreich ; Wien. Ak. Sitz.—Ber., 1, 55, p. 354, pl. i, fig. 5. Dentalina aherculea GéMBEL, 1868. Nordalp. Eocan; Abh. k. Bayr. Ak., 1, 10, 2, p. 621, pl. i, fig. 34. Dentalina linearis, Id., Ibid., p. 622, pl. i, fig. 36. Dentalina glandulifera, Id., Ibid., p. 622, pl. i, fig. 37. Dentalina fusiformis, Id., Ibid., pl. 621, pl. i, fig. 35. Dentalina korynephora Gt MBEL, 1869. Foram. St. Cassin u. Raibl. Sch.; Oster. geol. Reichsanst., Jharb. xix, p. 176, pl. v, fig. 1. Dentalina transmontana, Id., Ibid., p. 177, pl. v, fig. 17. Dentatina inorta TERQUEM, 1870, Foram. du Syst. Oolith., 3 ™*e Mem., p. 262, pl. xxvii, figs. 26-34. Nodosaria peracuta REUSS, 1873. Geinitz, Elthalgeb. Sachsen, 2, p. oD li, fig. 21. Nodosaria annulata, Id., Ibid., p. 85, pl. ii, figs. 19, 20. Dentalina budensis HANTKEN, 1875. Mittheil. Jahrb. d. k. ung. geol. Anstalt, vol. iv, p. 34. pl. xiii, figs. 7, 12. Dentalina boneana HANTKEN, 1875. Foram. lay. Szab. Sch.; Mittheil. Jahrb. d. k. ung. geol. Anstalt, p. 34, pl. xii, figs. 11, 19. Dentalina communis BRADY, 1876. Carbonif., and Perm. Foram.; Pal. Soc., vol. xxx, p, 127, pl. x, figs. Ty, 1G} Nodosaria clava KARRER, 1878. Foram. Luzon; Bolet. Comis. Mapa Geol. del Espana, 7, 2, p. 16, pl. H, fig. 11. Nodosaria communis Gors, 1882. Reticularian Rhizopoda of the Caribbean Sea; K. S. Vet. Akad. Hand., vol. xix, p. 26, pl. i, figs. 11-16. Nodosaria legumen, Id., Ibid., p. 34, pl. ii, figs. 20-31. Nodosaria (D) communis BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 504, pl. Ixii, figs. 19-22. ; “ N. (D.) communis, testa elongata, arcuata, levigata ; postice acuminata, caudata ; loculis numerosis, obliquis, ultimo supra convexo, acuminato, primo convexo ; suturis subcomplantis; apertura minima, radiata.” D’Orpreny. (1840, Mém. Soe. Géol. de France, vol. iv, p. 18.) N.(D.) communis, shell elongated, arched, smooth ; posteriorly acuminate, caudate ; numerous chambers, oblique, last very convex, acuminate, first convex ; sutures sub- complanate ; very small aperture radiate. Locality. Saline county, Nebraska. This species seems to be very rare in the western Cretaceous ; in the material examined we found only one perfect specimen and two fragments, It is very abundant and well preserved in the Cretaceous of New Jersey, at Timber creek and Mullica hill. CRETACEOUS FORAMINIFERA. 39 Uvigerina.] UVIGERINA, d’Orbigny. UvigERINA ASPERULA Czjzek. PLATE D, FIG. 10. Uvigerina asperula CzJZEK, 1847. Haidinger’s Naturw. Abhandl., vol. ii, p. 146, pl. xiii, figs. 14, 15. Uvigerina orbigniana, Id., Ibid., p. 147, pl. xiii, figs. 16, 17. Uvigerina gracilis REUSS, 1851. Zeitschr. d. deutsch. geol. Gesellsch., vol. iii, p. 77, pl. v, fig. 39. Uvigerina gracilis BORNEMANN, 1865. Ibid., vol. vii, p. 343, No. 1. Uvigerina hispida SCHWAGER, 1866. Novara-Exped., geol. Theil, vol. ii, p. 249, pl. vii, fig. 95. Uvigerina asperula SEGUENZA, 1880. Atti Accad. dei Lincei, ser. 8, vol. vi, pp. 146, 226, 307. Uvigerina asperula BRADY, 1884. Report on Foram. H.M.S. Challenger, Zool., vol. ix, p. 578, pl. Ixxv, figs. 6-8. “U. testa oblonga, antice et postice acuminata, asperula et longitudinaliter costulata’; loculis convexis, globulosis, ineequalibus; apertura fistulosa, marginata. Diam. $ mill. Long. 14 mill.” Czszex. (Haidinger’s Naturw. Abhandl., vol. 1, p. 146) Shell oblong, anteriorly and posteriorly acuminate, longitudinally ribbed, spinulose undulate, chambers convex, globose, unequal, aperture tubular, margined. Locality. Saline county, Nebraska. Very rare. Uvicrrina canariensis d’Orbigny. PLATE D, FIG. 9. ‘* Testee pineiformes minuscule’ SOLDANT, 1798. Testaceographia, vol. ii, p. 18, pl. iv, figs. E, F, G, H. Uvigerina nodosa var B, d’ORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 269, No. 3. Uvigerina canariensis, Id., 1839. Foram. Canaries, p. 138, pl. i, figs. 25-27. Uvigerina urnula @ORBIGNY, 1846. Foram. Foss. Vien., p. 189, pl. xi, figs. 21, 22. Uvigerina irregularis BRADY, 1865. Nat. Hist. Trans. Northd.and Durham, vol.i, p. 100, pl. xii, fig. 5. Uvigerina proboscidea SCHWAGER, 1866. Novara-Exped., geo]. Theil, vol. ii, p. 250, pl. vii, fig. 96. Uvigerina farinosa HANTKEN, 1875. Mittheil. Jahrb. d. k. ung. geol. Anstalt, vol. iv, p. 62, pl. vii, fig. 6. Uvigerina canariensis BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 573, pl. lxxiy, figs. 1-3. Uvigerina canariensis WOODWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 171, pl. iv, fig. 37. “U, testa oblongo-conica, punctata, albida ; spira conica, anfractibus quinis minime convexis; loculis convexis per quamque spiram trinis; apertura rotunda ; siphone brevi.” D’Orspieny. (Foraminifera Canaries, p. 138.) Test oblong conical, punctate, whitish with a conical spire of five whorls slightly convex, segments convex, three to each whorl of the spire, aperture round, siphon short. - Locality. Meeker county, Minnesota; Saline county, Nebraska. Very rare in Minnesota and Ne- braska. Has also been found in the borings from an artesian well at Atlantic City, New Jersey. 40 THE PALEONTOLOGY OF MINNESOTA. (Globigerina. GE@QBIG EN DAs: GLOBIGERINA, d’Orbigny. GLOBIGERINA BULLOIDES d’Orbigny. PLATE D, FIGS. 11-17. * Polymorpha Tuberosa et Globulifera” SOLDANT, 1791. Testaceographia, vol. i, pt. 2, p. 117, pl. cxxiii, figs OP: Testce tuberosee, etc., Id., 1798. Ibid., vol. ii, p. 20, pl. vi, figs. dd, ee. Globigerina bulloides @ORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 277, No. 1, Modéles, No. 17 (young) and No. 76. Globigerina bulloides, Id., 1889. Foram, Amér. Merid., p. 37. Globigerina bulloides, Id., 1839. Foram. Canaries, p. 182, pl. ii, figs. 1-3, 28. Globigertna hirsuta, Id., Ibid., p. 133, pl. ii, figs. 4-6. Globigerina siphonifera, Id., 1839. Foram. Cuba, p. 95, pl. iv, figs. 15-18. Globigerina bulloides, Id., 1846. Foram. Foss. Vien., p. 163, pl. ix, figs. 4-6. Globigerina concinna Reuss, 1849. Denkschr. d. k. Akad., Wiss. Wien., vol. i, p. 373, pl. xlvii, fig. 8. Globigerina diplostoma, Id., [bid., p. 378, pl. xlvii, figs. 9, 10. Globigerina depressa HHRENBERG, 1854. Mikrogeologie, pl. xix, fig. 92. Globigerina foveolata (pars.), Id., Ibid., pl. xxii, fig. 74. Globigerina crete EHRENBERG, 1854. Mikrogeologie, pl. xxvi, fig. 44; pl. xxx, fig. 38. Globigerina stellata, Id., Ibid., pl. xxvi, fig. 45. Globigerina ternata EHRENBERG, 1854. Mikrogeologie, pl. xxxv B, figs. 5, 6. Planulina porotetras, Id., 1854. Ibid., pl. xx, II, fig. 16. Planulina pertusa, Id., Ibid., pl. xxii, fig. 75. Planulina stigma, Id., Ibid., pl. xxv, fig. 29. Rotalia vudis, Id., Ibid., pl. xxiv, figs. 35, 36. Rotalia leptospira, Id., Ibid., pl. xxiv, fig. 39. Rotalia senaria (pars.), Id., Ibid., pl. xxiv, fig. 40. Ptygostomum orphei, Id., Ibid., pl. xxxv B, figs. 1, 2. Phanerostomum atlanticum, Id., Ibid., pl. xxxv B, figs. 3, 4. Globigerina bulloides KéBLER and ZWINGLI, 1866. Neujahrsblatt, vy. d. Birgerbib. in Winterthur, pt. 2, p. 22, pl. iii, figs. 30, 31. Globiyerina taminensis, Id., Ibid., p. 24, pl. iii, fig. 26. Globigerina bulloides GimMBEL, 1868. Abh. d. k. bayer. Akad. d. Wiss., II, cl. vol. x, p. 661, pl. ii, figs. 106 a, b. Globigerina alpigena (?), Id., Ibid., p. 661, pl. ii, fig, 107. Globigerina eoceena, Id., Ibid., p. 662, pl. ii, fig. 109. Planulina mauryana EHRENBERG, 1873. Abhandl. d. k, Akad. Wiss. Berlin (1872), p. 388, pl. iii, fig. 1- Planulina globigerina, Id., Ibid., p. 388, pl. iii, fig, 3. Planulina meqalopentas, Id., Ibid., p. 388, pl. iv, fig. 7. Pylodexia platyletras, Id., Ibid., p. 388, pl. iii, fig. 14. Aristerospira omphalotetras, Id., Ibid., p. 388, pl. ili. fig. 15. Globigerina detrita TERQUEM, 1875. Anim. sur la Plage de Dunkerque. fasc. i, p. 31, pl. iv, fig. 4, a-c. Globigerina bulloides TERQUEM, 1875. Anim. surla Plage de Dunkerque, fasc. i, p.31, pl. iv, fig. 5, a-b. Globigerina bulloides H1LGARD and Hopxrns, 1878. Rec. of the Alluvial Basin of the Miss. river, pp. 18, 42, pl. ii, figs. 70, 71, 72. Globigerina bulloides BRADY 1879. Quart. Journ. Micr. Soc., vol. xix, n. s., p. 71. Globigerina bulloides BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 593, pl. Ixxix, figs. 3-7. Globigerina bulloides ANDRE®, 1884. Beitrag zur Kenntniss des Elsasser Tertiars, II Theil, pl. ix, figs. 1, 2. Globigerina bulloides WoopwArbd and THomaAs, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 172, pl. iii, fig. 13. CRETAQEOUS FORAMINIFERA. 41 Globigerina.] { “Test spiral, subtrochoid; superior face convex, inferior more or less convex but with deeply sunken umbilicus, periphery rounded, lobulated ; adult specimens composed of about seven globose segments, of which four form the outer convolu- tion; the apertures of the individual chambers opening independently into the umbilical vestibule. Diameter sometimes ,,th inch (0.638 mm.) but oftener much less.’ Brapy Joc. cit. Locality. Meeker county, Minnesota; Saline county, Nebraska; South Chicago, Illinois. Common in Nebraska; not quite so common in Minnesota; rare in South Chicago. The most common of all our living forms, and may be found anywhere along our seacoast, also as a fossil in the ‘‘ Eolian sand” from the Smoky Hill river, near Lindsborg, Kansas. GLOBIGERINA CRETACEA d’Orbigny. PLATE D, FIGS. 18, 19. Globigerina cretacea d’ORBIGNY, 1840. Mem. Soc. Geol. France, vol. iv, p. 34, pl. iii, figs. 12-14. Globigerina faveolota (pars) EHRENBERG, 1854. Mikrogeologie, pl. xxiv, fig. 49. Globigerina libani EHRENBERG, Ibid., pl. xxv, fig. 30. Planulina pachyderma, Id., Ibid., pl. xxv, fig. 31. Rotalia pertusa, Id., Ibid., pl. xxiv, fig. 41. Rotalia aspera, Id., Ibid., pl. xxvii, figs. 57, 58; pl. xxviii, figs 42; pl. xxxi, fig. 44. Rotalia globulosa, Id., Ibid., pl. xxvii, fig. 60; pl. xxviii, figs. 40, 41; pl. xxxi, figs. 40, 41, 43. Rotalia densa, Id., Ubid., pl. xxvii, fig. 62. Rotalia quaterna, Id., Ibid., pl. xxvii, fig. 533; pl. xxviii, fig. 34. Rotalia rosa, Id., Ibid., pl. xxvii, fig. 54. Rotalia pachyomphala, Id., Ubid., pl. xxvii, fig. 55. Rotalia tracheotetras, 1d., Ibid., pl. xxvii, fig. 35. Rotalia perforata, Id., Ibid., pl. xxviii, fig. 36; pl. xxix, fig. 2. Rotalia protacmea, Id., Ibid.. pl. xxviii, flg. 37. Rotalia laxa, Id., Ibid., pl. xxviii, fig. 38 ; pl. xxix, fig. 1; pl. xxxi, fig. 42. Rotalia centralis, Id., Ibid., pl. xxviii, fig. 39. Globigerina cretacea BRADY, 1879. Quart. Journ. Micr. Soe., vol. xix, n. s., p. 285. Globigerina cretacea BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 596, pl. 1xxxii, fossil specimens, fig. 11, a-c. Globigerina eretacea WODWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 171, pl. iii, figs. 14-16: iv, fig. 19. “Test rotaliform, much compressed; superior face flattened or only slightly convex, inferior side depressed towards the centre and excavated at the umbilicus, periphery obtuse and lobulated ; composed of about three tolerably distinet convolu- tions, the outermost consisting of from five to seven segments ; segments relatively small, subglobular ; apertures opening into an umbilical vestibule. Diameter=,th inch (0.5 mm.)” Bravpy Joe. cit. Locality. Meeker county, Minnesota; Saline county, Nebraska; South Chicago, Illinois, and Little Fork river, near Rainy lake, Minnesota. It is found very abundant in the Boulder clay of Minnesota, but the specimens are quite fragmentary, while those in the Nebraska and Illinois clays are more numerous and in a much better state of preservation. Dr. G. M. Dawson, in 1874, found it in the Cretaceous clays from Manitoba. 42 THE PALEONTOLOGY OF MINNESOTA. (Globigerina. GLOBIGERINA MARGINATA Jeuss. PLATE D, FIGS. 20, 21, Rosalina marginata Reuss, 1845. Verstein. bohm. Kreid., pt. i, p. 36, pl. xiii, fig. 47. Rosalina marginata JONES, 1853. Ann. and Mag. Nat. Hist., ser. 2, vol. xii, p. 241, pl. ix, fig. 7. Rosalina marginata Reuss, 1854. Denkschr. d. k. Akad. Wiss. Wien, vol. vii, p. 69, pl, xxvi, fig. 1. Discorbina marginata, Id., 1854. Sitzungsb. d. k. Akad. Wiss. Wien, vol. vii, p. 12, No. 2. Globigerina marginata PARKER and JONES, 1865. Phil. Trans., vol. cly, p. 367. Rotalia marginata GUMBEL, 1870. Sitzungsb. d. k. bayer, Akad. Wiss., vol. ii, pp. 283, 287. Globigerina marginata Reuss, 1874. Das Elbethalgebirge in Sachsen, 2ter Theil, p. 112, No. 2. Globigerina marginata BRADY, 1879. Quart. Journ. Micr. Soc., vol. xix, n. s., p. 74. Globigerina marginata BRADY, 1884. Report on Foram. H. M.S. Challenger, Zool., vol. ix, p. 597, wood cut, fig. 17. Globigerina marginata WOODWARD and THomAs, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., p. 174, pl. iv. figs. 20-22. “Test rotaliform, much compressed ; superior face convex, inferior face also convex, but with a sunken umbilical recess, peripheral edge thin or subcarinate ; segments numerous, five or six in the last convolution, the outer margin of each seg- ment exhibiting a well-marked narrow border ; apertures opening into the umbilical vestibule. Surface of living specimens beset with spines. Diameter 2,th to th inch (0.5 to 1 mm.)” Brapy loc. cit. Locality. Meeker county and Northeastern Minnesota ; Little Fork river, Saline county, Nebraska ; South Chicago, Illinois. This species in Minnesota is quite well represented, and in good state of preservation, while in Nebraska they are common but fragmentary. We are in some doubt about this species, it resembles so closely in some respects G. linnceeana, while in others Pulvinulina menardii; but we feel quite satisfied to favor G. marginata REuss. GLOBIGERINA sAccuLirERA H, B. Brady. PLATE D, FIG. 22. Globigerina helicina CARPENTER, 1862. Introd. Foram., pl. xii, fig. 11. Globigerina sacculifera BRADY, 1877. Geol. Mag., dec. II, vol. iv, p. 535. Globigerina sacculifera BRADY, 1879. Quart. Journ. Micr. Soc., vol. xix, n. s., p. 73. Globigerina sacculifera BRADY, 1884. Report Foram. H. M.S. Challenger, Zool., vol. ix, p. 604, pl. ; 1xxx, figs. 11-17; pl. Ixxxii, fig. 4. “Test oblong, compressed, rotaliform ; segments few, usually five to seven in number, of which four generally compose the final convolution ; earlier chambers small and subglobular ; the ultimate segment, and sometimes also the penultimate, elongated radially and more or less pointed at the peripheral extremity. Aperture variable, consisting of a single large opening at the inferior umbilical margin of the terminal segment, and one or sometimes several round orifices in the sutural depressions of the superior face. Pelagic specimens spinous externally. Longer diameter ,th inch (1 mm.) more or less.’ Brapy loc. cit. Locality. Northeastern Minnesota. We found but one specimen in the boulder clays, but it closely resembled, in so many respects, those figured by Carpenter and Brady, that we are quite satisfled that it is the same species. CRETACEOUS FORAMINIFERA. 43 Orbulina.] ORBULINA, d’Orbigny. OrBuLina uNnIveRSA d’Orbigny. PLATE D,. FI@S. 23-27. ‘‘Polymorpha spherule vitree,”’ SOLDANI, 1791. Testaceographia, vol. i, pt. 2, p. 116, pl. cxix, figs. I-N. Orbulina universa d’ ORBIGNY, 1839. Foram. Cuba, p. 3, pl. i, fig. 1. Orbulina universa, Id., 1839. Foram. Canaries, p. 122, pl. i, fig. 1. Miliola (Monocystis) arcella EHRENBERG, 1854. Mikrogeologie, pl. xxx, fig. 1. Miliola spherula, Id., Ibid., pl. xxxi, fig. 1, a, b, c. Orbulina granulata var. atva Costa, 1856. Atti dell’ Accad. Pont,, vol. vii, p. 116, pl. xi, fig. 2. Orbulina granulata var. areolata, Id., Ibid., p. 117, pl. xi, fig. 4. Orbulina universa, Id., Ibid., p. 114, pl. xi, fig. 5. Orbulina universa WILLIAMSON, 1858. Rec. Foram. Gt. Br., p. 2, pl. 1, fig. 4. Orbulina universa POURTALES, 1858. Amer. Jour. Sci., ser. 2, vol. xxvi, p. 96. Orbulina universa BRADY, 1859. Quart. Journ. Micr. Soc., vol. xix, n.s., p. 75. Orbulina punctata TERQUEM, 1862. Foram. du Lias, 2ieme mem., p, 432, pl. v, fig. 5. Globigerina (Orbulina) universa OWEN, 1867. Journal Linn. Soc. Lond., vol. ix, Zool., p. 149, pl. v, fig. 1. Globigerina (Orbulina) continens, Id., Ibid., figs. 3, 4. Globigerina (Orbulina) acerosa, Id., Lbid., fig. 2. Orbulina universa STOHR, 1876. Boll. R. Com. Geol. D’ Ital., p. 463. Orbulina universa SCHWAGER, 1877. Boll. R. Com. Geol. D’ Ital., p. 20, pl. fig. 45. Orbulina universa HILGARD and HOPKINS, 1878. Rec. of the Alluvial Basin of the Mississippi river, pp. 13, 39, pl. ii, fig. 73. Orbulina universa SCHACKO, 1883, Wiegmann’s Archiv fur Natur., Jahrg. xlix, p. 428, pl. xiii, fig. 1. Orbulina universa SCHLUMBERGER, 1884. C. R. vol. xcviii, pp. 1002-1004, figs. 1, 2. Orbulina universa BRADY, 1884. Report on Foram., H. M. &. Challenger, Zool., vol. ix., p. 608, pls. Ixxvili; Ixxxi, figs. 8-26; pl. Ixxxii, fig. 1-3. Orbulina universa WOODWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. Nat. Hist. Surv. Minn., pp. 174, 175, pl. iv, figs. 25-31. Generic character, Shell free, regular, spherical, hollow ; perforated by innum- erable very minute foramina, visible only under a high magnifying power; septal orifice single, small, situate at some point on the periphery of the shell; without any marginal projection ; often invisible. Specific character. “Spherical; parietes minutely granular, of a pale grayish- yellow hue. Texture finely arenaceous.* Septal aperture small, normally round, but usually irregular, and sometimes entirely closed up by the inspissated gelatinous sarcode, so as to be invisible. Diam. -,-, inch.”** Locality. Meeker county, Minnesota; Saline county, Nebraska; Calumet, South Chicago, Illinois. In Minnesota it is common, in Nebraska and South Chicago rare. This species was found in the Post- pliocene by Prof. Eugene W. Hilgard and Dr. F. V. Hopkins, in their “‘ investigation of the microscopic character of the strata of dark-colored, brown or blue clays occurring in the borings of the blue ‘delta clay’ which is found almost everywhere in the delta coast region of Louisiana and Mississippi.”+ It is a very common species. *We find by further examination, that the texture is not finely arenaceous, as stated in the description, but calcareous and similar in every respect to its closely allied species Globigerina bulloides. **Williamson’s Recent Foraminifera G. B., 1857. +Reclamation of the Alluvial Basin of the Mississippi River, p. 12, 1878. 44 THE PALEONTOLOGY OF MINNESOTA. [Anomalina, Pulvinulina. Sub-Family ROTALIN A. ANOMALINA, d’Orbigny. ANOMALINA AMMONOIDES [euss, sp. PLATE D, FIGS. 28, 29. Rosalina ammonoides REUSS, 1845. Verstein. fohm. Kreid., pt. 1, p. 36, pl. xii, fig. 66: pl. viii, fig. 53. Rosalina ammonoides, Id., 1850. Haidinger’s Naturw. Abhandl., vol. iv, p. 36, pl. iv, fig. 2. Nonionina bathyomphala, Id., 1862. Sitzungsb. d. k. Ak. Wiss. Wien, vol. xlvi, p. 95, pl. xiii, fig. 1, a, b. Rosalina weinkauffii, Id., 1863. Ibid., vol. xlviii, p. 68, pl, viii, fig. 97. Rosalina maorica STACHE, 1864. Novara-Exped., geol. Theil, vol. i, p. 282, pl. xxiv, fig. 32. Rosalina orbiculus, Id., Ibid., p. 285, pl. xxiv, fig. 34. Planorbulina ammonoides PARKER and JONES, 1865. Phil. Trans., vol. clv, p. 379. Discorbina ammonoides REUSS, 1865. Sitzungsb. d. k. Ak. Wiss. Wien, vol. lii, p. 456, No. 5. Rotalia capitata GUMBEL, 1868. Abhandl. d. k. bayer. Akad. Wiss., II, cl. vol. x, p. 653, pl. ii, fig. 92. Rotalia ammonoides, 1d,, 1870. Sitzungsb. d. k. bayer. Akad, Wiss., p. 283. Planorbulina (Anomalina) ammonoides JONES and PARKER, 1872. Quart. Journ. Geol. Soc., vol. xxviii, p. 106; table, p. 109. Planorbulina ammonoides REUss, 1874. Das Elbthalgebirge in Sachsen, 2/er Theil, p. 114, pl. xxiii, fig. 9. Anomalina ammonoides BRADY, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, pp. 672, 673, pl. xciv, figs. 2, 3. “The shell is generally much compressed, and nearly equally convex on the two sides ; the peripheral edge is round, andthe aperture is placed almost symmetrically in the median line. Some specimens are depressed at both umbilici, others are umbonate at one or both ; sometimes the earlier convolutions are visible to a nearly equal extent on both faces. The coarse perforation of the shell wall is usually more conspicuous on the inferior than on the superior face.” Brapy loc. cit. Locality. Saline county, Nebraska, and South Chicago, Illinois. Anomalina ammonoides is a very common Cretaceous foraminifer in Europe: in America we believe this is the first time it has been noticed. PULVINULINA, Parker and Jones. Putvinutina HAvERI @’Orbigny, sp. PLATE E, FIG. 34. Rotalina haverii VORBIGNY, 1846. Foram. Foss. Vien., p. 151, pl. vii, figs. 22-24. Pulvinulina haverii PARKER and JONES, 1865. Phil. Trans., vol. clv, p. 393. Pulvinulina budensis HANTKEN, 1875. Mittheil. Jahrb. d. k. ung. geol. Anstalt, vol. iv, pl. ix, fig. 5. (Pulvinulina brongniarti, at p. 78). Pulvinulina hauerii BRADY, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 690, pl. evi, figs. vi, vii. “P. hauerii. Testa ovata-convexa levigata, subtus convexa, umbilicata ; spira convexiuscula : anfractibus tribus externé rotundatis ; loculis convexo. Diam. + mill,” D’Orzsiany. (Foram. Foss. Vien., p. 151, pl. vii, figs. 22-24.) P. hauerii. Shell ovate-convex, smooth, convex below, umbilicate ; spire some- what convex, three whorls externally rounded, chambers convex. Diam. 4 mill. Locality. Wittle Fork river near Rainy lake, Northeastern Minnesota. CRETACEOUS FORAMINIFERA. 45 Pulvinulina, Operculina.] PuLvinuLInA MENARDIL d’Orbigny, sp. PLATE E, FIG. 33. Rotalia menardii VORBIGNY, 1826. Ann. Sci. Nat.. vol. vii, p. 273, No 26; Modele No. 10. Rotalina cultrata VORBIGNY, 1839. Foram. Cuba, p. 76, pl. v, figs. 7-9. Rotalia canariensis VORBIGNY, 1844. Foram. Canaries, p. 130, pl. i, figs. 34-36. ?Rotalina spinimargo Reuss, 1849. Neue Foram. Osten. tert. Beck.; Wien. Ak. Dkschr. 1. 1. p. 371, pl. 47, fig. 1. : Rotalina cultrata BAILEY, 1851. Smithsonian Contrib., vol. ii, art. 8, p. 11, figs. 14-16. Planulina incurvata, EHRENBERG, 1854. Mikrogeologie, pl. xxvi, fig. 42. Planulina membranacea, Id., lbid., pl. xxvi, fig. 43. Pulvinulina repanda var. menardii PARKER and JONES, 1865. Phil. Trans., vol. cly, p. 394, pl. xvi, figs. 35-37. Pulvinulina reponda var. menardii subvar pauperata, Id., Ibid., p. 395, pl. xvi, figs. 50, 51. Rotalia paupercula STACHE, 1865. Tert. Merg. Whaingar. Hafen; Novara Reise, geol. Theil, I, 2, p. 277, pl. xxiv, fig. 27. Discorbina saccharina, SCHWAGER, 1866. Novara-Exped., geol. Theil. vol. ii, p. 257, pl. vii, fig. 106. Pulvinulina menardii OWEN, 1867. Journ. Linn. Soc. Lond., vol. ix, Zool., p, 148, pl. v, fig. 16. Rosalina asterites GUMBEL, 1868. Abhandl. d. k. bayer. Akad. Wiss., II, cl. vol. x, p. 658, pl. ii, fig. 101, a-c. Pulvinulina erinacea KARRK., 1868. Mioc. Fauna Kostej; Wien, Sitz-Ber. I, 58, p. 187, pl. v, fig. 6. ?Truncatulina budensis HANTKEN, 1875. Foram. Clav. Szab. Sch., p. 75, pl. viii, fig..6. Pulvinulina menardti var. cultrata VAN DEN BROECK, 1876. Ann. Soc. Belg. Micr., vol. ii, p. 141, pl. iii, figs. 18, 15. Pulvinulina menardti BRADY, 1879. Quart. Journ, Micr. Soc., vol. xix, n. s., p. 80. Pulvinulina menardii GOES, 1882. Kongl. Sven.-Vet. Akad. Handl., vol. xix, p. 112, pl. viii, figs. 289-295. Pulvinulina menardii BRaADy, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 690, pl. ciii, figs. 1, 2. Testa ovali, depressissima, punctata, carinata, cultrata, supra subcomplanata, subtus convexinscula; spira subplana, anfractibus duobus limbatis; loculis sex ovatis, contectis, supra lmbatis. Shell oval, very depressed, punctate, carinate, sickle shaped, above subcom- pianate, below somewhat convex; spire subplanate, with two whorls limbate ; foramina six, ovate, context, above limbate. Locality. Saline county, Nebraska. NUMMULINID&. Sub-Family NUMMULITIN 4. OPERCULINA, dOrbigny. OPERCULINA comPLANATA Defrance, sp. PLATE E, FIGS. 5, 37, 39. * Operculum minimum,” PLANCUS, 1739. Conch. Min., p. 18, pl. iii, fig. 1, A, B, C. Lenticulites complanata DEFRANCE, 1822. Dict. Sci. Nat., vol. xxv, p. 453. Lenticulites complanata RASTEROT, 1825. Mem. Geol. Env. Bordeaux, pt. i, p. 18. Operculina complanata d’ORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 281, pl. xiv, figs. 7-10, Modéle No. 80. Operculina ammonea LEYMERTE, 1846. Mem. Soc. Geol, France, ser. 2, vol. i, p. 359, pl. xiii, fig. 11, a, b. 46 THE PALEONTOLOGY OF MINNESOTA. (Operculina. Operculina complanata RUTIMEYER, 1850. Schweizer Nummuliten-terrain, p. 108, pl. iv, fig. 56. Operculina arabica CARTER, 1853. Journ. Bombay Br. R. Asiatic Soc., vol. iv, p. 437, pl. xviii. Operculina hardiei d’ ARCHAIC and HAImMEB, 1853. Descr. Anim. Foss., du groupe nummulitique d l’Inde, p. 346, pl. xxxv, fig. 6, a, b, c. Operculina complanata PARKER and JONES, 1861. Ann. and Mag. Nat. Hist., ser. 3, vol. viii, p. 229. Operculina studeri KAUFMANN, 1867, Geol. Beschreib. des Pilatus, p. 151, pl. ix, figs. 1, 2. Operculina marginata, Id., Ibid., p. 152, pl. ix, fig. 4. Operculina complanata SCHWAGER, 1877. Boll. R. com. Geol. D’Ital., p. 17, pl. fig. 22. Operculina complanata MoEstus, 1880. Foram. von Mauritius, p. 104. Operculina complanata BRADY, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 743, pl. exii, figs. 3, 4, 5, 8. Operculina complanata WOODWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. and Nat. Hist. Surv. Minn., p. 175, pl. iv, fig. 35. Lenticulites planulata Lamx., Ann. du Mus. d’Hist. Nat. “Coquille lenticulaire, lisse et ressemblant a une petite nummulite a centre un peu convexe des deux cotés, a cloisons courbes et bombées dans le sens de l’accroissement de la coquille: elle est lisse, et l’on voit extérieurement la forme des cloisons. Largeur, deux lignes ; épaisseur une demi-ligne.” L. planulata. Shell lenticular, smooth and resembling a little nummulite, with centre somewhat convex on both sides, partitions curved, swelled in the direction of growth of the shell, smooth, and the form of the partitions can be seen on the exterior. Width 2 lines, thickness 4 line. L. complanata Drr. “Cette espece a beaucoup de rapports avec la précédente : mais il est aisé de la distinguer par son grand aplatissement. On l’a trouvée a Anvers, prés de Pontoise, a Dax, a Loignan pres de Bordeaux, a Boutonnet pres de Montpellier, et en Italie dans les couches qui paroissent appartenir au calcaire coquillier grossier.” L. complanata Der. This species very much resembles the preceding, but is easily distinguished by its great flatness. Found at Antwerp near Pontoise, Dax, Loignan near Bordeaux, Boutonnet near Montpellier, and in Italy in the Ualeaire grossier beds (which appear to belong to the Middle Kocene). Locality. Meeker county and northeastern Minnesota; South Chicago, Illinois. OPERCULINA COMPLANATA Var. GRANULOSA Leymerie. PLATE E, FIG. 38. Amphistegina fleuriausi VORBIGNY, 1826. Ann. Sci. Nat., vol. vii, p. 304, No. 7 (name only), fide Reuss. Operculina granulosa, LEYMERIE, 1846. Mem. Soc. Geol, France, ser. 2, vol. i, p. 359, pl. xiii, fig. 12, a, b. Amphistegina fleuriausi REUSS, 1861. Sitzungsb. d. k. Ak. Wiss. Wien, vol. xliv, p. 308, pl. i, figs. 10, 12. Operculina irregularis Reuss, 1864. Denkschr. d. k. Acad. Wiss. Wien, vol. xxiii, p. 10, pl. i. figs. 17, 18. Operculina granulata GéMBEL, 1868. Abhandl. d. k. bayer. Akad. d. Wiss., II, cl. vol. x, p. 663, pl. ii, feel) asp: Operculina var. granulosa BRADY 1864. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 743, pl. exii, figs. 6, 7, 9, 10. Operculina complanata var. granulosa WOODWARD and THOMAS, 1885. Thirteenth Annual Report, Geol. and Nat. Hist. Surv. Minn., p. 175, pl. iv, fig. 36. CRETACEOUS FORAMINIFERA. 47 Operculina complanata var. granulosa.] Operculina granulosa. B, 12, a, b, c. “Cette petite operculine, que l’on trouve dans les mémes gisements que la précédente, nous parait devoir en étre séparée. Elle est constamment plus petite ; ses cloisons, quise montrent enformant un léger relief la surface du tesf infiniment mince qui renferme les spires, sont ici proportion- nellement plus serrées. Cette espéce trés plate se compose de 3 a 4 tours de spire. Elle porte a sa surface, de chaque coté, un certain nombre de fines granulations qui se trouvent irréguliérement distribuées sur les petites cotes en relief qui correspond- ent aux cloisons interieures. Ces points saillants, rares sur les derniers tours, se trouvent agglomérés au centre chez beaucoup d’individus. Diamétre, 4 a 5 millim.” Operculina granulosa. B, 12 a,b, ec. This little Operculina, which is found in the same layers as the preceding (0. ammonea), appears to us worthy of separation. It is uniformly smaller ; its partitions, which form a slight relief upon the surface of the very thin shell which encloses the whorls, are proportionally more approximate. This species is very flat, and is made up of 3 or 4 spirals. It carries on its surface on each side, a number of fine granulations, which are found irregularly distributed upon the little elevations which correspond to the interior partitions. These pro- jecting points, scarce upon the last whorls, are found crowded towards the centre in many individuals. Diameter 4 to 5mm. As there seems to be some doubt and diff.rence of opinion in regard to the species and variety, we will give in addition to the above description the generic diagnosis of H. B. Brady. “The test of the typical Operculina is a thin complanate disk, composed of three or four broad convolutions symmetrically arranged and equally visible on both faces. The central portion of the disk is usually somewhat thicker than the outer whorls, and not unfrequently almost umbonate ; the earlier convolutions are more or less embracing, the later whorls evolute. The segments are usually very numerous, of gradually increasing size, and typically very short in the direction of growth, as compared with their width radially; they are for the most part produced on a uniform plan, but near the finish are often irregular, both as to shape and size (PI. exii, figs. 3, 4 and 6, Rept. Foram. Challenger). The exterior is sometimes smooth, but, more frequently, either the sutures or the surface of the chambers, or both, are ornamented with exogenous granules, papillae or tubercles, which, as a rule, are more strongly developed near the centre than on the later whorls ; and in the small northern variety of the genus, the septal lines and periphery are distinctly limbate. The general aperture is a straight or slightly curved fissure at the inner margin of the final segment, close to the periphery of the previous convolution; but the test has frequently also a number of secondary orifices, in the form of small circular 48 THE PALEONTOLOGY OF MINNESOTA. [Nonionina pores on the face of the terminal segment. The septa are double, and the skeleton is furnished with a system of canals the general features of which are analogous to that of Nummulites.” Locality. Meeker county, Minnesota. Specimens of this variety have heen identified in the Eocene at Jackson, Mississippi. Sub-Family 2. POLYSTOMELLIN 4. NONIONINA, d’Orbigny. Nonronina scapHa Fichtel and Moll. Sp. PLATE E, FIGS, 35, 36 Nautilus scapha FICHTEL and MOLL, 1803. Test. Micr., p. 105, pl. xix, figs. d-f. Nonionina sloani VORBIGNY, 1839. Foram. Cuba, p. 68, pl. vi, fig. 18. Nonionina scapha PARKER and JONES, 1860. Ann. and Mag. Nat. Hist., ser. 3, vol. v, p. 102, No. 4. Nonionina boneana Reuss, 1863. Bull. Acad. Roy. Belg., ser. 2, vol. xv, p. 156, pl. iii, figs. 47, 48. Nonionina scapha BRADY, 1865. Nat. Hist. Trans., Northd. and Durham, vol. i, p. 106, pl. xii, figs. 10, a, b. Polystomella crispa var. (Nonionina) scapha PARKER and JONES, 1865. Phil. Trans., vol. clv, p. 404, pl. xiv, figs. 37, 38; pl. xvii, figs. 55, 56. Nonionina scapha BRADY, 1884. Report on Foram., H. M.S. Challenger, Zool., vol. ix, p. 730, pl. cix, figs. 14, 15 and 16? “Testa spiralis involuta subovalis, utrinque wmbilico impresso parvo, lateribus mediocriter convexis (minus quam in precedente Non. faba, sed magis quam in sequente N. crepidula); dorso obtuso; articulis duodecim conspicuis, subelevatis, levibus; dissepimentis antrorsum mediocriter convexis, non omnibus ex centro radiantibus, sed tribus ultimis parum extravagantibus ; plano orali oblongo—sub- cordato convexo ; orificio (in specimine obvio unico partim detrito) prassumtive, uti in aliis similibus, lineari parabolice arcuato.” Shell spiral, involute, suboval, slightly umbilicate on both sides, sides moderately convex (less than in the preceding N. faba, but more than in the following N. crepi- dula), back obtuse ; with twelve conspicuous chambers ; subelevate, smooth ; par- titions moderately convex anteriorly, not all radiating from the centre, the last three a little eccentric ; the plane of aperture oblong, subcordate, convex ; aperture (in specimen figured somewhat worn away) probably as in similar species, linear para- bolic arcuate. The following description will make the above more comprehensible. “The test of Nonionina scapha is of elongate oval contour, and more or less compressed, the peculiar form being due to the rapid increase in size of the later segments. This increase is not merely in the length of the chambers, but also in their thickness. The peripheral edge of the later portion of the test is obtuse or rounded, and the exposed septal face of the final segment varies from oval to more or less cordate.” Brapy, loc. cit. Locality. South Chicago, Illinois. CRETACEOUS COCCOLITHS AND RHABDOLITHS. 49 III. COCCOLITHS and RHABDOLITHS. PLATE E, FIGS. 1, 2. The nearest representative of the typical chalk of England and continental Kurope with which we are familiar, is found where the Cretaceous rocks are exposed along the Upper Missouri and Niobrara rivers. It there forms bold bluffs for many miles, and the name “Chalk” is very properly applied to it, from the fact that, like the chalks of Europe, it is largely composed of Foraminifera and coccoliths, to which, in these formations, is added the more recently discovered rhabdolith. It has long been known that Huropean chalk was largely composed of Foraminifera, but it is only of late years and with improved microscopes that attention has been called to these minute calcareous objects now known as “coccoliths”, and yet more recently that the “rhabdoliths” have been noticed. Ehrenberg first recognized coccoliths associated with Foraminifera, as forming an important constituent of chalk, and called them “morpholites of chalk.” The name by which they are now known was given them by Prof. Huxley in 1858, who found them to be characteristic of many deep-sea sediments. Dr. Wallich called them coccospheres. They have been carefully studied by Sorby, Hackel, Schmidt and many others, but none of them seem to know their true nature or to be able to place them in any appropriate group. Of rhabdoliths, Dr Geo. M. Dawson, in his valuable paper, “ Foraminifera, Cocco- liths and Rhabdoliths from the Cretaceous of Manitoba” (Canadian Naturalist, April, 1574), writes as follows: “Rhabdoliths were first discovered by Dr. 0. Schmidt in 1872 (Ann. and Mag. Nat. Hist., 1872), in the Adriatic sea, in association with cocco- liths, with which they appear to be closely allied in structure and mode of increase. I do not know that they have heretofore been found in the fossil state. In samples of Cretaceous limestone from Manitoba and Nebraska both coccoliths and rhabdo- liths are abundant, and constitute indeed a considerable proportion of the substance of the rock. The rhabdoliths agree closely with those figured by Dr. Schmidt, and pass through nearly the same set of forms as those there represented. The cocco- liths agree with those figured in the same place exactly, and also with those found in the English chalk and recent seas. They are in a remarkably good state of preservation. The average diameter of the larger among them is about .003 milli- meter, which agrees very nearly with those found in other places. Dr. Giimbel has discovered coccoliths in limestones of many ages, and they appear, though so minute even in comparison with Foraminifera, to have played no unimportant part in the fixation of calcareous matter and the building up of the crust of the earth.” —4 50 THE PALEONTOLOGY OF MINNESOTA. {Radiolaria. Coccoliths and rhabdoliths, associated with Foraminifera, abounded in most of the soft Cretaceous limestone from New Ulm, Minnesota, and some of the chalk rock was mostly composed of them, and was almost entirely free from sand. 1875. 1888. REFERENCES. Husxley, T. H. Deep-sea Soundings in the North Atlantic Ocean, between Ireland and New- foundland, made in H. M.S. Cyclops, Lieutenant Commander Joseph Dayman, in June and July, 1857. Sorby, H. C. On the Organic Origin of the so-called “ Orystalloids” of the Chalk. Ann. and Mag. Nat. Hist.. ser. 3, viii, pp. 193—200, wood cuts. Wallich, G. C. Remarks on some novel Phases of Organic Life, and on the Boring Powers of minute Annelids, at great Depths in the Sea. Ann. and Mag. Nat. Hist., ser. 3, viii, pp. 52-58, 3 wood cuts. Wallich, G. C. Further Observations on some novel Phases of Organic Life at great Depths in the Sea. Ann. and Mag. Nat. Hist., ser. 3, ix, pp. 30, 31. Wallich, G. C. Further Observations on Amoeba villosa and other indigenous Rhizopods. Ann. and Mag. Nat. Hist., ser. 3, xi, p. 445. Hualey, T. H. On some Organisms living at Great Depths in the North Atlantic Ocean. Quart. Journ. Mic. Soc., 1868, pp. 203-212. Thomson, W. On the Depths of the Sea. Ann. and Mag. Nat. Hist., ser. 4, iv, pp. 112-124. Gimbel, OC. W. Vorlaufige Mittheilungen uber Tiefseeschlamm. Neues Jahrbuch fur Min., 1870, pp. 753-767. Schmidt, O. Uber Coccolithen und Rhabdolithen. Sitzungsb. der kais. Akad. d. W. math. naturw. Ixii, Bd. Abth. 1of I, I. Schmidt,O. On Coccoliths and Rhabdoliths. Ann. and Mag. Nat. Hist., ser. 4, x, pp. 359-370, pls. xvi, xvii. Translation by W. S. Dallas, F. L. S. Gimbel, OC. W. Coccolithen im Eocanmergel, fehlen dem Tiefseeschlamm der bayerischen Alpen; Untersuchung dichter Kalksteine; Arten der Oolith-Bildung. Neues Jahrbuch fur Min , 1873, pp. 299-304. Thomson, C. W. The Depths of the Sea, pp. 412-415, figs. 63, 64. Dawson, G. M. Note on the Occurrence of Foraminifera, Coccoliths, etc., in the Cretaceous Rocks of Manitoba. Can. Nat., vii, pp. 252-257. Dawson, G. M. Report on the Geology and Resources of the region in the vicinity of the Forty-ninth Parallel, from the Lake of the Woods to the Rocky Mountains, p. 80. Cretaceous and Tertiary Rocks of the vicinity of the Forty-ninth Parallel—Pembina Escarp- ment to Wood Mountain, in which he says the finer part of the softer portions of the rock is composed almost entirely of the extremely minute bodies which are included under the general name, Coccoliths and Rhabdoliths. These are now known to belong to minute pelagic vegetable organisms. Wallich, G.C. On the true nature of the so-called ‘‘ Bathybius,” and its alleged function in the Nutrition of the Protozoa. Ann. and Mag. Nat. Hist., pp. 122-339. Agassiz, A. Three Cruises of the Blake, I. Bull. Mus. Comp. Zool. xiv, p. 209. IV. RADIOLARIA, Ere. Rapronaria, Muller. PLATE E, FIGS. 3-9. An order of Rhizopoda which possess a siliceous test, or siliceous spicules, a central capsule, and peculiar yellow or brownish-yellow cells. Among the Radio- laria are great numbers of minute and beautiful organisms when living, and in some formations in their fossil state. They are widely diffused, and have been discovered in nearly every ocean and sea. Ehrenberg found them at Cuxhaven and in dredg- CRETACEOUS RADIOLARIA. 51 Porifera.] e ings from the Antarctic seas. Bailey describes them from the Atlantic, Muller from the Mediterranean, Hiieckel from the Adriatic, Wallich from the Indian ocean, and Carpenter and others from deep-sea soundings of the North Atlantic. The siliceous shells of the Polycystinw (one of the families of the Radiolaria to which most of our specimens belong) accumulated in thick deposits during the latest geo- logical periods, and myriads of their exquisite microscopical forms are found in many of the strata of Sicily, Greece, Bermuda, Barbadoes, New Zealand, California, and Virginia, and are now noted in the Cretaceous of Minnesota, Nebraska and Illinois. While somewhat abundant in some of the material, which yielded a few good specimens, they were mostly so fragmentary that we will not attempt to describe or identify them, but have figured a few specimens. They occurred most abundantly in the Nebraska clay, but the best preserved forms were from a soft dark-brown shale from near Rainy lake, northeastern Minnesota, and a few fairly preserved specimens were secured from Calumet (Illinois) clay. © PoRIFERA. “ PLATE KE, FIGS. 17-29. . Sponge spicules, mostly fragmentary, were quite frequent in some of the samples of material from Minnesota and Nebraska, but the spiculation of the sponge varies so greatly in the same species and even in the same collection, that we will not venture to place them, but have figured a few specimens on plate HE, figs. 17-29, of which 24-27 are probably of fresh water and the others of marine origin, EcHINODERMATA. PLATE E, FIGS. 30-32. Many fragments of spines or plates, probably of Echinodermata, well known marine animals, were found in some of the specimens of clay from Nebraska, specimens of which we have figured in plate H, figs. 30-82. MiscELLANEOUS. The well-defined organisms shown on plate E, figs. 10-16, we do not recognize. Fig. 15 is apparently a fish’s tooth. In the Chicago clay there are some very curious arenaceous cases, looking as if at some time they had covered very minute rootlets, or other organisms, which had decomposed, leaving these cases, which closely resemble rhizocarps of the genus Aschemonella, as figured by H. B. Brady. 52 THE PALEONTOLOGY OF MINNESOTA. {Table of Distribuuleren ‘LIST OF THE MICROSCOPIC ORGANISMS FOUND IN THE CRETACEOUS FROM MINNESOTA, NEBRASKA AND ILLINOIS, SHOWING THEIR DISTRIBUTION. -” Au i= u <~ ‘ & fase] = & a js) oe. a bed | i] = Sa Maine ict a. x) ih SOUS POS Satie ts 9AM FORAMINIFERA. ms mao g Su Ou bse on ®o 5 D) Fs cs iS P Be) o o <~g a8 05 92 Bs fo) $5 | 2583] se eis B32 = rd era ae ze Trochammina inflata Montagu, sp...................- 2 | * Textularia agglutinans d’Orbigny .........,........ = % * * ee Carinatagd Oxley tecriee cee % te globulosalMhrenbengeemciericcilertiecieciieiteies | m8 i * * turrisec@Orbicnyeeeeneeeeccetceacreaae. es * m3 Spiroplecta americana Ehrenberg a ud ce Gaudryina pupoides d’Orbigny.,...................-- 8 * % Verneuilina pygmea Wegger, sp...........-.--2----ee as * Buliminajafinis a’ Orbignye -secscceoweeeaeeecee cele * ee PUpoldesw GiOrbignys asset eke eee * * * Pleurostomella subnodosa Reuss ...............+ee08- * * Bolivin‘aidilatatay Reussei. ence cee eeeeecicere. a My punctabamc@Oxrbignynaerceceeeree ceoeeeac * * * agpenavaspera WRGUSS sce jean cick oc cro ccmeocie ieee tcleletsision * S$" HISpida FREUSS! se... 2.2.0s/ 3; - es il At OPI Rt on) rea! Sina 2 PLATE D. PAGE. Higeh Sis TuAGMN AVA PIO AWRGUGS.o) INIT AS Katee stcrctee aster cera le icra utncaieis ovaiers tare oah LTC ns atone Pmt Tekere nae 35 Big 2): GAGE NASBIS EID AWEREU SS arayoseetire are estas cre cee Sel eats oes ae trcist anos al ref elas Gao Seren oe 35 INEHIBI MOVE DANE sO SUN IMACS OPEN COM MAW NIB) E\Olireag7endn dadeachd sbbanennoodaecncnohoasconqacocsande: 36 Migs. ands. sNoDOsSARTATCOMMUNIS @Orbigny. Nebraskas sco. cncecmneccasee eee sees sie eel 36 Wigs 958 MUV IGE RENAUCAN ARTE Namen Oy. OGII DMs esa lsaiieierrrcns e/a sare mio yan cee iat eee hae oe teers 39 Bigs LO UivrGERINA GASP MERU TsO Z| ZOK: SING DTASKAl ss oe. s sere ce ere oe cmetieatleme oc eiee erie eee 39 Migs 1GhoMa"G ROBIGE RIN AGE OL HOID ES (iOrpigny..ce-eetiec ae nee ce saeco niece rmeaeee 40 13 to 17. Specimens from Nebraska. Hiss alsiand=19% CG LOBIGERINAGG RETA OHA G2ORDI GM Y/ccarauieeictsis eeterers sieteeie cet ieeeiiel ial else 41 Figs. 20 and 21. GLOBIGERINA MARGINATA Reuss................-00- Oars GRNTAD Olea aioe sete 42 Wigs) 22,.1G LOBIGHRINAISACCULIMER AB ra Ulver gsea cis aioe aceon Cee eee inte aera 42 Figs. 23 to 27. ARBULINA UNIVERSA @’Orbigny................cseeeecsecuee SActetaietelsjes @ sles arene eiats zertee 43 Figs. 28 and 29. ANOMALINA AMMONOIDES Reuss....... ......-.+- DoedaosseocooRcUsN OA dns oesaae 44 Mig380! VAN OMALINACAMMONOLDEISK(SDsG)WRGUSS camera. nccten ricci cele oleh nn ree eaters tie toc tarme teers 44 igs ole) ROC HAMMIUN AMEN ADAM OT ba Oty S D opeeelofereerskeyerei> crv oom eh chete ceteea tere ie sicions ee terete ieee ue iets erence 28 Del DWT Lith FOU THe HENDERSON -ACHERT-KRERS LiTH. Co. CNCINNAn. Fig. 1. COCCOLITHS... Fig. 2. RHABDOLITHS Figs. 3 to5. RADIOLAR Figs. 10 to 14, 16. Undetermined Fig. 15. Fragment of tooth of fish Fig. 33. PULVINULINA PLATE. E. PAGE. Perey Dee eva A ATEN SYST aV day okelarelnietetatstoie te okelsreholevs cvardvesetelaeleteversYorstoreLercieastemetateKsveratenctetetetererreiacte 49 Saeco nonin cone UbnnO GoD OtoE oftcnsenodasoUddnnd cauTonoobanmdonahoannaeaenao none 49 TAC MANN esotacand Ml llin Oi Steves ncmcue che apecses th eeutain ohaetelcio asic ora ieeiersrete 50 Figs. 6 to 9. RADIOLARIA. Minnesota and Nebraska. ........-.-..0-+e+se cscs cece eee eee ee cence ee 50 RAR An Uh ENE Ra eRe GR Pochh sara nd Homo oEa ADO mae aoe CSUS 51 CPs MMM SC Ett acd Un Sg See ct ane, Re So RARE meee eS ae Re 51 Figs. 17 to 22. Sponge spicules. Nebraska. ...........-..22 25 s0e 2 cee ceee eee ee tec eee e eter eee 51 Figs. 23 to 29. Sponge spicules. Minnesota .....-. ...-..: 00s ee seee eee eee cee terete ee cece ee eee es 51 Figs. 30 to 32. SparaNneus (Echinodermata) spicules. Nebraska........-... 22. .... sees sees eee 51 MENARDII @’Orbigny. Nebraska. Inferior aspect.........................- 45 Fig. 34. PuLVINULINA HAUERI d’Orbigny. Minmesota............20.-- 002s cece ee ee cece tee ete e ee 44 Figs. 35 and 36. NONIONINA SCAPHA Fichtel and Moll, sp. Calumet, TMWinOis: jeenincesn doesn cs 48 Figs. 37 tc 389. OPERCULINA COMPLANATA Defrance..........-. 5s. sees e cette ee tees eee e nee ne nees 45 Fig. 38. OPERCULINA COMPLANATA, Var. GRANULOSA Leymerie GBI Hoa WEY, EPSP, SEU CE CN SP EN, E.0.U. del.et Eith MACBRAIR LitH. Co. Cin.0. ia eral [oie 3 Tai (shal eae peas Verne eo a re pe RES eel toe il 2. ‘Oe 4. Figs. 5and 6. Figs. 7 to 10. tte 8. 9 and 10. Figs. 11 and 12. INANE 12. Figs. 13 to 15. 13. 14. 15. Figs. 16 to 18. 16. 17 and 18. Figs. 19 and 20. 19. 20. Figs. 21 to 23. 22 and 23. PLATE F. Fool WNOL OH Gso Oy Awcel ISNILS Gaboooeasdons. conn sceoan ponddoo on aachaoros0soq0008 The upper or inner surface of a large fragment. Mineola, Minnesota. A portion of the under surface of a specimen in which the head plates are sur- mounted by a knob-like projection. Twelve miles south of Cannon Falls, Minn. A small portion of a large specimen in which are shown twelve radiating canals in each depression left by the spicular head plates. Another portion of the same specimen in which the casts of the radiating canals are removed, leaving the clay fillings between the head plates serrated. Galena shales near Fountain, Minn. Minnesota Geological Survey collection. TSCHADILES LOW NSISh OW EU SIS Diets cays rererer (el ametstetoretedala)atel-tereleretelictalerelalebatetelereteteieaetelstoters View of the under surface and profile of the same specimen, a natural cast of the * spaces left between the vertical rays of the spicules. Galena, Wasioja, Dodge county, Minn. Minnesota Geological Survey collection. TSCGHADUDHS KGENEGHT VIC M1 SOM rteretoretercie!elatolelafaleicteperete ters areloleleteeietatatst=ieietttetetsveleteneieiereiars “The base of Ischadites keenigii Murchison, enlarged three times, showing the eight diamond-shaped spicular plates of the nucleus and the plates succeeding them, each having a clearly marked central spot, indicating the center of the spicule.” (After Hinde.) ‘‘ A portion of the lateral surface of a specimen, enlarged four times, showing the extension of one of the horizontal rays of each spicule, from beneath the distal angle of the correspoding-summit plate, over the summit plate of the spicule in front of it. In the center of the figure are the modified summit- plates developed at the intercalation of a fresh row of spicules.” (After Hinde.) ‘Portion of the lateral areas of two specimens, in which the surface summit- pilates bave disappeared, showing the four horizontal rays of independent spicules. The rays are often incomplete, and they frequently overlap each other. Enlarged three times.” (After Hinde.) HEPIDOLULES DIORA DI: WUTC scare erate eystaiel ote ei aisielsverele lols nlevevoinieiorereeiararetsieleleebaie aetelets Surface of a specimen 10, showing the imbricating character of the head plates. View of the inner side of the integument of another specimen, x 10. Lower part of the Cincinnati group, Covington, Ky. Collection of E. O. Ulrich. ANOMATOSPONGIAGREDICUIAIA (Mliri Chita eeraieleialeinie let ioriels/ereivtelsteieieieieieteieisisielertrielster= A compressed-conical fragment of the natural size. Surface of a well preserved fragment x 18, showing the character and arrange- ment of the spicules. Diagrammatic view of one of the spicules x 18. Cincinnati group, Covington, Ky. Collection of E. O. Ulrich. LRVALOIAN OIG Cy WI AOU Oh Masa rnoraooonmanooscce odoannuoaasdaodouobs doccnacacmoD0Nns View of an average specimen of the natural size. Small parts of the surface of two specimens x 4, showing variable appearance of the spicular network. Middle third of the Trenton shales, St. Paul, and Min- neapolis. Collection of E. O. Ulrich. UATE CAs ACE MITETES I UIT Ch avetatateratarenerapetevete ciayioln sie ressuercieler-rletenstmeetstetchtalieveretare)/aleysccielaiete Small specimen with the radial leaves mostly broken away; natural size. Mid- dle third 01 the Trenton shales, Minneapolis. Geological Survey collection. Surface (x 9) of a well preserved specimen in the collection of E. O. Ulrich. Shows the hirsute appearance of the external spicule layer. SOLENOPERAy COMPACTAS Bilin SStrercemteec -tieeticieteteristeiectetrtekcieereReeieicintstateiatstarsietete A figure of asmall mass. Trenton shales near Cannon Falls, Minn. Minnesota Geological Survey collection. A longitudinal and transverse section x about 50. (After Nicholson.) *The drawings for figures 11 to 20 are by Mr. Ulrich. 64 61 76 80 Plate F. im f i iz = eh a ao Be \ af el io) gs Mines a © ) W ima} on les ed Si (Sr Ales 74 —~ 4 eS) VOLE. pe Te pen (00: ee % Mcoky ‘Bee fr wile Ms Habsery ¢ Hit t0 4s 4 ‘ a tome penny oer ay a * oes ee atau ‘> - Abide Taal Fao Sita viii sia ail aeaioD a 4 ae onli 2 boi 9 ‘al a oyilt ‘was y ee «. agaliut 47 Oe EP pie igwoni? & 1} Aw =n eit ileeqen 2d ¥/ eet AoHrag B ik, nade Figs. Figs. Figs. Figs. Figs. Figs. Figs. Figs. Figs Figs 1 2 and 22 and . 24 and . 26 to 14 to 17 to to 2 10 to 13. 10. 10. 13. 16. 18. 19% 20 and 21. Siow bo ie) bw oO -~I a PLATE .G. CXYEINDROCGIL TAS MENNESOTENSIG# WilL CIR sp oiota here ley= le latel=lel= ole] ole (eio!eta!s\e]olelsie/elsialielelelejeiatar= A small specimen, covered in part by a bryozoan; natural size. Also end view of same, showing numerous unequal canals. A large fragment having canals of unusual size; and an end view of the same; natural size. Upper part of the middle third of the Trenton shales, St. Paul, Minn. Collection of KE. O. Ulrich. Hin TEROSPONGTAGCSUB HAMOS At IPL }iayetetslosoiofeiatelsiotelelelolcvere level ofevatel elotelerslelelelat=toretelal-yalalelai= A fragment of the natural size, doubtfully referred to this species. Hudson River group, Spring Valley, Minn. Collection of E. O. Ulrich. Vertical and tangential sections, x 10, of a typical specimen from Cincinnati, O. HINDIA PAR VA WIriCh i... (1-1 == ApSpuOOoOO oS Doode so saondECn UntAaucHDoAoIroee os Three specimens of this species, showing extremes in size so far observed. Vertical and tangential sections x 10. Upper third of the Trenton shales and Galena shales, Goodhue and Fillmore counties, Minn. Collection of E. O. Ulrich. TCH EN ARAM IS YaPAn to CIE bspSP MEL OV je slelerteleleletelatelotarenstelatete olatelelarfelatatevelotst-(ociststetatetealslete A large colony of this species growing upon a fragment of Callopora incontroversa Ulrich, x 2. A small colony in which one of the buds has grown in a manner suggesting Aulopora, x 5. A longitudinal section through a large colony. Trenton shales, Minneapolis, Minn. University of Minnesota collection. A small free mass of this species, of the natural size, and a portion of the same x 3. The latter shows at a, and in the space to the right, a pore passing from the parent tube into the base of the buds. This fact is important in this that it indicates a relationship of Lichenaria with the Auloporide, rather than with Columnaria, where we have placed the genus provisionally. Middle third of the Trenton shales, St. Paul, Minn. Collection of E. O. Ulrich. CODUDINARTAG (2) pea Te ING CHOISOM eisrelalelaletes Ielatelelereloistele re ele[areielslaletelsialeleleieioioiaslstetetisielere A portion of the surface, to show the septal ridges. Trenton shales, St. Charles, Minn. Minnesota Geological Survey collection. Part of a vertical section, enlarged five times, showing the tabule. (After Nicholson.) Part of a transverse section, showing the amalgamation of the walls of the coral- lites and the marginal septa. (After Nicholson.) STREPTELASMA PRON UIND UM O Wem sacle yotecrelsietatetari=ttetotalnetatats aretetellelsinicrevorcietsteletelsisieie View of a natural cast of the visceral cavity, the usual mode of occurrence in the Trenton limestone, Minneapolis, Minn. An entire specimen in which a portion has been broken away to show the great depth of the body cavity. View of the visceral cavity, showing the three fossule and the counter septum. Base of the Upper Buff limestone, Mineral Point, Wisconsin. Minnesota Geo- logical Survey collection. SPRL ET ASMA UC ORIN TC sla OMe AEM ate saverale er s/aic/e\cierstorerebeteteleveleteieteloiatevcievctectsievstisvee\cla/elaieiere An exterior view of a specimen broken so as to show the depth of the visceral cavity. View of the visceral cavity to show the twisted nature of the septa. Galena shales, St. Paul, Minn. Minnesota Geological Survey collection. SRRERTEDASMAG RUSTIC UM STI M O'S i eversrelepetetereictetetsieletateiereremicretere/clelolerersvele ste doopoocG Rieieis The exterior of an imperfect specimen. View of the visceral cavity, Showing a distinct pseudocolumella. Hudson River group, Granger, Minn. Minnesota Geological Survey collection. PRODTAR:AA VEETUSTA ally Species + . = We ; i CEA THE It. SPONGES, GRAPTOLITES AND CORALS FROM THE LOWER SILURIAN OF MINNESOTA. BY N. H. WINCHELL AND C. SCHUCHERT. Sub-kingdom PORIFERA. Order HEX ACTINELLID 4, Schmidt. Sub-order LYSSAKINA, Zittel. Family RECEPTACULITIDA, Roemer.* Dr. Hinde advances the theory that the sixth or summit ray of ordinary hex- actinellid sponges has in the Receptaculitide been modified so as to form character- istic head-plates. He says (Joc. cit., p. 830), “In no other hexactinellid sponge, so far as I am aware, are there any spicules with similarly constituted head-plates ; in many, however, no sixth or summit ray is developed, but in some of the abnormal spicules of the Carboniferous sponge, Hyalostelia smithiiy Young and Young, sp.. the sixth ray is in the form of a rounded knob. We have only to consider that the sixth ray in the spicules of the Receptaculitide, instead of heing contracted to a knob merely, as in the Carboniferous sponge, has been developed in a horizontal direction, and by additions to its margins, has assumed the regular rhomboidal or hexagonal *The above systematic position of the Receptaculitidw is that of Dr. George Jennings Hinde. Students desiring to learn more of the detailed structure of these species and their affinities to other hexactinellid sponges are referred to Dr. Hinde’s admirable monograph “On the Structure and Affinities of the Family of the Receptaculitida, including therein the Genera Ischadites, Murchison (Tetragonis, Eichwald); Sphzrospongia, Pengelly ; Acanthoconia, gen. nov., and Receptaculites, Defrance,”’ Quar. Jour. Geol. Soc. London, Vol. XL, pp. 795-848. In Nicholson and Lydekker’s ‘* Manual of Palwontology ’’, Appendix to Vol. IL, p. 1563, we learn that the Receptaculitide have recently formed the subject of an important investigation by Herr Rauft (Zeitschr. d. deutschen geol. Gesellschaft, bd.xl). This contribution we are unable to consult. Since, however, Herr Rautf has concluded that * the Receptaculitidw are not siliceous organisms. but that the skeleton was originally caleareous, and the siliceous examples are the result of sili- fication,” Dr. Nicholson is of the opinion that the family “cannot be referred to the Hexactinellid Sponges,” and that “its systematic position is still entirely uncertain.” +See Cat. Foss. Sponges, British Museum, pl. 32, fig. 1. [55] 56 THE PALEONTOLOGY OF MINNESOTA. ([Receptaculites. figure by which it is adapted to fit in with the adjoining spicular plates to form an exterior layer to the organism. Strong confirmatory evidence of the theory that the summit plates of the spicules are modifications of the sixth ray in the ordinary hexactinellid spicule, is afforded by the small blunted knob which projects in the center of these summit plates in the best preserved examples of Sphwrospongia, and traces of which are also present in Acanthoconia. In these forms we find the commencement of the sixth or summit ray in the small central knob, from which, as a centre, the plate is developed horizontally by successive marginal additions.” A new species of Receptaculites, seen in the collection of Mr. E. 0. Ulrich, from the Lower Silurian near Knoxville, Tennessee, has the vertical ray of the spicules with two constrictions, one immediately below the head-plates, and the other near the center of their length. RECEPTACULITES, Defrance. PLATE F, FIGS. 1-4. 1827. Receptaculites, DEFRANCE. Dictionnaire des Sciences Naturelles, t. 45, p. 5, atlas, pl. 68. 1859, Receptaculites, SALTER. Canadian Organic Remains, dec. i, p. 43. 1860. Receptaculites, EicHwALD. Lethwa Rossica, p. 427. 1863. Receptaculites, HALL. Sixteenth Rep. N. Y. State Cab. Nat. Hist., p. 68. 1865. Receptaculites, (partim) BrLLiNes. Paleozoic Fossils, vol. i, p. 378. 1865. Receptaculites, (partim) Bintines. Canadian Naturalist and Geologist, sec. ser., vol. ii, p. 184. 1868. Receptaculites, DAMES. Zeitschr. der deutschen geol. Gesellschaft, bd. xx, p. 483. 1875. Receptaculites, GimBEL. Abhandl. der k. bayer. Akad. der Wissensch. bd. xii, p. 170. 1876. Receptaculites, Z1vrEL. Handbuch der Palwontologie, pp. 83, 727. 1880. Receptaculites, RomER. Letheea Palwozoica, p. 285. 1884. Receptaculites, HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 821. 1885. Receptaculites, JAMES. Jour. Cincinnati Soc. Nat. Hist. vol. viii, p. 163. 1889. Receptaculites, NICHOLSON. Manual of Paleontology, vol. i, p. 170, figs. 6la-61d ; vol. ii, p. 1563. 1891. Receptaculites, JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 60. Description—* Cup or platter shaped bodies of considerable size, with ‘walls of definitely arranged spicules. The outer surface is formed by the rhomboidal head- plates of the spicules; beneath these are the horizontal rays and robust subeylin- drieal vertical rays, which are connected with an inner layer or perforated plate. Communication with the exterior was carried on between the margins of the sum- mit-plates of the spicules on the outer surface, and through the cylindrical canals of the inner surface layer, or, according to Giimbel, through intermarginal canals.” (Hinde, /oc. cit.) According to Nicholson, Rauff concludes that “the Receptaculitide are spherical or pyriform bodies, with a central closed cavity, the supposed basin-shaped examples being only fragments of the base.” Receptaculites oweni Hall, is a platter-shaped species attaining a great diameter ; is widely distributed, and of common occur- rence in the Galena formation throughout the Northwest. In Minnesota, the SPONGES, GRAPTOLITES, CORALS. 57 Receptaculites oweni.] diameter of this species is from four to twelve inches, and nearly every specimen obtained preserves the nucleus, Fragments are rare, but when secured prove to be portions not far removed from the nucleus. If &. oweni were originally a spherical or pyriform body, we should expect to find fragments of the upper portion, and these could be readily determined by the impression left by the head-plates. Such parts have not been discovered in the Northwest. Further, it is stated that “the genus /schadites agrees essentially with Receptaculites in structure, but its skeletal elements are more slender.’ We fail to find an in- ternal integument in Jschadites, or the lateral extension of the vertical rays in the “oastral” cavity ; they have been observed as terminating freely, and pointed at their extremities, in specimens of Ischadites iowensis, but apparently end bluntly in Lepidolites. It may be that the lateral extension of the vertical rays of the spicules forming the upper integument in R. occidentalis and R. oweni served the same purpose as the large number of plates discovered by Herr Rauff, closing the heretofore sup- posed apical opening in Ischadites, 7. e. for the regulation of the water currents. These lateral extensions of the vertical rays of the upper surface in F. oweni are traversed by from ten to twelve horizontal canals. ReEcEPrACULITES OweENI Hall. PLATE Ff, FIGS. 1-4. 1844. Coscinopora sulcata OWEN (non Goldfuss). Geological Report of lowa, Wisconsin, and Illinois, p. 40, pl. 7, fig. 5. 1861. Receptaculites oweni HALL. Report of the Superintendent of the Geological Survey of Wiscon- sin, p. 13. 1862. Receptaculites oweni HALL. Geological Report of Wisconsin, p. 46, fig. 2, and p. 429. i868. Receptaculites owenti MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 302, pl. 2, fig. 3. 1882. Keceptaculites owent WHITFIELD. Geology of Wisconsin, vol. iv, p. 239, pl. 10, fig. 7. 1883. Receptaculites owenti HALL. Twelfth Rep. State Geologist of Indiana, p. 243, pl. 1, fig. 1. 1884. Receptaculites occidentalis (partim) HrNDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 842. Original description —* Body consisting of a broad expanded disc, from four to twelve inches [even twenty inches] in width, and from one quarter to half an inch [sometimes 20 mm.] in thickness (rarely a little thicker). Surface undulating with an abrupt funnel-shaped depression in the center of the upper side | with a small conical projection on the under side], from which the cell rows [head-plates of the spicules] radiate in curved lines. “The thickness in the center is not more than one-eighth of an inch, and at a distance of three or four inches from the center is less than half an inch: cells [ver- tical rays of the spicules] cylindrical in the middle and contracted both above and below [from 1 to 3 mm. in diameter], the walls of the cavities often showing trans- verse striz, which appear like the remains of septa [since these cavities are casts of 58 THE PALEONTOLOGY OF MINNESOTA. (Receptaculites owenl. the outer side of the vertical rays of the spicules they are not septa]. The distance of the cells [circular perforations of the matrix once occupied by the vertical rays of the spicules] from each other is variable, those near the center being closer together, though, in receding from the center, there are at intervals intercalated rows of cells, which take the same direction, and give the cells a closer arrangement towards the margin than in the intermediate space before the intercalation of the additional rows. The apertures {impression of head-plates] both above and below are essen- tially rhomboidal [from 3 to 5 mm. in width|; but in well preserved surfaces there are remains of rays, which, however, are rarely observed ; and I have not seen them on opposite sides of the same specimen.” A small specimen of this species from Goodhue county, Minnesota, has the lower surface preserved as crystalline calcite, while all other portions of the sponge are missing. The outline of the plates cannot be determined, but their arrangement is well indicated by a series of knobs arranged in quincunx. These were regarded at first as having been produced by the wearing away of the softer matrix surrounding the crystalline calcite, usually filling the interior of the vertical rays of the spicules in Minnesota specimens. Upon grinding the specimen transversely to the surface, it was discovered that the vertical rays of the spicules are not present, and that only the lower or outer surface of the sponge is preserved. We therefore conclude that each head-plate in this specimen had originally a central knob similar to those figured by Dr. Hinde in Sphwrospongia tessellata Phillips, sp.* In the latter these knobs are comparatively smaller than in Receptaculites oweni Hall. The upper or inner layer is never preserved entirely in Minnesota specimens of R. oweni, and we shall therefore give Dr. Hinde’s description of this integument as it occurs in R. occidentalis Salter, a closely related species: “The vertical rays in this species of Receptaculites continue cylindrical to near their basal extremities, and then abruptly expand into horizontal plates. These plates have four straight sides, but at each of the corners there is a semicircular or semi-elliptical vertical hollow.+ Each plate appears also to be traversed by four horizontal canals, which radiate from the center, where they_are in connection with the canal of the vertical ray. * * * These plates are intimately united together so as to form a continuous inner or upper layer. The delimitations of the separate plates in this layer are not always preserved ; in many specimens they appear to have been completely oblit- erated, and the layer resembles a continuous plate with numerous cylindrical or elliptical canals which penetrate through it at right angles” (/oc. cet. p. $25). In many specimens from Minnesota, the horizontal canals of the upper or inner layer *Loc. cit. pl. 37, fig. 1b. : * +Herr Raut? states, that these vertical hollows or pores did not originally exist in the “ gastral” wall, but are the result of fossilization (Nicholson “* Manual of Palzontology, vol. ii, p. 1564). SPONGES, GRATOLITES, CORALS. 59 Receptaculites owenl.] x are indicated by furrows left between the casts now filling the original spaces. Between the four principal canals, which seem to have communicated with four circular hollows, one situated at each angle of the rhombic spaces, are two other canals, and these also seem to have had openings in the upper surface. In other words, each plate had originally twelve small semicircular hollows communicating with twelve horizontal canals joining in the center with the vertical ray. Where the filling of the spaces between the canals is not preserved, tubercles can be seen distinetly situated at each angle of the rhombic depressions, with two, and occa- sionally only one pustule between them. Along their edges the plates are separated from adjoining ones by distinct walls. These walls are not a portion of the skeleton, but are foreign matter which has accumulated between the plates, and has more or less disturbed their natural position. This species is known throughout the Northwest as the “sunflower coral,” “lead fossil,” or Receptaculites owent Hall. The specimens from Minnesota are from lime- stone and calcareous mud-stones, and rarely occur as hollow casts, but commonly as impressions of the skeleton. The vertical rays are filled usually with crystalline calcite. Dr. Hinde, in treating of R. occidentalis Salter, and R. oweni Hall, says: “The examples from Illinois and other western states are usually of somewhat greater diameter than those from the same horizon in Canada, but from a comparison of specimens from these different places I am unable to detect any differences which would justify regarding them as distinct species. Their external aspect is, however, strikingly dissimilar owing to their different states of fossilization” (Joc. cit. p. 848). On account of the greater size attained by R. oweni, and the plates of the inner sur- face having twelve canals instead of four, as in R. occidentalis, a central knob on each head-plate of the spicules on the outer surface of the former, should be sufficient to distinguish this species. Formation and locality.—Throughout the Galena of Minnesota, Wisconsin, Iowa and Illinois. Some of the more prominent localities are: six miles south of Cannon Falls, Kenyon, Mineola, Fountain, near Marion, Wasioja, and Stewartsville, Minnesota; Decorah and Dubuque, Iowa; Green Bay, Wisconsin ; Galena and Dixon, Illinois. Collectors.—Miss Cora BE. Goode, W. H. Scofield, and the writers Mus, Reg. Nos. 3375, 4944, 6758, 7251, 7714-7721. SYNOPSIS OF AMERICAN SPECIES OF RECEPTACULITES. k. AROTICUS Etheridge. 1878. Receptaculites arcticus EYMERIDGE. Quart. Jour. Geol. Soc. London, vol. xxiv, p. 576. 1882. Keceptaculites arcticus JONES. Catalogue Foss. Foram. British Museum, p.°3. 1884. Receptaculites arcticus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 845. Formation and locality.—Lower Silurian ; Cape Louis Napoleon and Cape Frazer, Arctic regions. 60 THE PALEONTOLOGY OF MINNESOTA. (Synopsis of Receptaculites. R. CALCIFERUS Billings. 1865. Receptaculites calciferus BiLLINGSs. Paleozoic Fossils, vol. i, p. 359, fig. 346; p. 384, fig. 358. 1865. -Receptaculites calciferus BILLINGS. Canadian Naturalist and Geologist, sec. ser. vol. ii, p. 190, fig. 6. 1884. Receptaculites calciferus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 845. This is the oldest known species of the genus. Formation and locality.—Calciferous formation ; Mingan islands, Lower St. Lawrence. R. MAMMILLARIS Walcott. 1884. Receptaculites mammillaris WALCOTT. Monograph U.S. Geological Survey, vol. viii, p. 65, pl. ie fies tle e This species is smaller than RA. occidentalis Salter, and has the outer margin elevated, producing a broad, deep depression in the upper portion. Formation and locality.—Upper part of the Pogonip group=Chazy group of New York ; Eureka and White Pine districts, Nevada. R. ELONGATUS Walcott. 1884. Receptaculites elongatus WALCOTT. Monograph U.S. Geological Survey, vol. viii, p. 66. A cylindro-conical species, with a very deep depression on the upper side. The largest head-plates of the spicules are 1 mm. in width by five-sixths of 1 mm. in length. Formation and locality.x—Upper part of the Pogonip group=Chazy group of New York; Eureka district, and in the Pahranagat range, Nevada. R. ELLIPTICUS Walcott. 1884. Receptaculites ellipticus WALCOTT. Monograph U. S. Geological Survey, vol. viii, p. 67, pl. 11, fig. 12. Seems to differ from R. elongatus in having larger spicular head-plates. The curved form and ellip- tical transverse section may be due to accidental causes. Formation and locality.—Upper part of the Pogonip group=Chazy group of New York ; Eureka district, Nevada. R. OCCIDENTALIS Salter. 21847. Receptaculites neptuni HALL’ (non Defrance), Paleontology of New York, vol. i, p. 68, pl. 24, figs. 3a-8d. 21855. Receptaculites neptuni EMMons. American Geology, pt. ii, p. 230, pl. 14, fig. 1. 1859. Receptaculites occidentalis SALTER. Canadian Organic Remains, dec. i, p. 45, pl. 10, figs. 1-7. 1863. Receptaculites occidentalis BILLINGS. Geology of Canada, p. 937. 1865. Jteceptaculites occidentalis BILLINGS. Paleozoic Fossils, vol. i, p. 381, figs. 354-356. 1865. Receptaculites occidentalis BrLLINGs. Canadian Naturalist and Geologist, sec. ser., vol. ii, p. 187, figs. 2-4. 1884. Receptaculites occidentalis HINDE. Quar. Jour. Geol. Soc. London, vol. xl, p. 842, pl. 37, figs. 3a-3m., Very similar to R. oweni, but it differs in having a greater number of canals in the plates of the upper or inner surface; also in the head-plates of the outer or under surface having prominent central knobs. Formation and locality.—Trenton limestone; Pauquette Rapids, Ottawa river, Canada; two miles south of High Bridge, Kentucky; and ? Oarlisle, Pennsylvania. Rk. INFUNDIBULIFORMIS Haton, sp. 1832. Coscinopora infundibuliformis HATON. Geological Text Book. 1863. Receptaculites infundibuliformis HALL. Sixteenth Rep. N. Y. State Cab. Nat. Hist., p. 67. 1883. Receptaculites infundibuliformis HALL. Second Ann. Rep. N. Y. State Geologist, pl. 28, fig. 10. 21883. Receptaculites monticulatus HALL. Ibidem, pl. 23, figs. 3-9, 11. 1887. Receptaculites infundibuliformis HALL. Paleontology of New York, vol. vi, p. 290, pl. 24, figs. 3-11. A large disk-shaped species much like R. occidentalis. The specimens to which the name &. monti- culalus has been given are now regarded by Prof. Hall as the young of this species and should be compared with Cerionites dactylioides Owen, sp.,* of the Niagara group. Formation and Locatlity.—Lower Helderberg group: Helderberg Mts., New York. *Geol. Surv. Illinois, vol. iii, p, 345, pl. 5, figs. 2a-20; 1868. SPONGES, GRAPTOLITES, CORALS. 61 Ischadites.[ R. BURSIFORMIS Hall. 1863. Receptaculites catoni HALL. Sixteenth Rep. N. Y. State Cab. Nat. Hist., pp. 68, 226 (not defined). 1883. Receptaculites bursiformis HALL. Second Ann. Rep. N. Y. State Geologist, pl. 238, figs, 12-14. 1887. Ischadites bursiformis HALL. Paleontology of New York, vol. vi, p. 291, pl. 24, figs. 12-14. Much like R. infundibuliformis in shape, but with larger head-plates of the spicules than in that species. Formation and locality.—Schoharie grit; Albany and Schoharie counties, New York, R.? SAOCCULUS Hall. 1879. Receptaculiles sacculus Hay. Transactions Albany Institute, vol. x. 1882. Receptaculites sacculus HALL. Eleventh Rep. State Geologist of Indiana, p. 222, pl. 1, fig. 5. Probably this fossil does not belong to the Receptaculitide. Its nature cannot be determined from the description and figure given. Formation and Locality.—Niagara group; Waldron, Indiana. R.? INSULARIS Billings. 1866. Receptaculites ?insularis BILLINGS. Catalogue Silurian Foss. Anticosti, p. 29. 1884. Receptaculites ?insuiaris HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 846. ‘* Probably belongs to a quite distinct group” (Hinde). Formation and Locality.—Anticosti group ; Anticosti. R.? ELEGANTULUS Billings. 1865. Receptaculites ? elegantulus BILLINGS Paleozoic Fossils, vol. i, p. 360, fig. 347. 1884. Receptaculites ? elegantulus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 846. This does not belong to the Receptaculitide. _ Formation and Locality —Calciferous formation ; Mingan islands, Lower St. Lawrence. R.? DEVONICUS Whitfield. 1882. Receptaculites devonicus WHITFIELD. Annals New York Acad. Sci., vol. ii, p. 198. 1890. Receptaculites devonicus WHITFIELD. Ibidem, vol. x, p. 519, pl. vi, fig. 10. Probably an Ischadites. Formation and locality —Corniferous of Ohio. ISCHADITES, Murchison emende Hinde. PLATE F, FIGS. 5-10. 1839. Ischadites, MURCHISON. Siluria, p. 697. 1842. Tetragonis, EICHWALD. Urwelt Russlands, hft. ii, p. 81. : 1852. Selenoides, OWEN. Geological Survey of Wisconsin, Iowa, and Minnesota, p. 586. 1859. Dictyocrinus, HALL. Palwontology of New York, vol. iii, p. 135. 1865. Receptaculites, (partim), BrLLINnes. Paleozoic Fossils, vol. i, p. 378. 1884. Ischadites, HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 810. The following description is somewhat condensed from Dr. Hinde’s detailed diagnosis of this genus (Joc. cit. p. 811): “Outer form variable. The prevalent forms are ovate or biconvex; depressed conical; subspherical and pyriform. Base either obtusely conical, flattened or concave. Summit usually obtusely conical; rarely with a small central elevation. A small circular perforation is present in the center of the summit which opens into the originally hollow cavity of the body. [According to Herr Rauff, this opening is closed by a large and variable number of plates.| 62 THE PALEONTOLOGY OF MINNESOTA. {Ischadites “The structure consists of spicules of various dimensions, regularly arranged in vertical and oblique rows, and held in position by the interlocking of their summit- plates and horizontal rays. Head-plates of the spicules delicate structures with smooth, flattened outer surfaces, thickest in the central portion where they connect with the horizontal rays, and gradually diminishing towards the margins, which are very thin. They have a generally rhomboidal outline, but in some parts of the speci- men two of the sides of the rhomboids are not uniformly straight, but have a slight curve, which gives the plates the form of a sector of a circle. Another modification is frequently, if not invariably, present in the spicular-plates of the basal portion, which have their angles, or those directed away from the basal nucleus, either trun- cate or with a slight notch, from which one of the horizontal rays projects and extends nearly to the center of the plate immediately in front. The plates forming the basal nucleus are also more elongated than any others. The plates near the nucleus, as well as those of the nucleus itself, are relatively small, but they quickly increase in size towards the zonal area, where they attain their great- est dimensions (2 to 4 mm.); they then gradually diminish in size towards the summit, and the smallest plates surrounding the summit-aperture are scarcely dis- tinguishable without a lens, measuring from .25 to 4 mm. in width, or about one- tenth of the diameter of the zonal plates. “Head-plates arranged in regular spiral curves which, starting in opposite direc- tions from the basal nucleus and extending to the summit, give to the surface the exact appearance of the engine-turned case of a watch. Kach rhomboidal plate is so arranged that one of its angles points to the basal nucleus, and its opposite angle to the summit of the specimen, whilst the other angles are lateral, so that the distal angle of one plate is in contact with the proximal angle of the plate immediately in front of it. Thus vertical lines extending from the base to summit would pass through the proximal and distal angles of the plates, whilst concentric lines would pass through the lateral angles. At the nucleus, or center of the base, there is a series of eight minute spicules with diamond-shaped head-plates, which are so arranged as to form a star-shaped figure, the distal angles of each plate representing one of the rays of the star, and a line connecting the lateral angles would trace a small circle, with the proximal angles of the plates for its center. “As a rule the margins of the plates appear to fit closely and evenly to each other, but in some eases the upper or front margins seem to be slightly elevated as if they imbricated over the lower or hind margins of the spicular plates immediately in front, and left a small intermediate space now filled with the matrix. That the plates, or at least those of the lower portion of the organism, did not fit so closely as SPONGES, GRAPTOLITES, CORALS. 63 Ischadites.] to exclude the passage of water from the exterior to the interior cavity of the organ- ism, is shown by the fact that one of the horizontal spicular rays projects from under- neath the distant angle of each of the plates and extends over the outer surface of the plate in front, thus clearly preventing a close-fitting union at the margins, and, further, the ridges, which characterize the outer surface of the casts of specimens, are produced by the infilling of the matrix in the interspaces between the margins of the plates. “These summit- or head-plates appear to have been connected by a somewhat narrow neck to the horizontal rays of the spicules at the central point of junction with these and the vertical rays, as the horizontal rays appear to be independent except at their central junction. Asa rule, the head-plates are seldom preserved in situ. “The surface of the fossil immediately beneath the rhomboidal spicular plates is divided into minute oblong rectangular areas by vertical and concentric lines. These lines are formed by the apposition of the horizontal spicular arms or rays. The spicules, in addition to the head-plate, consist of five rays; four extended in a horizontal direction, at right angles to each other, whilst the fifth extends from the junction of the four with the summit-plate towards the interior of the organism, and thus at right angles to the horizontal rays. The spicular rays are circular in trans- verse section, thickest at their central point of junction with each other and the head-plate, and they gradually taper to bluntly-pointed extremities [In Ischadites iowensis they are needle-shaped|. Canals present in the interior of the rays. The vertical or entering ray appears to be the longest, the lateral rays are subequal, whilst the distal ray, or that pointing to the summit of the specimen, seems to be longer than the opposite or proximal ray. “The four horizontal rays are so arranged that each ray extends towards one of the angles of the head-plate of the spicule. Thus one ray, the proximal, points to the basal nucleus, and its opposite, the distal, to the summit. This distal ray in the basal portion of the organism frequently projects beyond the margin of the spicular head, and overlies the head-plate of the spicule immediately in front or above it. “The vertical rays of the spicules, which extend at right angles to the summit- plates and the horizontal rays, are only seen when the interior of the specimens is exposed by fracture or by section. They appear as delicate, gradually tapering shafts, the extremities of which are pointed, and reach about half way to the center of the interior cavity, where they terminate freely. An interior plate or integument corresponding to that in Receptaculites has not been observed. “The genus Ischadites itself has, by several writers, been regarded as identical 64 THE PALEONTOLOGY OF MINNESOTA. [Ischadites iowensis. with Receptaculites, but though similar in its main structural features to this latter genus, it is sufficiently characterized by its conical or ovate form, inclosing a central cavity, with a small summit aperture, and by the absence of an inner layer. From Spherospongia, Pengelly, it is distinguished by the rhomboidal form of the spicular plates, and the development of vertical spicular rays; and from Acanthochonia by its conical ovate form and central cavity.” Dictyocrinus was at first doubtfully placed among the Crinoidea. Later, however Prof. Hall referred the type species to Receptuculites and then to Ischadites. ISCHADITES LOWENSIS Owen, sp. PLATE F, FIGS. 5, 6. 1844. Orbitolites reticulata OWEN. Geological Report, Iowa, Wisconsin, and Illinois, pl. 18, fig. 7. 1852. Selenoides iowensis OWEN. Geological Survey of Wisconsin, Iowa, and Minnesota, p. 587, pl. 2B, fig. 13. 1861. Receptaculites Selenoides iowene HALL. Report of the Superintendent of the Geological Survey of Wisconsin, p. 14. 1861. Receptaculites fungosum HALL. Ibidem, p. 15. 1861. eceptaculites globulure HALL. Ibidem, p. 16. 1865. Receptaculites iowensis BILLINGS. Paleozoic Fossils, vol, i. p. 385, fig. 364. 1865. Receptaculites iowensis BILLINGS. Canadian Naturalist and Geologist, sec. ser., vol. ii, p. 191, fig. 11. ?1868. Receptaculites globularis MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 301, pl. 2, figs. 2a, 2b. 1868. Receptaculites, sp? MEEK and WORTHEN. Ibidem, p. 301, pl. 2, figs. la, 1b. 1884. Ischadites keenigii (partim) HINDE. Quar. Jour. Geol. Soc. London, vol. xl, p. 836. Original description—“One side flatly dome-shaped, the other ring-shaped, enclosing an umbilicus or central depression. Small rhomboidal cells opening on the surface in curved rows, intersecting in arches; the cells gradually increasing in size from the inner margin to the periphery.” (Owen, 1852.) Sponge depressed sub-globose, globose or sub-turbinate ; base more or less con- cave. Greatest width near the base, which varies in diameter from 18 mm. to 70 mm.; hight of the largest and most sub-turbinate form, 35 mm.; the usual size met with is about 50 mm. in diameter, with a hight of 20mm. Summit aperture observed in two examples ; one 9 mm., the other 14 mm. in width. This aperture was prob- ably closed by a number of small plates. Head-plates of the spicules not preserved, Spaces formerly occupied by them arranged in spiral curves starting in opposite directions from the nucleus, and extending to the summit. They enlarge as they recede from the nucleus to the zonal region, thence become narrower and more elongated transversely, closely compacted, and constantly diminishing in size towards the summit. The proximal and distal rays of the horizontal rays are usually absent, while the preserved lateral rays give the surface in the upper portion of the internal cast a distinct series of encircling lines. Near the periphery, traces have been SPONGES, GRAPTOLITES, CORALS. 65 Ischadites,] observed of one of the horizontal rays of a spicule extending beyond the distal angle of its summit-plate over that of the one immediately in front. Vertical rays of spicules subeylindrical, about 15 mm. in length. The above synonomy and Receptaculites ohioensis Hall and Whitfield, FR. sub- turbinatus Hall, and R. jonesi Billings, Dr. Hinde regards as embracing but a single species, Ischadites kenigii Murchison. Rf. ohioensis and R. subturbinatus are from the Niagara group of Ohio and Indiana ; the first differs in the comparatively large head- plates and in its strongly convex base, while the latter has much larger head plates on the sides than Ischadites iowensis. R. jonesi agrees with Ischadites cowensis in form but as it is from a later geological horizon, we prefer to retain the species, partic- ularly since we have no examples for comparison. Ischadites iowensis is constantly more or less strongly concave, never conical, and but rarely flattened on its under side. It attains a larger size and has comparatively smaller head-plates than L. kenigii. Since these features are constant in I. iowensis, we deem it sufficient ground to retain this species as distinct from that form. All the specimens of J. iowensis from Minnesota, seen by the writers, are de- pressed sub-globose, never sub-turbinate. J. fungosus Hall might be recognized as a good variety, were it not that both forms have been found lying with the umbilicated side downwards within a foot of each other, in the side of a cliff at Decorah, Lowa. Formation and locality —Galena formation of Iowa, Wisconsin, and Minnesota, In Minnesota, this species is usually obtained from the lower portion of the Galena; some localities are six and twelve miles south of Cannon Falls in Goodhue county, and Wasioja, Dodge county. Mr. F. W. Sardeson informs the writers that he obtained this species in the Hudson River or Cincinnati group, near Spring Valley, Minnesota. Mus. Reg. Nos. 5839, 6760, 7250. SYNOPSIS OF AMERICAN SPECIES OF ISCHADITES. I. CYATHIFORMIS Hall. 1847. —— cyathiformis HALL. Paleontology of New York, vol. i, p. 72, pl. 25, fig. 6a-6e. Closely related to J. iowensis. Formation and locality.—Trenton limestone ; Carlisle, Pennsylvania. I. CIRCULARIS Hmmons. 1885. Receptaculites circularis Emmons. American Geology, pt. ii, p. 280, fig. 82. 1891. Receptaculites circularis JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 63. This species may be identical with I. Jowensis, but the spicular head plates seem to be larger. Formation and locality. Loraine shales ; New York. I. JONESI Billings. 1865. Receptaculites jonesi BILLINGS. Paleozoic Fossils, vol. i, p. 389, fig. 365. 1865. Receptaculites jonesi BILLINGS. Canadian Naturalist and Geologist, sec. ser. vol. ii, p. 191, fig. 12. 1884, Ischadites kenigii (partim) HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 836, See remarks on this species under J. owensis. Formation and locality.—_Lower Helderberg group ; Cape Gaspé, 66 1859. 1883. 1887. 1861. 1866. 1867. 1870. 1875. 1875. 1884. THE PALEONTOLOGY OF MINNESOTA. {Ischadites. I. SQUAMIFER Hall. e Dietyocrinus squamifer HALL. Paleontology of New York, vol. iii, p. 135, pl. 7A, figs. 11, 18. Receptaculites squamifer HALL. Second Ann. Rep. N. Y. State Geologist, pl. 23, figs. 1, 2. Ischadites squamifer HALL. Paleontology of New York, vol. vi, p. 291, pl. 24, figs. 1, 2. Formation and locality. Lower Helderberg ; Schoharie, New York. I, TESSELLATUS Winchell and Marcy. . Receptaculites infundibulum HALL.* Report of the Superintendent of the Geological Survey of Wisconsin, p. 16. Ischadites tessellatus WINCHELL and MARCY. Memoirs Boston Soc. Nat. Hist., vol. i, p. 85, pl. 2, fig. 3. Ischadites tessellatus HALL. Twentieth Rep. N. Y. State Cab. Nat. Hist., pp. 390, 395. Receptaculites formosus MEEK and Wor?THEN. Proc. Acad. Nat. Sci. Philadelphia, sec. ser vol XIV, p. 22. Receptaculites formosus MEEK and WoRTHEN. Geological Survey of Illinois, vol. iv, p. 500, pl. 24, fig. 1. Ischadites tessellatus GiMBEL. Abhandl. der. k. bayer. Akad. der Wissensch., bd. xii, p. 40. Ischadites tessellatus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 839. The pear-shaped form and the large spicular head-plates readily separate this from all other Amer- ican species of the genus, except J. canadensis Billings, which will probably prove to be a synonym. Formation and locality.—Niagara limestone ; near Chicago, Lllinois, and Racine, Wisconsin. 1863. 1865. 1865. 1880. 1884. I. CANADENSIS Billings. Ischadites canadensis BILLINGs. Geology of Canada, p. 309, flg. 313, and p. 327 (not described). Receptaculites canadensis BILLINGS. Paleozoic Fossils, vol. i, p. 384, fig. 362 (not described). Receptaculites canadensis BILLINGs. Canadian Naturalist and Geologist, sec. ser. vol. ii, p. 191, fig. 10. 3 is Receptaculites canadensis RoMER. Lethzea Palaozoica, p. 289. Receptaculites ? canadensis HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 844. Probably identical with J. tessellatus, in which case this name wil] have precedence, provided, how- ever, that a figure without a description is regarded as sufficient for establishing a species. Formation and locality.—Niagara limestone ; township of Esquesing, Ontario, Canada. 1863. 1879. 1882. 1884, I. SUBTURBINATUS Hall. Receptaculites subturbinatus HALL. Transactions Albany Institute, vol. iv, p. 224. Receptaculites subturbinatus HALL. Twenty-eighth Rep. N. Y. State Mus. Nat. Hist., p. 103, pl. 3, figs. 1-3. Receptaculites subturbinatus HALL. Hleventh Rep. State Geologist of Indiana, p. 221, pl. 2, figs. 1-3. Ischadites koenigii (partim) HInDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 836. This species is regarded as a synonym of I. kenigii by Hinde (ep. cit.). Formation and locality.—Niagara group ; Waldron, Indiana. 1861. 1875. 1882. 1884. I, HEMISPHERICUS Hail. Receptuculites hemisphericum HALL. Report of the Superintendent of the Geological Survey of Wisconsin, p. 16. Reeeptaculites ohioensis HALL and WHITFIELD. Palxontology of Ohio, vol. ii, p. 123, pl. 6, fig. 1. Receptaculites hemisphericum WHITFIELD. Geology of Wisconsin, vol. iv, p. 269, pl. 13, fig. 4. Ischadites kenigii (partim) H1NDE. Quart. Jour. Geol. Soc. London, vol. x1, p. 836. This is also regarded asa synonym of J. kewnigii by Dr. Hinde. Formation and locality.—Niagara limestone ; Racine and Waukesha. Wisconsin, and Yellow Springs. Ohio. *Since this species was accompanied by a poor description, and without figures, we prefer to use the name J. tessellatus forit. Dr. Hinde (op. cit. p. 839) says regarding R. infundibulum, ‘in the absence of figures, mere verbal description, like Hall’s, of the fossils of this group is quite insufficient for the recognition of species, more particularly when the character of the fossil is so little understood by the author that he regards the base of the fossil as its summit, and vice versa.” Meek and Worthen (Geol. Survey of Illinois, vol. iii. p. 302) also say that they were unable to identify “several allied forms already named and described from these rocks, and not yet figured.” SPONGES, GRAPTOLITES, CORALS. 67 Lepidolites, Cerionites. ] LEPIDOLITES, Ulrich.* PLATE F, FIGS. 11, 12. 1879. Lepidolites, ULricu. Jour. Cincinnati Soc. Nat. Hist., vol. ii, p. 20. 1885. Ischadites, JAMES. Ibidem, vol. viii, p. 163. 1891. Receptaculites, JAMES. Ibidem, vol. xiv, p. 60. Lepidolites is closely related to Ischadites, but possesses a few features that will not allow it at present to be regarded as synonymous with the latter. The spicular head-plates in Ischadites Dr. Hinde (op. cit. p. 812) describes as follows: “As arule the margins of the plates appear to fit closely and evenly to each other so as not to leave any interspace between their edges, but in some cases the upper or front mar- gins seem to be slightly elevated as if they imbricated over the lower or hind margins of the spicular plates immediately in front, and left a small intermediate space, now filled with the matrix.” The head-plates in Lepidolites are very thin, strongly imbricating and wavy along their edges. While these sponges are more or less distorted, this overlapping character of the plates cannot be ascribed to pressure. Again, in Ischadites the head-plates increase in diameter from the nucleus to the zonal region, and then decrease in size towards the summit, but in Lepidolites, they gradually become larger from the center of the base to the upper portion of the sponge. The vertical or fifth ray of the spicules in Lepidolites is very short and terminates bluntly, while in Jschadites it is long and slender, gradually tapering and terminating in a point. This ray (the fifth) does not project free into the cavity, but lies flat and directed downward, with neighboring ones side by side, so that the result of the arrangement is an imbrication comparable with narrow shingles. L. proxHautti Ulrich. 1879. Lepidolites aickhauti ULRicH. Jour. Cincinnati Soc. Nat. Hist., vol. ii, p. 21, pl. 7, figs. 17-17b. 1879. Lepidolites clongatus ULRIcH. Ibidem, p. 22, pl. 7, fig. 16. 1885. Ischadites dickhauti JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. viii, p. 165. 1891. Receptaculites dickhauti JAMES. Ibidem, vol. xiv, p. 63. Mr. Ulrich agrees that the name ZL. elongatus is superfluous. Formation and locality—Cincinnati group ; Covington, Kentucky. CERIONITES, Meek and Worthen. 1868. Cerionites, MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 346. Type Lunulites? dactylioides OWEN. C. DACTYLIOIDES Owen, sp. 1844. Lunulites ?dactioloides OWEN. Geological Report Lowa, Wisconsin and Illinois, p. 69, pl. 13, fig. 4. 1868. Cerionites (Pasceolus?) dactylioides MEEK and WoRTHEN. Geological Survey of Illinois, vol. iii, p. 346, pl. 5, fig. 2. 1884. Cerionites dactyloides WHITFIELD. Geology of Wisconsin, vol. iv, p. 267, pl. 13, figs. 1-3. Formation and locality.—Niagara limestone ; Carroll county, Illinois, and Waukesha, Wisconsin. *We are indebted to Mr. Ulrich for the opportunity of studying his type material. 68 THE PALEONTOLOGY OF MINNESOTA. [Anomalospongia. Pasceolus Billings (Geological Survey of Canada; Report of Progress for 1857, p. 842), may belong to the Receptaculitide, but we are unable to give a definite opinion regarding its systematic position. ANOMALOSPONGIA, noy. nom. ON THE STRUCTURE AND SYSTEMATIC POSITION OF “ANOMALOIDES,” AND A PROPOSAL TO CHANGE THE NAME TO ANOMALOSPONGIA. BY EH. O. ULRICH. The name Anomaloides reticulatus was proposed by me in 1878 in my first contri- bution to paleontologic science (Jour. Cin. Soc. Nat. Hist., vol. i, p. 92). Viewed as a first effort, some of the errors contained in that paper may be excused, especially since none of them are very bad, and the worst not entirely my fault, as I hope to show in a paper to be published soon. One error, that in the construction of the name Anomaloides, was pointed out by Mr. 8. A. Miller (North Amer. Geol. and Pal., p. 224, 1889). I acknowledge the justice of his criticism, and although similarly con- structed names are allowed to stand, I think it best, now that the nature of the fossil is determined, to change the name. I propose therefore to use Anomalospongia instead. The new name retains the principal part of the original designation, and the ending spongia denominates the class to which the fossil belongs. Nor is Anom- alospongia at all inappropriate, for the specimens now so named are, as will appear later on, still to be regarded as anomalous. ; The original specimens, 35 in number, were all fragments, some large, most of them small, and all found within a space a few feet square in the middle beds of the Cincinnati group at Covington, Kentucky. Further search at the same spot resulted in a few more fragments, all of them small, and, like many of the originals, con- siderably obscured by the adhering clayey matrix. For ten years these specimens remained in my cabinet without further examination, I having been under the im- pression that their structure had been determined as far as the specimens at hand would admit. At last, after the possibility of other affinities than with Echinodermata was suggested, a re-examination was determined upon. This time I began with the fragments that in my original study were cast aside because of the obscuring matrix. Having some experience in cleaning fossils in that condition I succeeded in freeing - several fragments of their clayey investment. The result was most gratifying, since the cleaned surface showed unquestionably a layer of overlapping spicule rays, prov- ing the fossil to belong to the Spongida and not to the Echinodermata. ! SPONGES, GRAPTOLITES, CORALS. 69 Anomalospongia.] Naturally enough, my first supposition was that these horizontal ‘rays would prove four in number, as in Receptaculites and related genera, and it was not till I began to study the enlarged drawing of the surface (here reproduced in fig. 14, on plate F), which I drew at once under the camera lucida. This figure is not diagram- matical, but represents the parts just as they appeared to me in the microscope. As shown in figure 14, we have only three instead of four horizontal rays—a troublesome fact, because it obliges us in the present state of our knowledge to refer Anomalo- spongia to the incerte sedes among the sponges. Had four horizontal rays been pres- ent we might have overlooked certain other peculiarities and placed the genus with the Receptaculitide, but that can scarcely be recommended now, since it would neces- sitate too great an expansion of the characters of that family. Before entering upon a discussion of the relations of the genus to the Receptacu- litide and other organisms, I shall offer the following diagnosis of the genus and remarks upon the only known species : ANOMALOSPONGIA, n. gen. Proposed instead of Anomaloides, Ulrich, 1878, Journal Cincinnati Society of Natural History, vol. i, p. 92. Sponge hollow, ? obconical, that being the shape of the most complete of the fragmentary specimens at hand; the walls consisting of definitely arranged spicular elements. Spicules four-rayed, with a small, knob-like summit, probably to be regarded as an undeveloped fifth ray ; one of them (the vertical) thick and strong, sub- cylindrical or club-shaped, its inner extremity pointed, the outer rounded, and pro- duced centrally into a neck-like prolongation from which three very delicate rays spread horizontally. Vertical rays arranged so as to be perpendicular to the surface and each in contact, yet not organically united, with six of its neighbors; leaving, usually, a small interstice at the angles of junction, and the pointed inner extremity free. Horizontal rays thin, long, tapering toward their extremities, interwoven and overlapping each other three or four times ; each divided longitudinally by a strongly impressed groove, causing them to appear double ; open meshes between these rays normally of triangular shape. Communication between the interior and exterior carried on, apparently, through the small interstices left between the adjoining ver- tical rays. The complete form of Anomaloides reticulatus or, as it should now be called, Anoma- lospongia reticulata, is doubtful. 1t may have been conical, as suggested in the above description, with the base pointed and top open. But it is also possible that it was, 70 THE PALEONTOLOGY OF MINNESOTA. [Anomalospongia. as I believed originally, perhaps triradiate, with a central opening, as in Brachio- spongia. Neither view is supported by positive evidence, so that for the present it seems best to leave that point entirely open. Two of the specimens are depressed-conical in form, one about 50 mm. in length, the other only 22 mm. The larger is 20 mm. wide at the large end, its mar- gins nearly parallel in the upper half and converging rapidly in the lower half. The extreme end may have been closed and pointed, but as both specimens are defective here, it would not be safe to assume that it was. Indeed, it is perhaps just as likely that a small opening existed in the extremity. The smaller specimen is very nearly a duplicate of the lower half of the larger. The relative length and disposition of the three horizontal rays are probably specific peculiarities, hence are mentioned in the generic diagnosis merely in a gen- eral way. In A. reticulata they have a definite form and arrangement, in part, very likely controlled by the arrangement of the vertical rays. The latter form straight or curved transverse and diagonally intersecting rows, generally very regular, and when the horizontal rays are removed by attrition (seemingly a common occurrence) they appear as sub-hexagonal rounded knobs, in most cases with ten or eleven in5 mm. transversely. In three fragments, otherwise apparently identical with the others, the parts are smaller, and in these there are thirteen in that space. Their length, and consequently the thickness of the sponge, is commonly about 2.7 mm., but varies between the observed extremes of 2.0 and 3.4 mm. Since working out the nature of the fossil and its spicular elements, I can detect more or less clear evidences of the horizontal rays on most of the specimens.* In many the exposed rounded end of the vertical ray preserves a triradiate impression of the horizontal rays. In others the rays themselves are preserved but so much pressed that their extension beyond the impressed boundary line between the verti- cal rays is not to be made out. In the best preserved fragments, however, their entire extent, overlapping, and general construction, is shown in as clear a manner as can be hoped for in such delicate structures. From the last specimens, a small portion of the surface of one of which is represented by fig. 14, it appears that one of the horizontal rays is a trifle longer than the other two rays. It is also the one most prominent and oftenest seen, aud overlaps except near its extremity. This may be called the longitudinal ray, since it lies parallel with the length of the conical specimens, while the two others are oblique. When the surface is partly obscured by adhering matrix, the first ray alone is likely to be seen clearly. Viewed through *These remains of the horizontal rays were noticed by me in the 1878 work on the species, but their nature was misin- terpreted because of my erroneous belief that the affinities of the fossils were to be sought for among the Echinodermata. Hence the statement in the original description that there is “‘a minute pit on the top for the articulation of two very fine and small spines.” o SPONGES, GRAPTOLITES, CORALS. 7) Anomalospongia.] a glass of low power, especially in a side light, the surface of such specimens appears to be striated longitudinally. But when the surface is perfectly clean the oblique rays are to be seen dipping under the longitudinal rays. We now come to the consideration of one of the most peculiar features of Anomalospongia, namely, the duplex character of the horizontal rays. Each is in fact divided into two subcylindrical equal parts by a sharply impressed central groove, extending from the central node to their distal extremities, It is not pos- sible that these grooves (there is one on both the upper and lower sides of the rays) can have resulted from pressure. because the condition is too uniform, And I have detected no sign whatever of fractures that would necessarily have resulted from pres- sure. Nor can I see how a cylindrical ray with a large axial canal, such as we would be obliged to assume in that case, could be compressed so as to become equally grooved on both the upper and lower sides. No, after viewing the matter from all sides, I see no other way than to accept the evidence as presented by the speci- mens. After that I believe we are warranted in assuming (1) that the duplex char- acter is a peculiar form of bifureation, (2) that the axial canal is small and (3) dividing at the node, ran independently up each half of the ray. A diagrammatic representation of the parts is given in the accompanying cut (fig. 1). Fig. 1, a, diagrammatic representation of the inner part of the horizontal rays of a spicule of Ano- malospongia reticulata, showing the supposed bifurcation of the rays and axial canals. band ¢, highly magnified top and side views of a surface spicule of a recent lithistid sponge. (Corallistes microtubereulatus Schmidt.) The sponge was probably originally siliceous, but the specimens as now pre- served are crystalline calcite. As regards the systematic position of Anomalospongia the Receptaculitide are deserving of first consideration ; not so much because of a closeness of relationship as that “Anomaloides” has been referred to that family, indeed, a certain author has been indiscreet enough to place that name among the synonyms of Receptaculites! The first essential of the Receptaculitide ave the rhomboidal or hexagonal summit plates, which have been regarded by Hinde (see quotation ante p. 55) perhaps cor- rectly, as modified spicule rays. In Anomalospongia the abortive fifth ray is reduced precisely as in some hexac- tinellid sponges, to a mere knob, and therefore compares no nearer with the summit =~] bo THE PALEONTOLOGY OF MINNESOTA. [Anomalospongla. plates of the Receptaculitide than does the knob-like sixth ray sometimes seen in Hyalostelia smithit Young and Young, sp., and but little better than in the numerous sponges in which the summit ray is wanting entirely. On the whole it compares best with the condition commonly presented by the surface spicules of lithistid sponges. (See fig. 1b and c¢.) The next point to be compared is the horizontal rays. A fundamental difference is at once evident in this, that in the Receptaculitide there are four of them arranged at right angles so as to form quadrangular interspaces ; while in Anomalospongia there are only three, with the interspaces triangular. In the Receptaculitidw, too, the horizontal rays overlap not at all or only sparingly, and when they do the over- lapping extremities lie side by side and parallel with each other, and not, as in Anomalospongia, over each other. In the latter the crossing and interweaving of the rays is a marked feature, and not even approximated by the conditions prevailing in the Receptaculitidw. As regards their duplex character in Anomalospongia it suf- fices to say that nothing of the kind is known in any of the Receptaculitidw. The vertical or entering ray of Anomalospongia is on the whole very similar to that ray in Receptaculites, but even more like that in Ischadites, and, if true relation- ship exists between them, it is here that we find it expressed with much greater obviousness than in any other feature held in common by them. Still, even here some important differences are apparent. In Ischadites, which as said presents the greatest resemblance to Anomalospongia, and therefore alone need be compared, the vertical rays are entirely separate from each other, and project freely into the central cavity, the continuity of the wall being formed in part by contact between the horizontal rays, but mainly by the overlapping summit plates. In A. reticulata, on the contrary, each vertical ray is in contact, normally, with six of its neighbors, so that the task of maintaining the shape of the sponge, was performed chiefly by this part of the spicules. Other points of difference are noticed in the uniform size and in the arrangement of the spicular elements of Anomalospongia when compared with the true Receptacu- litide.* In the latter they are small at the nucleus and increase gradually in size to the periphery ; with the arrangement in regular curved intersecting lines closely simu- lating a common style of engraving on watch cases. In Anomalospongia, however, the pieces are of nearly the same size on all parts, and the arrangement that merely which would result from placing equal hexagonal pieces in contact with each other on all sides. A feature in which Anomalospongia agrees with Receptaculites, but not more so than with other very different sponges (Geodia clavata Hinde), is the peculiar neck-like *Not applicable to Spwrospongia, Pengelly, which it seems to me has little claim to association in the same family with Receptaculites, © SPONGES, GRAPTOLITES, CORALS. 73 Anomalospongia.] constriction of the vertical ray immediately beneath the horizontal rays. This is relatively greater in Anomalospongia than in any other form known to me, To resume: we have among the differences (1) the total absence of summit plates, (2) three instead of four horizontal spicular rays, (3) the duplex character, and (4) the interweaving of the horizontal rays, (5) the contact between the club-shaped vertical rays, and (6) the uniform size and different arrangement of the spicules. Opposed to these we have as points of agreement, (1) the form and comparatively large size of the vertical or entering ray, (2) its arrangement in the sponge-wall per- pendicular to the surface, and (3) the possession of relatively small horizontal rays. This concise statement of the points of likeness and of difference is I believe sufficient to show that Anomalospongia cannot be placed in the same family with Receptaculites. Still, 1 am satisfied that real relationship, however remote, exists between them. As I now view the matter it seems advisable to introduce a new order for the reception of the Receptaculitidw, Anomalospongia, and also Amphispongia, Salter ; the relations between the last two seeming to be, as I will endeavor to show presently, closer than might be suspected from a casual comparison. The new order would be strictly paleozoic, and, excepting a few forms that sur- vived into the Devonian and possibly later, would be essentially Silurian. It would therefore comprise only early types that, in common with nearly every class of animals represented in paleozoic times, may be called comprehensive because they _combine characters which in more recent times became separately developed and diagnostic of now widely different groups of genera and families. Perhaps the most striking diversity in these respects, shown by the forms in question, is the difference in the number of horizontal rays pertaining on the one hand to the Receptaculitide with four, and on the other to Anomalospongia with three. In the number and disposition of their rays the spicules of Anomalospongia remind us of true Tetractinellide. 'They also resemble, perhaps even more, the trifid surface spicules (“Gabel-Anker”) of many lithistid sponges. The horizontal rays in the latter often are bifurcate close to the centre, so that even the duplex character of these rays in Anomalospongia is in a measure simulated. (See fig. lb and.) I am not prepared to decide definitely that these resemblances are or are not indica- tive of relationship. It seemed desirable, however, to mention the facts, since they illustrate the sense of the preceding paragraph. As already indicated, it is my belief that the uncertain Amphispongia is related to Anomalospongia—indeed, that the two might well be united in one family. That genus was proposed by Salter* for certain free, compressed, elongate-elliptical masses, rounded at both ends, and rarely more than 50 mm. long by 18 mm. wide, which *Mem. Geol. Sur. Gt. Britain. 32, Scotland, p. 135, 1861. 74 THE PALEONTOLOGY OF MINNESOTA. {Anomalospongla occur in Silurian strata near Edinburg, Scotland.* From Hinde’s description and remarks on the only known species, A. oblonga Salter, (Catal. Foss. Sponges, Brit. Mus., p. 154, 1853) we learn that the lower half of the sponge is composed of “closely approximated, straight, elongated, conical spicules, about 3 mm. in length, and from .75 to 1 mm. in width, arranged so that their rounded summits form the outer surface of the sponge, whilst their obtuse points reach to its central axis.” The upper part of the sponge is said to consist of small cruciform and five- (possibly six-) rayed spicules, and of very minute filiform mon-axial spicules, while “in one speci- men there are indications of an exterior surface-layer of filiform spicules regularly arranged in the direction of the length of the sponge.’ The spicules seem in no case to have been organically attached to one another, nor are canals present, but a narrow tubular cloacal cavity was detected in the lower part of a few specimens. Salter regarded the spicules as triradiate, and Hinde admits that when not detached from the mass “only casts of three rays are exposed.” The surface of the upper part, as figured by Hinde (op. cit.) resembles part of the surface of casts of species of Jschadites so closely that it is a matter of surprise that so keen an observer as Dr. Hinde failed to make a note of it in his memorable work on the Receptaculitida. The supposed surface-layer, with its longitudinally arranged filiform spicules, causes me to think it possible that the horizontal rays in A. oblonga may really be, as in Anomalospongia, three in number, with the longitudinal ray the strongest. At any rate it would be well to re-examine Amphispongia oblonga in the new light fur- nished by Anomalospongia reticulata. The club-shaped spicules of the lower part of the sponge are too much like the vertical ray of the spicules of Anomalospongia to be without significance entirely. My impression is that the lower spicules of Amphi- spongia ave not really mon-axial, but will be found to have head rays similar to if not precisely like those of Anomalospongia. Further, is it not possible that the same kind of entering rays (only smaller, perhaps,) occur in the upper part of the sponge as well, being covered there by the matrix which may intervene at a constriction just beneath the horizontal rays, and thus present to view the casts of the latter only ? Again, it is possible that the so-called “upper part” of A. oblonga may really owe its comparative smoothness to the development of a dermal layer consisting of small cruciform and filiform spicules. But this is only speculation. What is wanted are facts showing the true condition of things in Amphispongia, and I hope some of our British paleontologists will favor us with a full account of them. In the meantime we can use only the close approximation and the shape and size of the spicules of the lower part in showing the relationship which I am satisfied will sooner or later be proven to exist between the two genera. *The specimens are moulds in shaly rock merely, the sponge spicules themselves having been dissolved completely away. SPONGES, GRAPTOLITES, CORALS. 75 Rauffella.] Family DICT YOSPONGIDA®, Hatt. RAUFFELLA, Ulvich. PLATE F, FIGS. 16-20. 1889. Rauffella, ULR1cu. American Geologist, vol. iii, p. 235. Original description.“ Sponges free (?) forming hollow cylindrical stems, or radially arranged leaves. Wall exceedingly thin, composed of two distinct layers of spicule-tissue. Inner layer minutely porous, the pores irregularly distributed, of unequal size, the larger ones rounded, the smaller ones much more numerous and mostly of irregularly angular outline ; spicular tissue separating pores thin, the nature of its elements undetermined. Outer layer consisting of a network of large spicules, apparently of a curiously modified hexactinellid type. Usually they appear as irregularly coalescing thread-like striz lining the surface im a longitudinal direction, with more slender connecting filaments traversing the narrow intervening spaces at more or less acute angles, leaving acutely elliptical depressed spaces. At other times the strizw cross each other diagonally, producing an appearance not much unlike that of the ordinary arrangement of the spicules in the Dictyospongidw. “Type R. filosa Ulrich.” RavuFFetyia FILOSA Ulrich. PLATE F, FIGS. 16-18. 1889. Rauffella filosa ULRIcH. American Geologist, vol. iii, p. 237, figs. 1, 2, 4. Original description—‘Sponge forming a straight or slightly curved hollow cylindrical stem, 10 to 15 mm. in diameter. The largest fragment seen is 90 mm. in length. One of the ends (whether the upper or lower one, has not been determined) is rounded off somewhat like the tip of a finger. The other, probably, was open. Sponge wall less than 0.5 mm. in thickness. Outer surface generally appearing to the naked eye as stiongly striated longitudinally. Under a good pocket lens numer- ous connecting filaments are noticeable forming with the stronger threads an irregu- lar, narrow-meshed net-work. Nearly every specimen, however, exhibits on limited portions of the surface a comparatively regular arrangement of the spicular tissue in diagonally intersecting lines. Here the hexactinellid character of the spicules is determined, there being, apparently, four rays spread horizontally and one extend- ing downward into the inner tissue, while the sixth is not developed. The spicules are joined together by a union of the horizontal rays of each with those of four 76 THE PALEONTOLOGY OF MINNESOTA. 2 (Ruffella. other spicules in such a manner that a network with rhomboidal meshes is formed. Similar but smaller spicules are developed in the interspaces. This regular arrange- ment of the spicules is but rarely met with, the surface appearing, as already stated, usually to be striated in a longitudinal direction mainly. On an average eleven of the striz occur in 5 mm. transversely. “Inner layer of sponge tissue exceedingly thin and minutely porous. Its struct- ure has not been determined, the finer details having been obliterated during: the process of fossilization. “This sponge cannot be confounded with any other fossil known to me from Cambrian or Silurian rocks, its finger-like form and the strong thread-like striations of the surface giving it a very characteristic and easily recognized aspect.” Formation and locality.—Common in the Trenton shales at Minneapolis, St. Paul, Oxford Mills, Fountain, Preston, and near Marion, Minnesota; Decorah, Iowa. ?In the Galena shales, six miles south of Cannon Falls, Minnesota. Collectors. —Miss Cora E. Goode, E. O. Ulrich, C. L. Herrick, J. C. Kassube, W. H. Scofield, and the writers. Mus. Reg. Nos. 712, 718, 8491, 4946, 5020, 7702-4, 7707, 7708. RAUFFELLA PALMIPES Ulrich. PLATE F. FGS. 19, 20. 1889. Rauffella palmipes ULRICH. American Geologist, vol. iii, p. 288, fig. 3 on p. 236. Original description.— Sponges rather large, originally probably of inverted pear- shaped outline, consisting of five bi- or tri-furcating compressed lobes springing from a short stem, united at the center and arranged in a radial manner. In the fossil state they present varied forms corresponding with the degree and direction of the compression they have suffered. This is much less than might be expected of so frail an otganism, and I can account for the comparatively good preservation of the shape only by supposing the lower extremity of the stem to have been open, thus permitting the material that made up the strata (mud, fragments of shells, bryozoa, etc.) to enter freely into the internal cavity. Generally, the cavity is entirely filled with material of the same nature as the surrounding matrix. In a few cases free communication must have been interrupted causing a lobe to remain empty and now to appear much more compressed than usual. On account of the friable nature of the shales in which they are found, most of the specimens are mere frag- ments. Still, after a careful search, the author succeeded in securing three nearly complete examples. ‘l'wo of these are compressed obliquely with the stem on one side, and look very much like the webbed foot of a bird. The specific name was SPONGES, GRAPTOLITES, CORALS. Oe Cylindrocelia.] suggested by this fancied resemblance. The third is compressed vertically and shows the radial arrangement and bifurcation of the compressed lobes very satis- factorily. As near as can be determined, the original dimensions of a specimen of medium size were about as follows: hight, 90 mm.; greatest width, 80 mm.; dia- meter of stem 15 mm.; thickness of lobe, 8 mm.; thickness of walls of sponge, 0.5 mm., or less. “The spicules of the inner layer, owing to alteration and replacement by calcite, have not been determined. A thin section, however, shows that it was minutely porous, the tissue separating the pores thin, and the pores of variable size, the larger ones of rounded form, the smaller ones more or less angular. The surface, as in R. filosa, is striated, only the striz are much finer and more irregular. The appearance of the surface is to be described as hirsute rather than filose.” Formation and locality —From the Trenton shales at Minneapolis and St. Paul, Minnesota. Collector.—Mr. BE. O. Ulrich. Mus. Reg. No. 8225. Order CALCISPONGI AS, * Blainville. Family PHARETRONHES, Zittel. CYLINDROCGLIA, Ulrich. 1889. Cylindrocelia, ULRicH. American Geologist, vol. ili, p. 245. 1891. Cvylindrocelia, JAMES. Jour, Cincinnati Soc. Nat. Hist., vol. xiv, p. 56. Original description.— Sponges free, cylindrical, or nearly so, with the lower end tapering rapidly to a point, or truncate. A central cloaca extends throughout at least the subcylindrical portion. It is of tubular or very elongate conical form, widening gradually upwards. Walls thick, traversed by irregularly disposed radi- ating canals. Very few of these penetrate the thin and compact dermal layer which covers both the inner and outer surfaces. When the dermal layer is worn away their sub-circular mouths appear. Skeleton, apparently very finely porous. The specimens are too much altered to admit of determining its elemental component. “Type, C. endoceroidea Ulrich. “Sponges of this genus are liable to confusion with slightly tapering forms of Orthoceras and Endoceras. The absence of septa and presence of canals should, of course, distinguish them at once.” *The systematic position of these sponges is that of Mr. Ulrich, Geol. Survey of Illinois, vol. viii, p. 239, 1890. 78 THE PALEONTOLOGY OF MINNESOTA. [Heterospongi CYLINDROC@LIA MINNESOTENSIS Ulrich. PLATE G, FIGS. 1-3. 1889. Cylindrocelia minnesolensis ULRICH. American Geologist, vol. ili, p. 248. Original description —‘ This species differs from the preceding ones | C. endoceroidea, C. covingtonensis| in being almost perfectly cylinderical (7..e. allowing for a slight amount of compression apparent in all the specimens), the average taper in a length of 40 mm. being rarely more than 1 mm. Most of the fragments vary in diameter between 10 and 15 mm., but it is sometimes a mm. more or less. . Basal extremity not satisfactorily shown in any of the specimens; apparently truncate. The cloaca must have been narrow since it, like the internal portion of the canal system, has in every case been entirely obliterated by the crystallization of the calcite of which the specimens are composed. The surface is smooth and may, according as the der- mal layer remained or had been removed at the time of fossilization, exhibit very few or comparatively abundant canal apertures—more irregularly distributed, how- ever, and not nearly so numerous as in the other species. The canals are rounded and vary in diameter from less than 1 to 2.5 mm.” Formation and locality.—Rare in the Trenton shales at Minneapolis, St. Paul, and Fountain, Minne- sota. Occurring also at the base of the Galena shales, six miles south of Cannon Falls, Minnesota. Collectors.—E. O. Ulrich and W. H. Scofield. Mus. Fieg, No. 7709. HETEROSPONGIA, Ulrich. bs 1889. Heterospongia, ULRicH. American Geologist, vol. iii, p. 239. 1891. Heterospongia, JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 71. Original description— “Sponges consisting of sublobate or irregularly divided compressed branches. Entire surface exhibiting the mouths of branching and more or less tortuous canals, which begin near the center, where they are nearly vertical, and proceed toward all portions of the surface in a curved direction. A limited num- ber of oscula, distinguished from the ordinary canals by being larger and surrounded by radiating channels, occasionally present. ‘Sponge skeleton between the canals of variable thickness, sometimes appearing nearly solid, at other times composed of loosely interwoven spicule fibers. None of the specimens show the spicules in a satisfactory manner. From the traces seen it would appear that they are mostly very small and of the three-rayed type. “Type, H. subramosa Ulrich.” SPONGES, GRAPTOLITES, CORALS. 79 Hindia.] HETEROSPONGIA SUBRAMOSA ? Ulrich. PLATE G, PIGS, 4-6. 1889. Heterospongia subramosa ULRicH. American Geologist, vol. iii, p. 240, fig. 6 on p. 236. 1891. Heterospongia subramosa JAMES. Jour. Cincinnani Soc. Nat. Hist., vol. xiv, p. 71. Original description —* Sponge subramose, occasionally palmate ; branches more or less flattened, from 9 to 13 mm. thick and 11 to 30 mm. wide. The largest speci- men seen is 65 mm. high and 45 mm. wide. Surface generally even, exhibiting the rather irregularly distributed canal apertures. These are generally of very unequal sizes, though on limited portions of the surface, both their distribution and size may be fairly regular. The average diameter of an aperture is nearly 0.7mm., with about 5in 5mm. The width of the interspaces between the canal mouths is equally variable, the extremes being 0.2 and 1.2 mm. The sponge skeleton is composed of more or less loosely interwoven spicule-fibres, but in the usual state of preservation in the inter—-canal spaces appear quite solid and structureless. In none of the speci- mens are the spicules sufficiently well preserved to make their determination a matter beyond dispute.” Formation and locality.—Rare in the Hudson River group at Spring Valley, Minnesota. Common in the same formation in Marion and Lincoln counties, Kentucky. Collector.—E. O. Ulrich. Type in Mr. Ulrich’s collection. Order LITHISTID AS, Schmidt. ? Family THTRACLADINA, Zittel. HINDIA, Dunean. 1879. Hindia, DUNCAN. Annals and Mag. Nat. Hist., fifth ser. vol. iv, p. 84. 1883. Hindia, HINDE. Catalogue Fossil Sponges, British Museum, p. 57. 1886. Hindia, RAUFF. Sitzungsb. der Niederrh. Gesell. zu Bonn; Sitzung vom 10 Martz. 1887. Hindia, H1INDE. Annals and Mag. Nat. Hist., fifth ser. vol. xix, p. 67. 1890. Hindia, ULRicn. Geol. Survey Illinois, vol. viii, p. 226. 1891. Hindia, JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 56. Hinpia parva Ulrich. PLATE G, FIGS. 7-9. 1889. Hindia parva ULRicH. American Geologist, vol. iii, p, 244. 1889. Microspongia parva MitLER. North American Geology and Palwontology, p. 161. 1891. Microspongia gregaria (partim) JAMES, Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 54. Original description—* Sponges free, globular in form, with an even rounded surface. Specimens vary between 5 and 10 mm. in diameter, but im a large propor- tion of the specimens seen, the diameter varies but little from 7 or 8 mm. 80 THE PALEONTOLOGY OF MINNESOTA. {[Solenopora. “The radiating canals are a little smaller than in the common H. spheroidalis Dunean, of the Niagara, being as a rule not over 0.27 mm. in diameter. H. inequalis Ulrich, from the lower or sponge beds of the Trenton limestone at Dixon, Illinois, is larger and has, as its name may indicate, radiating canals of very unequal size.” The specimens of this species occurring in the Galena of Keutucky, Tennessee, Wisconsin, and Minnesota, the localities from which Mr. Ulrich obtained his mate- rial, should not at present be regarded as belonging to Microspongia gregaria Miller and Dyer. ‘The latter is not shown to be identical with Hindia, and, as the Galena specimens undoubtedly belong to the last named genus, there is no evidence that H, parva is synonymous with Microspongia gregaria. The varieties of Hindia parva found at Cincinnati and Middletown, Ohio, of which Mr. Ulrich writes op. cit., p. 243), may be the same as Miller and Dyer’s species, but this the writers cannot prove, as they have no material from Ohio for comparison. Formation and locality.—Rare in the Trenton shales at Minneapolis, Minnesota. Not uncommon in the Galena of Goodhue county, Minnesota, and Oshkosh, Wisconsin. Also from a similar horizon at Dan- ville and Frankfort, Kentucky, and south of Nashville, Tennessee. Collectors—W. H. Scofield, E. O. Ulrich and C. Schuchert. Mus. Reg. No. 7711. f ? Class HY DROZOA. ?Sub-Class H YDROIDA. SOLENOPORA, Dybowski. SoLeNoporA compacta billings. PLATE F, FIGS. 21-23. 1862. Stromatopora compacta BILLINGs. Paleozoic Fossils, vol. i, pp. 55, 210. ? 1877. Tetradium peachti NICHOLSON and ETHERIDGE. Annals and Magazine of Natural History, ser. iv, vol. xx, p. 166. ? 1877. Solenopora spongioides DyBowski. Die Chetetiden der ostbaltischen Silur Formation, p. 124, pl. 2. 1879. Solenopora(?) compacta DAWSON. Quart. Jour. Geological Society, London, vol. xxxv, p. 53. 1883. Tetradium peachii, var. canadense Foorp. Contribution Micro-Pal. Silurian Rocks of Can- ada, p. 24. 1885. Solenopora compacta NICHOLSON and ETHERIDGE. Geological Mag., dec. iii, vol. ii, p. 529. 1888. Solenopora compacta NicHOLSON. Ibidem, vol. v, p. 15. 1889. Solenopora compacta NICHOLSON. Manual of Palwontology, vol. i, p. 201, figs. 88a-83d. Original description. This species forms small sub-globular masses, from | to 2 inches in diameter. ‘The concentric lamelle are thin and closely packed together, there being in some specimens from 6 to 12 layers in the thickness of 2 lines.” The internal structure is described by Dr. Nicholson as follows: “Composed of radiating capillary tubes, arranged in concentric strata. The tubes vary from SPONGES, GRAPTOLITES, CORALS. 81 Diplograptus.] i to 4; mm. in size, and are in direct contact throughout, no interstitial tissue of any kind being developed. The tubes are irregular in form, with thin, often undu- lated walls, which are not pierced by any apertures or pores, but are often crossed by more or fewer transverse partitions or “tabule.’ Very commonly the tubes exhibit more or fewer inwardly directed partitions, which extend to a greater or less distance into the cavity of the tube, and are the result of the cleavage or ‘ fission’ of the tubes.” Formation and locality—Rare in the Trenton shales near Cannon Falls, Minnesota; Frankfort, Kentucky and Nashville, Tennessee. In the Black River group at Pauquette Rapids on the Ottawa river, and island of Montreal, Canada. In division L, Newfoundland. Dr. Nicholson says it has also been found in Great Britain and Russia. Mus. Reg. No. 8055. Sub-Kingdom COREE NCH IR APA Class VY DROZOA.. Sub-class GRAPTOLITOIDEA. Family DIPLOGRAPTID Ai, Lapworth. DreLocraptus pristis? (Hisinger) Hall. 1837. Prinotus pristis HISINGER. Letheea Suecica, p. 114, pl. 35, fig. 5. 1847. Graptolithus pristis HALL. Paleontology of New York, vol. i, p. 265, pl. 72, figs. la—Is. 1863. Graptolithus pristis BiLLInes. Geology of Canada, p. 200, fig. 195. 1865. Graptolithus (Diplograptus) pristis HALL. Canadian Organic Remains, dec. ii, p. 15, fig. 3b: p. 109, figs. 21, 30. Fa 1867. Graptolithus (Diplograptus) pristis HALL. Twentieth Rep. N. Y. State Cab. Nat. Hist., pp, 182, 205, figs. 22, 32. 1875. Diplograptus pristis NICHOLSON. Paleontology of the Province of Ontario, p. 38. Prof. Hall gives Hisinger’s description of this species as follows: “Linear, straight, scarcely a line broad, compressed; rachis central, capillary; both sides with broad acute teeth’ (op. cit. 1847). —6 82 THE PALEONTOLOGY OF MINNESOTA. [Climacograptus. Formation and locality.—Very common in the lower portion of the Hudson River group, in a small quarry two miles west of Granger, Minnesota. It also occurs in the Utica slate and Hudson River group at Baker’s Falls, Utica, Trenton, Loraine, Turin, and elsewhere in New York; Whitby and Collingwood, Ontario; ? Cincinnati, Ohio, and Graf, Iowa. Collectors.—W. H. Scofield and the writers. Mus. Reg. Nos. 7755, 7756, 7758. DipLoeraptus putittus Hall. Fig. 3. 1865. Graptolithus (Diplograptus) putillus HALL. Canadian Organic Remains, dee. ii, p. 44, pl. A, figs. 10-12, : 1867. Graptolithus (Diplograptus) putillus HALL. Twentieth Rep. N. Y. State Cab. Nat. Hist., pl. 2, figs. 10-12. Formation and locality—Hudson River group, near Granger and near Spring Valley, Minnesota; Graf, Iowa. Collectors.—W. H. Scofield and the writers. Mus. Reg. Nos. 302, 4097, 7758, 7760. Crimacoaraptus typicaLis Hall. Fie. 4. 1865. Climacograptus typicalis HALL. Canadian Organic Remains, dec. ii, pl. A, figs. 1-9. 1867. Climacograptus typicalis HALL. Twentieth Rep. N. Y. State Cab. Nat. Hist., pl. 2, figs, 1-9. Formation and locality.—In the Galena limestone at Mantorville, and Weisbach’s dam near Spring Valley, Minnesota; ?Wisconsin. Cincinnati group at Oincinnati, Ohio; Hudson River group, New York. Collectors.—W. H. Scofield and the writers. Mus. Reg. Nos. 294, 295, 390, 7759. SPONGES, GRAPTOLITES, CORALS. 83 Lichenaria.] Class © ACTINOZOA.* Order ZOANTHARIA. Sub-order MADREPORARIA, Section MADREPORARIA APOROSA, Family ASTRAQID AN, ’ LICHENARIA TYPA, gen. et. sp. nov.+ PLATE G, FIGS, 10-13. Corallum growing in small, irregular, hemispheric colonies, not exceeding 20 mm in diameter, attached by its entire under side to species of monticuliporoids. Ad- dition of new corallites takes place, either interstitially or along the periphery, from underneath the marginal individuals. Walls of the corallites thin, imperforate. Corallites polygonal, inconstant, small but variable, the average adult size about 1 mm. or a little less in diameter, but in the largest specimens may vary from that size to 1.75 mm. in diameter. Tabulz always few, perhaps occasionally wanting ; when present they are horizontal and complete. Septa not developed; rarely two or three very faint longitudinal lines can be observed on each face of the calyx. We know of no compound massive coral in Lower Silurian rocks with which this species need be compared. All have more or less strongly developed septa excepting Lyopora favosa Nicholson and Etheridge, jun.{ In that species the septa are “rudimentary, often wanting in individual calices, varying in number from two or three up to ten or twelve or more, always abortive, and represented only by rough and blunt ridges on the interior of the wall.” (Nicholson, op. cit., p. 190.) Lyopora favosa differs however from Lichenaria typa in its very much thickened walls and in the mode of growth of the colony which was “ rooted at its base to some for- eign body, and the diverging corallites seem to have opened over the whole of the free surface, no traces of an epitheca having come under my observation.” (Nich- olson, op. cit., p. 190.) Species of Columnaria are distinguished from Lichenaria typa by their well developed alternately large and small septa, which extend nearly to the centre of the corallites in the type species. Columnaria incerta Billings§ is *The classification here given for the corals is that of Dr. Nicholson ; ‘Manual of Palawontology, vol. i, pp. 240-345, 1889. +Lichenaria from leichen, tree-moss, and aria, the latter portion of Columnaria, its most likely relative. +Mono. Sil. Foss. Girvan, p. 26, pl. 2, figs. 1-le, 1878. Nicholson, Pal. Tab. Corals, p. 190, pl.8, figs. 3, 3a ; pl. 9, figs. 2, 2a, 1879. Canadian Nat. and Geol. vol. iv, p. 428, figs. 1, 2, 1859. 84 THE PALEONTOLOGY OF MINNESOTA. (Lichenaria. a species probably without septa, but the corallites are described as “slender cylin- drical tubes which may be in contact or separate”, and “the aspect of the species is remarkably like that of Syringopora.” — Small colonies of Lichenaria typa look much like a mass of Conchicolites flexuosus Hall, as figured by Prof. Hall (Pal. New York, vol. vii, pl. cxv, fig. 19). The apertures of the latter are also polygonal in outline, but beyond this the two species are totally unlike. A very small colony of this species, figured on plate G, fig. 11, has given off a single corallite in a manner which is characteristic of Aulopora? trentonensis, n. sp. This corallite has developed three other buds, which have elevated the calyx of the parent, as in Aulopora. Where there are no young corallites infringing upon it, the , wall is circular in outline, with three distinct angles along the side from which the buds have originated. The polygonal outline of the cells of compound corals is prob- ably due to lateral crowding of the corallites. In nearly every case observed by us, when the cells are round in outline, they stand out free from the colony.* Formation and locality.—Not rare in the Trenton shales near Minneapolis, Minnesota. Mr. Ulrich writes us that he has specimens which ‘undoubtedly belong to this genus and probably are specifically the same as typa, from the Black River limestone at Pauquette Rapids, Canada.” Collectors.—E. O. Ulrich and C. Schuchert. LicHENARIA MINOR, 2. sp. (Ulrich.) Fig. 5. Fig. 5. Lichenaria minor Ulrich, Trenton shales, near Cannon Falls, Minnesota. a, an example of this species, growing as usual upon a ramose bryozoan ; b, small portion of same with the corallites opening more direct than usual, x3. Corallum attached parasitically to foreign bodies (chiefly ramose bryozoa) over which it forms irregular patches 1 mm. or a little more in thickness. Corallites comparatively small, of unequal size, irregularly distributed, their apertures rounded or subangular and more or less oblique; the largest nearly 1 mm. in diameter, the average adult size about 0.7 mm., while many are smaller, presumably younger, ranging in size between 0.2 and 0.5 mm. Septal strize apparently wanting. Here and there a faintly raised line may be detected on the inner side of the imperforate walls, but they are too irregular in their disposition and number to be called septa. *“ The majority of compound corals included in the Favositid@ are composed of polygonal prismatic cells or corallites in juxtaposition. When, however, these cells become free, their form is cylindrical. The polygonal form of closely arranged cells is therefore explained as the natural result of crowding”; Dr. O. E. Beecher, “Symmetrical cell development in the Favositide”’ (Trans. Connecticut Academy, vol. vili, p. 215, 1891), ‘ SPONGES, GRAPTOLITES, CORALS. 85 Colaumnaria.] This species is readily distinguished from the preceding form (L. typa Winchell and Schuchert) by its thinner corallum, smaller and more unequal corallites, and the obliquity of their apertures. The last isa strongly marked feature of the species, especially near the margins of the corallum. JL. typa also occupies a lower horizon in the shales. Formation and locality.--Galena shales, near Cannon Falls, Minnesota. The type specimen is in the collection of Mr. Ulrich. Cotumnaria (?) HALLI Nicholson. PLATE G, FIGS. 14-16. 1832. Columnaria alveoluta EATON (non GOLDFUSs). Geological Text Book, p. 131, pl. 4. 1842. Columnaria Emmons. Geology of New York; Rep. Second District, p. 276, fig. 2. 1847. Columnaria alveolata HALL (non GOLDFUSS). Paleontology of New York, vol. i, p. 47, pl. 12, z figs. la—le. 1857. Columnaria alveolata BILLINGS. Canadian Naturalist and Geologist, vol. i, p, 124. figs. 9, 10. 1863. Columnaria alveolata BILLINGS. Geology of Canada, p. 139, fig. 70, and pp. 938, 954. 1875. . Columnaria alveolata NICHOLSON. Palzxontology of the Province of Ontario, pp. 8, 24. -1876. Columnaria alveolata ROMINGER. Fossil Corals of Michigan, p. 89, pl. 34, figs. 1, 2, 4. 1879. Columnaria (?) halli NICHOLSON. Paleozoic Tabulate Corals, p. 200, fig. 29, pl. 10, figs. 3, 3a. Description —‘Corallum forming large massive colonies which vary from a few inches to several feet in diameter, and which are composed of variously-sized polygonal corallites, in close contact with one another throughout their entire length. The walls of the corallites are not excessively thickened, and they are so completely amalgamated in contiguous tubes that even under the microscope the original lines of demarcation between the tubes can be made out with difficulty or not at all. The large tubes are usually from two to three lines in diameter, though occasionally con- siderably more than this ; and the smaller corallites are of all sizes. Septa marginal, in the form of obtuse longitudinal ridges which vary in number from twenty to forty, do not extend to any distance into the visceral chambers, and are not divisible into an alternating longer or short series. Tabulze strong, horizontal and complete, about half a line apart or sometimes closer. Mural pores not recognized with certainty.” “YT am disposed to doubt very strongly if the present form can be referred to Columnaria at all, and whether it is not truly a perforate coral congeneric with Nyctopora, Nicholson.” (Nicholson, op. cit., p. 200.) Columnaria alveolata Goldfuss (not Hall) and Favistella stellata Hall, are synony- mous according to Milne-Edwards and Haime, and Nicholson. The latter writer says: “It is quite certain, however, that the Trenton limestone coral just alluded to [C. alveolata of American paleontologists] is not the form described originally by Goldfuss, and carefully figured by him under the name of Columnaria alveolata (Petref. Germ., pl. xxiy, fig, 7), On the contrary, the latter is almost certainly iden- 86 THE PALEONTOLOGY OF MINNESOTA. (Columnaria: tical with the coral subsequently described by Hall under the name Favistella stellata, This is rendered the more certain by the fact that the specimens of Columnaria alveo- lata described by Goldfuss are said to come from the shores of Seneca Lake, in the state of New York, where the Lower Silurian rocks do not occur in place; so that they must have been derived from a traveled boulder. This also would harmonize with the assertion of Edwards and Haime, that Columnaria alveolata (Gold.) and Favistella stellata (Hall) are one and the same coral. , “Whilst fully believing that these two corals, as described by their original discoverers, are identical, it nevertheless remains certain that the corals now recog- nized universally in America as Columnaria alveolata and Favistella stellata are entirely distinct from one another, specifically if not generically. * * * * * Ifthe strict law of priority, with its utmost rigor, is to be carried out, then the name of Favistella stellata must be abandoned ; the coral now known by this name must be called Columnaria alveolata (Goldfuss), and the coral to which this latter title has been generally applied will have to be baptized by some quite new name.” (Nichol- son, op. cit., p. 23, 1875). ‘ In 1879, Prof. Nicholson proposed for this coral the name Columnaria 2 halli. He writes, “I have come to the conclusion, after full consideration, that the best ~ course to adopt with regard to this species, is to give it a distinct and specific name.” (op. cit., p. 201, 1879.) The colonies of C. (2?) halli occurring in Minnesota are usually small masses from an inch (25 mm.) to four and one-half inches (11.5 cm.) in diameter. In the Black River group of New York, this species often attains a large size. “There is a specimen (a portion only of an entire mass) in the state collection [New York] weighing about 1,500 pounds; the whole mass probably weighed 2,000 or 3,000 pounds.” (Hall, op. ect.) Formation and locality.—Rare near the base of the Trenton shales at Cannon Falls, Preston and St. Charles, Minnesota. In the “ Upper Buff beds” of the Trenton, in Wisconsin, and at Rockton, Illinois. Common in the Black River group at Chazy, Watertown, and elsewhere in New York; Belleville, Peter- boro, Collingwood, Ontario, Canada. In the Trenton at Dixon, [llinois; High Bridge, Kentucky, and Central Tennessee (Ulrich). Collectors.—W. H. Scotield and the writers. Mus. Reg. Nos. 5546, 7726, 7784. SPONGES, GRAPTOLITES, CORALS. 87 Streptelasma.] Section MADREPORARIA RUGOSA. Family STREPTELASMIDA#, Nicholson.* STREPTELASMA, Hall. 1847. Streptoplasma, HALL. Paleontology of New York, vol. i, p. 17. 1847. Streptelasma, HALL. Ibidem, corrections, p. 339. 1857. Streptelasma, BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 122, 1875. Streptelasma, NICHOLSON. Paleontology of Ohio, vol. ii, p. 21. 1889. Streptelasma, NICHOLSON. Manual of Paleontology, vol. i, pp. 247, tig. 127B; 278, 279, fig. 156 A, B; 280, fig. 157; 297, fig. 178 A, B. Corallum simple, turbinate or conical, probably always slightly attached. Outer wall more or less thick, produced by the lateral thickening and fusing of the outer ends of the septa one with another. Septa numerous, prominent, alternately large and small, sometimes dentated along their edges, divided into four groups by three fossulz and a more or less prominent counter septum, sometimes straight, slightly bent or strongly twisted and obscuring the fossulz in the center of the calyx. Cardinal septum short or long dividing the most prominent or dorsal fossula cen- trally, which is situated on the convex side of the corallum ; alar septa short, situated in the lateral fossule ; counter septum sometimes very prominent. “The lower part of the visceral chamber is more or less extensively filled up with stereoplasma, and the upper part of the same is crossed by irregular tabule, dissepiments being also developed in moderate numbers. The center of the visceral chamber is [sometimes] occupied by a large, irregularly reticulated or trabecular pseudocolumella, with which the inner ends of the long septa are directly connected, and which is highly characteristic of the genus.” (Nicholson, op. cit., p. 298, 1889.) Type, S. expansa Hall. Species usually adopted as the type, S. corniculum Hall. A line of development can be traced clearly in S. profundum, S. corniculum and S. rusticum. The first species makes its appearance in the Birdseye and Black River groups, is generally straight in its growth with a deep visceral cavity and has reg- ular septa. This form passes into a larger and more or less strongly curved coral- lum, S. corniculum of the Trenton and Galena groups, the visceral cavity is less deep, being more strongly filled up with stereoplasma, and has a greater number of septa which in approaching the center become twisted obscuring the lateral fossule and there forms a small pseudocolumella, In S. rusticwm of the Hudson River group, the corallum attains to two or three times the length of S. profundum, while the septa are as a rule even more numerous and more strongly twisted, with a larger pseudocolumella than in S. corniculum, the entire lower portion of the coral is filled up with stereoplasma, *Manual of Pleontology, vol. i, p. 297. 85 THE PALEONTOLOGY OF MINNESOTA. [Streptelasma. STREPTELASMA PROFUNDUM (Coni'ad ms.) Owen. PLATE G, FIGS. 17-19. 1844. Cyathophyllum profundum OwkrNn. Geological Exploration of Iowa, Wisconsin and Illinois, pl. 16. fig. 5. 1847. Streptoplasma profunda HAuu. Palwontology of New York, vol. i, p. 49. 1847. Streptelasma profunda HALL. Ibidem, pl. 12, figs. 4a-4d. 1857. Streptelasma profunda BILuLINGs. Canadian Naturalist and Geologist, vol. i, p. 123, figs. 7, 8. Original description —‘“Obliquely turbinate, often slightly curved near the base, expanding above more or less abruptly ; cell profoundly deep, extending nearly to the base of the coral ; margin of the cup reflexed ; surface scarcely marked by trans- verse ruge ; lamella from 36 to 60, strong, nearly equal on the margin, but distinctly alternating in length within ; no transverse dissepiments or celluliferous structure.” Billings probably was the first to point out that the three primary septa of Streptelasma are plainly indicated on the outside of the corallum from which the other septa branch. He says: “The mode of growth of these corals [S. corniculum and S. profundum] appears to have been as follows: At first they consisted of a mere point attached to the rock, when the cup commenced to form there were only four partitions or lamella; as it increased others were added, three of the original ones continuing to grow, and the fourth being undeveloped. In good empty specimens of S. profunda the three large primary lamellie are very conspicuous above the others on the inside of the cup, and on the outside their position is marked by three upright seams extending from the top to the bottom, and from each side of which the newer lamellw may be seen branching away.” In the Canadian specimens of this species the corallum “is very little or not at all curved,” and the same is true of Minnesota individuals occuring in the Trenton limestone and the lower portion of the shales immediately above. In Wisconsin, however, where it is quite abundant near the base of the “Upper Buff” beds in well preserved specimens, the curvature is more often as great as in S. corniculum Hall. The point of attachment in these is often well shown, but is generally smaller than in that species. S. profundum can be readily separated from 8. corniculum by its profoundly deep visceral cavity, smaller number of distinct crenulated septa which are never twisted in approaching the center and in the more sharply defined lateral fossula and greater development of the four primary septa. Billings gives the number of large and small septa in adult Canadian examples as about seventy-four, and this likewise is true for Minnesota specimens, while those from Wisconsin vary between 60 and 72, The greater variation mentioned by Hall, “lamelle from 36 to 60,” is probably due to young examples, which always have a smaller number of septa than adult speci- mens, % SPONGES, GRAPTOLITES, CORALS. 89 Streptelasma. ] Formation and locality.x—A bundant as natural casts of the visceral cavity near the top of the Tren- ton limestone at Minneapolis, St. Paul and Cannon Falls, Minnesota. In the Trenton shales it is com- mon at Minneapolis, St. Paul, Cannon Falls, Fountain, near Caledonia, and Preston, Minnesota; Decorah, Iowa. Very common near the base of the ‘* Upper Buff” beds of the Trenton in siliceous specimens at Mineral Point, Beloit and Janesville, Wisconsin ; and as natural casts at Rockton, Illinois. In the Tren- ton limestone at Dixon, Illinois; ‘‘ Glade limestone” vf Tennessee. In the Birdseye limestone at Manheim and East-Canada creek, NewYork; Canada; and in Mercer county, Kentucky. In the Black River group at Watertown and Chazy, New York; Isle la Motte; and Canada Collectors.—W. H. Scofield, H. V. Winchell, C. L. Herrick, E. O, Ulrich and the writers. Mus. Reg. Nos. 433, 664, 710, 3487-3489, 4038, 4057, 5053, 5079, 5305, 6751, 6774, 6781, 6808, 7737-7743, 7912, 7986. SrREPTELASMA (?) PARASITICUM, 7. sp. (Ulrich). Fig. 6. Fig. 6. Streptelasma ? parasiticum Ulrich, Trenton shales, St. Paul, Minnesota. a, View of the type specimen of this species, natural size ; b, several of the corallites on the opposite side of the speci- men, x3; ¢, sectional view of one of the corallites, to show depth of calyx. Corallum small, parasitically attached to bryozoa, consisting of a variable num- ber of conical cups growing in series one from the other in a manner suggesting Aulopora; each about 3.5 mm. long, and 2 mm. wide across the open calyx. The specimen which I regard as the type of the species, consists of ten corallites that have grown in a spiral manner over the two sides and one end of a fragment of Rhinidictya mutubilis Ulrich, about 12 mm. long. Of these the largest has a diameter of 3 mm., and the smallest only 1.5 mm. Where there is sufficient room for their unimpeded development the calices are circular and quite oblique, but at the upper end of the specimen, where they are more crowded, they are nearly direct and of shapes depending upon the degree in which they impinge upon each other. Outer surface marked with more or less distinct vertical ribs and fine but sharp encircling strie. Calices very deep, the corallites seeming to consist in great part of a mere shell, exhibiting on the inner side from thirty to thirty-six, faintly denticulate, septal ridges. One half of the number are exceedingly delicate and might be over- looked. I found it impossible to remove all the matrix from the calices, so I cannot say positively how the septa unite at the bottom. Fig. 3b shows all that could be made out. The generic position of this fossil is rather doubtful, yet it seems to me within the possibilities that it may be proven to be merely the young of some species of Streptelasma like the associated S. profundum, Still, the probability of such a finding 90 THE PALEONTOLOGY OF MINNESOTA. {Streptelasma. is so remote that I cannot hesitate to describe it as new, and as a matured form. Against these being young corallites I would urge (1) their nearly equal size, and (2) their crowded habit of growth. They could not have grown to larger size except by becoming detached from the supporting body, which is a supposition so unlikely that it is not to be entertained for a moment. Where the calices are in contact the appearance is decidedly suggestive of Columnaria, and, while I doubt it, this resemblance may really indicate true relation- ship. For the present it seems to me the species may well be arranged as above under Streptelasma near S. profundum. There it can remain till we learn more of its characters, or until the genus Streptelasma is redefined and strictly characterized. And right here I wish to say that no genus of paleozoic corals is less understood and more in need of revision than Streptelasma. -As now used it is made to include some very diverse types. | Formation and locality.—Rare in the middle division of the Trenton shales at St. Paul, Minnesota. Another specimen, consisting of six corallites, of the same or a closely related species, was collected by me from the Trenton limestone at Minneapolis. Now in my collection. STREPTELASMA coRNIcULUM Hall. PLATE G, FIGS. 20, 21. 1847. Streptoplasma corniculum HALL. Paleontology of New York, vol. i, p. 69. 1847. Streptelasma corniculum HALL. Ibidem, pl. 25, figs. la—le. 1847. Streptoplasma crassa HALL. Ibidem, p. 70. 1847. Streptelasma crassa HALL. Ibidem, pl. 25, figs. 2a—2c. 1847. Streptoplasma multilamellosa HALL. Ibidem, p. 70. 1847. Streptelasma multilamellosa HALL. Ibidem, pl. 25, figs. 3a—3e. 1847. Streptoplasma parvula HALL. Ibidem, p. 71. 1847. Streptelasma parvula HALL. Ibidem, pl. 25, figs. 4a—4e. 1857. Streptelasma corniculum BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 122, figs. 3 * and 4, on p. 121. 1863. Petraia corniculum BILLINes. Geology of Canada, p. 156, fig. 118, and p. 938. 1875. Streptelasma corniculum NICHOLSON. Paleontology of Ontario, p. 12, (p. 26 partim). Original description.—* Turbinate, curved near the base, which terminates in an acute point, somewhat rapidly expanding above; cup profound; lamelle about sixty ; surface marked by strong longitudinal lines indicating the lamell, which are crossed by fine concentric wrinkled lines. “Length varying from three-fourths to one and a half inches.” Corallum conical, more or less curved, greatest length observed 45 mm., with a diameter of 27 mm.; slightly attached. Exterior exhibiting longitudinal lines cor- responding with the larger septa within, those on the dorsal side converging to the cardinal and alar septa; rarely smooth and commonly with folds of growth. Calyx more or less deep with three fossule, the cardinal one most prominent placed on the dorsal or convex side of the corallum, with the others disposed laterally. Septa SPONGES, GRAPTOLITES, CORALS. 9] Streptelasma,] alternately large and small, slightly dentate, from 45 to 60 of the former in adult examples, while the youngest specimens observed have 30, Cardinal and counter septa long and prominent, alar septa short ; between these primary septa the others are arranged in bundles, the large ones uniting at their inner ends, and are commonly twisted (rarely straight) forming a small pseudocolumella. Lower part of the vis- ceral chamber somewhat filled up with stereoplasma. ‘T'abule and dissepiments remote and very irregular. This species can be readily separated from S. profundum, by the greater curva- ture of the corallum, shallower visceral cavity and more numerous septa, which, on approaching the center of the calyx become more or less twisted. The last named feature never occurs in S. profundum. This common coral is more or less abundant at all exposures of the Galena shales throughout Minnesota. Specimens vary from 15 to 45 mm. in length. The large and small septa vary from 60 to 120. Since so great a variation in the number of septa obtains in this species, it is advisable to consider as synonymous with it, S. crassa, S. multilamellosa and S. parvula Hall. A similar conclusion was reached by Billings in 1863 and by Nicholson in 1875. Several immature individuals of this species have been found growing on Rhinidictya, and occasionally an adult specimen will show traces near the base of the corallum of its former attachment to some bryozoan. That species of this genus are attached to foreign bodies, at least during their earlier growth, is almost certain. As the point of union is very small, it is also quite probable that the individuals, on reaching maturity, became broken off by the weight of the corallum. Formation and locality.—Common in the Galena shales at many localities in Goodhue, Olmsted and Fillmore counties, Minnesota; Decorah, lowa; Oshkosh, Wisconsin. It is also commonin the Trenton limestone at Middleville, Trenton Falls, and elsewhere in New York: Montreal, Peterboro, and Ottawa, Canada. Collectors.—E. O. Ulrich, W. H. Scofield and the writers. Mus. Reg. Nos. 162, 207, 318, 364, 5840, 6750, 7744-7751. 92 THE PALEONTOLOGY OF MINNESOTA. [Streptelasma. STREPTELASMA BREVE 1. sp. (Ulrich). Fig. 7, Streptelasma breve Ulrich, Galena limestone, near Fountain, Minnesota. a, an average speci- men, natural size; 6, an unusually straight example; c, the flattened but entire calyx of another specimen ; d, represents the greater part of the calyx of a fourth example, x 2, showing the central union and arrangement of the septa and fovex in a very clear manner. Corallum free, simple, conical, small, curved, expanding very rapidly, the width greater than the hight. An average specimen is about 11 mm. high and 16 mm. wide across the cup. In a small specimen the measurements are, respectively, 7 and 11 mm. Surface marked with fine encircling lines and stronger annulations of growth ; occasionally also with delicate vertical ribs. The latter seem, however, to be restricted to the lower half of the corallum. * Calyx deeply concave, the bottom extending to a point a little beneath the middle of the hight. Septa large and small, the latter shown only in the extreme outer part of complete calices, the ormer extending to the center where they unite into four bundles of from six to eight in each. Principal septum straight, sometimes stronger than the others, extending to the center through a well marked fovea. The septa on each side of it arranged in a pinnate manner, uniting centrally. Lateral fovee narrow, but gen- erally recognizable. Opposite septum forming the central one of usually fifteen septa that are radially arranged in the half of the calyx on the shorter or concave side of the corallum. Asa rule it is distinguished by its greater strength and prom- inence. Lateral septa inconspicuous, shorter than the others. Total number of septa in a specimen of the average size about sixty-four, of which thirty-two are large and long, while an equal number belong to the intermediate rudimentary set. All of them seem to have been obscurely dentate, and but little elevated, so that they are to be termed ridge-shaped rather than lamellate. At the center of the calyx the septa inosculate, forming a limited number of cells bounded by spinulose walls. As shown in fig, 2d, the condition described is scarcely to be called a twist- ing of the septa, Internal structure unknown, SPONGES, GRAPTOLITES, CORALS. 93 Streptelasma. ] This spe@ies seems to be near S. corniculum Hall, byt is readily distinguished by its smaller size, more rapidly expanding corallum, more distinct fovew, and less twisted as well as less laminar septa. S. profundwm Conrad (Hall) is straighter, has a deeper calyx, and is entirely without the central twisting or inosculation of the septa. Formation and locality.—Rather rare at the top of the Trenton limestone, near Fountain, Minnesota. Ten specimens collected by the author are now in his cabinet. STREPTELASMA RuSTICUM Billings. 5 PLATE G, FIGS. 22, 23 1851. Streptelasma corniculum EDWARDS and HAImME (non Hall). Monograph Poly. Foss. des Terr. Pal., pl. 7, fig. 4. 1858. Petraia rustica BILLINGS. Geological Survey of Canada; Report of Progress for 1857, p. 168. 1875. Streptelasma corniculum NICHOLSON (non Hall). Paleontology of Ohio, vol. ii, p. 208. 1875. Streptelasma corniculum (partim) NICHOLSON. Paleontology of the Province of Ontario, p. 26, 1882. Streptelasma corniculum HALL. Eleventh Report State Geologist of Indiana, p. 376, pl. 51. figs. 2-4. 1889. Streptelasma rusticum MILLER. North American Geology and Paleontology, p. 205. 1889. Streptelasma corniculum NICHOLSON. Manual of Paleontology, vol. i, p. 247, fig. 127B; p. 278, 279, figs. 156A, B; p. 280, fig. 157; p. 297, figs. 178a, 178b. Original description.“ Straight or slightly curved, covered with astrong epitheca, which is more or less annulated with broad shallow undulations ; radiating septa about one hundred or usually a little more ; much confused in the center, where they form a vesicular mass ; every alternate septum much smaller thau the others, only half of the whole number reaching the center. Length from two inches and a half to three inches and a half. Diameter of cup one inch to one inch and a half; depth of cup half an inch or somewhat more.” This species attains a larger size than S. corniculum Hall, with which it is usually identified, and differs from it in having the septa more strongly twisted and coarser in approaching the center of the calyx, where they form a vesicular mass or pseudo- columella. This central twisting of the septa is not so pronounced in Minnesota specimens as it is in individuals from Richmond, Indiana. A large series of speci- mens will exhibit considerable variation in the extent of the central vesicular mass, and though it is usually of much coarser construction in the form described by Billings, it cannot be denied that the two species are very closely related. Formation and locality.—In the Hudson River group near Granger, and at Spring Valley, Minnesota; Graf, Iowa; Richmond, Indiana; Oxford and Dayton, Ohio. Snake island, lake St. John, and Manitou- waning, Georgian bay, Canada. Collectors.—W. H. Schofield, E. O. Ulrich, and the writers. Mus. Reg. Nos. 7753, 7754. 94 THE PALEONTOLOGY OF MINNESOTA. [Protarea. Section MADREPORARIA PERFORATA. Family PORITIDAS. Prorar@a vetusta Hall, sp. PLATE G, FIGS. 24, 25. 1847. Porites? vetusta HALL. Paleontology of New York, vol. i, p. 71, pl. 25, fig. 5a, 5b. 1850. Zoarium adnate, branching dichotomously, or inosculating, in the latter case forming an irregular large-meshed network. Branches narrow, generally with two or three, rarely four or five, alternating series of cells. Zocecia subpyriform, or obovate, not wholly immersed, generally appearing as bulbous swellings on the sur- face of the zoarium. Apertures subterminal, contracted, circular, slightly oblique, about 0.09 mm. in diameter, with a slight peristome. About five or six cells in 3.0 mm. Compared with Proboscina frondosa (plate I, fig. 28) and P. auloporoidea (both Nicholson, sp.), two Hudson River forms, this species is distinguished by its shorter and more bulbous zocecia, their shape being more like those of Stomatopora inflata and Berenicea minnesotensis. The resemblance to the last is so marked that I would not be surprised if coming discoveries prove P. tumulosa directly descended from it. Formation and locality.—Rare in the upper third of the Trenton shales at St. Paul; more abundant in the same beds near Cannon Falls, Minnesota. Mus. Reg. Nos. 7620, 8047, 8101. Progosorna FRONDOSA Nicholson. PLATE I, FIG. 28. Alecto frondosa NICHOLSON, 1875. Pal. Ohio, vol. ii, p. 266. Proboscina frondosa ULRICH, 1889. Contri. to the Micro-Pal. of Canada, pt. ii, p. 28. A figure, taken from an excellently preserved example of this species, is intro- duced for the better understanding of, and comparison with, Minnesota Cyclostomata. This specimen is from the hill quarries at Cincinnati, Ohio, but the species also occurs in the upper beds of the formation at many localities in Ohio, Kentucky and Indiana, at Nashville, Tennessee, Wilmington and Savannah in Illinois, and at Stony Moun- 120 THE PALEONTOLOGY OF MINNESOTA. [Berenicea. tain, Manitoba, My belief that it will yet be found at Spring Valley, Minnesota, and other points in the southern part of the state, where equivalent beds are exposed, is therefore within the bounds of probability. Mus. Reg. No. 8102. Genus BERENICEA, Lamouroux. Berenicea (part.), LAMOUROUX, 1821. Exp. meth. des genres de pol., p. 80. Rosacilla, ¥'. A. ROEMER, 1840, Verst. des norddeutsch. Kreidegeb., p. 19. Berenicea, d’ORBIGNY, 1852. Pal. Fr. terr. cret., t. v, p. 858. J. HArtme, 1854, Bry de la form. Jurass., p.19. Utricu, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p 194, and 1890, Geol Sur. Ill., vol. viii, p. 368. Diastopora, @Orsiany, 1850, and Busk and other English authors. (Not Lamouroux.) Diastopora (part.), HINcKs, VINE and others, Saganella, HALL, 1852. Pal. N. Y., vol. ii, p. 172. Diastoporella, VINE, 1883. Brit. Assoc. Rep. Foss. Pol., iii; and Proc. Yorks. Geol. Soc., n. s., vol. ix, pt. li, p. 190. . Zoaria incrusting, forming circular or irregular patches. Individual zocecia as in Stomatopera and Proboscina, but contiguously arranged in more or less regular spreading series, Type: B. diluviana Lamouroux. For remarks relating to this genus see under Stomatopora. & /p BERENICEA MINNESOTENSIS Ulvich. PLATE I, FIGS. 25, 27 and 29; PLATE II, FIG. 1. Berenicea minnesotensis ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Sur. Minn., p. 58. Zoarium forming exceedingly thin, irregular crusts upon foreign bodies. The crust may be entire, with irregularly distributed and unequal non-celluliferous spots, or, especially at the edges of large expansions, it may throw off broad branches and include a few open spaces. In one example, provisionally referred here, the latter are so large and conspicuous that the zoarium may well be described as consisting of wide, irregularly inosculating branches.* Ordinarily the crust is nearly entire, and the non-celluliferous spaces, which, like the rest of the surface between the zoccial apertures, are marked with obscure transverse lines or wrinkles, constitute a con- spicuous feature. Zocecia more or less immersed, in the latter condition appearing as subelliptical convex spaces, about 0.2 mm. wide, with an oblique circular aperture, 0.13 mm. in diameter, at their upper ends. In such examples (see fig. 29) the aper- ture is scarcely produced, but in others, more matured, it is prominent, while all the remainder of the cell is completely immersed. The arrangement of the zoecia is, *Perhaps this specimen is to be cousidered as indicating a departure that later on resulted in Proboscina tumulosa of this work. BRYOZOA. 121 Diastoporina. ] on the whole, inclined to be irregular, though fairly regular longitudinal series, and sometimes diagonally intersecting rows can generally be made out. The average number in 2 mm. is five or six. Compared with B. primitiva Ulrich, from the Hudson River group of Ohio, this species is distinguished by its larger and less tubular zocecia, the interstitial wrinkles, and the non-celluliferous spaces. B. vesiculosa Ulrich, from the Utica shales horizon at Cincinnati, is a nearer relative, but also has smaller zocecia, with the apertures less prominent. In most respects the position of the Minnesota species is inter- mediate between the two Ohio species. ‘Formation and locality.—Not uncommon in the lower and middle beds of the Trenton shales, at Minneapolis and St. Paul, Minnesota. Mus. Reg. No. 5925. Genus DIASTOPORINA, Ulrich. . Diastoporina, Ulrich, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 177. Zoarium bifoliate, in general resembling Diastopora (Lamouroux, not Busk). Zowcia subtubular, prostrate, immersed ; apertures constricted, subcircular, not prominent. Interspaces finely punctate and striated longitudinally. As only one species is known, it is difficult, if, indeed, it is not impossible in all such cases, to determine the really essential characters of the genus. The striation of the interspaces is a peculiar feature and the chief ground for separating the species from Diastopora, a genus so far not known in strata older than Jurassic. The Minnesota species, however, presents many points of agreement with species of that well known genus, and it may yet be shown that it represents merely an early type of same. This resemblance or possible relationship is paralleled in Mitoclema, Ulrich, and Entalophora, Lamouroux ; Diploclema, Ulrich and Bidiastopora, d’Orbigny; Protocrisina, Ulrich, and Crisina, W’Orbigny; and Scenellpora, Ulrich, and Defrancia, Bronn, aud Discocavea, d’Orbigny. In each case the first is founded upon lower paleozoic species, while none of the genera with which they compare are as yet known in rocks earlier than Jurassic. With the exception of Entalophora (?Mito clema) one or more species of which occur in the Devonian at the Falls of the Ohio, and in New York (Clonopora, Hall, 1887, Pal. N. Y., vol. vi), none of these cyclostoma- tous genera are known to have had an existence in Devonian and Carboniferous times. Precisely the same is true of Stomatopora, Proboscina, and Berenicea.* But * Since writing the above, a paper has been received from the Canadian Geological Survey, in which Prof. J. F. Whit- *eaves describes one species each of Stomatopora and Proboscina, from the Devonian rocks of the far north. At my request, Prof. Whiteaves kindly sentme the types of the two species. These were carefully examined by me, with the result, that I still hold that we have no positive evidence of the existence of these genera in Devonian deposits. The first is unquestionably very closely related to Rhopalonaria botellus Vine, and not a Stomotopora. The other may be a Proboscina, but it isso different from any type of that genus known to me that I am obliged to view its relations as highly problematical. 122 THE PALEONTOLOGY OF MINNESOTA. | Distribution. in these cases the Lower and Upper Silurian species are so nearly like the Secondary, Tertiary, and recent forms of the genera, that a generic separation has so far seemed impracticable. And yet, considering their apparent absence in the Devonian and Carboniferous deposits, would we not be justified in denying the lineal descent of the recent forms from the early paleozoic species ? However, questions of this kind can- not be considered as they deserve in the space here at my disposal, and, as they are also a little out of place in a publication of this kind, they will be merely touched upon, leaving their real discussion for some more fitting occasion. DIASTOPORINA FLABELLATA Ulrich. PLATE II, FIGS. 2 AND 3. Diastoporina flabellata ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 176. Zoarium small, arising from an attached basal expansion into thin flabellate fronds. The largest and only complete example seen is 5.5 mm. wide. Surface with obscure concentric wrinkles, and fine interrupted striations arranged parallel with the direction of the zocecia. Under a high power of magnification the latter appear as delicate lines separating rows of exceedingly minute pores. Zocecia rather scattering, in young examples partly exposed, appearing as convex oval spaces with a small oblique aperture, about 0.05 mm. in diameter and but little, if at all, elevated at the distal extremity. In some fragments of seemingly older examples the entire cell is immersed, leaving only the aperture, which, in these cases, is nearly direct and subtubular, to project over the nearly even surface. Their arrangement is often quite irregular, particularly in the vicinity of certain small non-celluliferous spots, but where rows are to be made out, about six or seven apertures occur in 2 mm. This is the only bifoliate cyclostomatus bryozoan known to me in paleozoic rocks. Formation and locality—Rare in the Galena shales near Cannon Falls and at St. Paul, Minnesota. At the first locality it is associated with a very interesting fauna, consisting principally of Ostracoda and minute bryozoans, among the latter species of Nematopora, Helopora and Arthroclema. Genus MITOCLEMA, Ulrich. Mitoclema, ULRIcH, 1882. Jour. Cin. Soc. Nat. Hist., vol. v, p. 150; and 1890, Geol. Sur. Ill., vol. viii, pp. 3386 and 369. Comp. Clonopora, HALL, 1886. Pal. N. Y., vol. vi, p. 25; also, abstract Trans. Albany Inst., vol. x- p- 20, 1881. Comp. Entalophora, LAMOUROUX, 1821. Exp. meth. des genres de pol., p. 81. Zoaria ramose, slender, subcireular in cross-section. Zoccia tubular, long, pris- matic and thin-walled in the axial region, gradually diverging in all directions from BRYOZOA. 129 Distribution.] an imaginary axis to the surface where they bend outward abruptly, often becoming free and much produced. Apertures circular, sometimes scattering, usually arranged in regular transverse or subspiral series. Type: M. cinctosum Ulrich, Chazy (perhaps lower Birdseye) limestone of Ken- tucky. Fuller investigations and comparisons with typical and authentic examples of Entalophora and Clonopora are necessary before we may be said to be in a position to decide peimanently the merits of this genus. Hntalophora, as now understood by Hincks and Waters, seems to me to be too comprehensive and might be, with advant- age to classification, divided into at least two groups of generic rank, and it is not at all improbable that Mitoclema stands upon unoccupied ground. In the mean time no harm can result from the use of the name for these early paleozoic species. Mrroctema(?) mMunpuLum Ulrich. PLATE II, FIGS, 4-6. J Mitoclema ? mundulum ULRIcH, 1890. Jour. Cin. Soc. Nat.Hist., vol. xii, p. 177. Zoarium ramose, yery small, the branches cylindrical, 0.5 or 0.6 mm. in diameter, with faint transverse striz or wrinkles over the spaces between the zowcial apertures. The latter are drawn out tube-like, about 0.15 mm. in diameter, and project strongly upward and outward from the surface of the small stems. Their arrangement is in rapidly ascending spiral series, with four or five in 2mm. As near as can be deter- mined from the material at hand, the zowcial tubes diverge equally to all sides of the branches from an imaginary axis. Owing to the absence of specimens suitable for slicing the internal characters of this species have not been determined. The generic position is therefore somewhat questionable, since it may prove to have the structure of Diploclema Ulrich (Geol. Sur. Ill., vol. viii, p. 368), founded upon D. trentonense Ulrich, a similar form occur- ring in the Trenton limestone of New York. In Diploclema the branches are slightly compressed, and the zocecial apertures somewhat constricted and less prominent.* Formation and locality.—Associated with the preceding in the topmost beds of the Trenton shales, at Cannon Falls, Minnesota. Mus. Reg. No. 8103. *In his paper on Wenlock shales Bryozoa Mr. Vine has described several similar species which he originally referred to Spiropora and later to Entalophora Of these S. regularis is an unquestionable Diploclema and closely allied to our Niagara D. sparsum Hall, sp. The others I have not had an opportunity of examining. 124 THE PALEONTOLOGY OF MINNESOTA. {[Rhinidictya. Suborder CRYPTOSTOMATA, Vine. Family RHINIDICTYONIDAs, n. fam. Stictoporide, ULRIcH, 1890. Geol. Sury. Ill., vol. viii, p. 388. Stictoporide (part.), ULRicH, 1882. Jour. Cin. Soc. Nat. Hist., vol. v, p. 152. This name is proposed instead of Stictoporide, for the reason that the type genus is not, as I have heretofore held, properly expressed by the term Stictopora. Since Hall, the author of that name, and others, insist that S. elegantula is the type of Stic- topora, it follows that the genus and family as described by me (loc. cit.) cannot stand. In my Illinois work, namely, I had taken the stand that S. fenestrata is to be regarded as the type, and as that species is unquestionably congeneric with Lhinidictya, Ulrich, (Jour. Cin. Soe. Nat. Hist., vol. v, p. 152), the latter was reduced to synonomy. Though the minute internal and external details of structure of S. elegantula have not yet been made public, enough is known of it to prove conclusively that it represents a genus to which S. fenestrata has no claim. This being the case, Rhinidictya will stand and inelude fenestrata.* Genus RHINIDICTYA, Ulrich. Stictopora (part.), HALL, 1847. Pal. N. Y., vol. i, p. 73. Stictopora, ULRicH, 1890. Geol. Surv. Ill., vol. viii, p. 388. Rhinidictya, ULRicH, 1882. Jour. Cin. Soc. Nat. Hist., vol. v, p. 152;.HALL, 1887, Pal. N. Y., vol. vi, p. 20. “Zoaria composed of narrow, compressed, dichotomously divided branches, with the margins sharp, straight, and essentially parallel; attached to foreign bodies by a continuous expanded base. Zocecial apertures subcircular or elliptical, arranged alternately in longitudinal series between slightly elevated, straight or flexuous ridges, carrying a crowded row of small blunt spines. Space immediately surrounding aper- tures sloping up to summits of ridges.” (Geol. Surv. IIL, vol. viii, p. 388.) Type: R. nicholsoni Ulrich, Birdseye Limestone, Kentucky. This genus finds its strongest development numerically, both as regards species and individuals, in the rocks of the Trenton formation. The Minnesota shales of this group are especially rich in specimens, and so far as species are concerned, there is no other section of the country from which as many are known. Unfortunately, however, the various forms of the genus are not by any means easily distinguished from each other. It is true also that of those species which have a wide geographi- cal range, as for instance from Minnesota to Kentucky and Tennessee, or to New oy * Wor objeotions to the use of Sulcopora, d’Orb., instead of Rhinidictya, see Geol. Surv. IIL, vol. viii, pp. 683 and 687. BRYOZOA. 125 Rhinidictya.] York and Canada, the specimens at each of these localities are marked by individual peculiarities, causing their identification to be, in some cases at least, unsatisfactory and generally rather difficult. Nothing less than monographical work can do the genus justice. Manifestly, even if possible in the present state of our knowledge, such work would be out of place here. I shall therefore largely restrict my remarks to the Minnesota forms, while those occurring in other sections of the country will be mentioned incidentally only, and chiefly when comparisons are desirable. Rurnrwrerya murasiis Ulrich. PLATE VI, FIGS. 1-6, 12-18; PLATE VII, FIGS. 10-23, and 25-28; and PLATE VIII, FIGS. 1-3. Stictopora mutabilis (part.) ULRicH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 66. Stictopora mutabilis, var. minor ULRicH. Ibidem, p. 67. Zoarium a branching bifoliate stipe, varying considerably in width and superfi- cial aspect. Typical form :—In the commonest or typical form, the branches vary in width from 2.3 mm. to 3.2 mm., and in thickness from 0.7 mm. to 1.9 mm.; they divide dichotomously at intervals varying from 7 to 16 mm.,-but on an average a bifurca- tion takes place every 10 to 12 mm.; edges generally sharp, but with age become blunter as the stipes increase in thickness; non-celluliferous margins very scant, often practically wanting. Zocecia arranged in from ten to eighteen rows ; the usual number is fourteen or fifteen, but just beneath a bifurcation it generally exceeds twenty. Between the rows are straight longitudinal ridges, angular and crowned with a single series of small granules in well preserved young and average examples, _ thicker, rounded, and with stronger and more numerous granules in old examples (see plate VII, fig. 10). In young examples again the spaces between the ends of the apertures are slightly depressed, causing them (the apertures) to appear as openings in the bottom of shallow channels. In such specimens (see plate VII, fig. 15) the interspaces are comparatively thin and the zoccial apertures correspondingly large, the long diameter of the latter being about 0.20 mm., and the short or transverse diameter about 0.12 mm. With age the transverse diameter may be reduced to less than 0.5 mm., while the channelled appearance becomes obsolete in the general thick- ening of the interspaces. In a few fragments, apparently representing the condition of extreme age, the zoccial apertures are scarcely recognizable, the entire surface appearing as simply granulo-striate. In most cases the zocecial apertures in one or more of the marginal rows are directed upward and outward. Measuring trans- versely, about eleven of the central rows in 2 mm, (extremes ten and twelve); longi- 126 THE PALEONTOLOGY OF MINNESOTA. [Rhinidictya. tudinally, about seventeen zocecia in5 mm. Except in a variety to be considered presently, the zoccial apertures always appear as direct. Vertical sections (plate VI, figs. 3 and 5) show that the zocecial tubes, in their course from the basal (median) plate to the superficial aperture, form an angle of about 50 degrees with the surface. In the primitive portion of the zoccia (7. e. that part which lies on each side close to the median lamin) the posterior side curves out- ward and forward so as to form a curve about equaling one-fourth of a circle. The anterior extremity of the curve terminates abruptly at the primitive aperture ; from this point to the surface of the zoarium, or in what has been described as the “ vesti- bular portion of the zocecium,” the course of the wall is nearly straight. In a few species of this genus (e. g. R. fidelis and R. minima) the junction between the “ves- tibule” and the curved posterior side of the “primitive cell”, is prolonged into a short septum that I have designated as the “superior hemiseptum.” In R. mutabilis, however, this septum is but little, if at all, developed, the junction being merely an- gular. When the section shows the transverse interspaces (this is often the case because of the great thickness of the interspaces in the vestibular region) they will be seen to exhibit interrupted dark vertical lines. These represent the tubular internal extensions of the minute granulations noticed at the surface. Stages in the growth of the zoarium may also be determinable. These are marked by dark lines, sharpest in the inner portions of the zoarium. In transverse sections the chief point of interest is the row of minute tubuli that exists between the two parts of the duplex mesial lamina. (See plate VI, fig. 6.) Tangential sections present a variety of appearances depending (1) upon the age of the fragments sectioned, and (2) the depth beneath the surface represented in the section. Using an old example the section may be made, with judicious manipula- tion, to show all the conditions through which the zoarium has passed, from the “ beginning of the zocecia on the mesial laminz to their mouths. Taking such a sec- tion, which, to be satisfactory, should not be less than 10 to 15 mm. long, the follow ing features are likely to result: Starting with the mesial lamin, which will be recognized as a faintly dark space, the first character worthy of notice are the “median tubuli.” These are represented by very delicate parallel lines, longitudinal in the central third of the zoarium, but gradually diverging or curving toward its edges in the lateral thirds. Though not yet clearly demonstrated in this species, I neverthe- less assume it to be a fact (because of observations in other forms possessing such tubuli) that the “mesial tubuli” connected with the minute tubes between the walls of the zocecia, the surface extensions of which have been described as granules. (See plate VI, fig. 18.) Just above the mesial lamine the section presents the basal or : BRYOZOA. 127 Rhinidictya.] priniitive portion of the zowcia as sharply defined, thin-walled, oblong-quadrate spaces, the end walls of which, while approximately at right angles with the long- itudinal lines at the center of the zoarium, gradually assume an oblique upward direc- tion toward the sides. (Compare plate VI, fig. 13.) The next condition is when the anterior wall or side of the zocecium becomes convex, while the posterior side begins to extend over the cell till at last the oval aperture is formed. Now the anterior and posterior walls are no longer recognizable in the section, but the division between the longitudinal walls is clearly marked by a dark line, that, when the preservation of the specimen is sufficiently favorable, will be noticed to consist of a connected series of minute tubuli. Besides these, an occasional dark spot or tubulum may be noticed in the end spaces. Most of the stages so far described are shown in fig. 13, on plate VI, and all further phases are to be classed as old conditions. They consist principally of an increase in the number of minute interstitial tubuli. (See plate VI, figs. 1 and 4.) The above description does not include two forms that deserve recognition as varieties. Their peculiarities are not sufficiently constant to entitle them to the rank of species. In my preliminary report on the Minnesota Bryozoa (loc. cit.) another form of the species was separated as var. minor. The better and much more complete material since studied proves, however, that the specimens so desig- nated are merely young examples and therefore not deserving of a distinct name. Var. Magor Ulrich. The zoarium in this variety is more robust, the branches being wider, in some cases attaining a width of over 8 mm.; usually the thickness is also greater, but thin examples are not uncommon. Perhaps the chief peculiarity of the variety is found in certain grano-striate or smooth spots, which occur at rather irregular intervals along the center of the branches. The internal structure agrees in all essential respects with that of the typical form of the species, the only feature not seen in the latter being the solid macule. Mus. Reg. No. 5940. Var. SENILIS, 7. var. PLATE VI, FIGS. 2 and 3; PLAT® VII, FIGS. 16 and 1%. In this rather rare form the general appearance of the zoarium is like that. of well developed examples of the typical variety. On comparison, however, it is found that the non-celluliferous margin is unusually wide and sharply defined. Connected with this are certain narrow, irregular or subelliptical, depressed spaces just within the axes of bifurcation. A more important peculiarity is presented by the zocecial apertures. These, generally, instead of being placed in longitudinal furrows](as 128 THE PALEONTOLOGY OF MINNESOTA. [Rhinidictya. is usual in the genus), are oblique and inclosed by a strongly elevated peristome, highest at the posterior side. They manifest further a tendency to arrangement in transverse or diagonal rows. The result is quite unlike what is to be expected in Rhinidictya, and reminds one more of certain species of Cystodictya. Thin sections, however, demonstrate that this is merely a case of superficial resemblance and not of true relationship. On the contrary these prove, as is already clearly enough shown at the growing extremities of the branches, that we are dealing with a true Rhinidictya with affinities to Rk. mutabilis too close to admit of even specific distine- tion. Indeed, it is not improbable that the variety represents merely an unusual condition of senility. Still, the interior, as exhibited in the sections at hand, has one feature that may be accepted as corroborating my present estimation of the form. * Plate VI, fig. 2, represents a portion of a tangential section showing, besides one of the solid axillary macule, that the minute interstitial tubuli are exceedingly numerous, there being often three longitudinal rows between adjoining zocecia. Figure 3 of the same plate presents a portion of a vertical section of the same speci- men. This compares very nearly with figs.5 and 12 (pl. VI) prepared from old exam- ples of the typical form. The absence of horizontal lines in the lower part of the walls may be the result of imperfect preservation. This species, especially in its typical form, is to be regarded as closely allied to R. nicholsoni Ulrich (Jour. Cin. Soc. Nat. Hist., vol. v. p. 170, pl. vin, figs. 6, 6a, 6b; 1882). Without taking into account certain slight though recognizable internal dif- ferences, that species is distinguished by its narrower, more strictly parallel, and less frequently bifurcating branches, the obliquity of its zocecial apertures, and the lesser elevation and rigidity of the transverse interspaces. A nearer congener, perhaps, is the R. basalis (Stictopora basalis Ulrich, op. cit., p. 169, plate viii, figs. 4 and 4a), but the very frequent bifurcation of the zoarium characterizing that species serves to distinguish them at a glance.* For comparisons with R. trentonensis, R. fidelis, and other species described in this report see under descriptions of each. Formation and locality.—The typical form is extremely abundant in the middle and lower beds of the Trenton shales about Minneapolis and St. Paul, Minnesota. It occurs in these beds, but much less abundantly, also"at Cannon Falls, Lanesboro, Fountain, Preston and other localities in the southern part of the state, and at Decorah, Iowa. The var. mojor is fairly abundant at the three localities first named, but the Cannon Falls specimens are less robust than usual. From the Galena shales at Cannon Falls, I have identified with the species something over forty fragments. In these, however, the zowcial apertures are more oblique than usual. Respecting the Kentucky form, which I have heretofore referred to this species (14th Ann. Rep. Geol. Nat. Hist. Sur. Minn., p. 67, 1886), I prefer to await further investigations before expressing a conclusive opinion. This course seems the wisest also with respect to similiar forms from the Trenton rocks of Illinois, Tennessee, New York, Vermont and Canada. Mus. Reg. Nos. 5938, 5939, 5941, 5956, 5957, 7597, 7599, 7606, 7621, 7663. *A very good illustration of the necessity of thin sections for the determination of the generic relations of these bifoli- ate Bryozoa is furnished by my 1882 work on them in the publication cited. Had they been prepared of all the species therein defined. I would not have fallen into errors that now appear only too obvious. There I placed, for instance, Pachydictya acuta Hall, sp., Cystodictya gilberti Meek, sp., and Rhinidictya basalis under Stictopora, while Rhinidictya was founded, correctly enough, upon both external and internal peculiarities of R. nicholsoni. With sections I could scarcely have failed in detér- 2 mining the true position of these four species, BRYOZOA. 129 Rhinidictya ] Ruwinipictya PAUPERA Ulrich. PLATE V, FIGS. 19-21. Stictopora paupera (part.) ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Sury. Minn., p. 69. Zoarium usually less than 30 mm. high, consisting of narrow parallel-sided branches, dividing dichotomously at intervals of from 4.0 to 12 mm. Near the base the intervals are usually less than 6.0 mm., but further up the prevailing distance between bifurcations is about 8.0 or 9.0 mm. The width of the branches is fairly constant, deviating but little either way from 1.3mm. Their thickness has not been noticed to exceed 0.5 mm. Zocecia with nearly direct oblong apertures, their shapes varying with age from subquadrangular to elliptical. Interspaces rather narrow, or of moderate thickness. Zocecial apertures usually in ten or eleven rows, but eight or nine and twelve rows often occur just after and before bifurcations. The central five or six rows are arranged between raised longitudinal lines, minutely granulose when perfect, while the two or three rows on each side are, besides being slightly larger than usual, directed obliquely outward. Five of the central rows in 0.7 or 0.8 mm ; measuring lengthwise along same eighteen or nineteen apertures in 5.0 mm. Internal structure very much as in young examples of #. mutabilis Ulrich. In the above diagnosis I have restricted my observations to the Minnesota form occurring in the upper division of the Trenton shales at St. Paul and Cannon Falls. This form should be regarded as the type of the species, and, pending further investi- gations, the wisest course seems to be to restrict the use of the name to it. The Kentucky and Tennessee form, occurring in the shaly upper member of the Trenton group in those states, which I have referred to this species (loc. cit.), is now regarded as distinct and next described as R. neglecta. I have two specimens from the “ Phyl- loporina beds” at St. Paul that are exceedingly like, if not identical with the latter, but so far it has not been found in the shales above these beds, nor in the Galena limestone division of the Trenton in Minnesota. But several examples collected from the Galena shales at localities near Cannon Falls, seem to be identical with the Canadian form referred to Rk. paupera in 1886. Formation and locality.—Common in the middle third of the Trenton shales at Minneapolis and other localities in the state, and Decorah, Iowa. Perhaps, also, in the lower third of the shales, but rare in these and smaller than usual. A single example collected by Mr. Charles Schuchert from the ‘*‘ Lower Blue beds” near Beloit, Wisconsin, seems to belong to this species. Mus. Reg. Nos. 5929, 7558 and 7597. BRYOZOA. 171 Fscharopora.] EscHAROPORA CONFLUENS nN, sp. PLATE XIII, FIGS. 1-12. Zoarium branching, the smallest seen less than 25 mm. high, with the branches averaging about 2.5 mm. in width; the largest fragments indicate a hight of from 80 to 120 mm., and in these the width of the branches varies from 4to8 mm. The two surfaces of the branches are generally obtusely ridge-shaped, and in the largest a row of monticules, or simply clusters of large cells, occurs on the summit of the ridge. Edges thin and sharp, commonly with a coarsely striated or pitted narrow border. Through all stages, though less distinct in the oldest, the zocecial apertures are narrow and appear to be drawn out at the ends so as to connect by means of a narrow channel. This confluent character of the zocecial apertures is better shown and more regular in the central rows, where they are also_narrower and on the whole considerably smaller than towardthe margins. (See fig. 5.) In the central rows, ten in 5 mm. lengthwise ; eighteen or nineteen in 5 mm. diagonally, and five and one-half in 1 mm., and ten in 2 mm. transversely ; of longitudinal rows there are nineteen or twenty in 2 mm. Tangential sections show that the base of the zowcia, excepting those in the mar- ginal rows, is bounded by very thin, straight, longitudinal walls, and equally thin transverse partitions. This portion of the zocecium therefore may be described as a parallelogram, with the length and breadth respectively as four is to one. At about the middle of the hight of the primitive cell its sides have spread a little and the ends contracted in a corresponding degree. Just as the posterior half is about to be roofed over two projections from the side walls, at a points a little behind the middle, gradually converge until they meet and thereby cut off and enclose the ellip- tical primitive aperture. In the succeeding stages the principal change is a reduc- tion in the size of the apertures, caused by an internal deposit. These stages are all shown in figs. 6, 7 and.8, but to insure a trustworthy idea of the internal structure of the species, they should be studied in connection with figs. 10 and 11. Compared with associated Bryozoa, the next described F. (2) limitaris only will be found difficult to distinguish. This, however, is due chiefly to the imperfect pre- servation of the surface of most specimens. Good examples of the latter are quickly distinguished by the different character of the longitudinal interspaces, these being occupied by one elongated pit or two smaller ones. The zoarium of E. subrecta is always strictly of the simple type, and never branches except under abnormal conditions. Specimens of this and the following species were catalogued by me in 1886 as Ptilodictya ramosa Ulrich (now Escharopora ramosa).* Comparison with the Kentucky *Pourteenth Ann. Rep. Geol. Nat. Hist. Surv, Minn., p. 102. 172 THE PALEONTOLOGY OF MINNESOTA. (Escharopora,. and Tennessee tpyes of that species was not possible before the following year, when I became satified that the Minnesota specimens were really quite different, though similar in their growth. In EL. ramosa the zocecial apertures are set into regularly hexagonal spaces, and are in no sense to be called “confluent.” Formation and locality.—A pparently restricted to the middle third of the Trenton shales, at Minne- apolis, Minnesota. Fragments of a very similar, perhaps identical, species have been observed in the “ Pierce ” limestone at Murfreesboro, Tennessee. ; Mus. Reg. No. 8208. EscHAROPORA (?) LIMITARIS, 2. Sp. 0” var. PLATE XIII, FIGS. 12 and 13. Under this name I propose to arrange a form that may well be regarded as the beginning of the branching section of the genus Phwnopora, Hall. I would have placed it under that genus but for the fact that I found it impossible to draw a satisfactory line between it and FH. confluens. Ordinarily the branches of the present form are smaller and more evenly convex, their edges less sharp, and with a wider non-poriferous border than in typical FE. confluens; but im other specimens, one in particular, the shape and general aspect of the zoarium is precisely as in the most typical examples of the species. The single constant peculiarity of E. ( 2) limi- taris consists in the development of an elevated rim at the ends of the zocecial apertures, causing them to lose their confluent character, and to assume a definite elliptical shape. At the same time the “channel” has been transformed into an elongated inter-apertural pit. Frequently, instead of the single long pit, the space is divided into two short ones, as in Phenopora wilmingtonensis, and P. incipiens. The usual appearance of the surface may be imagined when I say that it isa intermediate between the appearances represented in fig. 20, plate XII, and fig. 5, plate XIII, on the one side, and figs. 14 and 23, plate XIII, on the other. Fie. 9. Escharopora (?) limitaris ULRIGH. a, small part of tangential section, x50, showing struc- ture immediately beneath the point of bifurcation ; 6. another portion of same where the zoarial margins are parallel. : BRYOZOA. 173 Phawnopora.] As shown in the accompanying cuts, the internal structure brought out in tangential sections is often almost exactly as in Ph. incipiens (plate XIII, fig. 17); other sections, however, in portions at least, show a structure more in accordance with fig. 7, plate XIII. It is evident that FH. (2) limitaris and E. confluens are varieties of one species, but because of their intermediate position between Escharopora and Phenopora, it is scarcely advisable to decide now which of the two names shall take the rank of a species, and which that of a variety. Such decisions should be deferred till we are better acquainted with the developmental history of fossil Bryozoa. Formation and locality —Not uncommon in the lowest third of the Trenton shales, at Minneapolis, Minnesota. Also in the middle third of the shales at the same locality, but less common and of more robust growth. A single specimen was observed among a lot of Bryozoa marking the lower shales, collected by Messrs. Schuchert and Scofield, near Preston, Minnesota. Mus. Reg. No. 5930. Genus PHASNOPORA, Hall. Phenopora, HAL, 1852, Pal. N. Y., vol. ii, p. 46; Utricu, 1882, Jour. Cin. Soc. Nat. Hist., vol. v. p. 152, and 1890, Geol. Sur. L1., vol. viii, p. 392; FOERSTE, 1887, Bull. Sci. Lab. Denison University, vol. ii, p. 157. Zoaria bifoliate, simple or branching, the base pointed and articulating into a small basal expansion, the same as in Ptilodictya and E’scharopora. Zocecial arrange- ment regular, in longitudinal, diagonally intersecting and transverse rows, with either the longitudinal or the diagonal series predominant. Two mesopores behind each zocecial aperture, one on each side, or one behind the other. Primitive cells elongate, commonly oblique or lozenge-shaped, at other times with the ends rectan- gular, always arranged between straight, longitudinal walls. Monticules, or mere clusters of large cells and mesopores, present when zoaria are wide enough. Type: Phenopora explanata Hall, 1852, Pal. N. Y., vol. ii, p. 46. From the above description it is obvious that the presence of the two mesopores is the only character to be relied upon in distinguishing the genus from Escharopora and Ptilodictya. The genus attains its highest development in the Clinton group, and in most of the species from that horizon the primitive cell has a peculiar oblique shape that is not seen in the Lower Silurian representatives of the genus, nor in any species of Escharopora, but is not uncommon among true Upper Silurian Ptilodictya. As might be expected, it is among the unbranched species that the greatest resem- blance to Ptilodictya obtains. Indeed, such species as Ph. ensiformis Hall, and Ph. lonsdalei (Ptilodictya lonsdalet Vine) are in every respect, save in this that they possess the characteristic mesopores, precisely like narrow species of Ptilodictya. In the following classification I have arranged the species in sections the same as under Escharopora. Except in one instance, I have not been able to obtain 174 THE PALEONTOLOGY OF MINNESOTA. {Phznopora. specimens of the European species, described mainly as Ptilodictya, that I suspect to belong to this genus. Under the circumstances it would not be safe to include them. Section a, zoaria simple, without monuticules. Phcenopora ensiformis Hall, Clinton group, New York, Canada, Ohio and Indiana. P. lonsdalei (Ptilodictya lonsdalei Vine), Wenlock shales, England. P. tenuis Hall, Lower Helderberg group, New York. Section b, zoaria simple, with monticules, Phenopora bipunctata (Ptilodictya bipunctata (Van Cleve) Hall,) Clinton group, Ohio. P. constellata Hall, Clinton group, New York and Canada. P. expansa Hall and Whitfield, Clinton group, Ohio. ~ P. punctata (Ptilodictya punctata Nicholson and Hinde), Clinton group, Canada. P. superba (Ptilodictya superba Billings), Anticosti group, Anticosti. P. wilmingtonensis Ulrich, Cincinnati group, Illinois. Section c. zoaria branching. Pheenopora excellens (Ptilodictya excellens Billings), Anticosti group, Anticosti. P. explanata Hall, Clinton group, New York and Canada. P. fimbriata (Ptilodictya fimbriata James), Clinton group, Ohio. P. incipiens Ulrich, Trenton group, Canada and Vermont. P. lindstreemi Ulrich, Upper Silurian, Gotland. P. magna (Stictopora magna Hall and Whitfield), Clinton group, Ohio. P. multifida (Stictopora multifida (Van Cleve) Hall), Clinton group, Ohio. Though fully convinced that some of these species are synonymous, it seemed best to retain all names until an opportunity offers to treat the genus in a mono- graphical way. PHANOPORA INCIPIENS 1. Sp. PLATE XIII, FIGS. 14-17. Zoarium small, dividing dichotomously at rather long intervals ; basal extremity long, slender, subcylindrical, with fewer and more elongate zocecial apertures than above the first bifurcation. Branches 1.5 to 2.0 mm. wide, compressed, rigid, edges sharp, parallel, with moderately developed striato-punctate, non-poriferous border. Zocecia in from twelve to fifteen alternating ranges, very regularly arranged in long- itudinal, diagonally intersecting and transverse rows, with respectively eleven in 5 mm., ten in 2.5 mm., and fiveinl] mm. Zocecial apertures of equal size, elliptical, enclosed in a minutely papillose rim or peristome, the latter slightly depressed at the ends, and generally in contact with each other at four points, so that with a side- light the apertures may appear as arranged between alternately converging and diverging raised lines. End interspaces elongate, depressed, commonly occupied by two mesopores, in other cases by three, and rarely, except in the marginal rows, by four or more now in double rows; always disposed in a longitudinal manner. Non-pouiferous border occupied by two or more rows of mesopores. BRYOZOA. 175 Phxnopora.] This form is easily distinguished from all the branching Clinton group species of the genus by the longitudinal arrangement of the mesopores. It is, however, especially in its internal structure, very similar to, and perhaps a descendant of, Escharopora (?) limitaris. Still, its branches are narrower and more rigid, and there is not that difference in the size of the central and marginal rows of zocecia that pertains to that Minnesota species. Formation and locality—Trenton limestone, Montreal, Canada, and Chimney Point, Vermont. Recently a fragment apparently identical with the eastern types of the species was collected at St. Paul, Minnesota, by the author, in the Galena shales, Collectors, Mr. T. C. Curry and Prof. Henry M. Seely. PHANOPORA .WILMINGTONENSIS n. Sp. PLATE XIII, FIGS. 22-26. Zoarium a simple lanceolate frond, straight or slightly curved, tapering to a point below, 40 to 100 mm. or more in length, 6 to 24 mm. wide, and 1.0 to 2.5 mm. thick at the center; edges acute, non-poriferous margin inconspicuous, surfaces gently convex, sometimes a little flattened on each side of the center, exhibiting, according to the width of the frond, from one to ten rows of low monticules. The latter occur at intervals of 2 or 3 mm., are usually arranged in rather irregular longitudinal and diagonal rows, and occupied by greater or smaller aggregations of mesopores and zoccia, the latter of slightly larger size than the average. Zoccial apertures subcircular or ovate, arranged in regular diagonally intersecting and transverse rows ; often, especially in the lower half of the zoarium, with the enclosing rim depressed at the ends, in which case they appear to be longitudinally confluent. Longitudinal interspaces depressed, generally with two small mesopores, one just in front of, the other immediately behind each aperture. Toward the center of the monticules the number of the mesopores in each interspace is gradually increased to four or more. Measuring lengthwise, about twelve apertures in a direct line 5 mm. long, and twenty-three or twenty-four of the transverse rows in the same distance ; diagonally, twenty, and transversely twenty-three or twenty-four in 5 mm. In tangential sections the base of the primitive cells is greatly elongate and bounded by subparallel sides and slightly oblique end walls. Very soon after, the anterior two-thirds is swollen and a curved hemiseptum thrown out from one side, which continues till it joins the opposite wall, thus enclosing the primitive aperture. Preceding this the walls are very thin, but now they add to their thickness by internal deposit. At the same time the aperture assumes a more rounded shape, the walls approach laterally so that each cell is, normally, in contact with six of its neighbors. Between these points there is a triangular open space or mesopore. 176 THE PALEONTOLOGY OF MINNESOTA. [Arthropora. The walls consist, first, of the original, transversely lined (? minutely perforated) investment, and, second, of an inner laminated deposit (see fig. 25). This structure prevails in all the typical genera of the Ptilodictyonide, but, unfortunately is rarely preserved. Every important feature noticed in vertical sections is represented in fig. 26. When plate XIII was lithographed the specimen thereon illustrated was the only one then available. When, several months later, the remainder of my collections from Wilmington, Illinois, was unpacked, I was fortunate enough to find seven more examples, three of them with the pointed basal extremity. The presence of mesopores distinguishes this species from Lower Silurian Escharopora, like E. maculata Ulrich, while their longitudinal arrangement serves to separate it from the unbranched Upper Silurian species of Phenopora. Formation and loculity.—Upper beds of the Hudson River group, at Wilmington, Illinois. Genus ARTHROPORA, Ulrich. Ptilodictya and Stictopora ( part.), of several authors. Arthropora, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 152; S. A. MILLER, 1889, North Amer. Geol. and Pal., p. 293; Unricn, 1890, Geol. Sury. Ill., vol. viii, p. 393. Zoaria bushy, spreading in a plane, composed of numerous, essentially equal segments; joints simple, bifurcating, or with several short lateral branchlets, the extremities solid and rounded for articulation with succeeding segments. Zocecial apertures elliptical, surrounded by a delicate peristome. Interspaces with one or more thread-like ridges, variously disposed, sometimes short and vermicular, at other times forming continuous longitudinal wavy lines, or ranged in a concentric manner about the apertures. Peristomes and ridges each with a row of minute papille. Interior with the primitive cell elongate, narrow, one or both hemisepta, and lined with minute dots (? median tubuli) between the zocecia in the peripheral region. Mesial lamine zigzag in transverse sections, without “median tubuli.” Type: Arthropora shafferi. (Stictopora shafferi Meek). Range, from base of Trenton formation to top of Hudson River group. This genus is closely related to Graptodictya, the only difference being that in the species of that genus the zoarium is continuous above the basal articulation, while in Arthropora it is divided into subequal joints. In certain of the internal characters, (e.g. the rows of interstitial dots) we are reminded of the Rhinidictyonide, but the general agreement with the Ptilodictyonide, especially in the absence of minute tubuli between the mesial lamin, precludes all likelihood of near relation- ship with Rhinidictya. BRYOZOA. 177 Arthropora.] The three species next following and A. shafferi (Meek) are the only species so far published of which we know positively that they belong to Arthropora. There are, however, at least three other distinguishable forms in the Cincinnati group of Ohio, Indiana and Kentucky, each marking a particular horizon in the group. Most of the species are abundant, but it is exceedingly rare to find any number of the ség- ments still joined together, or lying in their original order. ARTHROPORA SIMPLEX Ulrich. PLATE XIV, FIGS. 12-21. Arthropora simplex ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 65. Zoarium jointed, rarely found except as isolated segments. Normally developed, the segments are narrow, more or less compressed, unbranched, straight stems, rounded and solid at each end, with sharp edges and striated non-poriferous border ; 12 to 19 mm. long (average length about 18 mm.), 1.0 to 1.8 mm. wide, and always less than 1.0 mm. in thickness. The basal or primary segment is irregularly branched, and occasionally some of the succeeding segments are divided, but such divisions are evidently abnormal. A single specimen preserves several joints in their natural position, From this it appears that, as a rule, the upper extremity of each segment articulated with two succeeding segments. Basal segments thickest, sometimes nearly cylindrical, their superficial characters obscured, the peristomes and interstitial ridges thickened and the zocecial apertures reduced in size through age. In the younger segments, and most specimens are to be so classed, the characters are as follows: zoccia very regularly arranged in transverse and diagonally intersecting series, with five in 1 mm. transversely, and eleven or twelve in 3 mm. diagonally ; twenty-four to twenty-six of the transverse rows in 5 mm. longitudinally. Zocecial apertures elliptical, surrounded by a very thin, granose peristome. The latter is easily overlooked, strongly depressed at the sides, but elevated and prolonged at each end, in most cases not far enough to con- nect succeeding apertures ; separating the longitudinal rows an elevated, thin, papil- lose, wavy ridge. In passing around the zocwcial apertures these ridges alternately diverge and converge, two coming close together, often even uniting, in the spaces between the sides of the apertures. In many segments only the raised ends of the inner depressed ring of papillee are distinguishable. In these cases the longitudinal ridges combine in front and behind the apertures so as to produce an appearance similar to fig. 22, plate XIV. =! 178 THE PALEONTOLOGY OF MINNESOTA. {Anthropora. In figures 21 a, b, c, | have endeavored to show all the characters of the zocecia that are to be brought out in tangential sections. The right sides of a and 6 repre- sent the structure just beneath the surface, while the left sides show it at a deeper level in the section. In 21 ¢ only the primitive or prostrate portion of the zocecia is shown. The unbranched character of the segments of this species, as well as their greater length, will distinguish them at once from all other species of the genus. Formation and locality—Very abundant in the lower and middle thirds of the Trenton shales, at Minneapolis, St. Paul, Fountain and other localities in Minnesota; Decorah, Iowa. Mus. Reg. Nos. 5933, 8075. ANTHROPORA BIFURCATA 2. Sp. PLATE XIV, FIGS. 22-25. ~ Segments small, thin, with sharp edges and rather wide non-poriferous border, the lower ones bifurcating, usually only once; so far as observed not over 8 mm. long, and from 1.2 to 1.8 mm. wide; the upper joints shorter, their length occa- sionally less than 5 mm., bifurcating, or with a single lobe-like projection on one or both sides. Young segments with comparatively large, ovate zoccial apertures, not very regularly arranged in longitudinal and diagonally intersecting series, with about nine in 3 mm. lengthwise, and five in 1 mm. diagonally. Apertures enclosed in distinct granulose rims, connecting longitudinally. Interspaces depressed, some- times with a few indistinct strie. With age the zocecial apertures become more circular and smaller, and the peristomes and connecting ridges thicker. This species is related to A. shafferi (Meek) but differs in having only one ridge or line in the interspaces, instead of from one to four. A. simplex has longer and unbranched segments, while A. veversa has a peculiar horseshoe-shaped ridge about its zocecial apertures. Formation and locality.—Detached segments rather common in the Galena shales and in the upper third of the Trenton shales at St. Paul, and Cannon Falls, Minnesota. A closely allied species, perhaps it is identical, in the Trenton limestone of Kentucky, Tennessee, and Canada. Mus. Rey. No. 8108. ARTHROPORA REVERSA 1. Sp. PLATE XIV, FIG. 26. Of this species I have seen only two segments, but their superficial aspect is so distinctive that I do not hesitate in proposing a new name for them. One of these is 8 mm. long, and divides dichotomously about midway the length. ‘The two forks are of the same strength as the lower half, averaging 1.2 mm. wide, the three extremities abrupt and tipped for articulation with the preceding and succeeding BRYOZOA. , 179 Stictoporella.] segments. The other, apparently the basal or primary segment, is pointed below trifurcately divided 4mm. above the lower extremity, with the three branches of equal strength and the central one again divided, this time merely bifurcating, at its upper end; total length 8 mm., width about 10mm. The zoarial growth and general aspect of the segments seems therefore to be precisely as in A. bifurcata. Zocecial apertures small, subeircular, separated from each other by spaces fully equalling their diameter ; arranged in rather irregular, more or less oblique trans- verse series, about six in 1 mm., and in six to eight, more regular, longitudinal rows, with twelve to fourteen in 3mm. Immediate border of apertures formed by a ring of very minute granules. This ring is depressed except at the lower end, so that it is not likely to be seen save under the most favorable circumstances. The lower end is commonly prolonged into one or two short rows of granules, perhaps extend- ing completely across the end interspaces. The most striking peculiarity of the species is a horseshoe-shaped ridge, open below, which, in the usual state of preser- vation, appears to enclose the sides and upper end of each zocecial aperture. This ridge is papillose, thick, and strongly elevated in the middle (in front of each aper- ture) gradually tapering to the ends. The strong elevation in front of the apertures, causing them to appear as oblique and turned backward, suggested the name rever'sa. The ends of the horseshoe ridge may be free, (see fig. 26) or they may unite with the sides of the one next beneath. Non-poriferous border rather wide, with distinct, oblique rows of papillix. Formation and locality.—Upper third of the Trenton shales, at St. Paul, Minnesota. Recent collec- tions made at this locality from this horizon and the overlying Galena shales afford a considerable number ot detached segments agreeing in all essential features with the described types of the species. Mus. Reg. No. 8109. Genus STICTOPORELLA, Ulrich. Stictoporella, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, pp. 152 and 169; and 1890, Geol Sury. IlJ., vol. viii, p. 394; Vine, 1884, Fourth Rep. Brit. Assoc. on Foss. Poly., p. 44; Mricuer, 1889, North Amer. Geol. and Pal., p. 328. Zoaria bifoliate, growing from a broad basal expansion into narrow, parallel margined, branching stipes, simple leaf-like fronds, or cribrose expansions. Zocecia with the primitive portion tubular, unusually long, generally without hemisepta, the inferior one only occasionally present. Apertures elliptical, placed at the bottom of a sloping area, the latter usually polygonal. More or less numerous, thick-walled, untabulated mesopores occur between the zocecial apertures and line the zoarial margins. Maculz, composed of clustered mesopores, and sometimes of zocecial aper- tures of larger size than the average, commonly scattered over the surface of the frondescent species. 180 THE PALEONTOLOGY OF MINNESOTA. [Stictoporella. Tangential sections of favorably preserved specimens show that both the zocecia ~ and mesopores are separated from each other by a sharply defined line of minute pore-like dots. True median tubuli and diaphragms wanting. Type: S. interstincta Ulrich. Range, Lower Trenton to Chester. For remarks on the relations and systematic position of this genus see ante p. 162. The range of zoarial diversity allowed in this genus is unusually comprehensive. Perhaps it is too much so, and that the cribrose species ought to be distinguished generically. Most certainly they look very different from the others and are, I grant, as much entitled to generic separation as Clathropora, Hall, Cosciniwm, Keyserling, and other genera that might be mentioned, all differing from related genera chiefly or solely in the cribrose character of the zoaria. Though inclined to favor a sepa- ration, I have decided to leave them with Stictoporella for the present. CLASSIFICATION OF AMERICAN SPECIES. Section a: zoarium branching. Stictoporella interstincta Ulrich, Utica horizon, Cincinnati group, Kentucky. S. angularis Ulrich, base of Trenton shales, Minnesota. S. angularis var. intermedia Ulrich, base of Trenton shales, Minnesota. S. dumosa Ulrich, Trenton shales, Minnesota. S. rigida Ulrich, Trenton shales, Minnesota. Section 6: zoarium wide, leaf-like, with macule. Stictoporella frondifera Ulrich, base of Trenton shales, Minnesota. S. ? basalis Ulrich, Keokuk group, Illinois, Iowa. S. ? undulata Ulrich, Chester group, Kentucky, Ilinois. Section c: zoarium cribrose. Stictoporella cribrosa Ulrich, middle Trenton shales, Minnesota. ?Clathropora flabellata Hall, Trenton, Wisconsin. Stictoporella proavia (Coscinium proavium Billings, ? Hichwald), Trenton, Canada. S. n. sp.(with smaller meshes than in the others), ‘‘ Pierce” limestone, Tennessee. STICTOPORELLA RIGIDA Ulyich. PLATE XI, FIGS. 20 and 21. Sticloporella rgida ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 188. Original description: “ Zoarium a narrow branching, bifoliar stipe. Branches flattened, 1.0 mm. or a litle more wide, with straight parallel and sharp margins, acutely elliptical in cross-section. Zocecia in seven to nine or ten rows on each face, their apertures arranged in very regular longitudinal and diagonally intersecting series, with sixteen or seventeen in 5 mm. lengthwise and four in 1 mm. obliquely. Apertures elliptical, 0.2 mm. long, half that wide, impressed, the sloping area narrow for this genus, and appearing sometimes a little oblique because of a slight elevation of the posterior border; those in the marginal rows are directed slightly outward. BRYOZOA. 181 Stictoporella.] Between the ends of succeeding zocecial apertures one or two small mesopores. There is usually a row of these small pores along the border of the branches. Inter- spaces narrowly rounded or ridge-shaped, comparatively thin.” This neat species is near S. interstincta from the Utica horizon of the Hudson River group, but has somewhat narrower branches, fewer mesopores, and much thin- ner walls. In S. angularis the walls are much thicker, branches wider, sloping areas about the zocecial apertures polygonal, and the mesopores less numerous and irregu- larly distributed. S. dumosa has wider and oftener divided branches. Formation and locality.—Rare in the lower part of the upper third of the Trenton shales, at St. Paul, Cannon Falls, and near Fountain, Minnesota. STICTOPORELLA DUMOSA 7. Sp. (Not figured.) Zoarium forming bushy masses, as much as 100 mm. in diameter and 50 mm. high, consisting of very irregularly divided, free or coalescing, small branches, 1.5 to 2.0 mm. in width, and usually less than 0.5 mm. in thickness. Zocecial apertures subcircular or elliptical, set into rather wide sloping areas of polygonal or rounded outline, the shape depending upon the number of mesopores present. Arrangement rather irregular; occasionally longitudinal rows, with the mesopores between the ends of the zocecial apertures, prevail, in which case the surface appearance is much the same asin S. rigida. More commonly, however, a diagonal arrangement predom- inates, with the mesopores distributed more at random. In these, especially when the mesopores happen to be fewer than usual, the general appearance is much more like that of S. angularis. Where the arrangement is the most regular there are ten or eleven zocecial apertures in 8 mm. diagonally, and about eight in the same space longitudinally. Apertures often closed by a slightly convex plate, in which a minute subcentral perforation may be detected. Walls ridge-shaped, generally wider than the diameter of the zocecial apertures. Mesopores varying in number; sometimes a fragment will show about one only to each zocecium, while others may have them three or four times as numerous. Edges sharp, generally exhibiting two or three rows of mesopores. Internal structure, especially in transverse and vertical sections, very similar to that of S. cribrosa. In tangential sections the mesopores are not as distinct, and the divisional line between the zocecia less sharply defined, than in similar sections of that species. Asa rule, I do not favor descriptions of species without illustrations, but in this ~ ease the form is so easily recognized that the omission may be pardoned. Com- pared with S. angularis it is distinguished by its more irregular and stronger growth, 182 THE PALEONTOLOGY OF MINNESOTA. [Stictoporella. and more abundant mesopores. The occasional inosculation of the branches points to a relationship with S. cribrosa, and this is further evidenced by the agreement in their internal structure. The position of the species is probably intermediate between S. angularis and S. eribrosa. Formation and locality—Upper third of the Trenton shales at St. Paul, Minnesota. Mus. Reg. No. 8110. STICTOPORELLA ANGULARIS Ulrich. PLATE XI, FIGS. 1-3, 6, and 8-11. Stictoporella angularis ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 71. Zoarium branching dichotomously at intervals varying from 4 to 10 mm.; branches more or less compressed, 1.5 to 3.0 mm. wide, 0.7 to 2.0 mm. thick, with sharp or nar- rowly rounded, subparallel edges. Zocecial apertures small, subcircular, set into wide sloping polygonal areas, with the subrhomboidal and hexagonal shapes commonest. Walls ridge-shaped, angular in the middle, their thickness usually greater than the diameter of the apertures. Zocecial apertures arranged in moderately regular curved diagonally intersecting series, nine in 2.6 mm. When longitudinal rows are to be made out (as in upper part of fig. 6) six are to be counted in the same space lengthwise. Mesopores comparatively few, small, sometimes appearing to be absent entirely on parts of the central three-fifths of the surface, while for some distance above or beneath such a spot they may occur regularly one to each zocecium. Near the margins, however, some are always present, with one and occasonally two rows bordering the edges. In tangential sections, showing the structure in the peripheral part of the zoa- rium, the zocecial cavity is ovate, in old examples sometimes nearly closed by inter- nal deposits of sclerenchyma, the interspaces always thick enough to separate the cells by a distance greater than their diameter. Boundary line between the zoccia and mesopores sharply defined, consisting of a crowded row of very minute, pore-like dots. These, however, are not recognizable except in the most favorably preserved specimens. Mesopores few, here completely filled with laminated sclerenchyma. In vertical sections the thin-walled prostrate part of the zocecial tube is long, but, as is usual in this genus, this portion of the section appears irregular. Hemi- septa absent. In turning to the surface the tube bends abruptly, and at once the walls become very thick and marked with j-shaped lines representing the sloping areas about the apertures at previous stages of growth. The angularity of the zocecia, together with the unusual paucity of the meso- pores, distinguishes this species from S. interstincta, S. rigida, S. dumosa and S. cribrosa, BRYOZOA. 183 Stictoporella.] The broad, maculose zoaria of S. frondifera are not likely to be confounded, although the two species are undoubtedly closely related. The following variety is good evi- dence of that. Formation and locality—Not uncommon in the lower third of the Trenton shales, at Minneapols, St. Paul, and several localities in Goodhue and Filmore counties, Minnesota. Mus. Reg. Nos. 5943. 7617. STICTOPORELLA ANGULARIS, Var. INTERMEDIA 2. Vr. PLATE XI, FIGS. 4, 5 and 7. This name is proposed provisionally for a form that is common at several locali- ties in Filmore county, but rare in the more northern exposures of the same beds. It differs from typical S. angularis, with which it is often associated, in forming wide, irregular branches, the growth and size being in many instances precisely as in the branching form of S. frondifera. At intervals the surface presents clusters of zocecia with thinner walls and larger apertures than usual. The mesopores are very few, in most cases restricted to the center of the clusters mentioned. Here they may form aggregations, but these are never, as far as observed, so extensive as in S. frondtfera One or two rows of them are also commonly present at the rounded margins of the branches. In having very few mesopores the variety agrees with S. angularis, while in its wide branches and general aspect it is like S. frondifera. The name intermedia alludes to its position between those species. Formation and locality.—Rare near the base of the Trenton shales, at Minneapolis, but common in the same beds near Fountain, Lanesboro and Preston, all localities in Minnesota; also at Decorah, Lowa Mus. Reg. Nos. 7597, 7599, 7984. STICTOPORELLA FRONDIFERA Ulrich. PLATE XI, FIGS. 12-19. Stictoporella frondifera ULRICH, {ss6. Fourteenth Ann. Rept. Geol. Nat. Hist. Surv. Minn., p. 72. Zoarium consisting of broad, irregularly branching, flabellate or undulate expan- sions, | or 2 mm. in thickness, the whole attaining a hight of from 50 to 100 mm. Edges rounded, with small pits (mesopores) in two or more rows. Surface with con- spicuous macule consisting of greater or lesser aggregations of mesopores, sometimes a hundred and more, generally about fifty or less. These macule are from 3 to 5 mm. apart, sometimes arranged in rows, but oftener their distribution is decidedly irregular. Between them the surface is occupied by the rounded zocecial apertures and meso- pores, the latter small and unequally distributed, varying in number from one, two, or even three to each of the former, Walls ridge-shaped, thick, usually nearly 184 THE PALEONTOLOGY OF MINNESOTA. [Stictoporella. equalling the diameter of the zocecial apertures. Arrangement variable, rather irregular, generally in diagonally intersecting series, with from fifteen to eighteen, but averaging sixteen in 5 mm, Internal structure, as shown in thin sections, very similar to that of S. angularis, the only differences noticed resulting from the much greater development. of mesopores. The much greater abundance of mesopores distinguishes this species from S. angularis, var. intermedia, while the frondescent habit of its zoarium separates it from all the other Lower Silurian species of the genus. Associated in the same strata are Pachydictya foliata and Phyllodictya frondosa ?, two bifoliate species likewise characterized by foliaceous zoaria. In other respects, however, they differ so obvi- ously from S. frondifera, that detailed comparisons are rendered unnecessary. Formation and locality.—Rather abundant in the lower beds of the Trenton shales, at Minneapolis, St. Paul, Preston, near Fountain, and other localities in the state where this horizon is exposed. Mus. Reg. Nos. 5945, 5947, 7650. STICTOPORELLA ORIBROSA Ulrich, PLATE X, FIGS. 21-25; PLATE XI, FIGS. 22 and 23. Stictoporella? cribrosa ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Sur. Minn., p. 69. Zoarium growing from a small expanded basal attachment into thin erect fronds, perhaps 50 mm. in diameter, composed of branches that inosculate at short intervals till there is produced a broad expansion perforated at more or less regular intervals by circular or elliptical fenestrules. Both sides of frond celluliferous, consisting of two equal layers of cells grown together back to back in the manner usual with bifoliate Bryozoa. Fenestrules elliptical, sometimes circular, varying greatly, the average size about 1.38 mm. by 1.8 mm., or less than the width of the branches ; but the same frond may show extremes like 1 mm. and less, and 3.5 mm. Their arrangement is therefore more or less irregular, and taking other cribrose species of the genus into consideration, this irregularity in the size and distribution of the fenestrules is to be considered as a characteristic of the present species. Width of branches generally 2.0 mm. or 2.5mm. but varying between the extremes of 1.5 mm. and 3.1 mm. Zowcial apertures small, subcircular or elliptical, the average size about 0.1 mm. by 0.12 mm., set into sharply defined, polygonal or rounded, sloping areas, about nine in 2.5mm. Mesopores small, numerous, often completely isolating the zocecia. Generally, however, the latter are in contact with each other at limited points. Around the fenestrules there is a band, 0.5 mm. or less wide, occupied solely by mesopores. As in other species of the genus the BRYOZOA. 185 Arth rostyllida. | zocecial apertures are often closed by a convex plate, with or without a minute subcentral perforation. Tangential sections show that the polygonal boundary of the zocecia is marked by a dark line, which under favorable preservation will probably consist of a row of exceedingly minute pore-like dots. Visceral cavity ovate or subcircular, generally of less width than the walls. Mesopores numerous, of irregular shape and unequal dimensions, often completely filled, or only preserving a very small central cavity. Vertical sections show that the divisional lamin are somewhat flexuous, the tubes at first thin-walled and prostrate, overlapping each other for some distance, that they subsequently bend abruptly outward, and that their walls at the same time are much thickened and marked with oblique lines parallel with the form of the apertures. The mesopores appear as narrow open spaces when not entirely filled by the secondary deposit of sclerenchyma. Diaphragms and hemisepta wanting. af The Canadian Trenton limestone species identified by Billings with Eichwald’s Coscinum proavium, is closely related to S. cribrosa, but differs in having narrower branches, subequal and more regularly disposed fenestrules, and less numerous mesopores. Another cribrose species, but in every respect smaller than these, occurs in the “ Pierce” limestones at Murfreesboro, Tennessee. Still another Lower Silurian bryozoan with inosculating branches has been described by Hall from the Trenton rocks of northern Wisconsin.* He named it Clathropora flabellata, but both the description and figures are entirely inadequate for anything like satisfactory identification. It may belong to Clathopora, but Stictoporella is more likely to be right. Then again it is not impossible.that it is a Coscinella or even a Coscinum, since in all of these paleozoic genera the zoarium is cribrose. Compared with the characters shown in Hall’s figures, it is evident that he had before him a more robust species, with branches and fenestrules much larger than in S. cribrosa. Formation and locality.—A bundant in the middle third of the Trenton shales at Minneapolis and St. Paul, Minnesota. The species seems to be restricted to this horizon. Family ARTHROSTYLLIDA, Ulrich. This interesting family of small Bryozoa is strongly represented in the Lower Silurian rocks of Minnesota. On account of the minute proportions of most of them their dismembered zoaria are generally to be found only by searching the surface of the slabs of fossiliferous limestone that occur so abundantly in certain parts of the Trenton shales. These are often full of the separated joints. The most satisfactory *Foster and Whitney’s Report, vol. 2, p. 207, 1851. 186 THE PALEONTOLOGY OF MINNESOTA. (Arthrostyllide. specimens, however, are those which are obtained by picking over the residue of washings of the shales themselves. These are better, not only because they can be studied from all sides, but because their preservation is, in most cases, more favorable. Unfortunately, I had neither the time nor the opportunity of making extensive washings of shales in Minnesota, and that method of collecting was employed to only avery limited extent. Here and there a pound or two of unusually rich clay was carried away and washed during leisure moments after my return home. One of these packets proved to cgntain so many interesting things, and withal was so rich in individuals, that it deserves mention. ‘The shale was from the lower part of the Galena shales, which, according to my reckoning, is the exact equivalent of the Trenton limestone of New York. After washing away less than half its bulk nearly two-thirds of the residue consisted of good fossils, of which the larger ones, mainly species of Prasopora, Homotrypa, Callopora, Constellaria, Eridotrypa and some Brachi- opoda, were separated by sifting the finer material away from them. A large pro- portion of this fine material consisted of small fossils, among them five or six species of Ostracoda, (most of them described in this volume as new) and at least eleven species of small Bryozoa. Of the latter eight belong to the family under considera- tion, two of them being species of Arthroclema, three of Helopora, and three of Nematopora. The jointed character, of the zoarium is the most conspicuous and perhaps also the most important feature of the family. It is well shown in all the genera except Nematopora, in which articulation occurs only at the basal extremity, the zoarlum above the base being a dichotomously dividing, continuous stem. In Helopora, Hall, Sceptropora and Arthrostylus, the segments are simple and terminally joined together, and doubtlessly formed bushy zoaria. But in Arthroclema, Billings, the zoarium forms a more or less plumose expansion, divisible into numerous primary, secondary and tertiary segments, those of the first and second order being connected terminally and ranged in straight lines. A deep socket occurs on one or two opposite sides of each of the strong joints of the primary series and a shallow one in most of those of the smaller secondary set, in which respectively the first of the series of the second and third order is inserted. The zocecia are arranged in a radial manner around a central axis and, excepting Arthrostylus in which one side is marked with longitudinal striae only, open on all sides of the subeylindrical segments. In transverse sections the primitive portion of the zocecia is wedge-shaped, but in longitudinal sections they often appear tubular. The length of the tubes depends very largely upon the diameter of the segment, since all of them reach the central axis. It is evident that the obliquity of the tubes also has something to do with their relative lengths. They are, however, not to be con- BRYOZOA. 187 Arthrostylus. ] sidered tubular in the sense attaching to that term when applied to the Cyclostomata. On the contrary they are no more so than are the zovecia of the most typical Rhinidic- tyonide. In tangential sections they are oblong-quadrate or hexagonal in outline. Hemisepta have not been observed, but rows of minute tubuli occur between the walls of adjoining zocecia and sometimes in the longitudinal interspaces in the ves- tibular region. A minute tube is also to be detected running from end to end through the axis of the segments. Respecting the position of the family the jointed character of the zoaria leads us to look for its relationship first with the similarly constructed Cellariide. The latter embraces living forms chiefly, and of many of these I have secured specimens, so that I am now in a position to speak intelligently upon their characters, as com- pared with paleozoic forms. I would be glad to do this here were it not that I would thereby interfere with my plans for a general work on inter-relation of bryozoan types. It will probably be sufficient to say that the two families are distinguishable, and that the relationship between them, if any exists, is almost certainly less inti- mate than that between the Arthrostylidw and Rhinidictyonide. Aside from the wedge-shaped form of the primitive cells in the Arthrostylide, which it is evident resulted necessarily from their radial arrangement about a linear central axis, they are precisely like those of true Rhinidictya. They agree also in possessing median tubuli between the walls of adjoining zocecia. Then again I am convinced that the minute axial tube of the Arthrestylide is functionally identical with the median tubuli between the mesial lamine that are such a characteristic mark of the Rhinidictyonide. The jointed character of the zoarium even, is not unknown in the latter since it pertains to Dicranopora, Ulrich, a genus that in all other respects is precisely like Rhinidictya. Really, I find only one structural differ- ence between the two families, and that is that while the zocecia in the Rhinidicty- onde are arranged so as to form bifoliate zoaria—in other words, are disposed in two equal expansions grown together back to back, they are arranged radially around a central axis, forming subcylindrical zoaria, in the Arthrostylide. Genus ARTHROSTYLUS, Ulrich. Arthronema, ULRICH, 1882. Jour. Cin. Soc. Nat. Hist., vol. v, pp. 157 and 160 (not EscHSCHOLTz, who used the name for a genus of Colpodea). Arthrostylus, ULRICH, 1888. Amer. Geologist, vol. i, p. 230; 1890, Jour. Cin. Soc. Nat. Hist., vol, xii, p. 188; 1890, Ill. Geol. Sur., vol. viii, p. 400. Zoaria bushy, branching dichotomously, the whole consisting of numerous, exceedingly slender, subquadrate, equal segments, joined to each other by terminal articulation, Zocecia arranged in three (perhaps more) rows, usually between 188 THE PALEONTOLOGY OF MINNESOTA. [Arthrostylus. longitudinal ridges; the fourth face, commonly the widest, with longitudinal stricze only. Type: Arthronema tenue Ulrich (Helopora tenuis James), of the Utica horizon of the Cincinnati group. (Jour, Cin. Soe. Nat. Hist., vol. v. p. 160, 1882.) The lower fig. 16 on Plate III, represents a transverse section of this species. It should have been been numbered 16a. Besides the type species only three others are known to have the characters demanded by this genus. ‘Two of these are from the Trenton shales of Minnesota, and are next described. The third species, A. curtus Ulrich, from the Hudson River rocks of Ohio, is still a little doubtful, no further material having been found to throw light upon the rather imperfect originals of the species. ARTHROSTYLUS consuNoTUS Ulrich. PLATE III, FIGS. 13 and 14. Arthrostylus conjunctus ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 189. Original description. “Zoarium jointed ; segments very slender, straight, needle- shaped, 3 or 4 mm. long, quadrangular in cross-section, 0.25 mm. wide, 0.18 mm. thick, with zocecial openings on three sides, the fourth being without them, but marked instead with four parallel longitudinal striz. Zocecial apertures broad-oval, direct, 0.11 mm. long, 0.09 mm. wide, enclosed by a sharply marked peristome. Peristomes of each row of apertures joined together by a thin ridge, having a length about equal to the larger or outer diameter of the peristomes. Hight zocecial apertures in each row in2.5mm, A thin ridge on each side of the range of apertures of the obverse face of the segment separates it from the lateral rows. Apertures usually arranged alternately in the three rows. “This species is closely related to A. tenuis James, sp., but is distinguished by having the non-celliferous side narrower and with fewer striw, causing transverse sections to be more nearly square. The A. obliquus differs in having oblique zocecial apertures.” Formation and locality—Rare near the base of the Trenton shales, near Fountain, Minnesota. In the original description the locality is given, inadvertently, as Minneapolis. ARTHROSTYLUS OBLIQUUS Ulrich. PLATE III, FIGS. 15 and 16. Arthrostylus obliquus ULricu, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 190. Original description: “Zoarium jointed, segments very slender, needle-shaped, straight or slightly curved, about 4 mm long, subquadrangular in cross-section, 0.2 mm wide, 0.15 mm. thick, slightly expanding toward the upper extremity. Zocecia BRYOZOA. 189 Helopora. ] in three rows, occupying as many faces of the segment, the fourth side with three longitudinal striae, and no zocecia. Profile of a segment in an obverse or reverse view, wavy on both sides; in a lateral view only on one side. “Zocecial apertures small, oblique, the posterior margin very prominent, arranged alternately in the three rows, with nine in each, in 2.5mm. A short ridge from the upper depressed edge of each zowcial aperture is flanked on each side by the pro- longed lateral borders of the aperture. No ridge between the lateral and central row of the zocecia. “The oblique zocecial apertures, the prominent lower border and absence of ridges between the rows of apertures, distinguish this species from A, conjunctus and A. tenuis, both of which it resembles in other respects.” Formation and locality.—Trenton shales, Minneapolis, Minnesota ; rare. Genus HELOPORA, Hall. Helopora, HALL, 1852, Pal. N. Y.. vol. ii, p. 44; Brniinas, 1866, (part.) Cata. Sil. Foss. Isl. Antic., p. 836; ULRICH, 1888, The Amer. Geologist, vol. i. No. 4, p. 231, 1890, Jour, Cin. Soc. Nat. Hist., vol. xii, p. 191, and 1890, Geol. Surv. IIl., vol. viii, pp. 401 and 642, Zoaria consisting of numerous, subequal, small, cylindrical segments, articulating terminally, poriferous on all sides. Zocecial tubes somewhat oblique, geniculated or proceeding to the surface in a straight line. Apertures slightly oblique or appearing direct, suboval, arranged in diagonally intersecting series (section a) or between more or less well defined iongitudinal ridges (section 5). In section a the apertures are usually without a peristome, but an acanthopore occurs immediately beneath each. In section b the acanthopores are wanting, but a peristome, generally incomplete and prominently elevated posteriorly, is present. Axial tube very slender. Type: A. fragilis Hall, a common fossil of the Clinton group. As is indicated above, this genus may be divided into two sections. These were noted in my previous work on the genus (loc. cit.) andin one of them I express the opinion that, when these fossils are better understood, these two sections will probably be separated generically. Although the study of the genus, necessitated by the present work, has strengthened this opinion, I am not yet ready to make the separation. Still, I shall go a step farther here and follow the practice adopted in treating many of the preceding genera. As in those cases I believe this non-committal division of the species into sections will suffice until we are in a position to work up the genus monographically. Except in that way it is not only difficult but almost impossible to distinguish nearly related genera in a fully satisfactory manner. 190 THE PALEONTOLOGY OF MINNESOTA. (Helopora. Section a embraces the species which agree nearest with the type of the genus, and all of them, as far as known, belong to Upper Silurian rocks (including the Anticosti group). They are distinguished from the species of section } (1) by the presence of acanthopores, one of which is commonly situated in each end space ; (2) the absence of longitudinal ridges and inter-apertural striz ; (3) the predominance of the diagonal arrangement of the zocecial apertures; (4) the absence of a peristome, the interspaces being highest midway below the zocecial apertures and sloping into them, and (5) the lesser separation of the zocecial apertures longitudinally. Under section a I would place H. fragilis Hall, from the Clinton of New York, Canada, and probably Ohio; H. bellula, H. armata, and H. nodosa, three species described by Billings from the Anticosti group, and H. lindstremi Ulrich, from the Upper Silurian of the island of Gotland. Section 6 differs from the typical section {1) by the absence of acanthopores; (2) the presence of straight or wavy ridges and minor striations of the surface; (3) the predominance of the longitudinal and transverse arrangement of the zocecial aper- tures; (4) the prominence of the zocecial apertures, especially at the inferior side, and (5) in the more ornamental appearance of the segments resulting from the pecu- hiarities noted. Helopora spiniformis, originally described by me as Arthroclema spiniforme (Jour. Cin: Soc. Nat. Hist., vol v, p. 161, 1882), may well be accepted as the type of this section. This species is fairly abundant on slabs of “Glade” limestones, at Lebanon, LaVergne, and other localities in Tennessee. ‘Figs. 4, 5 and 6, on plate ILI, intro- duced chiefly for comparison with H. divaricata, illustrate its principal characters. Segments of apparently the same species were collected also in the lower limestones at Dixon, Illinois. All the other known Lower Silurian species referred to the genus must be arranged in section b. These are H. quadrata, n. sp., H. mucronata Ulrich, and H. (?) sp. undet., from the Galena shales of Minnesota, the last two with rather striking resemblances to certain Cylostomata; H. harrisi James, HH. elegans, n. sp., and HH. imbricata Ulrich, from the upper beds of the Cincinnati group of Ohio and Illinois; and H. alternata Ulrich, from the Trenton shales of Minnesota. The last represents a peculiar type of the section that is again met with, but less strongly expressed in the new species H. elegans. As is to be expected, it is in section that’ Helopora most nearly approaches the other genera of the family. The species of section a represent a further differenti- ation of the type. Comparing the former with Here and there a young zoccium is met with, but true mesopores and acanthopores as well, are unquestionably wanting. In vertical sec- tions the walls form nearly straight lines (merely curving to adapt themselves to the growth of the zoarium) being entirely without the crenulations so characteristic of the typical species of the genus. Diaphragms also seem to be wanting, and most of the tubes of specimens from shaly strata are in great part filled with the matrix. At first I believed this species must be the same as the M. rectimuralis Ulrich, the types of which were collected from nearly equivalent beds in southern Illinois. The absence of diaphragms was explained by the supposition that they had been -20 306 THE PALEONTOLOGY OF MINNESOTA. {Monotrypa nodosa. destroyed during the process of fossilization. But the study of new material, and other sets of thin sections shows that this explanation is inadequate, since, while the diaphragms are always absent in this form they are present in all associated Bryozoa; and it stands to reason that the conditions under which the two sets of specimens were preserved must necessarily have been identical. I am obliged there- fore to consider their absence in the Monotrypa as normal, and to give these peculiar Minnesota specimens a new name. M. intabulata agrees with M. rectimuralis* not only in the external appearance of the zoarium but in having straight walls and minute triangular open spaces at the angles of junction as well. As differences we have diaphragms two to four times their diameter apart, and rather conspicuous clusters of large cells in the latter and none in the former. Among associated forms only Monticulipora grandis and Bythotrypa laxata have a similar growth, the species of Prasopora and Mesotrypa torming discoidal zoaria. Both of these species however are too widely different structurally from Monotrypa to be confounded. Formation and locality.x—Not uncommon in the upper part of the Galena shales (Fusispira beds) at several localities in Goodhue and Fillmore counties, Minnesota. Mus. Reg. No. 8379. MoNOTRYPA NODOSA, 2. Sp. (Not Figured.) Monticulipora (?) ortoni WHITFIELD, 1882. Geol. Wis., vol. iv, p. 251. (Not Cheetetes ortoni NICHOL- son, 1875. Pal. Ohio, vol. ii, p. 211.) Zoarium commonly beginning its growth upon shells over and beyond which it spreads till it forms large discoidal or hemispheric masses, often over 5 or 6 cm. in diameter. Sometimes the masses are shapeless, but as a rule the base is concave, and, where it projects beyond the covered shell, clothed with a wrinkled epitheca. Upper surface with more or less prominent subconical moénticules, averaging about 3.4mm. from summit to summit. Zocecia with thin walls, polygonal and rather regularly arranged apertures, nine or ten in 3 mm.; apertures occupying the mon- ticules but little if at all larger than those in the intermediate spaces. Summits of monticules occasionally appearing solid. Not a trace of either mesopores or acan- thopores has been observed. Internal characters unknown, none of the specimens seen being fit for sectioning. *In the original description of the species I included, erroneously, a hemispheric or lenticular, tuberculated form that is _ very common in the Hudson river rocks at Savannah, Illinois, and Delafield and Iron Ridge, Wisconsin. As it may justly be expected to occur in the southern part of Minnesota, the next brief description of its known characters may be of advantage to students of the paleontology of the State. BRYOZOA. 307 Monotrypa (? Chetetes) cumulata.] In the absence of any knowledge of the interior the generic position of the species is necessarily a little doubtful. In a general way, M. nodosa resembles Leptrotypa filiosa d’Orb. sp., of a lower horizon in the Hudson river rocks, very closely, and the principal difference that can now be pointed out is in the size of the zocecia, that species having eleven or twelve apertures where the present form has nine or ten. But Atactoporella ortoni Nich. sp., to which Whitfield referred the Wisconsin specimens, is a delicate parasitic form totally distinct. Formation and localityx—Common in the upper beds of the Hudson river group at Iron Ridge and Delafield, Wisconsin, and Savannah, Illinois. Mus, Reg. No. 7574. Monorrypa (? CH&TETES) CUMULATA, 2. Sp. PLATE XXVII, FIGS. 26 and 27, Zoarium forming small subglobular or irregular masses, generally consisting distinctly of irregularly superposed layers ; average sizes between 15 and 20 mm. in diameter, anything under or over those extremes being rare; no monticules. Zocecial walls thin; apertures polygonal, of unequal sizes, sometimes forming at long but irregular intervals large clusters in which they are conspicuously larger than elsewhere ; in most cases however the apertures are subequal, with an average of six and one-half or seven in 3 mm. Mesopores and acanthopores wanting. Internal characters: In vertical sections the tubes diverge rapidly and rather irregularly, and their walls present an obscure longitudinal lineation. Diaphragms occur at intervals varying from one to four times their diameter, but their position in neighboring tubes corresponds approximately. In transverse sections the prin- cipal interest attaches to the structure of the walls. In most sections the wall is comparatively thick and seems to be composed of minute columns which, being cut transversely, appear as alternately dark and lighter parts. In this respect the structure of the walls is essentially the same as in true Chetetes, and I would un- hesitatingly have placed the species into that genus had I been able to satisfy myself that the phenomena observed were not-the result of secondary causes. Namely, in some sections the appearance is very different, the wall itself being more sharply defined and thinner than usual (especially where the tubes are filled with matrix instead of calcite) and without the alternating light and dark spots. But where the tubes are filled with calcite the latter for some distance inward from the wall is of a darker color than at the center, and exhibits, strange to say, a spotting not unlike that pertaining to the wall itself in other sections. 308 THE PALEONTOLOGY OF MINNESOTA. [Trematoporide. The external form, though smaller, is much the same as in M. intabulata and other species of the genus, but the zocecia are larger, and none of them have a wall- structure as described above. Formation and locality.—Upper part of the Galena shales (Fusispira beds) at various localities in Goodhue county, Minnesota. Also in the Trenton limestone of Canada. Mus. Reg. Nos. 7629, 7635, 8026. Family TREMATOPORIDA, Ulrich. For remarks on this family see p. 289. Genus TREMATOPORA, Hall. Trematopora, HALL, 1852, Pal. N. Y., vol. ii, p. 149; DyBowsk1, 1877, Die Chetetiden, p. 69; ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 241; 1883, idem.., vol. vi, p. 257; HALL, 1887, Pal. N. Y., vol. vi, p. xiv; ULRICH, 1890, Geol. Surv. Ill., vol. viii, pp. 378, 418. , Not Trematopora, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 153. Zoaria ramose, branches solid, even or montiferous. Zocecia with oval or sub- circular apertures, surrounded by more or less elevated peristome. Interspaces depressed, sometimes exhibiting the closed mouths of the abundant mesopores. Zoccial tubes with thin walls and few diaphragms. Mesopores irregularly angular, generally exhibiting an obscurely beaded appearance in vertical sections, with a diaphragm at the constriction. Acanthopores superficial, of moderate or small size, one or more to each zocecium. Type: T. tuberculosa Hall, Niagara group. The really essential characters of this genus have been most persistently misin- interpreted and overlooked. Even now lam not satisfied that they are fully brought out in the above diagnosis, which is practically the same as the one in volume viii of the Illinois reports. The truth is that more study, especially genealogical, is required before it will be possible to delineate even approximately the limits of the genus. Thus, while almost certain that most of the Lower Silurian species placed here by me (e. g. T. primigenia and T.? nitida) are not really related to 7’. tuberculosa, I find myself unable as yet to justify their placement elesewhere. As stated on a preceding page (289) the type of the genus presents many points of agreement with Batostoma and is probably to be viewed as a later expression of the same type of structure. Not so, however, with 7. ? primigenia and allied species, these being much more like Leioclema, Bythopora and Batostomella, on the one hand, BRYOZOA. 309 Trematopora? primigenia.] and Nicholsonella and Constellaria on the other. And yet, above all, there are pecu- liarities that postpone the determination of the systematic position of the next following species till we can learn something of their ancestors. In the meantime they can remain under Trematopora and their doubtful affinities be indicated by the usual sign. As regards Trematella and Orthopora, two subgeneric names proposed by Hall,* the first is clearly a synonym for Batostomella, Ulrich, the second for Rhombopora, Meek. Both groups are widely different from true Trematopora. TREMATOPORA? PRIMIGENIA Ulrich. PLATE XXI, FIGS. 23-40. Trematopora primigenia ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 97. Zoarium loosely bushy, consisting of small slender ramulets, dividing dichotom- ously at varying intervals; branches cylindrical or compressed, commonly about 2 mm. in diameter, but varying from 1.5 to 4.0 mm., arising in greater or lesser num- bers from a large basal expansion that is thinly spread over some cylindrical body like a crinoid column. Not infrequently the branches inosculate freely. Entire zoaria varying in diameter probably between 20 and 60 mm. Superficial aspect of - zocecia varying with age. In young stages or examples the apertures are more or less oblique, with only the posterior border elevated and the interspaces in a varying degree narrower than the apertures. With age the apertures become somewhat smaller, ovate or subcircular and direct, and the peristome or rim equally elevated all around, while the interspaces were widened till in some examples they are often equal to twice the width of the zocecial orifices. At the same time the interspaces, which as a rule exhibit no sign of the really very numerous mesopores, are roughened, as are also the peristomes, by the development of acanthopores. These vary greatly in size and number. The arrangement of the zocecial apertures is only moderately regular, there being here and there spots in which they are of larger size and more widely separated than usual. An average of twelve or thirteen in 3 mm,, but the number in that distance may vary from eleven to fifteen. Internal characters: In vertical sections the tubes have thin walls, are not entirely vertical, and without diaphragms in the axial region. Near the surface they bend outward rather abruptly when one and sometimes two diaphragms were in most cases thrown across each tube. At the same time an abundant series of mesopores was developed. These are crossed by from two to six diaphragms, the *¥Pal. N. Y., vol. vi, p. xiv, 1887. 310 THE PALEONTOLOGY OF MINNESOTA. (Var. ornata. outer ones of which are much thicker and separated by shorter intervals than the inner pair. This gradual thickening of the diaphragms is more decided in the branches than in the basal expansion, part of a vertical section of which is rep- resented in fig. 40. The walls of the mesopores where two or more occupy an inter- space are strongly zigzag, in some instances appearing not unlike vesicular tissue. In tangential sections the zocecial walls may be thin and occasionally even inflected by the acanthopores (fig. 37), but as a rule they are ring-like, as in figs. 38 and 39, and generally completely separated from each other by a series of unequal and irregu- larly shaped mesopores. The acanthopores are distinct, nearly uniform in size, usually attached to the outer side of the zoccial walls, and number from one to three or four to each zoccium. Var. ornata Ulrich. PLATE XXII, FIGS. 26, 28, 33, 34. Trematopora ornata ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 98. Increased collections have convinced me that this is merely an uncommon variety of T.? primigenia, differing from the typical form of the species, as above described, in having the zocecial apertures a little more elongate and rather more regularly arranged, and in having the peristomes crowned by a crowded row of small papille. Larger spines, as shown in fig. 34, are sometimes present. Var. SPINOSA, ”. var. PLATE XXI, FIGS. 29, 30, 35, 36. Of this form, which, if it proves permanent, should be called a species, I have seen only a few specimens. Though evidently mature they are a trifle smaller than typical 7. ? primigenia, and differ in a number of other minor points from that form. But their principal peculiarity, and the only one that in the present state of our knowedge deserves mention, is the presence of a considerable number of strong spines in the interspaces. A few smaller acanthopores are scattered among the larger ones, but unless searched for they are likely to be overlooked. The large basal expansion, small branches, rounded zocecial apertures and depressed interspaces are features that serve to distinguish this species and varieties at once from all associated ramose Bryozoa. Formation and locality.—The typical form is an abundant fossil in the middle third of the Trenton shales at St. Paul and Minneapolis, while it is not uncommon in the same beds at other localities in the State, notably near Fountain and Preston in Fillmore county. The two varieties are rare and associated with the typical form at St. Paul and vicinity. Mus. Reg. Nos. 6010, 6011, 7654, 7661, BRYOZOA. 311 Constellaria] Genus CONSTELLARIA, Dana. Constellaria, DANA, 1848, Zoophytes, p. 537; NICHOLSON, 1879, Pal. Tab. Corals, p. 292; 1881, Genus . Monticulipora, p. 97; Utricu, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 156; 1883, idem, vol. vi, p. 265; 1890, Geol. Surv. Il1., vol. viii, aad pp. 374, 423; JAMES and JAMES, (part.) 1888, Jour. Cin. Soc. Nat. Hist., vol. xi, p. 29.* Stellipora, DyBowskI, 1877. Die Chetetiden d.Ostb. Silur. form., p. 42. Zoaria subramose or frondescent, growiig erect from a basal expansion which is attached to foreign bodies. Surface with stellate macule, the spaces between the rays more or less elevated and occupied by two or three short rows or clusters of closely approximated zocecial apertures. Zocecia with rather thin walls, small circular apertures enclosed by an elevated rim, equally distributed and partly in contact with each other in the spaces between the macule. Interspaces depressed; mesopores abundant, aggregated in the macule, always closed at the surface, with gradually crowding horizontal diaphragms. Zocecial tubes with fewer diaphragms. True acanthopores wanting, but exceedinly minute tubuli, increasing in number with age, are to be detected in the interspaces by means of tangential sections. Type: C. florida Ulrich. Of this genus I am now acquainted with eight good species and three or four varieties that group themselves around C. florida. The earliest known occurs in the Pierce limestone of Tennessee. ‘This is very much like the Minnesota Trenton species next described, but as it has not yet been critically studied it may prove quite distinct. A variety of C. florida occurs in the upper Trenton beds at Nashville, Tennessee, and in Canada, and other varieties occur abundantly with the typical form of the species in the lower half of the Cincinnati rocks. C. fischeri Ulrich, is a Kentucky form from about the same horizon. In the upper part of the Hudson river group in Ohio, Indiana, Illinois and Wisconsin, we meet with C. polystomella Nicholssn, and C. limitaris Ulrich, and with two undescribed species at Wilmington, Illinois. This locality furnished also the types of C. parva Ulrich. These species are all separated easily from each other by means of intelligently prepared thin sections. CONSTELLARIA VARIA, 7%. Sp. PLATE XXI, FIGS .1-7. Zoarium consisting of one or more irregularly dividing branches arising from a broad basal expansion. Branches usually compressed, generally from 8 to 10 mm. wide, but varying between the extremes of 3and15mm. Maculw large, irregularly *1 consider the work of James and James referred to above as unworthy of such quotation, and that its citation among reputable works on the Bryozoa is to dignify it with an attention far beyond its deserts. But the possibility that others may be able to discover merits which I cannot may be sufficient @Xcuse for its inclusion in the bibliography. 312 THE PALEONTOLOGY OF MINNESOTA. (Constellaria varia. stellate, very slightly depressed or on a level with the general plane of the surface. The small clusters of zocecial apertures (four to ten in each) occupying the angles between the rays may be elevated a little above the level of the macule, but as a rule the entire surface may be said to be even. In a few cases however the maculz themselves are higher than the spaces separating them. “Zoccial apertures subcir- cular, inclosed by a very thin rim, and varying considerably in size, though approxi- mately equal on each fragment. Width of interspaces varying correspondingly so that about the same number of apertures occur in a given space in all specimens. .Ten or eleven occur in 3 mm. in the intermacular spaces, while the diameter of the apertures varies between the extremes of 0.15 and 0.25 mm. Figure 1 represents the surface of a specimen (x9) with small apertures and wide interspaces; fig. 2 a small part of another (x18) having comparatively large zocecial apertures and correspondingly narrow interspaces. The latter are always a little depressed, and, like the macule, occupied by the shallow yet distinct mouths of angular mesopores. Internal characters: Figure 4 represents a portion of a tangential section where it divides a mature zoarium immediately beneath the surface. In most sections the walls will be thinner and probably not show the minute tubuli in them as drawn in fig. 4. Series of sections prove that the relative width of the zocecial tubes and interspaces depends largely upon age, the width of the zoccia decreasing with maturity. Figure 5 is from a good vertical section, and shows that diaphragms occur in all the tubes throughout the zoarium, in the axial] region generally about twice their diameter apart, the distance between them becoming less as the zocecial tubes bend to the surface. In the mesopores, which are very abundant, especially when the section passes through one of the maculx, the diaphragms are at first rather far apart, but gradually become almost crowded at the surface. This species is nearer C. limitaris Ulrich, of the upper part of the Hudson river group, than any other. The superficial resemblance between them is very decided, but when we compare thin sections we find that the later species has smaller and much more abundantly tabulated mesopores. Indeed, the diaphragms are more numerous in both sets of tubes. All the other described species of the genus have smaller zocecia, and most of them differ in having no diaphragms in the axial region. None of the associated species are likely to be confused, none of them having stellate macule. Formation and locality.—Rather rare in the upper beds of the Galena shales near Cannon Falls, Minnesota. It is here associated with Orthis germana W and S., Homotrypa similis Foord, and several species of Nematopora. Mus. Reg. No. 8044, 8130. BRYOZOA. 313 Nicholsonella.] Genus NICHOLSONELLA, Ulrich. Nicholsonella, ULRICH, 1890, Geol. Sur. Ill., vol. viii, pp. 374 and 421. Zoaria consisting of irregularly intertwining flattened branches or fronds growing from an expanded base ; or of laminar, free or parasitic, expansions only. Zocecial tubes subcylindrical, with diaphragms only moderately numerous; apertures circular, “ enclosed by a slightly elevated papillose peristome. Interspaces wide, occupied by numerous angular mesopores more or less completely isolating the zocecia; minutely granulose in fully matured examples. Walls of both sets of tubes thin, and in the peripheral region traversed longitudinally by minute tubuli. With age a perforated calcareous deposit fills the interzocecial spaces in which the walls of the mesopores become unrecognizable. Mesopores with thicker and generally more numerous diaphragms than the zoccial tubes. In the axial region of transverse sections of the erect forms the tubes are very unequal. Type: N. ponderosa Ulrich, Geol. Sur. T1., vol. viii, p. 422, 1890. This is a Lower Silurian genus with rather uncertain affinities. So far as our knowledge goes the position of the genus in classification seems to be in a measure intermediate between Constellaria and Leioclema. In another direction we note considerable resemblance to Heterotrypa. The type is one of the earliest as well as one of the most complicated and interesting of the T'repostomata, and on the whole appears to occupy a rather isolated position with respect to contemporaneous types of structure. It is therefore unfortunate,that the preservation of the most typical species of the genus is almost invariably unfavorable for microscopic determination of their internal peculiarities. Indeed, it is a noteworthy fact, that Trenton speci- mens of Nicholsonella are but rarely as well preserved as are associated Bryozoa of other genera. N. ponderosa was described from the “Lower Blue” or sponge beds at Dixon, ulinois. A nearly related species occurs at Beloit, Wisconsin, and in the middle third of the Trenton shales of Minnesota. Associated with the latter is the laminar species, N. laminata, about to be described. N. pulchra is a fourth species from the “Pierce” limestone of Tennessee, N. vaupeli* is abundant in the quarries at Cincinnati, Ohio, as is an undescribed and closely related form occurring higher in the series at several localities in Ohio and Indiana. Finally, N. cwmulata is described in my Illinois work from the upper beds of the Hudson river group at Wilmington, Illinois. *Heterotrypa vaupeli Ulrich, 18838, Jour. Cin. Soc, Nat. Hist, vol. vi, p. 85. 314 THE PALEONTOLOGY OF MINNESOTA. [Nicholsonella pulchra,. NICHOLSONELLA PULCHRA, 2. Sp. PLATE XXI. FIGS. 8-12. Zoarium forming a bushy mass, consisting of irregularly divided, sometimes « anastomosing flattened branches, 6 to 10 mm. thick and 8 to 20 mm. wide, Surface with small conical or rounded menticules, subsolid at their apices, and frequently uniting on the rounded edges of the branches to form short ridges. In some speci- mens the monticules are very slightly developed. Zocecial apertures rounded, small, subequal, regularly arranged, about eleven in 3 mm., separated by interspaces nearly equalling their diameter—about 0.15 mm: Interspaces minutely papillose, generally depressed midway so that a rather irregular ring of papille surrounds each aperture. Mesopores, though completely isolating the zocecia, are to be detected at the surface only in young and weathered examples. Internal characters: In vertical sections the tubes diverge with comparative’ rapidity and uniformity of curvature. Their walls are thin, though not excessively so, and exhibit that lack of sharpness which characterizes especially the Trenton species of the genus. Young zocecial tubes arise in the axial region mainly and expand very gradually. Diaphragms occur throughout, two or three times their diameter apart in the axial region, and averaging nearly twice as many in a given space in the peripheral region. In young*examples it is not easy to distinguish the mesopores from the true zocecial tubes, but the solid deposit which more or less com- pletely fills up the outer part of the mesopores in the fully matured stages then renders the task an easy one. This deposit is lined vertically with rows of dots, and in many cases is divided up into two or more layers with light intervals between them. The two halves of fig. 10 show, in the upper, the structure of a matured example just beneath the surface. Here the zocecia are as usual not sharply defined and the inter- spaces completely filled with solid tissue in which a great number of small dots (representing the superficial papillz) are to be observed. At a deeper level in the zoarium (see lower half of fig, 10) the large angular mesopores aré open. Here even some dots (?acanthopores) are to be made out in the walls, chiefly at the angles of junction. Transverse sections show that in the axial region the tubes are of all sizes and variously angular. No dots like those seen in tangential sections are to be detected, but one of my sections exhibits fairly conclusive evidence of an intermittent struc- ture of the walls not unlike fig. 26 on plate 27. BRYOZOA. 315 Nicholsonella laminata.] There is very little likelihood of confusion between the present species and any other referred to the same genus, and thin sections will of course distinguish it at once from species of other genera. Among the latter Monticulopora arborea, from higher rocks, is strikingly like N. pulchra superficially. Formation and locality—Not uncommon in the ‘‘ Pierce limestone” at Murfreesboro, Tennessee, where it is associated with an abundance of fossils, chiefly Bryozoa. Mus. Reg. No. 8131. NICHOLSONELLA LAMINATA, 2. Sp. PLATE XXI, FIGS 15-19 and 21, Zoarium laminar, several mm. thick, the under side strongly wrinkled concen- trically. Upper surface even, but exhibiting rather indistinct macule or areas in which the interspaces between the zocecia are wider than usual. Zocecial apertures circular, regularly arranged, nine or ten in 8 mm., averaging 0.2 mm. in diameter and 0.13 mm. apart. Peristome thin, very minutely papillose. Interspaces occupied by angular mesopores forming a complete series between the zowcia. Mouths of mesopores closed or open. When closed the interspaces are slightly roughened by small granules among which a few of larger size (? acanthopores) have been detected. Internal characters as shown in figures. I have taken great pains to illustrate the internal characters just as they appeared to me under the camera lucida, and I refer the student to figs. 15, 16 and 17, rather than attempt a description. I will however admit at once that I do not understand the purpose of the system of dots lining the walls and radiating from the center of one of the zoecia. The latter may represent perforations in the diaphragms.* The surface and growth of this species remind one of species of Fistulipora with small zocecia. The laminar form of the zoaria will, it is believed, effectually distin- guish it from other forms of Nicholsonella. I know of no associated bryozoan with which it might be confounded, and the mere mention of caution should deter the student from carelessly classifying the Nicholsonella with the very different discoidal species of Prasopora and Mesotrypa. Formation and locality—Rare in the middle third of the Trenton shales at St. Paul and Min- neapolis. : *Such pore-like “dots” and other minute unexplained structures have been drawn carefully on a number of the plates attached to this work. Some day perhaps we may be able to appreciate their significance. In the meantime we must gather facts and I shall continue to delineate them as faithfully as I can. In this coanection it may be well to mention wha} many microscopists have long observed with dismay. Namely, that minute structures like those in question are gradually obliterated by some insidious action of the Canada balsam in which the preparations are mounted. It is therefore desirable, indeed necessary, to make the drawings as soon as possible after mounting the sections. 316 THE PALEONTOLOGY OF MINNESOTA. [Nicholsonella ponderosa? NICHOLSONELLA PONDEROSA ? Ulrich. PLATE XXI, FIGS. 13, 14, 20 and 22. *Nicholsonella ponderosa ULRICH, 1890. Geol. Sur. Ill., vol. viii, p. 422, pl. XXXIV, figs. 5-5d. Two specimens only of this form were found by the author at Minneapolis in the lower third or “Stictoporella beds” of the Trenton shales. One is an irregular mass, 65 mm. long by 30 to 40 mm. in thickness, presenting the bases of several large branches. The surface is not well preserved, but seems to have been considerably like that of N. laminata. The interior likewise is but illy preserved, and the illustra- tions (figs. 13 and 20) may be objected to on the ground that they are much more distinct than the sections. The “dots” in the interspaces have most probably been drawn too small and too numerous. It seems that two or three should have been united into one, giving an appearance more like fig. 10 of the same plate. Still, enough of the internal characters are to be made out to render the generic reference almost beyond dispute. On protected spots the surface is decidedly spinu- lose. Here about nine zocecial apertures occur in 3 mm. The other specimen is a fragment of a branch, about 11 mm. thick and 14 to 19 mm. wide. In the shape of the zocecia, their number in a given space, and in the charcter of the interspaces and interior, this specimen is apparently precisely like the first. There is nothing decidedly opposing the placing of these specimens with N. pon- derosa, the types of which are from the sponge-layer of the “ Lower Blue” limestone at Dixon, Illinois. Still, better preserved material is desirable before much confi- dence is to be placed in the identification. Family AMPLEXOPORIDA, Ulrich. Genus LEPTOTRYPA, Ulrich. Zoaria varying from thin incrustations to free forms of discoidal, spiral, or elongate conical shape; subglobose and irregularly massive species occur also. Zocecial tubes polygonal, with thin walls just appreciably thickened in the mature regions, and a variable number of diaphragms. Acanthopores small, more or less numerous, but almost invariably restricted to the angles of junction between the zocecial tubes. Mesopores wanting. Type: JL. minima Ulrich, of the Cincinnati group. This genus includes forms essentially like those of Amplexopora, Ulrich, only they arise into erect branching zoaria while the species of Leptotrypa never depart BRYOZOA. 317 Leptotrypa hexagonalis.] from the types of growth mentioned in the description, Numerous species of both genera are known and several of Leptotrypa from the Trenton beds of Minnesota, True Amplexopora, however, is first met with in the Utica.* LEPTOTRYPA HEXAGONALIS Ulrich. (Not Figured.) Leptotrypa hexagonalis, ULRICH, 1890. Geol. Surv. Ill., vol. viii, p. 455. Original description: “Zoarium forming parasitic expansions less than 1 mm. in thickness, spread upon Orthoceras and Hyolithes. Surface smooth. Clusters of cell apertures of almost twice the usual size are arranged in diagonally intersecting rows; these clusters are about 3 mm. apart, measuring from center to eenter. Zocecia regularly hexagonal in shape, sometimes a little elongated, seven, measuring longi- tudinally, almost nine, diagonally, in 2 mm.; diameter of the smaller 0.2, of the larger 0.35 mm. Acanthopores prominent on the surface when well preserved.” This species occurs almost invariably as a delicate lace-like expansion upon Hyolithes baconi Whitfield. This fact, together with the markedly hexagonal shape of the zocecial apertures, renders it an easily recognized species. Formation and locality.—Rather rare in the limestone at Minneapolis, Minnesota. The types are from equivalent beds (‘‘ Lower Blue”) at Mineral Point, Wisconsin, and Calhoun county, Illinois. Other localities are Janesville and Beloit, Wisconsin. Mus. Reg. Nos. 7551, 7557, 7595. LEPTOTRYPA INFORMIS, 2. Sp. PLATE XXVII, FIGS. 22 and 23. Zoarium forming parasitic patches or lump-like growths upon foreign bodies, varying considerably in size and from | to 5 mm. in thickness. At other times apparently free, with a wrinkled epitheca beneath. Surface without monticules, nor are the clusters of large cells very conspicuous except in a few cases where the zocecia forming them are separated by a limited number of small cells. Zowcial apertures polygonal, thirteen or fourteen of the average size in 3mm. Walls very thin, in vertical sections sometimes appearing as though made up of alternating horizontal bands of light and dark shades. Acanthopores more or less prominent at the surface, varying some in size, restricted to the angles of junction, one-half of which are occupied by them. Diaphragms complete, on the whole rather remote and irregularly distributed, the intervals between them varying from one to four times their diameter. *Trenton species have been placed under Amplexopora by both Mr. A. H. Foord and myself, but a re-examination has convinced me that the species in question are more likely aberrant types of Batostoma, where I would now place them, d 318 THE PALEONTOLOGY OF MINNESOTA. (Leptotrypa acervulosa. In many respects like L. semipilaris Ulrich, of the Cincinnati rocks, the most striking difference appearing in the number of the diaphragms, these being almost totally absent in that species. An undescribed species, differing chiefly in having much smaller and fewer acanthopores, occurs in the Galena shales. Formation and locality.—In the lower and perhaps also in the middle third of the Trenton shales at Minneapolis and St. Paul. Mus. Reg. No. 6024. LEPTOTRYPA ACERVULOSA, 2”. SP. PLATE XXVII, FIGS. 24 and 2. Zoarium occurring as small, irregular or subglobular masses, generally between 15 and 20 mm. in diameter and somewhat less in hight. Surface approximately even, but clusters of cells are conspicuously larger than the average, and in one case these are elevated into low monticlues. Zocecia angular, thin-walled, thirteen to fifteen, commonly fourteen of the usual size in 3 mm.; average diameter of aper- tures in the spaces between the clusters about 0.21 mm., of the largest in the clusters 0.85 to 0.4 mm. New tubes are interpolated in a great measure at cor- responding levels through the zoarium, so that immediately above and beneath such a level there may be considerable difference in the average size of the tubes. Dia- phragms from one to one and a half times their length apart except in the mature regions where they are separated by intervals about half as long. Acanthopores very small, in the angles, developed at intervals only, no trace of them being visible in some of the transverse sections. At the surface they are but rarely to be distin- guished. In a single example, however, many of the angles of junction are prom- inent and the walls between them crowned with a closely arranged row of minute papille. L. acervulosa agrees in most respects very closely with an undescribed species occurring at Clarksville, Ohio, in the upper beds of the Hudson river group. Smooth examples of L. (Monotrypa) irregularis Ulrich, also from Ohio, are likewise simulated, but that species is distinguished by having tubes practically without diaphragms. Two other species from the Cincinnati exposures, L. filiosa d’Orb., sp. and L. petasi- formis Nich., sp., are probably the nearest among described species. The first grows in large masses and has well developed monticules, while the second forms hat- shaped or hemispheric zoaria like Prasopora simulatrix. Formation and locality—Not uncommon in the Galena shales at Decorah, Iowa. A single speci- men from the same horizon in Goodhue county, Minnesota. Also in the shaly part of the Trenton at Burgin and Frankfort, Kentucky. Mus. Reg. No. 8060. BRYOZOA. 319 Leptotrypa claviformis,. ] LEPTOTRYPA CLAVIFORMIS, 7. Sp. PLATE XXVII, FIGS. 20 and 21. Zoarium growing around and beyond one or more segments of Arthroclema and Helopora into simple club-shaped forms varying from the smallest figured to one that is 28 mm. long and 1.5 to 2.5mm. in diameter. Some of the specimens have one or two short lateral branches, in which cases the supporting body was a twig of Arthroclema with lateral segments in place. Zocecial tubes growing about the axial body very much as in ordinary ramagse forms they grow about an imaginary center; diaphragms abundant except in the outer or direct portion; walls thin. Zocecial apertures subangular, nearly uniform in size, there being no appreciable clusters of large cells; without apparent arrangement, about fourteen in 3 mm. What may be mesopores, but more likely are merely young zoccia, are scattered among the ordinary tubes. At intervals, however, they seem to be more numerous than usual. Many, perhaps the majority, of the angles of junction are thickened and occupied by projecting acanthopores. In a general way, this species may be said to fall under Leptotrypa, but I am more than inclined to doubt that it belongs there. The interior of the speci- mens sectioned is but illy preserved, the finer details of structure being quite obscure. Some of the specimens remind of Petigopora, Ulrich, and it is here that better sections will probably cause us to refer them. Formation and locality.—Rather common in the middle and upper thirds of the Trenton shales at St. Paul and Minneapolis. Mus. Reg. No. 8132. Family CERAMOPORIDA, Ulrich. Genus SPATIOPORA, Ulrich. Spatiopora, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 155, and 1883, vol. vi, p. 166; Foorp, 1883, Contri. Micro-Pal. Cambro-Sil. Rocks, Can., p. 20;- ULRICH, 1890, Geol. Surv. Ill., vol. viii, p. 381. Zoaria forming thin parasitic crusts upon foreign bodies, the shells of Orthoceras being the most favored. Surface even or with monticules. Zocecia short, with direct and more or less irregularly shaped apertures. Lunarium scarcely perceptible even in thin sections. Mesopores very few, usually absent, when present occurring chiefly as “macul.” Interspaces often with large blunt spines (? acanthopores). Walls of zocecia moderately thin, with the characteristic structure pertaining to the family. Type: S. aspera Ulrich, 320 THE PALEONTOLOGY OF MINNESOTA. [Spatiopora labeculosa. Two Trenton species, S. areolata Foord, and S. labeculosa Ulrich, are referred to the genus with doubt.* The type, together with four or five other species, is found in the Cincinnati or Utica and Hudson river groups, above which the genus is not known to pass. SPATIOPORA LABECULOSA, %. Sp. PLATE XXVIII, FIGS, J and 2. Zoarium forming large and very thin expansions generally upon Orthoceras or Endoceras. Surface even, but conforming with the irregularities of the body grown upon. At intervals of 4 or 5 mm., measuring from center to center, there are clusters of cells decidedly larger than the average. These large apertures—they vary from 0.25 to 0.50 mm. in diameter—are arranged in each case about a sub- stellate or irregular, apparently solid, spot, which on closer examination proves to consist of closed mesopores. The extent of these spots varies greatly, some being almost 2 mm. wide, while in others the center is scarcely more than 0.5 mm. wide. Zoccial apertures subangular, usually a little oblong, with the margin on one side generally a little higher and more rounded than on the other. The last is true more particularly of the large cells which are not infrequently decidedly oblique and directed away from the center of the macule. In very young examples all of the apertures may be quite as oblique as in some species of Ceramoporella, but the lunarium is ever an inconspicuous feature. Many of the large cells again may preserve peculiar convex closures. Of the smaller or average zocecia eleven to thirteen occur in 83mm. Mesopores varying in number and distribution, but some- thing like the following rule seems to prevail. When the macule are large the mesoposes are few and of small size elsewhere (see figs. 1 and 2); when small they are comparatively more abundant in the inter-macular spaces. Internal characters: Figure 2 is a faithful copy of a portion of a tangential section prepared from a specimen (fig. 1 is an enlargement of its surface) having large macule. It will be noticed that the side of the zocecia nearest the macula is nearly always less angular than the opposite side. This fact is good evidence of the possession of an incipient or undeveloped lunarium. The minute structure of the walls, which is not the same as in Leptotrypa, is likewise indicative of ceramoporoid affinities. In vertical sections the prostrate part of the tubes is rather short, and the erect part, forming an angle of about 80° with the line of the surface, perhaps * Since this report was placed in the hands of the printer, two specimens of a typical species of this genus were collected by the author in the upper part of the middle third of the Trenton shales at Chatfield, Minn. The specific characters of these specimens, which grew over the shells of a small Orthoceras, are very similar to those of S. maculosa and S. lineata Ulrich, of the Cincinnati rocks, As a provisiona] designation for the form I would propose the name S. maculosa, var. incepta, BRYOZOA. a PAll Spatiopora fowensis,] never exceeds 1mm. Diaphragms are wanting in most of the tubes, but here and there the sections pass through one or several adjoining tubes having one diaphragm about midway up and sometimes another at the month. This is an interesting and easily recognized species. Of associated parasitic forms only two need be compared; one, Stromatotrypa ovalis of this work, has oval and much larger zocecia; the other is a rare and as yet undetermined form with circular and smaller zocecia, numerous mesopores, and more uneven zoarium. S. labeculosa differs from both in the greater size and distinctness of its maculie, and in the slight obliquity of its zocecial apertures. The macule will distinguish the species at once from all the other species of the genus. Formation and locality.—In the middle third of the Trenton shales at Minneapolis and St. Paul. Mus. Reg. No. 5026. ° SPATIOPORA IOWENSIS, ”. Sp. (Not figured.) Zoarium spread as an exceedingly thin crust over the cones of Orthoceras sociale Hall. Monticules wanting, but unusually distinct clusters of large cells are dis- tributed over the surface at intervals of about 5mm., measuring from center to center. Zocecia larger than in other species of the genus, their walls thin, the apertures nearly or quite direct, angular, often of hexagonal or rhombic shapes, with three of those in the clusters in 2 mm. and an average of nine of those in the spaces between the clustersin 3mm. Mesopores wanting except in the clusters mentioned where a few may be wedged in among the large cells. Many of the angles of junc- tion between the apertures are raised into sometimes small, at other times large, acanthopore-like prominences. In the dark shales at Graf, Iowa, this bryozoan is preserved as a thin gladiolus leaf-like film, the Orthoceras grown upon being compressed to such a degree that its original presence may not be suspected. This species is in every respect a true Spatiopora. The affinities are nearer S. maculosa Ulrich, of the Cincinnati rocks, than to any of the others, and it is with that species that I first thought to place it. On comparison however S. owensis proved to have larger zocecia, with eight to ten where the Ohio species has eleven or twelve. Formation and locality Maquoketa shales of the Hudson River group at Graf, Iowa, Mus. Reg. Nos. 7586, 7587. —21 322 THE PALEONTOLOGY OF MINNESOTA. (Crepipora. Genus CREPIPORA, Ulrich. Crepipora, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 157; 1890, Geol. Surv. Tll., vol. viii, pp. 380, 469. Zoaria incrusting, massive, or hemispherical; in one case forming regular hollow branches. Surface, especially in the first and last styles of growth, exhibiting at regular intervals macule of mesopores, appearing as minutely porous or subsolid elevations or depressions. In the massive forms these macule, to which the meso- pores are usually restricted, are very small. Zoccial tubes erect, their apertures very slightly oblique and varying from rhomboidal to subpyriform in shape. Luna- rium small and easily overlooked except in well preserved examples; best shown in tangential sections. Thin diaphragms are developed in moderate numbers. Type: C. simulans Ulrich. Eleven or twelve species, several as yet undescribed, are known to me having the characters ascribed to this genus. Three of these are Trenton, the rest, save an Upper Silurian species from Gotland, are Utica or Hudson River group forms. Crepipora differs from Ceramporella in having much fewer mesopores (typically none) in the inter-macular spaces, longer tubes, and less oblique apertures. C. epi- dermata Ulrich, from the Hudson River group of Illinois, is closely related to the new genus Bythotrypa, and ought perhaps to be referred to that genus, but it has seemed the wiser course to leave the species as originally described until special investiga- tions into the inter-relations of the Ceramoporide can be taken up. \CREPIPORA SUBHQUATA, 2. Sp. PLATE XXVIII, FIGS. 26-28. Zoarium a small laminar or incrusting expansion, 1 to 3 mm. thick. Zocecial apertures approximately direct, angular, often quadrate or pentagonal, of nearly uniform sizes on all parts of the surface, no distinguishable clusters of cells larger than the average having been developed; ten in 3 mm. Lunarium very slightly developed, the zocecial apertures and walls appearing much more like those of species of Monotrypa than of aceramoporoid. Tangential sections, however, (see figs. 26 and 27) afford more or less clear evidence of its presence, but it is rare to find more than one of the ends of the lunarium projecting inward from the wall. Many of the angles of junction are thickened and include an acanthopore-like structure. BRYOZOA. Oe Crepipora spatiosa. ] Mesopores very few. In vertical sections the walls are thin, with faint transverse lineation, and somewhat irregular. Diaphragms occur sparingly and at unequal intervals in the zocecial tubes, but in the mesopores which, being few, are not often seen, they are numerous. The absence of clusters of large cells and the greater average size of the ordinary zocecia will distinguish this peculiar species from associated Bryozoa having a similar mode of growth. Formation and locality—Rare in the upper third of the Trenton shales at St. Paul, Minnesota. CREPIPORA SPATIOSA, 7. Sp. (Not figured.) This name is proposed for a massive or heavy lamellate form that occurs in the Bryozoa layers at the top of the Trenton near Harrodsburg and Frankfort, Ken- tucky. It is closely related to C. hemispherica Ulrich (upper beds of Hudson River group in Illinois), on the one side, and C. perampla on the other. From the first it differs in the greater size and different shape of its zoarium, in haying thinner walls and fewer diaphragms, and less distinct lunarium. The second has larger zocecia and even less developed lunarium, but in other respects is very similar to the Ken- tucky species. Specimens of this species may attain a diameter of 300 mm. with a thickness of from 50 to 100 mm. Of the ordinary zoccia twelve occur in 5mm. Diaphragms 0.4 to 1.0 mm. apart. CREPIPORA PERAMPLA, 2. Sp. PLATE XXVIII, FIGS. 29-82. Three specimens have been seen of this. One, about 70 mm. in diameter and 33 high, is hemispheric, with the base concave and the margin flaring slightly. The others are larger (about 95 mm. in diameter) and, though worn, the basal part of the zoarium seems to have been convex instead of concave. Zocecia large, with very thin walls, genérally of angular shapes, the pentagonal and hexagonal more common than the subrhomboidal; those of the average size about 0.5 mm. in diameter, with nine or tenin5 mm. At intervals of 5 or 6 mm. clusters of tubes of more or less decidedly larger size than the ordinary are to be observed. Some of these may attain a width of 0.9 mm., but as a rule their size varies between 0.6 and 0.8 mm. Mesopores very few. 324 THE PALEONTOLOGY OF MINNESOTA. [Bythotrypa’ The appearance of thin sections is shown in the figures on plate XXVIII. In figs. 30 and 31 the presence of the lunarium is shown in an unmistakable manner, but fig. 32 is more like the usual appearance. Indeed, the lunarium is often so difficult to distinguish in transverse sections, that it is in order to caution the stu- dent against confusing the species with Monotrypa. In vertical sections the walls are often minutely crenulated, and in most cases exhibit the transverse lineation so common among the ceramoporoids. Exceedingly thin diaphragms occur in all the tubes at intervals varying from one to two tube-diameters. The great size of the zocecial tubes separates this species from all the other forms of Crepipora known. In this respect the species is approached by but one other paleozoic bryozoan, the Monotrypa magna of the present work, and both are believed to occur in nearly the same geological horizon. These two forms also present some points of resemblance in vertical sections, but so far as I can see there is really no relationship between them. In the Monotrypa the zocecia are much more regularly angular, their walls without the transverse lineation and more coarsely wavy, while a lunarium is of course never present. The C. hemispherica Ulrich, which seems to occur in the shales of the Hudson River group at Granger and near Spring Valley, differs chiefly in the smaller size of the zocecial tubes. Formation and locality—Trenton limestone at Chatfield and two miles northeast of Spring Valley, Minnesota. Mus, Reg. Nos. 151, 170, 211. Genus BYTHOTRYPA, n. gen. Zoaria massive or lamellate. Zocecia forming long continuous tubes, intersected by thin diaphragms, their walls minutely crenulate and with the structure charac- terizing the ceramoporoids. Lunarium well defined, large, projecting above the rest of the aperture margin. Mesopores numerous, open at the surface, interiorly form- ing a species of vesicular tissue unusually loose and irregular in construction. Type: Fistulipora laxata Ulrich. Largely increased collections of the type of this genus have convinced me that the species really belongs to the Ceramoporide. As none of the established genera of that family would include it, a new generic division became necessary. Bythotrypa is probably, as I regarded it at first, a type of structure that culminated in true Fistuliporide, but the lines along which the development progressed we are as yet unable to define. Still, it is more than possible that we have here merely a fore- shadowing of that family—in other words, a premature evolution of the fistuliporoid BRYOZOA. 825 Bythotrypa laxata.] type—that became extinct or was reabsorbed into the parent stock, failing to estab- lish a permanent line of development. In that case Crepipora? epidermata Ulrich, from the Hudson River rocks of Illinois, would seem to be the earliest known point in the direct line to Fistulipora. BytrHotrypPa LAXATA Ulrich. PLATE XXVIII, FIGS. 21-25. Fistulipora ? lawata ULRICH, 1889. Contri. Micro-Pal. Cambro-Sil. Rocks, Can., pt. ii, p. 37. Zoarium irregularly massive, usually beginning its growth upon some foreign body, the exposed under side strongly wrinkled and covered with an epithecal mem- brane. Specimens vary greatly in size, the smallest seen being about 12 mm. in diameter and 5 mm. or less high, while the Jargest is an oval mass 150 mm. long, 120 mm. wide, and about 70 mm. high. In the lower third of the Trenton shales they are all small, none observed exceeding 50 mm. in diameter. In the middle and upper thirds specimens between 75 and 100 mm. wide are not rare, but masses exceeding that size have been met with only in the upper part of the Galena shales. Zocecial apertures subovate, nearly equal, direct or a little oblique, the lunarium broad, sharply elevated, sometimes seeming to arch slightly over the aperture; their arrangement appearing more irregular than it is, with nine or ten in 5mm. Meso- pores abundant, varying greatly in size, a few quite as large as the zocecia fronr which they are distinguished by their more angular and irregular form and in being without a lunarium. Mesopores forming larger or smaller clusters at irregular intervals from which the zoccial apertures are turned ina radial manner. These clusters are most inconspicuous—even difficult to make out under the glass—except under certain conditions of weathering when they stand out as subsolid spots. Under ordinary circumstances the whole surface seems to be occupied uniformly by an irregular network of cells. Internal characters: In transverse sections the appearance, aside from an unusual irregularity and looseness of arrangement, is much as in species of Fistulipora. The zocecia are irregularly pyriform or ovate in cross section, and have thin walls. The lunarium, though often not a very marked feature, is still always determinable by the more regularly curved semi-circular form of the lunarial side of the circumfer- ence of the zocwcium, the opposite side being, if not angular, at any rate always drawn to a circle of greater diameter than the lunarial side. Occasionally one or both ends of the lunarium may project into the zocecial cavity (see fig. 25). Not infrequently also the lunarial side is thickened by a light-colored deposit upon the 526 THE PALEONTOLOGY OF MINNESOTA. [Anolotichia. outer side in which very fine transverse lines may be noticed. Dimensions of zocecium of average size, about 0.3 by 0.4 mm. Interstitial cells varying greatly in size and distribution, some being very small, others as large and even larger than the zocecia. They form generally but a single series between the zocecia, yet it is not uncommon to notice a double row for a short distance. An obscure radial arrangement, with the zocecia in contact lengthwise, is noticeable about certain points, 6 mm. or more apart, where the interstitial cells are more numerous than elsewhere, without, however, at any time being in sufficient numbers to justify being called “ macule.” Vertical sections are even more characteristic, since in these the loose construc- tion mentioned is very striking. The zocecia appear as long irregular tubes crossed at variable intervals by exceedingly delicate horizontal diaphragms. The average distance between the diaphragms depends somewhat upon the horizon from which the specimen was collected. In zoaria from the lower and middle thirds of the Trenton shales, the average is between 0.5 and 0.9 mm., but in those from the Galena shales it is between 0.8 and 1.2mm. The interstitial cells assume all sorts of shapes, but are always extremely high. A tendency to arrange themselves in vertical series is usually manifest, but they cannot be said to form tabulated tubes, their walls being on the whole quite irregular and the end partitions more or less oblique and in many cases overlapping. All the walls have that peculiar granular structure noticed, in paleozoic Bryozoa, only among the Ceramoporide and Fistuliporide. Both the external and internal characters of this species are so distinctive that there is little or no danger of confusing it with associate massive forms. Formation and locality——Not rare in the three divisions of the Trenton shales at Minneapolis, St. Paul and Cannon Falls. It reappears, larger than ever, in the upper part of the Galena shales at several localities in Goodhue county, Minnesota, and at Decorah, Iowa. The original Manitoba type of the species I now believe to have come from strata equivalent to the last. It was collected at St. Andrews. Mus. Reg. Nos. 5963, 7602. Genus ANOLOTICHIA, Ulrich. Anolotichia, Ulrich, 1890. Geol. Sur. Il., vol. viii, pp. 381 and 473. Zoaria large, irregularly ramose or digitate. Zocecia comparatively large, form- ing long prismatic tubes, intersected by complete diaphragms more or less remotely situated. Walls thin, appearing transversely lineate in vertical sections. Apertures angular or subovate, direct, with a distinctly elevated lunarium. Thin sections show the lunarium to be traversed lengthwise by from two to seven minute, closely tabu- lated tubes. Mesopores very few in A. impolita, but moderately abundant, rather equally distributed among the zocecia, and of irregular form, in the type species. BRYOZOA. Sei Anolotichia impolita.] Type: A. ponderosa Ulrich, Hudson River group, Wilmington, Illinois. Only two species, the type and the one next described, are as yet known of this remarkable genus. Aside from the lunarial tubuli, which constitute the principal distinctive character, the genus corresponds rather closely on the one hand, through A. impolita, with Crepipora, and fully as well on the other, through A. ponderosa with Chiloporella. In the absence of any positive knowledge concerning the functions and classificatory value of the lunarial tubuli, the relationships noted must provis- ionally determine the systematic position of Anolotichia as intermediate between those genera. Anonoricu1a impotita Ulrich. PLATE XXVIII, FIGS. 15-20. Crepipora impolita ULRICH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Sur. Minn., p. 77. Zoarium large, bushy, consisting of abundantly and irregularly divided solid branches, the latter varying from 5 to over 20 mm. in diameter. At the base the branches may coalesce, and here they are always stronger than at their termina- tions. Rarely the zoarium is not branched but occurs as an irregular mass with ‘lobe-like excrescences. Zocecia large, with moderately thin walls, direct, hexagonal or subrhomboidal apertures. The latter are subequal (there being no distinguish- able clusters of large ones), are arranged in rather regular series with eleven in 5 mm. Lunarium well developed, appearing as a small crescentic elevation usually in one of the angles. Mesopores few, sometimes appearing to be absent entirely; occa- sionally forming small clusters of from two to six. Internal characters: Yn tangential sections the walls of contiguous zocecia appear to be thoroughly amalgamated; the lunarium is represented by two or three small lucid spots (lunarial tubuli) on one side of the tube, the end ones projecting slightly into its cavity. In vertical sections the tubes are scarcely to be called vertical even in the axial region, curving outward with a uniform curve from the beginning. Their walls are composed of rapidly alternating dark and lighter shades of schlerenchyma, so that they appear more or less distinctly lineate transversely. The cause of these lines, which are closest in the peripheral part of the zoarium, is unknown, unless the light ones, which are of uniform width and, especially in the axial region, narrower than the dark bands, represent rows of perforations. Exceed- ingly delicate diaphragms, their diameter or more apart, occur chiefly in the outer and middle parts of the tubes. The axial portion of transverse sections is very nearly like tangential, the only difference being that the walls are a little thinner and small tubes comparatively more abundant. 328 THE PALEONTOLOGY OF MINNESOTA. (Ceramoporella. The much smaller number of mesopores is the most obvious external difference between the present species and A, ponderosa Ulrich. The lunarial tubuli also are about twice as numerous in that species. Of Minnesota species, | know of only one that is likely to be confounded. This is the Batostoma magnopora, a rare species of the middle third of the shales (Rhinidictya beds), having, if not always monticules, at least conspicuous clusters of large cells. The absence of such clusters in the Anolotichia renders the separation of the two forms comparatively easy after all. Formation and locality.—This is a very abundant and highly characteristic fossil of the lower third of the Trenton shales at St. Paul, Minneapolis, Cannon Falls, Chatfield, Lanesboro and Fountain. Mus. Reg. Nos. 5958, 5962, 7660. Genus CERAMOPORELLA, Ulrich. Ceramoporella, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 156; Geol. Sury. Ill., vol. viii, pp. 380, 464. Zoaria incrusting, often becoming massive by the superposition of numerous thin layers. Zocecial tubes short, their walls thin. Apertures more or less oblique, hooded, commonly of oval shape. The hoods are directed away from the centers of small macule marking the surface at rythmical intervals. Mesopores abundant, often completely isolating the zocecia, their apertures usually open, sometimes closed by a thin membrane. Diaphragms only rarely present. Type: C. distincta Ulrich, Cincinnati group, Ohio. This genus embraces all the parasitic Lower Silurian ceramoporoids, The species, with few exceptions, are all closely related, and some of them seem also to have an unusually extended vertical range. Thus the first of the following Minnesota species, which occurs here in the lowest member of the shales, is so much like the Cincinnati types of the genus that I cannot distinguish them. C. inclusa is a well marked species, and unknown above the upper third of the Trenton shales, but the Galena shales species, CO. interporosa, n. sp., 1s likewise a common form throughout the lower 300 feet of the rocks at Cincinnati, Ohio. CERAMOPORELLA DistincTa Ulrich. PLATE XXVIII, FIG. 13. Ceramoporella distincta ULRicH, 1890. Geol. Surv. Ill., vol. viii, p. 464. Zoarium forming thin parasitic patches upon other Bryozoa, the Minnesota speci- mens seen consisting of but a single layer less than 0.7 mm. thick. Zocecia small, ° radially arranged about certain small macula, nine to eleven, measuring obliquely, BRYOZOA. 329 Ceramoporella inclusa.] in3mm. Apertures very oblique, with an overhanging hood, highest posteriorly. Mesopores numerous, small, usually forming a single linear series between the sides of the zocecia, This species is much rarer than the associated C. inclusa from which it is at once distinguished by its smaller and differently shaped zocecial apertures. In C. interporosa the apertures are larger and more direct. Formation and locality—Lower third of the Trenton shales at Minneapolis and St. Paul. It is met with next in the Cincinnati rocks, being an abundant species at that locality. CERAMOPORELLA INCLUSA, ”. SP. PLATE XXVIII, FIGS, 8-11. Zoarium forming thin crusts over foreign bodies, not observed to consist of more than a single layer, less than 1 mm. thick, generally 20 mm. or more in diameter. The customary macul, about which the zowcial apertures are arranged in a radial manner, are represented, but less distinctly than usual. Nor is the radial disposition of the apertures as marked a feature as usual. Indeed, it is common to find, as shown in figure 8, all of them turned toward the nearest margin of the zoarium. Zocecial apertures oval, occupying, with three mesopores, the bottom of subtriangular or rhomboidal, obliquely depressed spaces. One of these mesopore-pits is in front, the second and third on the sides of the true aperture, the posterior side of the latter being formed by the strongly elevated lunarium which in this species is an unusually prominent feature. Arrangement of apertures only moderately regular, eight or nine in 3mm. ; Numerous deviations from the above described normal characters of this species are shown in the abundant material before me. Most of them are due to imperfect preservation and irregularities of growth, and all of them are of a nature that can be interpreted successfully only by extended study of specimens. The inclusion of each zoccial aperture and mesopores in a subtriangular en- closed space, and the strong development of the lunarium are distinctive for the species. These features are less constant in what I presume to be a mutation of the species (toward the Cincinnati group C. ohioensis Nicholson) occurring in the upper third of the Trenton shales. Formation and locality—Common in the lower and middle thirds of the Trenton shales at Minneapolis, St. Paul, and various localities in Goodhue and Fillmore counties. Rare and less typical in the upper third of the shales at St. Paul and Cannon Falls. Mus. Reg. Nos. 7624, 7656, 7661, 7662, 8380. 330 THE PALEONTOLOGY OF MINNESOTA. (Ceramoporella interporosa. CERAMOPORELLA INTERPOROSA, ”, Sp. PLATE, XXVIII, FIG. 12. All the Minnesota examples seen are thin crusts upon foreign bodies, but in the Cincinnati rocks the species often forms large masses by superposition of numerous layers. The zocecial apertures are larger, more direct, and comparatively wider than in C. distincta Ulrich, with an average of ninein 3 mm. Fig. 12 represents the usual appearance of the surface. Sometimes the lunarium is better distinguished from the rest of the posterior hood than shown in the figure. The mesopores are always numerous and generally more equally distributed around the zocecia than in other species of the genus. Formation and locality.—In Minnesota the species has been noticed only in the Galena shales of Goodhue county. At Cincinnati, Ohio, the same species apparently is not uncommon in the lower 300 feet of strata. Mus. Reg. No. 7647. Genus DIAMESOPORA, Hall. Diamesopera, HALL, 1852, Pal. N. Y., vol. ii, p. 158 (not defined); Pal. N. Y., vol. vi, p. xv, 1887: ULRICH, 1890, Geol. Surv. Ill., vol. viii, pp, 380, 467. Celoclema, ULRICH. 1882. Jour. Cin. Soc. Nat. Hist., vol. v (not defined). Zoaria ramose, branches hollow, lined internally with a striated epitheca. In other respects very much like Ceramoporella and Ceramophylla. This name stands for an easily recognized division of the Ceramoporide. The genus may be more convenient than natural, yet I must confess that the evidence so far gathered points rather to an opposite conclusion. The species next described is the earliest known. Several occur in the Cincinnati rocks, but it is not till we come to the Niagara that the genus has its greatest development, both in the way of species and individuals. DIAMESOPORA TRENTONENSIS, ”. Sp. PLATE XXVIII, FIG. 14. Zoarium consisting of small hollow branches varying from 1.5 to 3.5 mm. in diameter; thickness of zoarium 0.4 to 0.8 mm.; axial tube varying in diameter, the epithecal lining not observed. Small maculwe sometimes present. Zocecial aper- tures oval, about their diameters apart, arranged sometimes regularly in diagonally intersecting rows, at other times as shown in fig. 14; averaging nine in 3 mm. When regularly arranged they are set into obliquely depressed subrhomboidal areas, BRYOZOA. 381 Ceramophylla.] reminding of Ceramoporella inclusa (see pl. XXVIII, figs. 8-11). The lunarium, how- ever, is never prominent as in that species, nor is the posterior border of the aperture elevated as much as is usual among Lower Silurian ceramoporoids. Mesopores two or three to each zocecium, placed indiscriminately among the larger apertures or one on each side and a third in front of the zocecial orifice. This species is closely related to both D. vaupeli and communis Ulrich, of the Cincinnati group of Ohio, but it is clearly not identical with either. In the first place the Trenton form is always smaller, so that they may be distinguished at once by the matter of size alone. Then the lunarial rim is not so high and the arrange- ment of the mesopores and other superficial parts generally a little different. Formation and locality—In the upper third of the Trenton shales, and in the Galena shales at St. Paul and Cannon Falls. Also in the Trenton limestone at Trenton Falls, New York, and Ottawa, Canada. Genus CERAMOPHYLLA, n. gen. Zoaria erect, bifoliate, the two layers grown together back to back; in other respects like Ceramoporella and Diamesopora. Type: C. frondosa, n. sp. The leaf-like zoarium of the only species of this genus known, is in many respects very much like that of Rhinopora, Hall. Still they are very different struc- turally, and I am satisfied that the relationship between them must be quite remote. On the other hand, Ceramophylla may be justly called a bifoliate Ceramoporella, just as Diamesopora would be a ramose one. CERAMOPHYLLA FRONDOSA, 7. Sp. PLATE XXVIII, FIGS. 3-7 Zoarium arising from a small basal expansion into erect, leaf-like, undulating fronds, celluliferous on both sides ; thickness varying from 0.5 to 2.0 mm., but aver- aging less than 1 mm.; largest frond seen about 40 mm. high; margins rounded, exposing the mesial lamine. At intervals of about 3 mm. the surface exhibits more or less conspicuous, substellate maculw of mesopores. Zocecial apertures ovate, oblique, the posterior margin well elevated, arranged more or less regularly in transverse and diagonally intersecting series, with about eight in 3 mm. Mesopores one, two, or three to each zocecium, variously arranged, often irregularly distrib- uted. Inthe most regular and normally developed examples the zocecial apertures 332 THE PALEONTOLOGY OF MINNESOTA. (Ceramophylla frondosa. are ovate or pyriform and narrowest and highest behind, while in front of the depressed anterior side of each there is either one large triangular mesopore or three small ones, the whole in each case being contained in an obliquely concave rhomboidal space. j Of internal characters it is sufficient to say that diaphragms are wanting, the primitive or prostrate part of the tubes thin-walled and in most cases longer than the erect portion. In the latter the interspaces are very thick and, in vertical sec- tions, crossed obliquely by dark lines. OF associated bifoliate Bryozoa only Hurydictya multipora grows into broad fronds. But the merest tyro in the science must find the task of identifying the Ceramophylla an easy one. Formation and locality.x—Over one hundred examples were collected at St. Paul in the upper third (Phylloporina beds) of the Trenton shales. It is rarely met with in the same beds in Goodhue county. Mus. Reg. No. 8381. Nore:—In the preceding report on the Bryozoa the author has adopted a merely provisional nomenclature of the divisons or beds into which the Trenton formation of Minnesota is divisible, partly upon lithological, but more especially upon paleontological grounds. ‘This is in accordance with an agreement among the several authors at work on the paleontology of the Lower Silurian rocks of Minnesota. We believed, namely, that it was best to defer the adoption of permanent names for the faunal zones till the study of all the classes had been completed. The subject, therefore, will be found treated in a comprehensive manner in the introductory chapter to the volume. In that chapter a full list of the Trenton and Hudson River fossils found in the state is given, and each is referred to its proper horizon in the series. PLATE I. Big. Vtord: WVINELLAURIEPENS sUITICI:..orcisisitere aeele ctey eros ree ere ee eee ee te oree Rae e eee eee 1. Two colonies attached to the inner side of a ventral valve of Strophomena septata W. and S.; natural size. 2. Portion of one of the colonies magnified X18. The pores are absent, probably not having been preserved. 3. Another portion of same zoarium X18, showing a nucleus with five divisions of the tubular stolon radiating from it. This portion of the specimen also preserves some of the pores marking the points where the zowcia were attached. 4. Another specimen attached to a fragment of shell; natural size. 5. Small portion of same, 18, with three tubes lying parallel with each other. The longi- tudinal lines are stronger than usual. Upper third of the Trenton shales at St. Paul.* Higss6andi7-ee SLOMATOPORA, DENUISSIMA MUI EICH ty cece ccieeerincte meeieteieis eerie ieiea sic crererele steisiaieietenmemteratele 6. Portion of zoarium, 9, showing its slender zocecia and mode of growth, Utica horizon, Cincinnati group, Cincinnati, O. 7. Several zocecia of same 25, to show their apertures and form more clearly. HiZS. SitOMlLZques LOMATORORA PROUDANAYS Aly Mill Creme ite eteterctenistsrecucielsleleleleiste bis e)sretenets erates siete aleiete 8and 9. Zoarium natural size and portion *9. 10. Several zocecia of same, *25. ; 11. Several zocecia of same colony, a little more slender than usual, *25. 12. Several cells of a form of this species in which they are unusually large, *25. (Survey Museum. Reg. No. 5926.) Middle third of the Trenton shales at Minneapolis and St. Paul. Migs, 1302] iS TOMATOPORA UNE TATA ELallllls rstctousefecrereisioc eine ois cricteicinissteid) vtrele ote = clereicieielemisysi cnet isiotele 13 and 14. A colony attached to inner side of a fragment of shell, natural size, and a portion of same x9. 15 and 16. Another colony, natural size and a portion 9, . 17. Three zowcia of same, X18, one of them preserving traces of the minute pores that pierce the wall. 18. Vertical section of one cell, X18. Upper third of the Trenton shales at Cannon Falls, Minn. 19. Small portion of a large colony, *9, growing upon the concave side of Lepteena alternata; Cincinnati hills. 20. Two zoccia of same, x18. In the Cincinnati form of this species the zowcia are more inflated, and the whole zoarium more compact, and the growth more luxuriant than in the typical Trenton form. 21. Several zocecia of another Cincinnati specimen, in outline, *18, showing the unusual condition of three ‘‘gems” springing from one parent cell. Higgs; 22;ands23) STOMATOPORA TURGIDA IU Chi-. 5 sec cee uae eleteie cere eeu stsheererenis te ereisipls RANG ish Acie An example of this species growing upon Pachydictya splendens Ulr., natural size and same 9. Upper beds of the Hudson River gr., Wilmington, Il]. This species was recently discovered in the lower part of these beds in Fillmore county, Minn. Wiga24 a PROBOSCENAUEUM UE OS At IIS Permittee eieteelemeenetsrer utter ete sieietetfetoreretel ete yetetetsli /atatcunie tales oYayoval aateteretetere An example of this species, natural size and portion x9. Upper third of the Trenton shales, St. Paul, Minn. Figs..25 to'27. JBERENICEA MINNESOTENSIS: UITICHe me ccleele ie ccc sic o> os or epee sleeise snc sae! Jeveisie aisle\s edie 25 and 27. Two specimens of the natural size. Near Minneapolis, Minn. The original of fig. 27 belongs to the Survey Museum. Reg. No. 5925. 26. (29 on plate) Portion of original of fig. 25, x9. (See also Plate IT). Mig126.) ER OBOSCINASERONDOSA (NICHOLSON) ye aielefeletaatetetetetaie letersi istede ete rosie 'slefaie'e 192 About three fourths of a segment of this species, x18. Middle third of the Trenton shales, Minneapolis, Minn. Itis within the possibilities that these segments may belong to the tertiary set of Arthroclema striatum Ul. i oe OSE OR OR AWMU CR ONUAUA Sy UIT etere reteset a atemete re totet ie ieletyatetce fects lohn/olaperstetcfemeiet= aicietetsieheteleleleleae aicls/alel-yetaiare 193 A segment of this form natural size, and the greater ‘part of it x18. The specimens upon which this species is found may prove to belong to Arthroclema armatum Ulr. Upper part of Galena shales, near Cannon Falls, Minn. Migs WG bOM ey EET O POR ACCA RIS 1 i ALN CS ie terererctoyeterstefeletsietevsvevelere iets tate totes telaobetersttetomelaleletivetatel=,ctefoyiaia(aleteierats 195 ll and 12. Two segments, natural size and X18. lla. Portion of original of fig. 11, x50. 11b. Transverse section of a segment, X50. Hudson River group, Waynesville, Ohio. Figs. 13 and 14. ARTHROSYLUS CONJUNCTUS Ulr...... 0.6.23. cece cece tence Brae oral Yaseseses ee av eneseee b 188 13. Lateral view of the central portion of a segment, “18. s 14. View of small portion of non-celluliferous side of same, *18. Trenton shales, near Fountain, Minn. Mics el bland eG ee ARTE OST US OB TLE) UU pm) Ui stavererey-fekede retell steiateisenettstetetertaeiaieteltotetteratatateietctoteioneteleteantetela 188 Two views of a segment of this species, X18, in the first showing the non-celluliferous side with the upper extremity and about three-fourths of the length, in the second the central portion turned so as to show the lateral aspect. Lower third of the Trenton shales at Minneapolis, Minn. Beneath fig. 15 a small figure is erroneously marked with the number 16. This repre- sents a transverse section of the type of the genus A. tenwis (James), from the lower part of the rocks at Cincinnati, Ohio. igs iho 20s) ONE NCA TOP ORIA GGHVAN OSA SIUM ocjerstes morete east ited itera telat ie creicvelere fusiols lene iste aieyeltaiet are ete 205 17. Portion of unbranched fragment, *18, showing the granulose angles and interspaces, and narrow zocecial apertures; the latter i in five rows. 18. Bifurcating fragment, *18, with the rows of granules slightly flexuous. 19 and 20. Portion of slightly worn fragment, and end view of same, *18. This has only four rows of zooecia. Upper part of Galena sbales, near Cannon Falls, Minn. NOS 22160 2osey INEINCALTO POR AU CONTE: Aa Ollie tate fe cteneyeitlatereleeloterarheieletemateyerale otek attelolatetetepaietele ere leliet=te otatelststets 206 Zoarium of this species, natural size, <9, and portion of same *18. Upper part of Galena shales, near Cannon Falls, Minn. MCS p24 Anya). peNIEE MAC OP ORAS Oj VPAIETS AU) Ilveeanelotreetar tated ott tetete bets reretere teteteyet-teteretalal stole scott jelerstatetierey sts tar teke iene toe ke 204 Two fragments of this opecies, natural size and x18, the first with four rows of zooecia, the other with five. Upper part of Galena shales, near Cannon Falls, Minn. Wigs s2Grandi2h NEMA ORO R ANI HIG LC AT OIG Wii terorete Metety slate ajeletelelorolalelalaleratsleielelestsieleteteierst= eiciatel teietal eietaeeys 206 Two fragments of the exceedingly delicate zoarium of this species, natural size and x18. Upper part of Galena shales, near Cannon Falls, Minn. Migs 28ib0ido. CAR LOR OCLE MAL SUR LAM UIMarI iS]: 5 tersvelejalerstetetsazelelsreiieteverelcte sielotere miisrsinieretetestecel sterafetatetareserots(ateiy 198 28. Puma segment, natural size and X12, with a large articulating socket and expanding ends. 29. Lower end of same, X18. 30 and 31. Lateral and end views of a large and strongly striated primary segment, natural size and X18. The zoocecial apertures are incorrectly represented in this figure. (See correction p. 199, sixth line from top.) 32 and 33. Two segments of the secondary set, natural size and X18. One has five cycles of zoccia and an articulating socket, the other six cycles and no distinguishable socket. (See also plate IT.) Middle third of the Trenton shales, Minneapolis, Minn. Higstot, GARTHROCL EMA: CORN UM UMW llietrartstsrstetcione siete! ele relelaletsletalensiereieloustetete lalate: «femtin dere voletate temas iaseiehel tates tere 200 ‘View of upper end of the segment represented by fig. 18 on plate II; x18. Figs. 35 to 37. ARTHROCLEMA, Sp. undet............cceeee eens ronondEoadsde Usgamidy SobpcbboO bean ode 203 35. Slightly abraded segment, natural size and X18. An obscure, subcentrally situated, articulating socket is distinguishable. 36 and 37. aye internal casts of the zooscia, X18, showing their spiral arrangement in the segmen Uiper third of the Trenton shales, St. Paul, Minn. = SLORTES UO RVEMEORMIN VES OAS (Silurian Bryozoa.| PRA t Wb iva NW AY CA Gy __ fi aa Tis aa “ cn , Koi ~s iaawe r : £9 Ce ee ES BE PROMO. Le ee ut weit \ (ez a af PM hed ee Oo ie ue va Wi rst het Se a: Ye Piste) : rtf ia whe if Beebe eae PLATE IV. Rigs sLibo rps. PHYEEOPORINATS UB LAUXCAN WNL IUD ere serrate asi sianielcleratetncia steisserefarateveystarstelorclalarsietevale sisters eieietsie terete 209 land 2. Reverse side of small fragment, natural size and portion of same x9, showing striated character of this side in young or exfoliated examples. Lower Trenton lime- stone, Minneapolis, Minn. Survey Museum. Reg. No. 5954. 38and 4. Another fragment from the same locality, exposing the obverse side, natural size, and portion of same *9. 5. Tangential section, 18, showing appearance of zocecia at varying depths. 6. Two transverse sections of branches, <18. 7. A rather loosely woven frond from the ‘‘Glade” limestone at Lavergne, Tenn.; natural size. Migs: 8itod4. Ver yvAGLOPORUGA RW DICT GATAS (EDAD) i acres reve cp tnersisleleletatereis kale alevetstcreraeseieteteielrele nies elalereeearetse 210 8. A frond exposing the reverse side, natural size, Minneapolis, Minn. . 9. Portion of same, <9. 10 and 11. Another fragment from the same locality, natural size and x9. 12. Small fragment, likewise from Minneapolis, exposing the obverse face, *18. 13 and 14. Obverse and reverse sides of two fragments obtained from washings of Galena shale at Cannon Falls, Minn.; <18. 15. Tangential section, *18, of an example from Trenton Falls, N. Y. Hi gS> 16) bor eee evar FOP ORTNIAGEDAU TE MU reper taretorafelarctelafeoctstotshotetolatststatelstanletelatetateletoteetstarstet state cteteteter-ietai senate 211 16, Reverse side of aspecimen, natural size, showing irregular arrangement of fenestrules. 17. Celluliferous side of another fragment, natural size, showing the irregular solid swellings. 18. Surface of same, <9. 19. Reverse side of same, *9. 20. Tangential section, <18, cutting the zocecia just beneath their mouths. 21. Another portion of same section, 18, where it divides the zoarium at a deeper level. Upper third of the Trenton shales at St. Paul, Minn. BED DDE ABN Bary WEY RNG UO CYED RC SOR YC DP ONT SS DAP, Bryozoa > Vol. LT. Jab IMG EO. «C.S.del. et Lith The Henderson Achert Lith.Co Cin.O an) T Brine dpe ett te oot ig ened: Taira fice et Eee Anaad ne PLATE V. Figs. 1 to 10. PHYLLOPORINA CORTICOSA UIP.... 1.2. 0s. ee eee eee tener e eet terete eee ene eens 212 1. A frond of this species exposing the poriferous or obverse side; natural size. 2and 6. Reverse side of a fragment, natural size and a portion “9. 3and 7. Obvyerse side of another fragment, natural size and a portion <9. 4and 5. Two specimens of the basal portion of the zoarium, natural size. 8. Tangential section, X18, cutting the zocecial tubes at varying depths from the surface. 9. Transverse section of several branches, 15. ; 10. Vertical section of a branch, <18. Upper third of the Trenton shales, near Cannon Falls, Minn. Figs ll and 12. MRHINIDICTYA GRANDIS, N. SP......-- ses eee ee eee eee e eee teen ence tees twee cece 136 A fine example from the ‘Lower Blue” limestone at DixonII1., natural size and a portion x9. (See also Plate VI.) Figs. 138 to 18. RHINIDICTYA MINIMA Ulr..............-...- gos einibie fiee/6\a\e\sfelele nisinin/sjn\s/eleislnibialeis/a aloisic/sisiel= 132 13. Three fragments of the natural size. 14and 15. One of them x9, and a portion of same <18, showing the small zooscial apertures and grano-striate character of the interspaces. 17. Tangential section of the variety MODESTA, X18, showing the appearences of the zowcia at various depths beneath the surface. 18. Tangential section of the typical form of the species, *18. Upper part of the Galena shales, near Cannon Falls, Minn. Wigs. 19 to 21. REINIDICTYA PAUPBRA UlP.. 2.00.0 csc c cece eee ee ees came teenies cence cena cieiele 129 19. A nearly complete specimen, natural size. 20and 21. A fragment, natural size <9 and X18. Upper third of the Trenton shales, St. Paul, Minn. Figs. 22 to 25. RHINIDICTYA NEGLECTA DN. SP... eee. ee eee cee eee cette te eee e eet teen eee e eens cees 130 22. A fragment of the natural size and a portion X18, showing the usual characters of the species . 23,24 and 25. Respectively, trarsverse, vertical, and tangential sections of a specimen wider than the original of fig. 22, but agreeing in all other respects with it. Trenton limestone near Danville, Ky. GEOMO GLCAUMW DY ACM AM AHO S LOREES URC @O FMI NES O06 {( Bryozoa.]) \ nesestes qteadeoteee “ghetece asagalesegat E.0OU «C.S.del et Lith The Henderson -Achert Lith Co. Cin.0 ap i PLATE VI. All the figurers on this plate except No. 18 are X18. RASS SIO 2ianGs Lo. RAEN ED LO DAN NTO DA Tats ml Merpaletets tolalolejereleisiofeteler={-lelal=jateie[everstaleiaplstalclateleleioeietateye 125 1. Tangential section of an old and thick example of the usual form of this species. Figs. 6 and 12 represent transverse and vertical sections of same. 2and 38. Tangential and vertical sections of a fragment of the var. SENILIS (see p. 127), showing the great abundance of the median tubuli and the structure of one of the solid spots. 4and5. Tangential and vertical sections of a well preserved and typical example. 6. Small portion of a transverse section prepared from the same specimen that furnished the originals of figs. 1 and 12. 12. Vertical section of a thick specimen. (See figs. 1 and 6). Only one side of the zoarium is entirely represented. 13. Tangential section of a young example. For the external characters of this species see plate VII. Middle third of the Trenton shales at Minneapolis and St. Paul. TS e er eANG Saye LVELLEN ELD CD Weta GROUT ROTTS aU) lite aye iene stelaystetnpete) lel attate(sfuteratelals]stctatatataent=teleitetste > ‘ ave 7S ; 5 - “aie a + a ’ . “ ni d intl iH rast Sree peop Uy ure ry a8 ‘ 0 AL rt asia ela AG ira ri athe sie i) f “ahr nt b buy eG pretres hy HSAIES 4 ig ae vit moar 1" ; nia, Mgt ANG ' 1 apis Ci test At ayn ts bata, vada 2 Bix 20 nae iLO Ty ecboy ts se! a a aN MS ib ents © a ee Stake bel mOjotOMy TS fill ; vba bola e wed tO fina cata RISA TTA, ; Soy e3 tgs a . ae we 4 ott, Ke '} aS =i * ne Ht ve Why Pee SAL | ean Pa Fy He sty, Bis ol he re Head 16 eta wo Ge ehh ear. nade pra a8 ae pulls ong) rh pene, ont ft Pea shea fu Chg Lote Sati } asa Ma a by ihe, Ni ”, : in we res, iy) 4 “O se: si ore 4 [st ane ete bate eT gn PL Lent hii anit tytn YO Ts Tie ; ae stil Obl Bae toniad Tihs 39 tit PLATE IX. Figs. 1 to 5. PACHYDICTYA FOLIATA Ulr 1. Tangential section, x18, cutting the zoarium a little obliquely. The figure which was inadvertently placed upside down on the stone represents a spot of the section where inequality of levei caused the zoarium to be divided in such a manner that it brings into rapid review the various changes from the base of the zocecial tubes to the surface. The shaded and vertically lineate zone in the lower part of the figure represents the median tubuli and lamine. bo tubes ina well preserved specimen. 3. Small portion of same x35, to show the minutely tubular character of the zowcial walls. Vertical section, 18. 5. About two thirds of the width of a transverse section, <18,showing median tubuli very distinctly. (See also plate X.) Lower third of the Trenton shales, St. Paul and Minneapolis. Bigs 6:and 105. sPACHYDICTYAy OCCIDENDATISNU Mn ascent eeoteenctenenne chen ctieeceice nee 6. Represents a small portion of a tangential section just beneath a bifurcation of the zoarium, X18. At this point it is common to find, as in the present case, that the longitudinal interspaces are wider and with more lines of median tubuli than usual. 10. Vertical section x18. (See also plate VIII). Upper third of the Trenton shales at St. Paul. igi. 7: (PACH Y DICT YAVA CUA (EV AVI) cic patssecs tis vets acess ote rare oto eveunrors cevoVarane ioiateteyens axelavers ovations Vaterewsieletelaterstetesiets Tangential section of a specimen from Cannon Falls, Minn. (See also plate VIII). Higs. 8iand’9! SPACHY DICTA WL EGIANS)) Ws eS] everesoyc le tesiereiisyatelaie oieie ie eis ove reiacale eteletetsleuersiereteltinie siehetelsieterensievere 8. Tangential section, X18, cut obliquely so as toshow parts of both sides of the zoarium. This specimen was very old and thick and in the outer part (upper third of figure) de- veloped two extra lines of median tubuli in each longitudinal interspace. The end spaces are also unusually long. 9. Small portion of same section, X35. (See also plate VIII). Base of Galena shales, St. Paul, Minn. > Higgs Iivand eZ RIGONODICTY-AxCON CIELATR Ix Wl Peace re etltepeioneileleeeidieisiaieiciecicrselseisiareiieieisstesetictet= 11. Transverse section, X18. 12. Tangential section, X18, from a specimen in an unusually good state of preservation. (See also plate X), Upper third of the Trenton shales near Cannon Falls, Minn. HGS sand 4s PACH NDI OMA UME RDA ACUI eis rateyetaraistetelsterste = otalaletelatetelalatepselejeleiedsyslel=iatedelalefalststeiiaratelelsye 13. Tangential section, x18. At the upper end of the figure the section sinks to the level of the median lamine. 14. Small portion of one of the longitudinal interspaces and adjoining walls of several zoce- cia, X35. (See also plate VIII). Middle third of the Trenton shales, St. Paul and Minneapolis. Tangential section X18, showing structure in the outer half of one of the layers of zoccial 151 155 154 160 152 BRD LOCO H arp MEW PORN fh LORD SURV ReOreiiINNES O1Aae ( Bryozoa.] Vol. HIT. PL IX. ‘The Henderson -Achert Lith.Co, Cin.0 E.0.U.«C.S del ot Lith Tee Cesar ug ; fate Woes i BARS ey ‘ LA A . pea eee es, | oe elegant Bape HA eo ree Syiaey #3 e a Oat 4 hiyieuirs GF Z | Beet (eee a Ui 4 fal . ral as : nal 2 pe asg ut : 2 ; 1 oR ayer r Taye Ne Bows mas ON! fae ; + Dice eRR WO WEL 572. ae bis y : " *! ; Big ; 0 > oid ‘ rae ae ALLO. LLY ay ue Hie re.) PLATE X INE OE TUN Glan aoyCoprdN yaeplnae > 1ONles Groosoe somo oncodosqooonnanoonBoeDDS000 t Jonsadaosenaadudoone 157 1. A group of specimens of the natural size. 2and 3. Two fragments, natural size and <9, with some of the zocecial apertures closed. 4, The basal part of a rather young example, natural size and x9. (See also plate VIII). Upper part of the Galena shales, near Cannon Falls, Minn. Migs pybOel OPA CHD ICT VAG HOT DATHAM UIC anette tartaric ehieieavictereticiicierleracisinietarsvoiaisteielawieraiierer te 149 5 to8. Four specimens of the natural size. Fig. 6 presents the unusual condition of raised macula. 9. Surface of fully matured example, x9. 10. Surface of a young zoarium, X18. (See also plate IX). HIgs ll tod) PACH Y DICT YA MD RISH TAT IS iW) livarpertereterterctetste nett reicislspaistetetarsictete eke nlere cketetelctsieheystaleetstetatas 159 11. Portion of a block of limestone with a group of the slender ramulets of this species, natural size. 12. Surface of an old example, x18, on which many of the zocecial apertures preserve the closures. 13 and 14. Two transverse sections, *25, the first prepared from a young example, the sec- ond from one like the original of fig. 12. Trenton limestone, Montreal, Can. Higsidovbo;20;) ZL RTEONODIOT YA. CONCIGTAMRTexaeiUilitypiaye lature tecarsy ctareleeteintareiercterevaleveleceisieterete eicteretatstatetateretsteeke 160 15 to 19. Fivespecimens of the natural size, illustrating the zoarial variability of the species. , 20. Surface of well preserved example x9. (See also plate IX.) Upper third of the Trenton shales near Cannon Falls, Minn. Rigs :21b0).25) STICLOPORELE A; CRIBROSAUW lt. seereaeer cies cere cits einer er ree tterets 184 21. Nearly complete zoarium of the prevailing type of this species, natural size. 22. A thin fragment less regularly developed than usual. 23. Surface of an excellently preserved example, x9. 24. Another portion of same X18. In this specimen the mesopores are very oumerous. 25. Tangential section of an average specimen, X18. In the upper part of the figure the section descends to the level of the prostrate portion of the zocecial tubes. (See also plate XI.) Middle third of the Trenton shales at Minneapolis. DRESS URVEX@Or MINES DAG The Henderson -Achert Lith.Co. Cin.O | Bryozoa.} Ath I P TD 1A W] ve Ne TC ans PEO MIG EOU.«C,S.del et Lith te ent ' ah re ae aaltalves p : he id aa wile uty Ret il ont MT puns! Vette ABV ED Oa bs dg iy 6, eslgM MMM AT O01) pistols aw (ae writ ioe ws tibiht ou iy ict ‘wet a di low rs Fe is gosta Bey iting ams! tae sith put twine: > soba v bate muls otis a isp Yo. mon 5 ae rp , st ite un orp eth aa e i ‘a sii i work bist oo ioe jor Y nbtae a) iy led byeVAM ey) OST Migs 1 to\3, 6, and 8)todl-, (ISTIGCTOPORETE A ANGUIEARIS UII soe: cteleletnlele aleirielete/olatel=\-1mtatalel=ln eleleia!elen =reieleisie 182 1 to 3. Three specimens of the usual form of this species, natural size. 6. Surface of an average example, <9. 8,10 and 11. Tangential, transverse, and vertical sections, X18, prepared from the oldest example at hand. 9. Small portion of a tangential section X50, showing the minutely tubular character of the divisional line between adjoining zccecial walls. Lower third of the Trenton shales at St. Paul and Minneapolis. Figs. 4,5 and 7. STICTOPORELLA ANGULARIS, Var. INTERMEDIA, D. Val.........seesceeeee ee cece cece 183 4. A small subfrondescent example from the base of the shales at Minneapolis. 5. A fragment of the usual form of the variety from tne same horizon in Fillmore county. 7. Surface of same X18, showing the extreme paucity of mesopores and in the upper left corner a portion of one of the clusters of thin-walled zocecia. Migs 12 L019) Ss STICTOPOR EGET AVM OND TOE ER ACUI © pani iat 1 sedi aa) a lox iD 'tsiad es think Cte A. = 7 ie ag Se eam yim mmodo coi (iin eS 40 ee ore ey 5) eer ; Tee bei Terrie auth Poe Beir nimi. ae ene Peat eet to'4 Se ES. Seayibas pcre Thar Hat anes ce JRdit aree i aH HEE panne ts Wy abana Hides ot a Meera. Apres PF Gaby thy tens ee satan Aree ips fh Y puis yadiy xh es Ja! shen “Dynadeyo paty a cee ‘ ar; PLATE XII. PAGE. Higs: 1-0 4,30\and 31. HSCHAROPORA ANGULARIS, 1. SDise cc occ’ «jee vic) leie/alele «\e1s\eis «/e\e1si=\nai*) + \0\n\0\~\= 168 land 2. A small specimen of natural size and the greater portion of it <9. 3and4. A large specimen of the natural size and a portion of the upper half of its sur- face X18. 30 and 31. Vertical and tangential sections, x18. Trenton limestone, Minneapolis. MIPS D012 04 SCHAAR OPORANSUBR RE CIA MU lirtirpstatarerstcteretetatslers)sjcleleloteteteslelstetonvayelsteneleferareteepstetetstetTetetata(elelstels 168 5 to 17. A series of specimens, most of them above the average in size and the four last with from one to three rows of monticules. 18 and 19. The central and basal portions of the original of fig. 9, <9. 20. Part of same, X18. The characters as shown in this specimen are to be regarded as typical for the species in its younger stages. 21. Surface of another small example, X18, with the marginal rows of zocecia unusually conspicuous. 22. Surface of the basal third of the original of fig. 15, 18. The features here presented are unusual. 23. Surface of the upper part of the original of fig. 16, x18. 24. Surface of the original of fig. 17, x18. In the specimen the zocecial apertures manifest a tendency to arrange themselves in an obscurely pinnate manner. 25. Tangential section of an example corresponding to fig. 9; *18. 26. Tangential section of a specimen of the size of fig. 8, or a trifle larger; x18. 27. Tangential section, X18, showing the appearance just beneath the surface of an old example. ; 28. Vertical section of several zocecia prepared from an average specimen, *18. 29. Transverse section of same X12. Middle third of the Trenton shales at St. Paul and Minneapolis. CEOMOCTOM NT VALU RAUPHIS TORRES URGE REO FSMINNES OLAS ( Bryozoa Vol. ITT. PIXT. WL) \} LF ty) y) 4! bes eye SE ia Ooi) ae igus dary Tien. Yer ,8 Py pyhiteed — ; ] 4th) dial eee ‘ oe itt LTO. PLATE XIII. Figs. 1 to 11. ESCHAROPORA CONFLUENS, 0D SDP.......-...0--ee eee oe aalelelersistemnisseieta s,sreminrsias mado dONb se 171 1. A specimen that preserves the pointed articulating base; natural size. 2. Well preserved fragment, the surface of which is enlarged in fig. 5. 3. Portion of a large specimen with comparatively remote bifurcations and obscure monti- cules; natural size. 4. Incomplete basal part of another large zoarium; natural size. 5. Surface of the original of fig. 2, x9. The line above indicates the contour of the surface in a transverse section. 6. Tangential section, X18, of a well preserved example. The figure embraces about two- thirds of the width of the branch. the right side being marginal. 7. Several zooecia of the same section, X35, showing the mural lineation. . Another portion of the same section, 18, showing the prostrate part of the zoccia. 9. Left half of another section, 18, prepared from a specimen in a less favorable (the usual) state of preservation. In this example the marginal zocecia were uncommonly large 10 and 11. Transverse and vertical sections X18. Middle third of the Trenton shales at Minneapolis. ge Figs. 12 and 13. EscHAROPORA (?) LIMITARIS, 0 Sp. Or Var......-- eialoraleser atarerntetel sterereversy sister einer Seacoos ~) llr 12. A very large specimen, provisionally referred to this species; natural size. Middle third of the Trenton shales at Minneapolis. Survey Museum. Reg. No. 5930. 13. A specimen of the average size of the species as it occurs in the lower third of the shales at Minneapolis. (For internal structure see figure 9 on page 172.) Figs. 14 to17. PH4&NOPORA INCIPIENS, D. Sp..... Snodadounuoopadoonn Doon aatoagod sonsbnepdocnasscna 2 ult! 14. A fragment of the natural size and a partof it X18. Trenton limcetone: Montreal, Can. 15. The basal part of a zoarium from the Trenton limestone at Chimney Point, Vermont. 16. Tangential section, *18, of a specimen from Montreal. 17. Tangential section of another specimen from Montreal, X28, showing structure imme- diately beneath the surface. Figs. 18 to 21. ST1cTOPORELLA EXIGUA, 0. Sp.* 18. Portion of the delicale zoarium of this species, natural size. 19. Surface of oneof the branches *18. 20. Tangential section X28. 21. Transverse section *18. Trenton limestone, Montreal, Can. Figs. 22 to 26. PH@NOPORA WILMINGTONENSIS, 0 SP..........--+ BAO Ods SAOOn OO sce Ho nonapnaeatos a 947i) 22. Fragmentary example of the natural size. 3 23. Surface of same <9. 24. Two portions of a tangential section, <18, the upper showing the appearance just beneath the surface, the lower just over the prostrate part of the zocecial tubes. 25. One of the zocecia and portions of the adjoining ones X35 to show the minute structure of the walls. 26. Vertical section, x18. *The description of this interesting species having unfortunately been omitted from its proper place in the text, the following brief diagnosis of its peculiarities is added here: Zoarium consisting of slender and frequently dividing branches, not exceeding 1.5 mm. in width; margins parallel, scarcely sharp. Zocecial apertures oval, more or less oblique, arranged in eight or nine longitudinal rows, six or seven in3 mm,, between longitudinal ridges; diagonally three or four inl mm. End interspaces two or three times as long as the width of the space between the ridges, rsiing distally, usually with two elongate shallow pits or furrows. All that is known of the interior is shown in the figures. The types were collected at Montreal, Oanada, in the Trenton limestone, by Mr. T. CO. Curry, for the Peter Redpath Museum, from which institution they were obtained by the author in exchange for other fossils, DPE, Li N \ — YB Ue ave tey ABTS ‘ GA i Lit weet, HERE, 5 if Plate XI. VOL.UI a HS sesseetees Petes: hth. U del et pie wligzmydive + 4 < . “ - Wa aS ees aN ) or ; h peaigqerdiqerh sa mero 4b 9 ic telnnes Hubli gai as de gaye wit ® ty Sa Ree 2 RD * IG : P.. a. Anotirat AE SS, J 23aitp byias sho eile ec ber Soe ra, Vir Seen ay: shy Aqarw re z aye y ee Serr PLATE XIV. Figs. 1 to 8. PHYLLODICTYA VARIA, D.SDP..-. sees cece ee nec e cere tenn e tees eee teen eee e ee eeeceencees 1. A fragment with subparallel margins, natural size. Surface of same 9. Two rows of apertures *18; shows the papillose character of the ridges. Vertical section, 18. By an oversight the diaphragms are wanting in this figure. Each tube should have one crossing it at right angles at a point about midway between its aperture and the mesial line. — 5. Tangential section X18. The internal characters are but illy preserved in even the best of the specimens sectioned. 6and7. Old zoarium of the natural size with a portion of its surface x9. With age the maculz become more distinct and the longitudinal arrangement of the zocecial aper- tures less obvious. : 8. Portion of a zoarium larger and wider than usual; natural size. Middle third of the Trenton shales at Minneapolis. Figs. 9 to11. EURYDICTYA MULTIPORA (?PHall, SP.)........-22 ssc ceee ee cose cere ee eee t eee seen teenies 9. Fragment of a slightly undulating expansion, natural size. 10. Surface of same, <9. 11. Small portion of same, X18. : Upper third of the Trenton shales, St. Paul. Survey Museum, Reg. No. 5942. Figs. 12 to 21. ARTHROPORA SIMPLEX UIPr.......... cee ec ee eee cet e cee cree cece reece ce tence tence 12. Two segments of the usual size. 13 and 14. Two bifiurcating segments, probably abnormal; natural size. 15. Several segments preservel in their natural positions, natural size. 16. Surface of a well preserved fragment, X18. . 17. Several zocecial apertures of same, X35. In many specimens the longitudinal prolon- gations from the ends of the inner ring of papille are longer, in some cases even joining. 18. Irregularly divided basal joint, natural size. 19. The lower part of same, <9. It is difficult to make out the apertures, the whole sur- face appearing to be covered with closely intertwining striz. 20. Vertical section, *18. showing the form of the zocecia, the hemisepta, and other fea- tures. : 21. Three portions of a tangential section, x35. In a the right hand third shows the struc- ture just beneath the surface. Inthe middle third the section sinks to the level of the prostrate part of the zocecia and in some of them both kinds of hemisepta are shown. On the left side the dark band represents the noncelluliferous margin. In c we haye only the prostrate part of the zocecia and the dense margin. Middle third of the Trenton shales at Minneapolis. Figs. 22 to 25. ARTHROPORA BIFURCATA, -I. SP..e.e.eee cece eee e eee e tee e eset eee eee er nte cn see aces 22. A small segment natural size and its upper part *18. 23 and 24. Two old segments, the last one probably the basal, of the natural size. 25. Surface of the original of fig. 23, x18, illustrating the aged condition in contrast with the youthful stage represented in fig. 22. Upper third of the Trenton shales, St. Paul. Fig. 26. ARTHROPORA REVERSA, UO. SD..esseeecec se see eens cere ete eetecee ce ceee ences eteesecenees : Natural size view of an average segment, and a portion of its surface x35. Base of the Galena shales at St. Paul. Pet 139 177 178 178 BAU Aa WYEee, TER SLC Ue et AP COT A UL EN, ( : | Bryozoa| VOL. 1 Plate XIV. =a oe om SS THE HENDERSON “ACHERT-KREBS Lith. Co Gancinnan ar Min tp able be aaa SU 7 * ay ¥ Faw Lets OW, ni! “qilog peta eer a ‘Ba : HEA Poss iad incieuni wel rege it Hwee (a ae) ere hrdeteny Bt *- -—% Ps VR ys i) a is Lee PLATE XV. Figs. 1 to 6. MONTICULIPORA (?PRASOPORA) GRANDIS UIP... .....-2- 02s eeeeee eee e eee ene cee se ee ceee 219 1. A small lobate mass of the natural size. Fragment of a subramose example, natural size. Surface of same *9. Several zocecia of same, X18, exposing the cystiphragms. Tangential section <18. Three portions of a vertical section, X18, showing extremes of variation in the tabula- tion of the zocecial tubes. Mus. Reg. No. 5969. Base of the Trenton shales at Minneapolis. Figs. 7and 8. MONTICULIPORA WETHERBYI PUITICH...........0 2c eee ete eee eee tone ete tens ence 218 Tangential and transverse sections, X18, of a specimen from the Trenton limestone at Minneapolis. Mus. Reg. No. 5967. Figs. 9 to 12, MONTICULIPORA INCOMPTA, Te SP occ ce cce. eee wnc ences = velne semen ocean snccsers=oree 219 9. Tangential section X18. 10. Small portion of same 50, showing the peculiar structure of the walls. 11. Vertical section <18. 12. One of the walls X50. Middle third of the Trenton shales, Minneapolis. Mus. Reg. No. 5968. Figs: 13) todd. “ATACTOPORELUATINSUEDA =D. SPs sc aeicl/c ele elotale fe o1c'n cl= stole Cleis efetals tw avelvle]oielsis[aielaitelelele sie/=!uisie 224 13. A crinoid column covered with the zoarium of this species, natural size. 14. Tangential section X18. 15. Portion of same x50. (See also plate XVIII.) Middle third of the Trenton shales at Minneapolis. Mus. Reg. No. 5985. Figs. 16 and 17. ATACTOPORELLA TYPICALIS, Var. PRACIPTA, D. VAP... 2. seus ccseneme recess ernssene 223 16. Vertical section <18. 17. Tangential section *50. (See also plate XVIII.) Middle third of the Trenton shales, Minneapolis. Mus. Reg. No. 5984. Figs. 18 to 21. ATACTOPORELLA CRASSA, DT. SP... esc eece en cece cece ences ee tecees cae cere cece ccece 225 18. Tangential section <18. 19. Small portion of same, x50, showing the structure immediately beneath the surface of a matured example. 20. Another portion of same 50, showing the appearance at a deeper level in the zoarium. 21. Vertical section, 18. Galera shales near Cannon Falls, Minn. Ga RAUS BS ES ESUa AY f \ as wl Pe UES i > SLU. he Si i) aXe Baths © ate XV. Pi RSONACHERT -KREBS LITH. Co. CiINcINNAT. THe HENDE 2 ae A_Jy- VOL E.0.U. del.et hth. . ening in ey EN > Qa prana Se Rit zie \ a 4 Pakeameens 7‘ ¥ ; as vt re Te et ry =| fie Eo le ee pal bv ty te x “s a, ee ‘. 4 es Ry ieee ¢ - x WRI SAS polwin Z ey ate ty hs t ak oe et ae nee : te teits Kop €: it Raia: 9 1). Si) Meld 4 oY” OLDE His 4 % PLATE XVI Kies: 1t010-: VERASOPORALSUM Ul ACU Tex UDI e5s )olinlo sls io.o over aiarels)s\o/alejcreie ots talalstolaleeteisvaists oleritareret aisieteistersieiee land6. Vertical and tangential sections, X18, of a specimen of the var. orientalis from Trenton Falls, N. Y. 2and7. Similar sections of a Canadian (Ottawa) example of the same variety. 3and8. Similar sections of a Kentucky specimen of the western or typical form of the species. 4and9. Vertical and tangential sections of a specimen from the lower part of the Galena limestone at Mantorville. Minn. Mus. Reg. No. 5986. 5 and 10. Similar sections of another example of the typical form of the species from the upper third of the Trenton shales at St. Paul. Bigs pllsbOnlbs eR ASO POH Al CON OLDIE AGU crtter ete reretetaeteyofeastatsleteleretstavenareleinystereretst= aveleilep=ialaletoietaie stele stae tel tater 11 to 13. Lateral, basal, and one sectional view of three specimens of this species, natural size. 14. Tangential section <18, showing the thin walls and minute acanthopores which are characteristic of the species. 15. Vertical section, X18. The abundant tabulation of the tubes is the chief peculiarity brought out by this kind of section. Upper third of the Trenton shales near Cannon Falls, Minn. Wigs Gand ieee PRASOLORAVSEL WAYNE @ NICH OLS Ol tiereiaxelalcttalells ce oie oreo aie eicieisioieieians(-feinietstetere ist eteieicie tetera 16. Vertical section X18, showing the isolation and semi-circular form of the cystiphragms. 17. Transverse section of same X18. Upper part of the Galena shales near Cannon Falls, Minn. Figs. 18 and 19, PRASOPORA INSULARIS, Var. FILLMORENSITS, 1. Val......--cc+cececsceeccee ceseee 18. A tangential section X18, showing the different appearance of the ateenoeaat spaces when compared with typical P. insularis. 19. Small portion of a vertical section 18, showing the vesicular character of the inter- spaces to which is due the difference referred to in the preceding paragraph. Probably from the Trenton shales near Fountain, Minn: Higsy 20to 2a CE RASOPORAGIN SUM ARIS, pM eg SP iraiarercrareteleyateiataterteyotetenetsteleta ofeie tale feheyete efenmnrerellcpeistaul-ie\eleletefetetstelste 20. Tangential section of an excellently preserved specimen, X18. 21. Small portion of same 50 to show the minutely cellulose character of the walls. 22. One zocecial tube with adjacent mesopores and one wall with adjoining cystiphragms and diaphragms, 18. In showing the much greater abundance of the cystiphragms and diaphragms when compared with other species of the genus, this figure, though small, is sufficient for the identification of the present species. 23. Small portion of another tangential section, x18, in which the zoccial tubes are more frequently in contact than in fig. 20. Galena shales near Cannon Falls, Minn. Bigs. 24 to:26-— PRASOPORAS CONIDEG UA Wilyayercretetate eievepeislori=lajelaleicleisy in1s/=elaleiel=tall[nicteta[= 5 24 and 25. Vertical and tangential sections, 18, of a specimen from the upper part of the Trenton shales of Goodhue county, Minn. 26. One zocecium and adjoining mesopores of same x35, Mus. Reg. No. 5989. 249 250 252 251 249 SR =) ayaa) — “CDF PCOS 5 UL EEN, Bw Ul ho ND RY LESS Plate XVI. VOL.I1 THE HENDERSON -ACHERT-KREBS Livy. Co Cincnmant E.0.U.del.et fith. a ghar. \ , 4 a . : Do sere yas eee jae) there 710 alligie: 4 . fe Tuba neds el) RCE iesite i Fo of Sa In ir G PLATE XVII. IGS IEhOISs so MIRSOMR VPA TNBTD AL, WME are aretstaresa)ssaye osteo vele als) lors roierevs co ofelstesedayorafololotelaveieverateleeie) sinielsereleisie(ere 258 land 2. Two tangential sections prepared from the same example, X18. The first illus- trates the fully matured condition, the second an earlier level in the zoarium. 'Tren- ton shales near Fountain, Minn. 3to5. Three portions of a large vertical section of the same, <18, showing the variable disposition and appearance of zocecial diaphragms. 6. Portion of another vertical section of same X18. Mus. Reg. No. 5993. 7. Surface of same, <9, showing a condition approximately intermediate between figs. 1 and 2. 8. Surface of a parasitic specimen in a condition corresponding with fig. 1. Middle third of the Trenton shales, Minneapolis. Migs 9GO 2) SM ESOMR Yar AN ((P)ISPENOSIAG TENS Js cre ohclolefesevateteratnletaiayeleletela/stefatsl slekeha(scolelatepitaVexersiayol=el-yeleislntaistedetelsts 259 9. Surface of well preserved example, showing the round form and regular arrangement of the zocecial apertures, and the strong acanthopores; 9. 10 and 11. Tangential section, *18, and parts of several zocecia *50. 12. Small portion of a vertical section, X18, Showing unmistakable cystiphragms in the lower half. Other parts of the same section are like figs. 3 and 4 of this plate. Middle third of the Trenton shales at St. Paul and Minneapolis. Figs. 13 to 21. ASPIDOPORA ELEGANTULA, D.SP.--eseec cee ce cece ccc cece ee eee cnet eset tees eens tens 256 13. A fine example of this species on the surface of which an intermittent second layer of zocecia was forming; natural size. 14. One of the areas of the secondary layer, <9. = 15. Tangential section prepared from the primary layer of same, *18. 16 and 17. Views of the upper and lower sides of a specimen that consists of at least four distinct layers grown loosely over each other; natural size. 18. Upper surface of same, *9. 19. Tangential section of one of the layers of same, <18. 20. Parts of several zocecia of a tangential section, <50. 21. Several zocecia and mesopores as seen in a vertical section of one of the layers, X18. Galena shales, Kenyon, Minn. These two specimens were collected by W. H. Scofield and kindly presented by him to the author. Figs. 22 to 25. PRASOPORA LENTICULARIS, 0. SP...-.-s seen cecee cee cece eee eee e ete e eee cee eee secu ence 253 22. Upper surface and sectional view of an example of this species; natural size. 23. Two portions of a tangential section of same, X18, the upper half representing the ap- pearance in the upper third, the lower half that in the basal third of the zoarium. 24. One of the zocecia and adjoining parts of same, 50. 25. Vertical section of same, X18, showing the comparatively loose tabulation of the two sets of tubes. Upper third of the Trenton shales at St. Paul. Figs. 26 to 32. ASPIDOPORA PARASITICA UIT... .... 06 .e cece cee e eee eect tere ee eee ene e eee eee en eens 25% 26 add 27. Portions of a tangential section, x18 and <50, with few cystiphragms and zocecia very slightly larger than usual, 28. Vertical section of same specimen, X18, showing entire thickness. 29. Surface of same, x9. 30 to 32. Tangential and vertical sections, <18, and the surface 9, of a thicker zoarium. Lower third of the Trenton shales, Minneapolis and near Fountain, Minn. XVIL Plate eth SUR ee ) £ x. Tey bh Y Lia fae Ue oS a ) Bryozoa! BS — Ly THES Fra AoE Le VOL I RT-KRE THE HENDERSON “ACHE a ‘ Seed: <205 206 scant ses Sheree. mW Let \ TOT st: a 233 van 2 ee To) WN “ INTITTT FASB O: Fora ani seertrere rt Yat HDT Tz, hhh ) \" 0 a aay ae ass 4 J i] , j 5 = LLL titi ene e aa | « LASS. Seaanitiaciatmtemaiittt +\ \\ NA \ TORRE bebidas Lobe Lepi eR 1 wv 2 a, u oe amas MeL Le wo i eka ; PETSUDIOT Betis ix ‘ - =f ’ eck < 52 WS TORy ee. «pe Bix : => als ' eh Y Deo ae pbraog bad G oat a - =, pen PLATE XVIII. Figs. 1to4. ATACTOPORELLA TYPICALIS, Var. PRAICIPTA, D. VAL. .... sec e eee eee e reece er eeee Sinelclare 223 land 2. Tangential and vertical sections of a thick expansion, x18. 3. Surface of well preserved specimen, 18. 4. A montiferous variety attached to the shell of Orthis subequata Conrad. (See also plate XV.) Middle third of the Trenton shales, St. Paul. HMigey oibO1Ss 1A TACTOPROR ELT AVINS UE DAUM s(SD) sicleistslfaievelelous olelsiclatels'etoteretotelateieleletaielateteters)a)etsleseteieteicievalal=fel=iniele 224 5and6. Vertical and tangential sections of an example that is typical for the species in all respects excepting that the acanthopores are less numerous than usual: X18. (See also plate XV.) ' 7and 8. Tangential section and surface X18, of a variety with larger zocecia than the typi- cal and common form of the species. Middle third of the Trenton shales, Minneapolis. Wigs 29 tO 0 ie HLOMOTRYPH LG AsENS TAR DE IS a Wil pstatstatotelsstotetateteterelejeletaletenetere ciate lelelateiitereletetays eferecsfs\eyalsi=telat =talets 22 9to1l. Three fragments of the natural size, showing extremes in the size of the branches. 12. Surface of well preserved example X18, with the mesopores open and distinctly visible and the walls thin. 13.and15. Tangential and vertical sections X18, prepared from the original of fig. 9. The walls are thick in the peripheral region and very few cystiphragms are noticeable in the tangential section. 14. Small portion of same tangential section <50 to show the minute structure more clearly. 16. Central part of a transverse section of same specimen, *18. 17 and 18. Vertical and tangential sections X18, of a specimen with two series of cystiph— ragms, thinner walls, much larger maculx, and more abundant acanthopores than the preceding. 19. Portion of one of the clusters of mesopores 50. 20. Several zocecia of thesame tangential section 50. Middle third of the Trenton shales, St. Paul and Minneapolis. Migsa2lkands225 | HOMORRY PEEL AGM Oil LEE O RAW AY SIN-ES [0 islesesedi sta lat= fore lerntele talatelolistarstetel chelated ste aareteratalsvelets(scefer= 280 21. Tangential section X18, showing, among other peculiarities of the species, the abun- dance of the mesopores. 22. Peripheral part of a vertical section X18, showing the comparatively remote tabulation of the tubes. Middle third of the Trenton shales, St. Paul. Hi GSh123 60) GOs HOMOTR WP HLTA (7) OVEAD AIST s)yerejepetetaerelateteretateyauereicTelatensfaleterstsleletarelelsieietsyetslatelaistele/atal=IsieTe 231 23 to 26. The basal part of a zoarium and three representative branches of the natural size. 27. Well preserved fragment of the natural size and a portion of its surface 18. 28 and 29. Verticaland tangential sections X18. 30. One zocecium and adjacent parts of the tangential section, x50. Galena shales near Cannon Falls, Minn. Migs al Loss: LHOMOTRY PEL TA RUSTIO A, | T1s) SD s\eja(slelate/=tal=(orareletsietalsatevelelsleimeteltsialcle rs sialaiateloleteloisisfele Apodnoe 234 31. Vertical section <18. 32. Two portions of a tangential section X18, the upper part giving the appearance imme- diately beneath the surface while the lower represents a deeper level. 33. Small portion of the mature region of the tangential section x50. Upper part of the Hudson River group near Spring Valley, Minn. BAU oa WY, VERE, SLAY ANC Dig 0 BGS ES UR BEN, ) Bryozoa | VOL.IH Plate XVIII E.0.U. del et Hth THt HENDERSON -AcHERT-KReBs Liv. Co. Cincinsun Je giz ak Ts ra ste Wt arp 1 SS seit Nisha iresrt visti By a TT RS Ey. ; wabeds naroar.-a a PLATE XIX. Figs. 1 to 9. HOMOTRYPA MINNESOTENSIS UlP.... 2.00.0 see e eee e ence cen e eee eee teeecscceccnces 235 1to3. Vertical, transverse and tangential sections X18, of a specimen having the walls in the peripheral region thicker than usual. Mus. Reg. No, 5970. 3a. Small portion of a tangential section of an example of the var. montifera, x50. Base of the upper third of the Trenton shales at St. Paul. 4and5. Tangential and vertical sections of an average specimen, X18. 6. The peripheral part of two zocecial tubes, X18, more closely tabulated than usual. Mus. Reg. No. 5970b. 7 and 8. Two examples of the natural size. The end view under the latter shows the ex- ceeding narrowness of the peripheral region. 9. Surface of the original of fig. 7, <9. Lower third of the Trenton shales, Minneapolis. SOLOW Cou O MO TR WAU EEXSLTTS eI Te oyeteonereteretetelel etek slat slates eferelatieletsletelessteleleteteteteyalen-taterela isle! teteteralelstelstotsier=1< 236 10 and 11. Two fragments of the natural size. 12. Vertical section 18. 13. Tangential section in a pre-mature condition, x18. 14. Tangential section showing fully matured characters, 18. 15. Portion of fig. 14 more highly magnified. 16. Portion of fig. 13 more highly magnified. Lower third of the Trenton shales at Minneapolis. Figs. 17 to 20. HOMOTRYPA SEPARATA, D SP....-ccecccceccee cre coven tnccce tees sees ce ncenereeeees 237 17 and 18. Tangential section of this peculiar species, X18,and a portion of same X50. 19. Surface of a well marked specimen *9. 20. Vertical section X18. Attention is to be directed to the tabulated interstitial spaces. Lower third of the Trenton shales, Minneapolis. Figs. 21 to 28. HOMOTRYPA SUBRAMOSA UIP. 2.0.0... cece. ccc cece cece teen cr secsrncscereccicressseess 229 21. View of a characteristic specimen showing the irregular division of the branches. 22,24 and 25. A series of three tangential sections <18, agreeing in all respects except that while in the first the acanthopores are numerous and well developed they are fewer in the second and quite inconspicuous in the third. Original of fig. 24 belongs to Survey Museum, Reg. No. 5980a. 23. Small portion of fig. 22 more highly magnified. 26. Vertical section x18, of a specimen having the outermost region loosely tabulated; very unusual. Mus. Reg. No. 5980b. 27. Vertical section of a typical example, <18. 28. Surface of an average example, showing the cystiphragms in the zocecial apertures, <9. Upper third of the Trenton shales, St. Paul and near Cannon Falls. E.0.U. del.et lth. & rege Oo 0% cr Cry ae THE HENDERSON “ACHERT-KReBs Litt. Co Cincinn nL ie PLATE XxX. Figs. 1 to 9, 138 and 14. MONTICULIPORA ARBORBA, D. SP....eeee ses e cece ee eee cette tee eee ence ee ean es 220 1. Peripheral part of a vertical section *18. 2. Several tubes from the axial region of same X18, showing the presence of cystiphragms in even this portion of the zoarium. ; 3. Transverse section from the center to the periphery of a branch <18, proving the presence of cystiphragms throughout. 4and 5. Fully matured portion of a tangential section X18 and a small part of same X50. 6. Shows the appearance at a slightly lower level than fig. 4. 7. Small portion of the surface of the specimen represented by flg. 8; <9. 8 and 9. Two fragments of the natural size exhibiting a difference in the prominence of the monticules. Galena shales near Cannon Falls, Minn. 13 and 14. Tangential and vertical sections of a form of thespecies from the Trenton at Burgin, Ky.; *18. Figs. 10 to 12. MONTICULIPORA (?) CANNONENSIS, I. SP..-.- 2. eee eee ee cette eee eer eee eee e ne eeee ees 221 10 and 11. Vertical and tangential sections x18. 12, One zocecium 50. Galena shales near Cannon Falls, Minn. Figs. 15 to 21, HOoMOTRYPA CALLOSA, 1. SP... ..- sees sees ce eee eee eee ee cee cece eet e ee cece e ee eeee 243 15 and 16. Tangential section*18 and a small portion of same 450, of a specimen from the Galena shales near Cannon Falls. 17. Vertical section of same 18. 18 and 19. Peripheral and axial portions of a vertical section 18, prepared from a specimen from the Trenton at Burgin, Ky. 20 and 21. Tangential section of same X18 and X50, differing slightly from that of the Min- nesota form. Figs. 22 to 27. ATACTOPORELLA RAMOSA, D.SP....- ssc ceee ee eee scence te eee rete e eee cence ee cees 226 22. Two portions of a tangential section 18, exhibiting differences that depend upon the varying depth at which the section passes through the zoarium. 23. Small portion of same more highly magnified. 24. Axial region of a transverse section 18. 25. Vertical section X18, showing the continuance of the series of cystiphragms into the axial region. 26 and 27. Two specimens of the natural size. Upper third of the Trenton shales near Cannon Falls, Minn. Figs 28 to 33. HOMOTRYPA SIMILIS Foord*.........- 20s eee e rece cee ee cence eee e nets eee een eeeee ees 242 28. Portion of the peripheral third of a transverse section x18, Cannon Falls. 29, Vertical section of an authentic Canadian example of the species x18. 30. Two portions of a tangential section of same *18. 31 and 32. Vertical and tangential sections of a Minnesota specimen, *18. 33. Surface of another specimen from this state <18. Trenton limestone Ottawa, Can., and upper part of the Galena shales near Cannon Falls, Minn. *The systematic position of this species is doubtful. Though falling in a loose way under Homotrypa some of its char- acters are so peculiar that it can in no wise be regarded as a true representative of the genus. ‘Thin sections are suggest- i vely like those of Homotrypella instabilis and in some features also simulate those of Eridotrypa mutabilis. VOL. II Plate 20. E.0.U.del.et Lith. Macerair Lith. Co, Cin.0. ei g SL SS NiKias & pn a ys eo BE | Tay HOtTDR 15 ees PLATE XXI. Figs. 1 to 7. CONSTELLARIA VARIA, 1. SP.... cece eee e cece eee e eee cence es tee tne cere cent tere ceseneree 311 1. Surface of a mature example, ¥9, with wide interspaces and correspondingly narrow zocecial apertures. 7 2. Surface, 18, of another example showing a less matured stage than fig. 1, the inter- spaces being thinner and the zowcial apertures larger. 3. Tangential section, X18, showing appearances immediately beneath the surface’of an old _ specimen. At deeper levels the walis are thinner and the interspaces narrower. 4. Small portion of preceding, 50, with two of the minute mural tubuli. 5. Vertical section of an average specimen, X18. 6and7. Two fragments of the natural size, one very small, the other of medium dimen- sions. Galena shales near Cannon Falls, Minn. IMS eh WO) IPL INP rohe Cop ectopic N Tope ONGWNE GI yas nocaacqonndoncudpacdop aGd0 ocdaDcbOUScaEaoD AaodDs 314 8. An unusually wide fragment of the natural size. 9. Surface of same, <9. ; 10. Two portions of a tangential section, X18, the upper illustrating the appearance just beneath the surface of a mature example, the lower at a deeper level. 11. Vertical section of same, 18. 12. Central portion of a transverse section, *18. ‘Pierce limestone”, Murfreesboro, Tenn. Figs. 13, 14, 20 and'22. NICHOLSONELLA PONDEROSA? Ulrich............0..-ececeecec cece cence e eres 316 13. Two portions of a tangential section, <18. In the original the details are obscure and it is probable that the interstitial dots are too numerous and small. 20. Small portion of the peripheral part of a vertical section, X18. The structure is but illy preserved in these sections, 14. Two portions of a tangential section of another specimen, <18, the upper immediately beneath the surface. = 22. From the peripheral part of a transverse section of same, X18. Lower third of the Trenton shales, Minneapolis. Figs. 15 to 19 and 21. NICHOLSONELLA LAMINATA, DL. SP...-.0---..0-- eee eee e eee ee sce c ee tesetseeee 315 15. Tangential section of specimen in an unusually good state of preservation, X18. 16 and 17. Portions of same 50. 18 and 19. Under side of a fragment, nat. size, and the upper surface <9. In this specimen the mesopores are shown much more Clearly than in others. 21. Small portion of a vertical section, 18, passing through one of the macule. Middle third of the Trenton shales, Minneapolis. Figs. 23 to 40. TREMATOPORA ? PRIMIGENIA (and varieties) UIrich............. see ee cence eee eee ee 309 23 to 27. Fragments of the typical form. 28 and 33. Original type of 7. ornata and surface of same x18. 29. A large specimen of var. spinosa ; 30, a smaller and better preserved fragment; 35, sur- face of the latter, *9; 36, small portion of same <18. 31. Surface, <9, of an average example of the typical form. No attempt has been made to draw the small acanthopores. 32. Surface of specimen with acanthopores unusually abundant and inflecting the zowcial apertures, X18. The specimen is peculiar also in having many of the mesopores open. 34. Original of fig. 26, x18, (var. ornata) with spines and occasional open pores in the inter spaces. 37. Tangential section, X18, from aspecimen whose surface is drawn in fig. 32. 38. More common appearance of typical tangential sections, X18. 39. Small part of preceding 50. 40. Vertical section of basal expansion, X18. It is attached to a crinoid column and shows how the tubes grew into the depressions between the rings and failed to attain ma- turity. Middle third of the,Trenton shales, Minneapolis, GEOLPANDBV AL SHI Sigs URE WEO EVN NES 02S) | Bryozoa | Plate XXl VOL.IT THE HENDERSON -AcHERrT “Kress LitH, Co. Cincinnan E.0.U.del.et Hth. ew ee = = > Haris ,. ‘ SAG ETT Ml * Se ee : ate b we OBL As ; eS ia ad: PLATE XXII. Figs. 1 to 12. CALLOPORA PULCHELLA, D. SP. secs eeee reer eect ence teense teense eset ereeeceens sees 1to3. Three typical specimens of the natural-size, 4, Surface of the original of fig. 3 *9. 5. One of the depressed spaces of same X18. : 6and 7. Two fragments, one unusually slender the other thicker than usual. 8. Portion of the original of fig.7 where the walls are thinner and the mesopores larger than usual, X18. Other parts of its surface more as shown in fig. 5. 9. Vertical section X18. 10 and 11. Average tangential section 18 and small portion of same 50. 12. Transverse section, natural size and one fifth of it X18. Note comparatively small size of the tubes in the axial region and wide peripheral region. Upper third of the Trenton shales, St. Paul. : Figs. 13 to 17. CALLOPORA PULCHELLA, Var. PERSIMILIS, ND. Val..... 2... e esses eee ee eee cree cece eee 13. Two fragments showing the exceeding prominence of the monticules. 14. Portion of the surface between the monticules <18. 15 and 16. Vertical and tangential sections <18. 17. A transverse section, natural size and portion of same 18. Upper third of the Trenton shales near Cannon Falls, Figs. 18 to 28. CALLOPORA CRENULATA, 1. SP... eee eee eee cece cee eee cee e eer ee nest eeeertenceetees 18. A fragment of the zoarium of this species, natural size. 19. Surface of same *9. 20. Average tangential section x18. Another, representing a more matured condition, rather closely resembles fig. 10. 21. Vertical section x18. 22. Several tubes from the axial region of same X18, showing the wavy character of the walls. Portion of one of the macule and adjacent parts of a specimen that preserves the cen- trally perforated zocecial closures, 18. Upper third of the Trenton shales, St. Paul. Figs. 24 to 31. CALLOPORA UNDULATA UlIP....... 2... cee eee cece cee e eee tee e teen cece ceee dobpns doot 24 and 25. Typical specimens of the natural size. 26. A fragment with rounded monticules. These are too prominent in the figure. 27. Nearly smooth fragment, in this respect approaching C. incontroversa. 28. Surface of the original of fig. 25, x9. 29. Tangential section 18. 30. Portion of a transverse section *18. 31. Vertical section 18. Middle third of the Trenton shales, St. Paul and Minneapolis. Figs. 33 to 836. CALLOPORA INCONTROVERSA UJY.......-..ceeese ee sees cence nec e eect ee ee cet econ ne 33. Tangential section X18, representing part of one of the clusters of large zoccia and a few of those of the ordinary size. Compared with C. undulata (fig. 29) it will be noticed that they are of more rounded shape. 34. The central part of a transverse section X18 35. The axial part of a vertical section x18. At the right upper corner one of the tubes is drawn to its aperture. 36. Anentire but rather short zocecial tube 18, showing the distribution of the diaphragms. Lower third of the trenton shales, Minneapolis. Figs. 37 to 41. CALLOPORA ANGULARIS, 0. SP. ... 0. ..- eee cece ee tee eee eet e eee ee eens eee se een eeees 37. Fragment of the natural size. 38. Vertical section X18. 39. Tangential section showing fully matured characters, <18. 40. Small portion of another tangential section *18 showing the slightly irregular character of the cells at a deeper level in the zoarium than that represented in fig. 39. 41. (14 0n some of the plates.) Axial region of a tramsverse section 18. Lower third of the Trenton shales, Minneapolis. 277 CEOLMANDSNAL SH sis URVEW ED reMINNE SO TAS) |Bryozoa { VOL. Plate XX ; p ] t f 35. A fi | ; Hf ; \f rp ett yy" err yg j | f oe eS AA i PF a) ff Pe Pf } (Soom \ i JN f \ } 4 / F 36 t Ds A ey aX pat \—= _ 4 p| sk = AY COs i. ‘A ~ Xi Conny lone = YALA Maud ke ‘Ye + t E.0.U.del et hth.. THE HENDERSON -ACHERT Kreps LiTw. Co Cwcimmum. pty" ‘Oe PLATE XXIII. BUGS ALbO}8: ACALGOPOR AsD UMATIS oN ISD mets cccterctalecist eistsieisclole ie ners sfols Samal] «mia velaehte mot ele cipisters eis taste 282 l1to4. Representative fragments of the natural size. 5. Surface of the slender piece 9. 6. Surface of another that preserves the zocecial closures, <18. Tand 8. Vertical and tangential sections <18. Upper third of the Trenton shales, St. Paul. Wigs) .95 10) 2landi29) “CATLTORORA GOODHIUENSISj 1118p ic «/-\-tejsicisieisistaeeois lols ol atelnyele eee eretotcyelsieipiaiet-ieietelalers 282 9and 10. Two fragments of the natural size. 21. Axial region of a transverse section 18. 29. Surface of a specimen 9. Galena shales near Cannon Falls, Minn. Wigs. 1) 12) 16; 17,,24-26; 30) 31. CALLOPORA MULTITABU LATA IIc. c cwle cise eicfeiei cise #0 ele nic oP eiecieiere 280 1land 12. Montiferous examples, the latter but slightly, from the Galena shales at Cannon Falls. 16. ‘Typical specimen from the upper third of the Trenton shales at St. Paul. 17. Tangential section *18, of the Galena shales form. 24. Vertical section of a specimen like fig 16, <9. 25. Surface of the original of fig. 16, <9. 26. Surface of a very finely preserved specimen x18, showing the ornamental zocecial closures. Upper third of the Trenton shales, St. Paul. 30. Surface of a specimen like the one from which the illustrated tangential section (fig 17) was prepared, x9. The figure includes one of the clusters of large zocecia. 31. Surface of a typical specimen x9. Wigs 13-15; 18-20) 2202321, ose OAL LOPOR A RAMP ANT ISD heaeee seers chienienaeielatclars icine sige rrcastetaeiees 281 13. A large irregular specimen from the Galena shales at Cannon Falls. 14and 15. Two typical examples from the base of the upper third of the Trenton shales near Fountain, Minn. 18. Tangential section X18, of another specimen from the same horizon and locality as the preceding. 19. Vertical section of the same *9. x 20. The axial region of a transverse section of the same X18. 22. and 23. Portion of one zocecial tube of a vertical section and a tangential section, <18, of a specimen like figs. 13 and 28. Galena shales, Cannon Falls. 27. Surface of the original of fig. 14, x9. 28. Surface of the original of fig. 13, x9. Figs. 32 to47. DEKAYELLA PRM NUNTIA, n. sp., and varieties. : Megs 320088.) Val. CHUNATAGuTUn valerate sisetteise icon Sa OU GA OM eANO ONO ANG to oasaEeeboens 271 32.- Typical example of this variety. : 3 33 and 34. A less compressed fragment of the natural size and a portion of its surface x9. 35 and 36. Two portions of a tangential section 18. 37. Vertical section-of the same specimen x9. ; Lower part of the upper third of the Trenton shales near Fountain, Minn. 38. Portion of a tangential section of a specimen from the upper part of the middle third of the Trenton shales at Minneapolis; x18. Other parts of this section are precisely as in fig. 36, but in the portion figured the mesopores are larger and more abundant than usual for this variety. The vertical section of this specimen is indistinguishable from fig. 37. Migs, S0ito42.\ Vari SUMP LAR. Mr cveID ccm si rtetccicte ates seat staetake ere ce RTeIs er To eet 271 39. Tangential section 18, of a specimen with thick walls. 40. Verysmall portion of the superficial region of a vertical section magnified 50 diameters to show the minute structure of the walls and the method of depositing the diaphragms. 41 and 42. Small portions of two tangential sections 50, the first with walls as in figs. 39 and 40, the second with thinner walls, parts of which are marked transversely. Lower third of the Trenton shales, Minneapolis. Fig. 43. The TyPIcaAL FORM of the SOC Bacumacodcco, cob nono aenanedno onswacndanounde soobeh adeaoaos 270 An average tangential section x18. Middle third of the Trenton shales at Minneapolis. Wigs. 44:to 47.” Wars MULTIPORAs NV Ale pewter s ceinecitee ati s oto ea eee ee ee ee 272 44, A tangential section x18, with very thin walls and small acanthopores. 45 and 46. Another tangential section with stronger walls and large acanthopores, x18, and several cells X50. 47. Vertical section x18. Middle third of the Trenton shales,Minneapolis. EAU END WES Y, VEE, SLAC Oe AP COONS SE PAN | Bryozoa ( VOL. II Plate XXIII. 27. CLAS VA p¥> 28 E.0.U. delet Hth te ate F > Yarn Salk UT SEER ga 2 _ oe aoe Jara a hati’ PLATE XXIV. igeas bo.) EeMrP HR A GNAY OTTAWA NSE: (MOOLG)) so cieiaictere see ereletsieters els ereieveloeiossioraieartteteierare ti cieelsinicierrcitteraete 300 land2. Two portions of a tangential section x18, showing differences due to age. 3. Vertical section <9. ; 4. Small portion of the peripheral region of the same X35. Upper part of the Galena shales, Mantorville, Minn. Survey Museum, Reg. No. 6002. Migss5)/ GOOF Emme rR A\GMCAS Ti VA'S TMi LUDIIT erareretousre rate leteieretebate eretetsvel cieietoreiorevevietelor ioral ternicraleiete raters ieteretetetetereiets 299 5. Vertical section <9. 6,7,9and14. Four tangential sections <18, exhibiting individual variations. 8. Small part of a transverse section X18. 10 to 13. The surfaces of four specimens *9, fig. 10 representing a ood average, fig. 12 the appearance of young examples, and figs. 11 and 13 the fully matured conditions. 15 to 19. A group of five specimens, three of them of the average size, while 17 is the largest and 18 one of the smallest seen. Lower third of the Trenton shales at Minneapolis, and the Galena shales near Cannon Falls, Minn. Bigs; 20it0i 23. EEE MP ERA GMAW EN OEM UR AUD IL SDD erate etal cfs Sieh eintelcealele) -lecetctels eteietelie ede fekstonsdetele eistetet eters telets 301 20. Vertical section X18. 21 and 22. Tangential sections X18, the first showing the fully matured condition, the second a younger stage in the development of the zoarium. 23. Surface of a well preserved example showing the incomplete diaphragms in the zoccial cavities, <9. Galena shales near Cannon Falls. Migs 24 FOr le STROMAL OLR VAC OiveATUAG, Mey Ds etetererarsistocerelol cterctarsiet stat evoloietaveisrebetelatcteleterelejaucietolerensterete etateietere 302 24. Surface of an old example 9. 25, Well preserved specimen consisting of several layers, natural size. 26. Small portion of one of the first layers of same X18, showing an aged condition. 27. Part of the last layer of same <18, showing appearance of surface in the youngest stage observed. ‘ ; 28 and 29. Tangential and vertical sections <18, of an example consisting of three distinct layers of zocecia 30 and 31. Another pair of sections, vertical and tangential, the latter illustrating a more aged condition than is shown in fig. 28; X18. Middle third of the Trenton shales, St. Paul and Minneapolis. GEOCMAND NAL SHE Stas URVEWED ES INNESD LAM |Bryozoa | VOL.1 Plate XXIV 10. e eo a 2 EO U delet fth The HENDERSON -ACHERT-KREBS Linw, Co.Ciwcinstan. = ry. a" PLATE XXV. Mies FO Mis) SAT OST OMAGH UE: ROTA HOU) litte iaeieteveverterareraisy slate aratstetofaceten steleloretateferetacenerel nolo siete eae eke eters land 2. A small and a large specimen. 3. Surface of the larger specimen, which is a typical example of the species, *9. 4. Tangential section, prepared from the same specimen, *18. 5 and 6. Surface of the var. circulare x9 and X18. 7. Tangential section of a speciinen with very thin walls and exceedingly small acantho- pores, X18, The shaded spaces are mesopores. 8and9. Tangential sections of two specimens of the var. circulare, X18, the first with very thick wall, the second with them thinner and in this respect agreeing with figs. 5and 6. 10. Portion of the axial region of a transverse section of a typical specimen, X18. 11. Vertical section of the natural size and a portion of same *18; typical. Lower third of the Trenton shales, Minneapolis. Re Saal 2 show bse BATOSTONGA (MEA GIN OPORAG MIB D stetsrerecatasustelsumsnsttee taeyareieiat el i-tete ven atstete (oteteisietel steers chee picts 12, A rather small specimen of the natural size. 13. Tangential section <18. 14, Part of the axial region of a transverse section X18. 15. Vertical section x9. Middle third of the Trenton shales, Minneapolis and St. Paul. IMERR OO Pa eey too ON NAOT aS) dacdoomaedat ookonteudrocotne Qao0 .bsaaushototod med adGodounGG 16 to 22. Seven figures illustrating the extreme variability displayed by tangential sections of this species; x18. Figs. 16 and 17 represent different parts of the same section, 18 shows the tubes just after bending out of the axial region, 16, 19 and 20 are of common occurrence, and 21 and 22 show extremes rarely met with. 23 and 24. Halves of two vertical sections *9, the first normal, the second indicating some disturbance in the development of the tubes. 25. One zocecial tube of a vertical section of the basal expansion 18. Middle third of the Trenton shales at St. Paul and Minneapolis. Migs 20500 28.0 DATOSROMAUMON DU OSUNE Msgs Dita cletsteisrecselste tricia ieleleectelietasitclevs ie steeietensiieie erator 26. An average specimen of the natural size. 27 and 2&. Surface of a specimen with numerous closed mesopores *9 and a small portion of same X18. In many specimens the interspaces are narrower than is shown in these figures. Upper third of the Trenton shales near Cannon Falls, Minnesota. Wigs e290 SO SA LOSTONAS HUT TMELT EY Ello) SI) cia tslet a Wetoncteied slate alaralskave(-intatore aie’ sfalekole/eloleietererstcialemeier(eiateyetalat ates 29 to 31. Three fragments of the natural size. 32. Small portion of a tangential section 18 of a specimen having asurface like fig. 34. 33. Tangential section of a less matured example X18. 34. Surface of an average fully matured example *9. 35, Surface of a young example (corresponds to the lower part of fig. 33) *18. 36. Surface of a fragment regarded as illustating a condition of extreme age, 18. Galena shales near Cannon Falls, Minn. 293 BAUD WYP, LEE, SUL NC Ut LPC OP A BEN, | Bryozoa | VOL. I Plate XXV \ a DS ae ect sos a NG E.O.U. del et Hth. THe HENDERSON-ACHERT-KREBS LiTt Co. Cincinram iy ee ie: her at PLATE XXVI. PAGE. Migs: Leto) 6: BY THOPORAEHERRICKIAU I sacnstaa sensltt cei OO. Coan ora ee ee once 263 1. Vertical section <18, showing slight irregularity in the growth. 2and 3. Tangential section 18 and a portion of same X50. 4and 5. A large and an average sized specimen. 6. Surface of the smaller <9. Middle third of the Trenton shales at Minneapolis. Hig Sai tOj9 se BYTHOPORASALCICORNIS; Na Sprccce stat ccae a eee ene eee eC eee each oe eee ee 264 7 and 8. Two specimens of the natural size. 9. Surface of the larger one x9. Upper third of the Trenton shales near Cannon Falls. Migs 10016) = HOMOTRY PEELE A (i) SUBGIRA CIGEIS M.S Daueeasticntaiic cen seas eseaciene ara en taeecls 230 10 and 11. Two tangential sections X18, showing slight differences. 12. Vertical section <18.. The structure is almost entirely destroyed and only the direc- tion of the tubes is to be made out with any certainty. 13 and 14. Two'specimens, the second a little above the average in size, 15 and 16. Surface of the larger specimen *9 and *18. Middle third of the Trenton shales, St. Paul. Bigs. Leto! HRI OTRYP- ATE SGA sins) SD iota cci a Steere ee eee ere eee omen ae eee ian eee eee nee 266 17. A group of fragments as they appear mounted on a slide. 18 and 19. Two of them x9. Upper part of the Galena shales near Cannon Falls. Wigs. 20, 21, 29and 30. ERIDOTRYPA MUTABILIS, Var: MINOR, D. Var.......02.ccee sce seccee eres eees 266 20. Three fragments of the natural size. 21. Surface of one of them x9. 29 and 30, Vertical and tangential sections *18. Galena shales near Cannon Falls. Migs:122 to28 31,132. HRIDOTRY:PA:MUDABELIG. Me ISpeecm on cmaseiise cic ciecas ceiiceneciachinee mee eee 265 22. A specimen of the average size. 23. Large example. 24. Surface of an old example presenting an unusual appearance, “18. 25. Surface of the original of fig. 23, x18. The figure includes one of the macule and ex- hibits the most common appearance of these. ; 26and 27. Tangential section x18 anda portion of same <50; represents an average fully matured condition. 28. Vertical section of the same specimen X18; shows a superficial layer of zooecia growing in a direction opposite to the first set. 31 and 32. Vertical and tangential sections <18, of an old specimen which has grown irreg- ularly causing many interspaces and thus unusually numerous and large mesopores. Galena shales, Goodhue county, Minn. Migs IB OVS. ATOSTO MAU TVAEN CHEE oO Lee arte (etre rata eieie telare lols tatereisiaiera ate best sraclec is rieieie ee teie eteleielersteietere 33. A specimen of the usual diameter. 34. Another, of large though not uncommon size. 35. .An average example of the var. nodosa. 36. Surface of a fully matured example x9. 37. Surface of the original of fig. 38 x9 and X18. (See also plate 27.) Middle third of the Trenton shales, Minneapolis and St. Paul. Wigs) 3856040. -BATOSTONEA MININESODENGE Met S De oyerc css stevie ityel-lelerseietele et ete viele «fe ieleless ctelatarayate eset 383 and 39. Two specimens, the first small, the other of the average size. 40. Surface of the larger specimen, which is in an excellent state of preservation, <9, show- ing the granulose walls. (See also plate 27.) Middle third of the Trenton shales, Minneapolis. 295 26. Plate DE NNESU TAS GiB UGA WEY, PERSE, SPU Br VOL.III eo ei UT 0:4 POD ROR z e sey ¥ 3 tes He E.O.U. delet tith 43 ters) we a : SOYA IER PLATE XXvVIl. Figs. 1 to8. BArostOMA WINCHELLI Ulr 1,2and 3. Vertical sections X18, of a young, medium, and an old specimen. 4and 5. Tangential section, X18 and <50, of the same specimen from which was prepared the vertical section shown in fig. 3. 6. Tangential section of a young specimen 18. 7and 8. Tangential section of the var spinuloswum 18 and X50. (See also plate 26.) Middle third of the Trenton shales, Minneapolis and St. Paul. : Migs woo b.wATOSTOMA (MININESOLEINSE il siSp sete siciestelacloweletoricieie ete leieleinioremcteetrst siesta aieteteie eievereneieiste 297 9and 10. Portions of a tangential section 18 and x50. 11 and 12. Peripheral and axial regions of a vertical section prepared from the same speci- men as the preceding, 18. 13. The peripheral part of a zocecial tube with fewer diaphragms than usual, 18. The true average for the species is intermediate between this and fig. 11. 14 and 15. Portions of two tangential sections, X18 and 50, in a different state of preser- vation than figs. 9and 10. (See also plate 26.) Middle third of the Trenton shales, St. Paul and Minneapolis. Wigs. 416; CORT es ATOSTOMAN (A) DECIPLEINS ste iSpseperereateacteterteiseiecistlete acisielesierereteiens esas tet taietsreleiers 298 16. Small portion of a vertical section X18. 17 and 18. Tangential section X18 and X50. In some parts of this section certain small acanthopore-like dots are distinguishable usually about midway between the angles. They are dark and scarcely half the size of the smallest shown in fig. 10. 19. From the axial region of a transverse section X18. Lower half of the Trenton shales, Minneapolis. Jess PAN ENA Din enous a WE OhoTpano DOG) Wenomdsadseensoeooos aobacos ddsudcabueahouadens 319 20. Tangential section x18. In this section the cells here drawn as open are filled with matrix, while those shaded are occupied by clear calcite. The smaller of the latter have the appearance of mesopores; on the other hand, since the preservation of the fossil is not favorable, it is possible that they represent acanthopores. 21. Vertical section of the upper extremity of same beyond the foreign body, 18. Middle third of the Trenton shales, St. Paul. Migs. 22ande23, pun PTOMR PAT INEOR MIS Mess pers niaee cysiaa aire cette a aise ee ete etet ele cieseates a ote taere 317 Tangential and vertical sections X18. Lower third of the Trenton shales, Minneapolis. Wigs. 2an dio; UEPMOTR PA AOR VU OSA. MSS) acianceocinice ea aciecn eee eerie ier elites erate 318 Tangential and vertical sections X18. Galena shales, Decorah, Iowa. Miger26/and 2 MONOTR PAN (? CHa TM TRS) CUM ULADAY My SP) ites ateieiceteisielelaleie cinteeieisteteletelsieiseiteialcicists 307 Tangential and vertical sections x9. Beneath the first the stracture of the wall is shown X35. Upper part of the Galena shales, Goodhue county, Minn. . Figs. 28 and 29. MONOTRYPA MAGNA, N. sp Vertical and tangential sections <9. “Lower Blue” limestone at Dixon, Ill. CLOMMNO RN ATAATS TAS URVENGUER INNES OCAS Plate 27. 2D << Coos aaa eek, sain — ae es oF @ ml E.0.U.del.et tith. “ ar) #4 £ 4 7 PLATE XXVIII. Figs. land 2. SPATIOPORA LABECULOSA, Nl. SP, .....eee ee cess eect eee cece cette eet e eet e eee ence ene 1. Surface, *9, of a specimen with macule of the usual size. Others may have smaller macule and more numerous mesopores between the zocecia. 2. Tangential section of Same, <18. Middle third of the Trenton shales, Minneapolis, Minn. Figs. 3 to 7. CERAMOPHYLLA FRONDOSA, D. Zen. CUSP..-. 0. see cece cece ee cece t eet cece eee eee eee eee 331 3. Nearly complete frond of this species, nat. size. 4. Small portion of its surface, x9, showing in the lower left hand corner the greater part of one of the maculz. 5and6. Small parts of two tangential sections, 18, the former illustrating the normal development, the latter an old and more irregular arrangement, and greater width of interspaces due to proximity to a macula. 7. Half of a vertical section, X18; the tubes are divided somewhat obliquely and therefore do not show the full length of the prostrate portion. Upper third of the Trenton shales, St. Paul, Minn. Figs. 8 to 11. CERAMOPORELLA INCLUSA, D. SP... - 0-00.00 eee eee e cece eee eee eee es cence eee 329 8. Surface, 9, of an example having the apertures filled with the clayey matrix. 9. Small portion of another example, *18. 10. Larger part of the surface of the original of fig. 9, <9. 11, Selected normally developed zocecium, 40, Lower and middle thirds of the Trenton shales, Minneapolis, Minn. Fig. 12. IG DRAMOPOREETALIN TERE O ROSAS ail cs P)elerlalstelaretaleteretsetelet Voie ohavatetoteletetefcteletete fol ttetelcle ese inis)-jatcaraitets 330 Surface of an average specimen of this species *18. Galena Shales near Cannon Falls, Minn. Fig. 13. CERAMOPORELLA DISTINCTA, LOE cpl Sonat ne ees te Sere ae a et Lis eS - 3828 Surface of a small specimen of this species from the lower third of the Trenton shales at Minneapolis; *18. Fig. 14. DIAMESOPORA TRENTONENSIS, 1. SP... . 0. - esses ce ee eee cence eee teen cece eee cence ent e eee 330 Two specimens of the natural size and the surface of the upper x9. The form and ar- rangement of the zocecia js a little irregular in this specimen. In others their shape approximates fig. 11. Galena shales near Cannon Falls, Minn. : Figs. 15 to 20. .ANOLOTICHIA IMPOLITA UIP... -...-.. 1. eee ee eee cece teen ee cee nee teens 327 15 and 16. Surface x9 and x18. 17. From the axial region of a transverse section *18. 18. Small portion of a tangential section X18, of a specimen in which many of the lunaria have only two tubuli. 19. Portion of a typical section X18. 20. Vertical section <9. Lower third of the Trenton shales, St. Paul and Minneapolis. Figs. 21 t0 25. ByQTHOTKYPA LAXATA Ulr.................... Gosbasdnonudsduuonaadoppasapae DSO bAGIO 325 21 and 22. Surface of a well preserved specimen <9 and *18. 23 and 24. Vertical and tangential sections x9. 25. Portion of the tangential section <18. Trenton shales, Minneapolis and St. Paul. Figs. 26 to 28. CREPIPORA SUBHIQUATA, ND. SP... see cece cece eee cece cece eee teen e en cee e eee eenes 322 26 and 27. Tangential section x9 and X18. ; 28. Vertical section <9, the entire thickness of the zoarium being shown in the right half of the figure. Upper third of the Trenton shales, St. Paul. Figs. 29 to 82. CREPIPORA PERAMPLA, D. SP....--eeseee eee sence een e eter teen cence ec eee tees ne ees 323 29 and 30. Vertical and tangential sections <9, the latter with the lunaria unusually distinct. 31. Portion of the tangential section <18. 32. Another tangential section <9, with the lunaria scarcely distinguishable. Top of the Trenton limestone, Fillmore county, Minn. BULB AED EY, EPSPS SEY Be A BN BP EN VOL.III Plate 28. 1 ry} oe Ce Scenes Ses His 460, oodvseeee San eg Pe Eee 89; etsy Ke * : waite be de Me Os E.0.U.del.et Eith CHEAP Vv. PE GOW HR SELUAREANEBRA GITOPODA OF MINNESOTA. BY N. H. WINCHELL AND CHARLES SCHUCHERT PRESERVATION AND DISTRIBUTION. In the upper third of the Trenton limestone in the vicinity of Minneapolis, brachiopods are numerous, but usually not very well preserved. This is due mainly to the dolomitic nature of the rock, and the frequent small crystals of calcite and pyrite lining the cavities of the casts. In some of the shaly layers, slabs are found, containing very fine specimens of Rhynchotrema inequivalvis, Orthis deflecta, O. sub- wquata var. conradi, Scenidium anthonensis and Rafinesquina minnesotensis. With a few exceptions, all the species of this division also occur in the Trenton shales above. In the Trenton shales, a great abundance and variety of forms of well preserved fossils can be gathered readily in the immediate vicinity of St. Paul and Minne- apolis. The greatest thickness of the shales is about seventy feet, but towards the southern part of the state they rapidly diminish, so that at Preston, which is near | the state line in Fillmore county, they are not more than fifteen feet thick. The predominating fossils of this horizon are bryozoans, and next in abundance are the brachiopods. The latter are beautifully preserved, either as entire specimens or separated valves, so that the external and internal structure of nearly all the species can be understood satisfactorily. Much can also be accomplished in the discovery of young specimens 1 mm. in size up to maturity. These small specimens cannot be picked up on the hill sides, nor on the quarry dumps, but usually where adult examples of a species are abundant, there, also, will be found all individuals from the youngest to the mature shells. Collectors discovering such localities should not fail to carry away a small sample of the shale to be washed carefully in a pan until the water is colored no longer by the residuum. After drying, what remains should be sifted into various sizes to facilitate examination with the hand lens. If the sample proves to contain young specimens, it will be only a matter of washing and [333] 334 THE PALEONTOLOGY OF MINNESOTA. {Distribution picking to secure of a species a complete series of specimens from less than 1 mm. in length to the adult size. Such series are of great value in classification, and much yet remains to be done in this direction.* A great deal can also be learned by local collectors, in regard to the evolution, introduction and disappearance of the species in these shales. Near the top of the Trenton shales, new forms are introduced gradually, so that in the overlying Galena deposits the brachiopod fauna is changed. With the intro- duction of shales containing Clitambonites diversa, the marking species of this horizon, the fauna is noticed to disagree more or less in specific expression with that of the underlying Trenton shales. A number of forms are common to both horizons, but there is a perceptible difference in them. Ascending towards the middle Galena, the older species drop out, and new ones take their places more and more rapidly. In con- nection with this faunal change, there is also a lithological one. The Trenton shales are greenish in color, but change easily to a yellow with a coarser texture, before the Clitambonites horizon is introduced. The strata then become more and more sandy in the northern exposures of the Galena, which towards the south is altered into a compact, thin-layered limestone series. Near the middle of the Galena there is another brachiopod horizon quite dis- tinct from any below it. At some localities the species found here are preserved as casts while in others the shell remains. The characteristic species of this horizon are Orthis meedsi var. germana, Rafinesquina deltoidea, Strophomena trilobata, Plectam- bonites gibbosa, Zygospira uphami, Cyclospira bisulcata, Schizotreta pelopea, and Lingu- lasma galenensis. From these beds to the Hudson River group above, the fauna is rather meager, and little collecting has been accomplished. In the upper member of the Hudson River deposits, the brachiopods are again numerous in individuals and species. Its fauna agrees with that of the upper por- tion of the Cincinnati group of the Ohio valley. The fossils are preserved in a semi- siliceous condition. Numerous outcrops of this formation occur in the southern portion of the state, but the fauna appears to be localized, and not well preserved nor abundant except in the region of Spring Valley. Below the Trenton limestone, but one brachiopod (Lingula morsit) is known in the St. Peter sandstone: none in the Shakopee formation; but several, as yet unstudied, in the Lower Magnesian. In the St. Croix formation, however, brachiopods are abundant but mainly of inarticulate species. *See “The Development of some Silurian Brachiopoda,”’ by Beecher and Clarke ; Mem. N. Y. State Mus., vol. i, no. 1, 1889 : “* Development of the Brachiopoda,” pt. i, by ©. E. Beecher, Am. Jour. Sci., vol. xli, 1891: and ** Development of Bilob- ites,” by C. E. Beecher, Am. Jour. Sci., vol. xli, 1891. BRYOZOA. 33) Treminology.] TERMINOLOY. \p edicle v. . brachialy y N oss Fra. 21. a, profile view of Orthis tricenaria Conrad; b, ventral view of Orthis tricenaria Conrad; c, cardinal view of Strophomena incurvata Castelnau. Pedicle=Ventral valve. The valve always situated on the ventral side of the animal and having the foramen or pedicle opening, except in Lingula, Obolella, etc., where the pedicle protrudes between the valves. When the shell is cemented to foreign bodies it is always by the ventral valve. It is usually the larger and deeper of the two valves in which the animal is contained. It was called the “dorsal valve” by Hall, from 1847 to about 1861; since which time “ ventral valve” has been used by him. “ Pedicle”, “neural” and “receiving”’’ valves, are synonymous terms. Brachial—Dorsal valve. The valve to which the arms or the calcified brachial sup- ports are attached. “Ventral valve” of Hall, from 1847 to about 1861. “Brachial,” “hemal” and “entering” valves, are other terms more rarely employed. post. reg., posterior region ; applies to both valves. beaks, the apexes of valves. umbo, the elevated portion of the valve immediately in front or anterior to the beaks. c.ang., cardinal angle, or angle formed by the cardinal plane with the lateral margin. lac. lateral margin, or lateral area. ant., anterior region or margin. b. v., dorsal valve. p. v., ventral valve. C. d., cardinal area of the ventral valve. del., deltidium. A plate of one piece which grows over the delthyrium of the Strophomenide, and is rudimentary in some species of Orthis. This plate begins, in the early larval stage of Thecidium, as a secretion from the dorsal side of the body segment, and becomes anchylosed to the ventral valve in the phylembryonic stage, subsequent additions being secreted by the body wall and pedicle. A plate similarin appearance, the “chilidium”’ 036 THE PALEONTOLOGY OF MINENSOTA. {(Lerminology. of Dr. Beecher,* is often present in the dorsal valve covering the car- dinal process, but its development does not begin until early nealogic or later growth, and is probably secreted by the dorsal mantle lobe. When the delthyrium of the ventral valve contains two pieces growing out from its walls, more or less uniting medially, they are called “deltidial plates”, and are deposited by the extensions from the ventral mantle lobe (see d. p., fig. 23). These plates are seen in the rhynchonelloids, spire and loop bearing genera. The pedicle opening in these forms is always situated above the deltidium or deltidial plates. @ & a ri ‘i 5 AEN Y Fig. 22. a, interior view of the dorsal valve of Orthis occidentalis Hall; 6, interior view of the ventral valve of Orthis insculpta Hall. O, (ih cardinal area. card, p., cardinal process ; this may be a thin, simple plate, or thickened and trilobed, or separated in two processes, as in the strophomenoids. dent. s., dental sockets ; the cavities into which the teeth of the ventral valve enter. cru. p., crural plates, usually forming the inner walls of the dental sockets, to which the brachia are attached. p. add. and a, add., posterior and anterior adductor scars. 0, genital [ovarian] spaces. m. sep., median septum separating the two pairs of adductor scars. del., delthyrium, a term introduced by Hall (Pal. N. Y. vol. viii) for the trian- gular space usually covered by the deltidium or deltidial plates; “ fissure” and “foramen” have also been used. (O; Ors cardinal area. On genital [ovarian| spaces. is teeth ; when they are supported by thin plates, the latter are termed “den- tal plates.” * Por a synopsis of the early embryology of the brachiopods. and «a complete discussion of the development of the delti- dium and deltidial plates, and on the term cbilidium, see “ Development of the Brachiopoda, part ii, On the Stages of Growth and Decline.” American Jour. of Science, August, 1892. BRACHIOPODA. 337 Terminology.] v., vascular sinuses. add., adductor muscle scars. did., diductor muscle scars. adj., adjustor muscle scars. When the pedicle muscular scar is present, it appears in the apex of the rostral cavity, posterior to the other scars, and is indi- cated by transverse striz. Fie. 23. a, interior view of the ventral valve of Clitambonites diversa Shaler; b, dorsal view of Zygospira modesta (Say) Hall, from which the greater portion of the dorsal valve has been removed to show the calcified brachial supports. spond., spondylium, a plate formed by the junction of the dental plates, to the upper surface of which were attached the adductor, diductor, and adjustor muscles. This plate is also present in the Pentameride. m. sep., median septum supporting the spondylium. d.p. deltidial plates. See deltidiuwm. spire, the spiral cones or calcified brachial supports. The spires may be directed toward the center of the dorsal valve or with their apices toward the lateral margins. The lamelle are usually single, but a number of genera have two bands in each spiral cone. The brachial supports also may be short or long hooks or crura to which the fleshy arms are attached, as in Ehynchonella, or they may form a more or less complicated “loop,” as in the terebratuloids. For an illustration of a loop, see the species of Hallina of this report. C.b., connecting band or loop; it is variously disposed, and of a great variety of forms growing out from each spiral cone, and may or may not join medi- ally. In Atrypa and Spirifer, the band is represented by two prongs. Protegulum, Beecher. The initial shell of brachiopods. It is smooth and of micro- scopic size, in outline semicircular or semielliptical, with a straight or arcuate hinge line and without a hinge area. Homologous to the it “protoconch” of Owen in cephalopods, and to the ‘“prodissoconch” of Jackson in lamellibranchs. 338 THE PALEONTOLOGY OF MINNESOTA. [Lingula. Nepionic, Hyatt.* The smooth shell stage succeeding the protegulum. Nealogic, Hyatt. Youthfulness, or the stage in which specific characters begin to develope. Ephebolic, Hyatt. The mature shell. Geratologic, Hyatt. Old age. It is indicated in many species of brachiopods by extreme thickness of the valves, obesity, or by numerous, crowded growth lines near the anterior margin, a condition which sometimes produces truncation and absence of stri# at the margin. Class BRAGCHVTOR@DAS (Cuvier) Dumeril. Subclass LYOPOMATA, Owen. Order ATREMATA, Beecher. Family LINGULIDA, Gray. Genus LINGULA, Bruguiére. 1789. Lingula, BRUGIERE. Histoire naturelle des Vers Testacés. 1892. Lingula, HALL. Paleontology of New York, vol. viii, pt. i, p. 2. ® Description: “Shells subequivalve, equilateral; elongate-ovate, subquadrate or subtriangular in outline; broad over the pallial region, cardinal slopes more or less conspicuous; slightly gaping at both extremities. Brachial or dorsal valve somewhat the shorter, and with a slightly thickened hinge-line. Surface of the shell smooth, or concentrically and radiately striated. Animal attached by a long, muscular pedicle protruding from between the beaks of the two valves. “Muscular impressions numerous, but usually indistinct. In the recent species they are twelve in number upon each valve, and are somewhat unsymmetrical in their arrangement. They may be designated as follows: The wmbonal impressions, produced by a single muscular band passing directly across the cavity of the shell near the beaks, and by their contraction opening the valves; the Jateral impressions, which are produced by three pairs of muscles, the anteriors passing from near the lateral boundaries of the visceral area on the pedicle [ventral] valve, forward to the anterior extremity of this tract on the brachial [dorsal] valve; the middles passing in just the opposite direction, from the anterior region of the pedicle-valve to the lateral region of the brachial; the erternals passing from the ante-lateral region of the pedicle valve to the post-lateral region of the brachial valve; these muscles serving to move the valves forward and backward. The central impressions are * Values in classification of the stages of growth and decline, with propositions for a new nomenclature,” by Alpheus Hyatt; Am, Nat., vol. xxii, p. 872, 1888. Also *‘Genesis of the Arietida.’’ Mem. Mus. Comp. Zool., vol. xvi, no, 3, 1889. BRACHIOPODA. 339 Lingula elderi.] produced by a single pair of muscles extending across the ante-lateral region of the visceral area, and by the contraction of these, the valves are closed. The transmedian impressions, are made by a triple muscle, one band of which is on one side of the visceral area, the other two on the other side, the two lateral components crossing each other in passing from the posterior region of the pedicle-valve to the medio- lateral region of the opposite valve. By the action of these muscles the animal is able to slide apart the anterior and posterior extremities of its valves. The mus- cular region in each valve is surrounded by the parietal bands, which leave more or less distinct impressions upon the shell. “The anterior internal surface of each valve bears traces of two strong pallial sinuses, which nearly meet in the axial line before reaching the anterior margin. In front and behind are radiating vascular markings. “Shell substance composed of alternating lamellw of chitinous and calcareous material. “Type Lingula anatina Lamarck.” (Hall, op. cit.) Species of this genus had their origin in the St. Croix formation,* and thence lived through all geologic times. Several species are still living, usually in shallow water, of which ZL. anatina, the type of the genus, is the most abundant and widely distributed. Lineuta ELDERI Whitfield. PLATE XXIX, FIGS. 1-4 1875-17. Lingula quadrata WINCHELL (non EICHWALD). Fourth Annual Report of the Geological and Natural History Survey of Minnesota, p. 49. 1880, June. Lingula elderi WHITFIELD. American Journal of Science, third ser., vol. xix, p. 472, figs. 1, 2. 1880, July. Lingula minnesotensis N. H. WINCHELL. Eighth Annual Report of the Geol. and Natural History Survey of Minnesota, p. 61. 1882. Lingula elderti WHITFIELD, Geology of Wisconsin, vol. iv, p. 345, pl. xxvu, figs. 1-5. 1892. Lingula elderi HALL. Paleontology of New York, vol. viii, pt. i, p. 11, pl. L, figs. 21, 22. Original description —* Shell oblong and subquadrangular in outline, with nearly or quite parallel lateral margins, which are but very slightly curved; anterior and posterior extremities subequal, the upper end being slightly angular at the apex and on the shoulders, while the front or posterior end is broadly rounded. Valves rather strongly convex, the dorsal or shorter valve being a little the more convex and the valve, as shown by the cast, frequently marked by a slight flattening, or even by a depressed longitudinal line along the middle of the front half.” Surface of the shell nearly smooth and glossy, marked by fine concentric lines of growth *This statement is based largely on professor James Hall’s late investigations as given on p. 6. Paleontology of New York, vol. viii. 1892. 340 THE PALEONTOLOGY,ZOF MINNNSOTA. [Lingula elderi. and still finer radiating lines. These give to the surface a minutely crenulated appearance; also several distinct radiating lines over the anterior half of the valves which interfere somewhat with the rounding of the concentric lines. “In the dorsal valve the impressions of the pallial sinuses [vs] are deeply marked and are widely separated, leaving the area within them very considerable; the central or inner ramifications [v] are very distinct, and the outer ones also for a short distance from the main branches, while the posterior branches show the lateral ramifications only on the outer side. The divaricator [umbonal] muscular scar of the dorsal valve [g] is very large and curved forward at the sides, being sit- uated well back near the apex of the valve. It cannot be positively traced on the ventral side, most of the specimens being imperfect at this point. The anterior adductor [anterior laterals] scars [j] are small and situated near the center of the valve, while the posterior adductors [h, central scars] are large and situated outside of and posterior to them so as to inclose their posterior ends. The adjustor [lateral, middle and transmedian]| muscles {1 i k] are distant from each other, and placed just within the posterior third of the length of the shell. Two elements can be detected in each scar on some individuals, but they are usually obscure. “On the ventral valve the lines of the pallial sinuses are nearer together on the anterior half of the shell than on the dorsal, the same as shown in JL. anatina, but spread out rapidly toward the middle, and, on the posterior half, occupy nearly the same relative position as on the other side. Near the center of the valve are seen a pair of large [central] scars [h], which have advanced from behind their track, forming a strong feature on the cast, as it originates just in front of the position of the divaricator [umbonal] muscular scar [g], and gradually widens as it advances until it occupies fully one-half of the width of the cast near the middle of its length. In the central line of these scars there is an elevated ridge, which terminates in a slightly prolonged tongue, and seems to represent the central adjustors [middle laterals, k]. The large scars outside of these are probably the posterior adductors and external adjustors combined. Posterior to these and distant from the median line are other scars, which are long and narrow, which have also left their track as they have advanced. Two elements are represented on each side, and mark the place of the posterior adjustors and anterior adductors [anterior, laterals and trans- medians, j i]. Between the lines formed by the advance of the scars of the adjustor muscles and those of the central area, on each valve, there is a narrow smooth impressed space which unites with the line of the pallial sinuses at the junction of the anterior and posterior branches, seen on all the specimens, aud for which I have not been able to satisfactorily account, as it lies within the area of the muscular scar, and consequently within the walls of the perivisceral chamber. The areas of BRACHIOPODA. 341 Lingula eva.] attachment of the muscular walls of the perivisceral chamber has not been detected, unless it be combined with the scar of the posterior branches of the pallial sinuses, which really seems to be the case. If this is so, the posterior branches of the sinuses can have had ramifications on but one side instead of on both, as in the case of L. anatina. This would be a marked specific but not a generic character,” There is considerable variation in the outline of this species, some being short and wide, while others are long and comparatively narrow. Specimens with the sheil adhering to the limestone show that the valves near the edges are considerably flattened, giving the shell a greater width than the casts of the interior indicate. These specimens greatly resemble L. guadrata, as figured by professor Hall (Pal. New York, vol. i, pl. pxx1x, figs. la. 16), and in several cases we have seen the species labeled in this way. JL. elderi can be distinguished readily from that species by the absence of a well-developed median septum in the interior of the dorsal valve. In L. quadrata Hall—L. rectilateralis Emmons, the septum is usually indicated externally by a strong central depression. By washing and picking away the adhering portion of the shell, casts of the interior of L. elderi Whitfield, can be made to show the muscular scars, and the delicate detail of the ramification of the vascular trunks. Formation and locality Common in the Trenton limestone at Minneapolis, Wanamingo, Oxford Mills, Fountain, and Rochester. Minnesota; Beloit, Wisconsin. A single example of this species was also found near the base of the Galena* shales on St. Anthony Hill, in the city of St. Paul, Minnesota. In the Salmon River or Cincinnati group at Cincinnati, Ohio, and at Covington, Kentucky. Collectors—W. D. Hurlbut, Wm. Howling, C. L. Herrick, H. V. Winchell, W. H. Scofield, and the writers. Mus. Reg. Nos. 291, 786, 3499-3503, 5009, 5010, 5061, 5133,.5668. Lineuta Eva Billings. PLATE XXIX, FIGS. 5 and 6. 1861. Lingula eva BILLINGs. Canadian Naturalist and Geologist, vol. vi, p. 150. 1863. Lingula eva BILLInes. Geology of Canada, p. 141, fig. 73. Original description: ‘Shell from one to one and a half inches in length, greatest width near the front margin, thence gradually tapering with nearly straight sides until within one-fourth of the length from the beak, from which point the sides rapidly converge to the beak; apical angle about 90°; both valves rather convex along the middle, thence descending with a flat or gently convex slope to the sides and front margin. Surface with distinct sub-imbricating concentric ridges and fine striz, and when partially exfoliated obscure longitudinal strie are visible. * For a definition of this and other stratigraphic terms consult the introductory chapter. 342 THE PALEONTOLOGY OF MINNESOTA (Lingula philomela. “The width at one-fourth the length from the beak is usually one-fourth less than it is at one-sixth the length from the front margin. The following are the measurements of a specimen of the ordinary form: “Length, 124 lines; width at 3 lines from beak, 64 lines; width at 2 lines from front, 9 lines. “The largest specimen found measures nearly one inch and a half in length.” The surfaces of the valves from the mid-length to the anterior margin are marked by a few prominent radiating, continuous, or intermittent striations. The concentric growth lines in passing the radiating strie are more or less reflexed posteriorly. Of this species we have seen but a single example in a good state of preserva- tion. It was discovered some years ago by Mr. W.H. Shelton, and is from the Trenton Shales near St. Charles in Winona county, Minnesota. The rather strongly convex valves without indications of a median depression, and the gradually diverg- ing lateral outline, will readily separate it from Lingula quadrata Hall,—L. rectilater- alis Emmons. Formation and locality.—From the Trenton shales, in section six, Fremont, Winona county, Minne- nesota. Alsoin the Black River formation of Murray bay, lower St. Lawrence river, Canada. Mus. Reg. No. 4973. Lineuta pHitomELA Billings. PLATE XXIX, FIGS. 7,8. 1862. Lingula philomela BILLINGS. Paleozoic Fossils, vol. i, p. 49, fig. 53. 1863. Lingula philomela BILLINGS. Geology of Canada, p. 161, fig. 133. 1892. Lingula philomela HALL. Paleontology of New York, vol. viii, pt.i, pl 1, fig. 8. Original description.—“ Very elongate oval; width a little less than half the length; front margin rather narrowly rounded with a small space in the middle straight or sinuate ; sides for about two-thirds the length straight or very gently convex ; the apical extremity appears to be obtusely angular, but this still remains doubtful, as no specimens with this part perfect have been collected. The shell is rather strongly convex, most prominent at or about the mid-length. There is a shallow concave sinus extending all along the median line from near the apex to the front margin. Surface with fine crowded imbricating strize of variable size, the smaller just visible to the naked eye, and the larger partaking of the nature of squamose interruptions of growth. Color in the black limestone black. A specimen in gray limestone showing the interior in a state of exfoliation is light grayish-brown, but this may be owing to some circumstance in the fossilization of the shell. “Length 16 lines; width 7 lines.” BRACHIOPODA. 343 Lingula riciniformis.] The figure of this species, as given by Billings, shows a strong median sinus, which does not reach the anterior margin, but in the description, it is said that the “shallow sinus extends all along the median line from near the apex to the front margin,” and that the latter is “straight or slightly sinuate” in the middle. Since the example before us agrees with the original description, we do not hesitate to identify this species as occurring in the Northwest. This example and the one figured by professor Hall, like the Canadian specimens, are broken along the cardinal line, and must have been “obtusely angular,” as the earlier lines of growth. are semicircular in outline, or Paterina-shaped, and not much crowded laterally. The shell substance is thick, and composed of many corneous and calcareous layers, with the surface glossy. Formation and locality.—F rom the lower portion of the Hudson River group, or Loraine shales, ina small quarry on the north side of the Upper Iowa river, about two miles west of Granger, Minnesota. Mr. E. O. Ulrich reports the species from the same horizon near Wykoff. The original specimens were found in the Trenton limestone, at Montmorenci falls, and Island of Montreal, Canada. Collector.—The specimen here figured was found by Mr. R. H. Hasse, and kindly donated by him to the survey collection, Mus. Reg. No. 7671. Lineuta RicintrorMis Hall. PLATE XXIX, FIG. 9. 1847. Lingula riciniformis HALL. Paleontology of New York, vol. i, p. 95, pl. XxX, figs. 2a, 2b, 2c. 1892. Lingula (Glossina) riciniformis HALL. Ibidem, vol. viii, pt. i, pl. I, fig. 3. Original description — Oval, convex, slightly attenuated towards the beak, which is obtuse; surface nearly smooth, or with fine nearly obsolete concentric lines. Fine radiating strive are sometimes visible; and the surface is sometimes slightly ridged, as if from elevated lines beneath the outer lamina of the shell.” Fie. 24. Stages of Lingula riciniformis. p. protegulum; o. obolella; s, nealogic. Our specimens of this species show three distinct stages of development; the first shelled condition, or “protegulum,”* which is not distinct, owing to its very *For a definition of this term, and description of the earlier stages of growth in Brachiopoda and their importance in classification, see Dr. C. E. Beecher’s valuable papers on “ Development of the Brachiopoda,” American Journal of Science, April, 1892. 344 THE PALEONTOLOGY OF MINNESOTA. {Lingula riciniformis, var. galenensis. small size; second, a very sharply defined circular stage, which is of a lighter color than the shell surrounding it. This second growth has been appropriately called the Obolella stage, and around it the shell begins to assume its specific form, growing most rapidly in the anterior region, and but comparatively little laterally and pos- teriorly. At maturity, the apex is no longer marginal, as in the Obolella stage, but has become submarginal through the addition of shell substance posterior to the protegulum. These stages of growth indicate that the course of development of Lingula is through Paterina—Obolella—Lingula. This species can be separated readily from Lingula attenuata Hall (non Sowerby) —L. daphne Billings—L. (Glossina) trentonensis Conrad, sp., by its oval form and obtuse beaks, The latter is also more attenuated towards the apex, and is now referred to the sub-genus (7lossina, Phillips. LL. elongata Hall differs in being twice the size of L. riciniformis. Formation and locality—Near the base of the Galena shales, associated with Zygospira recurvirostris Hall. A single example has been discovered at Minneapolis, while from St. Anthony Hill, a suburb of St. Paul, Minnesota, a number of specimens have been procured, Also in the Trenton at Middleville, New York, and Charlesbourg, Canada. Collector.—C. L. Herrick. Mus. Reg. No. 785. LINGULA RICINIFORMIS, Var. GALENENSIS W. and S. PLATE XXIX, FIGS. 10 and 11. 1892, Aprill. Lingula riciniformis, var. galenensis W. and S. American Geologist, vol. ix, p 284. The conspicuous differences between L. riciniformis Hall and this variety are that the former is constantly two-thirds the size of the latter, and that the greatest width is across the center of the length of the valves, while the variety is widest in the anterior third. In the Galena horizon at Oshkosh, Wisconsin, this variety is not rare, and attains twice the size of L. riciniformis Hall. Formation and locality—From the Galena shales of the north branch of the Zumbro river, at the upper bridge, near Kenyon, and near Fountain, Minnesota. Also from the Galena horizon at Neenah and Oshkosh, Wisconsin. Collectors.—W. H. Scofield and Charles Schuchert. Mus. Reg. Nos. 7672, 7673. Lineuta moprEsta Ulrich. PLATE XXIX, FIG. 41. 1889. Lingula modesta ULRicH. American Geologist, vol. iii, p. 382, figs. 4-40. Original description: “Shell small, subovate, widest in the anterior half, the width and length, respectively, in four representative cases, 3.5 to 5.2, 5.5 to 8, 7 to 10 and 7 to 11, the figures representing the dimensions in millimeters, Both valves BRACHIOPODA. 345 . Lingula clathrata.] with exceedingly little convexity, appearing in most cases, perfectly flat. Anterior third or half usually uniformly rounded. Front margin occasionally somewhat straightened. Sides gently convex to near the beak which, in none of the numerous specimens examined, seems ever to have formed an acute termination. Surface with only very faint concentric undulations; even these are quite obsolete, when the shell is preserved in a shaly or impure limestone matrix.” Formation and locality.—Rather rare near the base of the Hudson River group near Granger and Wykoff, Minnesota. It also occurs at Graf, Iowa, and Cincinnati, Ohio. Also in the middle and upper portion of the Trenton at Frankfort and Paris, Kentucky. Collectors.—E. O. Ulrich and C. Schuchert. LINGULA CLATHRATA, 7”. Sp. PLATE XXIX, FIGS. 42. This little Lingula is, in form and convexity of valves, much like L. riciniformis Hall, except that it is somewhat wider posteriorly. Like that species, this one also shows plainly the Obolella stage of growth. It is, however, much smaller than that species, besides differing from it and all associated species of Lingula in having from twenty-two to twenty-eight wavy, imbricating, transverse lines crossing the marks of growth and restricted to the external shell layer. These lines begin to appear on the medial portion of the valves quite close to the apex, or during early nealogic growth. They are closely arranged and gradually become more distant and extend across the valve from side to side. Those which are continuous from one margin to the other occupy but a small portion of the shell, becoming disunited medially at about one-third the length of the valve from the apex and cease to be developed a short distance beyond mid-length or may be continued to near the anterior margin. Interior characters not defined beyond a low median septum extending for two- thirds of the length of the shell from the apex. Length and breadth of an ordinary specimen 4.5 mm. and 2.5 respectively. The transverse surface lines appear in a number of other forms occurring in older and younger formations. The earliest species with it known to us is Lingulella stoneana Whitfield* of the St. Croix formation. The next younger one is the species here described followed by Lingula teniola Hall and Clarkey+ of the New York Clinton. The latter species possesses this feature very strongly developed, obscuring the con- centric growth lines, and “are equally visible on the inner side of the sheil, a character not seen in the other forms. Of precisely the same character is the ornamentation in L. zebra Barrande from the Bohemian Etage E.”{ JL. spathata of the Lower Helderberg also has these lines sharply developed and more closely arranged than *Geol. Wisconsin, vol. iv, p. 344, pl. xxvu, figs. 6, 7; 1882, +Pal. N. Y., vol. viii, pt. i, p. 18; 1892. #Ibid., p. 18. € 346 THE PALEONTOLOGY OF MINNESOTA. {Lingula cobourgensis. the others. In several species of recent Discinisca such as D. strigata Broderip and D. levis Sowerby the same kind of transverse lines are usually present on the ventral valve, orginating on each side of the pedicle slit, curving outwardly and terminate on the anterior third of the shell. In the above species of Lingula and Lingulella it is a constant feature in both valves, while in Discinisca it may or may not be devel- oped in the same species and when present is restricted to the ventral valve. Prof. Whitfield remarks that “the peculiar surface ornamentation of Lingulella stoneana seems to be one that characterizes many forms of this genus in the prim- ordial formations.” Since Lingula is a development from Lingulella the presence of the transverse lines in species of the former genus seems to indicate that they have acquired it through heredity rather than its being a sporadic development. If this inference is the correct one it seems to call for some recognition in a future classifi- cation of species of Lingula. Prof. Whitfield also calls attention to a homologous growth in Lucina divaricata and other pelecypods and thinks this feature to depend “on a series of changes in the mantle of the animal during the formation of the shell.” While we do not doubt this growth being due to a deposition from the mantle, yet how shell can be secreted externally, posterior to the anterior edge by a “series of changes in the mantle” is not clear. Formation and locality.—A number of specimens were found by Mr. Ulrich in the middle third of the Trenton shales at St. Paul associated with Rhinidictya mutabilis. LineuLa cosourcensis Billings ? PLATE XXIX, FIG. 12. 1862. Lingula cobourgensis BILLINGS. Paleozoic Fossils, vol. i. p. 50, fig. 54. 1863. Lingula cobourgensis BILLINGS. Geology of Canada, p. 161, fig. 132. Original description: “ Almost regularly oval; greatest width about the middle; length one-fourth greater than the width; anterior extremity uniformly rounded; apex obtusely angular; both extremities sub-equal; sides gently convex. Both valves are moderately convex, and one of them has sometimes an irregular furrow extending from near the beak along the median line for one-half or three-fourths the length. Color dark brown, with some shades of light brown or yellow; general aspect smooth and shining, with fine concentric undulations of growth, which become fine, elevated, sharp, closely crowded striw, on each side; longitudinal strie are visible on some specimens. “Length, about one inch; width, about three-fourths of an inch; depth of both valves, three or four lines. Smaller specimens occur associated with the larger.” BRACHIOPODA. 347 Glossina. ] We have two imperfect and exfoliated specimens which appear to be of this species. Lingula covingtonensis Hall and Whitfield is sometimes regarded as iden- tical with L. cobourgensis. An examination, however, will show that it is more broadly oval and has sharply elevated, rather distant, concentric lines. The striz in L. cobourgensis are fine, elevated, sharp and closely crowded on the lateral slopes, while medially there are fine concentric undulations with occasionally some radi- ating lines. Formation and locality.—Rare in the Trenton limestone at Minneapolis and Chatfield, Minnesota; Cobourg and Collingwood, Canada. Collectors.—H. V. and N. H. Winchell. Mus. Reg. Nos. 309, 3504. Sub-genus GLOSSINA, Phillips. 1848. Glossina, PuiLLirs. Memoirs of the Geological Survey of Great Britain, vol. ii, pt. ii, p. 370. 1892. Glossina, HALL. Paleontology of New York, vol. viii, pt. i, pp. 5, 6, 15. Species of this sub-genus differ from Lingula in having “an acuminate or sub- triangular form, in which the rostral area is very narrow, with long, sloping post- lateral margins, and a rounded or transverse anterior margin.” (Hall, op. ci#. p. 5.) This sub-genus is restricted to Paleozoic rocks. Lineuna (Grossina) HURLBUTI N. H. Winchell PLATE XXIX. FIGS. 18 and 14. 1880. Lingula hurlbuti N. H. WINCHELL. Kighth Annual Report of the Geological and Natural History Survey of Minnesota, p. 62. Original description: ‘ Shell ovate, broadest in the anterior half, and pointed posteriorly; the sides approaching the apex with a gentle convexity; lines tangent to sides at one-third the length from the apex, form an angle of 72°; anterior angles obsolete. The exterior surface of the shell is marked by sharply elevated concentric plications, which stand perpendicular to the shell, and on the anterior third portion five occupy the space of one line, but towards the beak they are reduced in size and increase in frequency so as to become mere striw#. Where these are largest and perfectly developed, the intervening grooves are destitute of fine striations. These plications leave corresponding lines on the interior cast when the shell is exfoliated. There are no longitudinal radiations visible on the exterior, but on the cast near the front are exceedingly dim, interrupted lines visible under the lens, that possibly have the same origin, but these do not extend more than a line and a half from the front margin, and they cannot be seen even with the lens except under a favorable angle of reflected light. 348 THE PALEONTOLOGY OF MINNESOTA. {Lingula (Glossina) deflecta. “The most elevated portion is at one-third the length from the beak, but the convexity of the valve is moderate and regular. “Dedicated to Mr. W. D. Hurlbut of Rochester, Minnesota, one of the earliest patrons of the Geological and Natural History Survey.” Recently Mr. W. H. Scofield found two other specimens of this species at the same locality in which the type was discovered. These specimens, however, add nothing to the interior characters, except that, near the anterior portion, the valves are strongly pitted, a feature, moreover, which is visible also on the type specimen. L. hurlbuti differs from L. crassa Hall,* the only species with which it need be compared, in being twice the size, and in having strongly elevated and compara- tively widely separated concentric lines of growth. In JL. erassa Hall, which also is referable to Phillips’s subgenus Glossina, the surface is described as being “appar- ently smooth, but, under a magnifier, exhibiting fine concentric and radiating strie.” Formation and locality—From the lower portion of the Galena limestone, in the quarries at Man- torville, and at Weisbach’s dam near Spring Valley. Minnesota. Collectors.—N. H. Winchell and W. H. Scofield. Mus, Reg. Nos. 393, 7674. LinavuLa (@LossinaA) DEFLECTA W. and S. PLATE XXIX, FIGS. 15-18. 1892, Aprill. Lingula (Glossina) deflecta W. and 8. American Geologist, vol. ix, p. 284. Shell of medium size, subtriangular; lateral margins diverging more or less rapidly from an acute apex, to the broadly rounded and deflected anterior third. Shell substance thick, and marked by strong, irregular, concentric lines of growth, between which are numerous finer ones. In profile the line of junction of the valves is more or less convex, dorsally. Ventral valve flat or slightly concave medially, and strongly convex transversely. On the interior of the ventral valve there is a distinct but slightly elevated median septum, which originates near the apex, and terminates somewhat beyond the center of the valve, in front of which are the small, middle lateral muscular scars. Upon each side of the median sep- tum are the scars of the progressive central muscles, which gradually expand anteriorly, and terminate just above the middle lateral impressions. The vascular trunks bound the limits of the central scars, and meet just in front of the middle lateral impressions, where they are no longer defined. In front of these scars there is a low median elevation, with a broad shallow depression on each side, the latter being anterior to the vascular trunks and slightly pitted. Numerous irregularly radiating obscure lines back of the anterior margin. * Pal. New York, vol. i, p. 98, pl. xxx, fig. 8; 1847. BRACHIOPODA. 349 Lingula:-iowensis. ] Dorsal valve strongly convex, both transversely and longitudinally. In the interior of this valve, the cardinal margin is broadly flattened, striated, and divided centrally by a well defined, narrow depression, which terminates at a point one-fourth the length of the shell from the posterior edge. Near the posterior end of this depression are faint traces of the umbonal scar. The vascular trunks are discernible on each side and anterior to the rostral depression, and having the same curve as the outer margin of the valve, thence proceed to a point somewhat beyond the pos- terior half of the shell, where they gradually converge and meet near the anterior margin. Vascular branches originate only from the outer side of the vascular trunks. The enclosed space seems to represent the tracks of the anterior and central muscular scars. The outline of this species and the convexity of the dorsal valve are variable. The broadly subtriangular specimens have more strongly convex dorsal valves than the narrow and less triangular form. There is no other species of Lingula from Lower Silurian strata having the peculiarly deflected anterior portion of the shell so characteristic of this species. Lingula linguata Hall* from the Clinton group is the only other American species with this peculiarity, and differs from L, deflecta in having parallel lateral margins. Formation and locality.—From the shales near the base of the Galena group on the farm of Ole Hansen, near Fountain, and in the Hudson River group near Spring Valley, Minnesota. Collectors.—H. O. Ulrich and C. Schuchert. Mus. Reg. Nos. 7675, 7676. LINGULA IOWENSIS Owen. PLATE XXIX, FIGS. 19-22. 1844. Lingula iowensis OWEN. Geol. Rep. lowa, Wisconsin and Illinois, p. 70, pl. xv, fig. 1. 1851. Lingula quadrata? OWEN (not Hich.). Geological Report of Wisconsin, Iowa and Minnesota, pl. mB, fig. 8. 1862. Lingula quadrata HALL. Geology of Wisconsin, vol. i, p. 46, fig. 1, and p. 435. 1868. Lingula quadrata MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 305, pl. 1, fig. 4. 1882. Lingulella towensis WHITFIELD. Geology of Wisconsin, vol. iv, p. 242, pl. rx, fig. 1. 1892. Lingula iowensis HALL. Paleontology of New York, vol. viii, part i, p. 8, pl. 1, fig. 14. Original description: “Resembles L. lamellata H., of the Niagara group, but is larger and straighter on the lateral edges. It differs from L. rectilateris [probably meant L. rectilateralis Emmons], in being flatter and not so pointed at the apex.” From the figure given by Owen, we cannot be positive in the identification of this species, but since comparison is made with JL. rectilateralis Emmons, in the * Pal. New York, vol. viii, p. 178, pl. 1vKX, fig. 5; 1892. 350 THE PALEONTOLOGY OF MINNESOTA. [Lingula iowensis. description, there can be no doubt that the name JL. iowensis was applied by him to the widely distributed and characteristic Lingula of the Galena horizon. Professor Whitfield was the first to make use of Owen’s name; the following is a copy of his description, with our additions: ‘Shell large, broadly ovate, elliptical or subquad- rate in outline, generally a little narrower above the middle of the length than below ; upper end very obtusely angular, the cardinal slopes forming an angle with each other of about one hundred and twenty degrees; sides of the shell gently rounded, and the basal line more sharply rounded, but never truncate. Valves convex, the ventral most strongly so, and generally subangular along the middle. Ventral beak projecting a short distance beyond the dorsal, and more pointed. The cardinal margins of the ventral [as well as the dorsal] valve are infolded along their border, forming an imperfect cardinal area of a very perceptible width on well-preserved specimens.” These areas are striated, and immediately below the apex of each valve, the arched striz meet, forming in the ventral valve a very slight linear elevation. Gutta-percha impressions made from natural casts of the interior of the dorsal valve show a pronounced median septum, which is but slightly developed near the posterior end of the valve, and extends somewhat beyond the center of the shell, where it is strongly elevated, and terminates abruptly. On each side of the septum, for two-thirds of its length, are well-defined, progressive, concrete lateral, and central muscular scars, In the ventral valve, the median septum is faintly indicated, and does not extend beyond the progressive, lateral muscular scars, which are one-third the entire length of the valve. In front of these impressions, at the anterior end of the septum, are the small, middle lateral scars, which extend somewhat beyond the central muscular imprints on each side. “Surface of the shell marked by strong, irregular lines of growth at irregular distances, the outer margins of which are slightly raised and free, presenting a strongly lamellose appearance under a magnifier ; the spaces between being smooth and often polished. On exfoliated specimens, and more distinctly on internal casts, the surface is very strongly radiated by fine flattened, but irregular strive for from one-third to one-half the length of the shell, and on nearly the entire width along the basal line ; but a little higher on the sides they lose their regularity and become broken and wrinkled as well as more strongly divergent.” The strizw are confined to the internal surface of the valves. Lingula cincinnatiensis Hall and Whitfield is a closely related species, and may be a direct descendant from L. iowensis Owen. It differs from the latter in being usually more robust, the valves deeper or more convex, and in having the posterior portion of the shell more pointed. BRACHIOPODA. 351 Lingula beltrami.] Lingula quadrata, as identified by Hall,* and Billings,; we regard as identical with L. rectilateralis Emmons.{ This species occurs in the Trenton, Utica slate and Loraine groups of New York and eastern Canada, and differs but slghtly, if any, from L. iowensis Owen. The characteristic striated hinge areas of L. cowensis Owen and L. cincinnatiensis Hall and Whitfield have not been observed in L. rectilateralis Emmons. Should these parts eventually be discovered in the latter species, L. iowensis Owen will then give place to L. rectilateralis, as the latter has two years’ priority over the former. Professor Hall in 1847** regarded Emmons’ species as a synonym of L. quadrata Kichwald, while Whitfield}; regarded this form as identiccal with L. iowensis Owen. We have seen four specimens of typical Lingula quadrata Kichwald from Estho- nia in the collection of Mr. Ulrich, and these prove beyond a doubt that none of the American forms identified with this species are correctly named. The Russian species is larger, with very strongly convex valves and a more narrowly rounded anterior margin than in L. iowensis, L. rectilateralis, or L. cincinnatiensis Hall and Whitfield. Formation and locality.—Throughout the Galena horizon of Wisconsin, lowa and Minnesota. Some of the more prominent localities of Minnesota are Fountain, Mantorville, Kenyon, Aspelund and Hader. From the Hudson River group near Wykoff and Spring Valley, Minnesota, Mr. Ulrich has collected four specimens which apparently cannot be separated from this species. They may, however, prove to be dwarfed or young individuals of Lingula beltrami, since this species also occurs in the above mentioned region, Collectors.—W. H. Scofield, A. D. Meeds and the authors. Mus. Reg. Nos. 2372, 3389, 7677-7680, LINGULA BELTRAMI, 2. Sp. Fie, 25. Lingula beltrami. In form and convexity of valves this species closely resembles L. iowensis, but attains a larger size with greater convexity of valves and a more subquadrate anterior margin. From L. cincinnatiensis Hall and Whitfield§ it can readily be distinguished in being wider, with valves not quite so convex and the cardinal slopes *1847. Pal. New York, vol, i, p. 96, pl. Xxx, fig. 4; p. 285, pl. LXxrx, fig. 1. +1856. Canadian Naturalist and Geologist, vol. i, p. 319, fig. 8. #1842. Geology of New York; Report of the Second District, p. 399, fig. 6. ** Loc. cit.. p. 285. 4+ Loe. cit., p. 242 § Lingulella (Dignomia) cincinnatiensis Hall and Whitfield, Pal. of Ohio, vol. ii, p. 67, pl. 1, figs. 2. 3; 1875. 352 THE PALEONTOLOGY OF MINNESOTA. (Lingula canadensis. more obtuse. The ventral valve in L. iowensis and L. beltrami is also less convex than the dorsal, while in L. cincinnatiensis and L. quadrata Kichwald (non Hall) they are equally deep, but the latter is more so than the former. In all of these species there is on the lateral slopes in the anterior half of the interior a more or less con- spicuous wrinkling of the shell which may represent the vascular markings of other species of Lingula. Formation and locality.—Four specimens have been found by Mr. Ulrich in the Hudson River group between Wykoff and Spring Valley, Minnesota. LineuLa canaDENsIS billings ? 1862. Lingula canadensis BILLINGS. Paleozoic Fossils, vol. i, p. 114, fig. 95. 1863. Lingula canadensis BILLINGS. Geology Canada, p. 210, fig. 209. 1889. Lingula? (Lingulasma?) canadensis ULRicH. American Geologist, vol. iii, p. 384. Fie. 26. Copy of Billings’ original figure of his Lingula canadensis. Original description: “Shell large, oblong, subpentagonal; front margin gently convex or nearly straight; anterior angles narrowly reunded; sides straight and nearly parallel for about two-thirds the whole length, then converging to the beaks; apical angle about 130°; cardinal edges ou each side of the beak nearly straight. The valves are moderately convex, most tumid in the upper half, descending to the sides and front margin with three flat slopes. Surface with fine, thread-like, elevated, longitudinal ridges, five or six in the width of one line at the front margin; these are crossed by much finer concentric ridges, ten or twelve in one line, which are continued over the longitudinal ridges and give to the surface a minutely nodulose appearance.” The material upon which the above identification is based is rather fragmentary, consisting of two small broken individuals, and a piece of the lateral portion of a large specimen. These are not altogether identical in outline with the figure given by Billings, but since the surface ornamentation of L. canadensis is like that of the Minnesota specimens it has seemed best to refer them provisionally to this species BRACHIOPODA. 353 Lingulasmatide. ] rather than separate them under a new name. JL. tenwigranulata McCoy* is another closely related species, but it and L. canadensis have three flattened slopes, another character not seen in the Minnesota material. Formation and locality.—Lower portion of the Galena limestone, in the quarries at Mantorville and near Hader, Goodhue county, Minnesota. The type specimens are from the Hudson River group of Anticosti. Collectors.—W. H. Scofield, E. O. Ulrich and C, Schuchert. Mus. Reg. Nos. 7681, 7682. Family LINGULASMATIDA, n. fam. Genus LINGULASMA, Ulrich. 1889. Lingulasma, ULRIcH. American Geologist, vol. iii, p. 383. 1889. Lingulelasma, MILLER. North American Geol. and Pal., p. 350. 1892. Lingulasma, HALL. Palweontology of New York, vol. viii, pt. i, pp. 24, 46. Shell subquadrate, linguliform, inequivalve; the dorsal valve considerably the deeper. Beaks apical, that of the ventral somewhat extended beyond the dorsal; cardinal margins gently sloping to the sides. Surface with the concentric striz raised at irregular intervals into points, these being arranged in radiating lines. Interior of the ventral valve with a low concave or concavo-convex platform occupying from less to more than one-half the length of the shell; the anterior wall may or may not be profoundly excavated. The ventral area has been enclosed more or less within the shell, making a distinct sheath or shelf, beneath which is the umbonal scar. Platform occupied by the progressive anterior, external and middle lateral scars. Transverse scars present underneath the platform at its antero- lateral angles. Crescentic scars scarcely defined. The dorsal valve deep, with a high platform occupying the posterior third or one-half of the valve, centrally produced into a short or very long septum. The anterior walls of the platform are more or less excavated, deepest close to the sep- tum; marked by vascular sinuses laterally directed. The crescent is more or less strongly developed, with its center sharply pointed posteriorly. In front of it is the umbonal scar, and in the type species there is anterior to the latter impression a short, sharp, median septum. Platform occupied by the lateral, transmedian, central and anterior muscular scars. Transverse scars situated at the base of the platform at its antero-lateral angles. Type: Lingulasma schucherti Ulrich. Lingulasma and Lingulops are the only linguloid genera in which interior plat- forms are developed, and in this remind one strongly of the same parts in the *See Davidson’s British Silurian Brachiopoda, p. 387, pl. U1, figs. 9-14. —23 354 THE PALEONTOLOGY OF MINNESOTA. [Lingulasma galenensis. Trimerellide. We do not regard these genera, however, as in the direct line of development towards Trimerella, but rather as a branch from Lingula, probably having its origin during Trenton times, and terminating with the Niagara forma- tion. In the Black River group, at Pauquette Rapids of the Ottawa river, in Canada, we find Obolus canadensis, and O. magnificus Billings. These species Billings subsequently referred to his genus Obolellina, now regarded as synonymous with Dinobolus, Hall. In the Galena formation of Wisconsin and Minnesota, there is another form related to the above species, Dinobolus parvus Whitfield. These species were in all probability derived from Obolella, while Monomerella and Trimerella had their origin in Dinobolus. If this opinion is the proper one, Lingulops and Lingulasma should be separated from the Lingulide and Trimerellide, and referred to a new family, the Lingulasmatide. This family will then follow the Lingulide. LINGULASMA GALENENSIS., PLATE XXX, FIGS. 1-4. 1892, April 1. Lingulasma galenensis W.and S. American Geologist, vol. ix, p. 285. Shell large, oblong, subpentagonal. Anterior margin slightly convex, and somewhat produced in the center; anterior angles narrowly rounded; lateral margins , straight, nearly parallel, rounding rapidly into the more or less convex postero- lateral margins. Ventral beak somewhat extended beyond that of the dorsal valve. Valves strongly convex, dorsal more than the ventral; point of greatest convexity, in the former at one-third the entire length of the valve from the posterior margin, in the latter nearly central. Surface of each valve with three slopes in the anterior half; the central one flat or very slightly convex, with two broad and shallow depres- ssions, causing a small central extension of the anterior margin; lateral sides very rapidly descending and somewhat convex. Surface concentrically striated; at irregu- lar intervals the strie rise into small pointed pustules radially arranged. These radial series of granulations are most prominent on the flattened, central, anterior portion of the valves; thirteen to fifteen of them in 5 mm., while twenty-eight pustules occupy the same length, measuring along a series. Interior of ventral valve with a diamond-shaped coneavo-convex platform, strongly elevated, and excavated anteriorly. Posterior margin of the specimen slightly broken; an internal arched deltidium not present. Umbonal sear (g) close to the posterior broken edge, and upon each side of it is a diverging excavated ridge. In front of the umbonal scar, and occupying the lateral portions of the platform, are the progressive tracks of the lateral (2) scars. At the posterior end of the plat- form are two slightly diverging, linear depressions, which terminate near the mid- length of the platform; and here originate two linear and parallel median elevations, BRACHIOPODA. 855 Lingulasma galenensis.] On each side of these are large shallow depressions, the middle lateral (k) scars. Transverse scars present at the base of the platform, at its antero-lateral angles. A broadly rounded, slightly elevated, median septum has its origin underneath the anterior end of the platform, and terminates at a point two-thirds the entire length of the valve from the posterior margin. The inner surface of both valves not occupied by the platform is marked by faint concentric undulations and radi- ating striations; the latter are conspicuous on the lateral portions. Interior of dorsal valve with a concave platform occupying the posterior third, more or less defined laterally, profoundly elevated, and excavated anteriorly. Anterior edge of the platform produced in the center and supported by a short septum, which terminates at about the center of the valve. Underneath the plat- form, on each side of the septum, are well-defined vascular sinuses, laterally directed. Near the apex of the posterior margin is situated a small crescent (cf), and in front of it is a well-defined umbonal (g) scar, the anterior edge of which is strongly raised above the platform. Sides of the platform occupied by the lateral (/) scars. On the inner sides of the latter are situated the central (h) scars, leaving between them a median triangular space. The anterior produced portion of the platform occupied in part by the anterior (j) muscles. At the antero-lateral angles of the platform, and indenting it, are situated the strongly defined transverse (#) scars. Length of the largest specimen, 35 mm.; width 28 mm.; thickness, 19 mm.; another specimen measures respectively 27x22x14 mm. This species differs from L. schucherti Ulrich, the only other species of the genus, in that the dorsal valve is deeper, platform and median septum shorter, and the crescent smaller. In the ventral valve, the platform is also shorter and is of an entirely different shape. The muscular scars of this species are likewise more dis- tinct than in L. schucherti, while the interior yentral area is absent in L. galenensis. The posterior margin of the ventral valve in the two specimens of this species is somewhat broken, but it is certain that this valve extended beyond the dorsal, since the outline of the latter is distinctly visible. If an enclosed ventral area had been developed in this species, such as is present in L. schucherti, there should be evidence of it in these specimens. Since there is no proof of this nature, we are of the opinion that the ventral area was mainly external in L. galenensis, and that during the succeeding geological horizon, the Hudson River group, it receded more and more internally. Formation and locality—Near the top of the Galena limestone on Pear creek, just south of Hamil- ton, Fillmore county, and near the middle of this formation near Mantorville, Minnesota. Also in the Galena limestone at Decorah, Iowa, and at Neenah and Oshkosh, Wisconsin. Collector.—Charles Schuchert. Mus. Reg. Nos, 7683-7686, 356 THE PALEONTOLOGY OF MINNESOTA. LDinobolus (%) parvus. Dinogoius (?) Parvus Whitfield. 1882. Dinobolus (?) parvus WHITFIELD. Geology of Wisconsin, vol. iv, p. 347, pl. xxvu, figs. 8-10. Fig. 27. Dinoblus (?) parvus Whitfield. A, interior of the dorsal valve as seen in a gutta-percha impression, x 2; B, profile view of a cast of the interior, with the thickness and form of the shell indicated by the outer line, natural size: C, gutta-percha impression showing the internal characters of the ventral valve, x 2; D, cardinal view of the cast of the interior, x 2. Description: Shell small for the genus, subcircular in outline, lenticular in profile, with the dorsal side somewhat more convex than the other, and both more ventricose posteriorly than anteriorly. Posterior margin broadly triangular, curving rapidly in the lateral portion to the broadly rounded anterior edge. Each valve with a narrow false cardinal area, that of the ventral valve larger and slightly produced beyond the dorsal into a samll, acute and but little incurved beak, beneath which there appears to have been a narrow, concave triangular depression. A gutta-percha impression of the dorsal side of a cast of the interior shows a large concave muscular area or platform, oval in outline and produced anteriorly into a narrow but slightly elevated mesial septum which terminates near the anter- ior margin. Upon this platform, and occupying the greater portion of it, are the progressive scars of the lateral muscles, except antero-medially where the anterior scar is present; the posterior portion is occupied by two well-defined, parallel, narrow, elongate elevations, separated by a narrow sinus, the front of which may be homo- logous with the cardinal scars, and the latter with the anal depression of Obolella. A crescent so characteristic of Dinobolus does not appear to have been developed in either valve. Platform of the ventral valve but slightly elevated, subquadrate in outline, widest anteriorly, occupied by broad progressive tracks of the lateral muscles, and separated medially by the faintly elevated median scars. Anterior edge of platform not excavated. Within the cardinal margin of the ventral valve are two short, narrow, rapidly diverging ridges, probably cardinal scars, separated by a broad but short pedicle muscle impression. BRACHIOPODA. 3b7 Dinobolus (?) parvus.] Shell substance originally not very thick, apparently smooth and now replaced by a coarsely crystallized calcite, a feature common to many species of the Trimer- ellide, Of this species we have but a single specimen from Minnesota, found by Mr, E. O. Ulrich, which is in an excellent state of preservation. The interior characters are shown in greater detail than appears to have been the case in the material from Wisconsin upon which Prof. Whitfield based the species, otherwise the example agrees with his description and illustrations. In size and form it is nearer to Dinobolus schmidti Davidson and King,* from the Lyckholmer Schicht at Kirna, Esthonia, a horizon nearly equivalent to the Trenton limestone of New York, than to Obolellina canadensis and O. magnificus Billings** from the Black River group of Canada. The latter, of which only the exterior is known, are also much larger species than D.? parvus. The interior of D.? parvus, as revealed in the Minnesota specimen, is highly instructive, since it appears to have characters both of the Obolidw and Trimerellide. The structure of the cardinal region is similar to that of Obolel/a, while the platform and its muscular scars are as in Dinobolus. The crescent so characteristic of Din- obolus is, however, absent in D. parvus. The diverging elevations on each side of the pedicle muscle sear in Obolella crassa, (the cardinal scars), are also present in D.? parvus and occupy a position equivalent to the crescent of Dinobolus. It may be that here is indicated the line of development of the crescent from the cardinal sear of Obolelia. The combination of these characters in D.? parvus seems to require its separation from Dinobolus, but until the interior is known of the species referred by Billings to Obolellina it is better to leave it provisionally in the former genus. Lower Silurian species of Dinobolus are also known from Esthonia (D. schmidti) and Brittany (D. brimonti Rouault+), but these have well-developed crescents. Formation and locality —Middle Galena, Wykoff. Collector.—B. O. Ulrich. Type in the collection of C. Schuchert. *Quart. Jour. Geol. Soe. London, vol. xxx, p. 164, pl. xix, figs. 5, 6, IS74, **Canad. Nat. Geol. vol. iii, p. 441. 1858; vol. vi, n. ser., p. 329, 1872. +See Davidson’s paper in the Geol. Mag,, vol. vii, decade ii, p. 340, 1880. 358 THE PALEONTOLOGY OF MINNESOTA. {Neotremata Order NEOTREMATA, Beecher. Sub-order DATK AULIA, Waagen. Family SIPHONOTRETIDA, Kutorga. Genus SIPHONOTRETA, De Verneuil. 1845. Siphonotreta, DE VERNEUIL. Géol. de la Russia d’ Europe et des mont. de l’Oural, p. 286. 1892. Siphonotreta, HALL. Paleontology of New York, vol. viii, pt. i, p. 110. Description —*Shell elongate-oval, inequivalve; valves inarticulated. Pedicle- valve the more convex, with a straight, elevated, conical, and perforated beak, the circular foramen opening at the apex and communicating with the interior of the shell by a tubular canal, which narrows slightly as it passes inward. No cardinal area or deltidium is present, the growth-lines passing between the beak and the posterior margin as elsewhere on the shell. Brachial valve depressed-convex; beak marginal; posterior margin regularly arched and thickened. Interior of pedicle- valve with muscular impressions confined to the umbonal region. Close alongside the opening of the sipho, just within the cardinal margin, lie two elongate scars which are accompanied on either side by broader somewhat expanded or flabellate, simple and less distinct impressions. Directly in front of the middle pair les a small central scar, inthe axis of the shell, and at either side of it a transversely elongate impression. These latter impressions are distinctly separated from the former by a transverse ridge. “In the brachial valve the impressions are equally concentrated, the entire muscular area being bounded on the posterior margin by a prominent ridge which, at the sides, merges into a compound lateral scar. The central portion of the area is much depressed and is divided axially by a narrow ridge or septum. “Shell ornamented with concentric lines and ridges, the epidermal layer bearing hollow spines, which are distended at the base. Shell-substance calcareo-corneous, the layers beneath the epidermis being punctured by radiating and branching tubules, these layers are concentric and not parallel to the internal surface. “Type Siphonotreta unguiculata Kichwald sp.” (Hall, op. cit.) SIPHONOTRETA? MINNESOTENSIS Hall. PLATE XXIX, FIGS. 23 and 24. 1892. Siphonotreta? minnesotensis HALL. Palxwontology of New York, vol. viii, pt. i, pp. 112, 177, pl. 4, figs. 37, 38. Original description: ‘Shell subovate in outline. Pedicle-valve more convex than the brachial, slightly flattened along the median line, sloping with equal BRACHIOPODA. 359 Siphonotreta? minnesotensis.] convexity toward the lateral and anterior margins. Foramen apical(?). Brachial valve depressed-convex, somewhat elevated about the umbo. Surface covered, in the umbonal region, with fine, anastomosing and gently undulating concentric lines, which, in the latter portions of the shell, are finely granulose or serrated; at about one-third the length coarser varieties of growth appear, between which the finer lines are retained. Surface covered with hollow spines of various sizes, which appear to have been mostly set over the umbonal region of the pedicle valve. Here, where the growth lines are absent, the spine-bases in the original specimen are large and all of about the same size, and are disposed without order. Over the other portions of the shell the spines are set along the edges of the varices, small and large being indifferently mixed. The bases of the spines make annular swellings on the interior of the valve. The length of the original specimen is 15 mm., width, 12 mm.” Since no additional material has been discovered other than that used by professor Hall, we give in addition his observations on the species, with its relations to a similar form which is tentatively referred by him to Schizambon. “The American paleozoic faunas have yet furnished no thoroughly satisfactory representative of Siphonotreta. Before us are two specimens of a form allied to, but probably distinct from the Canadian representatives of Schizambon (?), referred to on a following page [Siphonotreta scotica Whiteaves—Schizambon fissus var. canadensis Ami (Hall) ], which have been collected by Mr. Charles Schuchert and Mr. E. 0. Ulrich, from the Trenton limestone at Minneapolis, Minnesota. One of these is an exterior mould, the other retains both valves, though the umbonal part of the pedicle valve has been broken, leaving no indication of the character of its foram- inal aperture. The shell differs somewhat from the Canadian specimens in outline, being broader over the pallial region; the brachial valve shows a low longitudinal depression, the shell substance is very thin, while in the other species referred to, it is remarkably thick, and its lamellose structure conspicuously developed; the ornamentation of the surface consists, not of sharp, concentric lines, broadening to ridges toward the margin, but of fine, concentric, anastomosing wrinkles, which are interrupted over the body of the shell by the edges of the spiniferous lamella; the spines are comparatively short and sparse. Though recognizing the difficulties in the discrimination of species of Siphonotreta, we are nevertheless disposed to regard the above mentioned features as of specific value; and in the absence of evidence determining the character and position of the pedicle passage, it seems judicious to leave the species for the present under the genus Siphonotreta, with the designation Siphonotreta minnesotensis.” Formation and locality—From the Trenton limestone near the University of Minnesota, Minne- apolis, Minnesota. Collectors.—E. O. Ulrich and Charles Schuchert. 360 THE PALEONTOLOGY OF MINNESOTA. (Lingulellida. Family LINGULELLIDA, Schuchert, LEPTOBOLUS OccIDENTALIS Hall. 1871. Leptobolus occidentalis HALL. Description n. sp. Foss. from the Hudson River group, p. 3, pl. 1m, fig. 18. 1872. Leptobolus occidentalis HALL. Twenty-fourth Report N. Y. State Cab. Nat. Hist., p. 227. pl. vu, fig. 18. 1892. Leptobolus occidentalis HALL. Pal. N. Y., vol. viii, pt. i, pl. m, fig. 7. This species will probably be found in the lower portion of the Hudson River group of Minnesota, since it occurs in abundance in Iowa and Wisconsin. Mr. E, 0. Ulrich has collected one specimen which may prove to belong to this species, but its position is such as to leave its identity in doubt. Formation and locality.—In the lower portion of the Hudson River group at Hawley’s mills or Graf, Iowa; Plattville and Clifton, Wisconsin; Ottawa, Canada(Ami). The specimen from Minnesota was found three miles north of Spring Valley. Genus SCHIZAMBON, Walcott. 1884, Schizambon, WALCoTT. Monograph U. S. Geological Survey, vol. viii, p. 69. 1887. Sehizambonia, (XHLERT. Manuel de Conchyliologie, Fischer’s, p. 1266. 1892. Schizambon, HALL. Paleontology of New York, vol. viii, pt. i, p. 113. Original description: ‘Shell ovate or oblong-oval, inequivalve; valves inarticu- late; larger or ventral valve most convex, with a short obtuse beak at the cardinal margin. Foramen oblong and opening on the summit of the valve; no area nor deltidium; cardinal edge thin; smaller or dorsal valve nearly as convex as the larger, slightly flattened along the median line. “Structure calcareo-corneous, consisting of a nacreous outer layer with a closely attached inner calcareous layer. Both layers are thought to be punctured by scat- tering spines apparently on the outer edges of the lamin or lines of growth. “The interior of the larger valve shows the oblong foramen in a slight elongate depression and a pair of muscular scars just in front of it on each side of a slight longitudinal depression; from near the beak on each side of the foramen, a shallow sharply defined depression extends obliquely outward. No other markings were observed. In the interior of the dorsal valve a pair of anterior central muscular scars terminate their path of advance from the beak, a slight rounded ridge rising on the central line; posterior to these a large pair occur, and still beyond and more posterior a third pair, a narrow rounded edge extending obliquely down from the beak on each side between the central and lateral scars.” Type Schizambon typicalis Walcott. Since the interior characters are unknown in Schizambon? dodgit, n. sp., and S.? lockit. n. sp., these forms are placed in this genus provisionally. S. typicalis is BRACHIOPODA. 361 Schizambon(?) dodgii.] said to have a short, obtuse beak at the cardinal margin, and judging from the illus- tration, it seems that little growth took place posterior to the protegulum, or initial shell. While no mention is made in S. fypicalis and S.? /fissus var. canadensis Ami, of shell growth posterior to the protegulum, yet undoubtedly this feature will be found when looked for in specimens preserving these parts. The line of development was probably as follows: From Paterina to a form having an open pedicle notch at the posterior end as in Schizocrania and Trematis, next to one where this notch is closed, leaving a more or less circular excentric pedicle opening, as in Acrothele or Acrotreta; thence to Schizambon. ScHIZAMBON(?) DODGII, ”. sp. PLATE XXX, FIGS. 57. Shell broadly oval, or nearly circular in outline. Dorsal valve evenly convex laterally and anteriorly; deeper than the ventral valve; point of greatest elevation about mid-length; centrally it has a shallow, concave, narrow sinus, which has its origin at the beak, thence slowly expanding in width, and traversing the entire length of the valve. Surface with numerous, concentric, variously terminating growth lines. Near the beak these lines indicate a Paterina-shaped nepionic stage. They are very delicate, the shell appearing smooth and shining, and gradually assume the contour of the mature outline of the valve, becoming stronger and stronger as full development is attained. Every second, third, or fourth line prom- inent, strongly imbricating, wavy along the edges, and terminating in long, slender, hollow(?), radiating spines. The intermediate concentric lines between the spinif- erous ones are sharply elevated and finely crenulated. The spines begin to develop at a very early age, are remote, but become more and more crowded toward the anterior margin, where there are about sixteen in 3 mm., with an average length of 2 mm. Ventral valve somewhat larger than the dorsal; curvature along the center not very marked, with the lateral slopes broadly convex. Beak marginal, slightly pro- duced, elevated, with a small, false cardinal area beneath it. Pedicle furrow origi- nating at the beak, narrowly triangular, 4 mm. in length, becoming deeply concave, with an opening into the interior of the shell, probably at its inner end. The nature of this opening and the interior characters of both valves are unknown. At the apex, the concentric lines are first Paterina-shaped; then growth obtains all around the initial shell, being more rapid anteriorly than posteriorly. It is during this second stage that the false cardinal area is formed, and the position of the pedicle opening changed. After the initial shell, the first few lines of growth 362 THE PALEONTOLOGY OF MINNESOTA. (Schizambon(?) lockii. along the posterior margin do not pass over nor around the pedicle, but stops on each side; therefore during this period, there is an open pedicle slit, which is after- wards closed posteriorly by the addition of shell matter underneath the pedicle. As the pedicle opening advanced, the shell was resorbed anteriorly, and a deposit formed posteriorly, as indicated by the strong convex lines in the pedicle furrow. Schizambon ? dodgii differs from S. ? fissus, var. canadensis Ami*, in being smaller, more broadly oval, in having a dorsal sinus, and the spines shorter, thicker, and therefore less numerous. If Siphonotreta? minnesotensis Hall should prove to belong to Schizambon, it will still be found to differ from S.? dodgii in the much thicker spines and the many large openings in the shell on the posterior portion of the dorsal valve. Formation and locality.—Two specimens and fragments of others were collected by Mr. W. W. Dodge, of Cambridge, Massachusetts, for whom the species is named, in a dark, compact limestone near the top of the Trenton at Sandy Hill, New York. Associated fossils are Trematis terminalis Emmons, and Trinucleus concentricus Eaton. The types were kindly presented to one of the writers. SCHIZAMBON(?) LOOKII, 2. sp. PLATE XXX, FIGS. 8-10. Shell large, very thin and broadly oval in outline. Dorsal valve shallow, not as deep as the ventral, and evenly convex laterally and anteriorly. Surfaces shining, nearly smooth, marked by fine, concentric growth lines and delicate, radiating strie. At the apex the former are Paterina-shaped, but after this stage growth takes place more strongly anteriorly than laterally, which soon gives to the shell its specific form. At about two-thirds the length of the shell from the beak to the anterior margin, the fine, radiating strie have numerous, very small, elongate, but distinct pustules, which probably did not terminate in spines. Ventral valve most elevated at the beak, with gradual slopes laterally and anteriorly, and abrupt ones posteriorly. Apex obtuse, situated at about one-sixth the length of the shell from the posterior margin, with the pedicle furrow originating at the highest point, and gradually widening and extending forward not quite to the center of the valve in the smaller specimens; while in the larger it terminates at one-third the length of the shell from the posterior margin. Surface marked by concentric, slightly elevated growth lines, a number of which continue around posterior to the apex, and gradually become more distant and prominent as growth progresses. On each side of the pedicle furrow are a few radiating strie, while in front of the former the concentric growth lines have numerous, very small but dis- tinct tubercles, about ten in 38 mm., which are probably the bases of former spines. *Ottawa Naturalist, Dec. 1887; see also Pal. N. Y., vol. viii, p. i, p. 115, pl. 4, figs. 32-36, 1892. Bn aat BRACHIOPODA. 363 This species is readily separated from all other American species now referred to the genus by its thin valves, and particularly by the absence of all spines and imbricating growth lines on the posterior two-thirds of the dorsal valve. This species may prove to be the type of a new genus with relations nearer to the Discinide than with the Siphonotretide. Formation and locality. —Two specimens have been procured, one of which, showing more of the detail, was recently collected by Mr. F. W. Sardeson on top of the hill just north of the Cincinnati Uni- versity, in beds XIIb of Mr. Ulrich’s subdivision of the Cincinnati group. The specific name is given in remembrance of the pioneer geologist, John Locke, of Ohio. Family DISCINIDA, Gray. Genus ORBICULOIDEA, d’Orbigny. 1850. Orbiculoidea, d’ORBIGNY. Prodrome de Paleontologie, vol. i, p. 44. 1890. Orbiculoidea, HALL. Paleontology of New York, extract vol. viii, pt. i, p. 129. Description: “Shells subcircular or subelliptical in outline, inequivalve. Apices eccentric. Pedicle-valve depressed convex, or flattened, with the apex slightly ele- vated and inclined posteriorly. On the exterior of the valve a narrow pedicle-furrow, abruptly intercepting the ornamentation, but not penetrating the substance of the shell, begins just below and behind the apex, extends over a greater or less portion of the radius of the valve, and, at its distal end, is produced into a short tubular sipho, which traverses the substance of the shell obliquely backward, emerging on the interior surface, where it produces a narrow groove, and usually terminates before reaching the margin of the valve. On the interior, the position of the external groove is marked by a thickened ridge extending from the apex, and this is continuous with the thickened margins of the internal groove, which, in advanced age, may become so developed as to envelop this groove, except at its outer end. “The larger or brachial valve is depressed-conical, with the apex more strongly directed backward than in the opposite valve. The interior shows a fine longitudinal ridge or septum extending from the apex forward. Otherwise the internal markings are not satisfactorily known. “Shell-substance composed of alternating lamelle of corneous and mineral matter, the latter often removed in fossilization, making the shell appear essen- tially phosphatic. Surface ornamentation usually consisting of fine, crowded or distant, sometimes lamellose concentric lines, occasionally crossed by radiating lines or ridges. “Type: Orbicula morrisi Davidson.” (Hall, op. cit.) 364 THE PALEONTOLOGY OF MINNESOTA. ([Orbiculoidea lamellosa. The species now referred to this genus were formerly regarded as congeneric with the recent species Discina striata Schumacher, the type of Discina. So far as known that genus is restricted to a single species, all the other recent forms formerly referred to Discina now belonging to Discinisca, Dall. Other Paleozoic subgenera of the same type of structure as Orbiculoidea are Schizotreta, Kutorga, Gthlertella, Lind- streemella and Remerella, Hall. ORBICULOIDEA LAMELLOSA Hall ? PLATE, XXIX, FIG. 25. 1847. Orbicula lamellosa HALL. Paleontology of New York, vol. i, p. 99, pl. xxx, fig. 10 (not Orbicula lamellosa Broderip, 1833=Discinisca lamellosa). 1855. Orbicula truncata Emmons. American Geology, part ii, p. 200, fig. 62. 1860. Discina truncata Emmons. Manual of Geology, p. 99. 1862. Discina circe BILLINGS. Paleozoic Fossils, vol. i, p. 51, fig. 125. 1890. Orbiculoidea lamellosa HALL. Paleontology of New York, extract of vol. viii, pl. 1vE, fig. 12. Original description: “Orbicular, depressed; apex small, but little elevated, situated about one-third the breadth of the shell from the margin; surface marked by elevated lamelli-form concentric lines or ridges.” The following is Mr. Elkanah Billings’ description of Discina circe, a species now regarded as a synonym of O. lamellosa: “Cireular; lower [ventral] valve with the apex central or nearly so; peduncular groove acutely oval, extending from the apex about two-thirds the distance to the margin. The foramen is probably situated at the outer extremity of the groove, but it cannot be seen in the specimen examined. The upper [dorsal] valve (sup- posed to be that of this species) has the apex situated about one-third the semi- diameter from the margin. In both valves the apex is smooth. “Surface with rather strong, sublamellose concentric strie, which become more distant and coarser from the apex outwards. At the margin there are four or five ridges in one line, but next to the apex double that number in the same space. The ridges are somewhat irregular, being in some places slightly undulated, and occasionally branched, two or more running into one. The grooves are rather wider than the ridges, and the lamellose aspect of the latter appears to be due to their being more abruptly elevated on the inner side, or the side towards the apex, than on the outside. “Width of the specimens of the lower valves examined, nine lines; length of peduncular suleus, three and one-fourth lines; width of the same, one-half line. Another specimen (an upper valve) is seven lines wide. “The lower [ventral] valve is depressed, conical and appears to have been about two lines in hight, but as it is somewhat distorted by pressure, the true elevation can- not be determined. The upper [dorsal] valve seems to be Jess convex than the lower.” BRACHIOPODA. 365 Schizotreta] The single specimen which is here referred, with some doubt, to this species is a dorsal valve about 4 mm. in hight. The apex is nearly central, with the anterior slope strongly convex, while the posterior slope is slightly concave. Formation and localityx—From the Salmon River (Hudson River) group or Loraine shales near Spring Valley, Minnesota. Also in the Trenton formation at Middleville and Lowville, New York; Bellville and Ottawa, Canada. Collector.—Charles Schuchert. Genus SCHIZOTRETA, Kutorga. 1848. Schizotreta, Kurora@a. Verhandl. der russ.—Kais. Mineral. Gesellsch. zu St. Petersburg, 272, 2 1890. Schizotreta, HALL. Se as New York, vol. viii, abstract, p. 135. This subgenus is readily distinguished from Orbiculoidea “in having the perfor- ated valve very convex and the imperforate one depressed-conical or flat. “The pedicle-groove has essentially the character seen in Orbiculodea, d’Orbigny, but is usually much more distinctly retained on account of the greater thickness of the shell. “Muscular impressions of the brachial or imperforate valve in Schizotreta conica Dwight, consist of two strong excavated anterior adductors approaching toward the center of the shell, and separated by a prominent septum which is continued from a somewhat thickened posterior muscular area.” (Hall, op. ct.) Interior of ventral valve with the posterior adductor scars situated on each side of the walls of the pedicle groove. SCHIZOTRETA PELOPEA billings, sp. PLATE XXIX, FIGS. 26-28. 1862. Discina pelopea BILLINGS. Paleozoic Fossils, vol. i, p. 52, fig. 56. 1863. Discina pelopea BILLINGS. Geology of Canada, p. 159, fig. 124. 1892. Discina concordensis SARDESON. Bulletin of the Minnesota Academy of Natural Science, vol. iii, p. 328, pl. 1v, figs. 13, 14. Original description: “Upper valve circular, depressed-conical. Apex about half the semi-diameter from the posterior margin. Surface with fine concentric strize when perfect, but when partially exfoliated, smooth and places shining. Color black; width, six lines. Lower valve unknown. The following emended description is prepared from a series of specimens obtained from the quarries at Mantorville, Minnesota, in the Galena limestone horizon: Shell circular, biconvex, with the apex of the dorsal valve situated at about one-third the entire length of the shell from the posterior margin; apex of the ventral valve somewhat more excentric. Surface with numerous concentric, strongly elevated lines of growth, with the intermediate spaces wide and concave; 366 THE PALEONTOLOGY OF MINNESOTA. (Schizotreta minutula. thirteen to fifteen in the space of 2mm. Dorsal valve depressed-convex. Ventral valve strongly elevated at the apex, perforate; posterior slope rapid, convex; anterior slope flat, or slightly concave. Pedicle opening short, narrow, oval and surrounded by an elevated margin. In the interior, on each side of the pedicle area, are situated the very narrow posterior adductor scars. The margin of this valve is distinctly, but slightly reflexed, producing a broad, shallow groove along the outer margin of the natural casts. ‘This species differs from Discina circe Billings—Orbiculoidea lamellosa Hall, in having the ventral valve more elevated, while in the latter it is the shallower valve that has the pedicle opening. The apices of the valves also are much more excentric in S. pelopea than they are are in Hall’s species, being very nearly central in the latter. From Schizotreta conica Dwight, and S. ovalis Hall, it differs in being in outline and not narrowly oval. Formation and locality.—Not uncommon in the Galena limestone, just above the Galena shales, in the quarries at Mantorville and at Old Concord, Minnesota. Also from the same formation at Dubuque, Iowa, and Neenah, Wisconsin. From the Salmon River (Hudson River) formation at Spring Valley, Minnesota. Also in the Trenton limestone at Montreal, Canada. Collectors.—A. D. Meeds and the authors. Mus. Reg. Nos. 263, 296, 7688-7690. SCHIZOTRETA MINUTULA, 7. Sp. G Fig. 28. a, dorsal valve; 6, ventral valve; e¢, profile view; d, interior of dorsal valve; all x 18. Description: Shell minute, nearly circular in outline, marked by numerous, delicate concentric lines of growth and sometimes a few radii, in the anterior region; valves about equally convex. Ventral valve with a minute circular pedicle opening in the apex of the shell. Area posterior to the dorsal beak more excavated than that of the other valve. Interior of the dorsal (?) valve apparently with two pairs of muscle sears, the posterior pair the larger, diverging forward and situated one on each side of the beak cavity; the other pair is placed medially near the lateral margin. Dimensions, > of a millimeter in length. This little species is the smallest adult brachiopod from paleozoic rocks known. Individuals occur in abundance associated with stems of Diplograptus, to which they were probably attached. This may account for their small size. Formation and locality.—From the lower portion of the Hudson River group near Granger, Minnesota, Mus. Reg. No. 8392, BRACHIOPODA. 367 Trematis. | Genus TREMATIS, Sharpe. 1847. Trematis, SHARPE. Quarterly Journal Geological Society, vol. iv, p. 66. 1892. Trematis, HALL. Paleontology of New York, vol. viii, pt. i, p. 138. Description: “Shell subcireular or transversely oval in outline. Pedicle valve unevenly convex, more or less depressed over the posterior region; apex at or behind the center; directly beneath it begins the pedicle-fissure, which transects the shell, vertically widening to the posterior margin with straight or outwardly-curving edges. Brachial valve evenly convex, with its apex marginal and slightly projecting. On the interior, the pedicle-valve shows a faint median furrow extending from the angle of the fissure to the apex of the shell; this groove widens at its apical termina- tion and may represent a point of muscular attachment. The sides of the fissure are often thickened by callosites similar to those sometimes seen in species of Orbiculo- idea. From the apex of the valve extend radiating and branching vascular sinuses. “In the brachial valve the posterior margin is much thickened and broadly grooved to allow the extension of the pedicle. This thickening does not take the form of a cardinal area or shelf, but is rather a callosity closely appressed against the interior surface of the shell, the central portion being projected beyond the margin of the pedicle-valve. Directly below and in front of this area are two transversely elongate scars, adjustors or posterior adductors, which are usually partly concealed by the progressive overgrowth of the cardinal thickening. A faint median septum begins between these scars and passes forward, becoming more prominent over the tongue-shaped median elevation which separates the large central scars. These impressions are oblique and are not simple, each appearing to be composed of two, if not three distinct scars, making a posterior, a median and an anterior pair. What appears to be the posterior pair is small, and sometimes quite sharply defined, the central pair very much larger, and the anterior pair narrow, situated at either side of the angle of the median callosity and separated by the apex. The specialization of the first of these scars is not satisfactorily estab- lished; the entire impression is deeply excavated. In some well preserved speci- mens there is also evidence of external marginal scars lying just in front of the outer end of the posterior adductors. “Surface of both valves more or less completely covered by a beautiful orna- mentation consisting of punctures or small pittings of varying depth, arranged either in quincunx (T°. terminalis) or in radiating rows; in the latter case they may be distant from one another without intervening ridges (7. wmbonata), or lie in radi- ating furrows, when they are either circular (T. punctostriata) or subrectangular (7. ottawensis). 368 THE PALEONTOLOGY OF MINNESOTA. (Trematis huronensis. “Shell-substance composed of an outer calcareous layer with a series of inner corneous lamelle. The outer layer varies in thickness in different species and is coarsely punctated by the pittings constituting the surface ornamentation. The corneous layers are impunctate.” (Hall, op. cit.) Type: Trematis terminalis Sharpe (not Emmons)—’. millepunctata Hall. TREMATIS HURONENSIS Billings ? Fig. 29. Billings’ original figure of 7. huronensis. a, lower valve. b, longitudinal section, showing the curvature of both valves; ¢, a portion of the surface enlarged. 1862. Trematis huronensis BILLINGS. Paleozoic Fossils, vol. i, p. 53, figs. 59a, 59b, 59c. 1863. TVrematis huronenis BILLINGS. Geology of Canada, p. 159, figs. 130a, 130c. 1892. Productella minneapolis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 332, pl. Iv, figs. 11, 12. Of Trematis we have seen but four imperfect specimens. Since they preserve only the dorsal valve, no direct comparison can be made with the ventral valve of T. huron- ensis Billings, and therefore this identification is provisional. The surface pittings in these specimens are similar to those in 7. huronensis, i. e, they are arranged in radiating lines, not in quincunx, and in this respect differ from 7’ terminalis Emmons, T. millepunctata Hall, and T. quineuncialis Miller and Dyer. Our specimens vary somewhat from Billings’ species, in that the radial surface depressions become obsolete towards the anterior margin. The “ventral valves” of Productella minneapolis Sardeson are identical with the upper or dorsal valve of the shells identified by the writers with Trematis huronensis. Moreover, Productella is not known below the Devonian. Formation and locality—From the Trenton limestone in the quarries along the river bluffs, aad near the base of the Trenton shales at Minneapolis, Minnesota. The Canadian specimens are from the Black River limestone of Pallideau islands, lake Huron. Collectors.—C. L. Herrick and C. Schuchert. Mus. Reg. No. 7691. BRACHIOPODA. 369 Trematis ottawensis.] TREMATIS OTTAWENSIS Billings. Fie. 30, Billings’. original figure of JT. ottawensis. 1861, Trematis ottawensis BILLINGS. Paleozoic Fossils, vol. i, p. 53, fig. 58. 1892. Trematis ottawensis HALL. Palxontology of New York, vol. viii, pt. i, pl. 1vG, figs. 15-17. Original description: “Nearly circular; length a little greater than the width; upper valve moderately and uniformly convex, most elevated about the middle; apex small, obtusely pointed, slightly elevated, marginal. Surface with fine, radiating striz, which increase by interstitial addition, sometimes closely crowded together, in which case there are ten or twelve in the width of one line; occasionally more distant, or from four to eight in one line. The intermediate grooves are divided into square compartments by cross-ridges, which connect the radiating ridges, but are not con- tinuous, those in one groove not corresponding in position with those in the adjacent grooves, so as to form uninterrupted concentric lines. In specimens with the striz closely crowded together only the radiating lines are distinctly visible, but the others can always be detected in good specimens, on close examination. “Length from twelve to fifteen lines; width a little less than the length. Lower valve unknown.” Formation and locality,—Rare in the’Galena beds at. St, Anthony hill, St. Paul. Also in the Trenton limestone, Ottawa, Canada, and at Frankfort, Kentucky. Collector.—E. O. Ulrich. Genus SCHIZOCRANIA, Hall and Whitfield. 1875. Schizocrania, HALL and WHITFIELD. Paleontology of Ohio, vol. ii, p. 73. 1892. Schizocrania, HALL. Paleontology of New York, vol. viii, pt. i, p. 142. r Description: ‘Shells subcircular in outline, inequivalve, unarticulated. Pedicle valve flat or concave; apex subcentral. A deep triangular notch extends from just behind the beak to the margin, where its are is equal to about one-sixth of the periphery. The apex of this broad pedicle-notch is occupied by a triangular trans- verse plate varying in size with the age of the shell, but extending for one-fourth to one-third the length of the opening. Surface marked by concentric-growth lines. On the interior no muscular impressions are visible. Brachial valve more or less —24 370 THE PALEONTOLOGY OF MINNESOTA. |Schizocrania filosa. convex, with the beak marginal. The interior bears a pair of strong posterior adductor scars, lying close together in the umbonal region; their outline is elongate- ovate, indicating a progressive increase in size, and they frequently appear to be divisible into anterior and posterior elements. In front of them, at about the center of the valve, are the small and faint anterior adductor impressions. A low median ridge extends from the apex to beyond the center of the valve. External surface marked by elevated strive radiating from the beak. “Substance of the shell composed of perlaceous calcareous lamin which con- stitute the most of the shell. The inner layers appear to be corneous. All are impunctate?” (Hall, op. cit.). Type: Orbicula? filosa Hall. Species of this genus are found in the Trenton, Utica and Hudson River groups of America. S. helderbergia Hall, from the Lower Helderberg, and S. superincreta Barrett, of the lower Oriskany, are other American species. Scuizocranta FiLosa Hall, PLATE XXIX, FIGS. 29-81. 1847. Orbicula? filosa HALL, Paleontology of New York, vol. i, p. 99, pl. Xxx, figs. 9a-9d. 1863. Trematis filosa BiLuines. Geology of Canada, p. 159, fig. 126. 1873. Trematis filosa HALL. Twenty-third Rep. N. Y. State Cab. Nat. Hist., pl. xn, figs. 21, 22. 1875. Trematis (?) filoca MiLLER. Cincinnati Quart. Jour. Sci., vol. ii, p. 15. 1875, Schizocrania filosa HALL and WHITFIELD. Paleontology of Ohio, vol. ii, p. 73, pl. 1, figs. 12-15. 1892. Schizocrania filosa HALL. Paleontology of New York, vol. viii, pt. i, p. 143, pl. 1vG, figs. 22-30. Original description: “Orbicular; one valve more or less convex; apex marginal; surface radiated with numerous fine elevated thread-like striae which are more or less prominent, depending on exfoliation of the shell; intermediate striz coming in between the others as they recede from the beak; but the striz are not bifurcate.” This species was subsequently more fully described by Hall and Whitfield from material obtained at Cincinnati, Ohio. The description is as follows; “Shell orbic- ular, or very slightly ovate, the beak of the upper or free valve [dorsal] projecting a little beyond the limits of the circle, giving a somewhat greater diameter along the median line than in a transverse direction. Free valve moderately convex, the central region being the most prominent. Attached valve [ventral] discoid, very thin, deeply and broadly notched on the posterior side; the notch not extending quite to the center of the valve; occupying nearly one quarter of the circumference of the valve on the outer margin; border of the notch thickened, especially at the base, which is rounded and the center marked by a slightly projecting point. Inter- ior of the free valve [dorsal] marked by two proportionally large, elongate, ovate, diverging muscular prominences [posterior adductor scars], leaving corresponding pits on the casts of the shell, or on exfoliated specimens; situated just below the BRACHIOPODA. 371 Schizocrania filosa.] beak, and extending nearly or quite one-fourth of the length of the valve from the apex. There are also two other muscular impressions [anterior adductor scars] smaller in size, circular in form, and situated near the middle of the valve below the extremities of the ovate imprints, and slightly more distant from each other. Beneath the beak there is a slight thickening of the cardinal border. The muscular markings of the lower valve have not been observed. “Surface of the shell of the convex valve [dorsal] marked by fine, even, thread- like radiating strie; increased both by division and implantation, and gradually increasing in strength toward the border of the shell; the interspaces where the shell is perfectly preserved are flattened, the strie appearing as raised lines on the surface. The attached valve [ventral] is strongly marked by irregular concentric undulations circling the valve parallel to the margin, but interrupted at the border of the notch.” When the dorsal valve is broken away so as to show the ventral valve beneath, it is seen that the first overlaps and completely surrounds the latter, and it may, as believed by Hall, (op. cit. 1892, p. 143), have served as “an important accessory means of attachment” to foreign bodies. This species is usually found attached to brachio- pods, particularly to Rafinesquina alternata, but is occasionally found on gastropods, as in the case of the Minnesota specimens before us. Fig. 31. a, three immature specimens attached to Strophomena, natural size; b, two of the same x 7; c, same x 18. Middle third of the Trenton shales, Minneapolis. Collection of C. Schuchert. These figures are introduced to show various stages of the nepionic and early nealogic condition of Schizocrania. The “Paterina stage,’ with its straight hinge- line, continues throughout the nepionic growth and is succeeded in the early nealo- gic stage by the development of series of radially arranged pits strongly resembling those of Trematis. This is followed by the striated or specific stage. Schizocrania, therefore, seems to be phylogentically related to T'rematis. Formation and locality.—In the Trenton shales at Cannon Falls, Chatfield and Minneapolis, Minnesota. This species also occurs in the Trenton formation of New York and Kentucky; in the Utica formation at Utica, New York, and Ottawa, Canada; and in the Utica horizon at Cincinnati, Ohoi. Collectors,—W. H. Scofield, E. O. Ulrich and C. Schuchert. Bl2 THE PALEONTOLOGY OF MINNESOTA. [Gasteropegmata. Suborder GASTEROPEGMATA, Waagen. Family CRANIID, King. 5 Genus CRANIA, Retzius. 1781. Crania, Rerzius. Schriften der Berliner Gesellsch. Naturf. Freunden, vol. ii, p. 72. 1892. Crania, HALL. Paleontology of New York, vol. viii, pt. i, p. 145. Description: “Shell inequivalve, inarticulated, without perforation for a pedicle; subcircular in outline, generally somewhat transverse across the posterior margin; attached by the apex or the entire surface of the lower valve. Ventral or lower valve depressed-conical or conforming to the surface to which it is attached. Dorsal or upper valve more or less conical, with a subcentral, posteriorly-directed apex. External surface of the valves usually smooth, sometimes spinose or with concentric or radiating striz. In the interior of both valves are two pairs of large adductor scars, the posterior of which are close upon the margin and widely separated, the anterior near the center of the shell and close together, more approximate in the lower than in the upper valve. These posterior scars are often strongly elevated on a central callosity which surrounds their anterior margins. The margin of the lower valve is usually broad and thickened. Impressions of the pallial genital canals coarsely digitate. “Shell substance calcareous; strongly punctated by vertical canals which become subdivided toward the epidermal surface. “Type: Crania craniolaris Linné.” (Hall, op. cit.) : This genus had its origin in the Trenton formation and thence has existed through all geological time up to the present. One species is reported from the Chazy and another from the middle Primordial, neither of which have furnished undoubted evidence of their belonging to this genus. CRANIA SETIGERA Hall. PLATE XXIX, FIGS. 32 and 33. 1866. Crania setigera HALL. Description of new species of Crinoidea and other Fossils, p. 12. 1872. Crania setigera HALL. Twenty-fourth Rep. N. Y. State Cab. Nat. Hist., p. 220, pl. vil, fig. 15. 1892. Crania setigera HALL. Paleontology of New York, vol. viii, pt. i, pl. 1vH, figs. 14-16. Original description: “Shell small, suborbicular; length greater than width; cardinal margin nearly straight. Dorsal valve convex; beak elevated, pointed, situ- ated nearly one-third the length of the valve from the cardinal border. “Surface marked by comparatively coarse pustules or sete, which are more distant [distinct] near the margin of the shell.” The individuals of this species from the thin-bedded Trenton limestone have the surface pustules strongly elevated, appearing more like short spines. Those from BRACHIOPODA. 373 Crania granulosa.] the Trenton shales often attain a greater size, and have the sete usually less pro- nounced, while the beak is obtuse, the outline variable, and the cardinal margin only in rare instances straight. Free dorsal or upper valves are common, and but few specimens have been secured in which the valves conjoin, and are attached to an Orthis or Rafinesquina. These attached specimens are marked more or less with their host, causing the characteristic surface pustules to become obsolete, while the strie of those growing upon smooth surfaces have developed the sete. In specimens where these pustules have been removed by weathering or other causes, it is very difficult to decide whether they are individuals of C. setigera or C. trenton- ensis. Such specimens are usually referred to the latter species, but they commonly preserve a few pustules near the margin. A specimen of Monticulipora, with an individual of this species* attached, also has a parasitic species of bryozoan growing on it, which grew towards the Crania. Its growth, however, was limited towards the anterior portion of the Crania, leaving between it and the encroaching bryozoan a space 3-4 mm. in width. This limiting of the growth of the bryozoan may have been caused by the frequent extension of the arms of the Crania during life. Formation and locality.—In the Trenton limestone at Minneapolis; Trenton shales at Minneapolis, St. Paul, Cannon Falls, Fountain, Chatfield and Preston, Minnesota. Also from the Trenton at Decorah, Iowa; Mineral Point and Beloit, Wisconsin. In the Salmon River group or Loraine shales at Wilmington, Hlinois. Collectors.—C, L. Herrick, W. H. Scofield and the writers. Mus. Reg. Nos. 718, 5500, 7692-7696, 7958, Cranta GRANULOSA N. H. Winchell. PLATE XXIX, FIGS. 34 and 35. 1880. Crania granulosa N. H. WrNcHELL. Eighth Annual Rep. Geol. and Nat. Hist. Survey of Minnesota, p. 63. Original description: “Shell small, but prominently elevated at the beak; orbi- cular or somewhat widened between the antero-lateral margins: no concentric striz or undulations visible on the exterior of the shell, nor radiations; the whole surface of the dorsal valve uniformly fine-granulated or pustulose; these granulations not disposed in any apparent order. The lower valve unknown.” Crania scabiosa Hall, when growing on a bryozoan, usually has the upper valve strongly pitted. Specimens of this nature have received the name C. multipunctata Miller and Dyer. The outer surface of C. granulosa, however, is not pitted, but is crowded with small pustules irregularly arranged. Formation and locality—Trenton limestone at Minneapolis, Minnesota. Mus. Reg. No. 708. *This specimen is figured in Pal.-N. Y., vol. viii, pl. 1vH, fig. 14, 1892. 374 THE PALEONTOLOGY OF MINNESOTA {[Crania trentonensis. CRANIA TRENTONENSIS Hall. PLATE XXIX, FIGS. 36 and 37. 1866. Crania trentonensis HALL. Description of new species of Crinvidea and other Fossils, p. 12. 1872. Crania trentonensis HALL. Twenty-fourth Rep. N. Y. State Cab. Nat. Hist., p. 219. pl. vu, 1892. Crania trentonensis bss taster aes of New York, vol. viii, pt. i, pl. rvH, figs. 21, 22. Original description: “Shell medium size, strongly convex on the upper valve; width a little greater than the length, greatest width below the middle of the shell. Beak of dorsal valve small, pointed towards and situated near the cardinal border. “Surface marked by strong concentric lines of growth. No striz or radiating lines are visible. Transverse diameter eleven-twentieths of an inch; length half an inch.” This species differs from C. setigera Hall, in not having the upper or dorsal valve covered with elongate pustules. The shell of the dorsal valve of C. trentonensis is thick, and in this differs from C. scabiosa Hall, which is thin and usually partakes of the ornamentation of its host. Outline of the shell and position of the apex are variable features, and of little specific value among species of Crania. Formation and locality—In Minnesota this species has been found only in the Galena shales near Cannon Falls. One of the writers has found it in the ‘‘ Lower Blue beds” of the Trenton at Janesville, Wisconsin, and Dixon, Illinois. The type specimens are from the Trenton at Middleville, New York. Collectors.—W. H. Scofield and C. Schuchert. Mus. Reg. No. 7697. Genus CRANIELLA, @blert. 1888. Craniella, GAHLERT. Bull. dela Soc d’ Etudes Scientif. d’ Angers, p. 37. 1892. Craniella. HALL. Paleontology of New York, vol. viii, pt. i, p. 153. Description: “Shell somewhat irregular, outline subcircular or subquadrangular. Ventral valve thin, adhering by its entire surface; dorsal valve conoidal, more or less elevated; apex subcentral, posterior; interior of the dorsal valve without a well- defined border; impressions of the adductors large, very distinct, four in number, of which the posterior two are quite distant, the two subcentrals somewhat smaller, closely approximate or even confluent; from near each of the posterior impressions starts a vascular sinus, which is broad, strongly sinuous near its point of departure, narrowing gradually in following the contour of the valve, emitting from its mar- ginal side dichotomizing secondary branches, “Type: Craniella meduanensis @hlert.” (Hall’s translation of the original diagnosis.) The known species of this genus are C. ulricht Hall of the Trenton, C. hamil- tonie Hall of the Hamilton, and C. meduanensis blert of the Devonian of France. BRACHIOPODA. 375 Craniella ulrichi.] CRANIELLA? uLRicHt Hall. PLATE XXIX, FIGS. 38 and 39. 1892, July. Craniella ulrichi HALL. Paleontology of New York, vol. viii, pt. i, pp. 153, 181, pl. 1vH, figs. 1, 2. Compare Crania halli SARDESON,* Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p: 328, pl. rv, figs. 8-10; April, 1892. Description: “Shell moderately large. Outline normally circular. Apices sub- central, slightly posterior, inclined backwards. Upper valve with the posterior scars large and the adjustors well defined; anterior scars subdivided, the outer or posterior portion possibly representing the insertion of the brachial muscles. The vascular sinuses make a 3-shaped curve on the lateral portion of the valve, with the crest of the double arch towards the center; narrowing rapidly, becoming indistinct over the anterior region. Lower valve regularly curved, evidently unattached at maturity. Anterior adductors very large, situated on a thickened posterior area. Posterior adductor and adjustor scars very faint, lying just within the margin. The vascular sinuses are a series of low grooves extending forward in subparallel lines from the anterior and lateral margins of the central muscular area. External surface of the valves smooth or covered with concentric sublamellose growth-lines. Length of an upper valve, 16 mm.” (Hall, op. cit.) The specimens which can be referred to this species are free, separated, strongly convex valves, and are usually overgrown by bryozoans. Associated with them are numerous dorsal valves of Crania setigera Hall, also usually occurring as free valves. These can be separated from Craniella ? ulrichi, when the interior is not shown, only by their outer spinose surface. The material of C. ulrichi examined by Prof. Hall is identical with that which we have. All of the attached specimens on which he bases the statement, (p. 153) “is sometimes attached,” have proved to be Crania setigera. Among the many specimens of Crania and Craniella observed in Minnesota, not a single attached ventral valve with the dorsal valve removed has been found. When the ventral valve is present it is attached to some other brachiopod and has the dorsal valve covering it. Such specimens have invariably proved to be Crania setigera. That we have both valves among the large and free specimens of Craniella? ulrichi is prob- able, since the muscular scars and vascular markings are quite different in the two type specimens described and illustrated by professor Hall. This species is, there- fore, biconvex and probably attached by the apical portion of the ventral valve. Formation and locality.—Rare in the Trenton shales at Minneapolis, St. Paul and near Fountain, in the Galena shales, six miles south of Cannon Falls, Minnesota. Collectors.—E. O. Ulrich, W. H. Scofield and C. Schuchert. Mus. Reg. Nos. 7698-7700. *Mr. Sardeson’s name may really apply to this species, but neither his description nor figures are sufficiently diagnostic to enable us to determine this point satisfactorily. On the other hand, it would seem that his specimens must be distinct. because he had on several occasions been informed by one of us that Prof. Hall had named and described the present species in the work above cited. Asis well known, part tof that volume was printed nearly two years before it was published. 376 THE PALEONTOLOGY OF MINNESOTA. 5 [Pholidops. Genus PHOLIDOPS, Hall. 1859. Pholidops, HALL. Paleontology of New York, vol. iii, pp. 489, 490. 1892. Pholidops, HALL. Ibidem, vol. viii, pt. i, p. 155. Description: “Shells small, patelliform, equivalve, equiconvex, inarticulate, unattached. Outline oval or subelliptical; apex subcentral, excentric or marginal, sometimes terminal and produced. Surface marked by strong, concentric, often lamellose lines of growth, which are crowded on the posterior and distant on the anterior portion of the valves; these are sometimes crossed by faint, interrupted radiating lines. In the interior the surfaces of contact make a broad, smooth, flat or slightly convex border, somewhat broader in front than behind, The muscular and visceral area occupies a sharply-defined and very limited space in the apical portion of each valve. In both it is of essentially the same size and subtriangular in outline, the apex of the triangle pointing forward and usually surrounded by a conspicuous callosity. “The ventral(?) valve bears two well-defined central adductors occupying the ’ same relative position as in Crania; these impressions are usually simple, but appear to be sometimes complicated by association with ill-defined scars of the anterior muscles. The posterior adductors or divaricators are situated at the basal angles of the muscular triangle and are distant from the posterior margin. The linear parietal scars are very strong, the posterior being more or less distinctly lobate, the anterior generally straight or rounding about the central adductors. In the opposite or dorsal(?) valve the scars have essentially the same arrangement; the anterior adductors, however, are separated by elongate median scars (anteriors) which traverse the elevated callosity surrounding the anterior margin of the area. The posterior scars are often more widely divergent than in the other valve. Shell substance cal- careous and impunctate(?).” (Hall, 1892, op. cit.) Type: Orbicula ? squamiformis Hall. PHOLIDOPS TRENTONENSIS Hall, var. MINOR, n. var. PLATE XXIX, FIG. 40. The original description of P. trentonensis Hall* is as follows: “Shell small, broadly oval, very depressed-convex. Apex situated near the cardinal extremity. Surface marked by strong, concentric, lamellose lines of growth.” The Minnesota specimens in outline, convexity of valves, position of the apex and the strong lamellose lines of growth, agree with these parts as described and illustrated in P. trentonensis Hall. They are, however, one-half, but more often less * Descript. of new species of Crinoidea and other Fossils, p. 14, 1866. Twenty-fourth Rep. N. Y. State Cab, Nat. Hist. p. 221, pl. vil. fig. 8, 1872. BRACHIOPODA. 3774 Arthropomata.] than one-half the size attained by this species as found at Middleville, New York, and since they are constantly smaller, the varietal name minor is here applied to them. The growth lines are conspicuous in some specimens, while in others they are nearly obsolete. The muscular markings are undefined, owing to the tenuity of the valves. Formation and locality.—Not uncommon near the base of the Galena shales at St. Paul; associated with Clitambonites, three miles south of Cannon Falls and at Kenyon, Minnesota. Also in the upper part of the Trenton shales at Chatfield. Collectors.—A. D. Meeds and C. Schuchert. Mus. Reg. No. 7279. ‘Subclass ARTHROPOMATA, Owen. Order PROTREMATA, Beecher. Family CLITAMBONITIDA, n. fam.* Genus CLITAMBONITES, Pander. 1830. Klitambonites, PANDER. Beitrage zur Geognosie des russischen Reiches, p. 70. 1892. Clitambonites, HALL. Paleontology of New York, vol. viii, pt. i, p. 233. Orthisina, @ORBIGNY (1847) and subsequent authors. Description: “Shells with a subsemicircular marginal outline; convex or sub- pyramidal in the typical group. Hinge-line straight and forming the greatest diameter of the shell. Pedicle [ventral] valve elevated, cardinal area high, vertical, or sometimes incurved and crossed by a broad delthyrium, which is normally covered bya convex, perforate deltidium. On the interior of the valve the dental lamelle are very strongly developed, converging and uniting in the median line before reaching the bottom of the valve, thus forming a spondylium, which with the del- tidium encloses a conical subrostral vault. This plate is supported by a median septum extending for about one-half the length of the valve. [Adductor, diductor and adjustor scars occupy the upper surface of the spondylium.] In the brachial [dorsal] valve the cardinal area is considerably developed and the delthyrium filled by a conspicuous callosity, against the inner side of which the simple orthoid cardinal process abuts. The dental sockets are large, the crural plates low and continuous with the edges of the delthyrial callosity. A thickened transverse area is formed in the umbonal region by the union of the inner portions of the crural plates with the cardinal process, and thence a broad median ridge is continued forward through the muscular area, which is sharply defined and quadripartite. External surface covered with radiating striz. «Shell substance impunctate. *This family will contain Protorthis, Hall, Clitambonites, Pander, Hemipronites, Pander, and Scenidium, Hall. Waagen (Pal. Indica, vol. i, p. 576, 1884,) proposed the sub-family Orthisinw for the genus Orthisina. D’Orbigny’s family Orthiside contains Strophomena, Orthis, and Orthisina=Clitambonites, genera now referred to three distinct families. 378 THE PALEONTOLOGY OF MINNESOTA. [Clitambonites diversa. “Type: Pronites adscendens Pander.” (Hall, op. cit.) In well-preserved specimens of C. diversa the upper surface of the spondylium is transversely striated, these striz having three distinct curvatures in passing over it. Since their position and the area occupied agree with the muscular scars of this valve in Orthis, they are here regarded as homologous with the adductors, diductors and adjustors of that genus. In Lingulelasma, Lingulops and the trimerellids the mus- cular scars are not found in front nor underneath, but on the “platform” of those genera. The platform, therefore, is homologous with the spondylium of Clitambon- ites and Pentamerus. In Pentamerus galeatus Dalman, of the Lower Helderberg group of New York,* the adductors and diductors occupy nearly the entire spondylium, while the adjustors were probably situated on narrow flanges of the walls of the delthyrium. The portion of the valve immediately beneath the spondylium, and occasionally the sides of the septum, are strongly marked by the genital sinuses. Since there is no space posterior to these markings for the attachment of the muscles, this clearly indicates that they were situated on the upper surface of the spondylium. CLITAMBONITES DIvERSA Shaler, sp. PLATE XXX, FIGS. 11—17. 1865. Orthisina diversa SHALER. Bulletin of the Museum of Comparative Zoology, no. 4, p. 67. 1866. Orthisina verneuili BILLINGS. Catalogue of the Silurian Fossils of Anticosti, pp. 438, 74. 1877. Hemipronites americanus WHITFIELD. Annual Report of the Geological Survey of Wisconsin, 72 1882. Hemipronites shee ay eaten Geology of Wisconsin, vol. iv, p. 248, pl. x, figs. 15-17. 1889. Streptorhynchus americanus MILLER. North American Geology and Paleontology, p. 378. 1892. Clitambonites americanus HALL. Paleontology of New York, vol. viii, p. 289, pl. xvA, figs. 1-8. Original description: “'Toothed [ventral] valve, usually pentagonal; socket-valve quadrate; hinge-line usually equal to the greatest width of the shell. Toothed valve very strongly projecting; depth about one-half the width; deepest point about the hight of hinge-line; umbo somewhat laterally compressed, usually rising high above the plane of the hinge-line, but very variable in this respect; umbo always laterally inclined indifferently towards either extremity of the hinge-line. Surface near the extremities of the hinge-line a little depressed and slightly recurved; area very large, nearly half as wide as long. Fissure from one-fourth to one third the width of the hinge-line; deltidium large, massive, rarely central, with distinct circular or oval foramen. Socket-valve with a broad and shallow mesial fold.” Shell of medium size; subquadrangular in outline; hinge-line straight, rarely shorter, and usually as long as, or slightly longer, than the greatest width of the shell; cardinal angles often mucronate; lateral margins straight or nearly so, sloping *Pal, New York, vol. iii, p. 257, pl. xLvi and xLvit, 1859. BRACHIOPODA. 379 Clitambonites diversa] more or less abruptly into the broadly-rounded and centrally somewhat sinuous, anterior edge. Surface marked with numerous, subangular, prominent, sometimes tubulose striz, increasing in number by interpolation and bifurcation; from seventy to eighty-eight in adult examples along the margin and crossed by crowded, delicate, concentric growth lines some of which imbricate near the outer margin. Ventral valve strongly and evenly convex, with the point of greatest elevation near the beak. Cardinal area very wide, broadly triangular, flat or elevated, and slightly convex, distinctly striated longitudinally and finely transversely; deltidium broadly triangular, strongly convex, with a large oval pedicle opening in the apical portion; anterior margin broadly excavated and, when perfect, completely occupied by the chilidium of the dorsal valve. On the interior the dental processes are not very large and are attached to the strong lamelle, which converge and join centrally before reaching the bottom of the valve, forming the spondylium, which is supported by a well-developed septum terminating in the anterior third of the valve. The upper surface of the spondylium has a narrow median depression, which is some- times faintly divided by a fine line; the lateral limits of this plate are also slightly depressed, and the whole is crossed by numerous transverse lines of growth. The lines have a constant curvature in the median depression, with another over the area on each side and are strongly reflexed along the edge of the delthyrium. These markings are believed to be due to the adductor, diductor and adjustor muscles, which were attached to the upper surface of the spondylium, as not the slightest trace of any scar can be seen on the under surface of this plate, nor on the valve immediately beneath it. Genital markings numerous, delicate, originating under- neath the spondylium, radiating towards the antero-lateral margins and surrounded by the vascular sinuses. Outside of the latter there is a smooth space, while the anterior margin of both valves is slightly marked by radiating lines. Dorsal valve slightly concavo-convex, or almost flat; point of greatest elevation at the apex, where a shallow, narrowly-expanding medial depression has its origin and extends to the anterior margin. Cardinal area conspicuous but not wide, cen- trally occupied by a broad, short and strongly elevated chilidium, Underneath the latter, and attached to it, is what may be termed a simple cardinal process. The muscles are not attached to the top of this process, as in species of Orthis, but to the striated thickening of the rostral cavity and slightly to the basal portion of the process, the whole being covered by the chilidium. Dental sockets prominent, situ- ated at the point of union of the cardinal area with the chilidium. The crural plates form the inner edges of these sockets, are much elevated and continuous with the deltidium. The rostral thickening extends forward as a broad, low septum to near the center of the valve, and on each side are two strongly excavated, separate pairs 380 THE PALEONTOLOGY OF MINNESOTA. [Clitambonites diversa. of adductor scars. The antero-lateral edges of these are drawn out into short ridges, probably the bases of the vascular trunks. Outside the muscular scars are a number of small tubercles, indicating the genital spaces. This widely-distributed species was first described by Shaler as Orthisina diversa. A year later Billings identified it as O. verneuili Kichwald, at the same time regard- Shaler’s species as synonymous with it. On the other hand, Shaler has since referred Orthisina verneuili Billings to his species, in which he is correct. On comparison with the Kuropean species, as illustrated by de Verneuil,* it is seen that the American species is wider along the hinge-line, the ventral area much less incurved and elevated, with finer strize and a narrow sinus in the dorsal valve. These dif- ferences are sufficient to distinguish the two species. Specimens. of Hemipronites americanus Whitfield have been collected at Oshkosh, Wisconsin, and are found to agree with O. diversa Shaler of the Hudson River group of Anticosti. Castelnau,** as early as 1843, however, described as Terebratala borealis a shell derived from the “magnesian limestone of Green bay, Wisconsin,” which may prove to be this species. The only illustration given is of a ventral valve, and this is not satisfactory for positive determination. These type specimens are probably in the collections of the Academy of Sciences at Paris, France. C. diversa must have been quite often the prey of other animals, probably gastro- pods, as valves of this species are found with a single, large circular hole in them, -such as are often seen in recent shells. Others have been partially crushed, gener- ally near the anterior margin. That such injury was received during life, but was occasionally not sufficient to kill the animal, is shown by the fact that in some shells the damage was repaired. Such specimens are irregular in growth, the place of injury being indicated by more or less of a depression and great irregularity of the strie. Formation and locality.—Very common in the yellow shales here designated as Clitambonites beds of the Galena shales. With this species many forms are introduced which extend upward, while a number of species of the Trenton shales below do not pass into the Clitambonites horizon. A single specimen has been found in the uppermost layer of the shales on St. Anthony hill, St. Paul. Common at many localities south of Cannon Falls, Kenyon and Warsaw, Goodhue county; Eyota, and near Fountain, Minnesota. In the Galena at Oshkosh, Wisconsin. In the Trenton group, Ottawa, Canada. Also in division I of the Anticosti group, Anticosti. Some fragments of what appear to be a new species have been found by Mr. Ulrich one mile south of Burgin, Kentucky, in the middle Trenton beds. ; Collectors.—Miss C. E. Seymour, W. H. Scofield, A. D. Meeds and the writers. Mus. Reg. Nos. 5308, 5586, 5847, 5853, 6765, 7951-7957. *Russia and the Ural Mts., vol. ii, pls. xt and x11. ** Essai sur le Systeme Silurien de Amérique Septentrionale, p. 40, pl. xrv, fig. 14. BRACHIOPODA. 381 Clitambonites diversa, var. altissima.] CLITAMBONITES DIVERSA, Var. ALTISSIMA, 2. Ud?r. PLATE XXX, FIGS, 18 and 19. 1892. Clitambonites americanus var. HALL. Paleontology of New York, vol. viii, pl. xvA, figs. 7,8. This variety is readily distinguished by the exceeding elevation of the cardinal area of the ventral valve. This feature is so striking that its recognition seems to be demanded. Formation and locality.—Several specimens of this variety have been found by Mr. W. H. Scofield associated with C. diversa in the Galena shales south of Cannon Falls, Minnesota. Genus SCENIDIUM, Hall. 1860. Skenidiwm, HALL. Thirteenth Report N. Y. State Cabinet of Natural History, p. 70. 1892. Scenidium, HALL. Paleontology of New York, vol. viii, pt. i, p. 241. Description: “Shell subpyramidal, somewhat semicircular, with or without median sinus and elevation. Area large, triangular, divided by a narrow fissure, which is sometimes closed at the summit by a concave deltidium [spondylium]. Valves articulating by teeth and sockets, which are often obscure or obsolete. Dorsal valve flat, or varying from depressed-convex to concave. Beak entire, or indented by the foramen; cardinal line straight and usually equalling the width of the shell; cardinal plates broad and well developed, marked by the imprints of the peduncular muscles, and produced in the middle in a pointed process; the cardinal process extends, as a median. septum, through the length of the shell, and may be simple or divided at its anterior extremity. Ventral valve elevated, subpyramidal; beak straight or slightly arched; muscular impressions undetermined. Exterior surface covered with radi- ating strive.” (Hall, 1892, op. cit.) Type: Orthis insignis Hall. The ancestral stock from which Scenidium was developed is very uncertain, though it seems to have had its origin in the Clitambonitide. The genus appears in the Trenton, but it is not until the Lower Helderberg formation is reached that the greatest development of its generic character is attained. It is also known in the Middle Devonian of Europe. SCENIDIUM ANTHONENSIS Sardeson. PLATE XXX, FIGS. 20—23. 1869. Skenidium halli SAFFORD. Geology of Tennessee, p. 287 (undefined). 1892. Skenidiwm anthonensis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 383, pl. Iv, fig. 7. 1892. Scenidium halli HALL. Paleontology of New York, vol. viii, pt. i, p. 242, pl. virA, figs. 33-39. In its external characters this little species is much like the young of Orthis tricenaria, but the concentric growth lines show it to be an adult form. The hinge- 382 THE PALEONTOLOGY OF MINNESOTA. (Pentameride. line is longer, and the cardinal area of the ventral valve is wider, as compared with that species, while a more conspicuous mesial sinus and fold are present in S. anthon- ensis. Further in the apical portion of the delthyrium there is a small spondylium, and in the dorsal valve the space between the crural plates is thickened by shell deposit and is medially divided by a sharp, but low, cardinal process, the whole being drawn out into a long, angular, medial septum. Formation and locality.—Rare in the Trenton limestone and shales at Minneapolis, St. Paul and near Cannon Falls, Minnesota. In the Trenton at Dixon, Illinois. Common in the ‘‘ Glade limestone” at Lebanon, Tennessee, Collectors.—E. O. Ulrich, W. H. Scofield and C. Schuchert. Mus. Reg. No. 8252. Family PENTAMERIDA, McCoy. Genus ANASTROPHIA, Hall. ANASTROPHIA ? HEMIPLICATA Hall, sp. PLATE XXX, FIGS. 29—31. 1847. Atrypa hemiplicata HALL. Paleontology of New York, vol. i, p. 144, pl. xxx1u, fig. 10. 1856. Atrypa hemiplicata BrILLINes. Canadian Naturalist and Geologist, vol. i, p. 208, figs. 20-23. 1859, Pentamerus hemiplicatus BrLLINes. Canadian Journal, vol. iv, p. 316. 1859. Pentamerus hemiplicatus HALL. Twelfth Report N. Y. State Cabinet ot Nabural TEEtory, p. 66 1863.- Camarella hemiplicata BILLINGS. Geology of Canada, p. 168, fig. 154. 1892. Camarella bernensis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 328, pl. Iv, figs. 4-6. Original description: “Subglobose, pentagonal, wider than long, thickness often equal to the length; cardinal line distinct, short, with (in some specimens) the appearance of a small area on the dorsal [ventral] valve; dorsal [ventral] valve depressed-convex, with an abrupt, broad, not deep sinus, which commences nearly half way from the beak to the base, the beak very small and closely incurved [with a small triangular delthyrium underneath]; ventral [dorsal] valve very convex, becoming gibbous with a broad mesial elevation, commencing one-third of the dis- tance from beak to base, more gibbous towards the beak; sinus marked by two or three strong plications, with three or four upon the mesial lobe, and two or three on each side, all of which reach from one third to one-half the distance from the base to the beak of the shell, leaving the upper half entirely free from these markings; entire surface ornamented by fine, concentric, filiform, subimbricating lines, which are more conspicuous towards the base of the shell and beautifully undulated in crossing the plications.” ; In Minnesota this species occurs not uncommonly near the base of the Galena and differs from New York examples in having the umbo of the dorsal valve more tumid and elevated beyond that of the ventral valve. The transverse diameter in the former is also shorter, while the individuals are commonly smaller than those from eastern localities. BRACHIOPODA. 383 Anastrophia (?) hemiplicata, var. rotunda. ] The generic position of Anastrophia? hemiplicata and A.? scofieldi is left open for the present until more is known of the interior of those Lower Silurian shells with a camarelloid exterior. Formation and locality.—Not uncommon in the upper part of the Galena shales eight to thirteen miles south of Cannon Falls; and more rarely at Weisebachs’ dam near Spring Valley, Fountain and Preston, Minnesota; Decorah, Iowa; Neenah, Wisconsin. In the Trenton at Middleville, Watertown and Turin, New York; Center county, Pennsylvania; Ottawa, Canada. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 8232 to 8236. ANASTROPHIA? HEMIPLICATA, Var. ROTUNDA, ”. var. PLATE XXX, FIGS. 32—35. This variety is distinguished in having the length and width nearly equal, the valves more convex and the plications somewhat more pronounced on the fold and sinus, and less numerous on the lateral portions of the shell, The figured specimen is strikingly distinct from typical A.? hemiplicata in its greater convexity. Younger specimens, however, are less pronounced in this respect, but are still distingished by their shorter transverse diameter. Formation and locality.—The specimen figured is from the middle portion of the Galena formation; other smaller individuals have been secured from near the base of the same formation associated with “A.? hemiplicta near Cannon Falls, Minnesota, and at Decorah, Iowa. Collectors.—W. H. Scofield and the writers. Mus. Reg. No. 8231. ANASTROPHIA? SCOFIELDI, 2. Sp. PLATE XXX, FIGS. 24—28. This species seems to be a local development of A.? hemiplicata, and differs from it in having attained a larger growth, in being rounder in outline and in having the valves less gibbous, while the smooth or non-plicated portion of the shell is com- paratively greater. The fold and sinus also are less marked features, while the number of plications, not only here but on the lateral parts of the shell as well, is greater, there being on the fold and on each side respectively five to seven and three to six in A. (?) scofieldi to three to seven and three to four in A.? hemiplicata. In the interior of the ventral valve there is a long, triangular and very narrow spondylium, supported by a septum, and in the dorsal valve are the long crural plates not unlike those in Anastrophia verneuili Hall.* When the shell is distorted so that the posterior margins gape, it is seen that the dorsal valve has a very distinct cardinal area, which is more conspicuous than that of the other valve. This feature reminds one of species of Stricklandinia. Formatior. and locality.—A cluster of thirty specimens was found by Mr. W. H. Scofield near the base of the Galena at a locality eight miles south of Cannon Falls, Minnesota. Mus. Reg. No. 8280. *Pal. N. Y., vol. iii, p. 260, pl. xuvu1, fig. 1. 384 THE PALEONTOLOGY OF MINNNSOTA. [Strophomenidewe Family STROPHOMENIDA, King. Genus STROPHOMENA, Rafinesque (de Blainville). 1820. Strophomena,-RAFINESQUE. Annales Gen. Sci. phys. Bruxelles, tom. v, p. 232. 1825. Strophomena, de BLAINVILLE. Manuel de Malacologie et Conchyliologie, vol. i, p. 513, pl. Lim, 1892. Strophomena, HALL. oe ane of New York, vol. viii, pt. i, p. 245. Description: “Shells transversely subsemicircular or semielliptical; greatest width along the hinge-line. Surface concavo-convex and covered with fine radi- ating strize, which are equal or alternate in size. The pedicle valve is slightly con- vex about the umbo, but becomes rapidly concave toward the middle, with the apex perforated, except in old age. The cardinal area is conspicuous and nearly vertical and the delthyrium closed by a convex plate or deltidium [which is internally much thickened medially]. The teeth are widely divergent and are supported by plates which are produced into elevated ridges nearly surrounding the muscular area. The latter is relatively short, subcircular in outline, deeply excavated and divided medially by a more or less distinctly defined longitudinal ridge which is often continued over the pallial region. [Upon each side of this ridge in the poster- ior half are situated the small, narrow adductor scars, and these are surrounded by the large diductors. It is probable that the adjustors are also present outside the latter, but so poorly defined as not to be recognizable. | “The brachial valve is concave at the umbo, becoming strongly convex with growth; it has a much narrower cardinal area and the chilidium is rudimentary or incomplete. Dental sockets deep and continued as narrow grooves or indentations across the cardinal area. The crural plates are extended laterally with a shght curve, but are not supported by septa; at their inner margins they unite to form a callosity, upon which rests the short, bilobed cardinal process, which scarcely extends beyond the hinge-line. The muscular surface of this process is cordate in outline and is placed at a low angle to the plane of the area. A low median ridge extends for- ward from the hinge-plate separating two large adductor scars, in front of which are two narrow elongate impressions. Vascular and ovarian markings frequently well defined. Shell substance fibrous, strongly punctate. “Type: Strophomena rugosa Rafinesque (de Blainville), 1825—Leptena planum- bona Hall, 1847.” (Hall, op. cit.) The well known species of Strophomena can be separated readily into two natural groups; (1) those in which the shell is concavo-convex, and (2) where the valves are biconvex. The interior features are very similar in the two sections and are not available for grouping. The external form of the valves, however, easily Group I.—Valves concavo-convex.] BRACHIOPODA. aA. 355 allows any of the species mentioned below being referred to either one of the groups. There are, besides these species, a few others, but they are not sufticiently understood by the writers for positive classification. Rnnnnnnnnnnnnn mw RRARRARRHK 1838. 1843. 1844, 1847. 1856. 1859. 1863. 1883. 1892. Group I.—Valves concavo-convex. . tncurvata Shepard, Trenton. . thalia Billings, Trenton. trentonensis, n. sp., Trenton. septata W. and S., Trenton. neglecta James, Hudson River. naglecta, var. acuta, n. var., Hudson River. vetusta James, Hudson River. rugosa Rafinesque (de Blainville), Hudson River. rugosa, var. subtenta Conrad, Hudson River. planoconvexa Hall, Hudson River. planodorsata W. and S., Hudson River. wisconsinensis Whitfield, Hudson River. trilobata Owen, Galena. . fluctuosa Billings, Hudson River. . nutans (James Ms.) Meek, Hudson River. . hecuba Billings, Hudson River. Group II.—Valves biconvex. . minor Walcott, Upper Pogonip. . scofieldi W. and S., Galena Shales. . billingsi, u. sp., Trenton and Galena. . emaciata W.and S., Galena. - halliana Miller, Lower Hudson River. . sinuata (James Ms.) Meek, Hudson River. . suleata de Verneuil, Hudson River. . eardinalis Whitfield, Hudson River. STROPHOMENA INCURVATA Shepard, sp. PLATE XXX, FIGS. 36—40, Producta incurvata SHEPARD. American Journal of Science, vol. xxxiv, p. 144, figs. 1, 2. Orthis incurvata CASTELNAU. Wssai sur le Syst?me Silurien de l’Amérique Septentrionale, p. 38. Strophomena convera OWEN. Geological Exploration of lowa, Wisconsin and Illinois, p. 70, pl. xvu, fig. 2. Leptena filitexta HALL. Paleontology of New York, vol. i, p. 111, pl. xxx1B, figs. 3a to 3f. Strophomena filitexta BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 203, figs. 1, 2. Strophomena filitexcta HALL. Twelfth Report N, Y. State Cabinet of Natural History, p. 70. Strophomena filitexta BILLINGS. Geology of Canada, p. 164, fig. 142. Streptorhynchus filitexta HALL. Second Annual Report New York State Geologist, pl. Xx x1x, figs 1-7; pl. xu, figs. 11-14 (not figs. 10 and 15=S. neglecta James) Strophomena jfilitexta HALL. Palxontology of New York, vol. viii, pt.i, p. 251, pl. rx, figs. 1-17; pl. 1xA, figs. 11-14. Original description: “The extent of the magnesian limestone in Wisconsin, Upper Illinois and Missouri struck me with surprise. I observed it, in addition to the country already noticed between Chicago and Ottawa, as the prevailing forma- tion about the northern extremity of Michigan, the islands about Michillimacinac, 25— 386 THE PALEONTOLOGY OF MINNESOTA. [Strophomen necurvata. the mouth of Green bay, as well as near Navarino [now Green Bay city,\ Wisconsin], at the head of the bay. In the last mentioned region it abounded in a species of Producta,-which I take to be undescribed and shall, therefore, denominate the incurvata. Specific character: Semi-circular; hinge nearly straight and the length of the shell; with fine longitudinal striw; flattish; edge crenated; shallow valve, concave, basal margin incurved; muscular impressions and hinge-process very dis- tinct. The space between the valves is very small in this species.” Shell moderately large, more or less strongly concavo-convex, semi-oval, wider than long, with the greatest breadth along the hinge-line; cardinal extremities acutely angular and deflected, lateral and anterior margins regularly rounded. Sur- face marked by numerous, fine, subequal, crowded and rounded, radiating strie, increasing by intercalation, with every second, third or fourth one more prominent. This alternation in the size of the striz is variable; it is nearly obsolete in some, while in others it is a prominent feature, the whole surface being crossed by numer- ous and crowded, very delicate, raised, concentric lines and a few stronger marks of growth. Sometimes there are some oblique wrinklings along the cardinal margin on each side of the beaks. Ventral valve slightly convex in the umbonal region, but otherwise more or less deeply concave; point of greatest elevation at the beak, which is minutely perforated © for the passage of the pedicle. Cardinal area variable in width and elevation, slightly retrorse in very gibbose specimens or strongly elevated in flattish speci- mens; deltidium conspicuous, broadly convex, as wide as, or wider, than long, broadly excavated anteriorly and entirely occupied by the chilidium. The teeth are divergent, not very prominent and attached to the much elevated outer margin of the large, strongly striated, suboval muscular area. In the center of the posterior half of this area there are two slender, short adductor scars, which are separated by a septum attaining its greatest development toward the anterior margin, upon each side of which are the large impressions of the diductors, and probably also of the adjustors. On either side of the muscular area there are numerous, elongated tubercles, arranged in more or less regular radiating series, the genitalia markings. Near the outer margin of the valve is a more or less strongly defined, concentric, irregular thickening, crossed in the anterior region by a number of short, irregular, vascular sinuses. The whole of the interior is minutely granulose. Dorsal valve flattened or slightly concave in the umbonal region, and more or less strongly convex laterally and anteriorly; sometimes there is a shallow, narrow sinus present, becoming obsolete before reaching the anterior margin. Cardinal area narrow, vertical, centrally occupied by a very broad but short convex chilidium. Dental sockets]conspicuous, rapidly narrowing and continued as grooves over the BRACHIOPODA. 387 Strophomena incurvata. ] cardinal area along each side of the chilidium, with the thin, erect, crural plates forming their inner walls. The space between the crural plates is slightly thickened and occupied by a short, strong, bilobed cardinal process. Its upper surface is trans- versely striated and has a shallow median depression along each lobe. The rostral thickening is continued forward but a short distance and converges to a low median ridge which separates the two large, shallow scars of the adductor muscles. In front of the latter are sometimes seen two, linear, slightly diverging ridges, probably the markings of the main trunks of the vascular system. Genital markings on each side of the muscular scars, consisting of series of tubercles of various sizes radially arranged. Surface near the periphery more or less distinctly marked by numerous, short, irregular, radiating stria, much the strongest in the medial region. The variations of this species are mainly those of convexity, thickness of shell and alternation of striz. In the “Lower Blue beds” of Wisconsin, where this species is abundant, the alternation of strie is a very persistent character and the valves are usually flatter than specimens from other regions. In the Trenton shales of Minnesota S. incurvata is also a common species, often preserving the delicate markings of the interior. The variation in convexity here attains its maximum, and while the striew likewise alternate in size, this feature is never so conspicuous as in Wisconsin. This species is usually known as S. filitexta Hall. It is thought that to this form Shepard applied the name S. incurvata nine years prior to that given by Prof. Hall. One of the writers, through Mr. John M. Clarke, has endeavored to find the types at Amherst College, but Prof. Emerson states that no specimens of it with Shepard’s label attached exist at present in that collection. While the original description and illustrations are not very satisfactory, yet sufficient is shown, combined with the locality, to warrant the conclusion that the above specimens were of this widely distributed species. Strophomena convera Owen, proposed three years earlier than Hall’s name, is undoubtedly a specimen of the same species, which was derived from the “Blue and Grey limestone of Wisconsin and Iowa.” Probably Owen subsequently regarded it as identical with some other form, for in a subsequent report (1852) no mention is made of it. This species is commonly stated to occur in the Hudson River group, but a com- parison of specimens from that horizon with those from the Trenton will show the interior of the dorsal valve of the former to be entirely different in its prominent vascular ridges, while the space beneath the cardinal area on each side of the teeth in the ventral valve is filled up by a deposit of shell matter. Since Mr. U. P. James has applied the name Strophomena neglecta to one variation of the species identified by Meek in 1873 as S. filitexta, it is advisable to refer to the specimens from the 3858 THE PALEONTOLOGY OF MINNESOTA. [Strophomena neglecta. Hudson River deposits under that name. The literature treating of S. neglecta is given below, for the convenience of those having occasion to study this species. Formation and locality—Somewhat rare in the Trenton limestone at Minneapolis and Fountain, Minnesota. Common in the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Fountain, Preston, near Caledonia and elsewhere in Minnesota; Decorah and McGregor, Iowa. One of the common snecies in the ‘Lower Blue beds” at Mineral Point, Beloit, Janesville and Green Bay city, Wisconsin. In the Trenton limestone at Dixon and Dunleith, Illinois; Auburn, Lincoln county, Missouri. In the Black River, and at the top of Birdseye limestone near High Bridge, Kentucky. Glade limestone at Lebanon and Lavergne, Tennessee. Trenton limestone at Middleville and elsewhere in New York; at Ottawa and county of Renfrew, Canada. Collectors.—C, L. Herrick, W. H. Scofield, E. O. Ulrich and the writers, Mus. Reg. Nos. 669, 2147, 3733, 3734, 6771, 67738, 6795, 8167-8178. STROPHOMENA NEGLECTA James, sp. 1873. Strophomena filitecta MEEK (non Hall). Paleontology of Ohio, vol, i, p. 83, pl. VI, figs. 5a to 5d. 21875. Strophomena filitexta Wuitr. U.S. Geological and Geographical Survey west of the 100th Meridian, vol. iv, p. 69, pl. rv, fig. 8. 1875. Hemipronites filitextus MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 43. 1881, Streptorhynchus neglecta JAMES. The Paleontologist, no 5, p. 41. 1883. Streptorhynchus filitextus (partim,) HALL. Second Annual Report New York State Geologist, pl. xuu, figs. 10 and 15 (not figs. 11-14); pl. xx xrx, figs. 1-7. 1892. Strophomena filitexta HALL. Paleontology of New York, vol. viii, pt.i, pl. rxA, figs. 10 and 15 (not figs. 11-14); pl. x1A, fig. 3. This species is not known to occur in Minnesota, and is restricted to the Hudson River group. For further remarks see S. incurvata Shepard. Formation and locality.—Oxford, Clarksville, Waynesville and elsewhere in southwestern Ohio. Richmond, Versailles and Weisburg, Indiana; Savannah, Illinois; ?Silver City, New Mexico. STROPHOMENA NEGLEOTA, Var. ACUTA, ”. VAP. PLATE XXXI1, FIGS. 6 and 7. Shell of moderate size, resupinate, concavo-convex, the postero-lateral angles mucronate and deflected. Hinge-line wider than any part of the shell in front of it; cardinal area in the ventral valve three to four times as wide as that of the dorsal valve and somewhat elevated beyond it; cardinal margins more or less strongly wrinkled, the elevations being directed medially at various angles. Outer margin semi-ovate, narrowly rounding anteriorly, more broadly laterally, and terminating on the cardinal line in more or less prominent extensions. Dorsal valve plano- convex medially and regularly convex laterally; convexity varying with age, strong- est in the larger specimens; point of greatest elevation about mid-length. Ventral valve convex from the beak to nearly mid-length, from here to the anterior margin, and laterally as well, strongly concave, with the postero-lateral portions somewhat deflected. Surface strizw distinctly alternating, from three to five smaller lines between the sharply elevated larger ones. The alternation of the striz most distinct in the posterior half. BRACHIOPODA. 389 Strophomena trentonensis.] This variety in general appears to be closely related to Strophomena wisconsinensis Whitfield,* but is readily distinguished in being less convex and in the very distinct alternation of the striew. That species is clearly related to S. rugosa Blainville, while S. neglecta, var. acuta belongs to the S. incurvata group of strophomenas. Strophomena vetusta James** is probably also closely related, but it is more evenly convex, never has a flat central disc in the dorsal valve, while the outline is subquadrate. Formation and locality.—Not rare in the upper portion of the Hudson River group at Spring Valley, Minnesota. Collectors.—E. O. Ulrich. W. H.-Scofield and: the writers. Mus. Reg. No. 5550. STROPHOMENA TRENTONENSIS, ”. Sp. PLATE XXX, FIG. 41. 1847. Leptcena subtenta (partim.) HALL. Paleontology of New York, vol. i, p. 115 1883. Streptorhynchus subtenta HALL. Second Annual Report, New York State Geologist, pl. Xx X1rx, 1892, Strophomena subtenta ret eetesteeee of New York, vol. viii, pt. i, p. 251, pl. rx, fig. 18. This species is closely related to S. rugosa var. subtenta. The valves are, however, thinner, the striz more delicate and the oblique wrinkling along the cardinal mar- gins a more constant feature than in that species. The interior characters of S. trentonensis are also less strongly developed than in S. rugosa. Whether from New York, Minnesota, Kentucky or Tennessee, they exhibit the same undefined internal markings when compared with the Hudson River group specimens of the latter species. It is deemed also advisable to indicate this line of development towards S. rugosa of the Hudson River group by separating the Trenton specimens on the above characters with the name S. trentonensis. Prof. Hall (op. cit., 1847) found among the drawings of Mr. Conrad the figure of a Strophomena with the name S. subtenta attached. The specimen from which this drawing was made Prof. Hall says “is from a western locality” of the upper portion of the Hudson River group of Ohio or Indiana. This form was again described and ' figured by Meek} as S, plicata. As the essential difference between this form and S. rugosa is only in the oblique wrinkling of the shell along the cardinal margins we do not consider it of greater importance than varietal. Formation and locality—Not common in the Trenton shales at several localities to the south of Cannon Falls, Minneapolis and Fountain, Minnesota. In the ‘‘Lower Blue beds” at Janesville and Beloit, Wisconsin. Near the top of the Trenton at Frankfort, Kentucky, and Nashville, Tennessee; Trenton Falls, New York. A few examples apparently of this species have also been found in the Galena shales in Goodhue county, Minnesota. Collectors.—C. L, Herrick, W. H. Scofield and the writers. Mus. Reg. Nos. 677, 8179, 8182, 8183. *Geol. Wis., vol. iv, p. 263, pl. xur, figs. 11-13; 1882. ** Cincinnati Quart. Jour. Sei. vol. i, p. 241; 1874. + Pal. Ohio, vol. i, p. 81, pl. vi, figs. 4a-4h. 390 THE PALEONTOLOGY OF MINNESOTA. [Strophomena septata. STROPHOMENA SEPTATA W. and S. PLATE XXX, FIGS. 1-3. 1892, April 1. Strophomena septata W. and 8. American Geologist, vol. ix, p. 285. This species appears to be a local development of S. trentonensis W. and S., and as far as external characters are concerned, no distinguishing features can be pointed out. Compared with S. rugosa, a still closer resemblance, both externally and internally is seen. However, when the interior is shown it can be separated readily from both by the strong mesial septum of the ventral valve. This originates between the diductor scars and continues to increase in strength to near the anterior margin, where it often coalesces with one or two of the vascular ridges. In S. trentonensis the thickening of the interior near the anterior margin of the ventral valve is obso- lete or entirely undeveloped, constituting another distinguishing feature between it and S. septata. The cardinal process of both species is also more elevated, while the rostral thickening upon which it rests is developed less strongly than in S. rugosa, these parts being much as in S. incurvata. SS. trentonensis and S. septata never attain the thickness of shell nor the abundance of individuals of S. rugosa. The septum of the ventral valve in S. septata will also distinguish it from 9. incurvata, in addition to its smaller size and comparatively greater width than length. Formation and locality.—Common in the upper third of the Trenton shales at St. Paul, Minneapolis and near Rochester, Minnesota. Collectors.—C. L. Herrick, E. O. Ulrich and the writers Mus. Reg. Nos. 345, 676, 4936, 6795, 6798. STROPHOMENA RUGOSA (Rafinesque Ms.) Blainville. PLATE XXXI, FIGS. 4 and 5. 1825. Strophomena rugosa (RAFINESQUE) BLAINVILLE. Malacologie et Conchyliologie, vol. i, p.513, pl. Lim, figs, 2, 2a. 1827. Strophomenes rugosa DEFRANCE, Dictionnaire des Sciences Naturelles, vol. i, p. 151 and atlas. 1847, Leptoeena planumbona HALL. Palxontology of New York, vol. i, p. 112, pl. xxXX1, figs, 4a to 4e. 1850. Strophomena rugosa KiNG, Permian Fossils, p. 103. 1862. Strophomena planumbona HALL. Geology of Wisconsin, vol. i, p. 54, fig. 7. 1873. Strophomena (Hemipronites) planwmbona MEEK. Paleontology of Ohio, vol. i, p. 79, pl. V1, figs. 3a-3h. : 1874. Streptorhynchus (Strophomena) elongata JAMES. Cincinnati Quarterly Journal of Science, vol. i, p. 240. 1875. Hemipronites planumbona MILLER. Ibidem, vol. ii, p. 45. 1877. Streptorhynchus planumbonus MILLER. American Paleozoic Fossils, p. 134. 1878. Streptorhynchus elongata MICKELBOROUGH and WETHERBY. Journal Cincinnati Society of Natural History, vol. i, p. 76. 1880. Strophomena planumbona WHITE. Second Annual Report, Indiana Bureau of Statistics and Geology, p. 483, pl. m1, figs. 13, 14. 1881. Strophomena planumbona WuitTE. Tenth Report, Indiana State Geologist, p. 115, pl. u, figs. 18, 14. 1883. Streptorhynchus planumbona HALL. Second Annual Report New York, State Geologist, pl. XXXIX, figs. 15-17; pl. xuu, figs. 8, 9. BRACHIOPODA. 391 Strophomena rugosa (Rafinesque Ms.)] 1887. Strophomena planumbona (partim) SHALER. Memoirs, Kentucky Geological Survey, p. 13, 1892. Strophomena rugosa ae tes of New York, vol. viii, pt. i, p. 247, figs. 13, 14. 1892. Strophomena planumbona or rugosa HALL. Ibidem, p. 251, pl. 1x, figs, 15-17; pl. x1A, figs. 8, 9. From the examination made by Prof. Hall (op. cit., 1892,) it appears that this widely-distributed species was never described- by Rafinesque. Undoubtedly the latter sent to Blainville or Defrance, or both, specimens of it, with the name Sfro- phomena rugosa attached. The species is now well known as S. planumbona Hall. Blainville, 1825, was the first to give a diagnosis of Strophomena (loc. cit.), using as the type “8. rugosa Rafinesque,” of which he gives two good figures. These have been reproduced by Prof. Hall (op. cit., 1892). In 1827 a description was given of this species in the “Dictionnaire des Sciences Naturelles” by “D. F.,” probably Defrance. King, 1850, (op. cit.) called attention to the fact that Strophomena rugosa (Rafinesque) Blainville and Leptena planumbona Hall are one and the same species. A similar conclusion was also reached by Meek in 1873 (op. cit., p. 78).. The follow- ing is the description of S. rugosa of Defrance, which is copied from Paleontology of New York, vol. viii, pt. i, p.247: “Strophoméne rugueuse; Strophomenes rugosa Rafin- esque. Coquille bombée en dessous, et dont la valve supérieure est un peu concave et chargée de petites stries rayonnantes. Largeur, un pouce. Fossile de l’Amérique septentrionale. On voit une figure d’une coquille de cette espéce dans l’atlas de ce dictionnaire, planche de fossiles. Des coquilles de ce genre, qu’on trouve a Dudley en Angleterre, ont de trés-grands rapports avec cette espéce; elles en different pourtant en ce que le bord ce celles d’Amérique se retrousse un peu en dessous, tandis que c’est le contraire pour celles d’Angleterre, dont le bord s’abaisse en dessous. On trouve a Vembouchure de la riviére des Alleghanys prés de Pittsborough (Amérique septentri- onale), dans un grés rougeatre, des empreintes de coquilles qui ont beaucoup de rap- ports avec cette espéce, mais qui sont plus aplaties.”’ “Shell of medium size, concavo-convex, semi-oval or more than semi-circular in outline; hinge line generally a little longer than the breadth of the valves at any point farther forward; lateral extremities, in most examples, somewhat less than rectangular, or sometimes rather acute, more or less compressed and deflected; lateral margins a little contracted posteriorly and rounding to the front, which forms a regular semi-circular curve. “Dorsal valve flat [or somewhat depressed] in the umbonal region, and rather strongly and evenly convex in the central and anterior regions, from which it rounds off abruptly to the front and lateral margins; beak very small or not distinct from the edge of the narrow or sublinear area, which is inclined nearly directly backward, but not incurved. Interior showing the cardinal process to be small, depressed, divided to its base into two diverging tooth-like parts, a little flattened [or concave and 392 THE PALEONTOLOGY OF MINNESOTA. (Strophomena rugosa (Rafinesque Ms). striated| on their posterior faces and directed very obliquely forward and outward; socket ridges short and oblique [but much thickened, and upon them are placed the linear and but slightly elevated crural plates]; mesial ridge low [in some specimens, usually strongly elevated and rounded], extending but a little distance forward, while the space between it and the socket ridge, on each side, is occupied by a moderately distinct muscular scar. [Vascular trunks and genital markings faintly indicated and similar to those in S. incurvata.| “Ventral valve broadly and rather deeply concave in the central and anterior regions, and slightly convex at the beak, which is very small, abruptly pointed, scarcely projecting beyond the edge of the area, and usually [always] minutely perforated; area moderately high, extending the whole length of the hinge, generally but little sloping laterally, flattened and inclined more or less backward, foramen [delthyrium]| closed by a prominent, rounded deltidium, that is transversely striated and rather broadly sinuous on its inner edge, for the reception of the [chilidium, which partially covers the posterior portion of the] cardinal process of the other valve. Interior showing hinge-teeth to be well developed, trigonal and striated on their posterior sides, while from their inner bases the dental laminz extend forward so as nearly to encircle the usual saucer-shaped depression for the [diductor and probably very small adjustor| muscular scars, which is sometimes [always more or less] divided by a small linear mesial ridge [upon each side of which are situated the narrow adductor scars]; cardinal margin prominent and sharp within, on each side of the hinge teeth; anterior and lateral regions more or less thickened within and roughened by the crossing of the vascular markings, which are scarcely visible on any part within this zone. “Surface of both valves ornamented by numerous fine, closely-crowded, radi- ating striz# that are often alternately a little larger and smaller or, on some parts, with several of the smaller ones between each two of the larger; the smaller being always shorter than the larger, or ending at various distances between the free mar- gins and the beaks without coalescing with those between which they are intercalated. Striz and furrows minutely crenulated by extremely small, very regular, closely- arranged, concentric lines, invisible without the aid of a magnifier; a few subimbri- cating marks of growth are likewise seen near the free margins.” (Meek, op. c7t.) The comparative length and width of the shell vary considerably in this species, the latter being in some cases eqyal to two-thirds, in other cases only about one- half of the former. The narrow specimens with the long hinge-line have received the name S. elongata James, but a large collection will show every gradation between this and S. planumbona or rugosa. Some specimens are nearly as long as wide and are often difficult to separate from S. nutans (James’ Cat.) Meek. The latter, however, in its typical condition, is very distinct and approaches S. fluctuosa Billings. BRACHIOPODA. 393 Strophomena rugosa, var. subtenta.] S. incurvata Shepard, of the Trenton, became S. neglecta James, of the Hudson River group. S. trentonensis likewise was changed into S. rugosa Blainville, and S. winchelli developed into S. nutans. In the Trenton formation of Minnesota S. septata, a local variation of S. trentonensis, is found, and in the Hudson River group of the Northwest, S. rugosa and S. wisconsinensis are representatives of the latter. Formation and locality—Common in the Hudson River group in Ohio, Indiana and Kentucky; Anticosti; Iron Ridge, Wisconsin, and Spring Vailey, Minnesota. At Graf, Iowa, and Iren Ridge, Wis- consin, a variety occurs in which the concentric growth lines are very conspicuous and farther apart than in S. rugosa, and this may prove, when more material is at hand, to be specifically distinct. Collector.—C. Schuchert. Mus. Reg. Nos. 8184, (? 8185, 8186). STROPHOMENA RUGOSA var. SUBTENTA (Conrad Ms.) Hall. 1841. Strophomena subtenta CONRAD. Fifth Annual Report, New York Survey, p. 37 (undefined). 1847. Leptena subtenta HALL. . Paleontology of New York, vol. i, p. 115, pl. XxX xIB, figs. 9-9b- 1862. Strophomena subtenta BILLINGS. Paleozoic Fossils, vol. i, p. 132, fig. 109 on p. 130. 1873. Strophomena (Hemipronites) plicata (JAMES) MEEK. Palwontology of Ohio, vol. i, p. 81, pl. v1, figs. 4a, 4b. Conrad’s specimens of Strophomena subtenta were found in the Hudson River group of the Ohio valley, and can be distinguished from S. rugosa Blainyille only by the oblique wrinkling of the shell along the cardinal margins. This character we do not regard as of greater value than varietal. For further remarks see Strophomena trentonensis. Formation and locality—Rare in the Hudson River group at Spring Valley, Minnesota. Other localities, as for Strophomena rugosa. STROPHOMENA PLANODORSATA W. and VS. PLATE XXXI, FIGS. 8—10, 1892, Aprill. Strophomena planodorsata W. and S. American Geologist, vol. ix, p. 286. Shell large, semicircular or subquadrate in outline, concavo-convex, wider than long, greatest width along the hinge-line, or immediately in front of it. Surface with fine, radiating striz, every second or third one somewhat stronger than those intermediate, crossed by exceedingly delicate, closely crowded concentric lines, and towards the anterior margin by a few larger subimbricating lines of growth. Dorsal valve flat or very slightly concave for more than half the length and breadth of the shell from the cardinal margin, thence sloping rapidly towards the lateral and anterior edges. Cardinal area linear, slightly reflexed and centrally occupied by an inconspicuous deltidium. Interior unknown. Ventral valve slightly concave, except near the lateral and anterior margins, where it is strongly bent. Cardinal area 5 mm. or more in width in adult examples, more or less elevated, but never very strongly so; deltidium depressed convex, 394 THE PALEONTOLOGY OF MINNESOTA. [Strophomena winchelli. about as wide as long and distinctly limited laterally by linear elevations, with a depression outside of the latter; internally much thickened; apical perforation or pedicle opening exceedingly minute. Teeth not large for a shell of the size of this species; unsupported. Muscular depression very large, subquadrate in outline, with a sharply elevated outer margin, which has its postero-lateral limits outside the hinge teeth; medially divided by a more or less prominent ridge, upon each side of which are the large, longitudinally striated, diductor scars, enclosing the small adductors situated centrally in the posterior half. Space underneath the cardinal area filled up with shell matter. Near the outer margin there is occasionally a slight elevation, which is crossed medially by a few, not very prominent, vascular ridges. Entire interior surface covered with more or less radially arranged, delicate, oblique granules, which become more pronounced immediately outside the muscular margin. The size, large flattened area of the dorsal valve, and the subquadrate form of the muscular area of the ventral valve, distinguish this species from all others having the structure of S. rugosa. Formation and locality.—Rare in the Hudson River group near Spring Valley and Wykoft, Minnesota; Iron Ridge, Wisconsin, and Wilmington, Illinois. The interior characters are described from specimens from the last named locality. Collectors,—E. O. Ulrich, C. Schuchert. Mus. Reg. No, 8191. STROPHOMENA WINCHELLI Hall. PLATE XXXI, FIG. 11. 1888. Streptorhynchus (Strophonella?) deltoidea HALL (not Leptena deltoidea, 1847). Second Annual Report, N.Y. State Geologist, pl. Xx XIX, figs. 10, 12-14 (not fig. 11= S. nutans.) = 1892. Strophomena winchelli HALL. Paleontology of New York, vol. viii, pt. i, p. 344, pl. 1x, figs. 10, 12-14; pl. xx, fig. 26. This species, though quite as large, differs from S. trentonensis in being more commonly longer than wide, and is probably the parent stock of the later appearing species S. nutans and S. fluctuosa. From these it is separated readily by its thinner, less convex shell, finer and more numerous striz, the central disc also being without corrugations and less depressed than in S. nutans. A large collection would probably show intermediate variations between S. trentonensis and S. winchelli, as are found to occur between S. rugosa and S. nutans of the Hudson River group. These transitional specimens are, however, rare and should therefore not be used to unite the species. If this were done, to be consistent, all the above mentioned forms, together with S. incurvata and S. neglecta should be referred to one common, widely distributed and variable species. Formation and locality.—Rare in the ‘‘ Lower Blue beds” at Janesville and Clifton, Wisconsin. In the Galena at Oshkosh, Wiscousin. It has not been observed in Minnesota. Collector.—C. Schuchert. Mus. Reg. Nos. 8180, 8226, BRACHIOPODA. 395 Strophomena trilobata.] zg STROPHOMENA TRILOBATA Owen, sp. PLATE XXXI, FIGS. 12 and 13. 1852. Leptena trilobata OWEN. Geological Survey of Wisconsin, Iowa and Minnesota, p. 584, : pl. 1, figs. 17, 18. 1877. Strophomena trilobata MILLER. American Paleozoic Fossils, p. 138. Original description: “This species was at first referred to the species deltoidea, but the form is so decidedly different in several respects that it seems to constitute a distinct species. Dorsal valve broadly trilobate, very gibbous in front and depressed towards the hinge-line; margin undulating, semioval; ventral valve concave; hinge- line extended; fine and equally radiating striew, partaking of the curvature of the surface of the shell. “The outline of this shell is much more undulating, shell more gibbous and broader, and more distinctly trilobate than the de/toidea. “Tt occurs in the shell-beds F. 3A, near the Agency, on the Turkey river, lowa.” Owen’s illustrations, and his statement that the shell is “very gibbous in front and depressed towards the hinge-line,” leaves very little doubt that S. trilobata is identical with a species occurring in the middle beds of the Galena in Minnesota. It is true that associated with these specimens are also very gibbous examples of Rafinesquina deltoidea. These, however, are never as flat on the central disc nor have they the nasute anterior margin of S. trilobata. To S. fluctuosa this species is closely related, but can be distinguished by the following features: The flat central disc is comparatively smaller, the shell anteriorly is twice as long and incurved, while in S. fluctuosa it is always flat, and the ventral cardinal area is strongly retrose. The interior characters and the corrugation of the flat central disc are, as far as can be determined, essentially as in S. fluctuosa. Formation and locality——The species is abundant in the middle beds of the Galena horizon, but since it usually occurs as natural casts it is not often gathered by collectors. It occurs at Kenyon and elsewhere in Goodhue county, Mantorville, Old Concord and near Rochester, Minnesota. Turkey river Iowa. Probably also in the Galena of Wisconsin. Collectors.—A. D. Meeds, W. H. Scofield, M. W. Harrington and N. H. Winchell. Mus. Reg. Nos. 208, 293, 369, 371, 391, 7253, 8189, 8190. STRoPHOMENA FLUCTUOSA Billings. PLATE XXXI, FIGS. 14-17. 1860. Strophomena fluctuosa BILLINes. Canadian Naturalist and Geologist, vol. v, p. 57, fig. 6 1862. Strophomena fluctuosa BILLINGS. Paleozoic Fossils, vol. i, p. 123, fig. 102.- 1863. Strophomena fluctuosa BILLINGS. Geology of Canada, p. 209, fig. 207. 1892. Strophomena fluctuosa HALL. Palxontology of N. Y., vol. viii, pt. i, p. 251, pl. x1A, figs. 4, 5. 396 THE PALEONTOLOGY OF MINNESOTA. [Strophomena fluctuosa. Original description: ‘Triangular or semioval, usually widest at the hinge-line and more or less narrowly rounded, pointed, trilobed or nasute in front. ‘Dorsal valve convex, the visceral disc being in general equal to one-third the superfices of the whole valve, nearly flat, the remainder abruptly curved down all around so that the lower half of the length of the shell is sometimes at right angles with the upper half. The cardinal angles more or less compressed and often a little reflected, usually forming angular or narrowly rounded ears. Ventral valve concave, the curvature corresponding to that of the dorsal valve. “Area of dorsal valve lying in the plane of the lateral margin, about one-third of a line high. Area of ventral valve forming a right angle with the marginal plane, in large specimens one line or a little more in hight at the beak, and gradually decreasing towards the extremities of the hinge-line. “Foramen of ventral valve triangular; the width at the base somewhat exceed- ing the hight, completely closed by a convex deltidium, the basal margin of which is rendered a little concave by the convex margin of the similar deltidium [chili- dium] which closes the foramen of the dorsal valve. “Surface with a set of fine, rounded, elevated, radiating striz, distant from each other usually about half a line, sometimes a little less, and occasionally one line. Between each two of these there are from two to ten much finer striae; the whole crossed by fine, crowded, concentric lines. In most of the specimens the whole of the upper half of the shell is covered with short undulating wrinkles, which sometimes have a concentric arrangement and often form concentric rows con- verging from the hinge-line towards the center of the shell, crossing each other. The specimens from the Trenton limestone are usually without these undula- tions, [probably S. winchelli], but in those from the Hudson River group this character is prominently exhibited.” Interior of both valves very much as in S. nutans (James) Meek, or S. rugosa Blainville. This species has been confounded with Rafinesquina deltoidea Conrad, sp., as figured by Prof. Hall (Pal. New York, vol. i). The types now in the American Museum of Natural History, in New York city, have been carefully examined by Prof. Hall, Mr. Clarke and one of the writers. After considerable difficulty, owing to the thinness of the shells and the limestone matrix, it was proved that R. deltoidea, when compared with S. fiuctuosa, has the convexity of its valves reversed and is, therefore, a species of Rafinesquina. . deltoidea must therefore be restricted to the specimens figured by Hall in 1847. Trenton shells from Canada and Wisconsin, devoid of the corrugated surface, and usually referred to this species, are removed from S. fluctuosa and R. deltoidea and used as the type of a new species, S. winchelli Hall (op. cit., pl. rx, figs. 10, 12-14). S. fluctuosa thus becomes a well marked BRACHIOPODA. 397 Strophomena billingsi.] species, restricted to the Hudson River group, and takes the place of S. nutans of the Ohio valley, in the deposits of this formation on Anticosti and in Min- nesota. Formation and locality.—Common in the Hudson River group at Spring Valley, Wykoff and near Granger,, Minnesota: Anticosti. Collectors.—E. O. Ulrich, W, H. Seofield and the writers. Also in the collection of Dr. C. H. Robbins, of Wykoff, Minnesota. Mus. Reg. Nos. 232, 430, 4077, 8187, 8188. STROPHOMENA BILLINGSI ”. Sp. Fig. 32. Billings’ original illustration of Strophomena recta. a, side view; b, ventral view: ce, portion of face enlarged. : 1862. Strophomena recta BILLINGS (non Conrad). Paleozoic Fossils, vol. i, p. 130, figs. 108a—108e, Original description: “Semielliptical, both valves nearly flat, hinge-line equal to, a little greater or a little less than, the width; sides somewhat straight for about half the length, and either parallel or slightly converging forwards; all of the front half of the shell uniformly rounded, sometimes only gently convex or somewhat straight in the middle of the front margin. Ventral valve slightly convex in the umbonal regon, and elsewhere flat or gently concave; beak scarcely distinct from the cardinal area, slightly depressed below the umbo; area of medium size, flat, extending the whole length of the shell, forming an obtuse angle of from 110° to 135° with the plane of the lateral margin; foramen triangular, width at the base greater than the hight, closed by a convex deltidium which does not quite reach the hinge- line, but has its lower margin concave. Dorsal valve uniformly very depressed convex or nearly flat, slightly concave at the cardinal angles and with a barely perceptible mesial depression along the middle, which commences very near the beak and extends one-third or one-half the length of the shell; beak very small and minutely elevated above the cardinal edge; area varying in size from less than one- half to nearly equal that of the ventral valve. ; “Surface with fine, rounded, slightly crenulated, radiating strize of different sizes, the smaller coming in by implantation at various distances from the beak. In some specimens the strie are more nearly of one uniform size than in others; at the front margin there are usually four of the larger and four or five of the smaller striz in the width of one line. When the surface is perfectly preserved it is seen to be 398 THE PALEONTOLOGY OF MINNESOTA. & {Strophomena scofieldi. beautifully cancellated by fine, apparently squamose’ strie, which are undulated slightly upward in passing over the ridges. There appear to be from ten to twelve concentric strize in the width of one line. “Width of largest specimen collected, one inch; length, nine lines; hight of ventral area, one line.” . Strophmena recta Conrad we regard as founded on young specimens of the same author’s Strophomena deflecta, which is no longer referred to Strophomena, but belongs to Prof. Hall’s subgenus Dinorthis of Orthis. Even if the above conclusion is not accepted the specimens of Billings cannot be retained under Conrad’s name, since they clearly belong to Strophomena, while Strophomena recta Conrad must be referred to Dinorthis. This leaves Billings’ species without a name and we propose therefore to designate it as above. S. billingsi belongs to our group IL of Strophomena and is related to S. scofieldi. The former differs in having a far less defined sinus and fold, finer radiating strize and the concentric growth lines more delicate and closely crowded. Formation and locality.—In the Galena shales at St. Paul, near Cannon Falls and Fountain, Min- nesota. In the upper beds of the Trenton limestone, Ottawa, Canada. Collectors.—W. H. Scofield and the writers. Mus. Reg. No. 8192. STROPHOMENA SCOFIELDI W. and S. PLATE XXXI, FIGS. 18—21. 1892, April 1. Strophomena scofieldi W.and S. American Gevlogist, vol. ix, p. 286. 1892, April 9. Streptorhynchus subsulcatum SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 335, pl. rv, fig. 39. Shell small, semicircular in outline, biconvex, with a more or less prominent fold and sinus towards the anterior margin: hinge-line a little shorter than the greatest width; area of ventral valve forming an angle of about 140° with the plane of the lateral margin, centrally occupied by a convex, perforated deltidium, which fits closely against the chilidium of the other valve. Surface marked by numerous, crowded, rounded, radiating striz, increasing in number by implantation, with from 110 to 120 along the outer margin in adult shells, crossed by delicate, crowded, concentric lines and a few larger growth marks. Dorsal valve not deep, evenly convex, or with a fold near the anterior margin. Cardinal area very narrow and slightly reflexed. Crural plates prominent, very oblique, coalescing medially; upon this thickening at its base originate two low ridges, which continue upward and outward into the small, low cardinal process, about half of which is covered by the chilidium. Immediately underneath the crural plates are two pairs of small adductor scars, separated by a low, rounded BRACHIOPODA. 399 Strophomena emaciata.] and short septum, which bifurcates anteriorly. Near the anterior margin of the posterior pair of scars two other ridges arise, making four in all, probably the main trunks of the vascular system. Very small genital spaces indicated outside the muscular scars and in front of the crural plates. Ventral valve somewhat deeper than the other, evenly convex, or with a broad, shallow sinus near the anterior margin. Hinge teeth prominent and joining the outer elevated margin of the short, suboval, muscular area. This is centrally divided by a low ridge, separating the two pairs of adductor and diductor scars. This species is of the type of S. sinuata (James) Meek.* S. scofieldi can readily be distinguished from the latter by its smaller size and greater number of striw, having about sixty. The profound fold and sinus, greater size, and less numerous strize of S. sulcata de Verneuil,} will distinguish it from S. scofield?. Another related species is S. cardinalis Whitfield.{ The more elevated cardinal area, very convex dorsal valve and greater width of the shell, distinguish this form from S. scofieldi. Formation and locality.—Rare near the base of the Galena shales at Minneapolis and St. Paul; common in association with Clitambonites diversa at several localities south of Cannon Falls, Minnesota. A single specimen of it has been collected near the top of the ‘‘ Lower Blue beds” north of Beloit, Wisconsin. Collectors.—W. H. Scofield and the writers. Mus, Reg. Nos. 8198-8195. STROPHOMENA EMACIATA W, and S, PLATE XXXI, FIGS. 22—24. 1892, April 1. Strophomena emaciata W.and S. American Geologist, vol ix, p. 287. Shell small, depressed, biconvex, semicircular in outline; hinge-line usually somewhat smaller than the greatest width of the valve. Surface marked by numerous angulated striz, increasing in number by interpolation, having from sixty to seventy-five of the large and small ones along the anterior margin. Ventral valve depressed-convex, subangulated medially, greatest point of eleva- tion about mid-length. Cardinal area narrow, less than 1 mm. in width, strongly elevated, with a very convex, apically-perforated deltidium, which is somewhat wider than long and excavated for the reception of the chilidium. Dorsal valve slightly convex, with or without a shallow sinus, having its origin near the beak and rapidly widening to the anterior margin, which is more or less sinuous, according to the depth of the medial depression. Cardinal area linear, with a short, broad chilidium partially covering the cardinal process. Interior unknown. This little species was at first regarded as the young of some form of Stropho- mena. There are two species'associated with it—S. scofieldi and S. trentonensis. If *Pal. Ohio, vol. i, p. 87, pl. v, figs. 5a—5f. +Ibidem, p. 85, pl. v, figs. 4a-4e. =tGeol. of Wisc., vol. iv, p. 261, pl.2xtt, figs. 9, 10. 400 THE PALEONTOLOGY OF MINNESOTA. (Rafinesquina immature examples of the latter of the same size as adult individvals of S. emaciata be examined, it will be seen that a greater number of less conspicuous strize are present, that the shell near the anterior margin is decidedly more convex, and that the umbo is not depressed as in S. emaciata, the last feature being more or less strongly developed in all the concavo-convex Strophomenas. The subcarination of the ventral valve of S. emaciata is also present in S. trentonensis, but in the former the shell is evenly convex from the cardinal line to the anterior margin, while in the latter it is concavo-convex. With these constant differences there is no ground for assuming that S. emaciata is the young of S. trentonensis. In S. scofieldt it is seen that the hinge line is somewhat shorter, that the valves are more convex, and that the fold and sinus are just the reverse of those in S. emaciata. Formation and locality.—Several specimens have been collected by Mr. W. H. Scofield near the base of the Galena in the Clitambonites beds south of Cannon Falls, Minnesota. RAFINESQUINA, Hall, 1892. Strophomena of most American authors. 1892. Rafinesquina, HALL. Paleontology of New York, vol. viii, pt. i, p. 280. Description: “Shells normally concavo-convex. Surface ornamented by radi- ating strie of alternating size, crossed and crenulated by finer concentric striz. Cardinal margins without denticulations. Interior of the pedicle valve with the muscular area not strongly limited; consisting of two broad, flabellate, diductor scars enclosing an elongate, more distinctly defined adductor. The faintness of the limitation of this area is in marked contrast to the sharply defined muscular area in the corresponding valve of Leptena. In the brachial valve the cardinal process is more closely sessile than in Leptwna, and there is frequently a linear callosity between the branches. The posterior adductor scars have the arborescent markings of Lep- tena rhomboidalis, and these impressions are the only ones well defined, the anterior scars being narrow and rarely retained with distinctness. From the anterior margin of the muscular area radiates a series of irregular furrows and nodose ridges, which are, to some extent, of vascular origin. “Type: Leptena alternata Conrad. Trenton and Hudson River groups.” Rafinesquina had its origin in the Calciferous and died out in the Clinton group. BRACHIOPODA. 401 Rafinesquina minnesotensis.] RaFinesquina minnEsoTENSIS N. H. Winchell. PLATE XXXI, FIGS. 25—29. 1844. Strophomena deltoidea OWEN (not CONRAD). Geological Exploration of Iowa, Wisconsin and Illinois, pl. xvi, fig. 8; pl. xvn, fig. 6. 1852. Leptceena deltoidea OWEN (not CONRAD). Geological Report of Wisconsin, Iowa and Min- nesota, p. 620, tab. 2B, fig. 10 (not the middle figure). 1862. Strophomena incrassata HALL (not 1847). Geology of Wisconsin, vol. i, p. 42, fig. 16. 1873. Leptena deltoidea N. H. WiNcHELL. First Annual Report of the Geological and Natural History Survey of Minnesota, p. 101; Ibidem, Fifth Report, p. 148; : Ibidem, Eighth Report, p. 62. 1881. Strophomena minnesotensis N. H. WINCHELL. Ibidem, Ninth Report, p. 120. 1883. Strophomena incrassata HALL (not 1847). Second Annual Report New York State Geologist, pl. XXXvIt, figs. 1-5. 1892. Rafinesquina incrassata HALL. Paleontology of New York, vol. viii, p. 281, pl. vim, figs 1-5. Compare Leptena incrassata HALL. Paleontology of New York, vol. i, p. 19, pl. Iv bis, figs. 2a-2d, 1847. Original: description: ‘Shell semioblong or semioval, with the cardinal angle about 90°, or less than 90°; diameter from six to nine lines transversely, and from four and a half to eight lines perpendicularly [Wisconsin specimens attain a greater size]; the receiving [ventral] valve convex, sometimes more suddenly deflected after passing the visceral area; entering [dorsal] valve gently concave, but reflexed more rapidly about the margin; the exterior of the convex [ventral] valve marked by fine, radiating striz, every third, fourth or fifth one being larger than the intervening ones; interior of the convex [ventral] valve, which is best known from its frequent casts, shows a large muscular impression much resembling that of S. alternata as figured by Meek in vol. i, Pal. Ohio, plate vir, fig. 3c, but somewhat bilobate in front and larger in proportion to the size of the valve; scars of adductor muscles closely approximate, small and in many casts of this valve undistinguishable; behind they are separated (on the casts) by a short mesial ridge, which between them becomes a narrow mesial furrow and then a deep furrow, terminating at the sinus between the outer larger scars; the outer larger scars [diductors] are radiately striated from the beak [at the base of the dental lamella small adjustors are occasionally indicated]; their margins are strongly marked (on the cast) along their posterior sides by dis- tinct grooves formed by the dental plates, which diverge at once from the foramen at an angle of 100-120°, running nearly straight to the outer margins of the muscular scar, when they curve slightly towards the front; the anterior and lateral margins of the general muscular impression are slightly marked on the casts; outside of the muscular scar is a shallow marginal impressed line which is most evident at the cardinal angles as it converges toward the beak; interior edge of the cardinal line is carinate from the teeth to the cardinal angles; the details of the markings in the apex of the beak are seen on the valve itself to consist of two short, distinct, diverging ridges extending not much beyond the hinge teeth [enclosing the adductor -26 402 THE PALEONTOLOGY OF MINNNSOTA. {Rafinesquina minnesotensis scars], between the anterior ends of which rises a short mesial ridge of about the same size and length, with faint linear ridges parallel with it on each side, which extend a little further forward than the mesial ridge. The mesial ridge first gives place to a flat, unmarked interval, when it again rises more conspicuously, but nar- rower and sharper, extending nearly to the sinus separating the lobes of the outer muscular scar. The cardinal area of the convex valve slopes from the hinge-line obliquely backward, instead of being in plane with the lateral edges, thus differing from S. alternata. From three to five short undulations of the shell transverse to to the cardinal line, are seen often between the umbo and the cardinal angles, the heavier ones being near the cardinal angles. The cardinal process is bifid and prominent, the two parts being short, smooth, dentate protuberances that stand prominently exposed about parallel with the plane of the cardinal area. “The interior of the entering [dorsal] valve is very different from that of the entering valve of S. alternata. The general visceral disc is nearly flat, surrounded by a suddenly Hexed margin, inside of which is a shallow impressed broad line, most evident round the front; inside the cardinal angles are a few scattered, radiately- interrupted, short ridges or elevations [genital markings], but these do not prevail along the side nor in front, the surface there being smooth or finely granulated instead; in the center of the valve are five smooth, abrupt, digitately-spreading ridges, the middle one of which is a little larger and longer than the others; these rise more abruptly at their anterior extremities than behind, but none of them reach the beak, or even the umbonal region, though the exterior pair of lateral ones are placed further back than the others, converging at an angle of about 70° [and often pass through the large pair of adductor scars]. Socket [crural] ridges very short and widely divergent; behind them are small, doubly-grooved sockets.” The beak of the ventral valve is often perforated by a minute, circular, pedicle opening. R. incrassata Hall* seems to be a closely allied species, of which a few examples from the typical locality have been examined, but they are too poor for detailed comparison. These specimens and Prof. Hall’s figures of the species are constant in size and always smaller than Ff. minnesotensis. Billings,+ however, found R. incrassata in the Chazy limestone at the Mingan islands, and in the Black River limestone at the Fourth Chute of the Bonnechére, Canada. Specimens from the latter locality agree precisely with those sent me from Tennessee by Prof. Safford.” Of the Ten- nessee specimens referred to by Billings, the writers possess a complete series, and find them to be identical with FR. minnesotensis Winchell. It is probable that R. minnesotensis is only a larger development of the eastern R. incrassata. * Leptceena incrassata Hall. Pal. N. Y., vol. i, p, 19, pl. 1v bis, figs, 2a-2d. +Canadian Nat. and Geol., vol. iv, p. 443, 1859. BRACHIOPODA. 403 Variety inquassa. Formation and locality.x— Very common in the upper portion of the Trenton limestone at Minneapolis, St. Paul, Cannon Falls and Fountain, Minnesota. Also abundant in the ‘‘ Lower Blue beds” at Janesville and Beloit, Wisconsin; Rockton, Illinois. Very rare in the Trenton shales at St. Paul and Cannon Falls, Minnesota; Decorah and McGregor, Iowa. Also at Dixon, Illinois, in the Trenton; in the Birdseye lime- stone at High Bridge, Kentucky, and in the “Glade limestone” at Lebanon, Tennessee. Collectors.—C, L. Herrick, H. V. Winchell, Wm. Howling, W. H. Scofield and the writers. Mus. Reg. Nos. 671, 673-675, 681, 685, 704, 705, 2192, 3521-3523, 3731, 5059, 5097, 5673, 7919, 8143-8148. Variety rvquassa Sardeson. PLATE XXXI, FIGS. 27, 28. 1892. Strophomena inquassa SARDESON. Bulletin of the Minnesota Academy of Natural Science, vol. iii, p. 334, pl. v, figs. 22-24. This name is applied to large convex shells with a wide ventral hinge area which otherwise strongly resemble R. alternata. In Minnesota specimens are rare. They occur in the upper third of the Trenton shales and continue upward into the Galena, passing into a very gibbose form, FR. deltoidea Conrad. In Wisconsin variety inquassa is quite abundant near the base of the “ Upper Buff limestone” and has been identified by Hall as Strophomena incrassata (op. cit., 1862). It is not always easy to distinguish between Fk. minnesotensis, var. inquassa, Rk. deltoidea and FR. alternata. This is particularly the case between var. inquassa and the latter species when the exterior alone is visible. The thickening of the shell, however, near the anterior margin on the interior of the dorsal valve in R. alternata is much stronger, while the four ridges of R. minnesotensis, var. inquassa, two on each side of the median septum, are reduced to two in the former species. The tendency in the progressive line of development from Ff. minnesotensis seems to be towards larger growth (var. inquassa) and greater convexity (/. deltoidea), while another series tends to flatter shells and maximum of size (/. alternata). Formation and locality.—Rare in the Trenton shales at Minneapolis, St. Paul and elsewhere in Minnesota. Common near the base of the ‘“‘ Upper Buff beds” at Mineral Point, Wisconsin, Mus. Reg. Nos, 8141. RAFINESQUINA DELTOIDEA Conrad, sp. PLATE XXXI, FIGS. 30 and 31. 1839. Strophomena deltoidea CONRAD. Third Annual Report of the New York Geological Survey, p. 64; Fifth Report, p. 37, 1841. : 1842. Strophomena deltoidea VANUXEM. Geology of New York; Report Third District, p, 46, fig. 2. 1842, Strophomena deltoidea Emmons. Ibidem, Report Second District, p. 389, fig, 2. 1842. Strophomena camerata CONRAD. Journal of the Academy of Natural Sciences of Philadelphia, vol. villi, p. 254, pl. xiv, fig. 5. 1847, Leptena camerata HALL. Paleontology of New York, vol. i, p. 106, pl. xxx1A, figs. 2a, 2b. 1847, Leptena deltoidea HALL. Ibidem, p. 106, pl. xx x1, figs. 3a-3e. 1863. Strophomena deltoidea BILLINGS. Geology of Canada, p. 163, fig. 141. 1883. Streptorhynchus (Strophonella) deltoidea HALL. Second Annuai Report N. Y. State Geologist, pl. x1u, figs. 1, 2, 4 (not fig. 3). 1892. Rajflnesquina deltoidea HALL. Paleontology of New York, vol. viii, pt. i, pl. oxA, figs. 1, 2, 4. 404 THE PALEONTOLOGY OF MINNESOTA. [Variety inquassa. Original description: “Shell deltoid, with numerous radiating strie and concentric rugose undulations, obsolete on the inferior half of the valves; inferior valve slightly convex above, gibbose, abruptly rounded and flattened at the base; striz small and crowded; one or two lines in the middle of the valve larger and more prominent than the others; angles of the cardinal line slightly prominent. Length, one inch. Locality, Trenton Falls.” This species is closely related to Rafinesquina alternata, and differs from it both in its greater convexity and in the corrugations of the central disc. The latter feature is never very well developed in Minnesota specimens, while the convexity may be very great as in camura, with all variations to those nearly flat. These depressed convex specimens, especially when the concentric corrugations are obso- lete, approach R. alternata so closely that it is difficult or impossible to separate them. Such forms are, however, rare. This same difficulty is also met with in New York specimens. Prof. Hall writes,* “it is certainly often very difficult to draw the line of distinction between this species [R. deltoidea| and L. alternata, and more particularly so between this and L. camerata.” R. deltoidea is associated with Strophomena trilobata, a species with about the same curvature and corrugations of the central disc. The latter can be readily distinguished by the reversed convexity of the valves, the upper, or strongly rounded valve being the dorsal, while in RF. deltoidea this is the ventral valve. The nasute anterior portion of the shell and the small, flat, or even slightly concave, central dise will also assist in separating S. trilobata from R. deltoidea. Formation and locality. —From the top of the Trenton shales at St. Paul.and Cannon Falls, Minne- sota, examples have been found which probably belong to this species. Near the middle of the Galena formation at Mantorville, it occurs commonly as casts and retains more or less of the shell at several localities in Goodhue county, and at Weisebach’s dam near Spring Valley; close to the top of the forma- tion near Hamilton, and in the lower portion of the Hudson River group.at Granger, Minnesota. In the Galena at Oshkosh, Wisconsin, and near the top of the hills at Dubuque, Iowa.- Prof. Whitfield gives it as occurring in the Trenton, Galena and ?Hudson River group of Wisconsin. In the Trenton of New York and Canada. Davidson} mentions it as occurring in the Caradoc or Bala period in England, Scotland and Ireland, also ‘at Paggart, in Esthonia, and at Reval; in Norway and elsewhere.” It is believed by the writers, however, that a direct comparison of the British examples referred to R. deltoidea will prove them to be different from American specimens in their muscular markings and crural plates. Collectors.—M. W. Harrington, W. H. Scofield and the writers. Mus. Reg. Nos. 174, 182, 204, 261, 387, 389, 394, 3395, 8157-8164. RaAFINESQUINA ALTERNATA (Conrad Ms.) Emmons. PLATE XXXI, FIGS. 32—31. 1838. Leptena alternata CONRAD. Second Annual Rep. N. Y. Geological Survey, p. 115 (undefined) 1838-41. Strophomena alternata CONRAD. Ibidem, Third Report, p. 63; Fourth Report, p. 201; Fifth Report, p. 37 (undefined). 1842, Strophomena alternata EMMONS. Geology of New York; Report Second District, p. 395, fig. 3. “Pal. N. Y.,-vol, i, p. 107. +Monograph of British Silurian Brachiopoda, p. 292. BRACHIOPODA. 405 Rafinesquina alternata.] 1843. Orthis huronensis CASTELNAU. LEssai sur le Syst?me Silurien de l’Amérique Septentrionale, p. 37, pl xiv, fig. 6. 1843. Orthis plana CASTELNAU (not PANDER). Ibidem, p. 38, pl. x1v, fig. 1. 1844. Strophomena angulata? OWEN. Geological Explorations in Iowa, Wisconsin and Illinois, pl. xvu1, figs. 1, 3. 1847. Leptena alternata HALL. Paleontology of New York, vol. i, pp. 102, 286, pl. xxxt, fig. 1; pl. xxxIA, fig. 1; pl. Lxxrx, fig. 2. 1856. Strophomena alternata BILLINGS. Canadian Naturalist and Geologist, vol, i, p. 204, figs. 3, 4. 1858. Leptena alternata ROGERS. Geology of Pennsylvania, vol. ii, pt. i, p. 818, fig. 600. 1860. Strophomena alternata BiLLInes. Canadian Naturalist and Geologist, vol. v, p. 51. 1862. Strophomena alternata BILLINGS. Paleozoic Fossils, vol. i, p. 117. 1863. Strophomena alternata BILLInes. Geology of Canada, p. 163, fig. 140. 1865. Strophomena anticostiensis SHALER. Bulletin of the Museum of Comparative Zoology, vol. i, p. 62. 1873. Strophomena alternata MKEK. Paleontology of Ohio, vol. i, p. 88, pl. vu, fig. 1. 1875. Strophomena alternata MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 51, 1880. Strephomena alternata Wuitrk. Second Annual Report of the Indiana Bureau of Statistics and Geology, p. 481, pl. I, figs. 6, 7. : 1881. Strophomena alternata WuitE. Tenth Report State Geologist of Indiana, p. 113, pl. 1, figs. 6, 7. 1883. Strophomena alternata HALL. Second Annual Report N. Y. State Geologist, pl. xxxvumu, figs. 6-11. 1887. Strophomena alternata SHALER. Fossil Brachiopoda of the Ohio Valley, p. 4, pls. 1, Im. 1892. Rafinesquina alternata HALL. Paleontology of New York, vol. viii, p. 281, pl. viru, figs. 6-11. Conrad did not define nor describe this species, but gave it the Ms. name Leptena or Strophomena alternata, under which it became known to the geologists of the New York survey. Emmons published a figure of it in 1842, but Prof. Hall, in 1847, was the first to describe it as Conrad’s species. In 1843, however, Castelnau described and illustrated the same species as Orthis huronensis, and were it not for the previously published figure of Emmons this name would have to be adopted. S. angulata Owen is probably a misprint for S. alternata, since the identification is queried, and his initial is not added to the name, as was Owen’s custom with all new species. The following detailed description is that of Meek, from which a few paragraphs relating to varieties have been omitted: “Shell attaining a large size, semioval, the breadth being nearly always greater than the length; hinge-line as long as the breadth of the valves at any point farther forward, or somewhat longer; lateral extremities rectangular, sometimes compressed and moderately deflected; lateral margins a little convex, or slightly sinuous posteriorly, and rounding forward to the front, which is semicircular in outline. “Dorsal valve flattened in the umbonal and cardinal regions, and gently or more or less strongly concave in the centra! and anterior portions, and curved upward around the anterior and lateral margins; beak small, but projecting slightly beyond the edge of the area, which is very narrow or sublinear, and directed nearly back- ward. Interior with cardinal process strong, directed obliquely forward, with its two divisions distinctly diverging, and flattened and longitudinally striated on their posterior faces; sockets for the reception of the teeth of the other valve rather well 406 THE PALEONTOLOGY OF MINNESOTA. [Rafinesquina alternata defined; socket [crural] ridges very small and uniting behind the cardinal process to form a deltidium; [adductor] muscular scars comparatively small, but deeply impressed near the cardinal process on each side of a small, short, mesial ridge, and nearly surrounded by a low obtuse ridge formed by a thickening of the adjacent internal surface of the valve; anterior and lateral margins more or less thickened and genic- ulated within (especially in adult shells), the thickened zone being transversely fur- rowed [by the vascular sinuses], and sometimes granular, while outside of it the imme- diate edge of the valve is suddenly flattened and minutely striated and granulated. “Ventral valve a little convex at the umbo, but generally much compressed over the whole visceral region in the adult (which includes the whole surface of the young and half-grown shell), but becoming more convex (sometimes strongly so) anteriorly, or antero-centrally and laterally, and thence more or less curved up to the anterior and lateral margins; area of moderate hight, flat and directed obliquely backward nearly at right angles to that of the other valve; beak very small, scarcely distinct from the margin of the area, and minutely perforated; foramen broadly - triangular and arched over above by the deltidium, which is very deeply sinuous on its inner edge, the sinus being nearly or quite closed by the dental process and del- tidium [chilidium] of the other valve. “Interior with cardinal margin somewhat carinate within; hinge teeth moder- ately prominent, remote and widely divergent; dental ridges obscure and extending obliquely outward and forward, but not produced or curving to surround a saucer- shaped cavity for the muscular scars: scars of the adductor muscles narrow, long and closely approximated, or almost in contact; those of the cardinal [diductor] muscles on each side very large, fan-shaped, but shallow, separated sometimes by a small ridge in advance of the adductor scars, and marked by radiating furrows and ridges, while the anterior and lateral regions are usually marked by strize and scat- tering granules. “Surface of both valves ornamented by numerous radiating striz, that increase in number, on the ventral valve, mainly by intercalation, and are usually arranged with one to six or eight smaller and shorter ones between each two larger and more prominent ones, the largest one of which often occupies the mesial line, while on the dorsal valve they more frequently increase by division and are generally of more uniform small size. On well preserved specimens all the radiating lines are crossed by numerous very minute, regular, closely arranged concentric stri, that are invis- ible without the aid of a magnifier; a few moderately distinct subimbricating marks are also seen near the free margins of adult shells.” A comparison of the interior of Trenton specimens with those from the Hudson River group shows that the latter have all the parts more strongly developed, owing, BRACHIOPODA. 407 Rafinesquina alternata, var. loxorhytis.] in great measure, to the larger size attained and the greater thickness of the shell. Still, these differences are so conspicuous that it may prove desirable to distinguish the Hudson River forms by a varietal name. According to Hall,* the large thick- shelled variety occurring at Cincinnati is known to collectors there as Leptena pon- derosa. This name is very appropriate and if a separation is to be made it should be used, unless the objection is made that it was not defined; still, if the species is ascribed to Hall, there could be no doubt as to what form is meant. In England and Ireland this shell is commonly repreesented in the Caradoc and Lower Llandovery by Orthis expansa Sowerby, which is abundantly illustrated by Davidson in his monographs. In the Trenton shales FR. alternata, when the exterior alone is shown, is not always easily distinguishable from large and not very convex individuals of R. minne- sotensis. Usually, however, the stronger convexity and smaller size of the latter form and the five internal ridges of the dorsal valve will serve to separate them. Formation and locality.—A few specimens have been found in the Trenton limestone at St. Charles and it also probakly occurs elsewhere in these beds in Minnesota. From the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Lanesboro and Preston, Minnesota; not rare at the base of the Galena in the shales at several localities south of Cannon Falls, and at Kenyon and Fountain. Near the top of the ‘‘ Lower Blue beds” at Mineral Point, and probably elsewhere in Wisconsin. It also occurs in the Trenton at Dunleith, Illinois; Kentucky; Tennessee; New York, and Canada. Very common in the Hudson River group in Ohio, Indiana, Kentucky, Tennessee, New York and Anticosti. Collectors.—C. L. Herrick, H. V. Winchell, W. H. Scofield and the writers. Mus. Reg. Nos. 181, 287, 3396, 4037, 5859, 6761, 8151-8154. RAFINESQUINA ALTERNATA, Var. LOxORHYTIS Meek. PLATE XXXI, FIGS. 35—37. 1873. Strophomena alternata, var. loxorhytis MEEK. Paleontology of Ohio, vol. i, p. 91. 1875. Strophomena alternata, var. loxorhytis MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 53. Original description: “Attains a larger size [than R. alternata], moderately con- vex antero-centrally, or rather depressed; much extended on the hinge-line, with lateral extremities acutely angular, flattened and scarcely deflected; area very nar- row; both valves marked near the cardinal margin, toward the lateral extremities, by six to eight distinct, very oblique wrinkles on each side.” The shells referred to this variety agree in all essential features, except that the convexity is somewhat greater than in the Ohio specimens. f. kingi Whitfieldt is a closely related species, also occurring in the upper portion of the Cincinnati group, but it can be distingushed at once from RP. alternata, var. loxorhytis by its fine and equal strie. *Pal. N. Y., vol. i, p. 104, pl. xxxt, figs. 1a, 1i, 1m, 1847. + British Silurian Brachiopoda, p. 312, pl. xtv. figs. 1—10. +Struphomena kingi, Geol. Wisc.. vol. iv, p. 261, pl. xu, figs. 15, 16. 408 THE PALEONTOLOGY OF MINNESOTA. (Triplecia. Formation and locality.—Common in the Hudson River group at, and two miles east of, Spring Valley, Minnesota. Rather rare in the middle and upper portion of the same formation in Ohio and Indiana. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Also in the collection of Dr. C. H. Robbins, Wykoff, Minnesota. Mus. Reg. Nos. 4098, 8155. Genus TRIPLECIA, Hall. 1858. Triplesia, HALL. Twelfth Report New York State Cabinet of Natural History, p. 44, figs. 1-3. 1892. Triplecia, HALL. Palwontology of New York, vol. viii, pt. i, p. 269. Description: “Shell trilobate, transverse, unequally biconvex. Hinge-line straight and quite short. Pedicle valve shallow, convex about the beak, but depressed anter- iorly by a broad and deep median sinus; cardinal area low, erect and well defined; delthyrium covered by a narrow convex for flat] plate, with a circular foramen at the apex. In the interior the teeth are well developed and supported by short dental lamellz longitudinally dividing the umbonal cavity near the apex. Muscular area small, comprising two lateral scars, separated by a longer central adductor impres- sion. The brachial valve is very convex and bears a strong median fold. The car- dinal area is very narrow and the beak closely incurved. In the interior is an erect cardinal process, which is deeply bifurcated, the distal extremity of each branch bearing a single deep groove. This process is supported on a subrostral callosity, which also bears two short spiniform crural points at its base. Shell substance fibrous, impunctate(?). Surface with obscure concentric growth lines, and fine radiating strize on the inner lamine; in rare instances there are radiating lines on the exterior. “Type: Atrypa extans Emmons.” (Hall, 1892, op. cit.) Plicated species of this genus are unusual, T'riplecia being characterized mainly by smooth forms. T. radiata Whitfield and the following new species are the only ones known in America. In Britain there is but one, Triplecia sporiferoides McCoy, sp., from the Upper Llandeilo and Caradoc, and another, 7. cava Barrande, sp., from Etage D, of Bohemia. One is unwilling at first to regard these plicated species as congeneric with the smooth forms, but upon examination it is seen that the generic characters common to the one section are also present in the other. They were derived from smooth forms, since all of the nepionic and early neologic growth is without a trace of plications, they being first introduced during the later neologic stages. Species of T'riplecia are known from the Calciferous to the Upper Silurian. BRACHIOPODA. 409 Triplecia ulrichi.] TRIPLECIA ULRICHI, ”. sp. Fig. 34. Triplecia ulrichi, n. sp. a and 8, slightly restored dorsal and profile views of an entire specimen; ¢ and d, two views of the cardinal region of a dorsal valve, x 2; e, cardinal region of the ventral valve, X 2, showing the area, apical perforation, and other features. Lower part of the Hudson River shales, Fillmore county, Minnesota. Collection of EK. O. Ulrich. T. ulrichi is distinguished from all other American forms of the genus, except T. radiata Whitfield, in having rounded, rather distinct, radiating strie, of which there are from thirteen to eighteen on each side of the fold and sinus, the median region having seven or eight, making in all from thirty-three to forty-four on each valve. The fold and sinus are well developed, but less than is usual with species of Triplecia, and the deltidium is flat,,never convex. All of the specimens seen are more or less compressed, but the form in general seems to be near that of 7’. nucleus* Hall. Interior characters as in T. extans; Emmons, sp., the type of Triplecia. The other American striated species of T’riplecia is T. radiatat Whitfield from the Calciferous horizon at Beekmantown, New York, differing from 7. ulrichi in being much smaller and less tumid. T°. spiriferoides** McCoy, sp., of the Caradoc sandstone of Wales, has a much longer cardinal line and a more sharply elevated fold of the dorsal valve. The condition of the specimens of T. ulrichi may lead collectors to regard them as species of Orthis near O. borealis or coarsley striated specimens of O. subequata, var. gibbosa, but the covered delthyrium of the ventral valve, or the tumid umbo of the dorsal valve, will distinguish them from all orthoids. The forked cardinal pro- cess is always broken in separated valves, appearing simple, but preparations from specimens with the valves in place show it to have two delicate branches. Formation and locality —Ten specimens were found by Mr. E. O. Ulrich in the Hudson River group at Wykoff and three miles north of Spring Valley, Minnesota. Genus LEPTAINA, Dalman. 1828. Leptceena, DALMAN. Kongl. Svenska Vet.-Acad. Handl., for ar 1827, pp. 94-96, 106, 107 pl. 1, figs. 1, 2. 1892. Lepteena, HALL. Paleontology of New York, vol. viii, pt. i, p. 276. In its relations this genus is nearest to Rufinesquina Hall, from which it differs in its greater transversity; more or less strongly corrugated and geniculated valves; internal strongly elevated ridges near the outer margin of the dorsal valve, in which *Pal. New York vol i, p. 138, pl. xxxm1, figs. 2a-2c; 1847. +See above report, p. 137, pl. xxx1I, figs. la. 1b: 1847. *Bull. American Mus. Nat. Hist., vol. ii, no. 2, p. 43, pl. vu, figs. 5-8; 1889. **See Pal. New York, vol. viii, pt. i, p. 271, pl. x1c, figs. 10, 11; 1892. 410 THE PALEONTOLOGY OF MINNESOTA. (Leptzwna charlotte. the muscular area is also more elevated, and in the short, deeply impressed muscular area of the ventral valve. The surface corrugations are also developed among species of Rafinesquina and Strophomena. In the former, however, this character is never strongly marked, while the quadrangular outline and internal features will readily indicate their generic affinities. Strophomena can be distinguished at once from Rafiesquina or Leptena by the reversal of the relative convexity of the valves. For a detailed diagnosis of this genus, and for the reasons for restricting Leptena, Strophomena, Rafinesquina and Plectambonites to the characters of their type species, see Pal. N. Y., vol. viii, pp. 245, 276, 281. Type: Leptena rugosa Dalman—Producta rugosa Hisinger—Conchites rhomboidalis Wilckens. The following American species are of this genus: . charlotte W.and S., Trenton Shales. . tenuistriata Sowerby, Trenton to Hudson River. . wnicostata Meek and Worthen, Hudson River. . rhomboidalis Wilckens, sp., Niagara to Waverly. . rhomboidalis, var. ventricosa Hall, Oriskany. Leptena incrassata Hall, of the Chazy (Pal. N. Y., vol. i, p. 19), and Strophomena nitens Billings of the Hudson River group (Pal. Fos., vol. i, p. 118) may also belong here. Seal os. Lepr@na CHARLOTTA W. and S. PLATE XXXII, FIGS. 1—5. 1892, April 1. Leptena charlotte W.and 8. American Geologist, vol. ix, p. 288. 1892, April9. Strophomena halli SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 334, pl. Iv, figs. 36-38. Shell small, transversely semioval, plano-convex, geniculate, with the sides slightly convex and converging to the broadly rounded front, or drawn out tongue- shaped; hinge-line as long as, or somewhat shorter, than the greatest width of the shell. Surface marked by fine, closely crowded, alternating striz, as in Rafinesquina alternata, crossed by exceedingly delicate concentric lines and over the central flat disc of each valve by more or less continuous zigzag undulations or wrinkles. Ventral valve depressed-convex over the greater portion of the shell and more or less suddenly bent downward or geniculated along the margin, especially anteri- orly. Cardinal area wide, broadly triangular, with a convex deltidium, wider than long, apically perforated by a rather large pedicle opening, posteriorly excavated and completely occupied by the chilidium of the other valve. Crenulated hinge teeth prominent and supported by short dental plates, which are attached to the elevated outer, margin of the small, transversely oval muscular area, Within this area, in the center of the mesial thickening, are placed the short and narrow adductors, surrounded by the large diductors, and outside these, at the base of the BRACHIOPODA. 411 Leptena unicostata.] dental plates, are the distinct scars of the small adjustors. Surface marked by deli- cate, crowded papuille, strongest in front of the muscular area, and in the thin shells by the wrinkling of the outer surface. Dorsal valve nearly flat, with the anterior margin more or less reflexed down- ward. Cardinal area narrow, about one-third that of the other valve, with a broad and strongly convex chilidium. Dental sockets deep; crural plates slender, very oblique and merging into the median thickening, upon which is situated the small, bilobed, cordate cardinal process; in front of this is a short, low septum separating the small adductor scars; in the central portion of the valve there are three other inconspicuous septa. Just inside the outer margin of the valve is situated a prom- inent, rounded ridge of the same nature as that in L. rhomboidalis. L. charlotte differs from any other American species of Leptena in its zigzag, concentric, surface corrugations and in other minor features, which can be more readily seen in the illustration than by written comparisons. Formation and locality.—This species, in a dwarfed condition, is first met with in the upper portion of the Trenton limestone, and is not uncommon in the upper part of the middle third of the Trenton shales in the Bryozoa layers at Minneapolis and St. Paul, Minnesota. Collectors.—H. O. Ulrich and the writers. Mus. Reg. No. 8142. Leprana unicostata Meek and Worthen, sp. PLATE XXXII, FIGS. 6—9. 1868. Strophomena unicostata MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 335 1882. Strophomena unicostata EEA isel ies Geology of Wisconsin, vol. iv, p. 262, pl. xu, fig. 14. Original description: “Shell transversely subsemicircular, the greatest breadth being on the hinge margin, which terminates in rather acutely angular extremities; lateral margins generally nearly straight, or more or less concave in outline and converging from the extremities of the hinge to the front, which is rounded, a little straightened or slightly sinuous in the middle; geniculation of both valves from the ventral side, very abrupt all around the anterior and lateral margins to near the extremities of the hinge. Ventral valve almost perfectly flat [or slightly convex for a short distance anterior to the beak] and without any traces of concentric wrinkling on the disc between the hinge and geniculated front and lateral margins [in large Minnesota specimens there is more or less concentric wrinkling present in both valves, strongest along the cardinal line on each side of the beak and nearly obsolete medially]; beak very small or scarcely distinct from the cardinal margin and show- ing the usual minute [pedicle] perforation; area narrow, but a little wider than that of the other valve, and slightly arched and provided with a rather wider triangular fissure, closed by the convex deltidium [chilidium] and the cardinal process of the 412 THE PALEONTOLOGY OF MINNESOTA. (Leptzena unicostata. other valve. Interior with the hinge teeth not prominent; rostral cavity with a pair of small depressions, in front of which are two elongate and well marked scars of the adductor muscles; surrounding these, with their lateral margins strongly elevated, are the large bilobed and striated diductor scars, which continue forward for two-thirds the length of the valve; surface outside the muscular area covered with strongly elevated, oblique and minutely perforated pustules, more or less radially arranged; space underneath the cardinal area, on each side of the teeth, filled up with shell matter which, towards the extremities, is reflexed and becomes obsolete on the lateral portions of the valve. “Dorsal valve with the dise or visceral region flattened and, like that of the other valve, without any traces of concentric undulations; deflected anterior and lateral margins conforming nearly to those of the other valve; beak nearly obsolete; area linear and provided with a marginal furrow for the reception of the edge of the other valve; cardinal process rather small, cordate or bilobed, with the [crenated] socket on each side for the reception of the teeth of the other valve well defined; interior with [a pair of medially divided adductor] muscular scars generally moder- ately distinct and separated by a small mesial ridge [which is nearly obsolete a little posterior to the mid-length, with a small, shallow scar on each side, the septum then again becomig prominent and continuing to the geniculated margin]; other parts of the visceral region occupied by rather crowded [oblique and rather large] granules. Surface of both valves ornamented by fine, crowded, radiating striz, which increase by intercalation and division, while one of those on the middle of the ventral valve is generally five or six times as large as the others, and really forms a dis- tinct rib.” Adult Minnesota specimens referred to this species have concentric corrugations on the central flat disc, the latter being more convex than in Illinois examples. Associated with the large shells are also numerous smaller ones, which are compar- atively narrower, more mucronate and without wrinkles. Since these specimens are immature, and certainly of the same species as the larger ones, there is no hesitation in extending the specific description of L. unicostata so as to contain the corrugated examples. From L. rhomboidalis, var. tenuistriata Sowerby, this species can be dis- tinguished only by the obsolete or inconspicuous wrinkling, the large mid-rib and, when the interior is shown, by the very large, bilobed, diductor scars of the ventral valve. In the upper portion of the Hudson River group of the Ohio valley L. rhomboi- dalis, var. tenuistriata is a very common form, but is replaced by L. wnicostata in the same formation in northern Illinois, Wisconsin, Iowa and Minnesota. The latter species, it seems, must be regarded as a branch of the line leading to L. BRACHIOPODA. 413 Plectambonites. ] rhomboidalis, which so persistently recurs with more or less numerical strength throughout all formations from the Trenton of New York to the base of the Lower Carboniferous. In Anticosti Strophomena nitens Billings* occurs, which, as far as external characters are concerned, appears to be identical with specimens from Wil- mington, Illinois, examined by one of the writers. The interiors of these show them to be a species of Leptena Dalman, and they are apparently closely related to L. unicostata. Formation and localityx—Abundant in the upper portion of the Hudson River group at Spring Valley, and rare in the lower portion of the same formation at Granger, Minnesota. Common at Graf, Iowa; Iron Ridge and Delafield, Wisconsin; Savannah and Wilmington, Illinois. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Also in the collection of Dr. C, H. Robbins, Wykoff, Minnesota. Mus. Reg. Nos. 275, 8138-8141. Genus PLECTAMBONITES, Pander. 1830. Plectambonites, PANDER. Beitriige zur Geognosie des russischen Reiches, p. 90, pl. 11, figs. 8, 16; pl. xxvim, fig. 19. Lepteena of authors, not DALMAN. 1892. Plectambonites, HALL. Paleontology of New York, vol. viii, pt. i, p. 295. Description: “Shells usually small, normally concavo-convex. Surface covered with very fine striz, often alternating in size. Hinge-line making the greatest width of the shell, the extremities often subauriculate. Cardinal area narrow in both valves, crenulated on the margins. On the pedicle valve there is a moderately broad del- thyrium partly closed by a convex plate, but mostly occupied by the cardinal process of the opposite valve. Apical foramen sometimes retained. Teeth prominent and supported by thickened plates, which are continued in broad outward curves for more than half the length of the valve, returning and uniting in the umbonal cavity, thus limiting two linguiform [diductor] muscular scars, enclosing a more or less clearly defined adductor impression. “In the brachial valve the dental sockets are deep and often appear to transect the cardinal area. The cardinal process is simple and erect, but by its coalescence with the short, prominent, crural plates the posterior face appears trilobate. The crural plates end abruptly as in Orthothetes, becoming thickened at about the middle of their length and giving origin to two low ridges or septa, which at first approach each other and thence continue forward with a slight divergence, thus forming the inner boundaries for two elongate [adductor] muscular scars, which are less sharply defined in their outer margins. The muscular area is rendered quadripartite by two short transverse or oblique posterior furrows. Vascular impressions radial, sometimes digitate. Shell substance fibrous, sparsely punctate. *Pal. Foss., vol. i, p. 118, fig. 97, 1862; Canadian Nat. and Geol., vol. v, p. 53, fig. 1, 1860. 414 THE PALEONTOLOGY OF MINNESOTA. [Plectambonites sericea “Type: Plectambonites planissima Pander. Lower Silurian of Russia.” (Hall, op. cit.,) The following American species are referred to this genus: Netty tty 1839. 1840. 1842. 1847. 1852. 1856. 1858. 1863. 1873. 1874. 1875. 1875. 1883. 1890. 1892. 1892. 1892. 1892. 1892. . (2?) decipiens Billings, sp., Calciferous. . (2?) sordida Billings, sp., Calciferous. . sericea Sowerby, sp., Trenton to Clinton. . gibbosa W. and S., Middle Galena. . plicatella Ulrich, sp., Hudson River. glabra Shaler, sp., Anticosti. . transversalis Wahlenberg, sp., Clinton and Niagara. . transversalis, var. alabamensis Foerste, Clinton. . transversalis, var. prolongata Foerste, Clinton. PLECTAMBONITES SERICEA Sowerby, sp. PLATE XXXII, FIGS. 10-12. Leptena sericea SOWERBY. Murchison’s Silurian System, pl]. xrx, figs. 1, 2. Strophomena sericea CONRAD. Third Annual Report, Geological Survey of New York, p. 201. Strophomena sericea EMMONS. Geology of New York; Report, Third District, p. 47. Leptena sericea HALL. Paleontology of New York, vol. i, pp. 110, 287, pl. xxx1B, fig. 2: < pl. LXxIx, fig. 3. Leptena sericea HALL. Ibidem, vol. ii, p. 59, pl. x x1, fig. 1. Leptcena sericea BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 41, fig. 2. Lepiena sericea ROGERS. Geology of Pennsylvania, vol. ii, pt. ii, p. 818, fig. 599. Lepteena sericea BILLINGS. Geology of Canada, p. 163, fig. 139. Lepteena sericea MEEK. Palxontology of Ohio, vol. i, p. 70, pl. Vv, fig. 3. Leptena aspera JAMES. Cincinnati Quarterly Journal of Science, vol. i, p. 151. Leptena sericea MILLER. Ibidem, vol. ii, p. 57. Leptcena sericea? WHITE. U.S. Geological and Geographical Survey west of the 100th Merid- jan, vol. iv, p. 70, pl. IV, fig. 7. Leptena sericea HALL. Second Annual Report, N. Y. State Geologist, pl. XLVI, figs. 25, 29. Leptcena sericea FOERSTE. Proceedings of the Boston Society of Natural History, vol. xxiv, p. 293. Plectambonites sericea HALL. Palxontology of New York, vol. viii, pt. i, pl. xv, figs. 25-29. Lepteena minnesotensis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 329, pl. Iv, figs 24, 25. Leptena precosis SARDESON. Ibidem, p. 329, pl. Iv, figs. 26-28. Leptena recedens SARDESON. Ibidem, fig. 330, pl. Iv, figs. 29-32. Leptceena saxea SARDESON. Ibidem, p. 330, pl. Iv, figs. 33-35 Description: “Shell small, transverse, semioval, approaching semicircular, con- cavo-convex; hinge-line equaling or more frequently a little longer than the breadth of the valves at any point farther forward; lateral extremities varying from some- what acutely angular to nearly or quite rectangular and not properly reflexed; anterior and lateral margins forming together nearly a regular semicircular curve. “Dorsal valve concave, its deepest concavity being near the middle; beak not distinct from the cardinal margin; area narrow or nearly linear, and ranging at right angles to the plane of the valves. Interior showing cardinal margin to be minutely [in Minnesota, lower Hudson River specimens, strongly] crenate towards the lateral extremities; cardinal process moderately prominent [smooth] and trifid [simple, the lateral divisions are portions of the incomplete chilidium or crural plates], the middle division being most prominent, with a deep pit at its inner base; BRACHIOPODA. 415 Plectambonites sericea. ] brachial process short, appressed and widely divergent; muscular impressions [adductors] generally obscurely defined, occupying an obcordate area and separated from each other by two subparallel, narrow ridges that sometimes coalesce near the base of the cardinal process [and are strongly elevated and broadly thickened anteri- orly] each impression usually nearly equally divided by a slender linear [sometimes thickened and much elevated], straight ridge; anterior and lateral regions more or less roughened by minute, granular, radiating strie. [These are the markings left by the vascular and genital organs, anterior to which, in the thick shells, there is a well developed ridge just inside the front margin.] “Ventral valve moderately convex, being nearly evenly, but gently, arched along the middle from the beak to the front, and thus following so nearly the curve of the other valve as to leave but a very thin visceral cavity within; beak very small, or scarcely, if at all, distinct from the cardinal margin; area twice to three times as high as that of the other valve, inclined backward or more or less nearly parallel to the plane of the valves; foramen arched over near the beak by a small deltidium, and [nearly] closed between this and the hinge margin by the prominent cardinal process [and chilidium] of the other valve. Interior showing hinge margin to be obscurely [sometimes prominently] marked by minute pits for the reception of the crenulations of that of the other valve; teeth small; [diductor] muscular impressions long, narrow, separated behind by a short, linear, mesial ridge [upon each side of which are slender, shallow depressions of the adductor muscles], and diverging and extending forward beyond the middle of the valve, with a moderately distinct dental ridge along the lat- eral margin of each; anterior and lateral regions granulo-striate.”” (Meek, op. cit.) Surface of both valves marked by numerous, very minute, closely arranged, equal, radiating strize, or with every fourth, fifth or sixth one a little larger or more prominent than those between. Plectambonites sericea varies considerably in size, convexity, outline and in the strength of its muscular markings. The largest specimens observed were collected in the lower portion of the Hudson River group near Granger, Minnesota, and one of these is 28 mm. in width. Similar large examples occur at Cincinnati, Ohio, and have received the name Leptena aspera James. The crenulations along the lateral margins of the hinge-line are a very marked character in specimens from the former ‘ locality, and the muscular scars of the ventral valve are often not as divergent as in others on the same slab. As a rule, shells from the Galena horizon are smaller than those from the Hudson River or Trenton formations, to which Mr. Sardeson has given the name P. minnesotensis. Specimens are usually abundant at most localities. P. sericea is one of the few species extending through the Lower Silurian, and is replaced in the Niagara by P. transversalis Wahlenberg. As stated in the 416 THE PALEONTOLOGY OF MINNESOTA. [Plectambonites gibbosa. discussion of Orthis testudinaria, there can be little advantage to the geologist or biologist in applying to the numerous local variations of P. sericea specific or vari- etal names. Formation and locality.—Common in the Trenton formation of New York, Canada, Pennsylvania, central Kentucky, Tennessee, and Dixon, Illinois. From the ‘‘Upper Buff beds” of the Trenton at Rockton, Illinois; Mineral Point, Dodgeville and elsewhere in Wisconsin. In the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Fountain and Preston, Minnesota; Decroah and McGregor, Iowa. Very abundant in the Galena at many localities in Goodhue and Fillmore counties, Minnesota; Neenah and Oshkosh, Wisconsin. In the Hudson River group at Spring Valley, Minnesota; Graf, Iowa; Iron Ridge, Wisconsin; Savannah and Wilmington, Illinois; Indiana; Ohio; Kentucky; Anticosti; and Silver City, New Mexico. Clinton group of New York. In the Llaadeilo, Caradoc and Llandovery formations of England. Also in the Lower Silurian of Scotland, Ireland, Russia, Esthonia, Bohemia, Norway and Spain. Collectors.—C. L. Herrick, W. H. Scofield, E. O. Ulrich and the writers. Also in Dr. C. H. Robbins’ collection. Mus. Reg. Nos. 193, 228, 793, 3494, 3525, 4054, 4084, 4088, 4090, 5854, 5855, 6747, 6795a, 7929-7939, 7947-7950 PLEcTAMBONITES GIBBOSA W. and S. PLATE, XXXII, FIGS. 18-17. 1892, April 1. Plectambonites gibbosa W. and S. American Geologist, vol. ix, p. 288. Shell small, semicircular in outline, strongly concavo-convex, wider than long, greatest width along the hinge-line. Surface very finely striate, with six or seven stronger lines on each valve, much as in P. transversalis. Ventral valve very gibbous and subcarinate medially, lateral slopes rapid and slightly concave; greatest elevation about mid-length. Cardinal area strongly ele- vated, slightly concave, somewhat wider than that of the dorsal valve; delthyrium about as wide as long, with a small deltidium in the posterior portion, and more or less occupied by the cardinal process and chilidium of the other valve. Teeth small, supported by strong dental lamelle, which join the outer, much elevated margin of the muscular area. Diductor muscle pits deep, short, strongly diverging and sepa- rated posteriorly by a small septum, on each side of which are slender depressions of the adductor scars. Interior otherwise smooth. Dorsal valve concave and closely following the curvature of the other valve. Cardinal area wide, flat, retrose; delthyrium with a large, simple cardinal process more or less covered by a chilidium, which is usually imperfect medially. Crural processes short and widely divergent. Adductor scars broadly triangular in outline, , lobate, with the outer margin strongly elevated. They are separated medially by a narrow, deep depression, which is interrupted near the anterior margin of the scars by a transverse thickening. Two sharply elevated ridges have their origin at the hinge-line on each side of the muscular area. These curve much laterally for a short distance and then converge, meeting medially quite close to the anterior : BRACHIOPODA. 417 Orthide .] margin, where they become obsolete. The depression between this ridge and the outer elevated margin of the muscular area is granulose, while the slope on the outer side of the former is quite abrupt. This small species of Plectambonites is quite distinct from all other American forms. The convexity of the shell, surface ornametation and the interior char- acters of the dorsal valve will distinguish it at once from P. sericea Sowerby and P. decipiens Billings. Its relationship is yather with the latter species, on account of the sharp elevation just inside the margin of the dorsal valve. P. gibbosa seems to be closely allied to P. quinquecostata McCoy,* but until more is known of the interior characters of the latter further comparisons are impossible. That species is found in the Caradoc and Llandovery of England; also in Scotland, Ireland and Russia. Formation and locality —Not uncommon in the Galena at several localities in Goodhue county; also at Mantorville and Old Concord, Minnesota. Collectors.—M. W. Harringtop, A. D. Meeds, W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 147, 423, 8165, 8166. Family ORTHIDA, Woodward. Genus ORTHIS, Dalman, emend Hall. 1828. Orthis, DALMAN. Kongl. Vet. Acad.-Hand., pp. 93, 96. 1892. Orthis, HALL. Palzeontology of New York, vol. viii, pt. i, p. 192. Description: “The distinguishing features of these shells are the plano-convex contour; the strong, sharp and comparatively few coste, rarely, if ever, bifurcating; the elevated and somewhat incurved cardinal area on the pedicle valve; the relatively slight development of the dental lamella, which do not extend the entire length of the umbonal cavity. The cardinal process on the brachial valve is af elongate, vertical plate, extending from the apex the whole length of the delthyrium, thus longitudinally dividing the deep deltidial cavity. It is usually simple, both on the outer edge and at its distal extremity. “In this group of orthids [ Orthis restricted], more frequently than elsewhere, we find a character rarely developed in any stage of growth, viz: the existence of a transverse apical plate in the delthyrium of the pedicle valve [the rudiments of a deltidium]. 5 ns The greatest development attained by this feature, in any of the numerous species of Orthis studied, is to be found in 0. tricenaria of the Trenton and Hudson River faunas; it has also been observed in 0. calligramma, var. davidsoni, although it does not appear in any of the figures of this species and its varieties given by Mr. Davidson, nor is any mention made of it in his descriptions. Its *Sil. Foss, Ireland, p. 33, pl. m1. fig. 8, 1846; and Davidson’s Mono. British Sil. Brach., p. 322, pl. xLvi, figs. 28-27. 27- 418 : THE PALEONTOLOGY OF MINNESOTA. LOrthis tricenaria. appearance in this genus, and especially in the typical species of the genus, is inter- esting, but it cannot be embraced in the diagnostic characters, since its presence appears to be largely of a specific value, and the degree of its development dependent upon the stage of growth. [For further remarks on this plate see Dinorthis.] “The muscular scar of the pedicle valve of O. calligramma is a subelliptical area scarcely longer than the cardinal face, faintly impressed, and its components rarely distinguishable. “The structure of the shell is comparatively fibrous and impunctate. Specimens of Orthis calligramma, var. davidsoni, from Gotland, show openings of oblique tubules on the external surface, always situated upon the keels of the cost. These are sparse and irregularly scattered, but of similar nature to those seen in the impunc- tate species O. subguadrata and the punctate species O. subequata, O. michelini, O. resupinata and their allies.” (Hall, op. cit.) ORTHIS TRICENARIA Conrad. PLATE XXXII, FIGS. 18—23. 1843. Orthis tricenaria CONRAD. Proceedings of the Academy of Natural Sciences of Philadelphia, - vol. i, p 333. 1843. Orthis disparilis CONRAD. Ibidem, p. 333. 1844, Orthis testudinaria? OWEN. Geological Explorations in Iowa, Wisconsin and Illinois, pl. xv, fig. 11. 1847. Orthis tricenaria HALL. Paleontology of New York, vol. i, p. 121, pl. xxxu, fig. 8. 1847. Orthis disparilis HALL. Ibidem, p. 119, pl. xxxn, fig. 4. 1859. Orthis disparilis BILLINGS. Canadian Naturalist and Geologist, vol. iv, p. 440, fig. 20. 1859. Orthis tricenaria SALTER. Canadian Organic Remains, dec. i, p. 39, pl. rx, figs. 1-4. 1862. Orthis tricenaria HALL. Geology of Wisconsin, vol. i, p. 42, figs. 8-11. 1862. Orthis disparilis HALL. Ibidem, p. 435. 1863. Orthis disparilis BILLINGS. Geology of Canada, p. 130, fig 60. 1863. Orths tricenaria BILLINGS. Ibidem, p. 167, fig. 151. 1875, Orthis plicatella? WHITE (not HALL). Report of the U. S. Geographical Survey west of the = 100th Meridian, p. 72, pl. Iv, tig. 10. 1283. Orthis tricenaria HALL. Second Annual Report, N. Y. State Geologist, pl. xxxv, figs. 1-5. 1884, Orthis tricenaria WALCOTT. Monograph of the U.S. Geol. Surv., vol. viii, p. 74, pl. x1, fig. 4. 1892. Orthis tricenaria HALL, Paleontology of New York, vol. viii, pt. i, pp. 191, 193, 221, 228, pl. v, figs. 9-12. 1892. Orthis disparilis HALL. Ibidem, pp. 191, 221, 228. Original description: “Semioval, with“about thirty prominent, very regular, rounded ribs; larger [ventral] valve ventricose; summit elevated; the dorsal margins subrectilinear, very oblique; lesser [dorsal] valve flat or slightly concave in the middle; cardinal area very wide; apex of the larger valve profoundly elevated above that of the opposite valve. Length, three-fourths of an inch.” Shell semicircular in outline; plano-convex; anterior margin somewhat deflected ventrally. Hinge-line equal to the greatest width of the shell, rarely shorter. Cardinal area well developed on each valve, widest in the ventral valve, striated longitudinally and transversely, and divided by a very narrow delthyrium, which is BRACHIOPODA. 419 Orthis tricenaria.] partially occupied by a dela Surface with thirty to thirty-six radiating, equal, but sometimes unequal, simple, subangular cost, with a linear elevation occupying the depressions, all crossed by exceedingly delicate concentric lines of growth. ‘Ventral valve strongly convex, subangular, with the greatest elevation on the umbo, Cardinal area very wide, more or less convex and elevated. Delthyrium in the apical third occupied by a flat, concave or convex deltidium, which extends as well defined linear ridges along the entire length of the walls of the pedicle opening. Hinge teeth strong, supported by well developed, excavated dental plates, which join the outer elevated margin of the rounded muscular area. Diductor muscles occupy the greater portion of the muscular area, the anterior margin of which is slightly thickened and unites with the two large, diverging vascular trunks. The adductor sears are two slender depressions situated between the diductors and sepa- rated by a central linear elevation, the whole being drawn out anteriorly into a very narrow and short septum. Genital markings close to each side of the muscular area. Exterior to these are numerous markings of the vascular system. Peripheral margins of valves marked by radiating, short and strongly elevated coste, each with a central furrow. Dorsal valve nearly flat, slightly elevated at the beak; from this the point of greatest elevation, the surface slopes gradually into the broad, scarcely perceptible, rarely well defined, median sinus. Cardinal area wide, flat, divided by a triangular delthyrium, as broad as long, and more or less covered by a convex chilidium, the anterior margin of which is concave. Deltidial cavity occupied by a thin, much elevated, smooth cardinal process. Crural plates broad, strongly projecting inter- iorly, their bases converging and joining a low, broadly rounded, median septum, which becomes obsolete at about the mid-length of the valve. On each side of this septunt are two pairs of adductor scars, the posterior pair well defined. Vascular sinuses numerous, occupying the entire postero-lateral surface of the interior. Orthis costalis Hall,* of the upper beds of the Chazy group of New York, is closely allied to O. tricenaria. Remains of the former, however, are always more or less exfoliated, and this condition makes it difficult to point out satisfactory differ- ences between the two. Specimens figured by Mr. Walcott, and identified as QO. tricenaria, occur in the upper beds of the Pogonip group (probably equivalent to the Chazy group of New York and Canada), but are smaller than this species usually is. Such specimens, howeyer, are also found near the top of the Trenton limestone at Minneapolis, Minn. After a careful examination of these specimens, the writers are unable to point out characters by which they can be separated from 0. tricenaria, This variety was doubtfully identified by Dr. White (op. cit.) as O. plicatella Hall; but his illustrations show it to be the species cited above. *Pal. Ohio, vol. ii, p. 78. 420 THE PALEONTOLOGY OF MINNESOTA. (Dinorthis. O. disparilis Conrad proves to be the young of 0. se) as has been suggested by Hall and Whitfield.* O. davidsoni de Verneuil,+ of the Silurian of America, England and Scotland, is another closely related species, but can be distinguished from 0. tricenaria by its more convex cardinal area and the strongly elevated subangular costa. The costv also have a few remote oblique perforations in the shell substance, a feature never seen in O. tricenaria. Formation and locality.—This widely-distributed and characteristic Trenton fossil is often smaller in size in the Northwest than in either the eastern or southern exposures of the horizon. It occurs com- monly as natural casts in the Trenton limestone at Minneapolis, St. Paul and Cannon Falls; but in the Trenton shales good shells are not rare at. Minneapolis, St. Paul, Cannon Falls, Fountain, near Lanesboro, Byota, Preston, and near Caledonia, Minnesota; also at Decorah and McGregor, Iowa. In Wisconsin it is very abundant, and is a characteristic fossil of the ‘‘ Lower Blue beds” at Beloit, Janesville and Mineral Point; at the last locality it was also collected in a siliceous condition near the base of the ‘Upper Buff beds.” It has also been collected by one of the writers in the Trenton formation at Dixon, Illinois; High Bridge and Curdsville, Kentucky; and Watertown, New York. Near Ottawa and Montreal, Canada: Min- gan islands; Eureka and White Pine districts, Nevada. In Goodhue county, Minnesota, this species is known to extend upwards for at least fifty feet in the Galena formation at several exposures south of Cannon Falls. Collectors.—Miss C. S. Seymour, C. L. Herrick, H. V. Winchell, J. C. Kassube, W. H. Scofield, E. O- Ulrich and the writers. - Mus. Reg. Nos. 372, 666, 668, 2191, 3509, 4034, 5057, 5091, 5130, 5150, 5582, 6802, 7795-7810, 7916. Subgenus DINORTHIS, Hall. 1892. Dinorthis, HALL. Paleontology of New York, vol. viii, pt. i, p. 195. 1892. Plesiomys, HALL. Ibidem, p. 196. Original description: “This group of shells, in its most characteristic examples, presents a reversal of the relative convexity of the valves as seen in Orthis calli- gramma. The pedicle valve, elevated at the umbo, becomes gradually depressed as growth advances, and in the mature condition is flat or gently concave over the pallial region. The brachial valve, on the other hand, is eminently convex. The surface is marked by strong [and fine], simple, rarely bifurcating costa, as in 0. calligramma. The cardinal area of the pedicle valve is well developed, but not greatly elevated. In the interior the dental lamella are prominently developed and are extended around a subquadrate muscular area, the strength of which apparently depends upon the age and thickness of the shell. The three pairs of impressions may often be distinguished; the elongate adductors occupying a central position and separated by a faint median ridge, the diductors forming large ante- lateral expansions enclosing the adductors; the adjustors lie outside and behind these [pedicle muscles not always discernible]. Occasionally, in Orthis pectinella, there is again seen the gradual closing of the delthyrium of the pedicle valve by an *Pal. New York, vol. i, p. 20, pl. Iv bis, fig. 4, 1847. + Bull. Soc. Geol. de France, sec. ser., vol. v, p. 341, pl. rv, fig. 9, 1848. BRACHIOPODA. 421 Dinorthis.] apical callosity, but it is never carried as far as in the forms mentioned in the group of Orthis callactis, and, so far as observed, its existence is confined to the species cited. In the brachial or more convex valve the area is narrower, the crural plates stronger than in the preceding groups [Orthis callactis and O. plicatella], and the cardinal process, instead of being a simple linear ridge lying in the bottom of the deltidial cavity, is an erect apophysis, broadened and frequently bilobed on its sum- mit and posterior face. “The shell structure, like that of Orthis callactis and O. plicatella, is compactly fibrous and, in all the species examined, impunctate. No evidence of tubulose plica- tions has been seen.” Type: Orthis pectinella Emmons. In establishing the subgenus Dinorthis Prof. Hall was justified in separating the species having a similar contour of the valves, as in O. pectinella, but differing in the far greater number of striz. At that time no form was known to connect the sub- genera Dinorthis and Plwsiomys, respectively typified by O. pectinella and O. subquad- rata. In the Lower Silurian of Minnesota, beginning with the lowest fossiliferous member of the Trenton limestone, the first species is O. deflecta. This has characters common to the strophomenoids, but is clearly referable to Dinorthis. From this species to 0. (D.) pectinella, the one occurring next higher in the series, in the Trenton shales, there is a wide departure in the surface striation. 0. deflecta has very fine strie, while in O. pectinella there are strong plications. From 0. pectinella we pass to the variety sweeney?, which is a local variation of it. Associated with the latter are specimens in which the strong plications begin to divide near the anterior margin. At the base of the Galena shales the strong, simple, plicated forms become rarer, while those with more numerous strie prevail. Upon reaching the strata containing Clitambonites diversa Shaler, provisionally known to the survey as Galena shales, the numerously striated form, here described as O. meedsi, is the only one found. Ascend- ing into the Galena formation for thirty or forty feet more we find O. meedsi still exhibiting a tendency to increase the number of its striz, and finally assuming char- acters (variety germana) which attain their greatest development in O. subquadrata of the Hudson River formation. The change from O. pectinella to O. subquadrata is thus completed. The cardinal process is linear and not much elevated in O. deflecta, and attains its greatest development in O. subquadrata and O. proavita of the Hudson River formation. The adjustor scars are conspicuous in O. deflecta, while in the other species here referred to Dinorthis they are much reduced in‘size. In Orthis (Dinorthis) deflecta no pedicle muscle exists, but always a more or less large deltidium. Orthis (Dalmanella) subequata has sometimes a short deltidium, the 422 THE PALEONTOLOGY OF MINNESOTA. : (Orthis (Dinorthis) deflecta. posterior end of which is drawn inwards, and is transversley striated. When this plate is absent, as is commonly the case, the apical portion of the delthyrium is. filled with shell matter which served for the attachment of the pedicle muscle. In Orthis tricenaria the apical plate is always strongly developed and may be flat, con- cave or convex, the latter condition not being common. A small deltidium is also present in Orthis (Dinorthis) pectinella. In all the species of Orthis observed when a pedicle muscle is present a deltidium is absent; but where this plate is developed the muscle is rudimentary. This evidence leads the writers to the conclusion that the pedicle muscle is attached to the bottom of the valve in the apex of the delthy- rium when the deltidium is wanting, but when it is developed the muscle is then more or less attached to the deltidium. Ortuis (DinorTHIS) DEFLECTA Conrad, sp. PLATE XXXII, FIGS. %4—320. 1843. Strophomena deflecta CONRAD. Proceedings of the Academy of Natural Sciences of Phila- delphia, vol. i, p. 332. 1843. Strophomena recta CONRAD. Ibidem, vol. i, p, 382. 1847. Leptcena deflecta HALL. Paleontology of New York, vol. i, p. 118, pl. xxx1B, fig. 6. 1847. Lentcena recta HALL. Ibidem, p. 113, pl. xxx1B, fig. 6. 1859. Strophomena deflecta HALL. Twelfth Report, N. Y. State Cabinet of Natural History, p. 70 1859. Strophomena recta HALL. Ibidem, p. 70. > 1877. Streptorhynchus rectus Mi~tLER. American Paleozoic Fossils, p. 134. 1889. Streptorhynchus deflectum MILLER. North American Geology and Palwontology, p. 378. 1892. Plasiomys deflecta HALL. Paleontology of New York, vol. viii, pp. 197, 222, pl. vA, figs. 28-34. 1892. Plesiomys recta HALL. Ibidem, pp. 197, 222. Original description: “Semioval, superior [ventral] valve slightly concave deflected at the angles, the other valve reflected; radii very closely arranged, prominent, subequal, minutely crenulated; inferior [dorsal] valve slightly depressed in the middle; cardinal area wide; superior margin of the concave valve rather elevated. Breadth, half an inch.” : Shell semioval or subquadrate in outline; concavo-convex or strophomenoid in form. Hinge-line two thirds, or as long as, the greatest transverse diameter of the shell; width of cardinal areas variable, in some specimens comparatively wide, widest in the ventral valve, and disposed at a right angle to each other; delthyrium of both valves broadly triangular and partly covered. by a convex deltidium. Sur- face marked by fine, equal, sharply rounded striz, which increase in number by interstitial addition and rarely by bifurcation. From 120 to 135 along the anterior margin of adult examples. Striz and intermediate depressions crossed by numerous, elevated, thread-like, concentric lines and a few well marked minor imbrications, the latter indicating periods of rest in shell growth. Ventral valve carinate medially in the posterior third, with the lateral and anterior portions concave; the latter part is the stronger and forms a broad and undefined mesial sinus; greatest elevation at the beak, Cardinal area flat, broadly BRACHIOPODA. 423 Strophomena incurvata. ] triangular in outline, nearly horizontal, compared with that of the other valve, and marked by a number of parallel lines of growth; delthyrium widely triangular, covered from less than one-half to more than two-thirds its length by a depressed- convex deltidium, which is broadly excavated along the anterior margin. Interior with well developed dental plates, which join the outer elevated margin of the short, more or less quadrate-lobate muscular depression. In the center of this depression are the small, elongate, centrally divided adductors; on the outside of these and occupying the greater portion of the muscular area, are the diductors. At the base of the dental lamellz are the variously defined adjustors. Immediately beneath the cardinal area, and originating on each side of the muscular depression, are numerous antero-laterally directed genital markings. Vascular sinuses indistinct. Interior surface of the valves along the anterior margin with radiating, centrally channeled strie occupying the depressions between those of the outer surface. Dorsal valve evenly convex medially, with a more or less reflexed or concave portion on each side and immediately in front of the cardinal line. A defined narrow depression has its origin at the apex, which is soon merged into the shallow, though sometimes deep, mesial depression. Cardinal area striated, comparatively wide for species of Orthis. Delthyrium broadly triangular and covered by a chilidium at the apex, which continues along the walls of the delthyrium as separated plates. Crural plates short, but prominent, originating at the inner ends of the walls of the delthy- rium. The entire rostral cavity is occupied by a subhemispheric deposit of shell matter, upon the posterior surface of which is situated an elongate, linear, crenulate cardinal process, the anterior portion terminating in a short, broadly rounded median septum. On each side of the latter are situated the depressions of the adductor muscles, the posterior pair being most conspicuous. This species has been regarded, until quite recently, as a true strophomenoid shell. The contour of the valves, elongate hinge-line and fine striz, combined with more or less large deltidia, are doubtless strophomenoid features; yet the cardinal and articulating processes and the muscular arrangements are decidedly orthoid characters. Since these features are regarded as of greater importance than the former, this species should be referred to the subgenus Dinorthis, In the line of devel- opment between 0. (D.) deflecta and O. (D.) pectinella some links are missing. In the second species there is still a small deltidium in the ventral valve, which has been reduced in the dorsal valve to linear ridges bounding the delthyrium. The cardinal process is larger, the strize have become plications and have a tendency towards multiplication, while the general form and muscular scars are essentially those of O. (D.) deflecta. For further modifications of O. (D.) pectinella, see O. (D.) meedsi and its variety germana, and O. (D.) subquadrata. 4 424 THE PALEONTOLOGY OF MINNESOTA. ; LOrthis (Dinorthis) pectinella. Orthis platys Billings,* from the Chazy. limestone at Montreal, Canada, appears to be a closely related species, but can be separated from O. (D.) deflecta by its convex and deeper ventral valve and more delicate striz. e Billings identified Strophomena recta Conrad in the Trenton limestone at Ottawa, Canada. His illustrations clearly show that he had specimens of a true Strophomena before him, but not the S. recta Conrad, which is here regarded as the young of 0. (D.) deflecta. For further remarks see Strophomena billingsi, n. sp. Strophomena recta Conrad can be seen readily to be an immature condition of O. (D.) deflecta, by observing the growth lines on mature individuals of the latter species. The original material of both forms was obtained at Mineral Point, Wis- consin, and specimens of both have been collected by the writers at that locality and elsewhere in that state, all from the same geological horizon, and it is evident that the former is the young of the latter. Formation and locality.x—This common species is widely distributed in the Northwest, and is every- where observed to hold an identical horizon. In Minnesota it is restricted to the Trenton limestone in beds known as the ‘‘upper building stone,” occurring as casts at Minneapolis and St. Paul, and as free shells at Cannon Falls and in Allen Hunt’s quarries near fountain. In Iowa near McGregor. In Wiscon- sin it is a characteristic fossil of the ‘‘Lower Blue beds” at Mineral Point, Beloit, Janesville, and Dixon, Illinois. In the ‘‘Glade limestone” of Central Tennessee a variety of this species is often met with at Lebanon, Murfreesboro and Lavergne. In Kentucky a specimen has been found near the top of the Birdseye limestone at High Bridge. Collectors.—H. V. Winchell, C. L. Herrick, E. O. Ulrich and the writers. Mus. Reg. Nos. 672, 682, 5060, 5092, 5095, 7790-7794, 7928. OrtHis (DinorTuis) PECTINELLA (Hmmons) Hall. PLATE XXXII, FIGS. 31—34. 1842. Orthis pectinella EMMONS. Geology of New York; Report, Second District, p. 394, fig. 2 (not defined). 1847. Orthis pectinella HALL, Paleontology of New York, vol. i, p. 123, pl. xx x11, fig. 10. 1847. Orthis pectinella, var. semiovalis HALL. Ibidem, p. 124, pl. xxxu, fig. 11. 1856. Orthis pectinella BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 205, fig. 5. 1858. Orthis pectinella RoGERS. Geology of Pennsylvania, vol. ii, p. 818, fig. 602. 1863. Orthis pectinella BILLINGS. Geology of Canada, p. 165, fig. 147. 1880. Orthis charlotte N. H. WiNcuELL. Highth Report, Geological and Natural History Survey of Minnesota, p. 67. 1883. Orthis pectinella HALL. Second Annual Report, N. Y. State Geologist, pl. xxxrv, figs. 39, 40, 1889. Orthis pectinella, var. semiovalis MILLER. North American Geology and Paleontology, p. 359. 1892. Dinorthis pectinella HALL. Paleontology of New York, vol. viii, pt.i, pp. 195, 222, 228, pl. v, figs. 27-33. Original description: “Suborbicular or obtusely semioval, wider than long in the proportion of about nine to twelve; cardinal line extended, equal to, or less than, the greatest width of the shell, slightly deflected at the extremities; area moderately large and well defined; shell resupinate, or the area and foramen being principally on the latter valve, or partially common to both; dorsal [ventral] valve *Oan, Nat. and Geol., vol. iy, p. 488, fig. 15. BRACHIOPODA. 495 Orthis (Dinorthis) pectinella.] ; subconvex near the beak, with flat sides and a broad depression along the center, which is distinct in front; ventral [dorsal] valve regularly convex, most prominent in the center; beak extending ofily to the cardinal line; surface marked with from twenty-two to thirty prominent, rounded radii, which are equal to the spaces between; radii simple, or bifid and trifid towards the margin, crossed by small [closely crowded] elevated concentric [growth] lines.” In the interior of the ventral valve the dental lamellz are well developed and unite with the outer elevated margin of the elongate-quadrate muscular area. Within this area, occupying the central portion, are the elongate adductors divided by a very faint median elevation. These scars are surrounded laterally and anteri- orily by the diductors, while the adjustors lie outside of the latter at the base of the dental lamella. Genital spaces faintly indicated on the lateral area, each side of the muscular depression. The apical third of the delthyrium has a convex deltidium. Surface of both valves near the anterior margin more or less strongly marked by plications, each centrally suleated and opposite the depressions of the outer surface. Interior of dorsal valve with a well defined, bilobed and striated cardinal process occupying the apical portion of the delthyrium; immediately underneath it is a a low, rounded and short median septum separating the adductor scars, which are rarely divisible into four impressions. Crural plates first form the walls of the delthyrium and then extend into the interior as strong projections. Orthis pectinella is very constant in its characters throughout its geographical distribution, and is restricted to the Trenton group. In Mercer county, Kentucky, the largest growth and number of individuals is obtained, while in Minnesota the tendency is towards dwarfing. The small size and neatness of the majority of indi- viduals of this species led one of the writers to regard them as a distinct form, to which the name 0. sweeneyi was applied. Recently, however, large specimens show- ing the interior have been discovered, and these prove to be O. pectinella. Since more than two-thirds of the individuals occurring in Minnesota are smaller than those-obtained elsewhere, it is considered advisable to retain the name 0. sweeneyt as a variety of the species. This new material has also shown that O. charlotte Winchell is founded upon an unusually convex ventral valve of O. pectinella. Formation and locality—Rare in the Trenton shales at St. Paul, Minneapolis and near Cannon Falls, Minnesota; Decorah, Iowa. Common in Mercer county, Kentucky; Middleville, Trenton Falls, Turin, Watertown and elsewhere in New York, Pennsylvania and eastern Canada. Collectors.—W. H. Scofield, C. L. Herrick, E. O. Ulrich and the writers, Mus. Reg. Nos. 667, 7767. 496 THE PALEONTOLOGY OF MINNESOTA. [Orthis (Dinorthis) pectinella, var. Sweeneyi. OrvrHis (DINORTHIS) PECTINELLA, Var. SWEENEYI Winchell. PLATE XXXII, FIGS. 35—38. 1881. Orthis sweeneyi N. H. WINCHELL. Ninth Report, Geological and Natural History Survey of Minnesota, p. 117. 1892. Dinorthis sweeneyi HALL. Paleontology of New York, vol. viii, pt. i, pp. 196, 222, 228, pl. v, figs. 34-36. Original description: ‘Shell suborbicular, with a straightening along the hinge- line, and having the general aspect of Orthis pectinella, but with a shorter hinge-line. “The receiving [dorsal] valve is convex, with flattened lateral marginal areas and cardinal angles; costz coarse and simple, numbering about twenty-two, all of which continue to the beak except two or three on each side, which in passing from the margin in front of the cardinal angles, rather terminate on the hinge-line. The costz and the furrows, which have about the same width, are crossed by fine, crowded, concentrie striz; beak distinct, but not much elevated above the margin of the area; area slightly arched, but directed in the plane of the edges of the valves; area [foramen] triangular, equilateral, containing a simple tooth which rises to the apex, but is not developed so as to appear in the plane of the cardinal area, but is horizontally ribbed on either side. “The entering [ventral] valve is flat, with a little elevation at the beak and umbo, and a broad, sight concavity between the umbonal region and the front margin; coste the same as on the convex valve; beak small and more abrupt than that of the other valve; area low and flat, but of nearly the same hight as that of the other valve, with which it forms an angle of about 45°; foramen partially closed, but open below, broadly triangular. “The transverse diameter is seven lines in the single specimen belonging to the survey, and the perpendicular is six.” The specimen described, and others now before us, are essentially but dwarfed individuals of O. pectinella. Their shells, however, are smaller and thinner than in the typical form of that species, while the cost are usually simple, and the muscu- lar sears undefined. Since these features are constant in the specimens observed, it is considered advisable to recognize them as a variety of O. pectinella. Formation and locality.—Not rare in the upper portion of the Trenton shales at St. Paul, near Cannon Falls and Mineola, Minnesota; Decorah and McGregor, Iowa. Collectors—W. H. Scofield, F. W. Sardeson and the writers. Mus. Reg. Nos. 3510, 3520, 5001, 6791, 7768, 7769, 7785. ~l BRACHIOPODA. 49 Orthis (Dinorthis) meedsi.] Orvis (Dinortuts) MEEDsI W. and S. PLATE XXXII, FIGS. 39—22. 1892, April1. Orthis meedsi W.and S. American Geologist, vol. ix, p. 289. 1892, April 9. Orthis minnesotensis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences. vol. iii, p. 332, pl. v, figs. 14-17. Shell of medium size, suborbicular in outline; biconvex; anterior margin broadly deflected dorsally; hinge-line about one-fourth shorter than the greatest width. Sur- face marked by strongly elevated, sharply rounded striz, from forty-five to seventy on each valve along the anterior margin, crossed by numerous thread-like lines of growth; striae arranged in bundles of two or three, those of the ventral valve bifur- cating, while on the dorsal valve increase takes place by interpolation. Exfoliated specimens show two or three rows of small black spots, which may represent perfor- ations in the shell substance. = Ventral valve slightly convex, with a broad, shallow sinus; greatest elevation near the apex; cardinal area of moderate width, slightly concave, somewhat elevated beyond or depressed below that of the dorsal valve, perforated by a small triangular delthyrium, which is bounded on each side by a thread-like elevation; beak slightly incurved. Internal characters of valves as in 0. (D.) pectinella, but less sharply defined. Dorsal valve strongly convex centrally, with the lateral-posterior areas some- what concave; greatest elevation at a point one-third the length of the valve from the posterior margin; cardinal area very narrow, slightly concave, with a broad delthyrium, which is occupied in part by a striated cardinal process. This common and widely distributed species throughout Minnesota is probably a lineal descendant of 0. (D.) pectinella, var. sweeneyi. At first it appears rarely with that variety, and attains its distinguishing character in less than fifteen feet of shales above the horizon having var. sweeneyi in abundance, and which is here no longer met with. The feature distinguishing 0. (D.) meedsi and O. pectinella, var. sweeney? is, that bifurcation and interpolation of the striz take place at a much younger stage of growth in the former than in the latter, and therefore the species at maturity appear quite different. In some of the localities of O. pectinella this tendency towards multiplication of the striz is very noticeable, but it invariably takes place after the shell has attained more than one-half its growth. In Minne- sota specimens it takes place close to the margin, and consequently after maturity has been attained. In O. (D.) meedsi the first increase in number of striz occurs when the shell has attained but one-third its growth, and after this period bifurca- tion and interpolation are irregular. There is, moreover, a tendency towards a more convex ventral valve than in 0. (D.) pectinella, but every now and then a speci- men occurs with the characteristic flattened valve of that species. 428 THE PALEONTOLOGY OF MINNESOTA. [O. germana. The specific name is after A. D. Meeds of the University of Minnesota. Associated with the above species, at its climax of development in number of individuals, a very characteristic and striking variety makes its appearance, which is named germana. Formation and locality.—Rare near the base of the Galena shales at St. Paul, Minnesota, and McGregor, Iowa, a few feet above the horizon of O. pectinella and variety sweeneyt. It becomes a common and very characteristic fossil in the beds immediately above, and is there associated with Clitambonites diversa Shaler; it is known to extend for thirty feet above this horizon. ‘ The following are the most prominent localities at which this species has been collected: Cannon Falls, Kenyon, Warsaw. Fountain and Preston, Minnesota; Decorah and McGregor, Iowa; Neenah and Oshkosh, Wisconsin. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 4055, 5860, 5861, 6746, 7771-7785. Variety Germana W. and S. PLATE XXXII, FIGS. 48—45. 1892, Aprill. Orthis meedsi var. germana W. and S. _American Geologist, vol. ix, p. 290. This variety is distinguished from O. (D.) meedsi by the following characters: Smaller in size and squarer in outline; valves more strongly and more evenly convex; hinge areas nearly equal in width and narrower, with the beak of the ventral valve slightly elevated above that of the dorsal; ventral valve with a slight, somewhat angulated fold, while the dorsal has a shallow, but distinct sinus origin- ating immediately below the apex of the valve. The fold and sinus produce a slight sinuosity in the anterior margin, the direction of which is just the reverse of that in O. (D.) meedsi. The largest specimens of this variety observed have the general external expres- sion of small individuals of Orthis subquadrata, and no external nor internal parts are known that preclude the form from being viewed as the ancestor of that species which attains its specific development in the upper portion of the Cincinnati group The beds from which var. germana is obtained are fully one hundred feet below those holding O. subquadrata. During this interval no specimens of Dinorthis have as yet been detected. Formation and locality.—Not rare in the upper part of the Galena shales at several localities south of Cannon Falls, near Kenyon and Fountain, Minnesota. This horizon is also characterized by Anastro- phia hemiplicata and a number of small Bryozoa. Collectors.—W. H. Scofield and the writers. Mus. Reg. No. 7770. Orruis (DInoRTHIS) SUBQUADRATA Hall. PLAT XXXII, FIGS. 46—50. 1847. Orthis subquadrata HALL. Paleontology of New York, vol. i, p. 126, pl. XxxIIA, fig. 1. 1862. Orthis subquadrata HALL. Geology of Wisconsin, vol. i, p. 54, figs. 1, 2. 71863. Orthis subquadrata BILLINGS. Geology of Canada, p. 165, fig. 146. BRACHIOPODA. 429 Orthis (Dinorthis) subquadrata.] 1873. Orthis subquadrata MEEK. Paleontology of Ohio, vol. i, p. 94, pl. Ux, fig. 2. 1875. Orthis subquadrata MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 38. 1880. Orthis subquadrata WHITE. Second Annual Report, Indiana Bureau of Statistics and Geology, p. 484, pl. 1, figs. 38-5. 1881. Orthis subquadrata WuiTE. Tenth Report, State Geologist of Indiana, p. 116, pl. 1, figs. 3-5. 1887. Orthis subquadrata SHALER. Fossil Brachiopoda of the Ohio Valley, p. 22, pl. vir. 1892. Orthis (Plesiomys) subquadrata HALL. Paleontology of New York, vol. viii, pt. i, pp. 194, 197, 222, pl. vA, figs. 17-19. Original description: “Subquadrate, the cardinal line forming one side, the sides and base being nearly straight, with the angles rounded; cardinal line less than the width of the shell, extremities curved; area small, partially common to both valves; dorsal [ventral] valve nearly flat or slightly depressed near the margin, elevated towards the beak, which is small and well defined; ventral [dorsal] valve regularly convex with a shallow sinus along the center, producing a slight elevation of the dorsal valve in front; surface marked by uniform subangular radii, which bifurcate near the beak and again towards the margin, those near the cardinal line curving upwards; radii crossed by fine, elevated, concentric lines, which are very distinct in the depressions between the rays.” The following more detailed description is that of Meek, drawn up from speci- mens from typical localities: “Shell attaining about a medium size, rather distinctly resupinate, somewhat wider than long, subquadrate in general outline; moderately convex; cardinal mar- gin shorter than the breadth of the valves and rounding abruptly at the extremities into the lateral margins, which round and converge forward; front a little sinuous or straightened at the middle. “Dorsal valve more convex than the other, its most prominent part being near the middle; mesial sinus small and rather shallow, sometimes continued nearly to the umbo, or in other instances scarcely more than reaching the middle; beak very short, or little distinct from the edge of the area, and more or less arched; area narrow, directed obliquely backward and downward. Interior with scars of the adductor muscles moderately distinct, the posterior pair being situaed close back under the brachial processes, one on each side of a well defined rounded ridge that becomes suddenly smaller between the anterior pair; cardinal process rhombic, subconical, moderately prominent and having its posterior side marked by deeply impressed, divaricating striz; sockets well defined; brachial process rather strong and directed obliquely forward and laterally; internal surface, excepting the radi- ately striated front and lateral margins, nearly smooth. “Ventral valve a little convex at the umbo and flat or slightly concave between the umbo and the front and lateral margins, but sometimes having a low, very obscure mesial elevation towards the front; beak small and very short or scarcely equalling that of the other valve, arched at the apex, but not strongly incurved; area about 430 THE PALEONTOLOGY OF MINNESOTA. (Orthis (Dinorthis) subquadrata twice as high as that of the other valve, well defined, tapering rather rapidly towards the lateral extremities, arched with the beak, and directed backward and downward at decidedly less than a right angle to that of the other valve. Interior with muscular scars occupying a rather deep, bilobate impression extending nearly’ or quite to the middle of the valve and usually defined by a low ridge most distinct on each side; scars of adductor muscles small, separated by a mere trace of a raised line; those of the divaricator [diductor] muscles of moderate size, longitudinally striated and having their narrow posterior ends extending backward nearly to a small, triangular, transversely striated space [pedicle muscle scar] occupying the interior of the beak; those of the ventral adjustor muscles smaller and shorter than the divaricators [diductors] and situated nearly under the hinge teeth, which are moderately prominent, subtrigonal and oblique; vascular markings with their lateral divisions curving up backward and sending off several branches, while the other divisions extend forward and bifurcate so as to occupy the anterior region; anterior and lateral margins crenate within by very short striz. “Surface of both valves ornamented by moderately stout, radiating strizw, the posterior lateral of which curve so strongly outward that a few of them run out on the cardinal edge before reaching the lateral margins; striz of ventral valve nearly always increasing by bifurcation [some of them dividing two or three times], while those on the dorsal valve generally increase by the intercalation of shorter- ones between the larger. A few distant subimbricating marks of growth are sometimes seen towards the front and lateral margins; while, on perfectly preserved specimens, the radiating striae may sometimes be seen to be roughened by minute, elevated concentric lines, that aré more or less interrupted in crossing some of the striz.” (Pal. Ohio, vol. i, p. 94.) This species is so well known that a comparison with other related forms is unnecessary. It has been shown that O. meedsi is a development from 0. pectinella, var. sweeneyi, in which a greater number of strive have their origin at a much younger stage of growth. Moreover, as the tendency is to equalize the space between the ridges, new ones are continually added, so that these species at maturity are quite distinct. The multiplication of striz is carried still further in O. meedsi, var. germana, and in addition to this, other features are introduced which link it closely to O. subquadrata. The latter has all the characters of the former more strongly developed, which is due to its greater size, and the line of development from 0. pectinella to O. subquadrata is thus probably completed. The following species, 0. proavita, is closely related to O. subquadrata Hall. The strie are simple, and it is rare to find interpolation and bifurcation taking place BRACHIOPODA. 431 Orthis (Dinorthis) proavita .] beyond the early nealogic stage. Here, then, is a reversion to ancestral characters, which is carried still further in 0. flabellulum Hall* (non Sowerby)—0O. flabellites (Hall) Foerste,** a species from the Niagara formation much resembling 0. pectinella Emmons. Formation and locality.—This is a very characteristic and common species in America, everywhere marking the upper portion of the Hudson River group. In Minnesota it has been found abundantly at Spring Valley, and is known to be equally common at Wilmington, Illinois; Richmond, Weiseburg and Madison, Indiana; Oxford, Clarksville and Waynesville, Ohio; Maysville, Kentucky; and Anticosti. It also occurs rarely at Graf, [owa, and at lron Ridge, Wisconsin. f Collectors.—E. O. Ulrich, John Kleckler and the writers. Alsoin the collection of Dr. C. H. Robbins, of Wykoff, Minnesota. Mus. Reg. Nos. 274, 396, 4076, 4094, 7786-7788. Ortuis (Drnorrats) proavita W. and VS. PLATE XXXII, FIGS. 51—57. 1892, Aprill. Orthis proavita W.and-S. American Geologist, vol. ix, p. 290. 1892, April 9. Orthis petree SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 332, pl. v, figs. 18-21. Shell of medium size; subgaudrate; hinge-line equal to, or less than, the greatest width of the shell; cardinal anlges rounded or rectangular; sides gently convex and converging to more or less straghtened or slightly concave anterior margin. Surface marked by simple subangular strie having their origin at the apex of the valves or immediately below it, addition taking place by interpolation on the dorsal, and by bifucation on the ventral valve; one to three strize terminating on the cardinal mar- gin on each side of the umbo; thirty-seven to forty-two on mature examples, crossed by a variable number of imbricating growth lines near the anterior margin, In some specimens this margin is sharply reflexed, partly indicating old age. Ventral valve slightly elevated at the umbo, flattened or somewhat concave toward the lateral and anterior margins, with an insignificant mesial elevation. Area comparatively narrow, with a broad, triangular delthyrium, two-thirds of which is occupied by the cardinal process of the other valve; beak slightly incurved. Interior characters as in O, subquadrata, with the muscular scars remarkably well defined for a specimen of medium size. Dorsal valve more or less strongly convex, with the greatest elevation about mid-length. A shallow, or sometimes well pronounced, broad sinus is present, having its origin in the upper third of the valve. Area narrow, perpendicular or slightly inclined forward, with a broad delthyrium entirely occupied by the protrud- ing, striated cardinal process. O. (D.) proavita differs from O. (D.) iphigenia Billings,t in having the fold and sinus reversed; the latter also has a greater number of strize and is restricted to the *Geol. N. Y.; Rep. Fourth Dist.. p. 105, fig. 5, 1843: Pal. N. Y., vol. ii, pp. 254, 255, pl. x1, figs. 6, 7, 1852. ** Proc. Boston Soc. Nat. Hist., vol. xxiv, p 308, pl. vr. figs. 4, 5, 1890. + Pal. Foss., vol. i, p. 133, fig. 110, 1862 » 432 THE PALEONTOLOGY OF MINNESOTA. [Hebertella. Trenton group of Canada. 0. (D.) porcata McCoy* has deeper valves, while the area of the ventral valve is more than twice as wide. O. (D.) retrorsa Salter is a some- what larger species, but differs from O. (D.) proavita in its retrorse ventral area. For the relation of 0. (D.) proavita to other species of the subgenus Dinorthis see O. (D.) subquadrata. Formation and locality.—Not rare in the upper portion of the Hudson River group at Spring Valley, Minnesota, and Wilmington, Illinois. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 273, 278, 7789. Subgenus HEBERTELLA, Hall. 1892, Hebertella, HALL. Paleontology of New York, vol. viii, pt. i, p. 198. Original description: “This division is distinguished both by its external and internal characters; the pedicle valve has a well developed, often much elevated, cardinal area and a long, straight hinge-line; its surface is depressed-convex, always less convex than the opposite valve, which is frequently gibbous or deflected. The surface is covered with a great number of fine, rounded, closely crowded plications which increase rapidly by intercalation, and are crossed by lamellose growth lines and fine concentric striz. On the interior of the pedicle valve the teeth are large and supported by thick lamellew, which are continued as a strong ridge around a short, obcordate muscular area. This area is medially divided by a prominent ridge, upon the summit of which lies the linear scar of the adductors. The flabellate lateral impressions are sometimes divisible into their two components, diductors and adjustors, and in old individuals the impression of the pedicle muscle is often distinct. “In the brachial valve the dental sockets are narrow and are enclosed beneath and on the inner side by the strong crural plates. The cardinal process is elongate and simple, sometimes thickened, often crenulate, but not lobed, at its posterior extremity. This process unites with the inner bases of the crural plases and is pro- duced forward as a median ridge dividing the four muscular scars, which are dis- tinctly developed only in old shells. “The shell structure is fibrous-impunctate, and the plications of the surface sometimes tubulose.” Type: Orthis sinuata Hall. “Shells of this type of structure are abundant in the Trenton and Hudson faunas and extend upward into the Clinton group, but are not at present known in any later period.” * Sil, Poss. of Ireland, p. 82, pl. 11, fig. 14, 1846; and Pal. Foss., vol. i, p. 135, fig. 111, 1862, BRACHIOPODA. 433 Orthis (Hebertella) borealis.] OrtHis (HEBERTELLA) BOREALIS Billings. Fig. 33. Orthis (Hebertella) borealis Billings. a, dorsal; 6, ventral, and e, profile view of a variety of this species. Upper part of the Galena shales near Wykoff, Minnesota. Collection of E. O. Ulrich. 1859. Orthis borealis Brnuines. Canadian Naturalist and Geologist, vol. iv, p. 436, fig. 14. 1863. Orthis borealis BILLINGS. Geology of Canada, p. 129, fig. 56; p. 167, fig. 148. 1873. Orthis borealis MEEK. Palxontology of Ohio, vol. i, p. 101, pl. vit, fig. 4. 1875. Orthis borealis Mtuter. Cincinnati Quarterly Journal of Science, vol. 2, p. 28. 1889, Orthis borealis NETTELROTH. Kentucky Fossil Shells, p. 36, pl. xxxtv, figs. 14-20. 1892. Orthis (Hebertella) borealis HALL. Paleontology of New York, vol. viii, pt. i, p. 222. The Minnesota specimens of this species are closely related to Orthis plicatella of the Galena horizon, so that a detailed description is not necessary. They can be distinguished from each other by the fold and sinus, in O. borealis, being on the dorsal and ventral valves respectively, while in O, plicatella the cofiditions are the reverse. These differences are not so pronounced as in specimens from the Ohio valley, where O. borealis usually has, in addition, a much deeper dorsal than ventral valve. The latter character is one of the chief distinctions between Prof. Hall’s subgenera Hebertella and Plectorthis, and is developed at its maximum in (0. sinuata Hall. From the preceding it is readilly seen that these subgenera probably had their origin in the Chazy formation, and there and in the Trenton are not easily distinguishable, but in the Hudson River group of the Ohio valley Hebertella is one of the characteristic markers of that horizon, there reaching its maximum of growth, diversity and number of individuals. Plectorthis also attains its maximum in the Hudson River group, the tendency in the Cincinnati group being towards diminished size, but greater numerical strength and irregularity of plications, while in the north- west the radical form developed into other distinct, large, somewhat localized species. Hebertella persists into the Upper Silurian, while Plectorthis, which probably origin- ated first, became extinct with the Hudson River group. Formation and locality.—Rare in the upper Clitambonites horizon of the Galena shales near Wykoff, Cannon Falls and top of West St. Paul bluffs, in Minnesota. Prof. Whitfield mentions its occurrence in Wisconsin. Very common near the top of the Trenton limestone at Frankfort, Burgin, Lexington and elsewhere in central Kentucky. Near Nashville, Tennessee. In Canada Billings cites it from the Chazy to the Trenton at Caughnawaga, St. Genevieve, Isle Bizard and Cornwall. Collectors.—K. O. Ulrich and C. Schuchert. 434 THE PALEONTOLOGY OF MINNESOTA. (Orthis (Hebertella?) bellarugosa. Ortuis (HEBERTELLA?) BELLARUGOSA Conrad. PLATE XXXIII, FIGS. 1-4. 1843. Orthis bellarugosa CONRAD. Proceedings of the Academy of Natural Sciences of Philadelphia, vol. i, p. 333. 1847. Orthis bellarugosa IJALL. Paleontology of New York, vol. i, p. 118, pl. xxxu, fig. 3. 1892. Hebertella bellarugosa HALL. Ibidem, vol. viii, pt. i, p. 222. Original description: “Semioval; valves nearly equally convex; lesser valve with a mesial subangular furrow; ribs prominent, linear, with unequal bifurcations; disk with numerous concentric, prominent, subsquamose wrinkles; apex of larger valve not much elevated above that of the opposite valve; cardinal area.rather wide. Length, less than half an inch. “Locality: Mineral Point, Wisconsin, (Trenton limestone).” Shell subquadrate in outline; biconvex; anterior margin more or less sharply deflected ventrally. Hinge-line equal to, or a little shorter than, the greatest width of the shell. Cardinal area much the widest in the ventral valve, slightly concave and elevated above that of the dorsal. Delthyrium narrowly triangular in the ventral valve and three times as long as wide. Surface marked by unequal coste, varying in number from thirty to fifty-two, increase taking place by bifureation on the ventral valve, and by intercalation on the dorsal, crossed by numerous, strongly imbricating, concentric lines of growth. Ventral valve strongly and evenly convex, sometimes with a very shallow median sinus, greatest elevation on the umbo, with the beak more or less elevated and slightly incurved. Hinge teeth large, supported by well developed dental plates, which join the lateral elevated outer margin of the more or less obcordate muscular area. This area, in the apical portion, is occupied by the transversely striated pedicle muscle; medially by the expanding adductors, while the diductors are situated on each side of the latter. The short, conspicuous and slightly diverg- ing vascular trunks have their origin at the base of a more or less elevated muscular area and terminate rapidly. Large genital spaces are very faintly indicated on each side of the muscular area. Peripheral margin in the valves marked by prominent radiating strive. Dorsal valve convex, with a conspicuous, more or less broad, medial sinus. Cardinal area narrow, erect, slightly concave, divided by the delthyrium, which is as wide as long. Crural plates projecting and having their origin at the base of the walls of the delthyrium, which join the conspicuous, transverse apical thickening; and here the strong and simple cardinal process is centrally situated. Dental sockets deep, situated on the posterior-lateral areas of the crural plates. A stout, but short BRACHIOPODA. 435 Orthis insculpta.] and narrowly rounded medial septum has its origin at the base of the apical thick- ening, and upon each side are placed two pairs of adductor muscles, the posterior ones much the smaller. The larger specimens of this species occurring in the Trenton shales of Min- nesota are difficult to separate from Orthis insculpta Hall of the Cincinnati group. Commonly, however, the former is much smaller, has a less convex dorsal valve. with more strongly defined muscular scars; the exterior, concentric, imbricating growth lines are also more prominent. Formation and locality,—Rare in the Trenton limestone and Trenton shales at Minneapolis and St. Paul; not uncommon in the lower portion of the Galena in many localities in Goodhue county, and at Fountain, Minnesota; and Neenah, Wisconsin. Near the top of the Trenton at Decorah and McGregor, Towa. In the “Lower Blue beds” of the Trenton at Janesville, Wisconsin, and in the ‘“ Upper Buff beds” at Rockton, Illinois. Also in the ‘‘Central limestone” of the Trenton near Murfreesboro, Tennessee. Collectors.—W. H. Scofield and the writers. Mus. Reg. Nos. 6752, 7806-7812. Orvuis rnscuLtera Hall. 1847. Orthis insculpta HALL. Paleontology of New York, vol. i, p. 125, pl. xxxu, fig. 12, 21863. Orthis insculpta BILLINGS. Geol. of Can., p. 167, fig. 150. (Compare with O. bellarugosa Conrad). 1873. Orthis inseulpta MEEK. Palxontology of Obio, vol. i, p. 99, pl. TX, fig. 1. 1875. Orthis insculpta MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 40. _883. Orthis bellarugosa HALL. Second Annual Report, N. Y. State Geologist, pl. xxxv, fig. 22. 1892. Hebertella insculpta HALL. Paleontology of New York, vol. viii, pt. i, p. 222. It is peculiar that this prevalent species of the upper beds of the Hudson River formation does not occur in Minnesota, since it is found in Wisconsin and Iowa. Formation and locality —A characteristic fossil of the upper beds of the Cincinnati group in the Ohio valley; also at Wilmington, Illinois; Iron Ridge, Wisconsin, and Graf, Iowa. Mus. Reg. Nos. 7813-7815. Subgenus PLECTORTHIS, Hall. 1892. Plectorthis, HALL. Paleontology of New York, vol. viii, pt. i, p. 194. Original description: “This is a persistent form, which in American faunas, so far as known, is‘ limited to the Trenton and Hudson formations. While it retains the strong external ribs of the typical Orthis, these are not invariably simple (0. fissicosta Hall; O. triplicatella Meek; O. equivalvis Hall, not Davidson; 0. jamesi Hall); the cardinal area of the pedicle valve is comparatively low and the valves are sub- equally convex. In the interior the character of the muscular scars, dental lamelle and cardinal process is essentially the same as in Group I [Orthis callactis Dalman|; and the minute structure of the shell appears to be in precise agreement with that of O. calligramma, though no evidence of tubulose costz has been observed. In Orthis jamesi, which is placed in this association, there is occasionally a deviation toward the resupinate contour, exemplified in Groups IV and V [Orthis subquadrata Hall and Orthis sinuata Hall]. 436 THE PALEONTOLOGY OF MINNESOTA. (Orthis (Plectorthis) plicatella. Ortuis (PLECTORTHIS) PLICATELLA Hall. PLATE XXXIII, FIGS. 5—7. 1847. Orthis plicatella HALL. Paleontology of New York, vol. i, p. 122, pl. xxx, fig. 9. ?1863. Orthis plicatella BILLINGS. Geology of Canada, p. 165, fig 145. 1873. Orthis plicatella MEEK. Paleontology of Ohio, vol. i, p. 108, pl. vim, fig. 7. 1875. Orthis plic vtella MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 30. 1892. Plectorthis plicatella HALL. Paleontology of New York, vol. viii, pt.i, p. 221, pl. Vv, figs. 18-20. Original description: “Broadly semioval, nearly equivalve, length and breadth about as three to four; surface marked by strong, radiating plice, which are usually simple, about twenty to twenty-eight on each valve, crossed by simple, elevated con- centric lines, which are more distinct in the depressions between the costw, and often obscure or obsolete upon their exposed surfaces; valves nearly equally convex, without sensible depression or elevation on either one, meeting on the edges in a straight line; cardinal lines not extending beyond the width of the shell; area nar- row; dorsal foramen not extending to the beak.” This well known species originates in the lower portion of the Trenton group of New York and is also found in the inferior strata of the Galena formation in Wisconsin and Minnesota, attaining its greatest development in numbers and varia- tions in the Cincinnati group, at a horizon about 300 to 350 feet above low water in the Ohio river. Orthis plicatella is rather a rare species in the Trenton of New York, and Galena of Wisconsin and Minnesota. It attains a larger growth and is fairly constant in its simple plications and has a more depressed and furrowed dorsal umbo than in speci- mens from the Cincinnati group. The size and number of plications in the specimens from Cincinnati are very variable, several forms having been described as distinct species. These are 0. fissicosta, O. dichotoma Hall,* and 0. triplicatella Meek.** In large collections of these forms, however, it is often difficult to know where to draw the line between them, and the above names can only be used to indicate the tran- sition from the simple undivided O. plicatella to O. dichotoma with its numerous interpolated smaller striz. In the Cincinnati group of the Northwest, O. plicatella is not known to occur, but O. whitfieldi Winchell and O. kankakensis McChesney take its place. These species have attained a much larger size than O. plicatella. Formation and locality.—Rare in the Trenton limestone of Middleville and Watertown, New York, and Burgin, Kentucky. One individual has been discovered in the Galena shales at St. Paul; it has also been obtained at Kenyon, Cannon Falls and elsewhere in Goodhue county, Minnesota. Prof. Whitfleld reports it from about the same horizon in Wisconsin. Very common in the Cincinnati group around Cincinnati, Ohio. Collectors.--W. H. Scofield, A. D. Meeds and the writers. Mus. Reg. Nos. 7765, 7766, *Pal. N. Y., vol. 1, pp. 121, 125, pl xxxct, figs. 7, 13, 1847, ** Pal, Ohio, vol. {, p. 109, pl. var, fig . 8, 1872, BRACHIOPODA. 437 Orthis (Plectorthis) whitfieldi.] Orvuis (PLecTORTHIS) wHITFIELDI N. H. Winchell. PLATE XXXIII, FIGS. 8—13. 1881. Orthis whitfieldi WINCHELL. Ninth Annual Report of the Geological and Natural History Survey of Minnesota, p. 115. 1882. Orthis pectinella WHITFIELD (parti. not EMMONS nor HALL). Geology of Wisconsin, vol. iv, p. 259, pl. xu, fig. 8. 1892. Plectorthis whitfieldi HALL. Paleontology of New York, vol. viii, pt. i, p. 221, pl. v, fig. 26. Original description: “Shell semioval, the hinge-line being a little less than, or equal to, the greatest tranverse diameter, the cardinal angles being a little greater than 90°, the edge passing in a regular semioval curve through the antero-lateral angles, but sometimes with a very slight inclination in front toward the side of the receiving [ventral] valve. Size varying from nine and a half to fourteen lines in transverse diameter, and from eight to eleven and a half lines in perpendicular diameter, in the larger size the convexity being, between the umboes, six and a half lines. “The receiving [ventral] valve has a distinct and full beak and umbo, from which the surface slopes evenly to the margin all round, but having a little flatness at the cardinal angles. The cardinal area is arched, and at its union with the cardinal area of the entering [dorsal] valve forms an angle with it of nearly 90°; its bight is about one-sixth its length; its foramen [delthyrium] is triangular and reaches the beak, the width across the base being somewhat less than the hight; plications of the surface are strong, direct and simple, but double their number on the umbo by implantations, and again in the same way before reaching the margin, where they number from thirty-six to forty-eight. Between the plice are fine cross ridges which sometimes rise to the tops of the plice, but do not cross them so as to be preserved in our specimens. A cast of the interior of this valve shows a distinct general muscular impression, reaching a little more than one-third the perpendicular diameter of the valve from the beak, and divided longitudinally into shallow furrows and ridges converging within the beak, four of the former and five of the latter, witha cross-striation visible on that portion between the teeth and near the foramen. The central ridge in the general muscular impression on the cast does not reach the front margin of the scar, but gradually dies out, giving place to the adjoining parallel fur- rows which widen and coalesce, and show a longitudinal finer furrowing or striation. The next ridges, on either side, are marked and prominent, extending to the anterior angles of the scar, giving it a nearly straight, elevated front and angular corners, somewhat as in O. subquadrata. The two outermost ridges are fainter, but extend to the lateral margins of the scar. Still, outside of all these ridges are traces of a similar furrowing within the beak, embracing that portion between the teeth which 435 THE PALEONTOLOGY OF MINNESOTA. ; [Orthis (Plectorthis) whitfieldi. has the fine cross-striation. The outward plications of the valve are strongly marked on the cast for about two and a half lines from the margin, and some of them run faintly even to the edge of the muscular scar. “The entering [dorsal] valve is much less convex, but cannot be said to be flat, though it has a faint flattening along the center, which widens to the front margin where it is changed, in the large specimen, to a slight concavity and produces a straightening and also a very slight flexure of the margin. In front of the cardinal angles also, on either side, is a flat, depressed area; cardinal angle parallel with the posterior margins of the valve, and a little more than one-half the hight of that of the receiving valve; beak indistinct; foramen triangular and about as wide as high, with a small, central, smooth tooth [cardinal process], which does not rise above the plain of the area and only becomes visible on being cleaned and excavated. A cast of the interior of this valve shows marked internal characters. While the impres- sions of the individual divaricator and adductor muscles of the same side are not separable with certainty, owing to the faintness of the lines between them, the pairs of each are divided, on the cast, by a deep, sharp furrow that extends from the beak where it divides the divaricately striated cardinal process into two equal lobes, toward the front between the depressions of the hinge teeth, to a point somewhat more than one-third the diameter from the beak, where it dies away or runs into a broad, abrupt, medial depression which produces the flatness in the valve extending to the front margin. The external costz are deeply impressed on the cast about the margin, some of the lines running faintly within the vascular area. The exterior of this valve is also marked by concentric fine striations, especially between the costae.” The vascular trunks are often conspicuous in the-ventral valve, having their origin at the antero-lateral elevated margin of the muscular area; diverging slightly, they proceed but a short distance forward. Posterior to these and on each side of the muscular area are the faintly marked genital spaces. This species is closely related to O. kankakensis McChesney,* but is always pro- portionately less elongated along the hinge-line, and therefore squarer in outline. The plications are also more numerous, there being from sixty to seventy along the margin of one valve in that species, while in O. whitfieldi there are usually not more than forty. The specimen figured by Prof. Whitfield (op. cit.) as O. pectinella (Emmons) Hall, and found in the Cincinnati group at Delafield, Wisconsin, undoubtedly belongs to this species. It does not occur above the lower portion of the Galena, while O. whitfieldi is unknown below the Hudson River group, and always has a greater *New Pal. Foss., p. 77, 1861; also Tfans, Chicago Acad. Sel., vol. i, p. 20, pl. 1x. fig. 3, 1868. BRACHIOPODA. 439 Dalmanelia.] number of plications, with a convex ventral valve. In 0. pectinella this valve is flatter and its cardinal area is never so strongly elevated as in 0. whitfieldi. Formation and locality—Common in the Hudson River group at Spring V ae and near Granger, Minnesota; Delafield, Wisconsin; Savannah, Illinois, and Graf, lowa. Collectors.—E. O. Ulrich. John Kleckler, W. H. Scofield and the writers. Mus. Reg. Nos. 277, 429, 4094, 5549, 7762-7764. Subgenus DALMANELLA Hall. 1892. Dalmanella. HALL. Paleontology of New York, vol. viii, pt. i, p. 205. Original description: “Shells plano-convex or subequally biconvex. Pedicle valve usually the deeper, often gibbous, elevated at the umbo and arched over the cardinal area. Hinge-line generally shorter than the greatest width of the shell. In many of the species there is a more or less conspicuous, undefined median fold and sinus on the pedicle and brachial valves respectively. Surface covered with fine, rounded, bifurcating striez. “Tn the pedicle valve the teeth are quite prominent, thickened at their extremi- ties and supported by lamellz which are produced forward circumscribing a rather short suboval or subquadrate muscular area, which is more or less distinctly defined in different species and in different conditions of the shell. In Orthis meeki Miller, a somewhat ponderous, biconvex, multistriate variation of Orthis testudinaria, it is clearly resolvable into adjustor and diductor scars, the latter bounding, but not alto- gether enclosing the impression of the adductors; the pedicle scar is also discernable. In the brachial valve the cardinal process extends forward as a ridge to the bases of the crural plates, where it is broadened and continued thence as a median ridge separating the muscular impressions. The inner surface of this process is divided by a faint median furrow which produces two lobes at the posterior extremity, and each of these lobes is again divided, making the process quadrilobate. Sometimes the inner divisions of the two main lobes have coalesced, producing a strong median lobe and thus making the process appear trilobate. In some species at maturity, and in others from abnormal growth, this process becomes a broad plug, which fills the entire delthyrial opening. The dental sockets are small, the crural plates often greatly elevated, especially in the plano-convex forms, and they are not usually produced into a ridge about the muscular area, but end abruptly. Muscular impressions quadruplicate, sometimes with radiating ridges extending from the lateral and anterior margins. “Shell substance finely fibrous and punctate.” Species of this subgenus probably make their appearance as early as the Calcif- erous (0. electra Billings), but certainly in the Chazy group, and are also known to occur in all the intervening formations up to the close of the Devonian. 440) THE PALEONTOLOGY OF MINNESOTA. (Orthis (Dalmanella) hamburgensis. OrtTHis (DALMANELLA) HAMBURGENSIS? Walcott. PLATE XXXII, FIGS, 1416 1884. Orthis hamburgensis WALCOTT. Monograph of the U.S. Geological Survey, vol. viii, p. 73, pl. 1, fig. 5. Original description: “Shell small, suborbicular in outline, plano-convex; hinge- line a little shorter than the greatest breadth of the valves. Dorsal [ventral] valve moderately convex, most elevated a little behind the center, along a slight ridge formed by two or three strong, slightly raised strize; beak small, depressed about halfway down the cardinal margin. Ventral [dorsal] valve depressed, the slightly convex, mesial depression well defined from the beak to the front margin. “Surface of both valves marked by from twelve to eighteen strong angular strie, which increase by bifurcation or intercalation towards the margin.” The following description is based on Minnesota material: Shell very small, subquadrate in outline, hinge-line equal to, or slightly less than, the greatest width below; cardinal angles rectangular; sides in the posterior third straight or gently convex; anterior augles and front broadly rounded. Ventral valve convex, subcar- inate along the middle, with a flat slope toward the sides; greatest elevation about one-third the length of the shell from the posterior margin. Cardinal area wide, broadly triangular, slightly concave, forming an angle of about 115° with the plane of the lateral margin; delthyrium narrowly triangular, more than twice as long as wide, with a linear elevation along each wall. Beak slightly incurved, raised above that of the dorsal valve. Dorsal valve less convex than the ventral, with a sinus beginning immediatly below the beak and rapidly expanding into a broad, shallow depression, which produces a more or less undulated anterior margin. Cardinal area conspicuous, slightly concave, less than half as wide and more erect than that of the other valve; delthyrium about as long as wide, bounded on each side by a linear elevation, and occupied centrally by a narrow and simple cardinal process. Surface with moderately strong, radiating, bifurcating, angular strie, of which from thirty-two to forty-six may be counted along the anterior margin. In some specimens the striz are nearly equal in size, while in others those originating on the umbones increase rapidly in strength, and the ones coming in later by bifur- cation remain smaller, giving to such shells the appearance of striz in bundles. Interior features unknown, except that the dental plates are strong and attached to the bottom of the valve. Since the cardinal areas, delthyrium and interior characters are unknown in the Nevada specimens, the writers are not satisfied that the Trenton forms are identical with O. hamburgensis. A specimen of the latter was sent to Mr. Walcott, who writes that “the cardinal line is a trifle shorter in the Nevada specimens than in those from BRACHIOPODA. 44] Orthis (Dalmanella) testudinaria.] Minnesota, otherwise I do not see any difference between the two species. It is to be remembered, however, that the Nevada specimens do not show the cardinal area and that they are not quite as well preserved as the one you sent to me.” 0. ham- burgensis is found in the central part of the Pogonip group of Nevada, a horizon probably equivalent to the lower portion of the Chazy group of New York. The great difference, geographically and geologically, between the localities of O. ham- burgensis and the species here provisionally identified with it leads to the belief that the two may be specifically distinct. In Minnesota this form is found associated with O. testudinaria and is easily confounded with it. Upon examination, however, characters are noticed reminding one of O. tricenaria and other species referred to Orthis in its strict generic sense. The wide cardinal area, narrow delthyrium, simple cardinal process, and the fact that none of the striz terminate on the cardinal lines, are features of that genus. In O. hamburgensis the surface striz exhibit a strong tendency towards bifurcation and upon them are series of minute black spots, probably infillings of the puncte in the shell substance. Since Orthis is impunctate and always has simple plications, this species is better placed in Dalmanella. If this conclusion is correct, there is evidence to show that Dalmanella was derived from Orthis. Formation and locality.—Rare in the Trenton shales at St. Paul, near Cannon Falls, Lanesboro and Fountain, Minnesota. Also from the top of the Birdseye limestone near High Bridge, Kentucky. The typical specimens are from the central part of the Pogonip group of the Eureka District, Nevada, where the species is common. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. No. 7897. OrtHis (DALMANELLA) TESTUDINARIA Dalman. PLATE XXXIII, FIGS. 17—22. 1828. Orthis testudinaria DALMAN. Kongl. Svenska Vet.-Acad. Handl., for 1827, p. 115, pl. 11, fig. 4. 1839. Orthis testudinaria CONRAD. Annual Report of the New York Geological Survey, p. 63. 1842. Orthis striatula EMMoNs. Geology of New York; Report of the Second District, p. 394, fig. 3. 1842. Orthis testudinaria? Emmons. Ibidem, p. 404, fig. 4. 1847. Orthis testudinaria HALL. Palxontology of New York, vol. i, p. 117, pl. xxxnu, fig. 1; p. 288, pl. LX XIX, fig. 4. 1856. Orthis testudinaria BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 40, fig. 1. 1858. Orthis testudinaria RoGERS. Geology of Pennsylvania, vol. ii, pt. ii, p. 818, fig. 601. 1863. Orthis testudinaria BILLINGS. Geology of Canada, p. 165, fig. 144. 1875. Orthis testudinaria? Wuirr. Report of the U. S. Geographical Surveys west of the 100th Meridian, p. 72. 1875. Orthis testudinaria MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 20. 1882. Orthis testudinaria WHITFIELD, Geology of Wisconsin, vol. iv, p. 258, pl. xm, figs. 5-7. 1888. Orthis testudinaria HALL. Second Annual Report, New York State Geologist, pl. XxxIv, figs. 1-4, 6-15. 1884. Orthis testudinaria WALCoTYT. Monograph of the U. S. Geological Survey, vol. viii, p. 72, pl. x1, fig. 10. 1892. Dalmanella testudinaria HALL. Paleontology of New York, vol. viii, pt. i, pp. 190, 206, pl. vB, figs. 27, 39. 1892. Orthis rogata SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, : p. 331, pl. v, figs. 1-4. For other synonymy see Davidson’s Monograph of British Silurian Brachiopoda, p. 226. 449 THE PALEONTOLOGY OF MINNESOTA. (Orthis (Dalmanella) testudinaria. Original description: “O, testa confertissime striata, costis subalternis eleva- tioribus; valva minori subplana semiorbiculari; majori basi gibba, nate prominula nutante. Locus. Ostrogothia ad Borenshult, in calce cinera. Longit. 15 mm., latit. teste 15, lat. valves minoris ad basin 12 mm., crass, 7 mm. “Species quasi media inter 0. elegantulam et O. basalem, ad utraque distincta ambitu magis orbiculari, minime ad cordatum tendente, presertim vero costarum radiantium ratione, que enim duplicis sunt generis, videlicet; elevatiores (circiter 30), teste basin fere attingentes; et humiliores plus minus abbreviate, quarum 2-8, inter par priorum. “ Valva minor subplana, 1, in medio longitudina liter subimpressa; suborbicu- laris, basi truncata, apice vero rotundato, minime prominulo. Linea cardinalis quam valve longitudo manifeste brevior. Valva major basi gibba, nate prominula, modice curva valve minoris convexitatem minime attingente. Subnate areola triangularis impresso-plana, foramine deltoideo brevi. “Obs. Rostrum quam in 0. elegantula minus sed quam in O. basalis magis curv- tum; margo cardinalis quam in utraque specie brevior. Specimina plura consulti similia.”’ The following description of O. emacerata Meek (not Hall)—O. testudinaria, var. meeki Miller, is given, as it applies to this species in all of its details, except that the former is larger and more robust than in the majority of specimens usually referred to O. testudinaria: “Species small, plano-convex, rather depressed, transversely truncato-suboval, the length being about five-sixths its breadth [sometimes as wide as long]; hinge-line perhaps always a little shorter than the greatest breadth of the valves; lateral margins generally rounding to the hinge, most prominent at, or a little behind the middle, and rounding to the front, which is usually somewhat straightened, or very faintly sinuous, at the middle; or presents a regular semi- circular outline. “Dorsal valve nearly flat, or slightly convex on each side of a shallow mesial sinus, that commences very narrow at the beak and usually widens rather rapidly to the front; beak very small, scarcely projecting beyond the edge of the area, and not incurved; area low at the middle and narrowing off to nothing at the lateral extremities of the hinge, slightly arched, and directed obliquely backward; foramen [delthyrium] very small and filled by the [large trilobed, striated] cardinal process. Interior very shallow and provided with a slender mesial ridge that extends about halfway forward from the hinge, between the muscular impressions, which are not usually well defined; scars of posterior pair of adductor muscles smaller and usually deeper than the anterior and situated close back under the brachial processes; those of the anterior pair three or four times the size of the posterior [commonly not more BRACHIOPODA. 443 Orthis (Dalmanella) testudinaria.] than twice the size], suboval in form and extending to near the middle of the valve; cardinal process very small [comparatively large, striated] and trifid; brachial pro- cesses comparatively rather stout and prominent; internal surface having the radi- ating striw of the exterior rather distinctly impressed through, as it were [each with a central furrow], in consequence of the thinness of the shell, and finely granular, the granules being apparently connected with the punctate structure of the shell. “Ventral valve compressed-convex, the greatest convexity being near, or a little behind, the middle, along a more or less prominent, undefined ridge that sometimes, but not always, imparts a subcarinate appearance to the central and umbonal regions; beak small, projecting somewhat beyond that of the other valve, abruptly pointed and rather distinctly arched, but not strongly incurved; area about twice as high as that of the other valve and with its sharply defined edges sloping to the lateral extremities of the hinge, directed and arched obliquely backward with the beak; foramen [delthyrium] having nearly the form of an equilateral triangle, but rather narrowed upward to the apex of the beak [with a distinct linear ridge along each wall] and partly occupied by the cardinal process of the other valve. Interior showing the teeth to be moderately prominent; concavity for the muscular impres- sions very shallow, somewhat bifid anteriorly and not defined by a very distinct marginal ridge; at the base of the dental plates are situated the narrow adjustor scars, terminating at the transversely striated pedicle muscle, which occupies the posterior portion of the rostral cavity; on the inside of the former are the large diductors separated by the small, elongate adductors; strie and fine granules of the interior as in the other valve. “Surface of both valves ornamented by numerous, distinct radiating striw that usually bifurcate about three times between the beak and free margins; posterior lateral strie so. strongly curved that a part of them run out on the hinge-line. Numerous very minute, regularly disposed, concentric lines may also be seen by the aid of a magnifier, most distinctly defined in the furrows between the radiating strie, while a few distinct, subimbricating, stronger marks of growth are usually seen in adult shells.” Shell structure distinctly punctate. Size of shell, outline, convexity of valves and number of striz aire more or less variable features at all localities of this species. “The shells of this species usually characterize the Trenton and Hudson River beds at nearly all their outcrops, being one of the most persistent, as well as most characteristic fossils of these layers. Still, there are so many varieties of it that it is often difficult to refer it, without some hesitation, to its original place. Very many of these varieties have been described as distinct species, and others as varieties under varietal names, until 444 : THE PALEONTOLOGY OF MINNNSOTA. [Orthis (Dalmanella) testudinaria collectors have almost lost sight of the original species. Some of these varieties seem to mark given horizons over limited areas, and others apparently characterize special localities; still, I do not believe they are sufficiently distinct or persistent enough to rank as species or to be worthy a varietal name beyond the purpose of the locality where found, or for local preservation.’”’ (Whitfield, loc. cit.) Specimens of O. testudinaria from the Trenton shales and from the lower portion of the Galena formation of Minnesota are slightly smaller and narrower than those from the Trenton of New York, while in central Kentucky they are generally twice the size of the eastern examples. Other specimens from the latter region are very thin-shelled and are referred by local collectors to O. emacerata Hall. In the Cincinnati group of the Ohio valley, O. testudinaria is abundant in certain horizons. It is, moreover, nearly always present in one form or another throughout the formation and is more or less variable, although constant in its characters in certain beds. Some varieties are known as 0. cyclus James, O. multisecta (James) Meek, O. emacerata Hall, O. jugosa James and O. meeki Miller. The first two are synonymous and cannot be regarded as of greater significance than a local variation; the same is also true of the last two. O. emacerata can be distinguished from O. testudinaria by its thin, compressed valves and finer and more numerous striw. If, however, a close examination is made between specimens of 0. testudinaria from various localities it will be apparent to the observer that individuals from one region do not exactly agree with those from another. As long as one restricts himself in his studies of this species to a single horizon of one locality all goes well with the selected varieties, but as soon as the trial is made to apply them to specimens from other regions the chosen varieties drop out for want of constancy of characters. In some Minnesota specimens there is a tendency to greater convexity of the dorsal valve. The mesial sinus may be obsolete or, as seen in one specimen, narrow and deep, sharply indenting the anterior margin. Probably if the develop- ment of the sinus were to become deeper and deeper in successive generations, it would eventually result in a species related to Bilobites. The general expression of 0. testudinaria and species of Bilobites, excluding the strongly lobate condition of the latter genus, is essentially the same. While this may be the line of development, still Bilobites may have originated from an entirely different stock. Dr. Beecher, in his “Development of Bilobites,” has suggested its relations to the group represented by Platystrophia biforata Schlotheim.* Formation and locality.—Not common in the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Chatfield, Preston and elsewhere in Minnesota; Decorah and McGregor, Iowa. Very common in the Galena shales at various localities in Goodhue and Olmsted counties, Minnesota. Also from the base of the “ Upper Buff beds” of the Trenton at Mineral Point, Wisconsin, and Rockton, Illinois. From the Galena at Decorah and Dubuque, Iowa; Neenah and Oshkosh, Wisconsin. In the Trenton Jimestone of *American Jour. Sci., vol. xlli, p. 54, 1891. BRACHIOPODA. 445 Orthis (Dalmanella) testudinaria, var. emacerata.] central Kentucky, and near Nashville, Tennessee; New York and eastern Canada. In the Salmon River group, or Lorraine shales, at Graf, Iowa; Iron Ridge, Wisconsin; Cincinnati, Ohio; New York; Anticosti, and Silver City, New Mexico; Chazy groupof New York and Canada. It is also found in Lower Silurian rocks in England, Scotland, Ireland, Sweden and on the island of Sardinia. Mus. Reg. Nos. 790, 3511, 4035, 5856, 6766, 6806, 7892-7896, 7898-7909. Ortuis (DALMANELLA) TESTUDINARIA, Var. EMACERATA Hall. PLATE XXXIII, FIGS. 23 and 24. 1860. Orthis emacerata HALL. Thirteenth Report, N. Y. State Cabinet of Natural History, p. 121. 1862. Orthis emacerata HALL. Ibidem, Fifteenth Report, pl. 11, figs. 1-3. 1862. Orthis emacerata BiLLines. Canadian Naturalist and Geologist, vol. vii, p. 393. 1874. Orthis cyclus JAMES. Cincinnati Quarterly Journal of Science, vol. i, p. 19. 1875. Orthis emacerata MILLER. Ibidem, vol. ii, p. 24. 1883. Orthis emacerata HALL. Second Annual Report, New York State Geologist, pl. xxxrv, figs. 14, 15. 1892. Dalmanella emacerata HALL, Paleontology of New York, vol. viii, pp. 207, 224, pl. vC, figs. 1, 2. 1892. Orthis macrior SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p- 330, pl. v, figs. 5-7. Original description: “Shell semielliptical, length and width about as five to seven; hinge-line nearly equaling the width of the shell. Dorsal valve flat, with a slight depression down the center; area extremely narrow. Ventral valve depressed- convex, slightly elevated at the beak, which is inclined over the area, but scarcely incurved; an undefined elevation, extending from the umbo toward the front and sometimes quite to the margin of the shell; area narrow, almost linear. “Surface finely striated; strie bifurcating, curving upwards and running out on the hinge-line. Interior of the dorsal valve with two small teeth and a small cardinal process; valves thin. “This species has the form and general characters of Orthis testudinaria, but the shell is much thinner than that species ordinarily is in the same formation, and the strie are finer, there being at least twenty more on the margin in shells of equal size. The depression in the center of the dorsal valve and elevation in the center of the ventral valve are far less conspicuous or scarcely marked in some specimens, while the hinge-line is always proportionately longer than in 0. testudinaria.” For further remarks see O. testudinaria. Formation and locality.—Rare in the Hudson River group at Spring Valley and Granger, Minnesota. It is common at Cincinnati at a horizon about 300 feet above the low water mark of the Ohio river; St. Croix, Quebec. Collectors.—W, H. Scofield and the writers. Mus. Reg. Nos. 7917, 7934. OrTHIs (DALMANELLA) TESTUDINARIA, var. MEEKI Miller. PLATE XXXIII, FIGS. 25—29. 1873. Orthis emacerata MEEK (non Hall). Palwontology of Ohio, vol, i, p. 109, pl. vim, figs. 1, 2. 1875, Orthis meeki MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 20. 446 THE PALEONTOLOGY OF MINNESOTA. {Orthis (Dalmanella) subaquata, 1879, Orthis jugosa JAMES, The Palxontologist, No 4, p. 31. 1892. Dulmanella meeki HALL. Paleontology of New York, vol. viii, pt. i. pp. 206, 224, pl. ve, fig. 3. 1892. Orthis corpulenta SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 380, pl. v, figs. 8-10. This variety is restricted to the upper portion of the Hudson River group and can be distinguished from 0. testudinaria Dalman by the following characters: Attains a larger size; valves thicker and more convex; cardinal areas wider and shorter; strie coarser in all stages of growth, with a larger number terminating on the cardinal lines; in the dorsal valve the muscular scars are more distinctly defined and often much thickened and elevated around the margin. Formation and locality—In the Hudson River group at Spring Valley, Minnesota, this variety oceurs in great numbers; also in the upper portion of the same formation at Oxford, Clarksville and elsewhere in Ohio. Collectors.—W. H. Scofleld, E. O. Ulrich and the writers. Also in the collection of Dr. C. H. Robbins, of Wykoff, Minnesota. Mus, Reg. Nos. 281, 236, 272, 4078-7985. Ortuis (DALMANELLA) SUBHQUATA Conrad. PLATE XXXIII, FIGS. 30-36, 1843. Orthis subequata CONRAD. Proceedings of the Academy of Natural Sciences of Philadelphia, vol..i, p. 333. 1847. Orthis subeequata HALL. Paleontology of New York, vol. i, p. 118, pl. xxxu, fig. 2. 1862. Orthis subequata HALL. Geology of Wisconsin, vol. i, p. 42, figs. 1-3, and p. 436. 1880. Orthis minneapolis N. H. WINCHELL. Eighth Annual Report of the Geological and Natural History Survey of Minnesota, p. 63. 1883. Orthis perveta HALL. Second Ann. Rept., N.Y. State Geologist, pl. XXXIV, figs. (?16,) 17, 18. 1883. Orthis subcequata HALL. Ibidem, pl. Xxxtv, figs. 19-24. 1892. Dalmanella subequata HALL. Palxontology of New York, vol. viii, pt. i, pp. 194, 207, 224, pl. vc. figs. 6-11. 1892. Dalmanella perveta HALL. Ibidem, p. 224, pl. vC, figs. 13, 14. Original description: “Semioval; valves ventricose, subequal; lesser valve with a slight subangulated mesial furrow; larger valve prominent in the middle, with flattened sides; radiating strize fine, closely arranged, unequal, rounded; cardinal area rather wide; apex of large valve prominent, not profoundly elevated above the opposite beak; the dorsal margin concave. Length, half an inch.” Adult shells vary considerably in size; biconvex, sometimes as wide as long, but generally attaining a greater breadth than length. In very young examples the hinge-line is as long as the greatest width; while in large and obese individuals it is only three-fifths of the breadth. Cardinal angles varying from acute to subacute and sometimes slightly rounded; lateral and anterior margins broadly and evenly rounding, the latter usually broadly, but slightly, deflected dorsally. Surface with fine striz, tubulose, bifurcating about twice. In the ventral valve they are less numerous down the middle, but increase in size and have, at varying intervals, very oblique, large openings. At the base of these parforations the striz BRACHIOPODA. 447 Orthis (Dalmanclla) subequata,] are reduced in size and commonly open again near the anterior margin. On each side of the median area the striz are finer, more numerous and rarely tubulose. In some specimens, however, the perforations are more prolific near the cardinal margin, In the dorsal valve the arrangement of the larger and smaller striz is the reverse of that in the other valve. The finer, less tubulose ones are developed medially, while those perforated and larger are situated laterally. Concentric lines excessively fine, with a few coarser lines of growth near the anterior margin. Shell structure finely punctate. Ventral valve strongly and evenly convex, usually with a broad, shallow sinus; anterior margin slightly prolonged upward to correspond with the concavity in the dorsal valve; point of greatest elevation about mid-length, or somewhat posterior; apex greatly depressed. Cardinal area well developed, broadly triangular, elevated, slightly convex and striated; delthyrium triangular, with straight or slightly convex sides about twice as long as wide, the apex being occupied by a short plate or slightly filled with shell matter. Interior with strong dental processes, supported by well developed plates, which join the more or less strongly elevated postero-lateral mar- gins of the muscular impression. Muscular area elongate, lobate, distinctly limited by a raised margin in thick shells, while in thin ones the anterior edge may be obso- lete, the center being occupied by the elongate adductors. The latter are medially divided by a linear ridge, which in some specimens is well developed, separating the scars in front and continuing as a strong septum to near the anterior margin. Outside of the adductor scars are situated the diductors and adjustors, the latter being well defined only in thick shells; pedicle muscle located in the apex of the delthyrium, which may be either a thickening in that part of the shell or a short, transverse, flat plate, similar to a delthyrium, with its anterior portion inwardly directed and transversely striated. Genital spaces indicated on each side of the musular area in thick shells. In such specimens the anterior margin is slightly thickened and grooved, while in thin valves the entire interior is faintly striated, conforming with the striz of the outer surface. Dorsal valve evenly convex, but not as deep as the ventral. In some specimens there is a shallow and narrow medial depression, which has its origin immediately below the beak and becomes obsolete near the mid-length or shortly anterior to it. Cardinal area narrow and concave; delthyrium triangular, as wide as long, with a linear elevation along each wall and centrally occupied by a small, faintly bilobed, sometimes striated, cardinal process, which is anteriorly drawn out into a short, slender septum. Crural processes strong and curving upward; with deep dental sockets situated postero-laterally. The former are supported by strong plates, which also form the walls of the delthyrium and are attached to the bottom of-the 448 THE PALEONTOLOGY OF MINNESOTA. LOrthis (Dalmanella) subaequata. valve. The delthyrial cavity is more or less thickened, excavated anteriorly and produced centrally into a low, but distinct, median septum, which terminates at about the mid-length of the valve and separates the two paris of adductor scars, the posterior pair being slightly smaller. When the scars are more divergent than usual the septum is thickened laterally and fills the space left between the anterior pair. Surface in front of the scars marked with a few faint, short, radiating lines of the vascular system. This widely distributed species is nearly always prolific in individuals at most localities and varies considerably in outline, number of striz and in the mesial fold and sinus. The writers have several hundred examples, together with the varieties conradi, perveta, gibbosa and circularis, the greater number of which were collected in Minnesota, though specimens were also obtained from Canada, Kentucky, Tennessee, Illinois, lowa and Wisconsin. In southern localities the circular form prevails, while in the northwest the species is commonly wider than long. In the Black River limestone of eastern Canada, a well developed fold and sinus, combined with a more or less short hinge-line, is the local change. "These varieties also occur in the Trenton shales between the cities of Minneapolis and St. Paul, and are often not sufficiently constant to permit the positive separation of a large lot of individuals. This, how- ever, is to be expected in any prolific and plastic species. The specimens with coarse strive are separated as var. perveta; those with a more or less profound and angulated sinus are referred to var. gibbosa, while the circular forms, with fine and equal striz, are placed in the variety circularis. The types of Conrad’s O. perveta and O. subequata, now preserved in the American Museum of Natural History in New York city, have been compared with similar speci- mens from Mineral Point, Wisconsin, the original locality, and no specific differences between them have been made out. In Pal. New York, vol. i, O. perveta is figured as a small species, but in the Geol. of Wisconsin, Prof. Hall states that it attains a width of one inch. Numerous specimens, however, occur at Mineral Point which agree with the above illustrations of Conrad’s type of O. perveta. These appear to be adult individuals and were probably so regarded by Conrad, as shown by the specific name. They differ from O. subequata only in having coarser strie, and the name perveta is retained for them as a variety. O. minneapolis Winchell proves to be identical with O. subequata, while O. conradi Winchell, was applied to a small but mature form of the same species occurring in abundance in the Trenton limestone. Formation and locality.—Rare in the Trenton limestone at Minneapolis and Rochester, Minnesota. Common in the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Lanesboro, St. Charles, Eyota, Fountain, Fremont, Chatfield, Preston and near Caledonia, Minnesota; Decorah and McGregor, Iowa. Near the base of the Upper Buff limestone at Mineral Point, Wisconsin; Auburn, Lincoln county, Missouri. “Of O. subeequata I have seen only a single specimen. It was found in an old quarry two miles north of Montreal.” (Billings, Can. Nat. Geol., vol. iv, p. 434.) Collectors.—Miss C.S. Seymour, H. V. Winchell, W. H. Scofield, W. H. Shelton, C, L. Herrick, BE. O. Ulrich and the writers. Mus. Reg. Nos. 321, 346, 374, 644, 648, 707, 720, 737, 739, 766, 789, 794, 3518, 3519, 4032, 4056, 4939, 4943, 4975, 4976, 5058, 5093, 5581, 5671, 6775, 6792, 6801, 6803, 7915, 7959-7968, BRACHIOPODA. 449 Variety conradi.] Variety conrapt N. H. Winchell. PLATE XXXIII, FIGS. 37—39, 1880. Orthis conradi N. H. WincHELL. Eighth Annual Report of the Geological and Natural History Survey of Minnesota, p. 68. Original description: “Shell having the shape and size of Orthis disparilis (Con.), but with a moderately convex entering valve, with from fifty to sixty fine radiating strie on each valve, about half of which disappear before reaching the beak; foramen of the larger valve narrow, of the smaller valve triangular; surface with indistinct growth-bands, but without evident interradial crenulations; on the center of the smaller valve is a flattening that widens from the beak and disappears before reach- ing the margin.” In the upper portion of the Trenton limestone at Minneapolis, Minnesota, and Decorah, Iowa, also in the “Lower Blue beds” of Wisconsin at Janesville and Beloit, a small form of Orthis, belonging to the O. perveta group, is constantly met, and to this the name 0. conradi has been applied by one of the writers. A similar species has been described by Mr. Billings as 0. electra,* and was procured in the upper part of limestone No. 2 of the Quebec group at Point Lévis, Canada. Although these speci- mens are from a much lower horizon than the present material, yet the size and general external expression are strikingly similar. Of this species Billings writes: “The only differences that can be made out from a comparison with specimens [of O. perveta] from-Tennessee and the figures given by Hall in the Paleontology of New York are, that in O. perveta the dorsal valve is more convex than it is in O. electra, and the beak of the ventral valve not so depressed, while at the same time it is more extended. At present I have no means of comparing the interior of the two species. When such a comparison can be made, should no greater differences be disclosed than are afforded by the external characters, I would be disposed to unite the two under one name.” (Pal. Foss., vol. i, p. 80.) Some northwestern specimens have the beak as much depressed as in 0. electra. However, it is usually, if not always, more extended than in the latter species, while the dorsal valve seems to be more convex. Dr. White** has doubtfully identified 0. electra as occurring at Fish Spring, House range, Utah. The greater length of the hinge-line, 16 mm. in these specimens, compared with the figures of Canadian examples, the largest of which are only half that length, precludes the possibility of their being alike. The char- acters by which the northwestern shells can be separated from 0. electra are internal. The latter is described as having the dental plates scarcely developed, while no * Pal. Foss., vol. i, p. 79, fig. 72, and p. 217, 1862. ** Report of U. 8. Geog. Surv. west 100th Meridian, vol. iv, p. 55, 1875. 29— 450 THE PALEONTOLOGY OF MINNESOTA. ¢ [Variety perveta. divaricator process was seen in any silicified specimens observed. In O. subaquata, var. conradi, these parts are comparatively as strongly developed as in any of the larger forms of this species occurring in the shales above. These small specimens are regarded as mature but dwarfed individuals of O. subequata, and since they hold a constant horizon over a great area, the varietal name conradi will serve to distinguish them from the other varieties of this species. Formation and locality.—Common near the top of the Trenton limestone at Minneapolis, Minnesota; and Decorah, Iowa. Also in the ‘‘ Lower Blue beds” of the Trenton at Janesville and Beloit, Wisconsin. “Tn certain beds of the Chazy limestone there are multitudes of a small Orthis which have, as nearly as I can judge, precisely the form and dimensions of 0. perveta, but, in consequence of their being imbedded in a rather compact subcrystalline rock, I have not been able to procure any specimens with the surface well preserved.” (Billings, Can. Nat. and Geol., vol. iv, p. 434.) These localities are two miles north of Montreal, Canada, and two or three miles west of Chazy, New York. This same form is believed to be the one identified by Mr. Walcott as O. perveta, which also occurs abundantly in the upper beds of the Pogonip group in Nevada. (Mono. U.S. Geol. Survey, vol. viii, p, 72.) Collectors.—O, L. Herrick, E. O. Ulrich and the writers. Mus. Reg. Nos. 651 (type specimen lost), 753, 5072, 5094, 7978-7982. Variety PERVETA Conrad. PLATE XXXIII, FIGS. 40—42. 1843. Orthis perveta CONRAD. Proceedings of the Academy of Natural Sciences of Philadelphia, vol. i, p. 333. 1847. Orthis perveta HALL. Paleontology of New York, vol. i, p. 120, pl. xxxu, fig. 5 1859. Orthis perveta BILLINGS. Canadian Naturalist and Geologist, vol. iv, p. 434, fig. 10. 1862. Orthis perveta HALL. Geology of Wisconsin, vol. i, p. 42, fig. 7. 1863, Orthis perveta BILLINGS. Geology of Canada, p. 130, fig. 57. 1880. Orthis media N. H. WiINcHELL. Bighth Annual Report of the Geological and Natural History Survey of Minnesota, p. 64. 1880. Orthis kassube N. H. WINCHELL, Ibidem, p. 65. 21884. Orthis perveta WaLcorr. Monograph of the U.S. Geological Survey, vol. viii, p. 72, pl. Xt, fig. 3. 1892. Orthis (Dalmanella) perveta HALL. Paleontology of New York, vol. viii, pt. i, pl. vC, fig. 12. Original description: “Transversely oval, wider than the length of the hinge- line; valves slightly ventricose, subequal, with numerous prominent radiating stric, bifurcated on the umbo; larger valve ventricose in the middle, with a slight central depression; sides somewhat depressed; the opposite valve flattened towards the base and depressed to correspond with the elevation of the other valve, forming a sinuous margin when viewed in profile; base truncated; superior lateral margin obliquely truncated, rounded inferiorly. Length, one-third of an inch; breadth, nearly half an inch, “Locality: Mineral Point, Wisconsin, (Trenton limestone).” This variety can readily be distinguished by its coarser stria. The fold and sinus are also usually more pronounced than in 0. subequata, and occasionally are developed equally as strong as in var. gibbosa, when it is impossible to separate it from the latter. In Minnesota these shells are much distorted by pressure, a peculi- arity at once striking. Well preserved specimens, however, show close relationship BRACHIOPODA. 451 Variety gibbosa.] to O. subequata. The specimens illustrated by Mr. Walcott (/oc. cit.) and occurring abundantly in the upper beds of the Pogonip group—Chazy group of New York, seem to agree better with var. conradi Winchell. Formation and locality.—In Minnesota this form is first met with at the top of the Trenton limestone, where it is fairly abundant, but usually much crushed; thence it extends upward:in the Trenton shales. It has been collected at, Minneapolis, St, Paul, Cannon Falls, Lanesboro and Fountain, Minnesota; Decorah, Towa. In Wisconsin it has been-found in the ‘‘ Lower Blue beds” and near the base of the ‘‘ Upper Buff beds” at Mineral Point, Janesville and Beloit; Dixon, Illinois. In the Glade limestone of middle Tennessee the variety seems to be rare. It is probably this form of O. subequata that also occurs in northern New York and eastern Canada. Collectors.—C, L. Herrick, W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 186, 322, 336, 643, 3514, 4032, 5147, 5148, 7973-7977. Variety eissosa Billings. PLATE XXXIII, FIGS. 43—45. 1857. Orthis gibbosa BILLINGS. Geological Survey of Canada; Report of Progress for 1856, p. 296. 1859. Orthis gibbosa BILLINGS. Canadian Naturalist and Geologist, vol. iv, p. 434. 1892. Dalmanella gibbosa HALL. Paleontology of New York, vol. viii, pt. i, p. 224. Original description: ‘About the size and shape of Orthis testudinaria, but with both valves convex; greatest width at the center or a little in front of the center of the length, above which the sides are somewhat straight and converging to the extremities of the hinge-line, the latter about one-sixth shorter than the greatest width; the front margin very broadly rounded; almost straight or even slightly sinuated in some specimens for one-third of the width in the center; front angles well rounded; the ventral valve is depressed, pyramidal, most elevated at about one line from the beak, which is small, pointed and but slightly incurved; a broad shallow [often pronounced] mesial depression occupies the front of this valve, but disappears usually at one-half the distance to the beak; cardinal area triangular at the base, nearly at right angles to the plane of the margin, but curved over above, owing to the backward projection of the beak. Dorsal valve exceedingly convex in most specimens; greatest elevation about the center, often a barely perceptible broad mesial elevation towards the front; cardinal area small, lying in the plane of the margin; beak very small and scarcely projecting from the upper edge of the area; the whole surface is covered with fine stria, which are about twice sub-divided; the ‘cast of the interior of the ventral valve shows that the muscular impressions were bordered by strong lamelle extending downward, slightly converging at three lines from the beak; in a specimen eight lines wide they were separated by a median ridge with a broad base and sharp edge; width of large specimens, eight lines; length, six and a half.” : Walter R. Billings has kindly presented to one of the writers specimens of 0. gibbosa from the Black River limestone near Ottawa. These prove to be very closely 452 THE PALEONTOLOGY OF MINNESOTA. {Variety circularis. related to O. subequata and O. perveta Conrad. E. Billings states that* “it is distin- guished from O. subaquata by having a broad, shallow, mesial sinus in the front half of the ventral valve. * * * It may be that, by comparison with extensive series of western specimens, these three species might be united. I shall, for the present, keep them separate provisionally.” In Minnesota specimens occur which are identical with the O. gibbosa before us. The sinus toward the anterior margin is often profound in strongly convex specimens with angular sides, producing a fold in the dorsal valve which is distinctly limited laterally. For such shells we have retained the varietal name gibbosa. These and var. perveta at times merge into each other to such a degree that it is impossible to separate them. Formation and locality —Not uncommon in the Trentou shales at Minneapolis, Chatfield, Lanesboro and Cannon Falls, Minnesota; Decorah, Iowa. One specimen has been found in the ‘‘ Lower Blue beds” at Mineral Point, Wisconsin. ‘0 gibbosa occurs rarely in the Chazy limestone, island of Montreal; abund- antly, but badly preserved, at the Pallideau islands, lake Huron, in rocks which are either Chazy or Black River. At La Petite Chauditre rapids near Ottawa, and at the fourth chute of the Bonne-chtre, in the Black River limestone, and in the Trenton limestone at Bellville, Canada.” (Billings, Can. Nat. Geol. vol. iv, p. 435.) Collectors.—W. H. Scofield and the writers. Mus. Reg. Nos. 4032, 5510, 7969-7772. Variety crrcutaris N. H. Winchell. ‘PLATE XXXIII, FIGS. 46 and 47. 1880. Orthis cireularis N. H. WINCHELL. Highth Annual Report of the Geological and Natural History Survey of Minnesota, p. 66. Original description: “Shell subcircular, the greatest diameter being from just in front of one cardinal angle to the antero-lateral margin on the opposite side; hinge-line about one-half the greatest diameter; along the front margin is a very slight inclination toward the smaller valve, but the valves are otherwise uniformly convex; umbo of the receiving [ventral] valve prominent and full, but the beak low and arched over the cardinal area; the other valve less elevated in the umbo and the beak less prolonged, but slightly incurved over the hinge-line; the open foramen [delthyrium] of the receiving valve long and narrow, with an obtuse apex, but two or three times as wide at the base as at the top; surface marked by numerous fine rays which, bifurcating once or twice between the umbo and the free margin, are subequal at the middle of the front margin and number six or seven in the space of one line, two or three curving backward from the beak and terminating on the hinge area. These rays are crossed by fine concentric lines, only visible in fresh specimens and under a magnifier, and by distant dim growth bands, which latter begin on the umbo; diameter, about half an inch. Interior unknown.” *Oan. Nat. and Geol., vol. iv, p. 484, 1859. BRACHIOPODA. 453 Orthis (Dalmanellu) amcena.] Vairety circularis is distinguished by its subcircular outline, usually smaller size and very fine, equal and more numerous striz, a greater number of which terminate on the cardinal line. The tubulose character of the striz is also developed, but it is never a conspicuous feature. Occasionally specimens will be found with very fine strize, which are, however, larger and wider than is usual in this variety. O. subequata, var. circularis, attains its maximum development in individuals in the “Glade limestone” in Tennessee, and is there somewhat coarser in its strie. Formation and locality.—Not rare in the upper part of the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Rochester and Fountain, Minnesota. Rare near the top of the Birdseye limestone two miles south of High Bridge, Kentucky. Common in the ‘‘Glade limestone” at Lebanon and elsewhere in middle Tennessee. Collectors.—W. H. Scofield, E. O. Ulrich and the writers. Mus. Reg. Nos. 279, 346, 3515, 4049, 4935, 5149, 6778, 6804. Ortuis (DALMANELLA) AamM@NnA N, H. Winchell. PLATE XXXIII, FIGS. 48 and 49, 1880. Orthis amena N. H. WINCHELL. LHighth Annual Report of the Geological and Natural History Survey of Minnesota, p. 65. Original description: “Shell transversely oval with a hinge-line that compares to the greatest diameter about as five to nine. Evenly rounded from the cardinal extremities, which hardly disturb the symmetry of the outline, through the front margin; valves nearly equal; umbonal region of the receiving [ventral] valve sur- rounded by a depressed or somewhat concave border, which in the front margin becomes flat or inclines toward the entering [dorsal] valve; the entering valve having a much less marginal concavity, but being moderately and evenly convex; cardinal areas small; foramen [delthyrium] also small; beak of the receiving valve somewhat incurved; that of the entering valve small, but abrupt and distinct, surface marked by rays which are doubled or tripled in number on the umbo by implantation, but maintain a larger size than the rest in passing to the margin, several of which are also curved so as to run out in the hinge-line; transverse diameter, nine to ten lines; perpendicular diameter from seven and a half to eight and a half lines. Interior unknown.” — Two somewhat compressed type specimens are the only ones known of this species. They differ but slightly from O. subequata, as the strive which originate on the umbo increase in prominence to the anterior margin, between which are two or three smaller ones. A very similar striation is seen in O. (D.) stonensis Safford, a species also belonging to the O. subequata section, but always smaller and narrower than O. amena Winchell. 454 THE PALEONTOLOGY OF MINNESOTA. (Platystrophia. These specimens are supposed to have been derived from the Galena limestone, and no others of the type of O. subequata occurring in this formation are known. Formation and locality.—Rare in the Galena limestone(?) near Spring Valley, Minnesota. Collector.—N. H. Winchell. Mus. Reg. No. 642. Subgenus PLATYSTROPHIA, King, 1850. Platystrophia, Kine. Monograph of the Permian Fossils of England, p. 486. 1892. Platystrophia, HALL. Paleontology of New York, vol. viii, pt. i, p. 200. Description: “The name Platystrophia, proposed by Dr. King, has come into very genera! use for a group of orthids having a strikingly spiriferoid exterior. The hinge-line and area are long and straight and nearly equally developed on the two valves. Both are very convex, the brachial being the more so and bearing a very strong median fold corresponding to a deep sinus on the opposite valve. The valves are marked by strong, sharp plications which extend over the fold and sinus, and the external surface is finely granulose, the latter feature being rarely well retained. This peculiar exterior, so unlike anything met with elsewhere in the genus Orthis, readily deceived earlier writers into referring the species to Delthyris or Spirifer, and Mr. Davidson was the first to demonstrate* the true generic value of its internal and more essential characters. These are not materially different from those already described in the group of Orthis occidentalis. The delthyrium is open in both valves, being somewhat larger in the pedicle valve, and in old and gibbous shells of Orthis lynx has often encroached to a considerable extent upon the umbonal region of the valve. The teeth are thick and very prominent, the muscular area comparatively small, but usually deeply excavated in the substance of the shell and not readily divisible into the component scars. In the brachial valve the car- dinal process is a simple linear ridge, always small and sometimes nearly obsolete. The dental sockets are comparatively small, the crural plates large and thick, uniting at their inner bases and produced into a prominent median ridge. The muscular area is quadruplicate and indistinct, The shell structure is very compact and finely fibrous, without punctation.” Type: Terebratulites biforatus Schlotheim. “The genus appears in American faunas first in the Chazy and ranges upward into the Clinton and Niagara groups, attaining a great development in individuals and variety in external form in the Trenton—Hudson River fauna. It has also a considerable vertical range in the Silurian of Great Britian, Mr, Davidson citing it from the Caradoc, Upper and Lower Llandeilo and the Wenlock.” (Hall, op. cit.) * Bull. Soc, Géol. de France, sec. ser,, vol. xxi, 1848, or BRACHIOPODA. Af Platystrophia biforata.] PLATYSTROPHIA BIFORATA Schlotheim, sp. PLATE XXXIII, FIGS. 49—82. 1820. Yerebratulites biforatus ScHLOTHEIM. Petrefactenkunde, p. 265. For other European synonomy see Davidson’s Monograph of British Silurian Brachiopoda, pt. Vii, p- 268, 1866-1871. 4 1843. Spirifer sheppardi CASTLENAU. Nssai sur le Systeme Silurien Septentrionale, p. 42, pl. XIV, fig. 15. 1843. Delthyris brachynota HALL. Geology of New York; Report Fourth District, p. 70, fig. 6 1844. Orthis and Delthyris OwEN. Geological Exploration of Lowa, Wisconsin and Illinois, pl. xy, figs. 3, 7. 1847. Delthyris lynx HAL (partim) (non ErcHwALpD). Paleontology of New York, vol. i, p. 133, pl. XxxuD, fig. 1. 1852. Spirifer biforatus, var. lynx HALL. Ibidem, vol. ii, p. 65, pl. X x11, fig. 1. 1856. Orthis biforata BILLINGS. Canadian Naturalist and Geologist, vol. i, p. 206, figs. 6-10. 1863. Orthis lyne BILLINGS. Geology of Canada, p. 167, fig 149. 1865. Platystrophia regularis SHALER. Bulletin of the Museum of Comparative Zoology, p. 67. 1873. Orthis (Platystrophia) biforata MEEK. Paleontology of Ohio, vol. i, p, 112. 1874. Orthis biforata NICHOLSON and HinpE. Canadian Journal, vol. Xiv, p. 158. 1875. Orthis lynx MILLER (partim). Cincinnati Quarterly Journal of Science, vol. ii, p. 25. 1875. Orthis biforata WHITE. Report of the U. 8. Geographical Survey west of the 100th Meredian, ; vol. iv, p. 74, pl. 1v, fig. 9. 1883. Orthis (Platystrophia) biforata, var. lynx HALL. Second Annual Report, New York State Geologist, pl. 'xxxv, figs. 11-14 (not figs. 9, 10, 15 of pl. Xxxv, and fig. 30 of pl. xxx1v—P. biforata, var. lyna). 1885. Orthis biforata, var. lynx, forma reversata and daytonensis FOERSTE. Bulletin of the Denison University, vol. i, pp. 81, 82, pl. x11, figs. 7, 8. 1889. Orthis biforata NETTELiOTH. Kentucky Fossil Shells, p. 35, pl. XXIX, figs. 18-29. 1890. Orthis biforata-FOERSTE. Proceedings of the Boston Society of Nat. Hist., vol. xxiv, p. 312. 1892. Platystrophia lynx HALL. Paleontology of New York, vol. viii, pp. 202, 223, pl. VB, fig. 10. Description: Since the original description of this species is not accessible, that by Davidson (op. cit. p. 269) is here reproduced: “Transversely semielliptical or subquadrate, wider than long, more or less globose, the Jength, width and depth varying sometimes but little; hinge-line more often rather less than the width of the shell, sometimes slightly exceeding the general breadth, with short, acute mucronate wings, or rounded terminations; in front the ventral valve is abruptly deflected and indents the opposite one; beaks in both valves much incurved and approximating. Ventral valve convex, witha wide, deep medial sinus, commencing at the extremity of the beak and widening as it nears the front. Area triangular of moderate hight, fissure [delthyrium] open, beak angular, incurved. Dorsal valve deeper than the opposite one, at times gibbous, with a wide longitudinal fold, com- mencing at the extremity of the umbonal beak and extending to the front; area a little less wide than in the opposite valve, [erect], fissure [delthyrium] open. Surface of both valves ornamented with a greater or lesser number of radiating triangular ribs; of these from one to five (and in some varieties more) [in American forms usually three] furrow the medio-longitudinal sinus, while from two to six or seven [usually four in this country] compose the mesial fold. The valves are also crossed at intervals by numerous concentric, raised, subimbricating lines; the surface is also marked with small punctures [in well preserved specimens the surface is crowded 456 : THE PALEONTOLOGY OF MINNESOTA. [Platystrophia biforata. with minute granules radially and concentrically arranged, which when worn away presents a punctate exterior]. In the interior of the ventral valve a prominent hinge tooth exists on each side of the fissure [delthyrium] and is supported by strong dental plates, which enclose an elongated, oval, raised [in America, depressed, with an elevated outer margin] muscular cavity of moderate dimensions. In the interior of the dorsal valve no prominent cardinal process is observable, but two short brachial processes deviate from the extremity of the umbonal beak and on the outer side of these are situated the hinge sockets. The quadruple muscle forms four very distinct cavities, strongly margined and divided longitudinally and transversely by prominent cross-like ridges.’ These adductor scars are not nearly as well defined in American examples. | The writers regret their inability to secure very young specimens of this species for the purpose of determining the ancestors or line of development, In several immature individuals it has been observed that in the early nealogic stage the beaks are strongly elevated, probably erect, and each has a very large open delthyrium, surface smooth at first, but gradually developing eight plications and a mesial sinus in each valve. The sinus in the dorsal valve is bounded by two elevations, which become plications, and between them is soon developed a single costa which imme- diately bifurcates. The four plications increase in strength and become strongly elevated as they proceed to the anterior margin, producing the conspicuous fold of this valve. This widely distributed and protean species has its beginning, in North America, in the Chazy group, and is found in all the geological horizons upwards and into the Niagara formation. The earliest individuals are small in size and have but few and simple costz. Such specimens are found in the Cincinnati group around Cincinnati, Ohio, and are probably to be regarded as the young of P. biforata, or of the various forms occurring there and designated by varietal names. In the Ohio valley it attains its maximum in number of individuals, variation and size. In succeeding horizons it becomes less numerous and assumes characters somewhat ancestral. Adult individuals, occurring at a given horizon and locality, will be found to be fairly constant. However, in younger or older rocks, variations are continually taking place, and if specimens are gathered promiscuously from various horizons at a locality in which the shells are common, it will seem as if there were no con- stancy whatever in the species. While in a restricted region there is considerable permanence in shape and number of cost, in the same geological formation other variable characters sufficiently fixed for specific use are wanting. The species is to be regarded as very persistent and capable of readily adapting itself to changes of environment. Among the Brachiopoda such forms appear to be long lived. Others BRACHIOPODA. 457 Platystrophia biforata. ] equally protean are Leptena rhomboidalis, which extends from the Trenton into the Waverly, i. e., from the Lower Silurian to the base of the Carboniferous; Atrypa reticularis, extending throughout the Silurian and Devonian; Orthis testudinaria, from the Chazy to the top of the Lower Silurian; Plectambonites sericea, from the Trenton to the Clinton, i. e., from the Lower Silurian to the Silurian. The references treating strictly of the large and globose variety /ynz,* as defined by Meek,** are not given in the above synonomy, since that variety is regarded as amply distinct for easy recognition. It is not known to occur in the northwest. M. de Verneuil, in a foot note appended to the description of Spirifer sheppardi Castelnau, states that it is identical with Spirifer lynx Hichwald. The above descrip- tion and figures haye been studied by the writers, who find them to agree with examples here referred to P. biforata. If desirable to separate American specimens under another specific term, because they have, as a rule, a less number of cost in the sinus and fold than European examples of P. biforata, the name given by Castel- nau will have precedence. Platystrophia biforata is sparingly found near the top of the Trenton shales and becomes one of the characteristic fossils of the Galena shales in Minnesota. Nearly all the specimens seen have three plications in the sinus, with four on the fold, while an individual is rarely found with one more or one less. In other regions, the number in the sinus is also usually three, while occasionally only one, five, or even six are developed. Commonly there are from twelve to sixteen cost on each side of the fold and sinus. More rarely a specimen is found with ten, while several immature individuals have only from five to seven. Some of the plications are seen to terminate along the cardinal area, and since increase in number of costz very rarely takes place on the lateral slopes by bifurcation or otherwise, new ones may be added along the postero-lateral margins as the length of the hinge is increased. Formation and locality—Chazy group near Montreal, Canada. Common in the Trenton of New York, Canada, Kentucky, Tennessee, and rare in this horizon in the northwest. In the lower portion of the Galena formation it is common at many localities in Goodhue, Olmsted and Fillmore counties, Min- nesota; Decorah and Dubuque, lowa; Neenah and Oshkosh, Wisconsin, and, according to Castelnau, at the mouth of Menominee river, Green Bay. In the Cincinnati group of the Ohio valley; Nashville, Ten- nessee; Iron Ridge, Wisconsin; Graf, Iowa, and Silver City, New Mexico. In the Clintun and Niagara formations of Ohio, New York, Canada and Anticosti. It is also a common fossil in the Lower Silurian and Silurian in England, Scotland, Ireland, Gotland, Scandinavia, Oeland and Russia. Collectors.—Miss Cora E, Goode, Dr. Sandberg, W. H. Scofield, A. D. Meeds, HE. O. Ulrich and the writers. Mus. Rey. Nos. 2290, 4948, 5307, 5862, 7816-7828. *Terebratula lynx Bichwald. Skizze von Podolis, p. 202, 1830. **Pal, Ohio, vol. i, p. 114, figs. la-le, 1872. 458 THE PALEONTOLOGY OF MINNESOTA. (Platystrophia biforata, var. crassa. PLATYSTROPHIA BIFORATA, Var. CRASSA James. PLATE, XXXIII, FIGS. 53—54. 1873. Var. 3. Orthis (Platystrophia) dentata ?? MEEK (non PANDER). Paleontology of Ohio, vol. i, p. 117, pl. x, fig. 3. 1874. Orthis (Platystrophia) crassa JAMES (non LINDSTROM). Cincinnati Quarterly Journal of Science, vol. i, p. 20. 1875. Orthis dentata MILLER. Ibidem, vol. ii, p. 27. 1889. Orthis centrosa MILLER. North American Geology and Paleontology, p. 356. 1892. Platystrophia crassa HALL. Paleontology of New York, vol. viii, pt. i, pp. 223. This variety can be distinguished readily by its short hinge-line, causing the shell to be as wide as long, and its very gibbous valves. This species occurs sparingly in the Hudson River group at Spring Valley, Minnesota, and differs from those found at Cincinnati, Ohio, in having about three more much less elevated cost on each side of the fold and sinus. The muscular scars and other interior characters are more defined than in southern specimens. Since this variety is now referred to the genus Platystrophia, the name crassa James will not confilet with Orthis crassa Lindstrém, 1860.* The latter is said to be related to O. elegantula Dalman, and is therefore referable to Prof. Hall’s subgenus « Dalmanella. Mus. Reg. No. 5543. Order THLOTREMATA, Beecher. Family RHYNCHONELLIDA, Gray. Genus RHYNCHOTREMA, Hall. 1860. Rhynchotrema, HALL. ‘Thirteenth Report, New York State Cabinet of Natural History, p. 68, 1883. Rhynchotrema, ee Ese ae Indica, ser. xiii, vol. i, p. 410. Rhynchonella is an extensive genus, if all the species are admitted that are currently referred to it. It then has its beginning at the base of the Lower Silurian, continues through all the subsequent ages, and is represented at present by five living species. Several names have been proposed by authors for the earlier forms, but none of them have come into general use. Rhynchotrema will be employed for those early rhynchonelloid species having a prominent cardinal process between the crural plates of the dorsal valve. This process is very well developed in all Lower Silurian species of so-called Rhynchonella of which the interior has been examined. *Gotland’s Brachiopoden, p. 396, 1860, Also Davidson's Mono, British Sil. Brach., p. 218, pl. XXvut, figs. 17-19, BRACHIOPODA. 459 Rhynchotrema ainsliei. ] Ruyncnotrema arnsurer N. H. Winchell. PLATE XXXIV, FIGS. 1—8. 1886. Rhynchonella ainsliei N. H. WINCHELL. Fourteenth Annual Report of the Geological and Natural History Survey of Minnesota, p. 315, pl. , figs. 5, 6. This species has the essential characters of R. inequivalvis, therefore a detailed description will not be necessary. It differs from the latter in being usually larger, more transverse, and in having from twenty-eight to thirty-four plications, with six to eight on the fold, and five to seven on the sinus, while R. inequivalvis has from sixteen to twenty-two plications, with four to five on the fold. Compared with Rhynchonella altilis Hall* of the Chazy group of New York, Rhynchotrema ainslier is seen to be more transverse, has a more prominent fold and sinus, is less globose, and on the average has a few more plications. Formation and locality.—Restricted to the lower portion of the Trenton shales, where it is common at Minneapolis, Cannon Falls, Lanesboro, Fountain, Chatfield and Preston, Minnesota; Decorah and McGregor, Iowa. Collectors.—C. N. Ainslie, C. L. Herrick, W. H. Scofield, J. C. Kassube and the writers. Mus. Reg. Nos. 324, 326, 734, 4031, 4938, 4974, 5480, 5489, 5492, 5498, 5505, 5512, 5517, 5521, 7917, “8204-8207. RHYNCHOTREMA INZQUIVALVIS Castelnau. PLATE XXXIV, FIGS. 9—25. (843. Spiriferincequivalvis CASTELNAU. Essaisur le Syst?me Silurien de l’Amérique Septentrionale, p. 40, pl. xrv, fig. 8. 1847. Atrypa increbescens (partim) HALL. Paleontology of New York, vol. i, pp. 146, 289, pl. xxxu1, figs. 13a-13h; ? pl. LX XIX. fig. 6. 1856. Rhynchonella increbescens (partim) Burnes. Canadian Naturalist and Geologist, vol. i, p. 207, figs.. 11-14. . 1863. Rhynchonella increbescens BILLINGS. Geology of Canada, p. 18, fig. 153. 1875. Trematospira (?) quadriplicata Mi~tLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 60, figs. 6, 7. 1889. Rhynchotreta quadriplicata MILLER. North American Geology and Paleontology, p. 370. 1889. Rhynchonella increbescens NETTELROTH. Kentucky Fossil Shells, p. 83, pl. XXxXrv, figs. 26-29. 1892. Rhynchonella minnesotensis SARDESON. Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 333, pl. rv, figs. 21-23. Compare Atrypa subtrigonalis HALL. Paleontology of New York, vol. i, p. 145, pl. xxXII, figs. 12a-12c, 1847. The original description of R. increbescens was drawn up from specimens now referred to that species and to R. capax Conrad. That by Castelnau is not accessible at the present time. The following description is based on material derived from Minnesota, Kentucky and New York: Shell small, varying from narrow to broadly subtriangular in outline, smooth in the nepionic stage, depressed-convex during the nealogic period, and becoming more globose in ephebolic and geratologic growth; posterior lateral margins straight or somewhat convex, rounding rapidly into the sinuous anterior edge. Surface with prominent subangular plications, from sixteen to twenty-two on each valve, with from three to five on the fold, and two to four in *Pal. N. Y., vol. i, p. 323, pl. 1vbis, figs. 91-9d. 460 THE PALEONTOLOGY OF MINNESOTA. |Rhynchotrema inwquivalvis. ‘ the sinus; commonly, however, the number is seventeen or eighteen, four and three, respectively; in Kentucky specimens the tendency is to have fewer plications, there being from thirteen to eighteen on each valve, all crossed by exceedingly delicate concentric zigzag lines, sometimes subimbricating and conspicuous over the anterior half of the shell. Ventral valve strongly convex in the umbonal region and nearly flat on each side of the deep mesial sinus, sloping more or less abruptly laterally and often angular near the anterior margin; mesial sinus originating on the umbo, often profound anteriorly, with abrupt sides. Beak more or less incurved and always elevated beyond the umbo of the dorsal valve, with a narrow delthyrium partially closed by deltidial plates, which grow out from the walls of the former and, as far as observed, do not join medially. Hinge teeth prominent and supported by thin, short, dental plates. Muscular area much as in RF. capaz, except that in the present species it is very shallow, owing to the shells not being thickened as in R. capaz. Dorsal valve more convex than the other, with a mesial fold more or less strongly elevated anteriorly, beginning at the apex of the shell as a slight depression. Beak projecting into the delthyrium of the ventral valve. Crural plates large, sepa- rated medially by a depression which is partly occupied by a linear cardinal process strongly curved inward and upward, converging proximally and joining the angular median septum, which terminates at about the center of the valve on the crest of a plication; at the base of the crural plates and separated by the septum are two pairs of adductor scars, the anterior ones being the larger; dental sockets deep, situated lateral to the crural plates. The variations in this species are numerous, yet are never such as to be of value to the geologist, with one exception, which is described below as variety minnesotensis. R. inequivalvis has. often been considered to merge into FR. capax; this, however, is not known to occur anywhere in the Trenton formation, nor do the specimens of the - Hudson River group, in their younger stages, look exactly like adult R. inequivalvis. The figures given of the two species readily show the differences between them. In the middle beds of the Trenton limestone a number of free and very well preserved specimens, collected by Mr. Ulrich, have from twelve to fourteen plications on each valve, and are globose and smaller than is usual for this species. Similar but larger shells also occur rarely in the shales above. These specimens approach Rhynchonella orientalis of Billings,* from the Chazy group, but differ from it in having three or four more plications, and none of them has the straight, lateral outline shown in the second series of his figures. This is probably the form to which Mr. Sardeson has given the name R. minnesotensis, *Canadian Nat. and Geol., vol. iv, p. 443, 1859. BRACHIOPODA. 461 riety laticostata.] This species is known in America as Rhynchonella increbescens Hall, but unfortun- ately it must give way to R. inequivalvis, a name defined and illustrated four years earlier by Castelnau. The latter obtained his specimens from the “ Magnesian lime- stone, Drummond’s island.”+ Of the Trenton brachiopods, this is the most persistent and serves as a good marker of this formation. Associated with Orthis subcequata, it at once establishes the outcrop as of Trenton age. Formation and locality.—In the upper two-thirds of the Trenton limestone at Minneapolis, Minne- sota. Very common in the Trenton shales at Minneapolis, St. Paul, Cannon Falls, Chatfield, Lanesboro, Fountain, Eyota, Preston and near Caledonia, Minnesota; Decorah and McGregor, Iowa. Also common in the lower portion of. the Galena in Goodhue and Fillmore counties, Minnesota. In the ‘‘ Lower Blue beds” at Janesville, Beloit and Mineral Point, Wisconsin. In the Trenton at Dixon, Illinois; Auburn, Lincoln county, Missouri; Frankfort, Danville and Lexington, Kentucky; Nashville and elsewhere in Tennessee; Middleville, Trenton Falls, Watertown and other places in New York: Ottawa, Canada, and Drummond’s island. In the Galena at Oshkosh and Neenah, Wisconsin. ‘Two specimens have also been collected by one of the writers in the Hudson River group at Savannah, Illinois. Collectors——Miss C. L. Seymour, C. L. Herrick, J.C. Kassube, U.S. Grant, H. V. Winchell, W. H. Scofield, E, O. Ulrich and the writers. Mus. Reg. Nos. 266, 323, 328, 331, 370, 382, 650, 3493, 3516, 3517, 4053, 4925, 4933, 4941, 4999, 5128, 5473-5476, 5478, 5479, 5482, 5484, 5488, 5490, 5491, 5493, 5496, 5497, 5506, 5508, 5509, 5513, 5515, 5516, 5518, 5519, 5522, 5852, 5858, 5583, 6486, 6764, 6777, 6790, 6793, 6799, 6800, 7918, 8209-8218. Variety LaticostatTa W. and SV. PLATE XXXIV, FIGS. 26—29. 1892, Aprill. Rhynchotrema inceequivalvis, var. laticostata W. and S. American Geologist, vol. ix, 1892, April 9. Rhynchonella Se ape Bulletin of the Minnesota Academy of Natural Sciences, vol. iii, p. 333, pl. Iv, figs. 19-20. In the lower portion of the Galena south of Cannon Falls Rf. inwquivalvis often attains a far greater width than is usual for the species. The four plications of the fold are closely arranged, while the five or six on the side are spread out and are therefore larger than usual. These shells, if found alone, would be regarded at once as a distinct species. Their development begins in the lowest portion of the Galena shales, where specimens are sometimes picked up at St. Paul. However, it is not until this species is found in association with Clitambonites diversa Shaler that the variety becomes common and attracts attention. In the Trenton of New York and Kentucky an occasional specimen is found which approaches vay. laticostata, but none of them is so strongly transverse as Minnesota individuals. Collectors.—W. H. Scofield and the writers. Mus. Reg. No. 8219. *There is probably a slight mistake in referring this species to the **Magnesian limestone” of Drummond’s island, which belongs to the Upper Silurian. That limestone constitutes most of the island, and is not likely to hold its fossils in as éntire and perfect a condition as the specimen figured by Castelnau, However, there is a low exposure of the Lower Silurian along the north shore, rising about eighteen feet above the water, and these beds probably furnished the specimens deseribed by Castelnau. 462 THE PALEONTOLOGY OF MINNESOTA. {Rhynchotrema capax RHYNCHOTREMA CAPAX Conrad, sp. PLATE XXXIV, FIGS. 30—34. 1842. Atrypa capaw CONRAD, Journal of the Academy of Natural Sciences of Philadelphia, vol. viii, p. 264, pl. x1v, fig. 21. 1847. Atrypa inerebescens (partim) HALL. Paleontology of New York, vol. i, p. 16, pl. XX XIII, figs. 138i, 18k-13y. 1856. Atrypa increbescens (partim) BmLLiNes. Candian Naturalist and Geologist, vol. i, p. 207, figs. 15, 16. 1860. Atrypa increbescens HALL (not 1847). Thirteenth Report, New York State Cabinet of Natural History, p. 66, figs. 6, 7, 9-11. 1862. Rhynchonella increbescens (partim) HALL. Geology of Wisconsin, vol. i, p. 55, figs. 5-7. 1863. Rhynchonella capax BILLINGS. Geology of Canada, p. 21], fig. 213. 1873. -Rhynchonella capaxw MEEK. Paleontology of Ohio, vol. i. p. 128, pl. Xt, fig. 2. 1875. Rhynchonella capax MILLER. Cincinnati Quarterly Journal of Science, vol. ii, p. 17. 1880. Rhynchonella capax Wuirr. Second Annual Report, Indiana Bureau of Statistics and Geology, p. 489, pl. 1, figs. 9-11. 1881. Rhynchonella capax WuitE. Tenth Report of the State Geologist of Indiana, p. 121, pl. 1, figs. 9-11. 1882. Rhynchonella capax WHITFIELD. Geology of Wisconsin, vol. iv, p. 263, pl. xm, figs. 26, 27. Description: “Shell attaining about a medium size, varying with age from com- pressed subtrigonal to subglobose, old examples being often more convex than their diameter in any other direction; posterior lateral margins somewhat straightened and converging to the beaks at about a right angle in young shells, but becoming more rounded in the adult; lateral margins rounding to the front, which is more or less distinctly sinuous, or nearly straight in the middle. “Dorsal valve generally a little more convex than the other, most prominent in the middle and rounding abruptly or sloping more gently from the central region in all directions; the more elevated part forming anteriorly a depressed mesial ridge that is nearly flat and occupied by four plications on top, and rarely continues two- thirds of the way to the strongly incurved beak, while on young or compressed indi- viduals it is faintly marked even anteriorly; lateral slopes each occupied by four to seven or eight simple angular plications.” Interior with the apex much thickened and converging anteriorly into a prominent subangular median septum, which extends about half way to the front margin; bases of the crural processes prominent and drawn out into slender inwardly and upwardly curving hooks, between which there is a thin, but often strongly elevated, cardinal process, while on the outside of the former are the large dental cavities; on each side of the septum in the posterior half are two pairs of deeply excavated adductor scars, the anterior pair being the larger. “Ventral valve with its beak abruptly pointed and very strongly incurved upon that of the other valve in adult shells, but less distinctly curved and showing a small BRACHIOPODA. 463 Rhynchotrema capax.] opening under its apex [for the protrusion of the pedicle; it is formed by the deltidial plates, which grew from the walls of the delthyrium and joined medially, leaving an oval or circular aperture apically] in young examples; mesial sinus deep and well defined in gibbous specimens and less so in the young and more compressed forms, never quite reaching the front of the beak and always having three simple [some- times four], rather angular plications in the bottom that extend, like the others, to the apex of the beak in well preserved specimens; lateral slopes each occupied by from five to seven simple plications.” Interior with prominent hinge teeth, supported, according to the age of the specimen, by more or less thickened dental plates which join the outer elevated margin of the deeply excavated pear-shaped muscular area. Posterior to the center of this area there is, in old examples, a deep, elongate depres- sion containing the adductor scars, and surrounding these are the large pear-shaped diductors, the adjustors being placed postero-laterally to the latter. Posterior to, and above the muscular area, and between the hinge teeth in old or very obese examples, there is a rather deep rostral cavity, which seems to have been largely produced by the apex of the dorsal valve having been forced in that direction by anterior shell growth. In Wisconsin examples this cavity is often crossed by the coalesced, concave deltidial plates, leaving under it a narrow pasage for the peduncle to be extruded through the umbo of the valve. “Entire surface of both valves marked by numerous very regular, strongly zigzag, prominent, sublaminar marks of growth, that become nearly or quite obsolete, some- times on old examples.” (Meek, op. cit.) Obese specimens of this species are usually found with the apex of the ventral valve more or less worn away. This is nearly always ascribed to imperfect preser- vation, or due to weathering. Ohio specimens in which the delicate, sublaminar growth lines are well preserved also have the apex more or less broken. The writers, therefore, conclude that, as the pedicle opening was encroached upon by the dorsal umbo, owing to the shell becoming more convex with age, the peduncle was forced back through the beak of the ventral valve. Sometimes portions of the entire beak are worn away from the same cause. This condition is also seen in many species of both fossil and recent terebratuloids and may be due to convexity of the valves or to shortness of the peduncle. R. capax is often confounded with R. increbescens—R. invquivalvis Castelnau, but the larger size of the former, together with the greater convexity and thickness of the valves, will readily separate it from the latter. Even the young of R. capax can be distinguished from the adult of R. inequivalvis by the obsolete fold and sinus, fewer and larger plications, greater transversity and more prominent subimbricating growth lines. 464 THE PALEONTOLOGY OF MINNESOTA. {Rhynchonella (?) anticastiensis. Formation and locality.—A very characteristic and common species of the upper portion of the Hudson River group; a few specimens have also been secured from the upper portion of the Galena, which as far as can be determined, are referable to this species. In the Hudson River group at Spring Valley and Granger, Minnesota; Graf, Iowa; Iron Ridge, Stockbridge and near Clifton, Wisconsin; Wilmington, Illinois; near Cape Girardeau, Missouri; Ohio; Indiana; Kentucky, and Anticosti. In the Galena near Cannon Falls and near Rochester, Minnesota. Collectors.—John Kleckler, M. W. Harrington, W. H. Scofield and the writers. Also in the collection of Dr. C. H. Robbins, of Wykoff, Minnesota. Mus. Reg. No. 177, 4092, 4095, 5547, 8196-8199. RHYNCHONELLA (?) anticostieNsiIs billings. x Fig. 34. Rhynchonella anticostiensis Billings. a, b, c, different views of aspecimen. From ‘‘ Paleozoic fossils of Canada.” p. 142. 1862. Rhynchonella anticostiensis BILLINGS. Paleozoic Fossils, vol. i, p. 142, fig. 119A-C. 1863. Rhynchonella anticostiensis BILLINGS. Geology of Canada, p. 211, fig. 212. Compare with Rhynchonella argenturbica WHITE. Report of the U. S. Geological and Geographical Survey west of the 100th Meridian, vol. iv, p. 75, pl. Iv, fig. 12. Original description : ““Subpentagonal; apical angle about 80°; side nearly straight or slightly convex for rather more than half the length from the beak, then curving to the edge of the mesial sinus; front nearly straight for the breadth of the sinus; side view oblong; front, dorsal and ventral sides nearly straight; umbo of dorsal valve abruptly curved in to the base of the beak of the ventral valve, which is conical, erect and scarcely incurved. Ventral valve with a deep mesial sinus, becoming obsolete at two-thirds the length from the base; dorsal valve with a strong mesial elevation which, on approaching the umbo, disappears and is succeeded by a scarcely perceptible sinus, which continues to the summit. Surface with eighteen or twenty radiating angular ridges, crossed by close zigzag imbricating strize; three ribs in the ventral sinus and four on the dorsal mesial elevation.” The more or less erect beak of the ventral valve, and the conspicuous deltidial plates of R. anticostiensis, remind one much of species of Rhynchotreta Hall. This form is distinguished from R. neenah Whitfield by its greater triangular outline and in the four continuous plications of the less elevated median fold. Formation and locality.—Common in the upper beds of the Hudson River group at Wilmington and Savannah, Illinois; Graf, lowa; Wisconsin, and English Head, Anticosti. Collector.—C. Schuchert. Mus. Reg. Nos. 8201-8203. he. BRACHIOPODA. 465 Rhynchonnella (?) neenah. RHYNCHONELLA (?) NEENAH Whitfield PLATE XXXIV, FIGS, 35-37. 1882. Rhynchonella neenah WHITFIELD. Geology of Wisconsin, vol. iv, p. 265, pl. xm, figs. 19-22. This species is distinguished from R. anticostiensis in being more tumid and less triangular, while two of the four plications on the strongly elevated median fold usually become obsolete before reaching the anterior margin. Formation and locality.—Common in the upper portion of the Hudson River group at Iron Ridge and Clifton, Wisconsin; Savannah, Illinois, and probably also at Graf, Lowa. Collector.—C. Schuchert. Mus. Reg. No. 8146. Suborder HE LICOPHGMATA, Waagen. Family ATRYPID, Dall. Subfamily ZYGOSPIRIN AX, Waagen. Genus ZYGOSPIRA, Hall. 1847. Stenocisma, HALL (not CONRAD, 1839). Paleontology of New York, vol. i, p. 142. 1862. Zygospira, HALL. Fifteenth Report, N. Y. State Cabinet of Natural History, p. 154. 1862. Zygospira, BILLINGS. Canadian Naturalist and Geologist, vol. vii, p. 393. 1864. Stenocisma, MkEK and HAYDEN. Paleontology of the Upper Missouri, p. 16. 1867. Zygospira, HALL. Twentieth Report, N. Y. State Cabinet of Natural History, p. 267. 1868. Zygospira, MEEK. Geological Survey of Illinois, vol. iii, p. 377. 1882. Zygospira, DAVIDSON. Supplement to British Silurian Brachiopoda, p. 122. 1882. Anazyga, DAVIDSON. Ibidem, p. 128. Original description: “Shells bivalve, equilateral, inequivalve; surfaces plicate in the typical species; a sinus on the dorsal valve. Internal spires arranged some- what as in Atrypa, with a broad loop passing from, the outer limbs of the spiral band entirely across from side to side, near to or above the center and close to the inuer side of the dorsal valve.” (Hall, 1862, op. cit.) * It appears that Zygospira is the earliest known spire-bearing genus, and is there- fore very instructive. The apices of its spires are medio-dorsally directed, never laterally as in the Spiriferidw; this is the chief character by which the members of the family Atrypide can be distinguished from all other spire-bearing brachiopods. In the earliest species, Z. recurvirostra, the spiral cones are very loosely coiled, each with about three volutions, while the point of attachment of the connecting band is constantly near the base of the outer whorl. In Z. modesta there are four or five whorls to each spiral cone, but the point of attachment of the loop is variable. In Z. headi there are six whorls to a cone and the connecting band is in the posterior region. In Atrypa reticularis there is a very similar arrangement of the spirals, but —30 466 THE PALEONTOLOGY OF MINNESOTA. (Zygospira recurvirostra. with a still greater number of whorls to a cone, while the loop, which is no longer complete in mature individuals, is placed more posteriorly than in Z. headi, In the Devonian specimens of Atrypa reticularis the greatest number of revolutions to a spiral cone is attained. The evolution of the calcified brachial supports in. the family Atrypidw has gone on increasing in the number of whorls to x cone, the connecting band has progressed from the anterior to the posterior region, and all has kept pace with the gradual increase in size of the various species, from the Trenton to the Upper Devonian. The species of Zygospira are divisible into two groups—(1) the depressed-convex species with coarse striz in which the ventral valve is more or less carinated medi- ally, and (2) those with the valves globose and finely striated. Z. RECURVIROSTRA Hall—Trenton. Group I. Group II. . deflecta Hall, Trenton. . modesta (Say) Hall, Hudson River. . modesta, var. cincinnatiensis (James) Meek, Hudson River. kentuckiensis James, Hudson River. concentrica Ulrich, Hudson River. . paupera Billings, Anticosti. mica Billings,* Anticosti. . uphami W. and S., Galena. . erratica Hall, Hudson River. . anticostiensis Billings, Hudson River. . headi Billings, Hudson River. . headi, var. borealis Billings, Hudson River NNN NNNNN NNNSN ZYGOSPIRA RECURVIROSTRA Hall, sp. PLATE XXXIV, FIGS. 38—41. 1847. Atrypa recurvirostra HALL. Paleontology of New York, vol. i, p. 140, pl. xx xm, figs. 5a-5d. 1859. Rhynchonella ? recurvirostra HALL. Twelfth Report, N. Y. State Cabinet of Nat. Hist., p. 66. 1863. Khynchonella recurvirostra BILLINGS. Geology of Canada, p. 168, fig, 152. 1882. Anazyga recurvirostra DAvIDSON. Supplement to British Silurian Brachiopoda, p. 129. + Original description: “ Elliptical, somewhat ovoid, very symmetrical; breadth about one-fourth of an inch, length a little greater; dorsal [ventral] valve with the middle elevated, regularly convex on the sides, the beak extended and gracefully incurved over the beak of the ventral [dorsal] valve, which is regularly convex, with a slight longitudinal depression; surface of each valve marked by about twenty-four regular, simple, longitudinal striz, which continue entirely to the beak.” Minnesota examples’ of this species are usually a little shorter, and therefore rounder than eastern examples; otherwise they are identical. Compared with Z. modesta the latter is found to attain a larger size, is more transverse and never so gibbous as this species. The beak of the ventral valve is usually less incurved, while the strie bounding the sinus are more prominent. Of interior characters nothing is known beyond the spires and the connecting band. *RhynchotUg mica, Cat. Sil. Foss. Anticosti, p. 44, 1866. BRACHIOPODA. 467 Zygospira modesta.] In the nepionie stage of this form, in specimens about | mm. in length, the shell is depressed-convex without striations and plications, the beak of the ventral valve being erect and perforated by a large triangular delthyrium. This stage agrees essentially with the same age in species of Rhynchonella* and Rhynchotrema ineequi- valvis. In some individuals of 7%. recurvirostra the plications begin to develop along the anterior margin much earlier than in others. During the succeeding stages of growth the valves attain greater gibbosity, the delthyrium of the ventral valve becomes partially closed by the deltidial plates, the beak incurves over that of the dorsal valve and the striz become larger until a certain size is reached, after which new ones are introduced maintaining their equality. Z, uphami appears to be a descendant of 7%. recurvirostra. It differs in having attained a larger growth and greater convexity. The strizw, however, do not increase in size, but numerous new ones are added, so that 7. uphami appears more finely striated. Formation and locality.—This species occurs throughout the Trenton shales, but is very abundant near the base of the Galena shales in association with Pholidops trentonensis, var. minor, Orthis pectinella, var. sweeney?, and Rhyncholrema inequivalvis at Minneapolis, St. Paul, Cannon Falls and Fountain, Min- nesota. Also common in the Galena south of Cannon Falls and Kenyon, Minnesota, and at Oshkosh, Wisconsin. Near the top of the Trenton in association with Orthis borealis Billings, at Lexington, Dan- ville and Frankfort, Kentucky. Martinsburgh, Lowville and Middleville, New York; Ottawa, Canada. Collectors.—C. LL. Herrick, W. H. Scofield and the writers. Mus. Reg. Nos. 487, 489, 735, 767, 4069, 5477, 5511, 8220-8223. Zyeosrira MopDESTA (Say) Hall. PLATE XXXIV, FIGS. 42—44. 1847. Atrypa modesta HALL. Paleontology of New York, vol. i, p. 141, pl. xv, fig. 15. 1859. Genus ? modesta HALL. Twelfth Annual Report, N. Y. State Cabinet of Natural History, . p.66. ‘Related to Leptocelia.” 1860. U rt 7 q * iH Fi ‘ i ; @ ‘ ' ' 4 ’ ‘ , e ° ot ; + w - ‘ , ‘ y 4 a _ a ne * me i - . | 5 i - = ny _ _ - ox v ‘ —& fea - a at = may : i = k 2 Oe. a! i =. - =f P F i > - er 2 2 i + 7 ; i 4 * 1 AF _ Higss lstom 4. Figs. Figs. Figs. 11 to 17. Figs. 18 and 19. 18. 19. Figs. 20 to 23. 20 and 21. 22 and 23. Figs. 24 to 28. 24 and 25. 26. 27. 28. Figs. 29 to 31. 29 and 30. Bile BVO. Te 8 to 10. 8. 9. 10. PLATE XXX. PAGE. IN GUGASMAN CAT ENEN SIS cA Sr sciascinsaic cist see srencceaeeed eacenee ono Interior of the ventral valve from a gutta percha impression. g, umbonal scar; k, middle; 1, lateral scars; s, septum. Interior of the dorsal valve from a gutta percha impression. cr, crescent; h, central scars; j, anterior scars; ¢, transverse scars; other letters as in fig. 1. Profile of the type specimen from which the impressions of figs. 1 and 2 were made. The space between the dotted line and the natural cast shows the relative thickness of the shell. A portion of the exterior surface, x 5, to show the arrangement of the linear series of papillz on the concentric lines of growth. Near the top of the Galena limestone, near Hamilton, Minn. Minnesota Geological Survey collection. SCHIZAMBON! (2) DODGIL) De SDccenrce te an eee eet ee menses ome ae eins View of the ventral valve, showing the strongly lamellose concentric lines, spine bases and pedicle opening, x 2. A dorsal valve preserving some of the surface spines, x 2. Profile outline to show the relative convexity of valves and the projecting beak of the ventral valve, x 2. Upper Trenton at Sandy Hill, New York. Col- lection of C. Schuchert. SOHIZAMBON( (?) HOGRIUM GI Spot anita aaetota ee rte coisas eRe es The ventral valve, showing the submarginal beak and the pedicle opening. The dorsal valve of the same specimen in which the beak is marginal. Profile outline of the same specimen. p, pedicle valve. Middle beds of the Hudson River group, Cincinnati, Ohio. Collection of C. Schuchert. CETLAMBONTTES! DIVER SASS HAler SDEsec are ae iactemnice cece coe ene eee ne enics A dorsal view, showing the elevated area of the ventral valve, in which the del- tidium has been worn away, exposing the spondylium. (After Hall.) Ventral view of the same specimen. The distorted beak is not accidental, but a feature often developed in the species. (After Hall.) Interior of the ventral valve, showing the spondylium (sp) supported by a short septum (s). (After Hall.) Interior of the dorsal valve. cp, cardinal process; ad, adductor scars; 0, genital markings. Galena shales, near Cannon Falls, Minn. Collection of C. Schuchert. Interior of another dorsal valve in which the deltidium is preserved. The impres- sions of the vascular system are also shown on each side of the septum, and posterior to these are the genital markings. - A portion of fig. 15 in which the deltidium is broken away to show the muscular sears of the spondylium, x 2. An oblique view of the same specimen, to show the adjustor scars on the lateral limits of the spondylium, x 2. Galena shales, near Cannon Falls, Minn. Col- lection of W. H. Scofield. CLITAMBONITES DIVERSA, var. ALTISSIMA, 0. vat. Profile view, to show the great elevation of the ventral valve. Cardinal view of the same specimen. D, deltidium; ¥, foramen or pedicle open- ing. (After Hall.) Galena shales, south of Cannon Falls, Minn. Collection of C. Schuchert. SCENIDIUM PANTHONENSISL SATO ESOM Gy. .-.cate aocicticia te «nie c «ih slots deieenecaaee cle oloeace soece Ventral and cardinal views of a specimen, x 4. Trenton shales, near Cannon Falls, Minn. Collection of W. H. Scofield. Views of the exterior and interior of a dorsal valve. stone, Lebanon Tennessee. (After Hall.) Glade lime- ANASTROPHIA (?) SCOFIELDI, 0. Sp.........- Risiaticisteisia eieled eVeeneeree Views of the dorsal and ventral valves respectively. Profile view of the same specimen. Cardinal view of a distorted specimen, showing an area on the dorsal yalye, x 3. Profile outline, through the center of the shell, to show the extent of the spon- dylium, and the septum in the ventral valve, and the septal plates of the dorsal valve. Galena shales, near Cannon Falls, Minn, Minnesota Geological Survey collection. ANASTROBHEAS(>) REM EPLICAIIA Elaillletertycete et tersciee «cis: fifteen) 7 ert; i Dees -4) minis era TE ed , : ‘ t ) ono ! ahid tT etn i ne hen HF tot A oletal *) ween TE ey ty mere * “dil sh 7 , teh eT add Pe “7 apa iney ads | Sn : GRADTUTAS | Feiny I Td Noy lny feasiob é ts steve tl | fea to WE Sy Lmtd it 10 Tego lexan ep istiy) tLiam Kina tomo. and 2. Figs. 4and 5. 4. 5. Figs. 6and 7. 6. ths Fig. 16 16 and 17. Figs. Figs, 22 to 24. 22 and 23. 24. Figs. 26. 27 and 28. Figs. 35 to 37. 35 and 36. 37. s. 12 and 13. s.14 to 17. 14 and 15. 18) to, 21: 18 and 19. 20. 21. 25 to 29. PAN s. 30 and 31. s. 32 to 34. 32 and 33. 34. PLATE XXxXI. PAGE. STR OLHOME NAGS ED AUTUAU VV) GUIVC iiSiateseisieleratsletasclotetetialefevalstalayatan sketen-felaisteietstotelfetatetetenteeeia tote 390 Dorsal and profile views respectively of the same specimen. Interior of the ventral valve, to show the long median septum of this species. Trenton shales, St. Paul, Minn. Collection of C. Schuchert. STROPHOMENA RUGOSA (Rafinesque Ms.) Blainville..................eeeeeeeeeeees 390 Interior of the ventral valve. The septum of the muscular area does not extend to near the anterior margin, as in S. septata. Interior of the dorsal valve. Hudson River group, Oxford, Ohio. C. Schuchert. STROPHOMENA NEGLECTA, Var. ACUMA, MY VALs ««cisiec 2s = ale sice/seisaeielsje jac stelle 5 cl'= A view of the dorsal valve, to show the oblique wrinkling along the hinge line and distinct alternation of the strie. Profile outline of the same specimen. Collection of C. Schuchert. STROPHOMENA PLANODORSATA W. and S.. A dorsal view of the largest specimen seen, somewhat restored. The outline of smaller individuals is more like that of fig. 10. Profile outline of same specimen. Hudson River group, Spring Valley, Minn. University of Minnesota collection. Interior of a ventral valve referred to this species. ton, Illinois. Collection of C. Schuchert. STPROPHOME NAW SVIN CEDE TE Usl et cy rege etryeyetetstel state te tonelePalayatetalelecletaleetelclereielecelststelstelaletetsiststel A view of the dorsal valve of this species. (After Hall.) Lower Blue beds of Wisconsin. Collection of Hudson River group, Spring Valley, Minn. Hudson River group, Wilming- STROPHOMENA TRILOBATA Owen, Dorsal and profile views of a specimen showing the small, flat corrugated visceral disc, and the long median extension. Middle Galena, Old Concord, Minn. Col- lection of C. Schuchert. SRROLHOMEN AB HL UCLUOSAME IMI GS peieteerlatermietelertlslletstelapeietfelstelaietcaciatoleyetaichetelieteletcieiteets Dorsal and profile views of a specimen intended to show the strongly wrinkled visceral disc. The interior of a ventral and a dorsal valve respectively. Hudson River group, Spring Valley, Minn. Collection of C. Schuchert. STROPHOMENANSCORMETD Inv) 10 Cas aciereteey-telefarteteiiaielereetelersieities etal ceieieieiseietsterteier teeter Dorsal and profile views of a specimen of the usual size of this species. An interior of the dorsal valve. Minnesota Geological Survey collection. Interior of the ventral valve. Galena shales, near Cannon Falls, Minn. tion of W. H. Scofield. STOR HOMEN AWE MUA CUACVAY IVs CUT) ClitssivereretncrateeteleleloceleiepelTeeteel-ietereintstelclejoteinictelsieceeielatersteters View of the ventral valve, natural size, and a profile of the same specimen, x 2. View from the dorsal valve, x 2. Galena shales, near Cannon Falls, Minn. Col- lection of W. H. Scofield. RAFINESQUINA MINNESOTENSIS N. H. Winchell.... ....... 12... .cceceeceweeeees View of a natural cast, one of the type specimens, of the ventral valve as. pre- served in the Trenton limestone, Minneapolis, Minn. Minnesota Geological Survey collection. Profile view of a specimen from the Trenton shales, St. Paul, Minn. of C. Schuchert. ViALICUVAIN QUIASS Ata SAN CSO Ulneytetcyeyreteieteleve lee totenetersiaeteloielelevsteleteloletaatete lotsa etal -tstelstelereiteteteeets Dorsal and profile views respectively of a specimen of the ordinary size of this species as it occurs near the base of the Upper Buff beds at Mineral Point, Wis. Minnesota Geological Survey collection. Interior of the dorsal valve, showing the tive characteristic septa of this species. (After Hall.) RAFINESQUINA DELTOIDEA Conrad, sp. Views of a natural cast of the interior of the ventral valve and a profile of same. Middle Galena, Mantorville, Minn. Minnesota Geological Survey collection. RAFINESQUINA ALTERNATA (Conrad Ms.) Emmons, sp... A ventral and a profile view of this species as it occurs in the Galena shales in Goodhue county, Minn. Minnesota Geological Survey collection. Interior view of a thick dorsal vavle in which the various parts are strongly deyeloped. Trenton shales, St. Paul, Minn. Collection of W. H. Scofield. R. ALTERNATA, Val. LOXORHYTIS Meek, Var... secs ev eecnccccresiewsevseresscescs View of the ventral valve and a profile outline of the same specimen, ‘to show the great convexity and transversity of this variety. Collection of C. Schuchert. Interior of the dorsal valve. Hudson River group, Spring Valley, Minn. Min- nesota Geological Survey collection. Collec- Collection 388 393 394 398 399 401 403 403 404 CRIN RONDA aHIG ESORVENEOELNNE SD CAG ) Brachiopoda} iS VOL Ul Plate NXXT i Figs. 1 to 5. land 2. a 4. De Figs. 6 to 9. 6and 7. 8. 9. Figs. 10 to 12. 10. 11. 12. Figs. 13 to 17. 13, 14 and 15. 16 and 17. Figs. 18 to 23. 18, 19 and 20. 21. 22. 23. Figs, 24 to 30. 24 and 25. 26. 27, 28 and 29. 30. Figs. 31 to 34. 31. 32 and 33. 34. Figs. 35 to 38. 35 and 36. 37 and 38. Figs. 389 to 42. 39 and 40. 41 and 42. 42a. PLATEH XXXII. LEP TAN AC OMAR LOL Teal OWA GUS este eit nic settee cates lara vote te ele cicsleis sisvele ete e aisles Views of the ventral and dorsal valves respectively of an entire specimen, show- ing the zigzag surface ornamentation and the deflected anterior margin. Profile outline of the same specimen. Interior of the dorsal valve of a similar specimen. Interior of a ventral valve. logical Survey collection. Collection of C. Schuchert. Trenton shales, St. Paul, Minn, Minnesota Geo- LEPT#NA UNICOSTATA Meek and Worthen, Sp...-......0. secs seeeccee cece cecees An exterior view of the ventral valve and a profile outline of the same specimen. Minnesota Geological Survey collection. Interior of the ventral valve, showing the adductor and the elongate diductor muscle scars and the strongly tuberculose surface. Interior of the dorsal valve, which is much as in L. RHOMBOIDALIS, var. TENUT- STRIATA. Hudson River group, Spring Valley, Minn. Collection of C.Schuchert. PLECTAMBONUTES *SERICEAW SOW CLD Yay 8 Drreteteaversteterterctte erates attsycicte.steimene teierevelstersisrerslets A view from the dorsal valve of a specimen from the Hudson River group of Ohio. D, deltidium. (After Hall.) Interior of the dorsal valve of another specimen from the same locality. a, adductor muscle scars; ¢, crural plates; j, cardinal process; v, vascular impres- sions. (After Hall.) Interior of a ventral valve to show the crenulated hinge margin and the muscular scars. Hudson River group, Granger, Minn. Minnesota Geological Survey coliection. IPEEOTPAMBONTITES | GIBBOSA™ WNL Ce S sets ota siclevarotserniercpticloyotoleistaiavelelere centre ecreleremtie ee Ventral, dorsal and profile views respectively of an entire specimen, x 2. Dorsal and ventral valve interiors, drawn from gutta percha impressions made from natural casts. Middle Galena, near Cannon Falls, Mantorville and Old Concord, Minn. Minnesota Geological Survey collection. ORTHISPERICENARTAS COMPA Ce joaysetsereven clstareorere taiite siowian er nel wwinecs nesta oer Dorsal, ventral and profile views of a specimen wider than is common for the species. Minnesota Geological Survey collection. The interior of a well preserved dorsal valve. University of Minnesota collection. An interior of the ventral valve. E A cardinal view to show the small deltidia on both valves, and the chilidium of the dorsal valve, x 2. Trenton shales, Minneapolis, Minn. Collection of C. Schuchert. ORTHISE(DINOR THIS) DEREECTAY CONTAGs SPs weeccnies aidcabiemencebite «+s sisi cides cies Exterior and interior views of a ventral valve. (Fig. 24 after Hall.) The interior of a dorsal valve. (After Hall.) Trenton limestone, near Fountain, Minn. Ventral, dorsal and cardinal views of a rather thick specimen. (After Hall.) .Trenton limestone, Minneapolis, Minn. Collection of C. Schuchert. Profile outline of another specimen. Lower Blue beds, Janesville, Wis. sota Geological Survey collection. Minne- ORTHISy((DINORTHIS)) PECTINE LE Am MIN MONS neces. «1. sins oeeeiaesieccliiccecr =o The interior of the ventral valve of the type specimen of O. charlotte: Winchell. The outer margin of the shell is slightly broken. Trenton shales, Minneapolis, Minn. Minnesota Geological Survey collection. Dorsal valve and profile outline of another specimen. Cardinal view of the dorsal valve of a smaller specimen, to show the small del- tidium. Trenton shales, St. Paul, Minn. Collection of C. Schuchert. OF}(D)-PRCLINELEA, vary SWEBNEVI IN.yEls Winchell cw. . .sicuceacecmantce ets - 06 View from the dorsal valve and profile of same specimen. (Fig. 35 after Hall.) Interiors of the dorsa] and ventral valves. (After Hall.) Trenton shales, St. Paul, Minn. Collection of C. Schuchert. ORTH (DINOR THIS) pMERDSL Wry ANG Suyrettelore otetatoreieloraler-icielsistster-il-iarenietetst-reeneeiciastee e Dorsal and cardinal views of a specimen in which the strie are separated more than is usual. Ventral and profile views of a larger specimen. Cardinal view. Collection of W. H. Scofield. Galena shales, Kenyon, Minn. 411 414 416 418 424 426 Figs. 43 to 45. Figs. 46 to 50. 46, 47 and 48. 49. 50. Figs. 51 to 58. 51, 52 and 53. 54 and 55. 56 and 57. 58. Figs. 59 and 60. 59. 60. PAGE. OF (OB) anos VE CHOI IN MEIGS Socohta“codagans tose n500 oseenono sn odoar Dorsal, ventral and profile views of a very characteristic specimen of this variety. Galena shales, near Cannon Falls, Minn. Collection of C. Schuchert. ORTHIS (/DINOR THIS) (SUBQUAD RATA pal) Sis velar ate watt inters) ste eiclcisiels o\eiele sielelele)elelels Dorsal, ventral and profile views respectively of an entire specimen. Minnesota Geological Survey collection. An interior view of the ventral valve of a very old specimen in which the anterior margin is much thickened and reflexed. The vascular sinuses are abnormally developed, due to old age. Hudson River group, Spring Valley, Minn. Interior of a dorsal valve. (After Meek, Ohio Pal., vol. i.) OETHIS | (DINORTHIS)) PROAVITAMW A ANG Staves atiatsral ote tte) sereteneta a Miele|elelais elata\clets|«)ele/e\e/= Dorsal, ventral and profile views of an entire specimen. Collection of the Min- nesota Geological Survey. Dorsal and profile views of a large specimen. Hudson River group, Wilmington, Tlinois. Interior and profile views of a thick ventral valve. Hudson River group, Spring Valley, Minn. Interior of a dorsal valve. Hudson River group, Spring Valley, Minn. Collec- tion of C. Schuchert. RAFINESQUINA ALTERNATA, var. LOXORHYTIS MeeKk......5....+----+--20---eeee Perpendicular view of the hinge and muscular impressions of the specimen illus- trated on plate XXXII, fig. 37. Profile view of the same specimen. 428 431 407 GT. Cie ANDevA doh CS dees Us eO RSV NES O cA } Brachropoda \ Plate XXX VOL_II. PLATE XXXIII Figs. 1 to 4. Oras (HEBERTELLA?) BELLARUGOSA Conrad..... ...0...c.sceccceseceeseeeceoes land 2. Views of the exterior and interior of a large ventral valve. Galena shales, Minneola, Minn. Minnesota Geological Survey collection. sand 4. Exterior and interior views of a dorsal valve of the ordinary size. Galena limestone near Fountain, Mino. Collection of C. Schuchert. Wigshe5s 10st... ORRHIS (PERCTOR DAIS) PLICATELDA- Elalle os. .chavtssest nent = Corson fears aviseeaiee.s sles Ventral, dorsal and profile views respectively of an entire specimen. Galena shales, Kenyon, Minn. Collection of C. Schuchert. Figs. 8 to 13. ORTHIS (PLECTORTHIS) WHITFIELDI N. H. Winchell ......2.5... 020... .00ceeccee ee Sand 9. Ventral and dorsal views of one of the type specimens, a natural cast of the interior. f 10 and 11. A view of the ventral valve and profile outline of same of another type speci- men. Hudson River group, Spring Valley, Minn. Minnesota Geological Survey collection. 12. The interior of a small ventral valve. 13. A large ventral valve, abnormal in its growth. Hudson River group, Spring Valley, Minn. Minnesota Geological Survey collection. Figs. 14 to 16. Orrurs (DALMANELLA) HAMBURGENSIS? Walcott........-...c0eessscerereceseses 14 and 16. Ventral, profile and dorsal views respectively of an entire specimen referred with doubt to this species; 16a, fig. 16 x 2. Trenton shales near Fountain, Minn. Minnesota Geological Survey collection. Figs. 17 to 22: Orruis (DALMANELLA) TESTUDINARIA Dalman........--.0-0..20s-c0scsceeeeceee 17 and 18. Ventral and dorsal views of a specimen of this species from the Trenton shales, Minneapolis, Minn.; flig. 18 X 2. 19 and 20. Dorsal and profile outlines of the same specimen, x 2, Minnesota Geological Survey collection. : 21 and 22. Interior of the ventral and dorsal valves, x2. St. Paul, Minn. Collection of C. Schuchert. Figs. 23 and 24. O. (D.) TESTUDINARIA Var. EMACERATA Hall................00ccccceeseesecsaccece Two views, a dorsal and profile, of'a specimen referred to this variety. Hud- son River group, Spring Valley, Minn. Minnesota Geological Survey collection. ISS i20bO 29 -eel ON (Ds) LDESTUDUN AREA Veli) MTEL UVTI Oty reyejeteseleie elelersialaleleiereraleisielelalehctele) slelnis)ulaletstsleis\ctere 25 to 27. Ventral, dorsal and profile views respectively of an entire specimen. 28. Profile view of another somewhat thinner specimen. Minnesota Geological Sur- vey collection. 29, The interior of a dorsal valve in which the parts are strongly developed. Hudson River group near Spring Valley, Minn. Collection of C. Schuchert. Figs. 30 to 36. OrTHIS (DALMANELLA) SUBAQUATA CONTA ......2. ccc ceee cece cer eceec cee reece 30 to 32. Ventral, dorsal and profile views respectively of the type specimen of Orthis minneapolis Winchell. Trenton shales, Minneapolis, Minn. Minnesota Geo- logical Survey collection. 33, 34 and 34a. Dorsal, ventral and profile views of a specimen in which the fold and sinus are obsolete and the tubular strie conspicuous. Trenton shales, Minneapolis, Minn. Collection of C. Schuchert. 35. Interior of the ventral valve, x 2. (After Hall.) 36, Interior of the dorsal valve. (After Hall.) Base of the Upper Buff limestone, Minera! Point, Wisconsin. Figs. 37 to 39. O. (D.) SUB&QUATA var. CONRADI N. H. Winchell.............0-sseceeecceeseeees 37. View from the dorsal valve of a typical example of this variety, x 2. 38 and 39. Ventral and profile views of the same specimen of the natural size. Trenton limestone, Minneapolis, Minn. Minnesota Geological Survey collection. Higss40) to, 425 O2(D:) susp aAQuaTAnvar: PER VETAs CONTAC. - celle ainleleleeiciotl= alec clecn cis viele seals osc vie 40 and 41. Ventral and dorsal views of the type specimen of Orthis media Winchell. Base of Trenton shales, Minneapolis, Minn. Minnesota Geological Survey collection. 42. View from the dorsal valve of Conrad’s type specimen of Orthis perveta. (After Hall.) Base of Upper Buff beds at Mineral Point, Wisconsin. Wigs somtomto. OD) SUB AGUATA Var. GEBBOSA BIINZS)... 65 scciiemiincies «le vaio steicsitleveleinsiees + Dorsal, ventral and anterior views of a characteristic specimen of this variety. Trenton shales, Minneapolis, Minn, Collection of C Schuchert, 436 437 440 441 445 446 449 450 Figs. Figs. Figs. Figs. 46 and 47. 48 to 50. 51 to ‘54. 51 and 82. 53 and 54. 55 and 56. O: (DD SUB QUATA Var: CIRCULARIS N: H. Winchell ..5:..5..2. 0.0.22 scncevee selec Two views of the type specimen of Orthis circularis Winchell, a brachial and profile. Trenton shales, Oxford Mills, Goodhue county, Minn. Minnesota Geological Survey collection. ORTHIS (DALMANELLA) AM@NA N. H. Winchell .... 62.0020. oe cece cence cw lene Dorsal, profile and cardinal views of the type specimen. ?Galena limestone, Spring Valley, Minn. Minnesota Geological Survey collection. PLATYSTROPHIA BIFORATA SCHIOGHEIM, (Spill sss. clove clecls aielsleieid clo ele e+ cicisins sieve Ventral and cardinal views of a large specimen. Dorsal and profile views of a specimen of the ordinary size. Galena shales, Goodhue county, Minn. Collections of W. H. Scofield and C. Schuchert. PLATYSTROPHIA BIFORATA Var. CRASSA JaMES............ seas eecstecesceerscsears Ventral and profile views of a nearly globose specimen. Hudson River group, Spring Valley, Minn. Collection of C. Schuchert. 453 458 * (TUL Bogvnty DAR, EPS, SPC TE Vee hhh Ue tet, Brachiopoda| VOL. HI Plate XXXII WS 54, Airer’ a sling Yartig » LRT poh ary nae regi eS’. - r aad 4 2 a a Ste T hs ayy at Mad. WECEV yi aa pont ‘ann Ray peypa! Le Pita cis ener ctund : snob ata ae Ce USES 2] 4 q 407 B Fy v oR : a - > f : PDH ks 0" 4 \ le I ; q =p alia ; bea WU Ae ea uy, cy in ie Beier Tee St : ATGtEL ~seyte ’ et HSL Ee, rad gant ier frm. 4 Peal ata i te ‘our oad ha-waly slr hela LheTOd ab Fo ates ut HOEY PPA OS Sere ee ; fuel > Hts > vine et | 1 ooh SS al tig ewetat ays § > ark a ae oe i > [ee tattG eb atoloe often wireta a- ; r hha A F - Pale Dit Pieper hoe SBR See fear are er | eet Tie ‘ gical eee? PE ere Tae OT ehiveietee Way sA3 eset j ‘3 et wanes ols Lee opt ena ve abner eM Pe as e i yy “i 3 Sey é ’ ead Fone Wns Re , ’ e | 4 my : Vey é a PRR Bye camper ye ee) eae Meas ap hy . < Pes f ; f : sa 9 be. = eH fs ; . . i ; - oo = « = Ki : _ SCIENTIFIC IN DEX. ? concentrica, 466. : , Radia, mica, 466. deflecta, 468, 466. ; fect modesta, 467, 337*, 465-468. _ erratica, 469, 466. ee = var. _ cincinnatiensis, 466. _headi, 469, 465, 466. , * paupera, 466, var. anticostiensis, 469. : recurvirostra, 466, 155, 344, 465-468, 473. var. borealis, 466. uphami, 468, 334, 466-469. _kentuckiensis, 466, Zygospirine, 465. . - ad , 4 » 5 : x ‘ = = i o- - t > ” = —- sy z > ] y 2 “as 4 ae a ™ F - va Z ae x ae ae sist v « . ; cs ; ary ‘ oe pe Se Lee a Sat ecm 2 \ i f 4 It is A in ates mal a fl tu f Wi WA i ae Ul ai) J a! RY trait Vee liga (1 hi se a . Alte ty br y A We fi i i an 1X | i. ~ hig | fl mA Rall. Va ASIN PA GSN Ih Pa Sh SY AU LN CHEN PAU ROrallh NY SSS iss" LOM EIN Sal, \ WOM: NUH Seezze IRN | i Os < BONA ES is