FOR THE PEOPLE FOR EDVCATION FOR SCIENCE LIBRARY or THE AMERICAN MUSEUM OF NATURAL HISTORY ■s. C/5 m m u u <: w i H O w o < Natural Hisvokt oWvky o!f Illinois STATE LABORATORY OF NATURAL HISTORY S. A. Forbes, Director S"f 7 (7 THE FISHES OF ILLINOIS STEPHEN ALFRED FORBES, Ph.D., LL.D. AND ROBERT EARL RICHARDSON. A.M. PUBLISHED BY AUTHORITY OF THE STATE LEGISLATURE ILLINOIS PRINTING COMPANY DANVILLE, ILLINOIS /•2-fc aA^V, ***<> W. Contents PAGE Introduction xi The Topography and Hydrography of Illinois xv The Northwestern Unglaciated Area xvi The Areas of Iowan and Illinoisan Drift xvii The Area of the Wisconsin Drift xix The Unglaciated Southern Area xx The River Systems xx Rock River System xxi Rock River xxi Pecatonica River xxiv Kishwaukee River xxv Green River xxv The Northwestern Area xxvi Galena River xxvii Apple River xxvii Plum River xxvm The Mississippi Bluff Drainage xxviii Edwards River xxvm Pope Creek xxix Henderson River xxix Bear Creek xxix Big Creek xxix Cahokia River xxx Illinois River Svstem xxx Des Plaines River xxxi Kankakee River xxxin Iroquois River xxxv Illinois River xxxv Fox River xliv Vermilion River xlv Mackinaw River xlvi Spoon River xlvii Sangamon River xlviii Salt Creek xlix Crooked Creek xlix Apple Creek 1 Macoupin Creek li Kaskaskia River System H Kaskaskia River lii Shoal Creek liii Silver Creek liv Big Muddy River System liv IV FISHES OF ILLINOIS PAGE The Wabash System lvi Wabash River lvii Vermilion River lviii Little Vermilion River lix Embarras River lix Little Wabash River lx Saline River System lxii Cache River lxiii Big Bay Creek lxiv The Lake Michigan Drainage lxv On the General and Interior Distribution of Illinois Fishes lxvii The General Distribution lxviii The Interior Distribution lxxviii The Illinois Basin and the other Districts compared lxxxvi Relations of each District to all the others xciii The Fishes of Northern, Central, and Southern Illinois xcv Use of Localitv Maps xcviii Peculiarities of Distribution in the Lower Illinoisan Glaciation xcix Classification and Use of Ecological Data cii Fishes of the Ohio and of the Mississippi Drainage ciii Boundarv between Northern and Southern Species cv General Features of Ecological Distribution cv Ecological Table cix General Summary cxiv Maps I. -CIII., preceded by list. The Fisheries of Illinois cxvii Explanation of Terms used cxxii Glossary of Technical Terms cxxv Key to the Families of Illinois Fishes 1 Class Marsipobranchii 5 Order Hyperoartii 5 Family Petromyzonidae. Lampreys 5 Genus Ichthyomyzon Girard 9 I. concolor (Kirtland). Silvery Lamprey 9 Genus Lampetra Gray 11 L. wilderi Gage. Brook Lamprey 11 Class Pisces 13 ( )rder Selachostomi IS Family Polyodontidae. Paddle-fishes 15 Genus Polyodon Lacepede 16 P. spathula (Walbaum). Paddle-fish 16 Order Chondrostei 21 Family Acipenseridae. Sturgeons 21 I '.< mis Acipenser Linnaeus 24 A. rubicundus Le Sueur. Lake Sturgeon 24 Genus Scaphirhynchus Heckel 26 S. platorhynchus (Rafinesque). Shovel-nosed Sturgeon . 27 Genus Parascaphirhynchus F< irbes & Richardson 28 I', all. us Forbes & Richardson, White Sturgeon 28 ( >nler Rhomboganoidea 30 Family Lepisi isteidae. Garpikes 30 CONTENTS V PAGE Genus Lepisosteus Laeepede 31 L. osseus (Linnaeus'). Long-nosed Gar 31 L. platostomus Rafinesque. Short-nosed Gar 34 L. tristcechus (Bloch & Schneider). Alligator-gar 35 Order Cycloganoidea 37 Family Amiidae. Bowfins ■ 3 7 Genus Amia Linnaeus 38 A. calva Linnaeus. Dogfish 38 Order Isospondyli 42 Family Hiodontidae. Mooneyes 42 Genus Hiodon Le Sueur 43 H. alosoides (Rafinesque). Northern Mooneye 43 H. tergisus Le Sueur. Toothed Herring 44 Family Dorosomidae. Gizzard-shad 45 Genus Dorosoma Rafinesque 45 D. cepedianum (Le Sueur). Gizzard-shad 45 Family Clupeidae. Herrings 47 Genus Pomolobus Rafinesque 48 P. chrysochloris Rafinesque. Golden Shad 48 Genus Alosa Cuvier 49 A. ohiensis Evermann. Ohio Shad 49 Family Salmonidae. The Salmon Family 50 Genus Coregonus (Artedi) Linnaeus 51 C. clupeiformis (Mitchill). Common Whitefish 51 Genus Argyrosomus Agassiz 53 A. artedi (Le Sueur). Lake Herring 54 Genus Cristivomer Gill & Jordan 55 C. namaycush (Walbaum). Great Lake Trout 56 Order Apodes 58 Family Anguillidae. Eels 58 Genus Anguilla Shaw 59 A. chrysypa Rafinesque. American Eel 59 Order Eventognathi 6 1 Family Catostomidae. Suckers 61 Genus Cycleptus Rafinesque 65 C. elongatus (Le Sueur). Missouri Sucker 65 Genus Ictiobus Rafinesque 66 I. cyprinella (Cuvier & Valenciennes). Red-mouth Buffalo 68 I. urus (Agassiz). Mongrel Buffalo 70 I. bubalus (Rafinesque). Small-mouth Buffalo 72 Genus Carpiodes Rafinesque 74 ('. carpio (Rafinesque). Common River Carp 76 C. difformis Cope. Blunt-nosed River < 'arp 77 C. velifer (Rafinesque). Quillbat k 78 C. thompsoni Agassiz. Lake Carp 7') Genus Erimyzon Jordan 80 E. sucetta oblongtis (Mitchill). Chub-sucker 81 Genus Minytrema Jordan 82 M. melanops (Rafinesque). Spotted Sucker 83 Genus Catostomus Le Sueur 83 FISHES OF ILLINOIS PAGE C. catostomus (Forster). Long-nosed Sucker 84 C. commersonii (Lacepede). Common Sucker 85 C. nigricans Le Sueur. Hogsucker 86 Genus Moxostoma Rafinesque 88 M. anisurum (Rafinesque.) White-nosed Sucker 89 M. aureolum (Le Sueur). Common Red-horse 90 M. breviceps (Cope). Short-headed Red-horse 91 Genus Placopharynx Cope 92 P. duquesnei (Le Sueur) 93 Genus Lagochila Jordan & Brayton 94 Family Cvprinidae. The Minnows and the Carp 94 Genus Cyprinus (Artedi) Linnaeus 104 C. carpio Linnaeus. European Carp 104 Genus Campostoma Agassiz 110 C. anomalum (Rafinesque). Stone-roller 110 Genus Chrosomus Rafinesque 112 C. ervthrogaster Rafinesque. Red-bellied Dace 112 Genus Hybognathus Agassiz 114 H. nuchalis Agassiz. Silvery Minnow 114 H. nubila (Forbes) 116 Genus Pimephales Rafinesque 117 P. promelas Rafinesque. Black-head Minnow 117 P. notatus (Rafinesque). Blunt-nosed Minnow 119 Genus Semotilus Rafinesque 121 S. atromaculatus (Mitehill). Homed Dace 121 Genus Opsopceodus Hay 124 O. emiliae Hay '. 124 Genus Abramis Cuvier • 12 5 A. crvsoleueas (Mitehill). Golden Shiner 126 I '.. mis Cliola Girard 128 C. vigilax (Baird & Girard). Bullhead Minnow 128 Genus Notropis Rafinesque 130 N. anogenus Forbes 132 N. cayuga Meek 133 N. cayuga atrocaudalis Evermann 134 \. heterodon (Cope) 134 N. blennius (Girard). Straw-colored Minnow 137 N. phenacobius Forbes 138 \. gilberti Jordan & Meek 139 X. illecebrosus (Girard) ■ 140 N. hudsonius (De Witt Clinton). Spot-tailed Minnow . Ill X. lutrensis (Baird & Girard). Redfin 143 N. whipplii (Girard). Steel-colored Minnow 145 N. cornutus (.Mitehill). Common Shiner 147 X. pilsbryi Fowler 149 X. jejunus ( Forbes) ISO X. atherinoides Rafinesque. Shiner 151 X. rubrifrons (Cope) Rosy-faced Minnow 153 X. umbral ilis atripes (Jordan). Black fin 154 Genus Ericymba Cope 156 CONTENTS Vll PAGE E. buccata Cope. Silver-mouthed Minnow 156 Genus Phenacobius Cope 158 P. mirabilis (Girard). Sucker-mouthed Minnow 158 Genus Rhinichthys Agassiz 160 R. cataractae (Cuvier & Valenciennes). Long-nosed Dace 160 R. atronasus (Mitchill). Black-nosed Dace 162 Genus Hybopsis Agassiz 163 H. hyostomus (Gilbert) 163 H. dissimilis (Kirtland). Spotted Shiner 164 H. amblops (Rafinesque). Big-eyed Chub 165 H. storerianus (Kirtland). Storer's Chub 166 H. kentuckiensis (Rafinesque). River Chub 167 Genus Platygobio Gill 170 P. gracilis (Richardson). Flat-headed Chub 170 Order Nematognathi 172 Family Siluridae. Catfishes 172 Genus Ictalurus Rafinesque 177 I. furcatus (Le Sueur). Blue Cat 178 I. anguilla Evermann & Kendall 179 I. punctatus (Rafinesque). Channel-cat 180 Genus Ameiurus Rafinesque 183 A. lacustris (Walbaum). Catfish of the Lakes 184 A. natalis (Le Sueur). Yellow Bidlhead 185 A. nebulosus (Le Sueur). Common Bullhead 187 A. melas (Rafinesque). Black Bullhead 190 Genus Leptops Rafinesque 193 L. olivaris (Rafinesque). Mud-cat 193 Genus Noturus (Rafinesque) 194 N. flavus Rafinesque. Stonecat 194 Genus Schilbeodes Bleeker 196 S. gyrinus (Mitchill). Tadpole Cat 197 S. nocturnus (Jordan & Gilbert). Freckled Stonecat. ... 198 S. exilis (Nelson). Slender Stonecat 199 S. miurus (Jordan). Brindled Stonecat 200 Order Haplomi 202 Family Umbridae. Mudfishes 202 Genus Umbra (Kramer) Muller 203 U. limi (Kirtland). Mud-minnow 203 Family Esocidae. Pikes 205 Genus Esox (Artedi) Linnaeus 205 E. vermiculatus Le Sueur. Little Pickerel 206 E. lucius Linnaeus. Common Pike 207 E. masquinongy Mitchill. Mitskallunge 209 Family Poeciliidae. Killifishes 210 Genus Fundulus Lacepede 211 F. diaphanus menona (Jordan & Copeland). Menona Top- miunow 211 F. dispar (Agassiz) 212 F. notatus (Rafinesque). Top-minnow 213 Genus Gambusia Poey 215 Vlll FISHES OF ILLINOIS PAGE G. affinis (Baird & Girard). Viviparous Top-minnow . . 215 Family Amblyopsidae. Blindfishes 217 Genus Chologaster Agassiz 218 C. papilliferus Forbes. Spring Cave-fish 218 Order Acanthopteri 220 Family Gasterosteida?. Sticklebacks 221 Genus Eucalia Jordan 222 E. inconstans (Kirtland). Brook Stickleback 222 Genus Pygosteus Brevoort 224 P. pungitius (Linnaeus). A'ine-spined Stickleback 224 Family Percopsidas. Trout- perches 225 Genus Percopsis Agassiz 225 P. guttatus Agassiz. Trout-perch 225 Family Atherinidae. Silversides 226 Genus Labidesthes Cope 227 L. sicculus (Cope). Brook Silverside 227 Family Aphredoderidae. ['irate- perches 228 Genus Aphredoderus Le Sueur 229 A. sayanus (Gilliams). Pirate-perch 229 Family Elassomidae. Pigmy Sun fishes 231 Genus Elassoma Jordan 231 E. zonatum Jordan. Pigmy Sunfish 232 Family Centrarchidss. Sunfishes 232 Genus Pomoxis Rafinesque 237 P. annularis Rafinesque. White Crappie 238 P. sparoides (Lacepede). Black Crappie 240 Genus Centrarchus Cuvier & Valenciennes 241 C. macropterus (Lacepede). Round Sunfish 241 Genus Ambloplites Rafinesque 242 A. rupestris (Rafinesque). Rock Bass 243 Genus Chaenobryttus Gill 245 C. gulosus (Cuvier & Valenciennes). Warmouth Bass.. 245 Genus Lepomis Rafinesque 247 L. cyanellus Rafinesque. Blue-spotted Sunfish 248 L. ischyrus (Jordan & Nelson) 250 L. symmetricus Forbes 251 L. euryorus McKay 252 L. miniatus Jordan 253 L. megalotis (Rafinesque). Long-eared Sunfish 254 L. humilis (Girard). Orange-spotted Sunfish 255 L. pallidas (Mitchill). Bluegill 257 Genus Eupomotis Gill & Jordan 259 I-;, heros (Baird & Girard) 259 E. gibbosus (Linnaeus). Pumpkinseed 260 Genus Micropterus Lai epede 262 M- dolomieu Lacepede. Small-mouthed Black Bass 263 M. salmoides (Lacepede) Large-mouthed Black Bass. . . 267 Family Percidae. Pert lies 269 Genus Stizostedion Rafinesque 271 S. vitreum (Mifc hill). Wall eyed Pike 272 CONTENTS IX PACK S. canadense griseum (De Kay). Gray Pike 274 Genus Perca (Artedi) Linnaeus 275 P. flavescens (Mitchill). Yellow Penh 276 Subfamilv Etheostominae. Darters 278 Genus Percina Haldeman 281 P. caprodes (Rafinesque.) Log-perch 281 Genus Hadropterus Agassiz 283 H. evermanni Moenkhaus 284 H. phoxocephalus (Nelson) 285 H. aspro (Cope & Jordan). Black-sided Darter 286 H. ouachitas (Jordan & Gilbert) 288 H. evides (Jordan & Copeland) 288 H. seierus Swain 289 Genus Cottogaster Putnam 290 C. shumardi (Girard) 290 Genus Diplesion Rafinesque 291 D. blennioides (Rafinesque). Green-sided Darter 292 Genus Boleosoma De Kay 294 B. nigrum (Rafinesque). Johnny Darter 294 B. eamurum Forbes 298 Genus Crystallaria Jordan & Gilbert 300 C. asprella (Jordan) 300 Genus Ammocrypta Jordan 301 A. pellucida (Baird). Sand Darter 301 Genus Etheostoma Rafinesque 303 E. zonale (Cope). Banded Darter 304 E. eamurum (Cope). Blue-breasted Darter 306 E. iowas Jordan & Meek 306 E. jessiae (Jordan & Brayton) 307 E. eceruleum Storer. Rainbow Darter 309 E. obeyense Kirsch ill E. squamiceps Jordan 312 E. flabellare Rafinesque. Fan-tailed Darter 313 Genus Boleichthys Girard 315 B. fusiformis (Girard) 315 Genus Microperca Putnam 317 M. punctulata Putnam. Least Darter 317 Family Serranida?. Sea Bass 318 Genus Roccus Mitchill 319 R. chrysops (Rafinesque). White Bass 319 Genus Morone Mitchill 320 M. interrupta Gill. Yellow Bass 321 Family Sciaenidae. Drums 322 Genus Aplodinotus Rafinesque 323 A. grunniens Rafinesque. Fresh water Drum 323 Family Cottidas. Sculpins 325 Genus Cottus (Artedi) Linnaeus 326 C. ictalops (Rafinesque). Common Sculpin 326 C. ricei Nelson 227 Genus Uranidea De Kay 328 X FISHES OF ILLINOIS PAGE U. kumlienii Hoy 328 Order Anacanthini 330 Family Gadidae. Codfishes • 330 Genus Lota (Cuvier) Oken 330 L. maculosa (Le Sueur). Burbot 331 Selected Bibliography 333 Index 343 Introduction It is the purpose of the present volume to furnish to those inter- ested in Illinois fishes a reliable guide to a knowledge of the species, a careful account of their local and general distribution and of their re- lations to their environment, a correct idea of the function and relative importance of the different species in the general system of aquatic life, and a fairly full summary of their habits and utilities so far as these are now known. To this end the species have, with very few ex- ceptions, been described anew from the specimens of our collection, with due use, however, of descriptions already extant ; analytical keys have been made, adapted, or selected, with special reference to the Illinois species; and our data of geographical and local distribution and of ecological situation and relationship have been analyzed, to a considerable extent, by statistical methods. The collections and field observations of Illinois fishesupon which this report is based were begun by the senior author in 1876, and were continued by him and by a considerable list of assistants, at rather irregular intervals, to 1903. With the establishment of the Illinois Biological Station on the Illinois River at Havana in 1894, field work in ichthyology became more nearly continuous than had previously been possible. An especially interesting study was made at Havana during the winter and spring of 1898 and 1899 by Mr. Wallace Craig, an assistant of the State Laboratory, to whom was assigned the duty of making systematic collections at fixed points by the uniform use of identical apparatus at each, determining, counting, and recording all the species obtained in each situation. It was the object of this investigation to apply, in the field of ichthy- ology, the quantitative method which had been used with distin- guished success in the study of the plankton of the Illinois River and adjacent waters at the Havana Station. During the summer of 1899 field work was transferred to Meredosia with Mr. H. A. Surface in charge, and later it was taken up by Mr. Thomas Large at Mere- dosia and Ottawa, to which latter place the station equipment was transferred in 1901. Extensive wagon-trips were made from time to time through various parts of the state for a study of the fishes of the smaller streams, the most important of them in 1899 by Mr. Large, to whom we are indebted for the field determination of many of our specimens and for numerous descriptive notes on the waters and situations visited. XII FISHES OF ILLINOIS Valuable collections have sometimes been obtained, especially from western Illinois, by arrangement with high-school teachers, who have fished the streams of their neighborhoods in accordance with our instructions, and in consideration of our return of a named series of specimens to their schools. Our field apparatus consisted mainly of seines of various size and mesh, from the smallest and finest minnow seines to those long enough and deep enough for use in our largest rivers. For collec- tions from weedy ponds and from creeks, and especially from swift waters or from streams where a shore landing was difficult, we have i Ic] tended largely on the so-called "Baird seine," a close-meshed min- now seine of medium length with a wide-mouthed, deep, conical bag of netting in its center. Trammel-nets have been very serviceable in waters through which a seine could not be drawn, especially in those encumbered by brush or filled with water-plants. Set-nets or pound-nets of various size and mesh, both with and without wings, have brought us much material, especially of the larger and more abundant species. For our knowledge of these, however, we have depended largely upon an inspection of fish markets and an exam- ination of the catches of commercial fishermen, with whom we have, indeed, made frequent trips to their fishing grounds. More than 200,000 specimens of our ISO species have been thus collected and preserved, under aboLit 1,800 accessions numbers rep- resenting differences of date, location, or situation, and from more than 450 localities, fairly well distributed through ninety-three of the one hundred and two counties of the state. These collections bore, as a rule, permanent labels showing the date, place, and body of water from which they came, and, in the majority of cases, some pari iculars concerning the apparatus used and the more notable fea- tures of the situation. This has made possible a statistical analysis of Hi! data of relative abundance of the different species under varying conditions, geographical, local, ami ecological, and also of the fre- quencies of joint or associate occurrence of the various species, one with another, in each class of situation or in each place. The results of statistical comparisons of this kind have been used to some extent in Ihis report, especially in the chapter on geographical and ecolog ieal distribution, and in the detailed discussions of the leading fam- ilies, genera, and species. A knowledge of the food and feeding activities of fishes is funda- mental to any tan- understanding of their place and function in the ■ral system of life, and especialb lo any just appnvial ion of their importance to man. Unfortunately, our definite knowledge of this INTRODUCTION Xlll field is very limited, and for most of the statements made concerning the food, feeding habits, and alimentary structures of fishes, we have had to draw upon the papers of the senior author, published in vol- umes I. and II. of the Bulletin of the Illinois State Laboratory of Natural History, and based upon studies made between the years 1878 and 1888. In the details of the classification we have followed, with little variation, Jordan and Evermann's catalogue of "The Fishes of North and Middle America," published as Bulletin 47 of the U. S. National Museum, but our arrangement of orders and families is that proposed by Boulenger, in Volume VII. of the Cambridge Natural History, and followed in the main by Jordan in his "Guide to the Study of Fishes." It has not been our purpose to enter into the synonymy except so far as was necessary to connect the specific names here used with both the more general publications in this field and the more special papers on the fishes of Illinois. We have in all cases referred to the original description of the species, and have, with few exceptions, made reference also, using the abbreviations indicated, to the follow- ing books and articles: Gunther: Catalogue of the Fishes in the British Museum. (Abbre- viation, G.) Jordan and Gilbert: Svnopsis of the Fishes of North America, (J. & G.) Jordan: Manual of the Vertebrates of the Northern United States. 8th edition, 1888. (M. V.) Jordan and Evermann. The Fishes of North and Middle America. (J. & E.) Boulenger: Catalogue of the Ferciform Fishes in the British Museum. (B.) Nelson : A Partial Catalogue of the Fishes of Illinois. Bull. 111. State Lab. Xat. Hist., Vol. I., No. 1. (N.) Jordan: A Catalogue of the Fishes of Illinois. Bull. 111. State Lab. Nat. Hist., Vol. I., No. 2. (J.) Forbes: A Catalogue of the Native Fishes of Illinois. Rep. 111. State Fish Comm., 1884. (F.) Forbes: Various papers on the food of fishes. Bull. 111. State Lab. Nat. Hist., Vols. I. and II. (F. F.) Large: A List of the Native Fishes of Illinois, with Kevs. Rep. 111. State Fish Comm., 1900-02. (L.) Richardson: A Review of the Sunfishes of the current Genera Apo- motis, Lepomis, and Eupomotis, with particular Reference to the Species found in Illinois. Bull. 111. State Lab. Nat. Hist., Vol. VII., Art. III. (R.) Besides the assistants already mentioned, especial acknowlnlg- ments are due to Mr. H. Garman, assistant in the State Laboratory XIV FISHES OF ILLINOIS and collector of much of our material during the early years of the work ; to Mr. A. J. Woolman, who, in 1903, made and recorded meas- urements of many specimens of the commoner species, and who, by his studies of the osteology of the Catostomidce opened the way to improved generic definitions of Ictiobus and Carpiodes; and to Mrs. Lydia M. (Hart) Green and Miss Charlotte M. Pinkerton, who made, under the supervision of the field ichthyologists, the colored draw- ings by which this report is illustrated. Professor Frank Smith, Dr. C. A. Kofoid, Mr. C. A. Hart, Mr. J. E. Hallinen, and Mr. E. B. Forbes have, during their several periods of service on the State Lab- oratory staff, added considerably to our knowledge of the fishes of the state. It is impracticable to give the names of all outside the staff of the State Laboratory who have been, from time to time, of mate- rial assistance in the long course of this work, but this list of ac- knowledgments would be seriously deficient without particular men- tion of Dr. S. E. Meek, of the Field Museum, and Dr. Barton W. Evermann, of the U. S. Fish Commission, both of whom have been especially obliging in passing judgment on sets of specimens of dif- ficult determination, and in scrutinizing the tables of geographical distribution printed in the introductory part of this report. It is a pleasure to acknowledge also our indebtedness to a considerable number of careful and observant fishermen who have told us much of the habits and behavior of our best-known fishes. To Messrs. John A. Shulte, of Havana, J. P. Baur, of the U. S. fisheries sta- tion at Meredosia, David Yeck, of Meredosia, W. J. & H. L. Ash- lock, of Alton, and Miles Newberry, of Havana, we owe many facts concerning the life and economy of our fishes which we should not otherwise have obtained. More than to any other, the Director is indebted to Mr. R. E. Richardson — his colleague during three years in the preparation of this report — for indispensable service in the field, the laboratory, and the library, and especially for the accumulation and organiza- tion of material of all descriptions, for his critical study of the col- lections, all of which were finally handled by him, and for the prep- aration or revision of nearly all the technical descriptions printed in this volume. S. A. Forbes, Director of Laboratory Urbana, August 1, 1^08. THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS The Topography and Hydrography of Illinois* By Charles W. Rolfe, M. S. The State of Illinois may be described as a great plain sloping gently towards the south, the northernmost fifth of which is under- laid by rocks of Silurian age, while the surface rocks of the remaining four fifths are the limestones, sandstones, and shales of the sub- carboniferous and coal measures. The highest portion of this plain lies in the northern part of Jo Daviess and Stephenson counties, where the general surface has an elevation of something over 1 ,000 feet, and mounds rise more than 200 feet above this level. The highest point is Charles Mound, near the Wisconsin line, which is 1,257 feet above the sea. From this point the surface slopes rather rapidly to the east and south, declin- ing to an average altitude of about 800 feet in Lake county and of 700 feet in Whiteside county. South of Whiteside county the surface levels across the state from east to west are essentially the same wherever the line is drawn, but southward the surface slopes gradually until an average level of 400 feet is reached just north of the Ozark ridge. This ridge is an eastern extension of the Ozark Mountain range, whose highest peaks in Illinois are Williams Hill, in Pope county, which reaches an elevation of 1,046 feet, and Bald Knob, in Union county, 985 feet high. The average altitude of the ridge is from 750 to 800 feet. South of it the surface slopes rapidly to the low valley of the Cache River, the general altitude of which does not exceed 325 to 350 feet. The lowest point in the state. is at Cairo, where low water on the Ohio River is 268 . 58 feet above the sea. While the general surface of the state is unusually level, this does not mean that it presents no marked variations. Few of the 102 counties in the state have a difference of less than 150 feet between *The general system of the hydrography of the state is so largely a consequence of its surface geology that it can be clearly understood only by way of its geological antecedents and relations. For this reason Professor C. W. Rolfe. now and for many years head of the Department of Geology in the University of Illinois, was asked to prepare this chapter. With his discussion has been incorporated, with his approval, some additional matter relating especially to the waters themselves, compiled from field notes of the State Laboratory, and from more general sources. — S. A. Forbes. XVI FISHES OF ILLINOIS their highest and lowest points, while variations of 300 to 400 feet are often found. These differences, however, are not due to variations in the general level, but to the presence of deep pre- glacial valleys or of moraines, and often of both. For the present discussion the surface of the state may be divided as follows : 1. The northwestern unglaciated area. 2. The areas of the Iowan and the Illinoisan drift. 3. The area of the Wisconsin drift. 4. The unglaciated southern area. THE NORTHWESTERN UNGLACIATED AREA It is believed that at one time the entire northern fifth of the state was covered by rocks of the Trenton, Cincinnati, and Niagara formations, these following each other from below upward in the order named, and each covering the entire area. This portion of the state became dry land at the close of the Silurian and was not again submerged ; consequently, during the millions of years which elapsed between its emergence from the ocean and the advent of the first ice-sheet it was subjected to large erosion in spite of its low relief. At some time during this long period a low arch was raised across its northwestern corner, and here erosion became much more effective than on the less elevated parts. The streams of that time cut for themselves canons 250 to 300 feet deep, extending entirely through the Niagara and Cincinnati, but found their base level at or near the surface of the Trenton. An extensive peneplain was formed at this level, covering most of the area now included in the nine counties which lie farthest west. At various points over this peneplain, mostly in its northern and western parts, fragments of the denuded strata were left in the form of mounds which now rise above the general surface. Later the base Level was lowered and the rivers began again to deepen their chan- nels, and they have continued this process until now they flow in trenches cut in the rock often to a depth of 300 to 400 feet below the general level. With the mounds rising above the general surface and with the deep channels in which the rivers flow, the topography of the country is extremely broken for that of the Mississippi Valley. Much of the irregularity shown in Jo Daviess county, however, was produced during and since the glacial period, for the ice-shee1 which advanced on the state from the north was divided in southern Wisconsin ami left this part of our state un- i' iuched. THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XV11 THE AREAS OF IOWAN AND ILLINOISAN DRIFT Before describing these areas it is well to call attention to the fact that the preglacial drainage of the entire state seems to have been from northeast to southwest, and that while most of these early stream beds were completely filled by the drift from the ice-sheets, some of them were so large and deep that they were not entirely filled throughout their length, and now control the general direction of our larger streams. Probably, however, no one of them follows a preglacial channel throughout its entire length, and nearly all of the smaller streams flow in postglacial channels, the courses of which have been largely determined by moraines. Coming now to the areas mentioned in the last heading, it is believed that all of that part of the state which lies north of the Ozark ridge, with the exception of the extreme northwest corner, was covered by one or more of the earlier ice-sheets, and that, when these retreated, they left behind them a thick sheet of drift which filled the smaller channels completely, and some portions of the larger ones as well. Upon the general surface thus formed they also laid down ridges of drift which extended across the country, forming effective dams to the drainage. These dams, which are called moraines, varied in height from a few feet to a hundred or more, and from a few rods to one or several miles in width. They were generally concentric, and so lay nearly parallel to each other. AYhen they were far apart they inclosed large areas which had no outlets, and, filled by rains, formed extensive lakes; but when they were close together the intervening lakes were necessarily smaller and more numerous. The water supply of the time greatly exceeded evaporation, and so these basins were soon filled to the brim and overflowed at the lowest points of the moraines which surrounded them. These openings gradually deepened. Ulti- mately, by the lowering of their outlets, and also by filling with deposits, the lakes were converted into marshy plains or prairies. During the time in which the lakes were in existence nothing prevented the growth of vegetation on the confining moraines, and so these areas gradually came to be covered with belts of timber, between which were the lakes or marshes which afterward became prairies. As the lakes gradually became marshy, the water, flowing in >m one to the other through the concentric moraines, sought the lowest channels and formed continuous streams. Since certain of the pre- glacial channels were not completely filled with drift throughout reak away and the river fl< iws in an alluvial plain of good farming land. This plain is about 5 miles wide. Near the mouth of Rock River there are several small islands which divert the river into three channels. Two of these branches meet again near Milan, flowing into the Mississippi two and a half XXIV FISHES OF ILLINOIS miles distant, while the southern stream, known as Kickapoo slough, pursues a winding course southward and westward, opening into the Mississippi a few miles south of the mouth of Rock River. The upper Rock River is a clear, quiet-flowing stream with sandy bottom. Lower in its course the bed becomes more often rocky and the current quickens. Naturally, the water, unless roiled by freshets, keeps its bright, clear character until well down near the mouth. Its tributaries, however, at times pour in a flood of stained and muddy water, making the lower portion a turbid stream, while, of late, sewage and other contamination have done much to impair the original brilliancy of the water. Yet, as Illinois rivers go, it must even now be considered a clear stream, while the bold bluffs and out- cropping rocks along its banks make it one of the most picturesque rivers in the state. The principal branches of Rock River are Pecatonica, Kishwau- kee, and Green rivers. PECATONICA RIVER Pecatonica River rises in Iowa county, Wisconsin, in the driftless area, and flows south, entering Illinois in the northwest corner of Stephenson county. It then flows in a course a little south of west to Freeport, where it turns westward, entering Winnebago county near the center of its western boundary. Another turn is then made, to the north and east, the stream finally emptying into Rock River at Rockton. The Pecatonica is about 150 miles long, over half of this distance lying in Wisconsin. Its drainage basin covers 2,225 square miles. Its discharge in ordinary low water is about 940 cubic feet per second, and the average flow for the year is estimated to be over 2,300 cubic feet per second. Almost all of that portion of the basin lying in Wisconsin is included in the driftless area, the river entering the Illinoisan drift just above the Illinois state-line. It flows through this drift until, at a point 10 miles above its mouth, it inters the Iowan drift. For 10 or 15 miles above this point, how- ever, it follows closely the northern boundary of this drift. The country which the Petaconica drains is rolling, partly timber and partly prairie. The Indian name of the river (spelled Peeka-ton-oke on the old maps) is said by some authors to mean "muddy," and by others to mean "crooked." The river, especially in its lower portion, would fit either or both. The fall of the river averages only about half a foot per mile, and throughout its course it curves and winds about, not abruptly but in long undulating turns, through its rich alluvial THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXV bottoms, which in some places spread out to a width of 3 miles. Its earthen banks are low and rounded, and covered with heavy tim- ber. KISHWAl'KEE RIVER Kishwaukee River is formed by two branches which unite about 12 miles above its mouth. The northern branch rises in the Wis- consin moraine in central McHenry county, and the southern in the same moraine in southern DeKalb county. Each of these branches is about SO miles long, the whole system draining about 1,266 square miles. The lower part of the river lies in drift of the Iowan age, while the upper parts are in that of the Wisconsin age. The northern branch falls about 25 feet in the first 3 miles, and below this the descent averages two and a half to three feet per mile. The south- ern branch is a little swifter, with an average fall of about 4 feet per mile. The waters of this river are very clear compared with those of the Pecatonica. The banks of the river are not precipitous, al- though rising 40 to 50 feet high at some points. The entire river valley is low, undulating, semi-prairie country, more or less wooded. GREEN RIVER Green River and its basin are quite distinct in their character from the other tributaries of Rock River and their basins. The drainage basin of Green River covers about 1,131 square miles (10th Census) , all of which lies on a lake-plain of sand and gravel outwash from the Wisconsin glacier, the river following for most of its course the northern boundary line of the Wisconsin terminal moraine. The surface soil consists of peat, underlaid by sand and gravel. Through this the streams have found difficulty in making their way, unable to cut definite channels through it down to base level. The country consequently remains very imperfectly drained, and the waters gath- ering between the sand-hills have formed great peat marshes and bogs. Much is being done in late years, however, toward reclaiming these swamps by means of extensive tiling and ditching. The fol- lowing description represents the condition of this region before this work was so far advanced as it is at present. Green River is about 100 miles long, extending from eastern Lee county southwest across the corner of Bureau county and then west through Henry county to its northwest corner, there emptying into Rock River. Its headwaters are found in the elevated moraine forming the border of the Wisconsin drift in southeastern Lee county, and stand 950 to 1,000 feet above tide. The eastern stream XXVI FISHES OF ILLINOIS descends rapidly, 25 feet in a mile, to the sandy plain outside the moraine. There it soon enters the Inlet swamps lying about 775 feet above tide. These swamps are 10 miles long and 2 to 5 miles wide. Through them the stream has no definite channel but seems to be entirely lost. They are mostly covered with a dense prairie grass among whose roots a thin sheet of water is concealed in the wet seasons of the year. Towards the center the water is deeper and patches of cattails and rushes abound. From the western edge of this area, two to three miles southeast of Lee Center, the surplus waters of the swamps are gathered into a stream with a well-defined channel. This leads westward for 15 miles to another wet area, the Winnebago swamps, making a descent of about 3 feet per mile. These swamps are very similar to the Inlet swamps but much larger. Hills of sand rise in chains and clusters from the midst of them. These hills were originally heaped up by the winds from the sands of the old lake-bed. Some of them are 40-50 feet high and are covered with a scattering and stunted growth of trees. The inter- vening swamps are fringed with bands of thick-growing swamp grass on a miry, mucky soil. Within these are inner fringes of dense cane-like rushes and cattails growing so thick and tall that it is almost impossible to penetrate them. Then come stretches of clear water with hard sand bottoms. In the next 25 miles, to the crossing of the Bureau-Henry county line, the stream has a poorly defined channel, meandering about through a series of marshes among sand-hills but making a descent of 60 feet. In the remaining 35 to 40 miles to its mouth, the stream falls about 40 feet and main- tains a well-defined channel. In the lower 18 to 20 miles, below Geneseo, it has excavated a valley fully 20 feet in average depth and nearly half a mile in width. In this section of its course its uplands are far less sandy. Along the whole course of Green River, there are no bold bluffs except at Lee Center, where some low outcrops of Galena limestone are quarried. The Northwestern Area The waters of extreme northwestern Illinois differ sufficiently in condition and surroundings from those of the smaller tributaries of the Mississippi farther south to warrant their separate discussion in this report. The .surface drained by them is the southernmost part of a tract known to geologists as the Wisconsin driftless area, a region not covered by ice during the glacial period, and conse- quently wholly destitute of glacial drift. Because of its prolonged THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXV11 exposure to erosion its streams have reached the limit of their development, and run usually through deep valleys with rather a swift current, mostly unobstructed by rapids or falls. As a conse- quence of this perfect drainage and rapid flow, the surface waters quickly escape to the Mississippi ; but as the streams are fed to a 'considerable extent by springs flowing from the limestone rocks, they rarely are completely dry. There are no lakes, swamps, or other reservoirs for the sedimentation of the surface waters, and the streams are consequently easily roiled by storms, in the intervals of which, however, the water is comparatively clear. This driftless area of northwestern Illinois contains about 1,030 square miles, and includes all of Jo Daviess county, two thirds of Carroll county, and a part of Stephenson. The surface is rolling and somewhat broken, with a general elevation varying between 700 and 1,000 feet, but rising in mounds and flat-topped hills to the highest point in the state, an elevation known as Charles Mound, in Jo Daviess county, 1,257 feet above the level of the sea. The surface rock of this district is mainly Trenton limestone, with Cincinnati shales and Niagara limestone capping the higher hills. The principal streams of this region are Galena River to the north and Apple and Plum rivers farther south. Many additional smaller streams run down from the hills and bluffs to open directly into the Mississippi. GALENA RIVER Galena River, called Fever River on many maps, rises chiefly in La Fayette county, Wisconsin, which state contains also nearly half the 390 square miles of its drainage basin. It runs with a rather rapid course through the hilly country of western Jo Daviess county, often over a rocky bed, becoming comparatively broad and sluggish as it crosses the Mississippi bottoms west of the town of Galena to empty into the Mississippi River. APPLE RIVER Apple River rises in Lafayette county, Wisconsin, and flows southeast, then southwest and finally south, emptying into the Mississippi in northern Carroll county, Illinois. It has a length of about 45 miles and drains an area of possibly 250 square miles. It crosses the statedine at an elevation of about 950 feet, while its mouth has an altitude of only 588 feet. In Jo Daviess county, the upper channel of the river is narrow and the banks are steep and 150 to 200 feet high. In the lower part, the valley becomes broader XXV111 FISHES OF ILLINOIS and the banks recede until, in Carroll county, the river enters the broad bottom-lands of the Mississippi. Except for the headwaters of the eastern branch, the entire basin lies in the driftless area and therefore maintains its pre- glacial course. It has, however, received a marked accession of drainage because of the blocking of a preglacial tributary of the Pecatonica. This diversion occurs just below Melville, and for about 3 miles below this point the stream is in a gorge but little wider than its bed. The small preglacial Apple River is then entered. Outcrops of the Niagara formation occur frequently along the bluffs. PLUM RIVER Plum River rises in the northeast corner of Carroll county, and, following a westerly and southerly direction through many windings and abrupt turns, finally empties into the Mississippi in the center of the western boundary of Carroll county. It rises at an altitude of 900 feet but descends to 800 feet in the first 3 miles, to 700 feet in the next two and one half miles, and to 590 feet in the remaining 32 miles of its course. The banks are often ISO feet high, and in some places are very abrupt, while at other points a narrow valley of one eighth to one fourth of a mile intervenes. The Mississippi Bluff Drainage Under this head are included all of the small streams of western Illinois directly tributary to the Mississippi below those of the north- western area. Those here briefly described are Edwards River, Pope creek, Henderson River, Bear creek, Big creek, and Cahokia River. The character of a multitude of others may be sufficiently inferred from those of this list. The area drained by these western streams includes two strips of land bordering the Mississippi, one above and the other two below the Illinois basin. It consists of the eastern Mis- sissippi bottoms, varying in width from one to ten miles, and of high bluffs rising from 1 50 to 250 feet above the river, usually of loess, but occasionally with precipitous rock exposures. Many of the streams rise beyond this range of bluffs on the western prairies. EDWARDS RIVER Edwards River rises in southeastern Henry county, in two branches, and flows westward through this and .Mercer county. In the western pari of the latter i1 turns southward for a shorl distance before emptying into the Mississippi about one and one half miles THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXIX below New Boston. Below the junction of its two headwater streams the course of the river is remarkably straight and it has few tribu- taries. This is due to the fact that its basin lies in a narrow and shallow valley between two ridges having a general east-west direc- tion, and so the river drains only this narrow strip. Pope creek, which flows parallel with it on the south, lies in another such valley. Edwards River rises at an altitude of 800 feet, falls SO feet in its first one and one half miles, and another 50 feet in the next 18 miles. The mouth is about 520 feet above sea-level. The stream has a length of 60 miles. POPE CREEK Pope creek rises in northern Knox county and flows westward, emptying into the Mississippi almost opposite the mouth of Iowa River. It rises at an altitude of 750 feet, but its mouth lies at 520 feet. Its length is about 36 miles. The bluffs bordering the river are abrupt and often reach a height of 75 to 125 feet. HENDERSON RIVER Henderson River rises in the northwest corner of Knox county and flows westward and southward, emptying into the Mississippi at the center of the western border of Henderson county. It drains much of northern Henderson, northern Warren, and part of Knox county, and, although having a length of scarcely 50 miles, it fur- nishes drainage through its numerous branches for an area of fully 500 square miles. It rises at an elevation of 800 feet, and descends 100 feet in its first 10 miles, but below this the fall is gradual, the altitude at its mouth being 520 feet. BEAR CREEK Bear creek drains the southwestern part of Hancock county and the northern part of Adams — a possible area of 600 square miles. The main branch rises in southern Hancock county and flows south and west, emptying into the Mississippi opposite Canton, Mo. The source of this stream is at an elevation of 670 feet, while the mouth has an altitude of 460 feet. BIG CREEK Big creek drains a large part of Pike county and a little of north- ern Calhoun. It rises in northern Pike county ami flows soul he: ward toward the Illinois River, following a sag between two Illi- noisan drift ridges, and nearly reaching the Illinois opposite the vil- XXX FISHES OF ILLINOIS lage of Bedford. It then curves to the southwest, passes through a gap in the rocky ridge, which to the north and south constitutes the divide between the Mississippi and the Illinois, and enters the Missis- sippi opposite the town of Louisiana, Mo. The deflection to the west is due to the ridge of Illinoisan drift which follows the east border of the stream and prevents it from entering the Illinois valley. The river has a length of about 50 miles, rising at an altitude of 850 feet, but falling 100 feet in its first two miles, and below this averaging a fall of nearly 7 feet to the mile until it enters the Mississippi flats. The mouth is at an altitude of about 430 feet. CAHOKIA RIVER Cahokia River rises in southern Macoupin county and flows south and west, emptying into the Mississippi near East St. Louis. It is about 50 miles long, rising at an altitude of 640 feet, but falling 120 f< ( t in the first 6 miles. Below this it descends to 425 feet at Wanda, the point at which it crosses the Mississippi bluffs and enters the bot- tom-lands of that river. The mouth of the stream has an elevation of about 400 feet. The banks above Wanda are steep and abrupt, rising 100 feet or more on either side of the water. Illinois River System The Illinois and its branches drain an area of 29,013 square miles, distributed among three states. Of this area, 24,726 square miles are in Illinois, extending in a broad band, 250 miles long and averaging 100 miles in wi< 1th, i lirectly across the center of the state in anortheast- southwest direction. From the upper extremity of this band are two projections: one north into Wisconsin, covering 1,080 square miles in that state; the other east into Indiana, covering 3,207 square miles of its northern portion. This eastern projection forms the basin of the Kankakee River, while the northern one includes the basins of the Fox and Des Plaines rivers. It is the union of the drainage of these two projections which may be considered as the origin of the [llinois, this name being applied to the river from the point of junc- tion of the Kankakee and the Des Plaines in eastern Grundy couni v, Illinois. The Illinois flows westward for about 55 miles, turns rather abruptly southwest a little north of Hennepin and follows this direction until it empties into the Mississippi at the southern end of Calhoun county. The river may readily be divided into two parts: the upper Illinois, consisting of that portion of the river above the turn at 1 [ennepin : and the lower Illinois, below this point. THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXXI The lower part of the river occupies a preglacial valley, the south- ward continuation of the preglacial valley occupied by Rock River in southern Wisconsin and northern Illinois. The upper Illinois, however, flows through an interglacial and postglacial valley, the old "Chicago outlet." This outlet was the line of southwestward discharge from the basin of Lake Michigan across the low divides near Chicago and thence down the Des Plaines and Illinois to the Mississippi. It has a depth ranging from 20 to 70 feet, the excava- tion being almost entirely in beds of drift except for about 1 5 miles between Lemont and Joliet and 40 miles between Morris and Peru, where rock strata have been eroded. Throughout its entire length the bluffs are steep like river banks, and the deposits made by side streams on the edge of the valley are very meager — a feature which indicates that the stream had great volume, probably filling the channel from bluff to bluff, and a current sufficiently strong to carry nearly all of the detritus brought into it by the side streams. Since the Illinois is formed by the union of the Des Plaines and the Kankakee, it may be best to describe those streams first. DES PLAINES RIVER The Des Plaines drains a narrow intermorainic strip extending north and south a distance of 90 miles from Kenosha county, Wis- consin, to the head of the Illinois in eastern Grundy county, Illinois. The whole drainage basin covers an area of about 1,758 square miles, its greatest width being scarcely 25 miles. This region all lies within the Wisconsin drift, between two rather large moraines to the east and west of it, and containing many smaller moraines which have prevented the formation of good natural drainage-lines. The land is, consequently, very imperfectly drained, and contains numerous small lakes and marshes, although this condition has been much changed by extensive systems of tiling. A series of measurements by the U. S. Geological Survey gives for the average discharge 1,100 cubic feet per second. The water of the northern section is moder- ately clear, but becomes more turbid and polluted lower down. The bottom of the river and its tributaries is largely sand and gravel, with rock in its portions of swiftest descent. The Des Plaines has its source in an extended marshy valley in Kenosha county, Wisconsin. This valley is so nearlv level thai at times it is very difficult to tell which way the water flows. It stands 1 12 feet atiove Lake Michigan (Leverett) and drains northward into Root River as well as southward into the Des Plaines. The Des Plaines flows nearly parallel with the shore of Lake Michigan to a XXX11 FISHES OF ILLINOIS point about 10 miles southwest of Chicago. It then turns southwest for 40 miles, to its junction with the Kankakee. The course of the upper Des Plaines is governed by the moraines along the banks of Lake Michigan, following these more or less in their curves. At Summit it enters into the "Chicago outlet." At flood stages the upper Des Plaines still discharges into Lake Michigan through a por- tion of this old outlet which is known as "Mud Lake" and South Chicago River. Probably the entire discharge, until recent years, has been into the lake instead of down the "Chicago outlet," thus form- ing a system entirely distinct from the lower Des Plaines. In the upper portion of the river the fall averages only a little over 1 foot per mile, and its branches are almost all short and small on account of the moraines. The banks, especially on the west, are quite high, in some places reaching a height of 50 feet, but they are not abrupt. In the 40 miles from Summit to the mouth of the river, the valley averages about 1 mile in width and consists of a rather shallow trough cut out of limestone. This is covered with a thin bed of drift, and the banks of the river are consequently low. Just below Sum- mit there are 12 miles which are almost level, so that the land on each side of the river is poorly drained and swampy. Below this the river witl ens into Goose Lake, three and a half miles long and one third of a mile wide, through which it makes a descent of about 10 feet. The bed of the river narrows again, and just above Lockport it begins to descend very rapidly, dropping about 70 feet in 8 miles. Below this are two lakes, — one, known as Lake Joliet, 2£ miles below Joliet, and the other, Lake Dupage, near the mouth of the Dupage River, the two being three miles apart, and the river falling about 13 feet in the interval (Leverett). In the half mile from Lake Dupage to the junction of the Des Plaines with the Kankakee another descent of two and a half feet is made. The only true flood-plain bottoms lie within the seven miles between Lake Joliet and the head of the Illi- nois. These are within the range of backwater from the Kanka- kee, but are overflowed only in case of floods from that stream, having been built up to about the average high-water level. A canal. 100 miles long, called the Illinois and Michigan canal, starts from Lake Michigan at Chicago, and, cutting through the low sum- mit, inters the Des Plaines valley. It crosses the river at Joliet, and then follows along the right bank of this river and of the Illinois to Peru, where it enters the latter river. The principal branch of the! )es Plaines is the Dupage River .which rises in southern Lake count}-, and, flowing southward, empties into the Des Plaines only I miles a In i\ e its junction with the Kankakee. THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXX111 It is about 50 miles in length, and drains about 366 square miles of intermorainic country. It is a swiftly moving stream, the last 1 1 miles of its course having a fall of 80 feet. Its banks are generally low and rolling. KANKAKEE RIVER Kankakee River rises in a large marsh about three miles south- west of South Bend, St. Joseph county, Ind. It flows in a south- westerly direction to the southern boundary line of La Porte county, and then more westerly, crossing the Indiana-Illinois state-line in southern Lake county, Indiana. It then flows a little south of west to within a few miles of Kankakee, where it receives the Iroquois from the south. Thence it proceeds almost due northwest to near the northeast corner of Grundy county, where it unites with the Des Plaines to form the Illinois. The Kankakee is about 140 miles long; 85 miles lying in Indiana. Its drainage basin covers about 5,300 square miles, of which 3,200 square miles are in Indiana. This basin has its northern limits in the Valparaiso morainic system, and all of the important northern tribu- taries find their sources in the same system. Its southern limits, in the portion below the mouth of the Iroquois, are found in the Mar- seilles moraine. The Iroquois rises in a somewhat distinct area, draining basins south of the Iroquois and Marseilles moraines and passing through a gap in the latter moraine to enter the Kankakee. The eastern limits of the Kankakee basin are mainly in the Maxin- kuckee moraine of the Saginaw lobe. Probably the whole of the Kankakee basin was formerly an old lake, called now by geologists Lake Kankakee, and, at the same time that the old "Chicago outlet" was full, it may have been a line of discharge for the St. Joseph River, now a tributary to Lake Michi- gan, carrying also a large amount of glacial drainage from the Sagi- naw and Lake Michigan lobes. The basin of the Kankakee is generally level, but near the state- line, at Momence, occurs the first limestone outcrop in the bed of the river. This ledge or arch has so prevented the wearing down of the bed that a very large part of the drainage area in Indiana is one vast swamp. From its source to the statedine there is a direct dis- tance of only 75 miles, but within this distance the stream makes 2,000 bends and flows a total length of 240 miles. The difference in level between its source and the state-line is but 97 . 3 feet, shi >\v ing a fall of but 1 .3 feet to the mile. (Indiana Geological Survey.) The winding of the river reduces the fall to only 5 inches to the mile. (c) XXXIV FISHES OF ILLINOIS Above its junction with the Yellow River the amount of water is insufficient to form a well-defined channel. The water has an al- most imperceptible flow, and in many places wild rice, rushes, lily-pads, and aquatic grasses so choke the channel as to cause the flooding of the marshes during summer freshets. Below this point, however, there is quite a definite open channel, although the small tributaries are usually lost in the marsh before reaching the main stream. On the immediate border of the river there is a strip rang- ing in width from one fourth to One and one half miles which is heavily timbered. The only other timber is found on so-called islands whose surfaces rise 10 to 20 feet above the general level of the marsh. The open marsh is covered with a rank growth of wild grasses, bullrushes, sedges, reeds, wild rice, and other semiaquatic vegetation. Between the woodland bordering the river-bank and the marsh, as well as around the margin of most of the islands, there are dense thickets of elbow-brush, willows, etc. In 1882 there were almost 500,000 acres of marsh land within the valley of the Kankakee. It resembled an immense sponge, slowly absorbing the water during the wet season and as slowly giving it forth during the dry, so that the flow throughout the year was quite regular and uni- form in amount. At present, on account of the drainage of a large part of this marsh, the water flows off much sooner after it falls, and consequently the river is higher during the autumn and spring floods and lower at other seasons than formerly. In general the soil of the marsh is a dark, sandy loam, very rich in organic matter. It is very porous, but has the power to take up and retain large quan- tities of water. In the 14 miles below Momence, 111., to its junction with the Iro- quois, there is a descent of 25 feet. In the 33.5 miles from the mouth of the Iroquois to the head of the Illinois, the Kankakee falls 103 feet, or an average of 3 feet to the mile. There are rapids near Altorf atnl at Wilmington, where sudden descents of 20 feet are nude. In Indiana, as stated above, the bed of the river is com- posed mainly of sand and fine gravel, but at Momence it begins to (low over limestone, and from that point to its mouth it has a rock 1 >ni 1 1 iin, affording good foundations for dams for utilizing water- power and fasin lies within the Illinoisan drift area. With the exception of the headwater portion, above Carlinville, the main stream apparently has its course deter- mined by a preglacial line, there being a broad depression, deeply filled with drift, through which the creek takes its course. The trib- utary streams appear to be largely independent of preglacial lines. The basin is composed of gently rolling or nearly level prairies, which occupy the highlands between the streams and cover fully one third of the area, and by heavy belts of timber which skirt the streams. The soil is of a black, peaty character on the level prairies, becomes chocolate-brown on the more rolling surfaces, and degen- erates into a light ash-gray near the streams. The creek is about 80 miles long. Its fall is varied, some parts, as the lower 1 7 miles, having a fall of only one and one half feet to the mile, and other parts much more, as the four and one half miles just above this, the fall in this distance being 30 feet. Above this point the average fall is about 2 feet to the mile. The banks are high, in some places rising to 100 feet. In a few places the banks recede from the water's edge, leaving bottom-lands one half to one and one half miles in width. Kaskaskia River System The Kaskaskia River system drains a large part of southern Illi- nois, its drainage basin covering an area of 5,786 square miles. It is about 180 miles long, the narrow upper end reaching within 40 miles of the state of Indiana. The upper third of the basin lies in Wiscon- sin drift, and the other two thirds in the Illinoisan. The basin is composed of level or undulating country having black soil in the northern part and chocolate to light gray soil in the southern, under- Hi FISHES OF ILLINOIS laid by vellow to white clay. Heavy timber lands skirt the rivers, between which lie the prairies. In the southern parts great drift mounds, usually topped with timber, rise often from the midst of the prairies. KASKASKIA RIVER Kaskaskia River rises in Champaign county in the Champaign morainic system and flows southwest, emptying into the Mississippi in Randolph county, near Chester, at an altitude of 342 feet. Its descent is generally gradual, the most rapid section of its course being its passage through Moultrie county, where it makes a de- scent of 55 feet in about 18 miles, or 3 feet to the mile. In the head- water portion there is a fall of only 1 10 feet in the first 50 miles. In places there are pools several miles in length, the most conspicuous of these being in St. Clair county, where in a distance of 20 miles the fall is scarcely 10 feet. The upper 80 miles lies in the Wisconsin drift, the stream emerg- ing from the Shelbyville moraine near Shelbyville. In its headwater portion the channel of the stream is narrow and shallow to the inner border of the Shelbyville moraine. The banks are muddy as far as Sullivan, but sandy below this. The drainage of this section of the basin was originally very imperfect, and its undeveloped streams were often little more than series of swales and sloughs. Ditches and tile drains have greatly changed these conditions, however, and the run-off is now fairly prompt and complete. In crossing the moraine the Kaskaskia valley has an average depth of nearly 75 feet, and four miles northeast of Shelbyville the bluffs attain a height of 130 feet, although the channel is so narrow that it is not much more than a trench. The valley continues narrow for a few miles after entering the Illinoisan drift, but widens below the mouth of Robinson creek. This stream seems to follow the lower course of a drainage line (probably interglacial ), whose former headwater por- tion has heen concealed by the Shelbyville drift sheet. Its valley has a breadth of nearly half a mile, and the Kaskaskia retains this breadth below the mouth of the creek, increasing to three fourths of a mile in southern Shelby county. These bottoms are generally 14 to 16 feet above the ordinary stage of water, with sometimes a second bottom a few feet higher. During the wet seasons the river often covers the first bottom to a depth of several feet. The hills on each side of the river arc from 60 to 70 feet in height. On entering I tyette county, the river opens into a broad preglacial valley whose course farther north is buried under drift. The valley has a width of about 3 miles near Vandalia, but reaches a greater width farther THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS Jill south. It is so masked by drift that it presents the appearance of a broad shallow basin rather than a river valley. It continues nearly to the mouth of the river, where the width contracts abruptly to about a mile upon entering the subcarboniferous limestone which there borders the Mississippi Valley. The bottom-lands are subject to annual overflow, and are still covered with a heavy growth of timber. The stream is subject to great variations in volume as the com- pact clay subsoil promotes a rapid run-off and furnishes but little water in seasons of drought ; consequently, in summer and fall, the river dwindles to a very small size. At times it may be crossed dry- shod at Vandalia, where it is 60 to 70 feet wide. A rise of 20 feet in its lower course is not rare in flood time, and its flood -plain has been built nearly to that height above the stream-bed. The two principal tributaries of the Kaskaskia are from the west — Shoal creek and Silver creek. SHOAL CREEK Shoal creek drains an area of about 1,000 square miles, or one sixth of the entire basin of the Kaskaskia River (Leverett). This area includes most of Montgomery and Bond counties and western Clinton county. Shoal creek is made up of three branches known as West, Middle, and East Shoal creeks. West and Middle creeks unite to form the West fork, by the union of which with East creek, twenty miles below, the main stream is formed. From the rise of its branches to its mouth in the Kaskaskia this stream has a total length of 65 or 70 miles. The watershed has a distinct southward slope, the altitude at the headwaters being 700 to 750 feet, and at the mouth only 400 feet. The three branches have each formed a channel 50 to 75 feet or more in depth and nearly one fourth of a mile in average width in their passage through southern Montgomery county, and a similar depth is maintained as far down as the junction of the East and West forks near Greenville. Below this point the valley is more shallow, and the stream soon enters the Kaskaskia basin, where its bed is but little lower than the basin plain. East Shoal creek is bordered closely on the east throughout its entire length by a series of drift knolls and ridges (broken Illinoisan moraines). Shoal creek passes through a break in this system of ridges just below the junction of the East and West forks, beyond which its course is largely independent of drift ridges. Middle Shoal creek winds about among prominent drift knolls near Hills- liv FISHES OF ILLINOIS boro, and West Shoal creek is deflected eastward by a ridge of drift at its junction with Middle Shoal creek. The courses of these streams seem to be mainly independent of preglacial lines but largely determined by Illinoisan moraines. East Shoal creek touches the line of a deep preglacial valley near Greenville, but above that point it has opened a new course, in places trenching into the rock. Even the lower course seems to be largely independent of any preglacial line of drainage. SILVER CREEK Silver creek rises in the southeastern corner of Macoupin county, flowing almost due south through eastern Madison and St. Clair counties and emptying into the Kaskaskia opposite New Athens. It has a length of about 60 miles, draining an area of 500 square miles. The basin averages only about 10 miles in width. At its source the river has an altitude of about 650 feet. In its first 4 miles it falls 50 feet and in the next 16 miles a descent of 100 feet is made. In the lower part the fall is much less, being only 70 feet in the remaining 43 miles. In its southern half the watershed is diversified by drift ridges and knolls which rise in some cases to a height of 75 feet or more above the border districts. These for a few miles in southeastern Madison county constitute the east border of the watershed, but just south of the line of Madison and St. Clair counties the stream passes through the main belt of the ridges, and it has but few prom- inent ridges and knolls on its east below that point. At its mouth the stream has an elevation of only 370 feet, and the surrounding country, aside from the knolls, stands scarcely 400 feet above tide. Silver creek seems to be largely dependent in the direction of its course on glacial influences. It cuts into the rock at numerous points along its course, and its immediate bluffs stand at the general level of the bordering uplands. • Big Muddy River System Big Muddy River system drains an area of 2,3 74 square miles lying in an elliptical shape, with a major axis about 70 miles long running almost north and south, and a minor axis about 50 miles long. This drainage basin includes the greater part of Williamson, Franklin, Jefferson, Perry, and Jackson counties, the southeastern portion of Washington county, and the southern part of Marion county, which form the extreme southwestern part of the district covered by the Illinoisan drift sheet, lying in the low section just north of the Ozark ridge. The lower 20 miles of the river flows THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS lv through the Mississippi bottoms. With the exception of the ridge on the southern border, which stands 600 to 800 feet above tide, the basin has few points rising above 550 feet, the average level being 400 to 500 feet. The immediate borders of the main valley fall below 400 feet and the mouth of the stream at low water in the Mississippi is but 320 feet. The country is made up of gray prairies intersected by rivers whose bottom-lands are below the general level. These rivers are skirted by timber belts, so that a large por- tion of the basin is wooded. The bottom-lands also were formerly timbered, but parts have been cleared and put under cultivation. Over the greater portion of the area the drift is very thin, and rock divides separating the preglacial drainage areas are plainly discern- ible. The basin of the Big Muddy has been subject to long erosion, and consequently the soils are largely made of clays containing little humus and giving acid reactions. Big Muddy River has the characteristics of an old stream, in a land long exposed to erosion. It has cut its bed down to drainage level, and it runs its crooked course over a broad flood-plain. It rises in northern Jefferson county, and flows south and then west and south, emptying into the Mississippi about 5 miles below Grand Tower, Jackson county. It is about 127 miles long. Beaucoup creek en- ters from the north 25 to 30 miles from the mouth, and Little Muddy River enters from the same side about 10 miles farther up. These two streams together, drain about the same area as the main stream above the junction, and Beaucoup creek drains about one half more area than the Little Muddy. An eastern tributary, Crab Orchard creek, drains about 250 square miles of the district bordering the Ozark ridge. The river is very sluggish, and its volume is extremely variable. In the first eleven miles it makes a descent of about 100 feet, but below this the fall is not more than a foot to the mile. In times of spring flood its broad stream is overloaded with silt and its bottom a creeping mass, shifting its contour with every change in rate of flow ; and during the summer drouths it shrinks to little more than a chain of nearly stagnant pools. Throughout the greater portion of its course Big Muddy River occupies a preglacial line of drainage and meanders about in broad bottoms which have been filled with drift and alluvium to an ele- vation of from 500 to 600 feet or more above the rock bottom. Just below Murphysboro the valley becomes constricted to a width of about a mile in its passage through the elevated ridge which there borders the Mississippi. In its course through the lvi FISHES OF ILLINOIS Mississippi bottoms its eastern shore hugs the bluff, which rises 200 to 300 feet above the river. On its west are the low, flat flood- plains of the Mississippi. Above Murphysboro the banks are neither abrupt nor high, and they and the bed of the stream are chiefly clay. At Murphysboro, about 6 miles below the junction of Beaucoup creek, where the stream is about 160 feet wide, the water has some- times risen 30 feet, flooding the surrounding flats. Backwater from the Mississippi is felt at that point. The river is very properly named, as it carries great quantities of alluvium which the current is constantly shifting from one place to another. The Wabash System The Wabash basin, which covers the greater part of Indiana, in- cludes also about 8,600 square miles of eastern Illinois, drained by the Big Vermilion, the Embarras, and the Little Wabash rivers, and by several smaller streams in the southeastern part of the state. The greater part of its surface lies at an elevation varying between 300 and 700 feet, with the highlands around its headwaters and the region of the Shelby ville moraine rising approximately 100 feet higher. This moraine marks the southern limit of the Wisconsin glaciation, beyond which lies the lower Illinoisan. It divides the Wabash valley in Illinois into two distinctly different regions, the northern of which has the characteristics of a comparatively recent glaciation, and the southern those of a glaciated area long exposed to erosion. In the northern part the streams are few, and their branches are few and comparatively short. The uplands were poorly drained originally, and contained many marshes, sometimes very large, and many shallow lakes. The soil here is deep, black, rich in organic matter, slightly alkaline in reaction, porous, and rather coarsely granulated. In the southern section the soil has been washed and eroded for thousands of years, leaving it as an extremely fine-grained, slightly acid residue, from which most of the organic matter has disappeared. The streams of this long-exposed south- ern area have developed themselves freely in comparatively deep channels, through which their currents have a sluggish flow, and have lengthened their branches back to the uplands, which are thus effectually drained by natural processes. The large streams, especially in their lower courses, have formed extensive bottom- lands liable to overflow, and, owing to the thorough natural drainage of the country, the waters recede to a very low level during times of droughl THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS Ivil Hydrographic conditions in the Wisconsin glaciation have been greatly changed within comparatively recent years by large drainage operations, carried on at public expense under the operation of state law. Swamps, marshes, and lakes have virtually disappeared, and their places have been taken by rich and highly cultivated farms. Much less change has been made in the lower Wabash valley as a consequence of human occupancy, but the original rather genera] covering of both lowland and upland forest has been mainly re- moved, with the effect to expose the surface to more rapid erosion than heretofore, and to increase the extremes of flood and low water. WABASH RIVER Wabash River was given, by the earliest explorers, the name of Ouabouskigou, said to mean "white water" in one of the Indian tongues, and it bears this Indian name on the maps of both Joliet and Marquette. This was later contracted by the French to Oua- bache, the spelling of which has since been simply anglicized. The earlier explorers regarded the lower Ohio and the Wabash as form- ing one stream, to which they gave the latter name, while the upper Ohio bore either its present name or that of "la Belle Riviere." The Wabash forms, for 198 miles, the boundary between Indiana and Illinois, lying in this part of its course in a preglacial valley, the former bed of a very much larger stream. This valley, five or six miles across in its upper part, is filled with drift which buries the old stream bed to a depth of 60 or 70 feet, and is bounded by bluffs rising from 100 to 200 feet above the river. The Illinois section of the Wabash has a comparatively sluggish current, its fall being less than eight inches to the mile. Two, and in some places three, different levels are distinguish- able in the Wabash valley to-day. The bottom-lands of the river subject to overflow at ordinary high water are from twelve to fifteen feet above the stream, and at about the same height above these arc the second bottoms, covered with water only by exceptional floods; and in some places a terrace level may be traced half-way up the bordering bluff. The river flows for the most part along the western side of its valley, occasionally, indeed, quite close to the bluffs, leaving the bottoms largely on the Indiana side of the stream. The bed of the river is often rocky and the current locally swift, and rapids greatly interfered in early days with tin- use of the stream for transportation purposes. The waters of the Wabash are, like those of the Illinois and the Kaskaskia, commonly brown and opaque with lviii FISHES OF ILLINOIS suspended silt, never clearing even at the lowest stages; and the same is true of most of its tributary streams, especially those of the lower Illinoisan glaciation. VERMILION RIVER Vermilion River drains an area of about 1,500 square miles in Ford, Champaign, and Vermilion counties in Illinois, and a small section of Fountain and Warren counties in Indiana. It rises only a few miles from the source of a river of the same name which flows northwest into the Illinois, to distinguish it from which it is often called the Wabash-Vermilion or the Big Vermilion. Its course is generally south and east, and it empties into the Wabash 10 miles beyond the Indiana line. It has a length of about 81 miles, and a fall of 320 feet. Its source is in the midst of the Bloomington morainic system at an elevation of 800 feet. It flows thence south- ward between two ridges, known as the Roberts and Melvin ridges, and passes through the latter ridge, falling 70 feet in this distance of 17 -h miles. At this point it receives a tributary of about the same length from the west, which is known as the West branch of the Middle Fork. This branch also rises at an elevation of 800 feet and drains a sag or narrow plain between the Melvin ridge and the outer moraine of the Bloomington system. From this union the stream takes a southeastward course across the northeast corner of Cham- paign county and into Vermilion county as far as Potomac, where it turns abruptly southward and passes through the outer ridge of the Bloomington moraine. A few miles farther south it receives its larger western tributary, the Salt Fork, and the united stream then flows east for about 6 miles to Danville, takes again a southeast course, and follows this direction to its mouth. Salt Fork rises in western Champaign county at an altitude of 740 feet and flows south and then east for a distance of 50 miles. It drains a plain in eastern Champaign and western Vermilion counties, lying between the Bloomington and Champaign morainic systems. North Fork rises in northern Vermilion county at an elevation of 720 feet and flows southward for a distance of 37 miles, emptying into the Vermilion at Danville. It drains only a small area among the ridges of the Bloomington system. The entire drainage system of the Vermilion is independent of preglacial lines, the drift over this region being so deep as to cover completely the old rock divides. The river and its branches have narrow valleys, and in the1 upper courses the hanks are only from 10 THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS lix t < ) 5 0 feet high, and generally bordered by scattered patches of timber. In the lower parts the streams are skirted with strips of woodland from one to four miles in width, and the banks are steep and high. Bed-rock is not exposed in the upper portions, but at and below Danville the river has cut into the rock of the coal-measures to a considerable depth. Generally speaking, the headwaters of all these streams were originally prairie swales, lying in shallow valleys or in broad de- pressions of an otherwise plain surface. Here they were often choked with weeds in summer, and were very muddy in times of flood, but in their lower courses they often cut deeply into the drift, or even into the underlying rock, forming deep and narrow valleys, sometimes with decidedly gorge-like effect. In comparison with most Illinois streams, however, the waters of the Big Vermilion are in general fairly clear, and the bottoms relatively clean, forming a transition from the typical prairie streams to those characteristic of the adjacent Alleghany plateau. LITTLE VERMILION RIVER The Little Vermilion River rises in the southeastern corner of Champaign county and flows southeast, east, northeast, and south- west, a distance of about 60 miles, emptying into the Wabash River in Vermilion county, Indiana. Of this length 45 miles lie in Illi- nois. It drains a narrow strip covered by the Champaign till-sheet lying between two moraines, the northern of which completely separates the drainage basin of the Little Vermilion from that of the Vermilion proper. The river rises at an altitude of 710 feet, and falls 30 feet in its first 4 miles. In the next 9 miles a descent of only 10 feet is made, below which a fall of SO feet occurs in 4 miles. The descent then becomes more gradual and the stream crosses the state- line at an elevation of about 500 feet. In its upper part it is little more than a prairie drain, but it becomes of more importance farther down, where the banks are 75 to 100 feet high and lined with strips of timber 1 to 3 miles in width. EMBARRAS RIVER Embarras River drains an area of about 2,000 square miles in eastern Illinois. Its source is in the Champaign morainic system, immediately south of the city of Champaign. For about 20 miles it flows between the outer and the main ridges of the Champaign sys- tem, then cuts through the outer ridge in northern Douglas county. Thence it bears southeast, for about 10 miles, to a small till ridge lx FISHES OF ILLINOIS correlated with the Cerro Gordo moraine, crossing this in south- eastern Douglas county. Its course is then slightly west of south for 25 miles, at which point it leaves the Shelby ville or earliest Wis- consin sheet of drift, continuing southward 25 to 30 miles farther, to the neighborhood of Newton, where it changes to the southeast- ward and maintains this course to its mouth, a distance of 50 miles. The river rises at an altitude of 750 feet, while its mouth lies only 395 feet above tide, making a total descent of 355 feet, or an average descent of two and a third feet to the mile. In the last 53 miles, however, the fall is scarcely more than a foot to the mile. The upper part of the river, lying within the Wisconsin drift, drains only a narrow strip and has but few tributaries. This section of its basin is mostly prairie with woodlands skirting the larger streams, and the soil is a deep, black, and very fertile loam. Upon emerging from the Wisconsin drift, the river enters at once a much broader valley which appears to have been excavated prior to the Wisconsin stage of glaciation, for the valley gravels connected with the Shelby ville moraine head down the river bottom in a way to indicate the existence of this valley at the time of their deposition. The valley increases in width from one mile in Cumberland county to 2 miles in Jasper county, and 3 to 5 miles in Crawford and Law- rence counties. Below Newton its course is determined largely by a preglacial line of drainage, which possibly extends up the valley as far as the vicinity of Greenup, 18 miles above Newton. In this sec- tion of the basin strips of timber-land border the streams, and the bottoms are somewhat swampy and subject to overflow, but are gen- erally sufficiently dry to admit of some cultivation when cleared. In Lawrence county, between the Embarras and the Wabash rivers, there is an extensive marsh, known as Purgatory swamp, about 10 miles long and from 2 to 4 miles in width. The banks of the river arc 50 feel high in Cumberland and Jasper counties, but much lower near its mouth, although the uplands lie 50 to 100 feet above the watercourses. The interesl ing contrast between the upper and the lower courses of this stream, in respect to the number of its tributaries, the extent of its flood-plain, and the development of its drainage system gener- ally, is clearly traceable to differences in age between the two glacial anas through which it flows. ] l i l I.K WABASH RIVER Little Wabash River drains about 3,000 square miles in south- east crn Illinois. It lies in an oval basin, much broader in the middle THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS lxi than in its lower and upper parts. It extends, on the west, to the watershed of the Kaskaskia and on the east to the Embarras and Bonpas watersheds. The entire basin lies in the Illinoisan drift, and is made up of rolling prairies lying between the broad belts of wood- land which skirt the streams. The difference in level between the creek bottoms and the adjacent highlands does not usually exceed 50 to 75 or 100 feet. The river rises in southwestern Coles county, and flows south through Shelby and Effingham counties. In northern Clay county it turns southeast for about 50 miles, and then flows alternately southwest and southeast until it empties into the Wabash at the boundary line between Gallatin and White counties, eight miles, in a direct line, from the junction of the Wabash with the Ohio River. The length of the river is about 180 miles. Its source is in the Shel- byville moraine at an elevation of 740 feet, but it descends within 4 miles to 700 feet, to 650 feet in the next 2h miles, and to 600 feet 1 2 miles below. Another descent of 100 feet is made in the following 31 miles, while at a point 42 miles below this the 400 feet contour- line is crossed. The mouth of the stream, 104 miles distant, lies 323 feet above tide. Thus the total descent of the river is 317 feet, giv- ing an average fall of about 1 . 7 feet per mile. In the first 40 to 50 miles the main stream is largely independent of preglacial lines, and there is consequently little valley. The re- mainder of its course, however, is determined by a broad preglacial valley except for a short distance below Carmi, where it cuts across a projecting spur of hills leading in from the west. This valley, like others in this region, has been filled in its lower course with drift and alluvium to a level perhaps 100 feet above the rock bottom (Lev- eretf). It is from an eighth to a fourth of a mile wide in Effingham county, but below, reaches a width of one to three miles. At times the river is bordered locally by precipitous bluffs 40 to 50 or even 100 feet in height, while at other points there is a gradually sloping sur- face from the bottoms up to the level of the adjacent prairie. The river-bottoms are a rich, sandy loam, hut are valued little for agri- culture on account of the overflow to which they are subject during the annual spring freshets. They arc, however, valued for the heavy timber which covers them. The most important tributary of the Little Wabash is Skillet Fork which enters from the west near Carmi. The length of this stream is about 65 miles, not including the windings of its course, and it lias a watershed of nearly 1,000 square miles. It rises in northeast Marion countv and flows south and then southeast. Its lxii FISHES OF ILLINOIS source is at an elevation of 600 feet, but it has a fall of 100 feet in its first 6 miles and makes another descent of 50 feet in the next 12 miles. During the rest of its course it falls but 100 feet. In the upper, swifter section the precipitous bluffs rise to a height of 60 to 75 feet, and there is little valley; but in the lower part the stream occupies a preglacial valley similar to that occupied by the Little Wabash. Saline River System The Saline River system drains into the Ohio that portion of southeastern Illinois which lies immediately north of the Ozark ridge. Its basin covers an area of about 2,000 square miles, lying entirely within the limits of the Illinoisan drift. Part of the land is quite broken by hills and ledges which range in elevation from 10 to 80 feet above the high-water mark of the streams. A large part of the country, however, is level, and much of the land may be termed "wet," with here and there a not inconsiderable swamp or pond occu- pying, probably, old waterways. The basin is crossed by "Gold Hill," which extends through Gallatin and Hamilton counties in an east and west direction. This ridge, which attains a height of 343 feet above the high-water mark of the Ohio River, is crossed by the Saline River a few miles below Equality. The soil is light-colored clay loam, and a large part of it is still covered with thick timber. The river is formed in western Gallatin county by the union of North and South forks, the latter being joined by Middle Fork in the southeastern part of Saline county. From the point of its formation the main stream pursues its course along the base of the Ozark ridge in a southeasterly direction, emptying into the Ohio River in northeast Hardin county. The three forks of the river and their principal tributaries are, in the main, re-established along pre- glacial lines, and take meandering courses through broad valleys which have 1 ieen filled to an elevation of 50 to 100 feet or more above their rock bottoms. The main river is about 16 miles long, and in this distance it makes a descent of only about 35 feet. The banks of the river along its northern border are low, but on the south they rise abruptly and often to a height of 150 feet, especially in the upper half, where the river hugs more closely the base of the ridge. The South Fork is about 67 miles in length. In the first half mile, as it descends the ridge, it falls 50 feet, but the fall gradually diminishes to 50 feet in the last 24 miles. Its total descent is about 300 feet. The banks are rather high, especially along the south, where they rise 50 to 60 feet aUu\e I he water's edge. Middle Pork is onlv about 26 miles long, THE TOPOGRAPHY AXD HYDROGRAPHY OF ILLINOIS lxill with a fall of about 60 feet. North Fork in the first mile of its course has a fall of about 30 feet. In the remaining 35 miles a descent of about 60 feet is made. The banks of this stream are low and subject to frequent overflow. In southeastern Hamilton county the course of the North Fork is entirely lost for about 3 miles as it crosses a swamp. The course of the main stream is crooked and the current sluggish, with long stretches of quiet water where soft black ooze can accumulate year after year, and where a typically lacustrine vegetation can grow. Here Nuphar, Nymphcsa, Potamogeton, and the limnophilous species of filamentous algas abound. In dry weather the visible flow may almost cease in places, and in flood a full stream may fill the banks even to overflowing; but it is never quite a rushing muddy torrent, nor ever quite a dry creek with scattered pools floored with gravel or naked clay. Cache River Cache River drains the eastern part of Union county, the south- western half of Johnson county, the northern part of Massac county, and most of Pulaski and Alexander counties. The edges of this basin are not clearly defined, but it probably covers an area of about 600 square miles. It lies entirely in the driftless area which covers the southern point of Illinois, just south of the Ozark ridge. The basin is very largely made up of alluvial bottomdands which border all the streams, and which in southern Alexander county extend entirely across the state from the Cache River to the Mississippi. These bottomdands are generally flat, and are interspersed with cypress ponds and marshes, being mostly too wet for cultivation without a very thorough system of drainage. They are subject to annual inundations from the floods of the rivers, and are generally covered with timber, now being rapidly removed for lumber. The most elevated portions of these bottomdands, however, have a light, rich, sandy soil, very productive when cultivated. Farther from the streams, the surface of the country is roughly broken. The Ohio River may, at one time, have discharged wholly or in part through "Cache valley." which crosses southern Illinois a few miles north of its present course. Its point of connection with Cache valley is immediately north of Metropolis, where for a dis- tance of 4 to 5 miles a clay deposit has accumulated in the line of the i '1' I valley. The surface of this clay deposit stands only about 75 f< :i :1 above the present stream, and is much lower than the surface of the Tertiary deposits on either side. It is not known as vet. whether lxiv FISHES OF ILLINOIS the channel formerly constituted the sole line of discharge for the Ohio or not. Possibly the river divided its waters between the Cache and its present channel. The bluffs of the powerful stream which excavated the valley of the Ohio extend from the Mississippi half-way across Alexander county, and then turn northeast, leaving a bottom from 3 to 5 miles in width between them and the Cache. The headwaters of Cache River are in eastern Union county, the river winding first southeast, then south-southwest, south, and east, emptying finally into the Ohio River a few miles below Mound City. It traverses a distance of about 70 miles, beginning at an altitude of 500 feet. It falls 50 feet in a little over 2 miles, 100 feet in the next 15 miles, and only 70 feet in the remainder of its course. Near its head it has a definite channel, but just west of the Union-Johnson county line it enters its first cypress swamp. This, however, is very small, and the bottom-lands again become higher and drier, averaging about half a mile in width for the next nine miles. Then for a distance of about 3 miles there is scarcely any bottom-land, below which the river enters an extensive cypress swamp having a width of 5 miles in some places. A few miles above Collinsburg the bottom again becomes narrow and ledges of sandstone form the bed of the stream, which here is clear and swift. Below this point the water is nearly stagnant, brown in color, and full of drifted logs. The lowlands average about three fourths of a mile in width to near the mouth of Dutchman creek, where they spread out to almost two miles. At the Massac county line, Cache River enters the main swamp region which extends across Pulaski county, and below these swamps the river winds about through wide bottoms to its mouth. The backwater of the Ohio reaches up Cache River hardly as far as Ullin, and floods above this point are more immediately caused by the headwaters of the stream when their discharge is impelled by backwater. The country around the upper Cache is hilly and precipitous, and so in times of freshets it pours immense quantities of water into this lower flat, which then becomes a reser- voir. As the waters which the Cache carries come from rocks of subcarboniferous and cretaceous ages, they are somewhat different in mineral characteristics from any of the rivers heretofore de- scribed. Big Bay Creek ]'■]■■ Bay creek drains eastern Johnson and western Pope counties — an area very similar in character to that drained by the Cache. Tlie stream rises in northwestern Pope county, flows southwest into Johnson county, takes there a southeasterly direction, and empties THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS 1XV into the Ohio near Bay City. It has a length of about 40 miles, with an altitude of 750 feet at its source and of 300 feet at its mouth. In the upper 7 miles it falls 300 feet and the banks are steep and abrupt; but below, the river valley expands into a swampy region 3 to 4 miles in width. These swamps connect with those of the Cache River, and often the headwaters of the latter stream find their way to the Big Bay and down it to the Ohio. At other times, high water in the Ohio produces a flow through Big Bay, the swamps, and down the Cache. Much is now being done, through tiling and ditching, to separate completely the basins of the two streams and to make each course distinct. In the lower 8 miles of its course the banks again hug the river closely, and rise on either side to a height of 250 to 300 feet. The Lake Michigan Drainage In the northeastern part of the state there is a narrow belt of land from ten to twenty miles in width bordering Lake Michigan and sending its waters into that lake through many small, short streams, only two of which are of sufficient size to receive especial mention, namely, the Chicago and the Calumet rivers. Much of this area, including the present site of Chicago, was formerly part of a gnat glacial lake known to geologists as Lake Chicago, which existed at the same time as the "Chicago Outlet" (see page xxxi). It dis- charged its waters southward through this outlet instead of north- ward as at the present time. This tract of land now lies as a relatively level. plain, diversified with old lake-beaches and low glacial moraines. It is very poorly drained and is filled with swamps and lakes. The small short streams are mostly to be found in Lake county, where they drain a strip from two to four miles in width directly bordering the lake. They rise in the morainic ridge which here extends north and south along the shore at an altitude of about 700 ft., and from its crest they make very rapid and direct descents to the lake. Chicago River rises in northern Cook county and flows south and east for a distance of 26 miles, emptying into Lake Michigan about a mile and a half north of the Illinois Central station in Chicago. It rises in a swampy area at an elevation of 630ft. above tide and makes a descent of 20 ft. in the first two and a half miles of its course. I'm low this, however, it has almost no fall, the month of the stream lying at about 600 ft. above tide. Five miles from its source Chi- cago River is joined by the North Branch. This stream rises in (e) lXVl FISHES OF ILLINOIS Lake county in another swampy intermorainic area at an elevation of 660 ft., and in its length of 12 miles makes a descent of 50 ft. Although the upper courses of this stream and of the main river can not be definitely traced farther up-stream than mentioned above, they seem to drain indirectly a series of marshes lying be- tween moraines extending north and south within those directly bordering Lake Michigan and bounded on the west by the Des Plaines 'watershed. About one mile from its mouth Chicago River is joined by the South Branch. This river connects with the Des Plaines near Summit and, as stated in the description of the latter river, it has afforded a line of discharge for the upper Des Plaines from the time of the withdrawal of the lake down to historic times. The size and depth of its channel are such as to seem to demand the work of a stream as large as the Des Plaines. Even in quite recent years this river at high-water has been known to overflow into the South Chicago channel and thus to discharge some of its water into Lake Michigan. With the exception of a few miles at the head- waters of North Fork, the entire drainage system lies within the limits of old Lake Chicago. The southward course of. the stream outside of the lake bottom is occasioned by till ridges of the Lake Border morainic system, the one on the east preventing direct dis- charge into Lake Michigan. Within the limits of Lake Chicago the stream follows the slope of the old lake bottom. Calumet River has its headwaters in the Valparaiso morainic system south of Michigan City, Indiana. Its numerous tributaries also rise in this system, and they and the main stream, on descending from this ridge, flow in the lowland formerly covered by Lake Chi- cago. Here their courses are controlled to some extent by the lines of sand-dunes formed along the benches of the old lake, and, to a slight extent, by till ridges. The streams have almost no fall, and the section through which they flow is filled with swamps and lakes. The course of the river is meandering, and at times it is almost impossible to determine the direction of the flow of water, as in the swampy region near Blue Island. Lake Calumet, near Pullman, Illinois, is the largest of the many tributary lakes. The mouth of l he stream is at South Chicago, Illinois, at an altitude of 580 ft. GENERAL AND INTERIOR DISTRIBUTION lXYll On the General and Interior Distribution of Illinois Fishes The geography of Illinois is, in its most obvious features, so sim- ple and so monotonous that one naturally expects a similar sim- plicity and monotony in the geographic distribution of its plants and animals. The plan of its hydrography is as little complicated as the geography of its land areas. Surrounded on more than two thirds of its circumference by -three large rivers, the Mississippi, the Ohio, and the Wabash, with Lake Michigan covering a narrow strip at its northeast corner and draining a bordering region of scarcely greater area, its other waters flow southwestward into the Mississippi and southward into the Wabash and the Oh o, all mingling finally opposite its southernmost extremity for their journey to the Gulf. Its principal watersheds are inconspicuous ridges or slightly elevated plains, most of them originally more or less marshy, and the headwaters and tributaries of its various stream systems so approach and intermingle that in times of flood they formed an interlacing network, through which it would seem that a wandering fish might have found its way in almost any direction and to almost any place. Its climate varies considerably, of course, within the five and a half degrees of its length from north to south, but by insensible gradations, with no lines of abrupt transition anywhere to set definite boundaries to the range of its aquatic species. Its surface geology is more diversified than its topography, and its soils, although uniformly fertile throughout most of the state, dif- fer notably in their origin and physical constitution, some of these dif- ferences being such as to affect more or less the surface waters and, through them, to influence the conditions of aquatic life. The extreme northwestern and the extreme southern parts of the state are bare of drift, and their soil is derived immediately from the underlying rock ; but the surface of all the remainder of the state, excepting a small area above the mouth of the Illinois, hasbeen repeatedly worked over by ice in the course of the successive divisions of the glacial period. The oldest glaciated area, known as the lower Illinoisan glaciation, covers the greater part of southern Illinois and a narrow belt of the southeast part of the central section of the state. Next to this at the lxviii FISHES OF ILLINOIS northwest, and immediately east of the lower half of the Illinois River, is the middle Illinoisan; above this, in the west-central part of the state, between the Illinois River and the Rock, is the upper Illinoisan; and still farther north, in the Rock River basin, are the Iowan and Preiowan glaciations, reaching northward across the Wis- consin boundary. East of the last three mentioned, and north of the southern Illinois district, the Wisconsin glaciation, the most recent of the series, covers about a fourth of the state. It is to the peculiar features of the lower Illinoisan glaciation especially, that we shall presently be compelled to pay particular attention, because of their evident effect on the distribution of a considerable group of our fishes. The topographical relations of the state to the surrounding terri- tory are as simple and open as its own interior hydrography, and there is little to suggest the possibility of anything in the least pecul- iar in the general constitution or the relations of its fauna, or any- thing problematical or especially interesting in the details of the dis- tribution of its native fishes. We shall find reason to believe, how- ever, that this appearance is misleading, and that the subject, stud- ied in detail, contains matter of unusual interest, and presents prob- lems of considerable difficulty, a solution of which will lead us to some novel results. It is true, however, generally speaking, that the distribution of Illinois fishes reflects, in uniformity and relative monotony, the fea- tures of the topography of the state. A few species occurring in Lake Michigan and characteristic of the Great Lakes are, in fact , the only Illi- nois fishes which are definitely and permanently separated from their fellows in other Illinois waters by what may be called geographical conditions, and these conditions are not physical obstacles to their passage from Lake Michigan to the Illinois River. Excluding, for the moment, these fishes special to the Great Lakes, we find elsewhere in Illinois a general commingling and over- lapping of the fish population of the surrounding territory, the limits to whose range are climatic, local, and ecological, but topographic only in a secondary sense. THE GENERAL DISTRIBUTION Most of the 150 species of the native fishes of Illinois range far and wide in all directions beyond its narrow boundaries, thus illus- trating the breadth and the simplicity of our geographical affiliations with the surrounding territory; but a considerable number, on the GENERAL AND INTERIOR DISTRIBUTION lxix other hand, coming into Illinois from one direction, do not pass be- yond it in another, some part of the boundary of the general area of their distribution passing through our state. Several southern fishes go no farther north than Illinois; some northern fishes go no farther south ; some eastern species find here their western limit ; and a few western species range no farther east. The comparison of these geo- graphical groups whose areas overlap by their borders here in Illinois is a matter of special interest to the student of distribution, because it is in them that we find indicated the more remote affinities of our fish fauna, and from them, if anywhere, we may glean suggestions of its various origins. It will be convenient for a discussion of this subject to divide the general expanse over which Illinois fishes are distributed, into the following twelve districts: 1, the upper Mississippi Valley, including the Missouri and its tributaries; 2, the lower Mississippi Valley, in- cluding the Ohio and its tributaries ; 3 , the far North, extending north- ward from the headwaters of the Mississippi, east to the Lake Supe- rior drainage, and west to the Rocky Mountains; 4, the far North- west, separated from the preceding by the Rocky Mountains range ; 5, the Great Lake region ; 6, the district of Quebec and New England ; 7, the Hudson River district; 8, the north Atlantic drainage, from New England to the Chesapeake Bay; 9, the south Atlantic, from the Chesapeake Bay to Florida; 10, the peninsula of Florida; 11, the east Gulf district, bounded by the Mississippi drainage on the west; and 12, the west Gulf district, bounded by the Mississippi drainage on the east, and extending west and south to include the Rio Grande and its tributaries. The following table shows the recorded dis- tribution of our species over the territory so divided. fishes of illinois Table of the General Distribution of Illinois Fishes PQ a u o •a c - 3 R - ■d a! a u s c o T 3 K o c t 0 o a _;; n o 3 c 'S ID Ph -. --r : o 0 IS O ■a = Cfl CO w g CD & O d •a u a! to to CD n, a, CD -a c g O o 5 •o s IS "3 O W +-> ■/. o r: 0 t o 2; Li C3 Silvery lamprey (Ichthyomyzon) + + + + + + + + + + + + + + + + + + + + + + + + Paddle-fish (Polyodon) + + + + + + 4 + + + + + + + + + + + + + + + + + + + ' + + + Toothed herring (tergisus) + + + + + + + + + 1 + + + + + + Whitefish. + + + + + + + Eel 1 + + + f- + + + + + + + + + + + + Black-horse (Cy< leptus I Red -mi mi li buffali i (i r/1/ inella) + Mongrel buffalo [uriis) Small-mouth buffalo (bubalus) GENERAL AND INTERIOR DISTRIBUTION lxxi Table of the General Distribution of Illinois Fishes — continued O River carp (carpio) Blunt-nosed carp (difjormis) Lake carp (thompsoni) Quillback carp (velifer) Chub-sucker Striped sucker Common sucker (commersonii) Hogsucker (nigricans) White-nosed sucker (anisurum). . . Common red-horse (aurcolum) Short-headed red-horse (breviceps ) . Placopharynx duquesnei Harelipped sucker (Lagochila) Stone-roller (Campostoma) Red-bellied dace (Chrosomus) Silvery minnow (H . nuchalis) . . . . Hybognathus nubila Black-head minnow (/'. promelas) Blunt-nosed minnow (/'. notatus) , Horned dace (Semotilus) Opsopceodus emilice Golden shiner (Abramis) + + + + + + + + + + + + + + + + + + + + + + + -I- lxxii FISHES OF ILLINOIS Table of the General Distrib UTION OF llinois Fishes— -continued .S "(7) nj PQ a) M u o ■a c C w is •z. ■d c o a> .Q C : ■a 3 o '-£ a _2 < t o _3 3 o C/2 '- j a '2 « Oh id ■a ■c ■- 3 'J 0 o c a! vj o 6 a m w a> ft ft P in I C o ft. o Z Bullhead minnow {Cliola vigilax). . . . + + + + + + . + + + + + + ■f + + + + + + + + Straw-colored minnow (TV. blennius) . . + + + +■ + + + + + + + Spot-tailed minnow (N. hiidsonins) . . . + + + + + + + + + + + Common shiner {N . cornutus) + + + + + + + + + + + + + + + + + + f + + + + + Blackrin (N. umbratilis atripes) + + + + + + + + + Sucker-mouthed minnow {Pht naco + + + + + I Long-nosed dace ( R. < atarcu tee) + + ! 1 + + GENERAL AND INTERIOR DISTRIBUTION lx: Table of the General Distribution of Illinois Fishes — continued g PQ M •J +-> U 0 a B 2 B o T 3 K b t o V. o +3 fi < +j 3 O '/. ,5 "3 g 8 -r ■c : 3 O W 0 O ■d B ts t/i 3 a o w ■a n W a C _^ — i o 55 o CO 3 w C 'c a; PL — •c _o 0 a! W 0 O •d c C8 w w a) o d X) H s Ih o a P, - 01 O — c - a a ■J > 2 C 0 w •a 3 a +-> < z V. 3 O CO - 3 W 3 'c — - -r 'C _o E 3 w a! W 0 '£ o C vi t-. & o 6 5 2 p. ft p — a a u O o 2 — C3 3 5 CD U O Ft, J3 t 0 u a! + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Bluee;ill (pallidas) + + + + + + + + + + + + + + + + + + + + + + + + + + 1- + + + + + + + + + + + Sauger (5. canadense griseum) + + + + + + + + + + + + + + + + + + + + + + Black-sided darter (//. aspro) + + + + + + + + + + + + Green-sided darter (blennioides) 1 + + 1 + + + + 1XXV1 FISHES OF ILLINOIS Table of the General Distribution of Illinois Fishes — concluded V •d — B B ni at 15 d o w o S o .5 s TJ •a X PQ y. u o 4-» a a •0 S3 V — > u c B CO ca cS '- C < < 3 S § 3 u o J3 t, o +-> 0J 3 .S jC ■a 2 X u 3 : 3 t-l o is o a (A of o a X X W Ph w i-l h-> Hi fn + + + + + + + + + + Blue-breasted darter (E. camurum) . . . + + + + + + + + + + Rainbow darter (E. cceritlenm) + + + + + + + + Fan-tailed darter (E. flabcllare) + + + + + + + + + + + + + + 4- + + + White bass (Roccus chrysops) + + + + + + + + + + + + + + + + + + + + + + Uranidca kumlienii Burbot {Lota) + + + + + + 108 53 1" in 15 23 56 134 131 17 1 37 GENERAL AND INTERIOR DISTRIBUTION lxxvii Arranged according to the number of Illinois species in each, these districts succeed each other in the following order. Districts No. of species Per cent, of all Illinois species Lower Mississippi and Ohio valleys . . . Upper Mississippi and Missouri valleys The Great Lake basin The east Gulf district Quebec and New England The west Gulf and Rio Grande district The south Atlantic district The north Atlantic district The far North The Florida peninsula The Hudson drainage The far Northwest 134 131 108 56 53 47 45 40 37 23 19 4 SQ 87 72 37 36 31 30 27 25 15 13 3 Next to the two Mississippi Valley districts and the Great Lake basin, which average 124 Illinois species, our fishes are most largely represented in the east Gulf and the Quebec and New England dis- tricts, averaging 54 Illinois species — the first closely related to the lower Mississippi, and the second a continuation eastward of the Great Lake basin. Then follow the north and south Atlantic and the west Gulf districts, with an average of 43 species; the far North, the Florida peninsula, and the Hudson River districts, with 37 to 19 species; and, finally, the far Northwest, with but 4 Illinois species. The northern and the southern affiliations of the assemblage of fishes represented in our Illinois collections may be contrasted by comparing the list of Illinois species occurring in either or both of the more northerly divisions — that is, the far North and the Quebec and New England districts — on the one hand, with a list of those found in either or all of the three most southerly districts — that is, the Florida peninsula, the east Gulf, and the west Gulf and Rio Grande — on the other hand. In this northern list of Illinois fishes there are 64 species, and in the southern list there are 77 ; but 25 of these species are more or less common to both north and south, leaving 39 Illinois fishes distinctively northern in their distribution and 52 distinctively southern. Northern and southern species thus mingle in our territory in unequal proportions, the southern element largely preponderating. If we look to the further distribution of the northern and south- ern elements of our fish population, distinguishing northeastern from lxxviii FISHES OF ILLINOIS northwestern species, and southeastern from southwestern, we find that the southeastern species largely outnumber the southwestern in Illinois, and that the northeastern outnumber the northwestern. Thus there are 47 species of the west Gulf and Rio Grande region in this state, and 58 species of the east Gulf and Florida districts. Further, there are more species known as common to Illinois and the far northeast than there are to Illinois and the southwestern dis- trict of the west Gulf and the Rio Grande. Notwithstanding the much greater distance from us of the Quebec and New England district, there are 53 of the fishes of that region known in Illinois to 47 of those of the west Gulf district. The northeastern fishes have, however, been much more carefully collected than the southwest- ern, and an equal knowledge of both districts might change these relative numbers. THE INTERIOR DISTRIBUTION The interior distribution of the fishes of the state may best be ex- hibited by treating each considerable stream-system as a unit, and comparing the fishes of each such system with all the others. The state may be conveniently divided into ten such hydrographic districts, as follows: 1. The Galena district, including the streams of the northwest- ern unglaciated area, most of which empty into the Mississippi through Galena, Apple, and Plum rivers. 2. The Rock River dis- trict, extending southward and westward from the northern bound- ary of the state to the Mississippi at the mouth of the Rock. 3 . The Illinois district, including the entire drainage of the Illinois River. 4. The Michigan district, a narrow strip along the borders of Lake Michigan — the Lake Michigan drainage — most of which centers in the Chicago and the Calumet rivers. 5. The Mississippi River, and an irregular strip adjacent not included in any of the more definite river systems and mainly drained by small streams of the bluffs and neighboring highlands. This district is divided by the lower end of the Illinois basin. 6. The Kaskaskia basin. 7. The Illinois drainage of the Wabash, including that stream itself so far as it helps to form the boundary line between Illinois and Indiana. 8. The basin of the Big Muddy River, in the southwestern part of the slate. 9. The Saline River basin, in the southeastern part of the state. 10. The Cairo district, the driftless area of extreme southern Illi- nois, drained by the Cache River and smaller tributaries of the Ohio. The Ohio itself is included in this last district. GENERAL AND INTERIOR DISTRIBUTION lxxix The following list and table gives the details of the distribution of the species in a way to show the number of collections of each species made by us from each district. A cross opposite a species name indi- cates that the species occurs in the basin mentioned at the head of the column, but that it is not represented by preserved collections affording numerical data. Interior Distribution op Illinois Fishes by Rtver Systems Species and Number of Collections of each Districts Number of species . Collections made. Silvery lamprey Brook lamprey Paddle-fish Lake sturgeon Shovel-nosed sturgeon. White sturgeon Long-nosed gar Short-nosed gar Alligator-gar Dogfish Mooneye Toothed herring Gizzard-shad 44 13 « 92 73 Si 1 28 1115 12 57 07 20 5 7 20 52 + 27 1 8 89 1 + 1 . . . + + + 4 10 4 + 3 + + 1 69 41 + 95 103 + 42 10 55 u 101 Sections 120 12.-! 95 2691083 3 o ■/. 119 192 + + + + + 0 + + + + + + + lxxx FISHES OF ILLINOIS Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — continued Districts Sections V > 5 P C 'S, p. ^2 •d — a! C u - O s M o o Pi "3 t— ( u 'Js o 'tfj OS m rt rt 3 bo 5 D 0 rt 8 3 u X. o 2 a o 3 O C/2 ? 1 i 2 + 4- + + Whitefish. + + + + 0 0 0 Lake herring 0 + + 1 + + 0 + + 0 + + + + 0 Eel + i 28 17 + 2 9 1 + + + Black-horse + 1 1 1 2 l 4- Mongrel buffalo + 1 1 1 46 1 1 1 9 ? 1 2 + + + + + + + 4- 1 + Blunt-nosed car]) 1 6 54 S 15 21 3 3 + + + 10 39 1 1 + + + + 0 Quillback carp 1 1Q 1 8 1 + + ( liub-sucker 4 1 14 48 13 69 1 2 21 n 47 16 26 6 1 7 1 3 10 3 9 + + + + + + + Striped sucker 1 1 + Common sucker 9 5 + Long-nosed sucker. . . . + + 0 0 Hogsucker 1 1 1 61 1 9 97 1 + 4- + White a ised sucker 2 2 13 14 90 + 1 5 + + + + + < i immi mi red hi irse 10 25 1 2 4- Sin irt -headed red hi in e 4 39 1 < ? + + + 4- GENERAL AND INTERIOR DISTRIBUTION I XXXI Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — continued Placopharynx duquesnei Harelipped sucker Stone-roller Red -bellied dace Silvery minnow Hybognathus r.ubila Black-head minnow. . . . Blunt-nosed minnow Horned dace Opsopaeodus emilice Golden shiner Districts 1 20 4 6 3 8 3i 9 3 18 1 i 14 Bullhead minnow. . . . Notropis anogenu-. . . Notropis cayuga N. heterodon Straw-colored minnow Notropis phenacobius. . N gilberii N. illccebrosus Spot-tailed minnow....!. I Redfin. 1 X 99 13 86 67 162 72 49 183 110 2 29 81 108 2 IS 2 133 142 m M V 3 M o o Pi 0) > w 'o u - c _ 5 C3 cS a! A! w « m § s? S u t-i W s 0 u '3 o O ■z, 1 a CJ a 3 O 3 1 34 19 116 105 l 8 99 71 22 2 3 1 6 12 + + + + + Common shiner 11 14 + 1 + n 0 1 S 21 1 in S ? 5 4- + + 3 ? s 4 82 8 6 8 4 19 4 6 11 + + + + + Notropis ritbrifrons Blackfin 0 2 9 67 4 7S 3 25 25 17 56 58 36 5 11 19 + 8 + + + + + + 4- Sucker-mouthed minnow 2 15 13 1 4 + Long-nosed dace 1 0 n + Black-nosed-dace 1 7 4 1 1 + 4- 0 + 4- Spotted shiner 0 n 3 1 1 + + 4- Silver chub 2 7 90 10 10 37 5 16 4 2 4 4 1 3 2 1 0 + + 0 o (1 + + + 0 + + + Storer's chub 1 12 7 8 4- River chub 1 + Flat-headed chub 4- 1 + 1 + 4- h talurus anguilla + 1 hannel-cal 17 10 - + 7 17 •M .' 1 2 + + + 0 + Great Lake cattish 0 general and interior distribution i Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — continued Dist ricts Sections u3 O +^ C ■o - c ^J en u > Q ol >. X! Q C 3 O > s M o o Di '3 c e M IS o .2* w '5, w a! w a! w J3 a! a! -T ■d 3 s m en Q o u '5 o o +-> c O +J 3 o w 3 S2 42 144 10 l IS IS 3 4 6 4 10 + + + + + + + i 19 + Black bullhead l 11 35 4 6 + + 2 3 3 ? 22 32 1 3? 2 1 1 1 1 1 14 2 2 ?1 + + + + + + + + 4- 0 S 8 + 5 1 1 18 61 1 2 2 + 0 + 0 + + + + + + + + Slender stonecat 1 2 1 6 9 + 1 1 1 26 4 19 1 7 5 1 6 + 8 5 i i 1 4 + + Pike 2 17 + i 1 1 + + + n 0 0 Menona top-minnow. . . . 1 1 7 + + + 0 1 7^ 1 8 5 + + + ( c immon top-minnow . . . 1 6 66 i. 23 58 8 17 27 + + + 1 1 4 1 9 Q 0 + + Ckologaster papilliferus h 0 0 + 1 2 1 + + 0 0 o Nine-spined sticklebai 1. Trout-perch o 14 1 + + 0 lxxxiv FISHES OF ILLINOIS Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — continued Districts Sections a> a> O +* C •d •c u u > a) u Q 3 >* Q i> Pi C ft T ■7-1 UJ 01 a H Q 5 M --> o Pi "o oj s? o (A a! [A OJ OS ,0 3 s? S V M o u '3 o 1 c o 0 V. Brook silverside 1 6 80 54 2 2 l 0 21 11 + + + + + Pirate-perch 7 11 0 + 5 1 0 o + 9 0 110 7 1 1 6 14 3 1 6 + + + 8 1 in 3 1 5 8 13 T 1 + + + l 35 83 158 3 1 1 10 57 1 1 6 7 2 6 12 8 2 11 15 0 + + + + 0 + + + + + 4 3 20 1 1 3 3 16 2 5 33 + + 2 + Lepomis ischyrus 0 /,. symmetricus 9 3 4 o 1 + L. euryorus 1 0 + 0 24 37 1 1 27 2 57 + + + + + Long-eared sunfish 3 7 8 16 + Orange-spotted sunfish 5 112 22 15 23 2 3 3 + + + Bluegill ? 7 170 1 6 3 18 1 1 6 + + + Eupomotis heros 5 1 0 0 + Pumpkinseed 4 82 4 2 1 1 + + + Small-mouthed black ir, 6Q 5 ? 8 1 3 + + + Large-mouthed black 7 135 4 13 8 33 ? 4 12 + + + GENERAL AND INTERIOR DISTRIBUTION lxxxv Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — continued '- +J > tfi o n > g cti s in C ^i O o C nl 0 rZj o Pi H-t Pike-perch Sauger Yellow perch Log-perch Hadropterus evermanni. . . II. phoxocephalus Black-sided darter 2 Hadropterus ouackitcB. II. evides II. si ieriA s 'aster shumardi . Green-sided darter. . . . 1 Districts Sections a £ i + 4 12 IS Ji ihnny darter Boleosoma camurum i rystallaria asprella . Sand darter Banded darter Blue-breasted darter Etheostoma ioww . . . . its 4 Rainbow darter 2 9 20 1 13 75 35 3 58 70 1 14 + 100 45 7 ?1 6 1 1 1 1 19 39 6 42 1 m 11 10 3 O tn lxxxvi FISHES OF ILLINOIS Interior Distribution of Illinois Fishes by River Systems Species and Number of Collections of each — concluded Districts Sections en u 9) CU hn rt O +j C ■o m c +j +-> w S c O 0) > 2 u o > <2 'S D c to o § '5- 'tn w i a! 12 m tn a! en a! s s to s rt-nosed gar ■ ipsopceodus emilicB ( 'hub-sucker Small-mouth buffalo Boleosoma catnurum Common bullhead Quillback carp Rainbow darter Short-headed red -horse. . Long-eared sunfish White bass Rock bass Log-perch Stonecat Notropis cayuga Red-mouth buffalo I >ogfish • I i p miis miniatus Mud cat Notropis jejunus . . Banded dai ter Long-nosed gar Pike-perch Mud minni m Mi mgrel I >uffali i Collections 54 54 53 52 ¥) IS \t 45 42 39 30 39 37 36 35 .5 5 32 29 28 27 24 22 21 21 20 2(1 18 17 Species Pike Notropis gilbert! White-nosed sucker. . Trout-perch Cottogaster shwmardi. . Striped sucker Red-bellied dace Sauger Boleichthys fusiform is . Silvery lamprey Menona top-minnow . . Fan-tailed darter. . . . River carp Least darter Lake carp Paddle-fish Toothed herring Notropis rubrifrons . . . Storer's chub Sand darter Blue-breasted darter Freckled stonecal .... Miller's thumb Black nosed dace I- in ymba buci ata Skipjack S] ii it ted shiner / epomis isi h v us Collections 17 15 14 14 14 13 13 13 13 12 11 11 11 10 10 8 S 8 7 7 6 5 5 1 I 3 3 3 GENERAL AND INTERIOR DISTRIBUTION Ixxxix Species of the Illinois Basin, and Number of Collections containing each — concluded Species Collections Species Collections Hadropterus evermanni. . . . 3 Brindled stonecat Burbot 3 2 Slender stonecat Brook stickleback Xotropis phenacobius 2 2 Lepomis symmctricus Lepomis euryorus 2 Hadropterus scicrus N. illecebrosus 2 + Viviparous top-minnow. . Shovel-nosed sturgeon .... + + Black-horse Eel + Placopharynx duquesnei. . , Ictalitrns anguilla + Notropis pilsbryi . . + Hybopsis kyostomus , Green-sided darter + 1 Of the twenty-three Illinois species which have not been taken by us in the Illinois River or its tributaries, two are distinctively western fishes, and occur but rarely anywhere within our limits; nine are southern species, few of which have been found as far north as the mouth of the Illinois, and one other is only southern in this state; two are northern species which barely reach our borders ; five are typ- ical fishes of the Great Lakes; one has been found by us only in the main Mississippi and the Ohio ; one is a subterranean fish of strictly local occurrence; and the two remaining species are very rare in this state. Further particulars as to the species of these various geograph- ical groups are given in the following classified list. Illinois Species not found in the Illinois Basin western (2): // ybognathus nubila Flat -headed i bul i northern (2): Long-nosed sucker Nine spined s1 ii 1- leback xc FISHES OF ILLINOIS SOUTHERN (10) : Harelipped sucker Pigmy sunnsh Round sunnsh Eupomotis hcros Hadropterus ouachitcc H. evides Crystallaria asprella Etheostoma obeyense E. squamiceps Brindled stonecat GREAT LAKES (5) : Whitefish Lake herring Lake trout Coitus ricei Uranidca kumlienii MAIN MISSISSIPPI (1) : White sturgeon SUBTERRANEAN (1): Chologaster papilliferus RARE IN ILLINOIS (2): Brook lamprey Long-nosed dace As the Illinois basin contains 128 of the 150 species taken by us in the state, it is evident that the other and smaller basins must differ from this negatively rather than positively. Being not only much smaller, but also much less complex than the Illinois district, and offering less variety of situations for fishes as homes and places of resort, they may lack many species which find a fit environment somewhere in the Illinois or its dependent waters, but can contain relatively few not found there as well. Regarded from this standpoint, the Michigan district is farthest removed from the Illinois ichthyologically, and of its fifty-seven spe- cies nine (16 per cent.) are wanting in the Illinois basin. The Cairo district differs much less, eight of its one hundred and one fishes being without representation in our collections from the Illinois sys- tem. Next follows the Wabash basin in Illinois, with ninety-five species and a difference from the Illinois basin of 6 . 1 per cent. ; the Galena district, with forty-four species and a difference of 4.6 per cent. ; the Saline district, with fifty-five species, and a difference of 3 .8 per cent. ; and the Mississippi and its marginal area, with ninety- seven species, 3 . 2 per cent, of which are wanting to the Illinois streams and lakes. The Kaskaskia and the Big Muddy, on the other hand, which arc scarcely more than extensions of the Illinois district downward to the southern end of the state, contain virtually no fishes i mi in the main district, the Kaskaskia but one out of sixty -nine (1 .4 per cent.), and the Big Muddy none out of forty-two species. The Rock River district differs from the Illinois by only three species out of ninety two (3 .2 jut cent.). These data arc presented more com- pactly in the tal ile fi illi wing. GENERAL AND INTERIOR DISTRIBUTION X Differences between the Smaller Districts and the Illinois Basin Districts Species in dis- Species not found in Illi- trict nois basin 12S 57 9 101 8 95 6 44 2 55 2 97 3 92 3 69 1 42 0 Ratios of differ- ence Illinois Michigan. . . Cairo Wabash Galena Saline Mississippi. Rock River Kaskaskia. , Big Muddy. .16 .08 .061 .046 .038 .032 .032 .014 .000 Five species were found in the Illinois system and not in any other — three of them minnows of the genus Notropis (anogenus, phenacobius, and pilsbryi), one of them a sunfish (Lepomis euryorus), and one of them a darter (Hadropterus evermanni) . All of these spe- cies have been very rare in our collections, occurring only from one to three times each, and it was probable that they would be found, if at all, where the largest number of collections was made. The Galena district is distinguished from the Illinois basin espe- cially by the presence of a minnow and a darter (Hybognathus nubila and Crystidlaria asprella), the latter southern in its main range, and the former western, not occurring, indeed, farther east than western Illinois. These two fishes appear in the Rock River basin also, to- gether wit h another distinctively western darter (Hadropterus evides) . In the Michigan district, besides the five lake fishes already referred to — the whitefish, the lake herring, the lake trout, and two cottoids or miller's thumbs, Cottus ricei and Uranidea kumlienii — are the brook lamprey, the long-nosed sucker, the Great Lake catfish, and one of the sticklebacks (Pygosteus pungitius). All but the lamprey (which is rare in Illinois) arc northern species no1 taken by us in the Illinois valley. The Mississippi distrid is distinguished from the XC11 FISHES OF ILLINOIS Illinois by the presence of the rare white sturgeon (Parascaphirhyn- chus albus) , hitherto taken only in the Mississippi itself, and by a southern darter and a western minnow already referred to. In the Kaskaskia district we find another southern darter (Etheostoma squam- iceps). The six fishes of the Wabash district not found in the Illinois or its tributaries, are all southern species. The Big Muddy list con- tains no species not found in the Illinois basin ; and the Saline River district contains two southern darters {Etheostoma squamiceps and E. obeyensc). And, finally, among the eight species by which the Cairo district differs from the Illinois are three southern and two western species, a cave-fish, and two species of general distribution but rare in Illinois (Lampetra wilderi and Rhinichthys cataract®). Thus, of the twenty-three Illinois fishes not found by us in the waters of the Illinois basin, eight are distinctively southern, six are purely northern, if we include in this number the Great Lake fishes, four are western, one is an extremely local cave-fish, and four are so rare in Illinois that their appearance in any waters is a matter of unusual chance. The limitation upon the range of these imperfectly distributed species is thus climatic and general, and not geographic or local. This state lies on the extreme borders of their proper terri- tory, and they are not found more commonly in our waters because climatic and other general conditions most favorable to their main- tenance, here reach the vanishing point. Lists of Species distinguishing different Districts from the Illinois Basin galena district (2): kaskaskia river district (i): Hybognathus nubila (Western) Etheostoma squamiceps (Southern) Crystallaria asprella (Southern) WABASH DISTRICT (6): rock river district (3): Harelipped sucker (rare; Southern) Hybognathus nubila ( Western ) Pigmy sunfish (Southern) Hadropterus evides (Western) Eupomotis heros (Southern) Crystallaria asprella (Southern) Hadropterus ouachitce (Southern) Crystallaria asprella (Southern) Michigan district (9): Etheostoma squamicep s (Southern) Brook lamprey (rare) . Long-nosed sucker (Northern) saline river district (2): Whitefish (Great Lakes) Etheostoma obeyense (Southern) Lake herring (Great Lakes) E. squamiceps (Southern) Lake troul (('.real Lake i Great Lake catfish (Northern) Cairo district (8) Nine-spined sti< I lebai 1. (Northern) Brook lamprey Cottus ricei (Greal Lakes) Hybognathus nubila (Western) Uranidea kumlienii (Great Lakes) Long nosed dace (rare in Illinois) Hat headed chub ( Western i Mississippi strip (3): , -hologaster papilliferus (subterranean) Whiti in (rare; Mississippi only i Pigmy sunfish (Southern) Hybognathus nubila (Western) Eupomotis hero', (Southern) Crystallaria asprella (Southern) Etheostoma squamiceps (Southern) GENERAL AND INTERIOR DISTRIBUTION XC111 RELATIONS OF EACH DISTRICT TO ALL THE OTHERS In the foregoing discussions and analyses the fishes of the various districts have been compared with those of the largest and most cen- tral district as a type ; but a fuller and more accurate idea of the com- position of the fish population of Illinois and of its relations in the various hydrographic divisions of the state may be obtained by a comparison of the species of each of our ten districts successively with those of all the others. This may lie done in an exact and uni- form manner by determining for each pair of districts the ratio which the number of species common to the pair bears to the whole number of species occurring within the area of both the districts taken to- gether as one. In the Galena district, for example, there are 44 spe- cies recorded, and in the Saline River basin there are 55, a total of 99 ; but as 26 of these species have been found in both these districts, this number has been taken twice in the above addition, and the number of species found by us in the entire area of these two districts is con- sequently 73. The ichthyological affinity of these two areas is evi- dently to be measured by the ratio which the number of species com- mon to both bears to the whole number of species found in either or both the areas — in this case, the ratio of 26 to 73, or 36 per cent. That is, 36 per cent, of the fishes found in either of these two districts have been found by us in both of them. A similar analysis of the data for each of the forty-five pairs which it is possible to make up from our ten hydrographic districts, yields the material for the following table of common species and of ratios of affiliation. This table shows, in the lower left-hand part, the number of species common to each pair of districts, and in the upper right-hand part the ratios which these numbers bear to the number of species occurring in each pair of districts taken as one. The number of species common to any two districts will be found in the lower left-hand part of the table, where the column for one district intersects with the line for the other, and the ratio of affil- iation for the same pair of districts will be found in the opposite part of the table at the intersection of the line for the first with the column for the second. A simple inspection of the figures in the latter part shows at once which districts are most alike and which are most unlike in respect to their fish inhabitants. Thus, the Rock and Illinois basins and the Mississippi are the most closely re- lated, according to these data, with affiliation ratios of 68-72 per cent, and an average of 70; and the Michigan, Galena, and Big Muddy districts are the least alike, with ratios of 20-28 per cent. FISHES OF ILLINOIS and an average of 23. The two highest single ratios of ichthyo- logical affiliation are those of the Illinois and Mississippi rivers (. 72) and of the Big Muddy and Saline ( . 70). Number of Species Common to each Pair of Districts, and Ratios of such Common Numbers to the whole Number of Species in each Pair Districts a H > £ M o o Pi '8 c s? IS o i§ a .9* % ni (S in -a •a bo S 00 a 13 w at 2 3 o <6 be aj u < 45 89 39 77 60 72 38 47 74 32 68 48 94 68 89 42 53 93 20 35 35 39 25 34 IS 21 38 41 69 72 34 58 73 35 45 79 40 59 53 25 54 66 38 48 59 38 63 66 29 61 66 40 52 76 28 40 33 22 34 52 41 40 40 36 47 41 23 42 63 53 70 51 37 62 68 32 66 53 63 39 49 352 2 . Rock River 42 42 17 41 32 38 19 26 39 542 3 . Illinois River 4 . Michigan .52 283 525 6 . Kaskaskia .517 534 8. Big Muddv 398 9 . Saline River 471 10 . Cairo 521 Total species 44 92 128 57 97 69 95 42 55 101 Number of collections 13 73 1115 20 57 41 103 10 18 95 The data of this table may be generalized by bringing into com- parison the average of the ratios of affiliation for each district with those for all the rest, as shown in the column of figures farthest to the right. If the ten districts are arranged in the order of the size of their average ratios, they readily fall into two groups, the first of six districts, with relatively high ratios, and the second of four, with relatively low ratios. The first group comprises the basins of the larger rivers — the Mississippi, the Rock, the Illinois, the Kaskaskia, the Wabash, and the Ohio, each with its more or less complex system GENERAL AXD INTERIOR DISTRIBUTION XCV of tributaries. The average ratio for this group is 52.7 per cent. The second group is made up of small, widely separated districts, containing only small streams and lakes, except that one of them in- cludes a little of the shallow southwestern border of Lake Michigan. In this group are the northwestern driftless area, the Saline River and its tributaries, the Big Muddy district, and the Michigan dis- trict, with an average affiliation ratio of 37 .6. If we average separately, for these groups, the ratios of each dis- trict to all the other districts of its group, we obtain for the first and higher group a ratio of mutual affiliation of 63 per cent., and for the lower group a similar ratio of 33 per cent. It is thus made clear that the districts most typical of our Illinois fauna are the first six above mentioned, while those most individual and peculiar — least closely affiliated among themselves and each with all the others — are the Michigan, the Galena, the Saline, and the Big Muddy dis- tricts, excepting only the relation of the two last mentioned which, as already said, is unusually close. THE FISHES OF NORTHERN, CENTRAL, AND SOUTHERN ILLINOIS If mere difference in latitude, involving a climatic difference within a range of five and a half degrees, limits the distribution of any of our fishes, the fact should appear upon a comparison of the species list of the northern, central, and southern sections of the state, although due caution must, of course, be exercised that other and more local causes are not confused with climatic ones. The division of the state here adopted is shown on Map II. of the accompanying set. The fishes of these three divisions number 119 species for northern, 123 for central, and 119 for southern Illinois, respect- ively. Fourteen species have been found by us only in the northern division, 9 only in the southern, and 5 only in the central, and 89 spe- cies are found in all three sections. Twelve species occur in both northern and central Illinois, but not in southern, 17 in both south- ern and central Illinois, but not in northern, and 4 in both the north- ern and southern divisions of the state, but not in the central. FISHES OF ILLINOIS Fishes of Limited Distribution in Illinois Illinois Distribution General Distribution Species Peculiar to Northern Illinois Whitefish Great Lakes Lake herring ,, Lake trout .. Long-nosed sucker Northern Notropis anogenus " N . phenacobius N . pilsbryi Southern Great Lake catfish Northern Muskallunge " Brook stickleback " Nine-spined stickleback •• Hadroptcnts cvides Rather general Coitus ricei Great Lakes Uranidca kumlien ii .. Species Peculiar to Southern Illinois Harelipped sucker Southern Long-nosed dace General; rare in Illinois Flat-headed chub Western Chologaster papilliferum Local; cave Pigmy sunfish Southern Round sunfish " Eupornotis heros ■■ Hadroptcnts Ouachita •■ Etheostoma obeyense " Species in Northern and Central Illinois, but not in Southern Lake carp Northern GENERAL AND INTERIOR DISTRIBUTION Fishes of Limited Distribution in Illinois — concluded Illinois Distribution General Distribution Notropis cayuga General N . rubrijrons " Hybopsis hyostomus •■ Stonecat Northern and southwestern Pike Northern Menona top-minnow " Trout-perch ■• Lepomis ischyrus Sauger General Yellow perch Northern Burbot Great Lakes Species in Southern and Central Illinois, but not in Northern Paddle-fish General Shovel-nosed sturgeon " Alligator-gar Southern Mooneye Northern Black-horse General Ericymba buccata " Silver chub " Blue cat Southern Ictalurus anguilla " Freckled stonecat " Brindled stonecat General Viviparous top-minm iw Southern Lepomis symmeiricus " Cottogaster shumardi General Green-sided darter " Etheostoma squamiceps Southern (g) xcvm FISHES OF ILLINOIS An examination of the general distribution of the species of these sectional lists of Illinois fishes shows, as was to have been expected, that the distinctively northern Illinois fishes are chiefly northern in their outside range, and that those of southern Illinois are mainly southern. Thus, of the 14 especially northern Illinois fishes, 1 1 are northerly in their general distribution and 1 is southerly ; while of the 9 distinctively southern Illinois species, 6 are southerly in their gen- eral range, 1 is western, and 1 is a cave-fish local to Illinois. The species found in the northern and central sections of the state and not in the southern are varied in their distribution, 6 of them ranging northward from Illinois, and 4 of them in all directions, while 1 has been thus far found in Illinois only. The central and southern fishes, on the other hand, comprise 7 southern species, 1 of northern and 8 of general range, and 1 whose distribution is not recorded. Includ- ing only species whose general area shows that their restricted occur- rence in Illinois is a feature of their geographical distribution at large, and excluding fishes special to the Great Lakes,we have twenty- six species whose distribution in this state seems limited by condi- tions connected with differences in latitude merely — twelve of these species essentially northern and fourteen of them southern. Especially Northern Species in Illinois (16) : Whitefish Lake herring Lake trout Long-nosed sucker Lake carp Noiropis anogenus Great Lake cattish Mooneye Pike Muskallunge Menona top-minnow Brook stickleback Nine-spined stickleback Trout-perch c 'ottus > i, i i I Wanidea kumlienii Especially Southern Species in Illinois (14) : Alligator-gar Blue cat Ictaluriis anguilla Freckled stonecat Harelipped sucker Notropis pilsbryi Viviparous top-minnow Pigmy sunfish Round sunfish Lepomis symmetricus Eupomotis heros Hadroptcrus ouachitai Etheostoma oheyense E. squamv. eps USE OF LOCALITY MAPS In the foregoing discussion of the sectional distribution of Illinois fishes no account has been taken of differences in the frequency of the occurrence of the species in Hie different sections in which they have been found, a single occurrence in southern Illinois, for example, counting for as much as fifty such occurrences in the northern pari of the state. That highly interesting and important peculiarities of GENERAL AND INTERIOR DISTRIBUTION XC1X distribution are concealed by this gross method of comparison is made evident by an examination of the maps of the distribution of our collections of the various species accompanying this report, where the data are presented in a way to show, not the number of collec- tions, it is true, in which each species was represented, but the number and distribution of localities from which the species has been obtained. From such a study of these maps it appears that the northern half or two thirds of this state is more favorable to a considerable number of species than the southern part, since these species have been taken there in a much larger number of localities ; and also that a small group of species of wide general distribution has been found by us with surprising frequency in the Wabash drain- age in this state as compared with that of adjacent districts. The preference of certain species for the northern part of Illinois over the southern is clearly illustrated by the distribution maps of the following fifteen species: Noturus flavus, Carpiodes thompsoni, Notropis cayuga, N . hudsonius, N. rubrifrons, Hybopsis dissimilis, H. kentuckiensis, Fundulns diapliauus, Percopsis guttatus, Eupomotis gibbosus, Stizostedion canadcnse, Pcrca ftavescens, Etheostoma zonale, Roccus chrysops, and Morone interrupta. With few and slight excep- tions, all the species of this varied list, representing eight families and twelve genera, are so definitely limited to the northern half of this state that one gets the impression, as he examines these maps in succession, that some invisible barrier to their southward dispersal exists in the neighborhood of the Sangamon River. PECULIARITIES OF DISTRIBUTION IN THE LOWER ILLINOISAN GLACIATION That the distribution of these more northerly species is not lim- ited by the watersheds is shown by the fact that they range across the state indifferently into all the stream systems of northern Illinois. It is not until we compare with our distribution maps a map of the surface geology of the state (Map III.) that we find a plausible ex- planation of a part, at least, of this peculiar distribution, for all but one of the species above mentioned are wholly excluded from the area of this glaciation, and this excepted species (Hybopsis dissim- ilis) appears in but one locality within the lower glaciation, and that a short distance within its border, on the upper Kaskaskia. Especially significant in this relation are several cases in which species of this list range southward in the eastern part of the stale upon the upper tributaries of the Kaskaskia and the Embarras, for in so doing they simply follow southward the course of the Shelby- ville moraine which forms the boundary between the Wisconsin and C FISHES OF ILLINOIS the lower Illinoisan glaciations in east-central Illinois. The maps for Noturus flavus, Hybopsis dissimilis, H. kentuckiensis , and Stizo- stedion canadense are examples. That this coincidence of distribution and surface geology points to a true explanation is further shown by the maps for twenty-two other species which range more definitely to the southward than the foregoing twelve, but which nevertheless avoid the southern glacia- tion more or less completely and to an unmistakable degree. For example, 19 of our 94 collection localities for the hogsucker (Catos- tomus nigricans) lie below the Springfield parallel, but only three of them are in the lower Illinoisan glaciation, and these are barely within its borders. Of our thirty localities for the short-headed red- horse (Moxostoma breviceps) only two are in this glaciation, and these are near its boundaries on the Embarras and the Kaskaskia. The very abundant minnow Campostoma anomalum was taken by us from one hundred and sixty localities, thirty-one of which are south of the Sangamon and eight of them from the non-glaciated area of the Cairo district, but only one of the entire number is within the lower glacia- tion, and that is on the upper Kaskaskia just across the limiting mo- raine. The map for Notropis cornutus shows one hundred and sixty- one localities from which collections of this species were made, ninety of them below the Sangamon and twenty-nine in the Cairo district, but only three are in the southern glaciation. Other species testify- ing to the same effect will be found in the following list of fishes ab- sent from this characteristic southern Illinois district. Illinois Fishes Rare or wanting in the Lower Illinoisan Glaciation Short-nosed gar A', rubrifrons Common bullhead Spotted shiner Stonecat Storer's chub Lake carp River chub Quillback carp Pike Common sucker Menona top-minnow Hogsucker Trout-perch Short-headed red-horse Pumpkinseed Stone-roller Small-mouthed black bass Red-bellied dace Sauger Notropis cayuga Yellow perch N . heterodon Banded darter Straw-colored minnow Rainbow darter Notropis gilberti Fan-tailed darter S|» it -tailed minnow White bass Common shiner Yellow bass Notropis jejunus Miller's thumb general and interior distribution ci Fishes Tolerant of the Lower Illinoisan Glaciation' Dogfish Silver chub Channel-cat Grass pike Yellow bullhead Common top-minnow Black bullhead Viviparous top-minnow Mud-cat 1 'irate-perch Tadpole cat White crappie Brindled stonecat Round sunfish ( hub-sucker Warmouth Striped sucker Green sunfish Silvery minnow Long-eared sunfish Blunt-nosed minnow Orange-spotted sunfish i fpsopceodus emilitE Large-mouthed black bass Golden shiner Black-sided darter Bullhead minnow Boleosoma camitrum Silvertm Sand darter Shiner Etheostoma jessia Blackfin Boleickthys fusiformis Ericymba buccata Among the ninety-six Illinois species for which distribution maps have been prepared, thirty-four belong clearly to this group of fishes which seem to avoid the conditions common to the flat gray lands of the southern part of the state. Thirty-five species, on the other hand, are distributed over this glaciation in a way to indicate a tol- erance of its conditions if not an indifference to them, the data con-, cerning the remaining thirty-three species being ambiguous or inde- cisive in this respect. Two facts concerning the soil and waters of the lower Illinoisan glaciation may be held to account, at least in part, for the failure of certain species of fishes to thrive in its streams. Compared with the other regions of the state, this oldest of our glaciation areas has de- veloped its drainage system to a point such that the rainfall runs off rapidly in a large number of small streams, leaving no marshes or ponds to hold back the waters during periods of dry weather. It is a level country whose streams fill up quickly and run down rapidly, the smaller ones drying up completely during the midsummer drought, which is here more marked than farther north. These variable and temporary creeks are, of course, less favorable to the maintenance of a varied and permanent fish population than the waters of the earlier Illinoisan or the Wisconsin areas. As a further consequence of its geological antiquity, involving degenerative chemical changes and a long-continued leaching, the soil of this lower glaciation has become an extremely fine-grained, light-colored clay which, when compact, sheds water almost com- pletely, but which washes into the streams as a fine detritus that re- mains persistently in suspension and renders the waters very turbid for a long time after a rain. Standing pools, indeed, never become Cll FISHES OF ILLINOIS even approximately clear. So persistent is this turbidity, due to very finely divided matter in suspension, that the chemists of the Water Survey find it almost impossible to free the water wholly from suspended solids even by repeated filtration. Furthermore, this soil has a definitely acid reaction, to which is due a notable physical dif- ference between the soils of this area and those of the later glacia- tions west and north of it. A surplus of lime in a soil coagulates or granulates it, causing its ultimate particles to cohere in larger gran- ules, while in an acid soil this effect is entirely wanting. This lack of granulation in a very finely divided soil increases, of course, the per- manent muddiness of its waters as compared with those of the other areas in which lime in the soil renders it alkaline. The acidity of this southern soil seems not to be of a kind or amount to affect the surface waters sensibly and directly, since the water samples from this region analyzed by the State Water Survey show a soft water, slightly alkaline, and chemically unobjectionable as a medium for fishes. CLASSIFICATION AND USE OF ECOLOGICAL DATA That these conditions are a part, at least, of the cause of the phe- nomenal distribution of southern Illinios fishes may be shown by a comparison of our ecological data for the fishes of the two lists — one composed of those adapted to the conditions of the lower Illinoisan glaciation and the other of those avoiding them. In the organiza- tion of the data of our collections of Illinois fishes, those concerning the character of the water body in which collections were made were classified in a way to show the number of collections of each species taken from each class of situation. By reducing these numbers to ratios of frequency of occurrence, we have a means of exhibiting the preference of species with respect to the situations in which each oc- curs. Pimephales notatus, for example, was found twenty times over a muddy bottom to thirty-four over a bottom of mud and sand , and to forty-six over a bottom of rock and sand. Aphredoderus sayanus, on the other hand, was found sixty-two times on a muddy bottom to nineteen times in each of the other situations. By tabulating data of this description separately for each of the two lists of species referred to — thirty-four species in the one list and thirty-five in the other — and averaging the ratios for each group separately, significant evidence was obtained of the factors which afreet the distribution of these fishes. The species which distribute themselves freely over sou f hern Illi- nois are those which are generally tolerant of turbid waters, as shown GENERAL AND INTERIOR DISTRIBUTION Clll by the fact that 32 per cent, of all our collections of this group came from muddy streams and ponds, 34 per cent, from situations where the bottom was composed largely of rock and sand, and 24 per cent. from a bottom of sand and mud. The species avoiding the central area of southern Illinois, on the other hand, are, as a rule, intolerant of muddy waters, only 10 per cent, of all our data-bearing collections of this group coming from such situations, while 61 per cent, of them were from bottoms of rock and sand, and 29 per cent, from those of sand and mud. It is consequently clear that the suspended detritus of the streams of southern Illinois and the clay and mud of which their banks and bottoms are commonly composed, are an important part, at least, of the cause of the smaller variety of fishes in these waters ; and these conditions trace back through the character of the soil to the geological history of the central part of southern Illinois. FISHES OF THE OHIO AND OF THE MISSISSIPPI DRAINAGE A comparison and classification of our distribution maps from another point of view enables us further to distinguish two rather definite groups of species coincident in great measure, but not wholly so, with the two groups which we have found in an opposite relation to the lower Illinoisan glaciation. No less than 27 of our species have either an exclusive, or at least a strongly preponderant, dis- tribution in the Mississippi drainage in the western and northern parts of the state, while 8 species, on the other hand, are very defi- nitely preponderant in the Ohio drainage in the southern and eastern parts. Nineteen of the 27 species of the first list are also on the list of species excluded from the region of the lower Illinoisan glaciation, while 6 of the 8 species of the second list are also on that of species dis- tributed freely through this southern Illinois district. We have evi- dence here of another influence strongly affecting distribution, coin- cident in part with that already discussed, but independent of it also in part, the two causes, or sets of causes, operating together to deter- mine the actual range of most of the species of limited distribution in this state. The impression produced by an examination of the two sets of maps for the fishes above mentioned, is that of a small group of spe- cies, on the one hand, which enter the state from the south and east by way of the Wabash and the smaller tributaries of the Ohio, and, on the other hand, of a much larger group, most of which have en- tered the state from the west and north, making their way to its in- terior mainly by the Illinois and the Rock, but sometimes by the CIV FISHES OF ILLINOIS Kaskaskia and the Big Muddy also. Species of the Ohio group sometimes seem to spread into the headwaters of adjacent streams, especially into the branches of the Kaskaskia where these come near- est to the Embarras, and into those of the Big Vermilion of the Illi- nois which are nearest to the Little Vermilion of the Wabash. Some species, however, remain carefully within the tributaries of the Wa- bash system. It seems possible that this appearance of an approach to the state and entrance upon its territory from opposite directions is not alto- gether deceptive, and that the annual movements of the fishes of the state, up the streams at the time of the spring floods, downwards with the recession of the waters, and still farther downwards, for many species, into deeper water in the winter, may take these two contingents of our fish population in opposite directions, from and towards local centers of population for the species, situated on oppo- site sides of the state. Whether and where such local centers of population actually exist, is a question which can not be answered definitely for lack of numerical or statistical data in the faunal lists and other literature of geographical distribution for the sur- rounding states. If they exist, the Wabash fishes would constitute one such system, and those of the Mississippi and its tributaries, another. If we may speculate still further upon this subject, we may per- haps surmise that a general critical analysis of the fish population of the larger area of which Illinois forms the central part, would enable us to distinguish fairly well-defined districts, each with its charac- teristic assemblage of prevalent species, so associated and ecologic- ally related as to form a balanced assemblage of species, all so ad- justed to each other and so advantageously placed in their environ- ment as to constitute a closed system, which the characteristic species of adjacent areas can not enter, or in which they can not permanently remain. Distribution chiefly in the Ohio Drainage Brindled stonecat Pirate-perch Green-sided darter Notropis illecebrosus Boleichthys fusiformis Ericymba buccata Chub-sucker Long-eared sunlish DlSTKIUI riON CHIEFLY IN THE MISSISSIPPI DRAINAGE Short-nosed gar White bass Stonei at Yellow bass Lake carp Common bullhead Notropis cayuga Short-headed red-horse GENERAL AND INTERIOR DISTRIBUTION < V Spot-tailed minnow Red-bellied dace Notropis rubrifrons Notropis gilberti Spotted shiner Long-nosed gar Pike Dogfish Menona top-minnow Mongrel buffalo Trout-perch Black-head minnow Pumpkinseed Hybognathns nubila Sauger Redrin Yellow perch Rock bass Banded darter BOUNDARY BETWEEN NORTHERN AND SOUTHERN SPECIES Recurring next to the distinction made on another page (xciv) 1 >e- tween northern and southern fishes whose areas extend into Illinois but not beyond, and comparing the distribution of these groups within the state, as given on Map CIII., we see that northern and southern species meet and mingle in the western part of the state from Meredosia to Pekin on the Illinois, and from Quincy to Dallas City on the Mississippi, but that in eastern Illinois they are separated by a wide interval extending from Cook county to the mouth of the Embarras, in which interval we have never taken any representative of either group. The distinctively southern species, although most abundant south of the line 28° 30", nevertheless go up the Wabash to the Em- barras, up the Kaskaskia to Shelby county, up the Mississippi to Henderson county, and up the Illinois to Pekin, also following the branches of the Sangamon to Logan county. The northern species, on the other hand, although most abundant above 40° 20", come down the Illinois to Meredosia, and down the Mississippi to Quincy. The boundary between the northern and southern species thus appears as a broad belt some fifty miles in width, extending two thirds of the way across the state just above its center, but widening to a distance of one hundred and seventy-five miles on the eastern boundary. GENERAL FEATURES OF ECOLOGICAL DISTRIBUTION In addition to the general distribution of Illinois fishes over the North American continent, their general or partial distribution within the state, and the unevenness of their distribution over the different divisions of the state, hydrographic, climatic, and geolog- ical, there are also recognizable differences and inequalities of dis- tribution corresponding to the size of the water bodies in which the species are found, to the nature of the bottom and the consequent clearness and purity of the waters, and to the existence and rate of current or flow in the waters inhabited by them. In this class of FISHES OF ILLINOIS divisions, geological distribution merges into ecological relation, the distribution of species being no longer by geological areas, but by ecological situations. In this sense two species may occupy pre- cisely the same territory without ever coming into any effective con- tact with each other, because they are differently related to certain features of their environment. As an explanation of the more general facts of distribution re- quires an analysis and interpretation of continental, terrestrial, and even cosmic agencies affecting it, so an understanding of what we may call the ecological distribution of a species, requires a corre- sponding analysis of the ecological features of the region. Such an analysis can here be carried but a little way, since the ecological data borne by our collections are only of a very general type ; but such as they are, they may, if used with discretion, add definiteness and de- tail and some degree of satistical precision to our knowledge of this part of the subject. The attention of the reader is called especially to the interesting manner in which our statistics of associate occurrence exhibit the frequent tendency of closely allied species inhabiting the same terri- tory to avoid each other's company, and thus to evade competition with one another, by the choice of different haunts and situations within the area of their common habitation. In consequence of this tendency, we sometimes find widely unlike species more closely and commonly associated in our collections than like, the ecological repulsion of each for its similars bringing dissimilars together in more or less definite associate groups. Apparent examples of this reaction may be found in the body of this report in the discussion of the suckers, the minnows, the catfishes (especially the bullheads), the top-minnows, and the sunfishes. Ninety-seven of our species have been collected in large enough numbers, and from a sufficient variety of locations, to give us data for comparison with reference to the general character and size of the water bodies which they prefer; 62 species furnish available data concerning the bottom or substratum of these water bodies; and 49 species, data concerning current and rate of flow. The numbers of collections for the various species covered by these figures vary greatly from a minimum of 10 collections of a species to a maximum of 376. Unfortunately, the larger and more important fishes are commonly represented by the smaller numbers of collections, and statements made concerning these arc less likely to be found fairly accurate anil generally correct than are those concerning the smaller fishes, represented by larger numbers of collections. GENERAL AND INTERIOR DISTRIBUTION CV11 One available set of our data may best be presented in tabular form, for such use as the student may wish to make of them ; and to this table we add, as an illustration of its use, only a few statements concerning the more conspicuous ecological groups of our Illinois fishes. By assorting the species according to the size of the ratios of fre- quency of occurrence for each class of situations distinguished in this table, we may separate those strongly preferring the given situa- tion from those apparently avoiding it. In this way we learn that the species occurring in our collections with disproportionate fre- quency in the larger rivers of the state are the mud-cat (Leptops oli- varis), one of the river carp (carpio), the toothed herring {Hiodon tergisits), and the sheepshead (Aplodinotus) , among the larger fishes ; and a small darter (Cottogaster shumardi) , the trout-perch (Percopsis guttatus), and a minnow (Hybopsis dissimilis) among the smaller fishes. The principal larger fishes of the smaller rivers make a much longer list, comprising the hogsucker, two of the native carp {veli- fer and difformis), a species of red-horse (aureolum) , the rock bass, and the small-mouthed black bass; and the principal smaller species are six darters (Ethcostoma zonale, Hadropterus phoxocepha- lus, H. as pro, Diplesion blennioides , Etheo stoma casruleum, and Am- ■mocrypta pellucida), a stonecat (Noturus flavus), and Hybopsis kentuckiensis , and four other minnows, all of the genus Notropis (rubrifrons, gilberti, blennius, and comutus) — their ratios running from 70 per cent, for rubrifrons to 41 per cent, for comutus. The species of our list which have from 50 to 100 per cent, of their representatives in creeks, as illustrated by our collections, in- clude three sunfishes (the green sunfish, the round sunfish, and the long-eared sunfish), three suckers (the common sucker, the chub- sucker, and the striped sucker1), four darters, ten minnows, and the brindled stonecat. The larger species found most abundantly in lakes, ponds, and other stagnant waters were the common bullhead, the buffaloes, the yellow perch, the white bass, the yellow bass, the large-mouthed black bass, and five sunfishes (both crappies, the warmouth, the pumpkinseed, and the bluegill) ; and the smaller kinds were the smallest of our fishes (Microperca punctulata) , another darter (Bole- ichthys jusiformis) , two minnows {Notropis cayuga and N. hetcrodon) , the mud-minnow, and a killifish (Fundulus dispar). Turning next to the 62 species for which our data of preference < >r avoidance of a muddy bottom are available, we find 7 species whose cviii FISHES OF ILLINOIS ratios of frequency of occurrence in such situations range from 43 to 88 per cent., and which may consequently be called limophagous fishes. These are the warmouth sunfish, the black and the yellow- bullheads, the pirate-perch, a single darter (Boleosoma camurum), and two minnows, the golden shiner and the common shiner (No- tropis cornutus. ) It is interesting to find, by an examination of our maps, that all these 7 species are freely distributed over the lower Illinoisan glacia- tion of the southern part of the state, where, as we have already shown, only fishes indifferent to a peculiarly persistent turbidity of the water are likely to occur. By selecting from this same list of 62 species those with the lowest ratios of frequency over a muddy bottom, we get 13 species (with ratios of 4 to 10 per cent.) which evidently avoid such situations; and these, again, are without exception so distributed that the area of the lower Illinoisan giaciation is almost never entered by them. These are one of the native carp (velifer), a species of red-horse (aure- olum) , the small-mouthed black bass, two darters (Hadropterus phox- ocephahis and Etheostoma coeruleum), five minnows (Campostoma anomalum, Notropis heterodon, Ericymba buccata, Hybopsis kentuck- iensis, and Notropis blennius), two stonecats, and the little brook sil- verside (Labidesthes). A more precise statement and a fuller discussion of the ecological relations of our fishes, including statistics of companionship for the various species, as shown by the frequency of their joint occurrence in collections, must be left for later contributions. Attention may be profitably called, in conclusion, to the econo- mic significance of the details of distribution of the various species, as influenced both by geographical and ecological conditions, since a proper understanding and application of these facts will prevent wasteful efforts to introduce species where they do not belong and can not thrive. Indeed, the more detailed our knowledge of favor- able, and even optimum, conditions for the different species, and the more exact, also, our acquaintance with the relations of each species of fish to its companion species in any associate assemblage, the more intelligent, and hence the more successful, in the long run, will be our efforts to extend the range and multiply the numbers of the more useful species and to lessen the numbers of those espe- cially injurious. GENERAL AND INTERIOR DISTRIBUTION C1X ECOLOGICAL TABLE ALL ILLINOIS SPECIES WITH AT LEAST TEN AVAILABLE RECORDS EACH* 03 o Water (97 species) Current (49 species) Bott om (62 species) is a c S a > W •d c id § •a u 0 1—1 Species a q '■*-> o "o o _2 '3 > E U) *-< tS u u > 'u u a & AS u U o +j in ■d a o a w a) B ■B o _4j "3 < 2 V •a o s o +-» en c a be cd -t-» w O 'So 55 .3 > 1 o 0) o o JU '3 > < ■a a •a 5 -a c a) o o Pi a w •a a ca 3 1 S 1 Long-nosed gar Short -nosed gar Dogfish 35 ?5 19 7 22 ts? 57 ^7 28 18 24 7 4 A 25 so tss 207 171 122 20 7 32 6 27 37 8 23 31 14 68 36 19 43 13 -'1 7 5 35 21 43 44 34 35 215 Yellow bullhead 23 217 Common bullhead Black bullhead 4S 244 15 8 5 21 4 37 44 26 218 38 37 53 10 56 54 46 221 Mud -cat . 30 41 193 30 39 19 53 10 17 3 13 17 21 53 5 36 5 34 23 60 9 7 8 41 ??? 15 21 48 13 43 26 9 24 45 13 8 29 8 58 27 62 34 223 44 ?31 Brindled stonecat Red-mouth buffalo. Mongrel buffalo Small-mouth buffalo . . River carp 30 ?61 - 45 ?6? ?64 52 1 5 14 4 7 12 4 8 49 10 ?65 266 Blunt-nosed carp 102 9 42 30 12 16 50 25 25 47 21 36 43 268 70 10 50 19 5 19 47 32 21 28 4 60 36 289 132 3 19 71 1 1" 39 47 14 7" 13 44 43 294 Hogsucker 99 4 63 ?5 4 71 ?0 63 17 59 54 46 302a Chub-sucker 131 9 12 57 1 1 23 52 48 57 32 39 29 ♦The figures of this table, except ratios of frequency of the species in comparative numbers of collections of those in the columns for available collections, are our collections, computed with due reference to the all kinds made in each situation ex FISHES OF ILLINOIS ECOLOGICAL T ABLE— continued ALL ILLINOIS SPECIES WITH AT LEAST TEN AVAILABLE RECORDS EACH w O Water (97 species) Current (49 species) 3ottom (62 species) a a a B > H d c3 c a! ■d Vh O l—l Species C O o 0) "o o a> _cd '3 > < U > V CD u u a! w u > 'u u s en A! < s •d o s o +-> +J > a c be to O -M JS E/J 'Si M 53 cs > C o u V JS '3 > < •d 3 *d a a! CO ■a c « CJ O •d a in •d a cS T3 303 Striped sucker 46 2 31 53 ? 19 76 3? 4? 305 18 7 44 20 (, 314 Common red-horse. . . . 143 9 32 40 4 47 57 28 15 65 6 55 39 319 55 13 25 15 1 > 14 14 43 43 328 195 93 3 10 37 55 71 1 65 63 23 14 105 7 5 7 36 334 340 Silvery minnow 183 12 36 32 7 30 47 40 13 67 33 40 27 349 Black-head minnow. . . 95 14 30 48 4 12 50 42 8 44 25 41 34 350 Blunt-nosed minnow. . 376 5 34 43 12 108 50 34 16 202 20 46 34 355 Horned dace 151 4 28 63 2 42 48 36 16 81 17 47 36 391 Opsopccodus emilice. . . . 40 13 6 36 32 394 303 12 17 29 32 28 32 57 11 82 44 29 27 398 Bullhead minnow 187 17 31 28 7 36 67 17 16 62 11 44 45 405 29 13 26 57 13 54 38 8 15 27 73 406 92 185 1^ 7 1 44 19 37 60 3 14 103 7 in 22 50 71 408 Straw-colored minnow. 63 49 26 25 40 420 Notropis gilberti Notropis illecebrosus . . . Spot-tailed minTii ,.■.. Redfin 30 2 49 43 2 IS 11 45 44 426 11 147 100 2 428 432 28 5 39 .... in ?n 80 163 24 32 20 14 13 46 38 16 55 27 40 33 448 Silvertin 268 6 39 40 4 65 54 26 20 126 ■ 3 56 31 GENERAL AND INTERIOR DISTRIBUTION CXI ECOLOGICAL TABLE — continued ALL ILLINOIS SPECIES WITH AT LEAST TEN AVAILABLE RECORDS EACH Species Water (97 species) Current (49 species) Bottom (62 species) o ■z c 9 s u > a •d B 3 C a ■d V- O a o +3 CJ JU "o o 3 '3 > < E > 'u u 9 6? u > u Ji e en CO CJ a V c/f ■o c o a w V -a ij C .o O _aj "o o V 6 w 'So bo _3 55 3 c ai > w B O +3 o ^ "o o < 13 ■d a aj v. ■d a ni M o o P4 -d 5 3 in •d C •d 3 2 27 20 4 3 1 5 50 5 21 4 16 17 7 7 41 19 36 70 32 18 36 27 29 32 41 50 13 15 26 65 81 53 22 66 11 51 4 11 76 45 36 19 102 12 48 11 100 38 92 44 25 21 17 8 15 48 67 64 82 43 63 51 8 8 485 489 498a Shiner Notropis rubrifrons. . . . 20o 13 70S 11 1 23 11 69 14 53 57 45 41 43 53 30 IS 45 29 24 13 36 14 28 23 14 18 40 499 501 Ericymba buccata Sucker-mouthed min- 74 159 11 41 29 34 528 Spotted shiner 533 10 1 16 20 49 30 49 72 12 12 19 13 77 15 7 20 SO 55 15 534 536 River chub 129 674 Toothed herring . 10 677 C\vvnT(\ sh.nrl . 10^ 55 53 24 23 74 8 43 49 32 24 16 7 8 34 42 3 49 32 4 22 23 55 27 919 922 34 11 1 17 83 208 17 15 1 1 36 57 7 29 38 21 41 939 Menona top-minnow . . Striped top-minnow. . . Common top-minnow . Viviparous top-minnow 966 11 6 12 52 25 21 967 100C 34 41 50 9 81 32 42 26 1145 CX11 FISHES OF ILLINOIS ECOLOGICAL TA BLE — continued ALL ILLINOIS SPECIES WITH AT LEAST TEN AVAILABLE RECORDS EACH Water (97 species) Current (49 species) Bottom (62 species) o c 01 1) > H ■a c a! C cs •a 0 Species o OJ "o o a > < u 1) > 'C u u M E en o ID w" c 0 p. cS .i. a o '■P "o o < 01 2 •a o £ o ■*-> *-> c ni C M ca w o -C w 'So to 'C > C O o "o u I ni > < D T3 C a! w C nl u O Pi 73 C al w •o C a) T3 3 s 1147 100 IS 5 42 21 14 21 72 7 37 62 19 19 1177 Brook silverside 120 13 28 13 36 16 31 44 25 21 10 62 28 1381 White crappie 166 15 1" 17 34 14 64 29 7 43. 35 49 16 US' Black crappie 170 17 16 10 42 28 25 50 25 1383 Round sunfish Rock bass 11 48 69 ?4 30 1 3 1385 7 40 ">0 55 15 30 ?7 48 5"> 1387 Warmouth 122 313 12 7 17 12 57 45 1 1 17 156 88 ?8 12 41 13Q1 Green sunfish sn W 45 16 T1 13Q7 Lepomis miniatus Long-eared sunfish. . . . 23 112 in 2 12 11 76 41 4 1399 17 41 47 12 41 37 63 1400 Orange-spotted sunfish 174 12 25 34 20 21 38 38 24 60 30 35 35 1403 Bluegill ?14 16 in 7 54 ?4 ?5 58 17 1408 Pumpkinseed s5 6 17 4 5(5 1409 Small-mouthed black bass inn 6 43 ?3 16 40 55 18 ?7 50 6 68 ?6 1410 Large-mouthed black bass 211 36 16 83 60 8 16 36 20 10 20 10 7 38 17 8 4 3 27 40 33 25 51 1') 19 58 26 16 48 19 54 27 1413 Pike-perch 1414 141 S 1417 Log-perch 1 1 93 7 20 100 GENERAL AND INTERIOR DISTRIBUTION ECOLOGICAL TABLE— concluded ALL ILLINOIS SPECIES WITH AT LEAST TEN AVAILABLE RECORDS EACH 0 Water (97 species) Current (49 species) Bottom (62 species) 'A c c a S > W •o c CS c •o u 0 <—• Species C o u 3 3 '3 > < w u > 11 be u C3 u > u H 5 w in V. u •a c 0 p< to" a 0 '-£ 0 QJ 3 O 3 '3 > a) +-< 2 ■a 0 £ 0 +^ '% c nj C U) n! O +-» 43 w 'S3 U) 3 ■c a! > C u a> 0 0 01 3 gs '3 > < •a c -a c a! O -a a in a a 1418 Hadroplcrit s pin >.v. >ceph- alits ss 7 57 ^7 3 37 87 H 48 6 94 1421 Black-sided darter. . . . 159 6 42 47 1 4" 70 30 76 16 84 1436 Cottogaster shwmardi. . . 16 24 234 55 3 46 25 4 53 53 18 1443 Green-sided darter. . . . 1446 fohnny darter 16 71 68 32 126 1 1 89 1448 Boleosoma camurnm . . . 107 9 23 42 17 17 41 59 39 60 40 1450 Sand darter 19 32 13 3 47 74 39 23 1461 Banded darter 18 89 11 19 11 89 1474 Etheostoma jessice 158 20 19 16 24 12 83 17 31 23 67 1477 Rainbow darter 80 3 44 45 1 29 83 17 37 8 92 1489 Etheostoma squamiceps 1490 Fan-tailed darter 10 30 56 12 56 100 57 9 1 35 12 64 87 24 4 8 1 4 62 95 46 52 27 11 21 33 100 67 1494 Boleichthvs iusiformis . . 1497 1529 1531 . . . . White bass 28 20 29 4 16 Yellow bass 1871 (h) FISHES OF ILLINOIS GENERAL SUMMARY. The principal conclusions of this chapter may be thus sum- marized : 1 . The 150 native species of Illinois fishes here recognized, are so distributed within and without the state as to indicate an unequal commingling of the faunae of the surrounding territories, southeast- ern species preponderating over southwestern, northeastern over northwestern, eastern over western, and southern over northern. 2. The Illinois basin may be taken as typical, in its fish popula- tion, of the ichthyology of the whole state — occupying, as it does, a central position, including more than half the area of the state, and containing a great variety of waters and situations fit for the habita- tion of fishes, and more than four fifths of the species found anywhere in Illinois. The more important fishes of the state not known from this basin are a few distinctively northern species, most of which are peculiar to the Great Lakes, and a few southern species which do not range as far north, in this state, as the mouth of the Illinois. The remainder are very rare in our territory, most of them coming from the west and south, and they are extremely insignificant elements of our fish fauna. 3 . If the ten stream systems of the state be brought into com- parison one with another, it appears that the six larger areas, con- taining the largest streams and presenting the greatest variety of situations, are much more closely affiliated ichthyologically than are the four smaller areas. The least closely affiliated with each other and with all the rest are the Michigan district of northeastern Illinois and the Big Muddy basin in the southwest. The closest relations are those between the Illinois, the Rock, and the Mississippi. 4. In the absence, in Illinois, of geographical barriers to the dis- persal of fishes, the causes influencing their distribution are climatic, geologic, and ecological. As Illinois extends through 5.5° of lati- tude, differences of climate between the northern and the southern sections of the state are sufficient to affect, in considerable measure, the distribution of its plant and animal species — differences which, in its ichthyology, express themselves in the presence in northern Illinois, hut not in southern, of 17 species of general northward range; and in southern Illinois, but not in northern, of 14 species of general southward range. These two groups of species meet and mingle in the great north and south rivers of the western half of the state, in an area of common occupation about fifty miles in width, from the latitude of Springfield northward; while on the eastern GENERAL AND INTERIOR DISTRIBUTION CXV boundary of the state, occupied bysmall streams of various direction, these groups are separated by an interval of about a hundred and seventy-five miles over which no representative of either group has been taken. 5 . Geological limitations to the dispersal of fishes are illustrated by peculiarities of distribution in southern Illinois as related to the area of the lower Illinoisan glaciation, which 34 species evidently avoid while 35 other species enter upon it freely and inhabit it suc- cessfully. A comparison of the ecological relations of these two groups of species as represented by our collection records, shows that they are strongly distingushed by the repugnance of the first group, and the indifference of the second, to waters with a muddy bottom, collections of the first group having been made from such situations in an average ratio more than three times as great as that for the sec- ond. The waters of this region, on the other hand, are remarkably and persistently turbid, never clearing themselves spontaneously. This is owing in part to the extremely fine division of the soil, and in part to its generally acid character and the consequent lack of "gran- ulation," or cohesion of its ultimate particles in granules, such as oc- curs in the alkaline soils of the other geological areas of the state. The surface waters of the district are soft and slightly alkaline, but con- tain much silica, and much solid matter in suspension which it is ex- tremely difficult to remove completely by any ordinary filtering or precipitation process. The inference is plain that it is to this condi- tion of the waters — due to the geological history of the soil of this region — that the unequal distribution of these fishes is largely to be attributed. 6. In consequence of another clearly recognizable inequality of distribution, partly coincident with the two preceding and partly in- dependent of them, two additional groups may be distinguished; one of 8 species, distributed in this state mainly through the Ohio and Wabash drainage, and the other of 27 species, distributed through the Mississippi and its more northerly tributaries. The general dis- tribution throughout the country at large of each of these two groups of species is quite varied, and offers no hint of a reason for these dif- ferences in Illinois. Two hypothetical explanations are suggested— the first presupposing different centers of population outside the state, from and towards which these species move, into and out of Illinois streams, with the spring rise, summer recession, and winter cooling of the waters, one of these centers to the west and north, and one to the east and south ; and the second presupposing an organiza- tion of the fish population into more or less distinct communities of CXV1 FISHES OF ILLINOIS mutually well-adjusted species, each community so adapted to its environment that members of adjacent communities can not success- fully intrude upon its territory. 7. An analysis of our statistical data of ecological distribution gives us many instances of a marked difference in preference of situation between nearly related species inhabiting the same area, the effect of which is to break the force of a competition between these species such as would prevail if they were similarly distrib- uted ecologically as well as geographically. Closely related species are, as a consequence, often found much less frequently associated in their common territory than either is with widely unlike species of the same geographical range. Exceptions to this rule are found where similar species occupy adjacent areas of distribution which merely overlap by their borders. 8. A table of the broader ecological relations of 97 species of Illinois fishes is made the basis of a few general statements, but that subject as a whole is reserved for more detailed treatment else- where. 3 g •3 c 3 03 O J3 O U o J OS o ►4 ■a a! a, o -a c o J3 THE FISHERIES OF ILLINOIS CXV11 The Fisheries of Illinois Since the state and the nation maintain, in their commissions of fish and fisheries, special agencies for the investigation and promo- tion of economic ichthyology, the Natural History Survey is not con- structively responsible for work in this field. The subject of our fisheries is, however, an essential part of the science of ichthyology broadly considered — a division, indeed, of ichthyological ecology, of which the reciprocal relations and interactions of fishes and men are as legitimate and necessary a part as those of fishes and any other factor of their ecological environment. The economic element has, consequently, been taken into account in our discussion of species and the larger groups, and a brief resume of its principal features is evidently appropriate to this introduction. The distinction of Illinois as a fish-producing state is to be found in its relation to the Mississippi River and some of the most impor- tant branches of that stream. Bordered by the main river for the whole length of its longest side, by the second largest tributary of the Mississippi for 130 miles of its southeastern boundary, and by the Wa- bash for 198 miles on the east, the state is also traversed diagonally by the Illinois River, admirably adapted, by its sluggish current, by the many bottom-land lakes connected with it at low water, by the ex- tensive breeding-grounds afforded to fishes during the period of the spring overflow, and by the vast abundance of fish food in its waters at all seasons of the year, to support an unusually large and varied fish population. Illinois is consequently far in the lead of all the states of the Mississippi Valley in respect to river-fishery products. It markets a larger value per annum in fishes taken from flowing streams than all the states immediately surrounding it taken to- gether. The total for this state in 1899 was $517,420, and that for Iowa, Missouri, Kentucky, Indiana, and Wisconsin combined was $435,137. Illinois furnishes, indeed, more than one third of the fishes sent to market from all the streams of the Mississippi Valley, — valued in 1899 at $1,473,040. Furthermore, the Illinois River and its tributaries produced in 1899, 72 per cent, of all the fishes taken from the streams of the state, and a fourth of the entire fish product of the Mississippi Valley came in that year from this one stream. The totals for the different Illinois stream systems were as follows: CXV111 FISHES OF ILLINOIS Illinois, $371,110; Mississippi, $118,278; Wabash, $38,065; Ohio, $20,029 ; Kaskaskia, $3,002 ; Big Muddy, $1,136. The Great Lake fisheries in Illinois waters are of insignificant pro- portions. The total longshore product for Cook and Lake counties during the last census year was $12,500 — about $2,000 less than the sum derived from our river turtles alone. The river fisheries of the state gave employment in 1899 to 2,389 men, and utilized a capital of $225,000. Sixteen steamboats, 200 house-boats, and 1,500 row-boats were used in these fisheries, to- gether with about 45 miles of seines, 10 miles of trammel-nets, half a mile of gill-nets, and 14,000 fyke-nets, pound-nets, and traps. The seines and the fyke-nets together yielded about 80 percent, of the prod- uct, the seines bringing in $2 5 1,5 62 and the fyke-nets $2 10,054. Set- lines yielded $3 7 , 1 9 1 ; trammel-nets, $24,185 ; traps, $2,707 ; gill-nets, $1,290; drift-lines, $1,141; pound-nets, $811; and hand-lines, $701. The dozen most productive kinds of Illinois fishes, according to the statistics of the last census year, were as follows: European carp, $244,322; buffalo, $111,707; catfishes and bullheads, $68,535; sheepshead or drum, $17,729; crappie, $14,419; sunfish, $12,067; black bass, $10,842; suckers and red-horse, $7,845; paddle-fish, $6,210; white, yellow, and rock bass, $5,601 ; lake and shovel-nosed sturgeon, $3,904; wall-eyed pike, $1,174. About three dozen of our 150 species of Illinois fishes have a mar- ketable value as food, and a dozen more may be classed as edible, although not popular enough or abundant enough within our limits to have any commercial value as Illinois products. A dozen of the more useful species are of really good quality, and half of these are among the best of the fresh-water fishes. In the following list the edible species are distinguished in classes of graduated importance, according to our judgment of the estimation in which these fishes are generally held. A few species are put in a lower class than their quality would call for because of their infrequent occurrence in our fisheries. Although the fisheries of the state are not, it must be admitted, commercially of the first importance, they are of sufficient economic interest to make it the duty of all concerned to preserve them care- fully and to take all practicable measures for their improvement and development. Making due allowance fi ir fishes sold in local markets, distributed by peddlers, eaten by those win > take them, and not rep- resented, consequently, in published statistics of the trade, it may fairly be said that Our Illinois fisheries now yield at the rate of a pound a day, throughout the year, of cheap and desirable food to THE FISHERIES OF ILLINOIS CX1X ►J y: yl _cj o t- .3 T3 Ih 3 a! o 3 O Vi .C yj N a in as cj Ih 4) & CJ 3 to •a at o C 0 s a o Ih 3 o a) &c 0 n 5 5 J C/3 o ffl o> c o cu M u CD 2 0 Ih o -3 ■d cu ■d •d \ 3 w c o o -f-» .5 0 S E .3 o 0 B G C3 'ft 0) o Ph * 0 o 03 CJ ^ o a s J fc J3 C/3 CD u o p. yj i _3 JS w 143 3 9 ■d 03 03 cj yi Ih W tO w yj 3 oj 2 E "u -3 V •c 3 o in yj 0 e •d 3 o B *3 E 3 2 5 o o y) JO o a) Ih 0! CS C ^ p. g ^O 3. i £ OJ S c -d o .t; ° "o o Kj "3 01 O 3 *a> J I h t/3 y) yj cn td ^3 o -*-» 3 3 w t-t O •d •d a> E +-> "a 1> a 0) a) +3 'a •h3 o a! 'S. c o 2 o a Eh o o E 3 0 E •d a) C ft .o *, WO q X C ft ,g !" ^ rn ° "' S « ml) O " «- J? >, o a fc - ■» •- s-, S O - >• c «a is § ,0 < . . 6 6' o o GLOSSARY OF TECHNICAL TERMS CXXV Glossary of Anatomical and other Technical Terms* Abdominal ventral fins. Ventrals which are inserted posteriorly, the pelvic bones having no connection with the shoulder girdle. (See key to families, b, note, p. 1.) Acanthopterygian. Spiny rayed. Said of the numerous families of fishes related to the basses and perches, in which part or all of the rays of at least one dorsal fin and the first ray of the ventral fins are of a spinous (unarticulated) character. (See spine and ray.) Accessory caudal rays. Short, procurrent rays on the upper and lower (rather than posterior) part of the caudal peduncle. Accessory pectoral scale. An enlarged scale at the base of the pectoral fin in certain herring-like fishes. Actinosts. Small bones at the base of the paired fins. Adipose fin. A fleshy fin-like structure behind the dorsal fin, as in salmons and catfishes. This is sometimes more or less continuous with the caudal fin, being separated from it only by a notch. Air-bladder. A sac filled with air or other gases, lying beneath the backbone, and either adherent or not to the walls of the visceral cavity. It may be simple (most teleosts) or divided into compartments by constrictions {Catostomidce and Cyprinidce) or of a cellular structure (some Ganoidei). It is typically con- nected with the oesophagus by a duct, which is closed in many recent forms. Ammocates. A name applied to the larval form of lampreys. Amphicwlian. Concave both before and behind. Said of the vertebra; of fishes generally, with the exception of certain forms. (See opisthoca'lian.) Anadromous. Running up rivers from the sea to spawn, as do shad and some sal- monoids. Anal. Pertaining to the anus, or vent. Anal fin. The fin on the median line behind the vent. (Fig. 1, a.) Anal papilla. A protuberance, usually bilobed, in front of the genital pore and be- hind the vent in darters and sculpins. A ngular. A bony element of the lower jaw. Anlrorse. Directed forward. . 1 nus. The posterior external opening of the alimentary canal; the vent. Arterial bulb. (See conus arteriosus.) Articular. A bony element of the lower jaw. Articulated. Jointed. (See ray.) Auditory ossicles. (See Weberian ossicles.) Barbel. An elongated, feeler-like projection, usually about the mouth, chin, or nose, as in the carp, and in catfishes. Branchial. Of the gills (branchice). Branchioslegals. Bony rays supporting the membranes which close the branchial cavity below. (Fig. 1, br.) *In the preparation of this glossary, that of Jordan's Manual of the Vertebrates (ed. 8) has been of substantial assistance, and, naturally, some of the definitions will be found to be the same. In addition, however, a good many new terms have been inserted, and many old definitions amended, applied to particular cases, extended to more informative dimensions, or simplified by reference to figures. CXXV1 FISHES OF ILLINOIS "/. 0 C , >■ K M ft S ;-. _j <- 0) , c V- [o ■3 > 4J •d 3 S (h ■- .S bo which the ventral tins are attached; pubic bone Peritoneum. The membranous inner lining of the abdominal cavity. Pharyngi al boni Bones representing a rift li gill-arch, behind the gills, opposed to i ii oilier, usually in several upper and one lower pairs, as masticatory struc- tures, for which purpose they are, as a rule, armed with teeth. (Fig. 57, lph. and Fig. 56, uph.) ' totnous Having the air-bladder connected with the oesophagus by an open dui i Pit ctO