o □ I- o _J a s 1-^ o m a a ,^^a! THE MOLLUSCAN FAMILY PLANORBIDAE 7? 17 THE MOLLUSCAN FAMILY PLANORBIDAE By FRANK COLLINS BAKER . Curator, Museum of Natural History, ^m.tyiiu& University of Illinois Collation, Revision, and Additions By HARLEY JONES VAN CLEAVE THE UNIVERSITY OF ILLINOIS PRESS URBANA : 1945 Published by the University of Illinois Press under the auspices of the Graduate School. Copyright, 1945, by the University of Ulinois Press. Permission for rejiroduction in any form mav be obtained from the Publisher. Manufactured in the United States of America PREFACE THE WIDE DISTRIBUTION, large number of species represented, and the economic significance from a medical standpoint, as inter- mcfliate hosts of flukes or trematode worms, constitute the family Planorbidae as one of the most important groups of fresh-water Mollusca. It is the largest and most conspicuous of the families of Basoramatophor- ous pulmonate snails. Unlike the terrestrial pulmonates (Stylommatophora Pulmonata) which have been brought to a high state of precise classification from the anatomical studies of Dr. Henry A. Pilsbry and his co-workers, the Basom- matophora are still in a condition of more or less chaos as regards classi- fication, all of the monographs and many of the local studies being based wholly or partly on characteristics of the shell with little regard for rela- tionships which might be gained by a study of the organization of the animal. The condition of this large group as far as classification is con- cerned is little better than that of the land snails seventy-five years ago. In 1911 the writer published a monograph of the Lymnaeidae of North and Middle America, basing the classification on characteristics of the genitalia and radula. In that work it was suggested that studies on Planorbis, Physa, and other groups might follow the publication of the Lymnaeidae volume if it should meet with the approval of the conchologi- cal public. That it is still in general use after an interval of more than thirty years is evidence that its reception has been, on the whole, of a favorable nature. The present volume on the Planorbidae was begun some twenty-five years ago and has been in active preparation for the past ten years. As the work progressed it became evident that adequate treatment of the subject could not be given in a volume similar to that on the Lymnaeidae and so the work has been divided into two parts, part I on the anatomy and classification of the family, and part II* on descriptions of the species of the family inhabiting North and South America and the West Indies. The study of the internal organization of the family Planorbidae has shown that, as in the case of the land snails, the anatomy gives the only true key to a natural classification. The shell alone cannot be relied upon for this purpose because some of the characteristics are often misleading, affording many cases of parallel development, as the presence of lamellae within the aperture, which feature is found in a number of groups which are unrelated anatomically. There are some shell characteristics, however, which are of value in classification when used in conjunction with ana- tomical features. For the anatomical studies recorded in this volume, eighty species and races of the family have been examined, represented by more than 725 specimens. The anatomy of six additional species has been taken from the literature. The number of species examined has been divided among the four subfamilies as follows: Planorbinae 19; Segmentininae 11; Helisoma- tinae 41 ; Planorbulinae 10. A large majority of the known genera and subgenera are represented and it is confidently believed that additional anatomical study will not greatly alter the classification herein set forth. *See title page of Part II (page 213) for statement regarding change in scope of this part. ix X The Molluscan Family Planorbidae The anatomical drawings in this work have all been made by the author with the aid of the camera lucida, and the outlines and much of the detail of the figures are correct from the standpoint of dimensions. Some of the finer details have been filled in by hand on the camera lucida figure. All dissections were made with a Spencer binocular microscope with mag- nification up to seventy-five diameters. The radulae have all been examined under a Zeiss microscope with magnification up to about 1000 diameters. In order that the features of the different organs might be fully known they have been separated and otherwise dissected to bring out all rela- tionships. In many cases sections have been made through organs or groups of organs the better to show structural conditions. Some of the figures are diagrammatic, but in the majority of the figures the author has endeavored to portray the form of the organs as they appeared to him under the microscope. Only the shells of the type species of the different genera and subgenera are figured in the plates prepared for Part I. In the matter of bibliographic citations it has not been deemed neces- sary to include all references to works in which a genus or other group is listed or described. To have done this would have lengthened the work to a large degree without adding greatly to its value. Only the most im- portant citations, including the first one in which the generic name ap- pears, are included. It will be noted that many groups, which have been ignored or placed in the synonymy by previous authors, have been recog- nized in this work. This is particularly true of Asiatic groups which have been little known anatomically. Every generic or group name has been given careful study to ascertain its true relationship. All groups described in this work are arranged under the heading of a genus or of a subgenus, none as sections. Until a greater number of species have been examined for the internal organization this division appears best. Some of the groups herein considered genera may later be placed as subgenera. It does not at present appear to be of any advantage to recog- nize the terms section or subsection for any of the groupings. The list of species included in each genus or subgenus has no pretension to completeness, only those species being listed which have either been examined anatomically or appear from the form of the shell to be related. As additional material is examined some of the species listed may be shifted to other groups and additional species may be included. January, 1942 ACKNOWLEDGMENTS IN LARGE ^MEASURE the successful preparation of this work has been due to the help and encouragement of many American concholo- gists and zoologists. The authorities of the United States National Museum at Washington, through the interest of Dr. Paul Bartsch, Curator of Recent and Cenozoic Invertebrates, have freely lent the collections of Planorbidae for study. Without this magnificent material, probably the largest assemblage of species of this family extant, it would have been imjiossible to understand the relationships of the American species of the family. ]Mr. William J. Clench, Curator of the Department of Mollusca, ]\Iuseum of Comparative Zoology of Harvard University, supplemented the National Museum material by the loan of thousands of specimens, many of the series of species being incomparable in size and completeness. Both of these gentlemen have also contributed much anatomical material. Other individuals and institutions have lent or given specimens for both anatomi- cal and dry study. To all of these the writer is under the greatest obliga- tion. The list of those rendering assistance is given below: Dr. C. C. Adams, Director, State Museum of New York, Albany Dr. E. A. Andrews, Professor of Zoology (Retired), Johns Hopkins University, Baltimore Dr. H. BuRRiNGTON Baker, Professor of Zoology, University of Pennsylvania, Philadelphia Dr. John C. Bequaert, Professor, Harvard University Medical School, Cambridge Dr. Edward W. Berry, Professor of Paleontology, Johns Hopkins University, Baltimore Dr. S. Stillman Berry, Redlands, California Dr. Stanley T. Brooks, Curator of Lower Livertebrates, Carnegie ]\Liseum, Pittsburgh Dr. A. R. Cahn, formerly Associate Professor of Zoology, University of lUinois, Urbana Dr. E. P. Cheatum, Professor of Zoology, Southern IMethodist Universit}', Dallas Dr. William A. Clemens, formerly of the Pacific Biological Station, Nanaimo, B.C. Now Professor of Zoology, University of British Columbia, Vancouver, B.C. Miss Ruth E. Coats, Tellamoole, Oregon Dr. Ernest C. Faust, School of Tropical ^ledicine, Tulane University, New Orleans Mr. C. J. Firkins, Edwardsville, Illinois Dr. Thural Dale Foster,* University of Illinois, Urbana Mr. Calvin Goodrich, Curator of ]\Ioilusca, University of Michigan Museum, Ann Arbor Dr. G. D. Hanna, Curator of Paleontology, California Academy of Science, San Francisco Professor Junius Henderson,* Curator Emeritus, University Museum, Univer- sity of Colorado, Boulder Dr. L. G. Hertlein, Assistant Curator of Paleontology, California Academy of Science, San Francisco Mr. Shintoro Hirase,* Zoological Institute, Tok3-o, Japan Dr. William A. Hoffman,* School of Troi)ical Medicine, San Juan, Puerto Rico Mr. Leslie Hubricht, St. Louis Botanical Gardens, St. Louis, Missouri Mr. A. Jankowski, Warsaw, Poland Mr. A. LaRocque, Canadian Geological Survey, Ottawa, Canada Mr. John B. Litsey, Dallas, Texas *Deceased. xi xii The Molluscan Family Planorbidae Mr. Paul McGinty, Boynton, Florida Dr. Roy W. Miner, Curator, Department of Living Invertebrates, American Museum of Natural History, New York City Mr. William B. Marshall, formerly Assistant Curator of Mollusca (Retired), U.S.N.M., Washington, D.C. Dr. Paul R. Needham, Associate in Aquatic Biolog}^, U.S. Bureau of Fisheries Mr. Olof 0. Nylander, Caribou, Maine Dr. Henry A. Pilsbry, Curator of Mollusca, Academy of Natural Sciences, Philadelphia Dr. C. Ping, Fan Memorial Institute, Peiping, China Dr. Baini Prashad, Zoological Survey of India, Indian Museum, Calcutta, India Dr. H. S. Rao, Zoological Survey of India, Indian Museum, Calcutta, India Dr. D. S. Rawson, Professor of Zoology, University of Saskatchewan, Canada Dr. Harold A. Rehder, Assistant Curator, Division of Mollusca, U.S.N.M., Washington, D.C. Dr. Horace G. Richards, Academy of Natural Sciences, Philadelphia Mrs. Imogene C. Robertson, Buffalo Museum of Science, Buffalo Dr. Hugo G. Rodeck, Curator, University of Colorado Museum, Boulder Mr. W. F. Shay, Department of Science, Normandy High School, St. Louis Miss Elberta C. Smith, University of Colorado Museum, Boulder Mr. H. W. Smith, Atlantic Coast Biological Station, St. Andrews, New Brunswick Dr. Harley J. Van Cleave, Professor of Zoology, University of Illinois, Urbana Dr. Henry Van der Schalie, University of ^Michigan Museum, Ann Arbor Mr. T. VAN Hyning, Curator, State Museum, Gainsville, Florida Dr. Bryant Walker,* Detroit Dr. Alexander Wetmore, Assistant Secretary, Smithsonian Institution, in charge of U.S.N.M., Washington, D.C. Mr. Berlin H. Wright,* Penn Yan, N.Y., and Lakeland, Florida The writer is highly appreciative of the help given him by the Uni- versity of Illinois Library, not only for the volumes consulted in its stacks, but also for its aid in securing through the interlibrary loan system many rare volumes not in our own library. To jNIiss Fanny Dunlap the author is deeply indebted for this help. The libraries lending these books include the John Crerar Library, Chicago; Columbia University of New York; Johns Hopkins University, Baltimore; Harvard University, Cambridge; University of Michigan, Ann Arbor; Iowa State College, Iowa City; The U.S. Geological Survey, Washington, D.C; and the Congressional Library of AVashington, D.C. The photographs of the shells and the copies from author's works were all made in the Photographic Laboratory of the University of Illinois, under the direction of Mr. Ray R. Hamm, Manager of the Laboratory. The author desires to express his deep appreciation of the help given by Dean R. D. Carmichael, of the Graduate School of the University of Illinois, who has greatly aided in the preparation of the work by providing several grants of funds for the making of the photographic plates. Without this assistance this volume could not have been completed. f Frank Collins Baker *Deceased. tThe University of Illinois Press here records its appreciation of the assistance of Professor Harley J. Van Cleave, who, in addition to writing the 'Memorial' and compiling the bibliography attached thereto, has carefully checked the copy and the plates, including the legends, and has given many helpful suggestions on the typo- graphical and scientific arrangement of the data. Mrs. Katharine Hill Paul, artist in the Department of Zoology, has rendered valued service in making numerous altera- tions of the original drawings to ensure satisfactory engravings. — H.E.C. CONTENTS Preface ix Acknowledgments xi A Memorial to Frank Collins Baker (1867-1942) .... xvii A Chronological List of the Scientific Publications OF Frank Collins Baker xxv Original Articles and Books xxv Biographical Contributions xxxv Book Notices and Reviews xxxv PART I Classification and General ^Morphology I. General ^Morphology 3 A. External Appearance of the Animal 3 B. General Internal Anatomy 4 (a) The Reproductive System 4 (b) The Digestive System 9 (1) The Jaw 10 (2) The Radiila 11 (c) The Renal System 12 (d) The Circulatory System 13 (e) The Respiratory System 14 (f) The Nervous System 14 (g) The [Muscular System 15 C. The Shell 15 II. General Ecology 17 General Environmental Conditions 17 Variations in Different Environments 18 Locomotion 19 Food 19 Food for Other Animals 19 Length of Life 20 The Planorbidae as Hosts for Parasitic Worms 21 III. XlDIFICATION AND EmBRYOLOGICAL DEVELOPMENT .... 25 A. Development of Helisoma scolare (Jay) 25 B. Nidification and Development in Other Species of Helisoma 28 (a) Self-fertilization or Autofecundation 29 (b) The Development of Helisoma 31 (1) Helisoma trivolvis lentum (Say) 31 (2) Helisoma trivolvis fallax (Haldeman) 32 (3) Helisoma duryi nor male Pilsbry 33 (4) Helisoma duryi eudiscus Pilsbry 34 (5) Helisoma tenue calif orniense F. C. Baker .... 34 (6) Other Records of Egg Laying 35 Xlll 59931 xiv The Molluscan Family Planorhidae IV. Distribution in Time and Space 37 A. Geological History and Distribution 37 B. Geographical Distribution 38 Dispersal of Species 39 V. Historical Sketch of Classifications 41 VI. A New Classification of the Family Planorbidae . 45 General Discussion 45 Anatomical Keys to Groups 46 Systematic List of Genera and Subgenera Recognized in This Work 48 VII. Systematic Account of the Subfamilies, Genera, and Subgenera — Recent and Fossil 50 Subfamily Planorbinae H. A. Pilsbry, 1934 50 Genus Planorbis Geoff roy, 1767 51 Genus Anisus Studer, 1820 (Gray, 1847) 55 Subgenus Anisus SS 57 Subgenus Costorbis Lindholm, 1926 61 Subgenus Bathyomphalus (Ag.) Charp., 1837 .... 62 Genus Odontogyrorbis Lorenthey, 1906 64 Genus Gyraulus (Ag.) Charp., 1837 65 Subgenus Gyraulus SS 66 Subgenus Torquis- Dall, 1905 72 Genus Armiger Hartmann, 1840 75 Genus Taphius H. and A. Adams, 1855 79 Genus Tropicorbis Pilsbry and Brown, 1914 80 Subgenus Tropicorbis SS 85 Subgenus Obstructio Haas, 1939 85 Subgenus Lateorbis F. C. Baker, New Subgenus ... 85 Genus Afroplanorbis Thiele, 1931 86 Genus Syrioplanorbis F. C. Baker, new name for Heterodiscus West 88 Genus Biomphalaria Preston, 1910 89 Genus Australorbis Pilsbry, 1934 90 Genus Anisopsis Sandberger, 1875 94 Subfamily Segmentininae F. C. Baker, New Subfamily ... 96 Genus Segmentina Fleming, 1817 96 Genus Hippeutis (Ag.) Charp., 1837 100 Genus Polypylis Pilsbry, 1906 104 Genus Helicorbis Benson, 1855 106 Genus Trochorbis Benson, 1855 108 Contents xv VII. Systematic Account of the Subfamilies — continued Subfamily Segmentininae F. C. Baker, New Subfamily — continued Genus Pingiella F. C. Baker, New Genus 109 Genus Intha Annanclale, 1922 112 Genus Drepanotrema Fischer and Crosse, 1880 114 Subgenus Drepanotrema SS 118 Subgenus Fossulorbis Pilsbry, 1934 118 Genus Paraplanorbis Hanna, 1922 119 Genus Platytaphius Pilsbry, 1924 120 Genus Acrorbis Odhner, 1937 121 Subfamily Helisomatinae F. C. Baker, 1928 123 Genus Helisoma Swainson, 1840 123 Subgenus Helisoma SS 124 Subgenus Seminolina Pilsbry, 1934 129 Subgenus Pierosoma Dall, 1905 134 Subgenus Planorbella Haldeman, 1842 150 Genus Carinifex ^Y. G. Binney, 1863 154 Genus Vorticifex :Meek, 1870 159 Genus Perrinilla Hannibal, 1912 160 Genus Parapholyx Hanna, 1922 161 Genus Pompholopsis Call, 1888 165 Genus Planorbarius Froriep, 1806 166 Subfamily Planorbulinae Pilsbry, 1934 172 Genus Planorbula Haldeman, 1840 172 Subgenus Planorbula SS 173 Subgenus Haldemanina Dall, 1905 177 Genus Promenetus F. C. Baker, 1935 178 Genus Menetus H. and A. Adams, 1855 182 Subgenus ^lenetus SS 183 Subgenus ]\Iicromenetus F. C. Baker, New Subgenus . 187 Genus Planorbifex Pilsbry, 1934 190 VIII. Groups of Uncertain Affinities 192 Subfamily Choanomphalinae Germain, 1923 192 Genus Choanomphalus Gerstfeldt, 1859 192 Genus Poecilospira Morcli, 1853 194 IX. Family Bulinidae 196 Genus Indoplanorbis Annandale and Prashad, 1920 . . . 196 X. Genera Wrongly Referred to Planorbidae 202 Genus Nautilinus :\Iousson, 1872 202 Genus Palaeorbis Beneden and Coemans, 1867 202 XI. Bibliography 204 xvi The Molluscan Family Planorbidae PART II The Planorbidae Inhabiting North and South America AND THE West Indies XII. Foreword 215 XIII. Descriptions of New Species and New Varieties. . 218 Genus Troyicorhis 218 Tropicorbis shimeki, New Species 218 Genus Helisoma 219 Helisoma nnceps anticostianum, New Variety 219 Helisoma anceps bartschi, New Variety 219 Helisoma anceps idahoense, New Variety 220 Helisoma anceps politum, New Variety 221 Helisofna binneyi randolphi, New Variety 221 Helisoma caribaeum cubense, New Variety 222 Helisoma columbiense, New Species 222 Helisoma kennicotti, New Species 223 Helisoma pilsbryi preblei, New Variety 224 Helisoma subcrenatum perdisjunctum, New Variety . . . 224 Helisoma trivolvis marshalli, New Variety 225 Helisoma campanulatum dalli, New Variety 226 Helisoma campanulatum pleistocenicum, New Variety . . 226 Helisoma campanulatum rideauense, New Variety . . . 227 Genus Parapholyx 227 Parapholyx effusa dalli, New Variety 227 Parapholyx klamathensis sinitsini, New Variety .... 228 Parapholyx pusilla, New Species 229 Genus Planorbida 229 Planorbula smithii, New Species 229 Genus Menetus 230 Menetus color adoensis, New Species 230 Menetus cooperi crassilabris, New Variety 230 Menetus cooperi planospirus, New Variety 231 Menetus dalli, New Species 231 Menetus dilatatus floridensis. New Variety 232 Menetus labiatus, New Species 232 Menetus portlandensis, New Species 233 Illustrations of the Anatomy and of Shells 235 Index to Text 521 Index to Illustrations 527 A MEMORIAL TO FRANK COLLINS BAKER (1867 to 1942) FRANK COLLINS BAKER became Curator of the Museum of Natural History in the University of IlUnois on January 1, 1918. From that date onward until his death on May 7, 1942, his chief interests centered around his work and his associations on the L'rbana campus. Though he carried on extensive field studies during these years, they were chiefly summer vacation employment, and Urbana remained the focal point of his attention and activity. His appointment as Curator of the L'niversity ]^Iuseum gave him the opportunity to cooperate in the development of a museum de- voted primarily to teaching. To this work he brought a broad back- ground of professional experience in every aspect of museum work and at the same time drew freely from his research experiences to create on the L'rbana campus a series of collections and exhibits the prime purpose of which was ever that of aiding in student instruc- tion. As in all good teaching one of the first requisites is that of enlisting responsive interest by attractive presentation of fact or material, so likewise in his displays interest was always sought though it was never purchased by cheapening spectacular showman- ship. In his synoptic display of the animal series, the dry framework of classification became clothed by artistic and balanced organization of his materials. Groups represented only by fossil remains were treated as integrated with modern expressions of life, not as isolated representations of a dead past. For one whose career never placed him before classes for deliver- ing formal instruction, he gave evidence of keen appreciation of the museum as a supplement to laboratory and classroom teaching, and at all times offered hearty cooperation to the teaching faculty in creating habitat groups and other exhibits embodying both specific detail and broad principle. Under his curatorship the Museum of Natural History became utilized by diverse student groups. Biology, geology, and geography students found the displays meaningful; students in agriculture came to study the well-organized habitat groups of pests of farm crops, and art students frequented the exhi- bition halls for sketching. ^Ir. Baker's concept of the functions of a museum combined not alone the aspects of display and instruction but a third objective as well, namely, that of research. Throughout his curatorship. he la- bored to establish and organize research collections. Naturally, the fields of his own interests were most emphasized and these included such diverse interests as the ]\Iollusca. archeology, and paleontology. xvii xviii The Molluscan Family Planorbidae In certain specialized areas of these three fields, the University col- lections have assumed a significance greater than might be expected in a small museum. The collections of Mollusca are especially rich in representatives of the fresh-water and land Mollusca, the direct result of Mr. Baker's active research program. Extensive field col- lecting was particularly stimulated by his association with the Natural History Survey of Wisconsin in the preparation of his ex- haustive two-volume work on the Mollusca of Wisconsin (1928). His long association and collaboration with the Illinois State Natural History Survey gave him access to extensive collections, especially in late years when he was engaged in an intensive field study of the land snails of Illinois which culminated in the Fieldbook of Illinois Land Snails published (1939) by the State Natural History Survey. A revival of interest in researches on the archeology of the State by the University resulted in amassing within the Natural History Museum huge quantities of pottery and artifacts for the care of which Mr. Baker became responsible. His early interest in the Pleistocene fauna was revived and. stimulated by a cooperative program of studies inaugurated by the State Geological Survey. Enormous series of Pleistocene material in quantitative samples were studied by Mr. Baker, whose services in cooperation with the State Geological Survey were recognized by his appointment to the position of Consultant in Pleistocene Paleon- tology on its staff (1919). The Pleistocene collections under this joint arrangement between Museum and Survey assumed great im- portance and wide reputation as repository of critical materials, and numerous collectors throughout the country sent samples for critical determination. Thus, at the time of Mr. Baker's death, the Pleisto- cene collections, which are now deposited in the State Geological Sur- vey, had become one of the significant study collections in this field. Mr. Baker's interest in research was deep and genuine, and the esteem with which his results are held gives evidence of the effective- ness of his activities in scholarly pursuits. His earliest studies on Mollusca were, in keeping with that period, restricted largely to the study of the shells but he early became an advocate of the study of the soft parts of the living animal which produces the shell and the volume which this sketch accompanies is the culmination of his pro- gram of anatomical studies. New apparatus and improved optical equipment made him often express the regret that he could not go back and do again all the earlier studies which he carried on with less adequate laboratory equipment. Early in his career as a student of Mollusca, Mr. Baker by his own collecting and by personal exchange, began amassing a private collection of fresh-water Mollusca. This collection centered around his chief interest, the fresh-water pulmonate snails. The operation of the old adage. To him who hath shall be given,' here finds exempli- fication, for students of Mollusca regularly sent doubtful specimens Memorial and Bibliography xix to him for classification or verification, and samples of those sub- mitted were added to his cabinet. At the time of his death, the two families Lymnaeidae and Planorbidae were particularly well repre- sented in the Baker Collection, which, as indicated elsewhere in this volume, was presented to the United States National Museum. A member of many scientific societies, he cherished particularly the election as Corresponding Alember of the Zoological Society of London. He was a fellow of the Geological Society of America and likewise of the Paleontological Society of America. At the time of his death he was president of the American Malacological Union. Other societies in which he held membership include: American Association of Museums, Museum Association of Great Britain, Ecological Society of America, American Limnological Society, Ot- tawa Field Naturalist's Club, and Sigma Xi. He was a fellow of the American Association for the Advancement of Science and held life membership in the Chicago Academy of Sciences and in the Illinois State Academy of Science. With the years, his zeal for research never waned. In fact, gradu- ally increasing deafness which tended to shut him off from an earlier appreciation of music and from easy communication with his friends gave him opportunity for uninterrupted study in which he could become so completely immersed as to ignore surrounding distrac- tions entirely and to forget adversities, even when he faced some of life's greatest tragedies. These statements regarding Mr. Baker, as a man and a scientist, would not be complete without some narration of his early years and background. Frank Collins Baker, son of Francis Edwin and Anna Collins Baker, was born in Warren, Rhode Island, on December 14, 1867. His family later moved to Providence, and there the boy received his early education and for a time attended a business college. Still struggling between the alternatives of business and science as a career, he was for a time employed by the Gorham Silversmiths, and there he learned the techniques of exactness and accuracy which he later maintained were of value in his scientific work. He attended Brown University for one year (1888-89). Even be- fore this time he had developed a consuming interest in shells which he often remarked were the favorite childhood toys brought to him from distant oceans by a seafaring grandfather. He left Brown to ac- cept the Jessup Scholarship (1889-91) in the Philadelphia Academy of Sciences and there, at the fountainhead of molluscan studies, the die was cast for his scientific career. In later years he often referred to the inspiration which he obtained from mere proximity to Joseph Leidy and other notables in the library and in the programs of the Academy. There likewise he became associated with H. A. Pilsbry, and the tradition for sound molluscan studies, which has always been an important aspect of the Academy program, gripped him. XX The Molluscan Family Planorhidae In 1890, Air. Baker, as zoologist, was a member of an exploring party from the Philadelphia Academy into Mexico. The travels in Cuba, Yucatan, and ^Mexico afforded by this expedition had on him the same broadening influence which travel has brought to all the great naturalists and inspired him to consider natural faunal areas instead of political units in subsequent programs of comprehensive taxonomic studies. Thus his monograph on the Lymnaeidae (1911) was not confined to the boundaries of the United States but encom- passed a more natural zoogeographical scope of 'North and ^Middle America.' and the program on the Planorbidae, results of which are embodied in this volume, was extended to include even broader scope in order to secure comprehensive treatment of a taxonomic unit without reference to political subdivisions. After his return from Mexico, Mr. Baker published his first separate book (1895), a small popular work entitled 'A Naturalist in Mexico,' which wove to- gether a narrative of the trip, a description of the country, and scientific observations. An intimate correspondence with Henry A. Ward of Rochester, part of which has been available to the present writer, ended in an arrangement wherein Mr. Baker was to become associated (1891) as Invertebrate Zoologist with the influential Ward's Natural Science Establishment. Few strictly educational institutions in the early history of this country have wielded the influence exerted by this private concern in the training of natural scientists, especially those headed toward museum work as a profession. While residing in Rochester, he became a frequent visitor in the home of John Hall. On June 12, 1892, he married Lillian Alay Hall who was his con- stant companion until her death in 1934. While his employment by the Ward Establishment was primarily for the identification and organization of the Ward collections of Mollusca, Mr. Baker at the same time selected and organized an extensive synoptic display of museum specimens representing all the groups of the invertebrates, which was being prepared for exhibition at the Chicago World's Columbian Exposition in 1893. Upan com- pletion of this task, Mr. Baker accompanied the exhibit to Chicago where he supervised its installation. At the close of the Exposition, the Ward exhibit was purchased by Marshall Field as part of the nucleus for the beginning of the Field Columbian Museum, and Mr. Baker was engaged as curator in the newly established museum (1894). But that same year he was chosen curator of the old, long established Chicago Academy of Science, w^here he succeeded and had association with men of the calibre of Robert Kennicott, William Stimpson, and T. C. Chamberlin. It was here that he perfected the techniques of museum display and administration and for the first time had opportunity to develop an intensive program of research, integrated with his professional work. Unfortunately, after about two decades with the Academy, a change in administration placed Memorial and Bibliography xxi the Academy in the hands of an individual who acrimoniously op- posed the place of research as a museum function. Even this adverse atmosphere brought no reduction in the research program which Mr. Baker had embarked upon, for nights and holidays were free from dictatorial domination. Some measure of his accomplishment during the Chicago period is available in the larger monographs which punctuated the continuous stream of smaller contributions from his desk. Three of his outstanding volumes were published during the twenty-one years of Mr. Baker's association with the Chicago Acad- emy. These are: two volumes on the Mollusca of the Chicago Area (1898 and 1902) and the monograph on the Lymnaeidae (1911). Another undertaking of particular importance — The Life of the Pleistocene — was virtually completed during the years with the Chi- cago Academy. However, publication of this volume was not afforded until after Air. Baker came to the University of Illinois (1920), and it was then published by the University Press. The work on this volume marked a new epoch in his research program. Stimulated by an intimate and cordial relation with Professor T. C. Chamberlin of the University of Chicago, Mr. Baker's personal interest in re- search swung toward the study of faunas of the past and interpreta- tion and reconstruction of environmental conditions under which they existed. The material which served as the original basis for this study was made available in unusual quantity by construction of the Chicago Drainage Canal. Apparently endless material was exposed by the dredging operations, but much of this opportunity for research would have been lost had it not been for ]\Ir. Baker's close personal attention to the dredging as it proceeded. Exposure which he experi- enced at that time led to infections which affected his hearing. Conditions there established became progressively worse until in later life his hearing was very seriously impaired. While with the Chicago Academy, ]\Ir. Baker developed a service feature w^hich has become an important aspect of most public mu- seums today and links them closely with the educational program. He began the construction of small portable displays of habitat groups for loan to public schools, thus taking the educational influ- ence of the museum into the schools rather than depending wholly on the unilateral relation of expecting the schools to send their pupils to the museum. The interest in children, and in education, developed by these contacts always remained with him. In the museums under Mr. Baker's direction, the urchin was as welcome a visitor and was as thoughtfully treated as the scholar. Thus, though he never held formal appointment as instructor in any educational institution, he exerted marked influence, and a number of present-day scientists trace the awaking of their interest to his kindly encouragement and enthusiastic attitude toward the field of science. Graduate students in the University of Illinois always found him inspiring and helpful when they approached him with their problems. xxii The Molluscan Family Planorbidae Mr. Baker found deep satisfaction in following the careers of men who attributed part of their early zeal for science to boyhood con- tacts with him and to inspiration growing out of his enthusiasm and kindly interest in their personal problems. One instance of an influ- ence of which he was personally unaware stands out prominently. A mother called at his office in Urbana to present him with a copy of a scientific book written by her son. She explained that the son, who had died while on archeological explorations in a foreign land, defi- nitely attributed his aspiration in the field of science to the benevo- lent and gracious attention of Air. Baker to the queries of an un- known and apparently unpromising urchin frequenting the museum of the Chicago Academy. Mr, Baker resigned from his position with the Chicago Academy in 1915. In that same year, he embarked on a new phase of his career in which his time was given over entirely to field study and research. The newly established New York State College of Forestry, on the campus of Syracus University, employed him as an investigator. For two years he carried on a comprehensive evaluation of the relations of bottom fauna to fish life in Oneida Lake. This program culmi- nated in two volumes of distinctive contributions which were pub- lished by the New York State College of Forestry. Ever since the founding of the University of Illinois, the Museum of Natural History had been in charge of members of the faculty whose foremost obligation had been that of teaching or administra- tion. Under wise guidance of men such as S. A. Forbes and Frank Smith, the Museum had prospered and was able to secure the serv- ices of very unusual collectors and competent preparators w^ho added materially to its development. Toward the end of President James's administration, a renewed interest in archeology and in natural resources together with rapid increase in University enroll- ment led to consideration of the problem of securing a full-time curator for the Museum of Natural History. The position was offered to Mr. Baker w^ho, at the height of his professional career, entered upon his duties in January, 1918. In 1936 Air. Baker reached the age established by the University for retirement from active service but his good health and vigor and the best interests of the University combined to bring about postponement of his retirement for three additional years. In 1939, in his seventy-second year, his colleagues helped him celebrate entrance upon status as Curator Emeritus, which permitted him to devote his entire time to completion of researches in progress. Let- ters of congratulation and appreciation from colleagues and from fellow scientists throughout the country were assembled, bound, and presented to him at a dinner in his honor. The esteem with which he was held as an individual and acknowdedgments of personal debts of gratitude were as sincely expressed as was the evaluation of his scientific work. Memorial and Bibliography xxiii Soon thereafter, illness impaired his opportunity for continuous work in the laboratory, but even under this physical handicap he continued to devote all the time that his strength would allow to the final studies for and preparation of the manuscript for his nuu/nuifi opus — the monograph on The Molluscan Family Plan- orbidae. Volume 1. based on exhaustive anatomical researches, was ready for the editor and work was progressing on Volume II when he was taken critically ill and hospitalization for surgery was unavoid- able. Following the operation he never regained his health but became rapidly weaker and died on May 7, 1942. Slight in stature, unpretentious in attitude, mild in disposition, and kindly, charitable, and unbiased in all of his personal and pro- fessional relations, Mr. Baker has left an undying impression of honesty, integrity, and genuineness in the memories of his many friends and associates. For more than half a century (1889-1942) Mr. Baker continued to publish the results of his researches and observations. Aside from purely incidental notes and compilations, which he continued to pub- lish throughout his career, his early publications dealt largely with distributional studies and problems of taxonomy of the MoUusca. Relatively early he began to shift his interest in Mollusca from purely conchological to malacological lines (about 1897) when he began to study the radulae and anatomy of the soft parts of the molluscs. The interest in Pleistocene paleontology first found expres- sion in a paper published in 1898 and continued through the rest of his life with two posthumous papers on this subject. Faunal studies with considerable attention to ecological relations of the molluscs began early and found particular expression in his monograph on the Lymnaeidae (1911) and in his ecological studies on the fauna of Oneida Lake. These studies stand as background to the interest which found final expression in his contributions as asso- ciate editor of Xaturalist's Guide to the Americas (1926). His long identification with the program of molluscan studies, kindly personal qualifications, and familiarity with the history of the subject led to his being commissioned to prepare biographical sketches for five of the distinguished students of Mollusca in the Dictionary of American Biography (Gould, 1929; Kennicott, 1930; Stimpson. 1932; Tryon, 1933; and Sterki, 1933). Interest in museum administration found expression in a series of papers issued during his years with the Chicago Academy and was revived when he became established in the museum at the University of Illinois. His publications in archeology were stimulated by his responsi- bility for the University collections and were concerned largely with analysis of shells and other remains of animal life encountered in excavations of Indian village sites in the Middle West. In this aspect xxiv The Molluscan Family Planorbidae of his work, he collaborated with various specialists but had closest relations with the late W. K. Moorehead whose reports on studies conducted for the University of Illinois were edited by Mr. Baker. To supplement this analysis it should be recorded that in the period from 1900 to 1915. Mr. Baker edited the Bulletins and other publications of the Chicago Academy of Sciences. From 1913 to 1915 he was assistant editor of Home and School Reference Work, pub- lished in Chicago in seven volumes, to which he personally con- tributed 125 articles on birds. Earlier (1900) he prepared a one-page article on Mollusca for the United Editors Encyclopedia published in New York. In 1926, in addition to serving as associate editor of Naturalist's Guide to the Americas, he prepared the references therein to molluscan distribution. From 1921 to 1926, Mr. Baker wrote numerous reviews of current works on Mollusca for Ecology. In his total contributions, exceeding 350 original articles, more than 250 deal entirely or largely with his chosen field of research, the Mollusca. While many of these are but short, minor notes, some quantitative evaluation of Air. Baker's productivity may be reflected in the fact that more than a dozen of these works enumerated are of such size as to merit classification as separate books. Throughout his active career Mr. Baker kept a carefully compiled record of his publications, a copy of which was in his desk at the time of his death. This list, which he prepared, is here published in full with but few slight editorial changes and corrections. Harley Jones Van Cleave A CHRONOLOGICAL LIST OF THE SCIENTIFIC PUBLICATIONS OF FRANK COLLINS BAKER ORIGINAL ARTICLES AND BOOKS 1889 1. Conchology department in 'The Old Curiosity Shop' (of which department the writer was editor). Cahfornia. 2. Notes on Florida shells. Nautilus, 3:53-54. 3. Description of a new species of Ocinebra. Op. cit., 3:80-81. 4. A few notes oi;i ornithological collecting. Oologists Exchange, New York, 2(9). 5. Notes on the food of birds. Proc. Acad. Nat. Sci. Philadelphia, 1889:266-270. 6. Remarks upon the round-tailed muskrat, Neofibcr allcni True. Op. cit., 1889: 271-273. 1890 7. On the Indian River, Florida. Oologists Exchange, 3(11). 8. Directions for collecting alcoholic specimens of the Mollusca. Old Curiosity Shop, 9(3). . ^ 9. Remarks on Urosnlpinx perrugatus Conrad. Nautilus, 4:29-30. Also m Proc. Acad. Nat. Sci. Philadelphia, 1890:46-47. 10. On the modification of the apex of Murex. Proc. Acad. Nat. Sci. Philadelphia, 1890:66-72. 11. A catalogue of conchological abbreviations. Nautilus, 4:89-91, 115-117. 1891 12. Notes on a collection of shells from southern Mexico. Proc. Acad. Nat. Sci. Philadelphia, 1891:45-55. 13. Descriptions of new species of Muricidae, with remarks on the apices of certain forms. Proc. Rochester Acad. Sci., 1:129-137. 14. Remarks on the Muricidae with descriptions of new species of shells. Proc. Acad. Nat. Sci. Philadelphia, 1891:56-61. 15. Catalogue and synonymy of the recent species of the family Muricidae. Proc. Rochester Acad. Sci., 1:153-172. 16. The caves of Yucatan. Op. cit., 2:2. 17. Notes on a collection of shells from the Mauritius; with a consideration of the Genus Magilus of Montfort. Op. cit., 2:19-40. 18. Catalogue of specimens of Echinodermata, corals, gorgonians, and sponges. Ward's Natural Science Establishment, Rochester, N.Y., iv -f- 82 pages. 1894 19. Further notes on embryonic whorls of the Muricidae. Proc. Acad. Nat. Sci. Philadelphia, 1894:223-224. 1895 20. A glance at the Chicago Academy of Sciences. Nautilus, 8:109-111. 21. The geographic distribution of ttie Mollusca. Science (n.s.), 2:179-183. 22. Preliminary outline of a new classificatioii of the Muricidae. Bull. Chicago Acad. Sci., 2:169-189. 23. Syllabvis of biological lectures. (Delivered before the North Side Science Section of the Chicago Institute of Education). Chicago. 24. A naturalist in Mexico: being a visit to Cuba, northern Yucatan, and Mexico. Chicago, 1895 : viii + 145 pages. 25. Thirty-eighth annual report of the Chicago Academy of Sciences. For the year 1895. 16 pages. 1896 26. On the correct position of the aperture in Plajiorbis. Jour. Cincinnati Soc. Nat. Hist., 19(1) :45-48. 27. Notes on the mental development and intelligence in animals. The Observer, 1896:680-682. XXV xxvi The Molluscmi Family Planorhidae 1897 28. Thirty-ninth annual report of the Chicago Academy of Sciences. For the year 1896. 26 page-s. 29. On the pulsations of the molluscan heart. Jour. Cincinnati See. Nat. Hist., 19(2) : 73-78. 30. Note on Natrix grahami B. and G. (With F. M. Woodruff). Science (n.s.), 5:447. 31. On the effect of music on caged animals. Amer. Nat., 1897:460-463. 32. Critical notes on the Muricidae. Trans. Acad. Sci. St. Louis, 7:371-391. 33. On the modification of the apex in gastropod mollusks. Ann. New York Acad. Sci., 9:685-704. 34. On a collection of mollusks from Grand Tower, Illinois. Nautilus, ll(3):28-30. 35. Further notes on animal intelligence. The Obseryer, 8:193-194. 36. Collecting about Chicago. Sports Afield, 19(2) :112-113. 37. Reason among animals. Op. cit., 19:276-278. 38. Notes on Radulae. Jour. Cincinnati Soc. Nat. Hist., 19(3) :81-93. 1898 39. Do cats remember? Sports Afield, 20:215. 40. The molluscan fauna of western New York. Trans. Acad. Sci. St. Louis, 8(5) : 71-94. 41. Collecting in Florida. Sports Afield, 20:314-316. 42. Notes on mollusks from Acadia, Missouri. Nautilus, 11:36. 43. Fortieth annual report of the Chicago Academy of Sciences. For the year 1897. 27 pages. 44. The Mollusca of the Chicago area.- Part L The Pelecypoda. Chicago Acad. Sci., Nat. Hist. Suryey Bull., 3(1):1-130. 45. A day on the Chicago drainage canal. Nautilus, 12(6) :63-65. 46. A new Sphaerium. Op. cit., 12:65-66. 1899 47. Collecting fresh-water shells. Popular Sci., 33(5) :99-100. 48. Notes on the mollusks of Lilycash Creek. Nautilus, 13(3) :30-31. 49. Study of fresh-water mussels. Popular Sci., 33:194-197. 50. Notes on the Mollusca of Owasco Lake, New York. Nautilus, 13:57-59. 1900 51. Notes on a collection of Pleistocene shells from Milwaukee, Wisconsin. Jour. Cincinnati Soc. Nat. Hist., 19:175-177. 52. On a collection of fresh-water .shells from Rhode Island. Nautilus, 13:112-113. 53. A new museum tablet. Amer. Nat., 34:283-284. 54. The rock shells. Birds and Nature. 7:191-192. 55. The gross anatomy of Limnnca cmarginata Say, yariety Mighehi Binney. Bull. Chicago Acad. Sci., 2(3) : 191-211. 56. A reyision of the Physae of northeastern Illinois. Nautilus, 14(2) :16-24. 57. The teeth of snails. Popular Sci., 34:187-188. 58. Shell collecting near Rochester, New York. Nautilus, 14:69-71. 59. Mollusks in grass. Op. cit., 14:93. 1901 60. The oyster and its relatiyes. Birds and Nature, 9:26-31. 61. A reyision of the Limnaeas of northern Illinois. Trans. Acad. Sci. St. Louis, 9(1): 1-24. 62. Snails of the forest and field. Birds and Nature, 9:74-79. 63. Snails of pond, riyer, and brook. Op. cit., 9:128-133. 64. Snails of the ocean. Op. cit., 9:176-181. 65. The Nautilus and other cephalopods. Op. cit., 9:222-227. 66. New yarieties of fresh-water shells. Nautilus, 15(2):17-18. 67. The digitations of the mantle in Physa. Bull. Chicago Acad. Sci., 2(4) :225-228. 68. Description of a new species of Limnaea. Op. cit., 2(4) :229-230. 69. The molluscan fauna of the Genessee Riyer. Amer. Nat., 35:659-664. 70. The prong-horned antelope. Birds and Nature, 8:179-181. 71. Limnaea auricularia in America. Nautilus, 15(5) :59. 72. The educational yalue of natural history museums. Reyiew of Education, Chi- cago, 7:155-157. 73. Some interesting molluscan monstrosities. Trans. Acad. Sci. St. Louis, 11:143-146. Chronological List of Publications xxvii 1902 74. Fhnwrbis bicariitatiis striaius, n. var. Nautilus, 15(10) :120. 75. Editorial on museum articles. Review of Education, Chicago, 7:361. 76. The Mollusca of the Chicago area. Part II. Gastropoda. Chicago Acad. Sci., Nat. Hist. Survey Bull.. 3(2) :131-410. 77. Starfishes. Birds and Nature, 12:35-37. 78. The cowries and shell money. Op. cii., 12:86-90. 79. Some snails of the ocean. Op. cit., 12:134-139. 80. The descriptive arrangement of museum collections. Museum Jour., (England), 2:106-110. 1903 81. Shell collecting on the Mississippi. Nautilus, 16:102-105. 82. Corals, sea-fans, and sea-whips. Birds and Nature, 13:83-85. 83. The stonv corals. Op. cit., 13:131-133. 84. Coral reefs. Op. cit., 13:179-181. 85. The hydroid corals. Op. cit., 13:225-227. 86. Shells of land and water. A familiar introduction to the study of the mollusks. A. W. Mumford and Co., Chicago, xvi + 175 pages. 87. Pleistocene mollusks of White Pond, New Jersey. Nautilus, 17:38-39. 88. A partial list of the marine mollusks of San Salvador. Bahamas. Op. cit., 17:57. 89. Rib variation in Cardium. Amer. Nat., 37(439) :481-488. 90. Sea urchins and sand dollars. Birds and Nature, 14:179-181. 91. Notes on Murex marcoensis Sowerby. Nautilus, 17-88. 1904 92. The mollusks of Cedar Lake, Indiana. Op. cit., 17:112-113. 93. Some American grasshoppers. Birds and Nature, 15:131-133. (Nom de plume, Collins Thurber) 94. New varieties of American Limnaeas. Nautilus, 18:10-12. 95. The molluscan fauna of the Dells of Wisconsin. Trans. Acad. Sci. St. Louis, 14(2):99-105. 96. Note on PUutorbis tnmcatus Miles. Op. cit., 14(2) :107-110. 97. The arrangement of the collections of Mollusca in the Chicago Academy of Sciences. Museums Journal (England), 2 : 354-360. 98. Spire variation in Pyramidula alternnta. Amer. Nat., 38(453) :661-668. 99. New American Lynmaeas, II. Nautilus, 18:62-63. 100. The bluebird. Birds and Nature, 16:158-161. (Nom de plume, Collins Thurber) 101. The bald eagle. Op. cit., 16:232-236. (Nom de plume, Collins Thurber) 1905 102. The belted kingfisher. Op. cit.. 17:50-51. (Nom de plume, Collins Thurber) 103. The flicker. Op. cit., 17:131-132. (Nom de plume, Collms Thurber) 104. Critical notes on the smaller Lynmaeas. Nautilus. 18:125-127. 105. The long-billed marsh wren. Birds and Nature, 17:179-180. (Nom de plume, Collins Thurber) 106. New species of Lymrmea. Nautilus, 18:141-142. 107. The marsh hawk. Birds and Nature, 17:201-202. (Nom de plume, Collins Thurber) 108. The molluscan fauna of McGregor, Iowa. Trans. Acad. Sci. St. Louis, 15(3) : 249-258. 109. Notes on a collection of shells from Bass Lake, Indiana. Nautilus, 19:27-28. 110. The museum and the public school. Museums Journal (England), 5:50-55. 111. A new species of Lymnaea from Ohio, with notes on Lymnaea parva Lea. Nautilus, 19:51-53. 112. The loggerhead shrike. Birds and Nature, 18:23-24. (Nom de plume, Collins Thurber) 113. The hermit thrush. Op. cit., 18:50-51. (Nom de plume. Collins Thurber) 114. Notes on the genitalia of Lymnaea. Amer. Nat., 39:665-679. 115. The yellow-bellied sapsucker. Birds and Nature, 18:119-121. (Nom de plume, Collins Thurber) 116. The cerulian warbler. Op. cit., 18:167-168. (Nom de plume, Collins Thurber) 117. The American flamingo. Op. cit., 18:213-214. (Nora de plume, Collins Thurber) xxviii TJie Molluscan Family Plauorbidae 1906 118. The bob-white or quail. Op. cit., 19:23-24. (Nom de plume, Collins Thurber) 119. The least bittern. Op. cit., 19:71-72. (Nom de plume, Collins Thurber) 120. The blue-gray gnatcatcher. Op. cit., 19:110-111. (Xom de plume, Collins Thurber) 121. A new variety of Planorbis nautileu.s Linn. Nautilus, 19:120. 122. Lijmnaea hinklcyi n. sp. Op. cit., 19:142-143. 123. Application of De Vries's mutation theory to the molluscs. Amer. Nat., 40: 327-334. 124. Notes on a collection of mollusks from the \-icinitv of Alpena, Michigan. Trans. Acad. Sci. St. Louis, 16(2):1-15. 125. A new Sphaerium from Illinois. Nautilus, 20(2) :21. 126. The dickcissel. Birds and Nature, 19:146-147. (Nom de plume, Collins Thurber) 127. The great blue heron. Op. cit., 19:213-214. (Nom de plume, Collins Thurber) 128. Lyninaea daniehi n. sp. Nautilus, 20:55. 129. A catalogue of the Mollusca of Illinois. Bull. Illinois State Lab. Nat. Hist., 7(6): 53-136. 1907 130. Descriptions of new species of Lyninaea. Nautilus, 20:125-127. 131. The camera in science. Photo Era, 18:185-186. 132. Two new species of Lymnaea. Nautilus, 21:52-55. 133. Some observations on museum administration. Science, 26:666-669. 1908 134. Some instructive methods of bird installation. Proc. Amer. Mus. Assoc, 1:52-57. 135. The Chicago Academy of Sciences. Science, 27:423-424. 136. The Chicago Academy of Sciences: its past history and present collections. Chicago Acad. Sci., special publ., 2:1-7. 137. Note on Lymnaea desidiosa Say. Nautilus, 22:20-23. 138. Suggestions for a natural classification of the familv Lvmnaeidae. Science, 27: 942-943. 139. The Chicago Academy of Sciences. Op. cit., 28:138-140. 140. A new American Planorbis. Nautilus, 22:45. 141. A small collection of shells from Texas. Science, 28:534-535. 142. Provincial museums. Op. cit., 28:684-685. 143. The relation of the State Academy of Science to the Natural History Sur\'ey of the Chicago Academy of Sciences. Trans. Illinois State Acad. Sci., 1:68-69. 144. The Natural History Survey of the Chicago Academy of Sciences. Proc. Amer. Assoc. Mus., 2:15-19. 1909 145. Annual report of the Chicago Academy of Sciences. For the j'^ear 1908. Bull. Chicago Acad. Sci., 3:1-21. 146. A new species of Lymnaea. Nautilus, 22:140-141. 147. Description of a new fossil Lymnaea. Op. cit., 23:19-21. 148. Note on Planorbis binneyi Tryon. Op. cit., 23:41-42. 149. The Chicago Academy of Sciences: Its past history and present collections. Museums Jour. (England), 8:423-428. 150. Range of Lymnaea umbiJicata. Nautilus, 23:80 151. Rei)ort on the educational work of some east American museums. Bull. Chicago Acad. Sci., 3:26-34. 152. Mollusks from Kansas and Oklahoma. Nautilus. 23:91-94. 153. Suggestions for an educational exhibit of mollusks. Proc. Amer. Assoc. Mus., 3:56-59. 154. Exhibition cases without shelves. Op. cit., 3:128-130. 1910 155. A new variety of Lymnaea stagnalis. Nautilus, 23:112-113; 125-126. 156. Note on free public museums. Science, 31:221. 157. Annual report of the curator. Bull. Chicago Acad. Sci., 3:26-45. 158. Annual report of the librarian. Op. cit., 3:45-46. 159. The ecology of the Skokie Marsh area, with special reference to the Mollusca. Bull. Illinois State Lab. Nat. Hist., 8:437-499. 160. Preliminary note on the life of Glacial Lake Chicago. Science, 31:715-717. Chronological List of Publications XXIX 161. Suggestions for an cducutiomil exhibit of niollusks. Muscvniis Jour. (England), 9:394-397. 162. The ecology of the Skokie Marsh area with sjiecial reference to the moUusks. Trans. Illinois State Acad. Sci., 3:106-108. 163. Description of a new Lymnaea. Nautilus, 24:58-60. 164. Mollusks of Unionville, Connecticut. Op. cit., 24:68-69. 1911 165. The Lymnaeidae of North and Middle America, recent and fossil. Chicago Acad. Sci., Special Publ., 3:xyi + 539. 166. Annual report of the curator. Bull. Chicago Acad. Sci., 3:137-150. 167. Annual report of the librarian. Op. cit., 3:151-152. 168. A method of exhibiting large descriptiye labels on the outside of museum cases. Proc. Amer. Assoc. Mus., 4:21-23. 169. School loan collections as prepared by the Chicago Academy of Sciences. Op. cit., 4:36-40. 170. Mollusks of Wellesley Island and yicinity, St. Lawrence Riyer. Nautilus, 25:66-67. 171. The molluscan fauna of Tomahawk Lake, Wisconsin. Trans. Wisconsin Acad. Sci., Arts, and Lett., 17(1) :200-246. 1912 172. A new Flauorbis from Michigan. Nautilus, 25:118-120. 173. Post-glacial life of Wilmette Bay, Glacial Lake Chicago. Trans. Illinois State Acad. Sci., 5:108-116. 174. A method of exhibiting insect collections. Proc. Amer. Assoc. Mus., 6:108-111. 175. Recent additions to the catalog of Illinois Mollusca. Trans. Illinois State Acad. Sci., 5:143-145. 1913 176. A new Lymnaea from Montana. Nautilus, 26:115-116. 177. Pseudogalba, new name for Si))ipsonia. Op. cit.. 26:120. 178. Interglacial records in New York. Science, 36:523-524. 179. Notes on post-glacial Mollu.sca. I. Emmet County, Michigan. Nautilus, 27:7-8. 180. Galba jerruginea in Oregon. Op. cit., 27:24. 181. Mollusca of Wyoming County, New York. Op. cit., 27:54. 182. Notes on post-glacial Mollusca. II. Waukesha County, Wisconsin. Op. c;/., 27:68. 183. Interglacial mollusks from South Dakota. Science, 38:858-859. 1914 184. Northern Idaho shells. Nautilus, 27:104-106. 185. Mollusks from Magician Lake, Cass and Van Buren Counties, Michigan. Op. cit., 28:8-10. 186. L"se of enlarged photographs in museum groups. Proc. Amer. Assoc. Mus 89-91. 187. An eyening with the aquarium and snailery. Nature Study Rey., 10:315-320 1915 188. On the classification of the Lymnaeidae. Nautilus, 29:20-24. 189. Campeloma leunsii Walker in Illinois. Op. cit., 29:36. 190. Mollusks from Berrien County, Michigan. Op. cit., 29:47. 191. Pleistocene mollusks from Illinois. Op. cit., 29:87-88. 1916 192. A mollusk injurious to garden yegetables. Science, 43:136. 193. The fresh-water Mollusca of Oneida Lake, New York. Nautilus, 30:5-9. 194. North American faunal areas. Science, 44:273-275. 195. The relation of mollusks to fish in (Dneida Lake. New York State Coll. For., Technical Publ., 4:1-366. 196. The auroral display of August 26. Science, 44:568. 197. A new yariety of Lamp.dli.s from Oneida Lake with notes on the luteola group. Nautilus, 30:74-77. 198. Further notes on the po.st-glacial biota of Glacial Lake Chicago. Trans. Illinois State Acad. Sci., 7:74-78. 199. The relation of the Mollu.sks of Oneida Lake to the basin of lower South Bay. (Abstract). Ecol. Soc. Amer., 1916. XXX The Molluscan Family Planorbidae 1917 200. Notes on Acella haldemani (Desh.) Binney. Nautilus, 20:135-138. 1918 201. Further notes on the Mollusca of Oneida Lake, New York; the molhisks of lower South Bay. Op. cit., 31:81-93. 202. A moHuscan garden pest. Science, 47:391-392. 203. The animal world in a handful of algae. The Guide to Nature, 10:376-380. 204. Notes on nidification in Gillia and Amnicola. Nautilus, 32:19-23. 205. Description of a new variety of fresh-water mussel from Oneida Lake, New York. Appendix to New York State Coll. For.. Technical Publ., 9:247-248. 206. The productivity of invertebrate fish food on the bottom of the Oneida Lake, with special reference to mollusks. Op. cit., 9:1-264. 207. Post-glacial Mollusca from the marls of Central Illinois. Jour. Geol., 26(7) : 659-671. 208. The relation of shellfish to fish in Oneida Lake, New York. New York State Coll. For., Circular, 21:1-34. 1919 209. Description of a new species and variety of Planorbis from post-glacial deposits. Nautilus, 32(3) : 94-97. 210. Mollusks infested with parasitic worms. Op. cit., 32(3) :97-98. 211. The ecology of North American Lymnaeidae. Science, 49:519-521. 212. A new species of Physa from New. York State. Nautilus, 33:11-13. 213. Studies in aquiculture or fresh-water farming. Nat. Hist., 19:478-488. 214. Molluska of the Crocker-Land Expedition to northwest Greenland and Grinnell Land. Bull. Amer. Mus. Nat. Hist., 41(11) :479-517. 215. Fresh-water Mollusca from Colorado and Alberta. Op. cit., 41(13) :527-539. 216. The Museum of Natural Historv of the University of Illinois. Trans. Illinois State Acad. Sci., 12:57-63. 1920 217. Animal life and sewage in the Genessee River, New York. Amer. Nat., 54:152-161. 218. A new Planorbi.^ from Illinois. Nautilus, 33:123-125. 219. A new form of Amnicola from the Ohio Pleistocene deposits, with notes on a Physa from the same formation. Op. cit., 33:125-127. 220. Physa smithiana, new name for Phy.sa smithii. Op. cit., 33:142. 221. The life of the Pleistocene or glacial period, as recorded in the deposits laid down by the great ice sheets. Univ. Illinois Bull., 17(41) : iv -f- 476 pages. Urbana, Illinois. 222. Pleistocene Mollusca from Indiana and Ohio. Jour. Geol., 28(5) :439-457. 223. Animal life in loess deposits near Alton, Illinois, with descriptions of two new varieties of land shells from the same deposits. Nautilus, 34:61-66. 224. Notes on a small collection of shells from Alaska. Op. cit., 34:67-68. 225. The Museum of Natural History. In 'Sixteen Years at the University of Illinois,' a statistical study of the administration of President Edmund J. James. Uni- versity of Illinois, Urbana, pages 119-121. 226. A mussel survey of the ujijier waters of the \'ermilion River with special refer- ence to the Salt Fork. (With Frank Smith). Trans. Illinois State Acad. Sci., 12:129-131. 227. Effect of sewage and other pollution on animal life of rivers and streams. Op. cit., 13:271-279. 1921 228. The value of ecology in the interpretation of fossil faunas. School Sci. and Math., 21:323-327. 229. Baker's 'Life of the Pleistocene' (reply to criticism by Dr. Shufeldt). The Auk, 38:155-156. 230. Preparing collections of the Mollusca for exhibition and study. Trans. Amer. Micros. Soc, 40(l):31-46. 231. New forms of Pleistocene mollusks from Illinois. Nautilus, 35:22-24. 232. The importance of ecologv in the interpretation of fossil faunas. Ecology, 2: 277-280. Chronological List of Publications xxxi 1922 233. Pleistocene Molluska from northwestern and central Illinois. Jour. GeoL, 30(1): 43-62. 234. Fluke infections and the destruction of the invertebrate host. Jour. Parasitol., 8:145-147. 235. New species and varieties of Mollusca from Lake Winnebago, Wisconsin, with new records for this state. Nautilus, 35:130-133; 36:19-21. 236. New Lymnaeas from Wisconsin and Minnesota, with notes on shells from the latter state. Op. cit., 36:22-25. 237. The molluscan faima of the Big Vermilion River, Illinois, with special reference to its modification as the result of pollution by sewage and manufacturing wastes. Illinois Biol. Monogr., 7(2):1-127. 238. The museum, the original exponent of visual education. School Sci. and Math., 22:651-655. 1923 239. The Pleistocene Mollusca from the vicinity of Joliet, Illinois. Trans. Illinois State Acad. Sci., 15:408-420. 240. A new Anodontoidcs from Wisconsin. Nautilus, 36:123-125. 241. Description of a new Lymiiaea from Yellowstone Park. Op. cit., 36:125-126. 242. The educational value of a university natural history museum. Science, 58: 55-57. 243. Some problems of a university curator. Museum Work, 5:92-94. 244. The use of molluscan shells bv the Cahokia mound builders. Trans. Illinois State Acad. Sci., 16:328-334. 245. A new Physa from California. Nautilus, 38:15. 246. Report of curator, the Museum of Natural History. In 'President's Report,' University of Illinois, 1922-1923:159-162. 1924 247. The place of the museum in university instruction. Museum Work, 7:81-87. (Re- printed in School Life, 10:33-35). 248. The fauna of the Lake Winnebago region. A quantitative and qualitative survey with special reference to the Mollusca. Trans. Wisconsin Acad. Sci., Arts, and Lett., 21:109-146. 1925 249. Report of curator. Museum of Natural Historv. In 'President's Report,' Uni- versity of Illinois, 1924-1925:117-119. 1926 250. Museums and nature. Naturalist's Guide to the Americas, 27-29. 251. The effects of pollution on animal life. Op. cit., 38-41. 252. Nomenclatorial notes on American fresh-water Mollusca. Trans. Wisconsin Acad. Sci., Arts, and Lett., 22:192-205. 253. Bowmanville low water stage of Glacial Lake Chicago. Science, 64:249. 254. Fresh-water Mollusca from White Lake, Oakland County, Michigan. Nautilus, 40:49-52. 255. New forms of Planorbis and Lymnaca with notes on other forms. Op. cit., 41: 23-24. 256. Report of curator. Museum of Natural Historv. In 'President's Report,' Uni- versity of Illinois, 1925-1926:145-149. 1927 257. Description of a new species of Lymnaea from British Columbia. Nautilus, 41 : 23-24. 258. Description of a new species of Somatogyrus from Wisconsin. (With H. A. Pilsbry). Op. cit., 41:24-26. 259. The naiad fauna of the Rock River Svstem; a studv of the law of stream dis- tribution. Trans. Ilhnois State Acad. Sci., 19:103-112. 260. New varieties of Stagnicola from Wisconsin and Wyoming. Nautilus, 40(3) : 85-87. 261. New varieties of Helisoma antrosa from Wisconsin and Minnesota. Op. cit., 40: 82-85. xxxii The Molluscan Family Planorbidae 262. On the division of the Sphaeriidae into two subfamilies; and the description of a new species and genus of Unionidae, with descriptions of new varieties. Amer. Midi. Nat., 10(7) :220-223. 263. Descriptions of new forms of Pleistocene land mollusks from Illinois, with remarks on other species. Nautilus, 40:114-120. 264. Molluscan associations of White Lake, Michigan ; a study of a small inland lake from an ecological and systematic viewpoint. Ecology, 8(3) : 353-370. 265. A new variety of Helisoma campanulata from Michigan. Nautilus, 41:49-51. 266. Report of curator, Museum of Natural Historv. In 'President's Report,' Uni- versity of Illinois, 1926-1927:129-132. 1928 267. Descriptions of new varieties of land and fresh-water mollusks from Pleistocene deposits in Illinois. Nautilus, 41:132-137. 268. The American Bythinia not whollv an introduced species. Trans. Illinois State Acad, of Sci., 20:56-63. 269. Molluscan life of the loess deposits of Illinois. Op. cit., 20:269-292. 270. Influence of a changed en\-ironment in the formation of new species and varieties. Ecology, 9:271-283. 271. The fresh-water Mollusca of Wisconsin. Part I. Gastropoda. Wisconsin Acad. Sci., Arts, and Lett., 1928 :i-xx -f 507 pages. 272. The fresh-water Mollusca of Wisconsin. Part II. Pelecypoda. Bull. Univ. Wis- consin, 1527: vi + 495 pages. 273. The Mollusca of Chautauqua Lake, New York, with descriptions of a new variety of Ptychohranchus and of Helkoma. Nautilus, 42:48-60. 274. Report of curator. Museum of Natural History. In 'President's Report,' Uni- versity of Illinois, 1927-1928:124-127. 1929 275. Fossaria perplexa F. C. Baker and Junius Henderson. Nautilus, 42:103-104. 276. Certain anatomical features of the fresh-water mollusc, Helisoma corpulenta Say. Trans. Amer. Micros. Soc, 48(1) :44-47. 277. Vermont shells. Nautilus, 41:108. 278. Mollusca from Vermilion and Pelican Lakes, Minnesota, with the description of a new variety of Helisoma corpulenta. Op. cit., 42:95-97; 131-136. 279. A study of the Pleistocene Mollusca collected in 1927 from deposits in Fulton County, Illinois. Trans. Illinois State Acad. Sci., 21 :288-312. 280. The use of molluscan shells by the Cahokia mound builders. The Cahokia Mounds, Bull. Univ. Illinois, 26(4) : 147-154. 281. Stagnicola couleensis F. C. Baker. In Henderson, 'Some Fresh-water Mollusca from Washington and Oregon,' Nautilus, 41:118-120. 282. The European starling in Illinois. Science, 69:521-522. 283. Report of curator. Museum of Natural History. In 'President's Report,' Univer- sity of Illinois, 1928-1929:140-146. 1930 284. A new record of Castoroicles ohioensis from Illinois. Science, 71:389. 285. On genus and species making. Op. cit., 72:37-39. 285a. University museum exhibition cases. Museum News, 7(19):11-12. 286. The use of animal life bv the mound-building Indians of Illinois. Trans. Illinois State Acad. Sci., 22:41-64. 287. The molluscan fauna of the southern part of Lake Michigan and its relationship to old Glacial Lake Chicago. Op. cit., 22:186-194. 288. A review of our present knowledge concerning the character and distribution of the Pleistocene aquatic molluscan life of Illinois. Op. cit., 22:411-434. 289. Influence of the glacial period in changing the character of the molluscan fauna of North America. Ecology, 11(3) :469-480. 290. The variation of molluscan life during the Pleistocene and recent time. Nautilus, 44(l):21-24. 291. Notes on Professor Shimek's paper on land snails as indicators of Ecological conditions. Ecology, 11(4) : 788-789. 292. Report of curator. Museum of Natural History. In 'President's Report,' Univer- sity of Illinois, 1929-1930:164-169. Chronological List of Publications xxxiii 1931 293. Description of a new variety of Valvata Icwidi Cm-rier. Nautilus, 44(4) :119-121. 294. Additional notes on animal life associated with the mound builders of Illinois. Trans. Illinois Acad. Sci., 33:231-235. 295. A re-studv of the interglacial moUuscan fauna of Toronto, Canada. Op. cit., 33: 358-366. 296. Ecological relationship of the genus Pomatiop.iin with special reference to Pomon tioits/s Inpidaria. Ecology, 12(3) :389-396. 297. The classification of the large planorboid snails of Europe and America. Proc. Zool. Soc. London, 1931 (2):575-592. 298. Fresh-water Mollusca from central Ontario. (With A. R. Cahn). Ann. Rept., 1929, Natl. Mus. Canada, pp. 41-64. 299. Pulmonate Mollusca peculiar to the Pleistocene period, particularly the loess deposits. Jour. Paleontol., 5(3) :270-292. 300. Plei.stocene historv of the terrestrial Mollusca of Fulton Countv, Illinois. Trans. Illinois State Acad. Sci., 24(2) : 149-155. 1932 301. Stognicola apicina and Stagnicola walkeriann. Nautilus, 45:139-140. 302. Molluscan shells from Etowah Mounds. Chapter V, in W. K. Moorehead's 'Ex- ploration of the Etowah Site in Georgia.' Department of Archeology, Phillips Academy, Andover, Massachusetts, pp. 145-149. 303. The ecology of Say's Limnaeus elodes. Ecology, 13:286-289. 304. New species and varieties of Helisoma and Gyraulus from Canada. Nautilus, 46(1) :6-9. 305. A new race of Pohjgyra apprcssa from Illinois. Op. cit., 46(2) :48-49. 1933 306. Pohjgijru dorfcuilliann and Bulhuoides dcalbatus in Illinois. Op. cit., 47:4-7. 307. A new Stagnicola from Montana. (With Junius Henderson). Op. cit., 47:30-32. 308. Self fertilization and nidification in Physa halei. Op. cit., 47:35. 309. Studies on the bottom fauna of fresh-water lakes. Science, 78:190-191. 310. The genitalia of the Indian mollusk, Indoplanorbis exustus. Jour. Morphol., 55(1):1-13. 311. A new form of Polygyra tridentnta from Illinois. Nautilus, 47(2) :59. 312. New species of Lvmnaeidae from British America. Jour. Washington Acad. Sci., 23(11) :520-523." 1934 313. Description of a new species of Gyraulus. Canadian Field-Nat., 48-27. 314. The variation and distribution, recent and fossil, of the snail Polygyra profunda, in Illinois. Amer. Midi. Nat., 15(2) : 178-186. 315. The variation and distribution, recent and fossil, of the snail Polygyra profunda, in Illinois. (Abstract). Trans. Illinois State Acad. Sci., 25:189. 316. New Canadian Lymnaeas. Canadian Field-Nat., 48:69-70. 317. Two new races and a new species of Helisoma from California. Nautilus, 47: 140-142. 318. The molluscan fauna of the great river valleys of Illinois. Trans. Illinois State Acad. Sci., 26:129. 319. New Lymnaeidae from the United States and Canada: 1. California, Oregon, and other western states. Nautilus, 48(l):17-20. 320. A new mammoth record for Illinois. Science (n.s.), 80:118. 321. A new species of Gyraulus from Canada. Canadian Field-Nat., 48:135. 1935 322. Mollusca from Turkey Run State Park. Indiana. Nautilus. 48(3) : 105-106. 323. Land and fresh-water molluscs from North Star Lake and vicinitv, Itasca County, Minnesota. Amer. Midi. Nat., 16(3) :257-272. 324. Stratiographic sequence of mollu.scan fo.ssils in loess deposits. (Abstract). Proc. ^ Geol. Soc. Amer. for 1934:372-373. 325. New species and races of Lvmnaeidae from Newfoundland. (With Stanlev T. Brooks). Nautilus. 49:10-13. 326. The generic po.sition of Planorbi.<> iimhilicatellu^ with the description of a new group of Planorbidae. Op. cit., 49(2) :46-48. 327. Stagnicola elrodiana, new name for Limnaea montana Elrod. Op. cit., 49:60. xxxiv The Molluscan Family Plauorbidae 1936 328. The generic position of Plonorbis obstructus Morelet. Op. cit., 49(3) ".104. 329. Quantitative examination of molluscan fossils in two sections of Pleistocene loess in Illinois. Jour. Paleontol.. 10(l):72-76. 330. The fresh-water mollusc Hclisuma corpulentum and its relatives in Canada. Natl. Mus. Canada Bull., 79:1-37. 331. Paleontology. In A. L. Lugn's 'The Pleistocene Geology of Nebraska.' Nebraska Geol. Surv. Bull., 10:1-223. (Identifications and comments on pages 122, 123, 183-187, 190, 194, 195, 210-212). 332. New Lvmnaeidae from the United States and Canada, II. Michigan, Minnesota, and Montana. Nautilus, 49(4) : 127-140. 333. The relationship of Parapholyx. Op. Cit., 50:30-31. 334. Remains of animal life from the Kingston kitchen midden site near Peoria, Illi- nois. Trans. Illinois State Acad. Sci., 29:243-246. 1937 335. Identification of shells. In Cole and Deuel, 'Rediscovering Illinois.' Appendix VI, 'Explorations in and around Fulton County,' pages 269-270. 336. Mollu.sca from the Prince Albert National Park, Saskatchewan. Nautilus, 50(4) : 113-117. 337. An Illinois record for the little brown crane. The Auk. 54:388. 338. A new Pleistocene race of Polygyra apprcssa. Nautilus, 51(l):22-23. 339. Pleistocene land and fresh-water Mollusca as indicators of time and ecological conditions. In 'Symposium on Early Man,' held at Academy of Natural Sci- ences, Philadelphia, March, 1937. J.B. Lippincott, 1937:67-74. 340. Abundance of the European starling in Illinois. Science, 85:564. 1938 341. New land and fresh-water Mollusca from the Ui^per Pliocene of Kansas and a new species of Gyraulus from Early Pleistocene strata. Nautilus, 51(4) : 126-131. 342. The Mollusca of the shell heaps or escargotieres of northern Africa. Part III of 'Prehistoric habitation sites in the Sahara and North Africa.' Logan Mus. Bull., 5:185-225. 1939 343. Original copies of Say's 'American conchology.' Nautilus, 52:106. 344. Stagidcola bulimoides vancouverensis nov. var. Op. cit., 52:144. 345. Remains of animal life from the Kingston kitchen midden site near Peoria, Illi- nois. 'The Kingston Site,' by A. M. Simpson. Peoria Acad. Sci., 1939:13-15. 346. Land and fresh-water Mollusca from western Ontario. Canadian Jour. Research, D, 17:87-102. 347. Fieldbook of Illinois land snails. Illinois Nat. Hist. Surv., Manual 2, 166 pages. 1940 348. South American species referred to Planorbula. Nautilus, 53:106. 349. The case of Linmacu.'< sordidus Ku.ster. Op. cit., 53:138-141. 350. A new HcIiso)na from the Pliocene of Florida. Op. cit., 54:17. 351. A new anatomical classification of the Planorbidae. Tenth Ann. Rept. Amer. Malacol. Union, Philadelphia, 1940:4-5. 1941 352. A new species of Drcpanotrema and some preoccupied planorboid names. Nau- tilus, 54:96-97. 353. A new race of Parapholyx effusa. Op. cit., 55:16-17. 354. A study in ethnology of the prehistoric Indians of Illinois. Part II. Contributions to the archaeologv of the Illinois River vallev. Trans. Amer. Philos. Soc. (n.s.), 32(l):51-67. 1942 355. Lymnaea .'itagnalis and Lymnnca (Radix) nuricularia. Nautilus, 55:105-106. 356. Land and fresh-water Mollusca of New Hampshire. Amer. Midi. Nat., 27:74-85. Chronological List of Publications xxxv 357. Collect inji and preserving fresh-water snails. Ann. Rei)t. Amcr. Malacol. Union, Philadelphia, 1941:5-9. 358. A new Gi/raulii.^ from the Pleistocene of California and a new Parapholyx from a supposed Pliocene deposit in Oregon. Nautilus, 55:130-132. 1943 359. Mollusca contained in the test pit deposits. Carnegie Inst, of Washington, Publ. 538:117-119. 1945 360. The Molluscan Family Planorbidae. The University of Illinois Press, Urbana. BIOGRAPHICAL CONTRIBUTIONS (In Dictionary oj American Biography) 1929. Augustus Addison Gould. 1932. George Washington Tryon. 1930. Robert Kennicott. 1933. Victor Sterki. 1932. William Stimpson. BOOK NOTICES AND REVIEWS (In Ecology) 1921 The fresh-water Mollusca of the Parish of Aldenham, by A. E. Boycott. 2:230. Correlation of shape and station in fresh-water mussels, by A. E. Ortmann. 2:231. Natural historv and propagation of fresh-water mussels, by Shira, Coker, Clark, and Howard. 2:314. 1922 The Mollusca collected by the University of Michigan-Walker expedition in southern Vera Cruz, Mexico, by H. B. Baker." 3:342. Final report on the study and appraisal of mussel resources in selected areas of the upper Missi-ssippi River, by N. M. Grier. 3:343. The edible clams, mussels, and scallops of California, bv F. W. Wevmouth. 3:344-345. Mollusca of North Dakota, by Mina L. Winslow. 3:345. Stream pollution. A re^"iew of 'Stream pollution studies,' bv Russel Suter and Em- meline Moore. 3:340-341. 1923 On the effect of salinity on Teredo navalis, bv H. F. Blum. 3:318. The Mollusca of Dickinson County, by H. B. Baker. 4:318. The Champlain Sea, bv Winifred Golding. 4:318. The Mollusca of Oundle, by Rev. C. E. Y. Kendall. 4:319. Variations in the shell of Teredo navalis, by R. C. Miller. 4:319. 1924 The Kentucky River and its mussel resources, by E. Danglade. 4:431. Studies of the biologv of fresh-water mussels. III. Distribution and movements of Winona Lake mussels, by W. R. Allen. 5:220. The Mollusca collected bv the Universitv of Michigan-Williamson expedition in Venezuela, by H. B. Baker. 5:221. Biology and economic value of the sea mussel, Mytilu.'^ rdulii^, by I. A. Field. 5:306. Mollu.^ca of the southwestern states. XI. From the Tucson Range to Ajo, and moun- tain ranges between the San Pedro and Santa Cruz riv(>rs, Arizona, bv H. A. Pils- bry and J. H. Feniss. 5:222. xxxvi The MoUuscan Family Planorhidae The small bottom and shore fauna of the middle and lower Illinois River and its con- necting lakes, Chillicothe to Grafton: Its valuation, its resources of food supply, and its relation to the fishery, by R. E. Richardson. 5:416-418. 1925 Land and fresh-water Mollusca of the Dutch Leeward Islands, by H. B. Baker. 6:193. Conditions imder which Goniobasis livescene occurs in the island region of Lake Erie, by F. H. Krecker. 6:320. 1926 Changes in the small bottom fauna of Peoria Lake, 1920 and 1922, bv R. E. Richard- son. 7:229-230. Illinois River bottom fauna in 1923. by R. E. Richardson. 7:230. THE MOLLUSCAN FAMILY PLANORBIDAE PART I CLASSIFICATION AND GENERAL MORPHOLOGY I. GENERAL MORPHOLOGY A. EXTERNAL APPEARANCE OF THE ANIMAL CONTRARY TO GENERAL CUSTOM, the characteristics of the animal and its gross anatomy will be considered before taking up the shell and its variations. This procedure seems more logical since it is the animal which secretes and builds up the shell or calcareous covering (see plate 70, fig. 1). The head and foot protrude from the shell and bear several important organs. The foot is long and variably narrow, broadly rounded in front, and usually tapering to a point behind. There is a large velar area above and in front of the foot which is retained from the embryonic animal, as in Lyinnaca, and bears the head, eyes, and tentacles. This velum is broad and short and is capable of great extension and retraction; it is usually some- what semicircular in shape. The tentacles are very long and filiform, varying from one-half to the whole length of the foot, and are placed at about the junction of the velum with the foot. The eyes are placed on swellings at the inner base of the tentacles. The mantle collar does not extend beyond the edge of the aper- ture of the shell. The texture of the foot is smooth, not granular as in some of the land snails, and there are no grooves on the body, the animals resembling the Lymnaeas in this respect. The Planorbidae differ from the related family Lymnaeidae in having certain of the organs on the left side (sinistral), the organs in Lymnaeidae being on the right side (dextral). In this respect the Planorbidae resemble the families Physidae and Bulinidae. The tentacles of the Planorbidae, Physidae, and Bulinidae are also similar and differ from the Lymnaeidae and Ancylidae, in which the tentacles are flattened and triangular. The breathing organ of the Planorbidae, a modified lung as in the family Lymnaeidae, is supplemented by a prolongation of the anal region (auri- form lobe), called the pseudobranch or false gill, which may take over the function of breathing when the animal is submerged and can not obtain free air. This organ is highly vascular, many blood vessels entering it from the lower part of the lung cavity. It is comparatively a recent organ, being post-natal in origin, not having been observed in embryological development. The pseudobranch varies greatly in shape, being long and narrow, wide, leaf-like, or rounded in different genera. It always bears a portion of the rectum and the anus opens at the upper right side. There is usually a ridge, more or less heavy and distinct, which begins on the upper part of the rectum and ends in the middle or at the base of the pseudobranch. The variations of the pseudobranch are shown on the plates illustrating the anat- omy of each genus. A siphon-like extension of the mantle, called the pncumostome or respiratory opening, which may be greatly expanded, jirovides a tube-like conduit for free air to reach the lung. The jiseudo- branch is on the left side of the body and the pneumostome is to the right of this organ nearer the median line of the neck. 4 The Molluscan Family Planorbidae The genital outlets are on the left side of the neck, the male opening just behind the left tentacle and the female opening a short distance behind the male opening in the side of the neck. In many individuals the penial complex has been observed protruding from the male opening (plate 29, figs. 6, 7, 11, 12), the animal having been killed while in breeding con- dition. That self-impregnation of the female system by sperm from the extended penial complex is possible is easily believed when the closeness of the two sex outlets is observed. The body above the foot may be flatly rounded or it may be rounded above and flattened on both sides of the foot (plate 70, fig. 10). Good figures of the animal of Tropicorbis are shown on plate 78. The color of the animal differs in the various genera. Mostly it is bluish-slate or blackish, grayish, or brownish, the color being lighter on the base of the foot and on the tentacles. In some species the color is yellow- ish. There are often flecks or spots of white on the foot and tentacles. The mantle, especially over the lung and kidney, is in many groups heavily blotched with black or brown. The shell may be carried perpendicularly, as in Helisoma (plate 70, fig. 7) , or it may lean to the left sicle, causing the shell to be pseuclodextral or ultradextral, as in Gyraulus and JMenetus (plate 70, fig. 9). B. GENERAL INTERNAL ANATOMY The internal anatomy includes the following systems: Reproductive, Di- gestive, Respiratory, Renal, Circulatory, INIuscular, and Nervous. The most important internal structure for classification purposes is the reproductive system and this will be first considered. [a] The Reproductive System Like other Basommatophora, the Planorbidae are hermaphroditic with the organs of the two sexes mostly separated. The difi^erent organs may be tabulated as follows: ' vergic sac verge sperm canal Female organs <{ nidamental gland diaphragm or muscular ring preputium penial gland penial gland duct pilasters ^ muscles f ovotestis ] ovisperm duct or ] hermaphrodite 1^ duct Male Organs. External form. In the natural position the penial complex lies over the vagina and uterus (plate 39, fig. 3). When pulled away from this position its form is seen to be more or less cylindrical and to consist of a large bulbous lower portion, preputium (PR) and a smaller pyriform portion, the vergic sac (VS, plate 24, fig. 11). A narrow tube, the vas deferens (VD) is inserted at the summit of the vergic sac. This descends to Male organs. vagma uterus oviduct nidamental gland spermatheca spermathecal duct , albumen gland ' penial complex vas deferens prostate prostate duct , seminal vesicle Penial complex. Common to both male and female. General Morphology 5 near the male openinti; wlicre it is concealed in the muscular tissue of the neck of the animal and appears again near the female opening (plate 24, fig. 15 1. In some species the vas deferens is enlarged as it enters the vergic sac, the enlargement being similar to the epipliallus of the land snails (plate 39, fig. 7, Mcnetus). In one group of species (the Helisomatinae) there is usually a duct (pcnial gland duct, plate 24, fig. 11, DC) which normally lies coiled at a point between the vergic sac and the preputium (plate 27, fig. 9, DCO). This may be very long, as in HelUoma trivolvu (i:)late 24, fig. 11) or short, as in Hclisoma anceps (plate 23, fig. 3, DC). In another subfamily (Planor- binae) there is no ])enial gland duct except in two or three genera. There are one or two retractor muscles of the penial complex (plate 24, fig. 11, RM; plate 39, fig. 9, RM; plate 34, fig. 2) and a number of muscles believed to be supporting muscles to retain the penial complex in position. The retractor muscles enter the columellar muscle but the supporting muscles are attached to the muscular wall of the forepart of the body. The supporting muscles may in a measure perform the office of additional retractor muscles in some genera, especially in helping to retract the pre- l)utium after eversion. There do not appear to be any protractor muscles; the penial complex becomes turgid by blood pressure. The penial complex assumes many shapes in the genera belonging to the subfamily Helisomatinae. The preputium may be pushed upward and the vergic sac may occupy a position on the side of the prei)utium as in Helisoma campamdatum (plate 27, figs. 5-8). The vas deferens is continued near the female complex and borders the uterus and oviduct where it is a small tube (plate 24, fig. 15, Helisoma trivolvis). Just above the spermatheca the prostate appears. This organ varies greatly in the different genera. In Helisoma (plate 24, fig. 15, PRS) it is somewhat elongated and fan-shaped and the compound diverticula empty directly into the sperm duct along a very small portion of that tube. A cross section of the prostate in Helisoma trivolvis illustrates this condition (plate 24, fig. 13; see also plate 27, figs. 4 and 12, cross sections of Hclisoma ca)npamdatum) . The section is seen to be distinctly fan- shaped. In some other genera the prostate duct is separated from the sperm duct and vas deferens and the prostate is greatly lengthened. The prostate is composed of many or few diverticula arranged in a single series, each diverticulum being attached to and emptying into the separate prostate duct, which in turn empties into the vas deferens below the prostate (plate 14, figs. 7, 9; plate 1, figs. 1, 7). Bevond the prostate the vas deferens is continued as a somewhat larger tube, the sperm duct (plate 27, fig. 14, SPD; plate 24, fig. 15). At its distal end the sperm duct unites with the oviduct to form the ovisperm duct or hermaphrodite duct (plate 27, fig. 14; plate 34, fig. 6). About midway of the ovisperm duct is a glandular enlargement which has been called the seminal vesicle (SV). Many students of both fresh- water and land pulmonates simply call this region an enlargement of the ovisperm duct, but it is distinctly glandular and different from the ovi- sperm duct in structure. It also occupies the position above the prostate, where it lies in other animals. It is recognized as the seminal vesicle by Simroth (1912, p. 501) and by Larambergue (1939, p. 94). Taylor (1900, p. 359) calls the small sac-like organ into which the duct of the albumen 6 The MoUuscan Fcunily Planorhidae gland enters, the seminal vesicle, but as this organ is an adjunct of the male system in all animals it could scarcely be located in an organ of the female system. The swelling near the albumen gland is the carrefour. The seminal vesicle is variable in form in the different species and genera and provides another feature for classification purposes (see plate 35, fig. 5, Carinifex jacksonensis; plate 1, fig. 1. Planorbis planorbis; plate 14, fig. 7, Gyraulus albus). Female Organs. The vagina ( VG) , usually a thick walled, wide tube, passes imperceptibly into the uterus (U) which is usually much enlarged. A large sacculated body, the nidamental gland (NG, sometimes called egg gland) follows the uterus and is usually placed over the uterus and the oviduct. The oviduct (OD) lies back of the gland and is much narrowed as it passes backward to join the ovisperm duct. The method of junc- tion of the oviduct and sperm duct with the ovisperm duct varies in different genera. The albumen gland (AL) is a large, more or less elongated organ, com- posed of many small alveoli. In its natural position it lies over the stomach and a loop of the intestine passes under it causing a channel to be formed on the under side of the albumen gland (plate 38, fig. 9, Menetus opcrcu- laris; plate 15, fig. 1, Gyraulus hirsutus) . The organic relations between the albumen gland and the oviduct are somewhat complicated. A small duct extends from the albumen gland and enters a large bulbous swelling which is attached to the end of the oviduct before that organ combines with the sperm duct to form the ovisperm duct. This gland or bulb is the carrefour which receives the products of the albumen gland and from which they enter the oviduct (see plate 34, fig. 6, Carinifex ponsonbyi; plate 35, figs. 6, 7, Carinifex jacksoriensis) . Taylor (1900, p. 359) erroneously calls the carrefour the seminal vesicle. The spermatheca or receptaculum seminis (S) is a bulbous or pear- shaped organ with a narrow duct of variable length which enters the vagina at its junction with the uterus. Its function is said to be that of receiving the sperm (in the form of a spermatophore) during copulation and to store it safely until the eggs descend from the ovotestis, at which time they are fertilized by the stored sperm. The vagina is usually very short but may be of considerable length in some species. Organs Common to Both Systems. The ovotestis (OT) is embedded in the liver and fills about one whorl of the shell. It varies in form much as does the prostate, the two organs being more or less synchronous in this respect, a valuable feature in classification. In the Helisomatinae it is many-lobed, the diverticula branching fan-wise from the ovisperm duct (plate 27, fig. 4, Helisoma campanulatum ; plate 34, fig. 9, Carinifex pon- sonbyi). In the Planorbinae and Scgmentininae the diverticula are in pairs; the two diverticula are attached directly to the ovisi)erm duct (plate 16, fig. 9, Gyraulus deflectus obliquus) . During the breeding season the diverticula may be filled with both ova and sperm, the ova either ripe for expulsion or developing (plate 10, fig. 2, OT, Drepanotrema hofjmani). The ovisperm duct is a small tube of variable length, enlarged near the middle to form the seminal vesicle. Both ova and sperm are produced in the same diverticulum. They are said to arise simultaneously from indifferent epithelial substance and may General Morpliology 7 be found developing together in a single diverticulum (see Crabb, 1927, p. 75). It is thought by most malacologists that the spermatozoa ripen first, descend during copulation, and are stored in the spermatheca of the female system until the ova ripen and descend through the oviduct, and that fertilization occurs when the ova and sperm meet in the lower part of the uterus or vagina, just before the depositing of the egg capsule. Some cytologists declare that fertilization occurs in the ovotestis diverticulum and that the fertilized egg descends and is deposited without the necessity for copulation. See Clapp 1927 for a discussion of this subject. Typical eupyrene spermatozoa and nucleated o^'lm^: of Gyraulus circumstriatus (TryonI are shown on plate 52, figs. 14-16. The Penial Complex, The male organ, which I have called the penial complex, contains a number of features which are of great value in sys- tematic diagnosis. The whole organ is divisible into two parts, a lower swollen or bulbous portion called the preputium (PR) and an upper portion called the vergic sac (VS). The latter contains the penis proper or verge (V), which may be short and fat (plate 1, fig. 5, Planorbis planorbis) or very long and narrow (plate 10, fig. 6, Drepanotrema hoffmani). All grades of length and diameter between these extremes are to be found in the different genera. The verge may be modified at its extremity by the presence of a dagger- like object called a stylet (plate 16, fig. 6, ST, Gyraulus deflectus obliquus; plate 14, fig. 1 and fig. 6 Gyraulus albus) . In these examples the outlet canal for the passage of the spermatozoa is at the side. In other genera there may be a fleshy papilla or appendage at the end of the verge (PA) with the outlet of the canal in the middle at the base of the papilla (plate 2, figs. 5, 6, Segmcntina nitida) . In still other genera the termination of the verge is simply rounded with the canal outlet in the center (plate 38, fig. 15, Moietus cooperi calioglyptus) . Other slight modifications are found in some genera. Between the vergic sac and the preputium there is an organ which I have called the diaphragm (D). This is a muscular ring which separates the two parts of the penial complex. This may be a simple ring with a central perforation (plate 39, fig. 7, Menetus cooperi) or it may be a dependent papilla (plate 23, fig. 6, Helisoma anceps; plate 24, fig. 10, Helisoma trivolvis; plate 16, fig. 5, Gyraulus deflectus obliquus). The preputium always has several vertical ridges on the inside called pilasters (PL) which may serve to guide the verge or the penial gland during protrusion. In 1926 (Trans. Wis. Acad., V. 22, pp. 200, 201) the writer called atten- tion to a peculiar gland found in the preputium of the genus Helisoma. Subsequent study has shown that this organ is found in several other groups or genera of American, Euroi)ean, and Asiatic jilanorbids. This gland is of variable shape, iiyriform, rounded, or elongated (plate 23, fig. 2, Helisoma anceps; plate 24, figs. 8 and 14, Helisoma trivolvis). In sec- tion it is seen to be cup-shaped, to be lined on the sides with folds and to have many small folds in the bottom of the cup. The gland is attached to the inner wall of the preputium either midway between the male opening and the muscular ring (diaphragm), or somewhat nearer this ring in some species. 8 The Molluscan Family Planorhidae From the base of the cup, and piercing the integument of the pre- putium, is a duct of variable length (DC) , which, if long, is folded on the outside of the preputium (plate 27, fig. 9, Helisoma campanulatum) ; or, if short, simply lies on the surface of the preputium (plate 23, fig. 2, Helisoma anceps) . When coiled on the outside of the preputium it is bound to that organ by short muscles. Sections through the cup are shown on plate 23, fig. 1, plate 24, fig. 1, and plate 27, fig. 1. The duct terminates at the muscular ring or diaphragm (D), pierces the wall of the lower part of the vergic sac, and terminates just above the ring (plate 23, fig. 6, Helisoma anceps; plate 24, fig. 10, Helisoma trivolvis) , or in a groove in the ring (plate 36, fig. 9, Parapholyx effusa) . The function of the penial gland is at present insufficiently known. It was once thought by the writer to be connected with the formation of the spermatophore and was called the spermatophore gland (Baker, 1931, p. 581), but this belief scarcely agrees with the structure of the gland. In section this organ is seen to have two parts, each of which may have a different function. In Helisoma trivolvis (plate 24, fig. 4) the gland shows a large cup-shaped cavity, the walls of which are lined with vertical folds (GF). The bottom of this cup is. lined with folds laid crosswise. The long duct begins at the bottom of the cup and terminates in the vergic space (DC) of the vergic sac (VS) just above the muscular ring or dia- phragm (D). In some species, as Helisoma duryi and its varieties, the duct begins in a small cavity or cup at the end of the gland (plate 33, figs. 3, 10), the walls of which have vertical folds. The larger cup-shaped cavity has no connection with the smaller cavity or its duct. In some species, notably in the genus Menetus, there is no external duct, connection with the vergic space being effected by an open channel (plate 42, figs. 3, 4). Another group of Menetus has a short duct on the inside of the preputium (plate 39, fig. 7). In Menetus and some other groups there is a small channel in the muscular ring (plate 39, fig. 7, D). Helisoma anceps shows this feature well (plate 23, figs. 2, 6). Parapholyx effusa klamathensis (plate 36, figs. 9, 10) also shows the canal in the muscular ring. It appears possible that one of the functions of the penial gland might be to expand the opening in the muscular ring or diaphragm which is normally nearly or quite closed, and prepare it for the protrusion of the verge. The penial gland duct possibly carries a fluid, secreted by the ver- tical folds in the gland cup, to the diaphragm to facilitate the passage of the verge. But there is another function of the gland. It has been observed that during copulation not only is the verge extruded from the male opening, but also the whole penial gland. This has been observed in many species of Helisoma (H. duryi normale, plate 33, fig. 16; H. trivolvis lentuni, plate 29, figs. 7, 11, 12; Promenetus exacuous, plate 41, fig. 9). In all species of Planorbidae the verge is extruded during copulation. In a specimen of Drepanotrema lucidum examined (plate 11, figs. 1, 2, 6, 7) the verge and penial gland protruded together from the male opening. It is probable that the gland portion with the cup-like cavity lined with vertical folds is an excitatory organ or sarcobelum, for in the species possessing this gland there is no special apparatus for this purpose such as occurs in other species General Morphologij 9 which have a horny stylet or fleshy papilla at the end of the verge {Gyraulus, Anisus, and other genera). Another feature observed in connection with the penial gland is that the i)enial complex is often seen in a bilobed condition, the gland being pushed upward in the preputium causing the vergic sac to appear as though attached to the side of the preputium. This condition occurs mostly in HcUsoma (plate 25, figs. 1, 6, 7, 9; plate 24, figs. 1, 2). The evolution of this feature was observed in specimens of Helisoma ccunpanulatum and is shown on phite 27, fig. 7 being the nonual form and figs. 6, 5, and 8 showing the gradual change to the bilobed condition. Much remains to be learned about the function of the penial gland. Observations of the living snail in aquaria should help to solve some of the questions. It may be observed, however, that this is not so easily ac- complished as might be supposed. More than a dozen acjuaria were kept under observation by the writer for several years, and while the animals were seen in apparent coitus on several occasions, the protrusion of the gland was not seen. Perhaps histological studies would help, especially before and after breeding. The subject is worthy of a doctor's thesis. As was recorded in the study of the family Lymnaeidae (Baker, 1911), there is great variation in the form of the genitalia of the genera of the family Planorbidae. As in the Lymnaeidae, also, this modification occurs mostly in the male organs, principally the penial complex, but includes also the ]:)rostate and seminal vesicle. The female organs are uniform in position and shape, only the spermatheca and its duct vary in form and length to any degree. The male organs, therefore, afford useful features upon which to base a natural classification of the family, since the characters of the different groups are constant and uniform. [b] The Digestive System The digestive system of the Planorbidae is similar in many respects to that of the family Lymnaeidae. The system naturally divides into three parts, the first consisting of the buccal sac, the oesophagus, and the salivary glands, the second part the region of the stomach with the liver connec- tions, and the third part the intestine and rectum (see fig. 1, plate 48). The buccal sac is usually pear-shaped, the oesophagus entering it at the upper middle portion. There are retractor and protractor muscles and nerves received from the buccal ganglia. The salivary glands are paired, a duct entering the buccal sac on each side near the oesophageal connection. The salivary glands, usually cylindrical and elongated, are composed of many small lobules. The two glands are joined behind and form a con- tinuous loop or ring. These organs are very uniform in the different species of the family (see plate 70, figs. 12, 13). The oesophagus is usually rather long (about one-fourth as long as the intestine), beginning as a tube of small diameter and enlarging as it approaches the stomach region. The stomach is a large muscular body composed of three parts, first the crop, w'hich is an enlarged portion of the oesophagus, then the gizzard, which is an indistinctly bilobed body of large diameter, and third the pyloris, or opening into the intestine. The gizzard is not as distinctly bilobed as in Lymnaea but is of the same nature. When ojiencd it is found 10 The Molluscau Family Planorhidae to contain small particles of siliceous matter, evidently sand taken in with the food to serve for the breaking up of the ingested food. On the under side of the pyloris, near the duct of the liver, there is a finger-like process or blind sac which appears to be the stylotheca con- taining the crystalline style. This blind sac is present in all species of the family examined. Internally the sac contained a gelatinous substance or was empty. The liver or digestive gland covers the posterior part of the stomach region in its natural position. It has two unequal lobes which form the posterior part of the animal and in which the ovotestis is con- cealed. The liver is composed of a great number of small lobules, more or less digitiform. It is well supplied with blood vessels which form a plexus on and in the organ. A large duct enters the pyloric portion of the stomach at the point of junction with the blind sac. The intestine is very long. It bends around the stomach from the end of the pyloris and passes backward for a distance. It then forms a single loop wdiich bends forward and extends to the fore part of the animal on the left side (the right side in the Lymnaeidae). The rectum, the greatly enlarged portion of the intestine, supports a central ridge or crest on the upi5cr side which extends to and over the pseudobranch. The anal opening is always near this ridge on the pseudobranch, to the right and above this organ. Variation in the digestive system is noted only in the form of the stomach region, short and rotund in some species (plate 48, fig. 1, Helisoma trivolvis) or elongated and narrow in other species (plate 48, fig. 8, Bathyomphalus contortiis) . The loop of the intestine sharply borders the stomach in some species (fig. 1) though in some species it extends forward without a loop (fig. 8). [1] The Jaw The mouth of the Planorbidae is provided with two important organs which afford characteristics for classification, the jaw and the radula. The horny jaw lies in the upper part of the mouth at the fore end of the buccal sac (plate 70, fig. 13). As in Lymnaea, the mouth is somewhat T-shaped in repose. In the upper part of the T lies the superior jaw, which is wide and low, of a brownish color, striated vertically on its front part, the striations producing a saw-like condition on its lower, cutting edge (plate 49, fig. 1, Helisoma anceps) . The lateral jaws, two narrow, brown, horny ribbons, emargin the lips or sides of the mouth. They are connected with the lateral margins of the superior jaw by a narrow projection from the upper part of the lateral jaws. These side jaws form a question-mark figure, as will be noted in the figures on plate 70. The jaws, superior and lateral, are attached to a cartilage which in turn is attached to the roof of the mouth. The jaws are moved by several distinct muscles. The jaws of the Planorbidae fall into two principal types or variations. The most common is the group described above, with large superior jaw and two smaller lateral jaws. Another type is horseshoe-shaped and in this there is but one division which appears to represent the fusion of the lateral and superior jaws of the first type. The striations of the superior jaw of the first group become separate vertical plates in the second group, producing a segmented jaw. This segmentation extends to the lower part General Morphology 11 of the side of the horseshoe, showing that tlie hiteral jaws are inokidcd in the segmentation (see plate 50, fig. 16, Gijraidus parvus). A peculiar jaw, not included in the usual segmented type of the family, is that of Cariuife.T in which the jaw is b()w-shai)ed (or roundly horseshoe- shaped) and is composed of many narrow plates fastened to a heavy cartilage (plate 49, fig. 19, Carinifex ponsonbyi; fig. 18, Carinifex jackson- ensis) . Althcnigh belonging to the subfamily Helisomatinae the jaw is prac- tically of the Planorbinae type. Figure 17 on plate 49 shows the large size of the cartilage in this genus (C. iacksonensis) . This type of segmented jaw is suggestive of the polyplacognath group of land snails. It is said to be a very ancient type of jaw which would seem to indicate that the Planorbinae group of the family is more ancient than the Helisomatinae group (except Carinifex which has the primitive form of jaw). The marginals of the radula also indicate a primitive form of radula. [2] The Radula The radula of the Planorbidae is ribbon-like as in the Lymnaeidae. It lies on a subquadrate cartilage near the rear end of the buccal sac. The front end of the radula extends toward the mouth of the snail and the rear end is bent downward into a radular sac which forms a rounded protrusion or bump at the back of the buccal sac (see plate 70, figs. 12, 13). The radula grows forward from this sac as the functional teeth at the front end of the ribbon become worn by use. There are protractor and retractor muscles which iiull the radula backward and forward, over its cartilage, during the act of cutting u\) food particles. In use, the radula is moved from behind forward, like the tongue of a cat lapping food from a plate, as described by Sterki many years ago. The lingual ribbon of the Planorbidae carries many teeth in transverse rows as in the family Lymnaeidae. There may be as many as 200 rows with 85 teeth in a row or a total of 17,000 teeth in one ribbon. The central tooth is always bicuspid and in some groups (as in Drepanotrema) there are one or more accessory cusps on either side of the central cusps. There is a series of duplicating teeth on each side of the central tooth. This row is divisible, as in the Lymnaeidae, into lateral, intermediate, and marginal teeth. The lateral teeth are usually tricuspid and comprise an inner, short entocone, a large median mesocone, and a smaller outer ectocone (see plate 57, fig. 1). The cusps are usually dagger-like and may be wide or narrow. The intermediates are those teeth between the typical lateral and marginal teeth which show certain modifications, as splitting of the ectocone or entocone into smaller cusps. The marginals are usually somewhat claw-like with a variable number of small cusps. The mesocone usually persists in the earlier marginal teeth and may be recognized by its large size and central position. The law of mesometamorphosis applies to the Planorbidae as well as to the Lymnaeidae. As stated by Pilsbry this law is as follows: All modifications of the teeth proceed from the median line of the radula outwards toward the edges, the outer marginal teeth being the last to be modified (Guide to Study of Helices, p. xiii). The marginals of the Planorbidae are of the same ])rimitive type as are those of the Lymnaeidae, showing a close relationshii) between these two 12 The Molluscan Family Planorhidae families and also their common descent from the tectibranchiate stock of marine mollusks. The lateral teeth of the Planorhidae show a wider degree of variation than do the lateral teeth of the Lymnaeidae, indicating, per- haps, that the Planorhidae may be somewhat younger in development. In studying the teeth of the Planorhidae it must be remembered that only the unworn teeth show the true characteristics of the radula. Also the teeth must be in their natural position on the radula ribbon and not tilted or otherwise disturbed. The Planorhidae are divisible into two groups by the form of the marginal teeth. One group, including the genus Helisoma and other divisions of the subfamily Helisomatinae, have long and narrow reflec- tions reaching far below the base of attachment and with the distal end and the outer margin multiserrate (see plate 57). The other group, includ- ing the genus Planorhis and other divisions of the subfamily Planorbinae as well as some of the subfamily Segmentininae, have short, wide reflec- tions high up on the base of attachment and only a few^ serrations or cusps on the lower margins (see plate 69). The lateral teeth are very uniform in both groups, these being mostly tricuspid, the cusps rounded or sharp and dagger-like. In several groups (as Drepanotrema and Segmentina) the laterals are modified by the addition of several cusps, causing the teeth to be 6 or 7 cuspid. These exceptions appear to be due to a splitting of the three cusps of the normal lateral teeth (entocone, mesocone, ectocone) found in the majority of planorbid genera. As with the other organs, the radulae offer sound criteria for classification purposes. [c] The Renal System The kidney or renal organ (nephridiumt of the family Planorhidae is a large and conspicuous part of the snail's anatomy, occupying a consider- able portion of the body whorl of the animal. It lies to the left of the lung cavity, the genitalia being between the kidney and the ureter (see plate 14, fig. 4, U, NG). Viewed from the ventral side, the kidney consists of two parts, a small upper saccular portion with the pericardium at the right (SK) and an elongated lower portion (TK). A section through the middle of this portion of the kidney (plate 44, fig. 9) shows a central tube or lumen flanked on each side by a large vein, the pulmonary vein on the right side (AP) and the renal vein on the left side (RA). The central tube, the tubular portion of the kidney, is regularly marked by internal septa which project into the lumen for a greater or less distance. The tubular portion is surrounded by thick walls of spongy tissue, the most conspicuous part being a distinct ridge (RK) . To the left of this ridge (in the section) there is another conspicuous ridge on the roof of the mantle. At the lower end of the tubular portion is the short ureter (UR). This is a small tube which turns to the left, usually more or less upward, and discharges into the mantle cavity. The figures on plates 44 to 47 show the various forms of ureter and the relationships of the different parts of the kidney. In 1940, Mattox, working on another group of snails, pointed out the fact that the kidney may reflect specific characters. A series of sections through the kidney of Australorbis glabratus (plate 45, figs. 7 to 11) show the internal form of the kidney at different points in its length. In fig. 1, plate 45, an arrow indicates the place where each General Morplioloyy 13 section is made. Figure 7 (E) is a section through the sacculate part of the kidney below tlie pericardium, and shows the lumen partly filled with folds extending from the walls of the kidney. In fig. 8 (D) the section shows the tubular portion of the kidney with a few folds extending from the walls, also the large pulmonary vein at the right and the smaller renal vein at the left. In figs. 9 and 10 (C, B) the same features are shown. In fig. 11, near the lower part (A), the kidney is flattened and broadened and the veins are smaller. All figures show the variation in the form of the ridge in different portions of the kidney. The blood vessels (veins) lie in close proximity to the tubular jiart of the kidney and pick up the blood to be carried to the heart. The folds iu' the tubular portion of the kidney are metameric in their presence and one section may pass through a portion of the kidney where these are present, or it may pass between two sets of folds, as shown in figs. 16 and 17 on plate 45, as well as on other plates. The ridge on the kidney is mostly confined to members of the subfamily Helisomatinae and offers a valuable criterion for the separation of this planorbid group. The Planorbinae are mostly without this ridge. The ureter of the Planorbidae is described as straight, but no exit of this nature was found in any species examined. All had a short ureter, partly reflexed, as shown in the figures on the plates. [d] The Circulatory System The circulatory system of the Planorbidae is similar to that of the Lym- naeidae and other Basommatophorous Pulmonata. The heart lies to the right of the kidney (instead of to the left as in Lymnaea) and consists of a ventricle and an auricle enclosed in an oval pericardium (plate 44, fig. 2, PC, AU, VT). The aorta (AO) extends backward from the ventricle and divides into two branches or arteries, the visceral artery which supplies the digestive, genital, and other systems in the posterior part of the body, and the cephalic artery which bends around and forward, carrying blood to the organs in the head, foot, etc. These arteries branch frequently, the branches becoming smaller, and terminate in contact with the venous system either by small arterioles or through lacunae or blood sinuses which connect the arterial system with the venous system. The venous system consists of blood vessels which convey the blood back to the heart after circulation through the kidneys, lung, and other parts of the system. A large branchial vein borders the kidney on the right side, carrying blood to the auricle. A large renal vein also borders the left side of the kidney, entering the saccular portion (see plate 44, fig. 2, AP, RA). Venous sinuses are present and store the blood after circulation to be carried to the renal and respiratory systems for purification. In the Planorbidae the blood (haemolymph) contains a substance (haemoglobin) which gives it a pinkish or red color. This is an active substance occurring abundantly in the respiratory system and differs from the bluish blood (liaemocyanin) which occurs in most mollusks. Its pres- ence in Planorbis is said to be associated with the poorly oxygenated hab- itat occui^ied by most species of this group in stagnant pools or lakes and ponds poorly supplied with oxygen. This statement, however, is open to question, since many species of the Planorbidae live in habitats abundantly 14 The Molluscan Family Plauorbidae supplied with oxygen, in company with Lymnaeas and other fresh water piihnonates. The pseudobranch is probably helpful in supplying oxygen to the blood, as it is highly vascular (plate 14, fig. 4, P). [e] The Respiratory System Respiration in the Planorbidae is effected as in the Lymnaeidae and other aquatic pulmonale mollusks. Free air is admitted into a large mantle cavity abundantly lined with blood vessels forming a plexus on the dorsal wall of the mantle cavity. This lung cavity lies on the right side of the mollusk, next to the kidney, and is bordered on the left by the pulmonary vein (plate 44, fig. 2, L). The lung cavity is placed on the right side of the body in sinistral species iPlanorbis, Physa) but on the left side in dextral species (Lymnaea). In the Planorbidae the presence of the secondary brancliium, the pseudobranch, enables the animal to respire without coming to the surface. This organ is of various shapes, but is always an outgrowth of the branchial cavity walls and lies to the left of the pulmonary siphon to which it is attached (plate 14, figs. 3, 4, P). It may be a simple rounded fold or it may be flat with a distinct ridge down its center. It is abundantly supplied with a plexus of blood vessels which absorb oxygen from the water. The rectum passes through the pseudobranch and its outlet (anus, A) is usually above and about at the middle of the pseudobranch. The rectum usually has a large crest or ridge on its upper surface which diminishes in size at the lower part where it extends over and to the edge of the pseudobranch (see plate 25, fig. 3, Helisoma pilsbryi; plate 28, fig. 8, Hclisoma scalare; plate 35, fig. 4, Carinifex jacksonensis) . The breathing orifice or pulmonary siphon (pneumostome) is an out- growth of the mantle which is capable of forming a tubular conduit or siphon through which free air may be admitted to the lung (see the plates mentioned above). The respiratory, renal, and circulatory systems are intimately connected and should be considered together to understand the conditions governing the respiration and blood circulation of the animal. [f] The Nervous System The nervous system of the family Planorbidae differs little from that of the family Lymnaeidae (see Baker, 1911, plates 1 and 5). A nerve ring surrounds the oesophagus posterior to the buccal sac (plate 48, fig. 18). There are two cerebral ganglia above the oesophagus (CG). Below the oesophagus there are two pedal ganglia (PG), two buccal ganglia (BG), two visceral ganglia, and a single abdominal ganglion. Two pleural ganglia are connected with the visceral, pedal, and abdominal ganglia. The left cerebral ganglion sends nerves to the penial complex (plate 48, fig. 17, Helisoma anceps) , which divide to send branches to the vergic sac, penial gland duct region, and retractor muscle, as well as to other parts of this comj^lex. In the Planorbidae these nerves are sent off from the left instead of the right ganglia, because the group is sinistral. In the Lymnaeidae, a dextral group, the nerves arise from the right ganglia (see Baker, 1911, plate 5). General Morphology 15 [g] The Muscular System The muscular system of the family Planorbidae does not differ from that of the family Lymnaeidae except in i)ositions due to the sinistrality of the animal. The most important muscles for classification purposes are those of the male generative system. C. THE SHELL The shells of the Planorbidae are mostly orb-shaped, wheel-shaped, or disc-shaped, rarely becoming a conical spiral as in Lymnaea and Physa. Several physoid types occur, as the Helisoma scalare of Florida. Such types sometimes occur in other species of the family as abnormal or pathologic forms, and have been noted in the genera Helisoma and Carinifex. Scalari- form individuals may also occur in any species and have been noted par- ticularly in the smaller species of the genus GyrauliLS. The shell may be closely coiled, like a watch spring, or loosely coiled, and of few or many whorls. It may be so fiat that one wonders how an animal can find enough room to function in so small a space, as Drepano- trema cultratum, or it may be almost globose, as Helisoma pilsbryi. It may be as thin as paper or thick and very solid. The shells of the larger speLcies^_especially in_ Helisoma, are carried almost perpendicularly as in jHelisojnq trivolvisjnaa^o^tomum (shown on plate 70, fig. 7) , or it may lie'ahiiost flat as in Planorbida^nksi (shown on plate 70, fig. 11). In all species of the family Planorbidae the ^nital organs are on the left side^ -and the animal is sinistral. But the shells are not all strikingly Sinistral. Such large groups as Helisoma, Planorbarius, and Indoplanorbis are obviously sinistral, usually exhibiting a distinct right and left side- wh^ii ia loconiption. But the smaller species are tipped to one^ side, to the left, and are apparently dextral and are usually de- scribed as pseudodextral or ultradextral. In such species the upper side (right) is umbilical and the lower side (left) is apical. These shells, while truly sinistral, appear as dextral. In most works on this family the shells have all been considered dextral and figured as such. Quite a literature has developed in the controversy as to whether the shells of Planorbis are dextral or sinistral (see Baker, 1896. Jour. Cincinnati Soc. Nat. Hist., 19, p. 45). In size the planorbids range from the tiny Armiger crista, less than 2 mm. in diameter, to the large Helisoma trivolvis macrostomum, which attains a diameter of 30 mm. The whorls may be rounded on the periphery or this region may be sharply carinated or squarely flattened. The lower (umbilical) surface may be so flattened that no umbilical opening is indi- cated, or it may be deeply indented forming a distinct umbilicus. Sutures may be deeply indented or scarcely visible. The aperture is most frequently rounded, ovate, or half-moon shaped. It may be armed with lamellae or entirely free from such obstructions. The outer lip may be thin and sharp or it may be strengthened by a heavy ridge or callus. There may be, also, more or less of a callus on the parietal wall. As most species are planorboid in form there arc few modifications of the columella, as are found in the familv Lvmnaeidae. 16 The Molluscan Family Plauorbidae The sculpture of the planorbid shell consists mostly of growth lines which may be very fine and thread-like or coarse and rib-like. In some species there have been developed costae or ribs more or less evenly dis- tributed. In a few species the epidermis forms paper-like crests or frills, as in Helisoma anceps royalense. Spiral impressed lines are found in most of the species of the family. These are usually rather heavy and conspicuous but in some species they are very fine. In a few species the spiral lines are very faint or absent, as in Menetus opercularis. Malleated individuals are comparatively rare in the Planorbidae although they are common in the Lymnaeidae. The epidermis or periostracum of the planorbids is usually rather thick and heavy. In some groups the shell appears devoid of an epidermis, the surface being shining and waxy. The remarks on sculpture in the Lymnaeidae Monograph (pp. 3, 4) apply equally well to the Planorbidae. The color of the shells of the family Planorbidae is usually some variety of horn color, light or dark. In some groups, as Australorbis, the color is rich brown or chestnut. Some shells are light milky in color. A few species border on red, others are ashy. The range of color is about like that in the family Lynmaeidae, but there are no species known comparable to the greenish shell and purplish aperture of Bulimnea magasoma, the hand- somest of the fresh w^ater pulmonates. Zebra markings occur among the planorbids as among the lymnaeids. II. GENERAL ECOLOGY ECOLOGY now has such a wide significance and includes so many diverse subjects that it is necessary to define what is embraced under this term in this chapter. It is here made to include every- thing that affects the animal either from external or internal sources, in- cluding such subjects as the habitat, climate, altitude, chemical conditions of the water body, pollution, parasites, relations in food chains, reproduc- tion, development, etc. GENERAL ENVIRONMENTAL CONDITIONS Representatives of the family Planorbidae may be found in almost any body of fresh water, from the largest lakes to the smallest pools. Streams of all sizes harbor one or more species of the family. Certain groups, as Menetus, Planorhula, Tropicorbis, and some Gyraulus, are abundant in small pools which may become wholly or partially dry during diy seasons. ]\Iany of the large forms, such as Helisoma campamdatum, Helisoma corpulentum, Helisoma pilsbriji, and some varieties of Helisoma anceps, prefer larger bodies of water like the larger lakes. Helisoma trivolvis is common in small lakes or bays of larger lakes, in shallow areas where the shore is bordered by Typha and sedge, where food in the form of algae and other vegetation is abundant. In such habitats the snails may be seen with the foot attached to the under side of the surface film, the shell hanging downward, the animal busily eating such small organisms as may lie on the surface. In Florida, members of the subgenus Seminolina live in limestone pools of limited size. Almost all of the members of the family Planorbidae are littoral animals and are not usually found in water deeper than fifteen feet, the usual limit of rooted vegetation in water bodies. The maximum numbers occur in shallow areas not exceeding six feet in depth. A few inhabit deeper water and in the deep lakes of Europe and Asia, as lakes Geneva, Con- stance, and Leman in Switzerland, Lake Balaton in Hungary, and Lake Baikal in Siberia, they may occur in abysmal depths of from forty to 350 meters. In our own lakes, deep dredgings have produced no members of the family Planorbidae. The family is on the whole a distinctly shallow- water group. The Planorbidae are able to withstand unfavorable features of their environment better than most groups of mollusks, owing to their ability to breathe free air. Thus water of some alkalinity and salinity, as well as water containing sewage, may be used by these animals successfully as habitats. The Lymnaeas also share this ability to live under unfavorable conditions. It has been observed, however, that chemicals and oil, also wood wastes from factories, are inimical to the Planorbidae and Lym- naeidae and none have been seen which could resist this deadly type of habitat. Clear, cold mountain streams, especially if rapid, contain no planorbids, and usually no other mollusks, as far as personal observations have indicated. ]\Iany such in New England have been examined and a few in Idaho and ^Montana. 17 18 The Molluscan Family Plauorbidae Altitude does not seriously affect the distribution of the members of the family Planorbidae. In the Rocky Mountains they occur in lakes at alti- tudes of from 9,000 to 10,000 feet. Lake Titicaca, in Peru, which contains many mollusks, including a peculiar group of Planorbidae [Taphius) is at an altitude of 12,846 feet. The Swiss lakes are at comparatively high altitudes as are also some of the lakes of Asia which contain moUusk faunas of some size. Quite a literature has accumulated on the general ecology and par- ticular habitat relationship of the Planorbidae and other fresh-water mollusks. The remarks on tlie lymnaeas in the 1911 monograph on that family may be consulted with advantage. A number of special papers and books have been published which bear on this subject. These are listed in the bibliographv and may be consulted under the following names: Adams, 1909; Baker, F. C.^ 1910, 1911, 1916, 1918, 1920, 1922, 1924; Dybowski, 1875; Forel, 1869, 1874; Lindholm, 1909, Tavlor, J. W., 1894- 1900. VARIATIONS IN DIFFERENT ENVIRONMENTS The planorbid snails do not exhibit as much variation due to differences in the environment as do the Lymnaeidae (see Baker, 1911, pp. 29-32). The shell aperture often increases in size in large lake localities where the animal is subject to heavy wave action. This may be observed in Helisoma anceps percarinatum and in Helisoma anceps sayi which are lake dwellers in contrast with typical Helisoma anceps which is usually a river or creek inhabitant. Helisoma canipanulatum davisi is a small pool or swamp dweller while typical Helisoma campanulatum is a lake inhabitant and usually has a larger, more expanded aperture. Some species of this family show preferences for particular types of habitat. Thus Planorbula armigera is usually found in ephemeral pools or small bodies of water, or in pro- tected places in larger ponds and lakes. Planorbula crassilabris may often be found on a lake shore fully exposed to the waves. Promenetus umbili- catellus is an inhabitant of ditches, pools, and swampy places, while Pro- nienetus exacuous is usually found in larger bodies of water. Great variation is often seen in specimens of the same species from one habitat. Thus Helisoma duryi seminole, in Lake Eustis and Lake Griffin, Florida, varies from a typical planorboid form to a distinct physoid form by the elongation of the spire. In Lake Titicaca, in Peru, Taphius andecolus exhibits many variations in the form of the aperture, the whorls, and the condition of the umbilical region. In Carinifex the individual variations are numerous among specimens of one species from the same habitat. Among some of the species of the genus Australorbis of South America and the West Indies there is often great variation in the axial height of the shell. These examples might be greatly multiplied but enough have been pre- sented to show that variation is the rule among individuals of the family Planorbidae and that this variation may not be due alone to conditions of the environment but rather to the inherent 'law to vary' which is found in all living things. The family Planorbidae does not appear to offer as good a field for the distinguishing of the so-called habitat or ecological variations as does the familv Lvnmaeidae. General Ecology 19 LOCOMOTION Locomotion in the family Planorbidae is accomplished by the same means as in the family Lymnaeidae (see Baker, 1911, p. 32). The method most usually observed is that of gliding. Tlie planorbids have been observed to rise suddenly and descend abruptly, as do the lymnaeids, by varying the amount of air in or on the body or shell. The members of the family are usually very active, crawling about on aquarium walls quite rapidly, eat- ing everything in their i)ath. In locomotion the planorbids resemble the physas more than the lymnaeids. the latter usually being rather sluggish in motion. Young and immature planorbids are usually very active, much more so than fully mature individuals. FOOD Like the lymnaeids the food of the planorbids is largely vegetal. Little is known, however, concerning the food sujiply of this family. They have been observed eating pond-lily leaves (principally Castalia), Potamogeton, both the large floating leaf species and the submerged leaf species, and algae of various kinds. Both old and young snails will eat avidly of the algal scum which collects on the glass sides of an aquarium. The radula can be plainly seen, the animal using it from behind forward as described by Dr. v. Sterki many years ago. Stomachs and crops that have been opened and examined have usually contained a quantity of fine sand (especially in the crop) which probably helps in grinding the food before it enters the intestine. Ostracods (six in one specimen of Helisoma subcrenatum from Pass Lake, Fidalgo Island, Washington) , distomids, vegetable fibers, and a quantity of flocculent un- digested animal matter have been noted in the stomach. Specimens of Helisoma duryi seminole from Florida had the stomach and gizzard filled with small grains of sand and nothing else. Some planorbids are scavengers, though not to the extent observed among the lymnaeids. No evidences have come under observation indicating that the group is carnivorous (see Baker, 1911, p. 42 for notes on the food of lymnaeas). FOOD FOR OTHER ANIMALS Together with other fresh-water mollusks, the family Planorbidae fur- nishes food for a large number of other forms of animal life. Chief among the animal groups feeding on mollusks are certain species of fish (see F. C. Baker, 1916). Fresh-water snails, including planorbids, have been found in the stomachs of the following food and game fish: Whitefi.sh (Coregotms clupeaformis (Mitchill) ) Small Mouth Buffalo (Ictiobus bubahis (Raf.) ) Common Sucker {Catostomus commersonii (Lacepede) ) Yellow Bullhead (Ameiurus imtalus (LeSueur) ) Common Bullhead (Ameiurus nebidosus (LeSueur) ) Fre.sh\vater Drum (Aplodinotus grunniens Raf.) Pumpkinseed (Lepomis gibbosus (Linn.) ) Bluegill (Lepomis macrochirus Raf.) 20 The Molluscan Family Planorbidae Many smaller fish, not of direct value as food or game fish, are yet of great value as food for the larger food fish. Many of these include the planorbids and other fresh-water snails in their diet. Such small fish known to eat snails are: Fresh Water Killy {Fmululus diaphanus (LeSueur) ) Killifish (Fundulus dispar (Agassiz) ) Viviparous Top Minnow {Gamhusia affinis (Baird & Girard) ) Manitou Darter {Pcrcino caprodes zebra (Agassiz) ) Five species of the planorbids have been specifically identified in the stomach contents of fish. These are: Gyraulus parvus (Say) Gyraulus deflectus obliquiis (DeKay) Promenetus exacuous (Say) Helisoma anceps (Menke) Helisoma campanulatum (Say) Many species of birds, especially water birds, consume some mollusks in their diet. Ducks, such as the Lesser Scaup (Nyroca affinis (Eyt.) ) and others feeding in shallow water, eat fresh- water snails. The waders, such as the Upland Plover (Bartramia longicauda (Bechst.) ) and the Killdeer (Oxyechus vociferus (Linn.) ), feed on snails. The Red-winged Blackbird {Agclaius phoeniceus (Linn.) ) has been known to feed on a planorbid (probably a Gyraulus) . Other groups of animals which include fresh-water snails in their diet are turtles, frogs, newts and salamanders, crayfish, leeches, and dragonfly nymphs. It is quite probable that many other animals which frequent fresh-water snail habitats feed on the smaller species or the young of larger species. The stomach contents of many fish and birds have been listed as simply snails or Planorbis without identification of the species involved. It is obvious that the planorbids, and other snails of the fresh waters, are a valuable food source for the larger animals. LENGTH OF LIFE The life span of the members of the family Planorbidae is not definitely known. Specimens of Helisoma trivolvis lentum were hatched in an aquarium and lived sixteen months. At this time they were about 8 mm. in diameter and had four whorls. An adult lentum has five whorls and is about 20 mm. in diameter. It appears possible that these specimens would have attained full maturity in another year, or two and a half years from time of hatching. Helisoma duryi normale has been hatched in an aquarium and has lived for over a year. An adult Planorbarius corneus (the red snail) has been kept alive with goldfish for two years. Mature individuals of Helisoma trivolvis have remained alive for nearly two years in a well- balanced aquarium. Just how long any of the planorbids live in their natural habitat is not known, four or five years it is probable. The lymnaeids are said to live for three or four years. Experiments with the larger snails of the family Planorbidae, Helisoma particularly, would be of value. General Ecology 21 THE PLANORBIDAE AS HOSTS FOR PARASITIC WORMS The family Planorbidae furnishes some of the best examjiles of the role of snails in the life history of certain trematode worms known as flukes. A group of worms known as blood flukes {Schistosoma) cause serious dis- turbances in man. Three species are known from different parts of the world. These parasites require a mollusk as the host of the parthenogenetic generations of their life cycle. In this life cycle the Schistosoma in the human host lays eggs which are voided in the faeces or the urine. Eventu- ally the larvae in the eggs become clothed with a ciliated epithelium, and, on coming into water, the egg shell bursts and the miracidium escapes, whereupon it begins to swim about rapidly (Faust, 1932. p. 350). These miracidia are adapted to specific groups of snails. When in their swimming they reach the proximity of certain snails they show a specific response to that species of mollusk, probably due to a mucous secretion of the animal. In most cases they readily attack, and, in the course of half an hour or an hour, penetrate the soft tissues of the snail. In certain cases of other trematodes iClonorchis and Metagonimiis) , however, it is neces- sary for the embryonated eggs to be swallowed by the snail, whereupon they hatch in the lumen of the oesophagus, bore their way through the wall, ancl gradually migrate through lymph channels into the lymph spaces bathing the hepatic glands. In the meantime, they have metamorphosed into the simple sacculate sporocysts. These first generation sporocysts give rise to a parthogenetic progeny (either second generation sporocysts or rediae) . From this second generation there develops (also parthogeneti- cally), a progeny of larvae known as cercariae. Thus, from the penetration of a single miracidium there may be developed as many as ten thousand or more cercariae. Then later, on reaching maturity, they erupt from the tissues of the snail, and, either by direct or indirect routes, produce infection in human or reservoir hosts (from Faust, 1932, pp. 350-351). Although the three human species of blood flukes (Schistosoma) are closely related, they utilize entirely different species of mollusks for the l)arthenogenetic stages. Thus, Schistosoma haematobium, with a distribu- tion in northern Africa, the Congo Basin, the Sudan, ^Mesopotamia, Palestine, Sicily, Corsica, and possibly southern France, parasitizes species of the genera Bulinus and Physopsis. Schistosoma japonicum, with a distri- bution in China, Japan, Formosa, and the Philippine Islands, uses mem- bers of the genus Oncomelania. The third species. Schistosoma mansoni, occurring in the same localities in Africa as S. haematobium, is also found in northern South America and many of the West Indian islands whither it was brought from Africa by slaves during the days of the slave traffic. This species originally para- sitized small planorbids belonging to the genus now known as Afropla- norbis. In the West Indies a genus of large snails known as Australorbis is parasitized by the Schistosoma mansoni, which has become a serious pest in these regions. A genus of smaller snails, Tropicorbis, related to the African group Afroplanorbis, is also used as intermediate host. The small snails of the genus Drepanotrema have also been found with cercariae. Attempts to use the genus Helisoma as a host for Schistosoma mansoni 22 The MoUuscan Family Planorhidae were unsuccessful, although species of this genus are parasitized by other forms of trematode worms. Aguayo (1938, p. 210) has summarized the species of snails used as intermediate hosts by Schistosoma and other trematodes. Schistosoma haematobium is shown to use a species of planorbid, 'Planorbis dufuorii' as well as Bulinus and Physopsis. The Schistosoma mansoni intermediate hosts include Ajroplanorhis boissyi, A. pfeifferi, A. sudanicus, Australorbis glabratus, A. olivaceus, A. antiguensis, Tropicorbis centimetralis, and Dre- panotrema cultratus. The liver flukes of the genus Fasciola parasitize certain genera of Lymnaeidae [Radix, Pseudosuccinea, Fossaria, and Stagnicola) as well as one Physa, P. cubensis. The large fluke of the Orient, Fasciolopsis buski, which is closely related to Fasciola, uses only the small planorbids belonging to the old genus Segmentina which now includes the groups Pohjpylis, Heli- corbis, and Pingiella, true Segmentina not being found in the East. Four species are listed as intermediate hosts, Planorbis coenosus { = Helicorbis) , Segmentina hemaesphaenda {=Polypylis) , and \Seg)nentina sch)naken and '*S. nitidella' which have not yet been examined for their anatomy and hence their position is doubtful (probably Polypylis) . The value of cor- rect specific identifications of the intermediate hosts of these trematode worms is of- the first importance as has been clearly indicated by Ingles (1933) in a study of the parasites of frogs. Elaborate studies have been made by Dr. E. C. Faust of the Depart- ment of Tropical JVIedicinc in Tulane University, New Orleans, and by the late Dr. William A. Hoffman of the School of Tropical Medicine of the University of Puerto Rico, on various phases of the Schistosomiasis man- soni problem in Puerto Rico, where the mollusk Aiistralorbis glabratus (Say) (=Planorbis guadeloupensis Sowb.) is the intermediate host. For these studies see Faust, 1933; Hoffman and Faust, 1934; and Faust, Jones, and Hoffman, 1934. Papers by parasitologists in which molluscan hosts are mentioned are numerous. A few are here indicated. Faust (1918) has observed cercariae of four species in Helisoma trivolvis in Illinois and one species in Heli- soma sidjcrenatum (not trivolvis, as stated) in ^Montana (Faust 1917). In a list of the described cercariae of the United States ( 1919) Faust men- tions two species of the family Planorbidae, Planorbis parvus (Gyraulus) and Planorbis trivolvis (Helisomci) , as well as several Physidae and Lymnaeidae which are known hosts. Fourteen species of cercariae infest Helisoma trivolvis and three species occur in Gyraidus parvus. Miller (1936) found Helisoma trivolvis from Illinois and Helisoma trivolvis lentum (not lantum, typographical error) from Louisiana to be hosts of many American cercariae. O'Roke (1917) found Helisoma trivolvis (prob- ably the race lentum) carrying cercariae in Kansas, and McCormick (1923) found Helisoma trivolvis and Gyraulus parvus to be infested in Ohio. Ward (1918), in Ward and Whipple's Fresh-water Biology (pp. 365- 424), summarizes the cercarial stages of parasitic flatworms, gives keys for the determination of the larval stages and indicates the species of mollusks which have served as intermediate hosts. Physa, Lymnaea, and Planorbis are listed, including many of the Planorbidae. However, this text was compiled at the very beginning of studies on trematode life histories on this continent. More recently there have been numerous de- General Ecology 23 tailed studies on the stages in fresh-water snails. Many other works might he quoted but a sufficient number have been indicated to show the role played by the fresh- water snails, particularly the Planorbidae, in the life cycle of the trematode worms. Some additional titles are listed in the bibliographies accomj)anying the papers mentioned in this chapter. During the anatomical investigations made for this work careful note was made of the presence of larvae of trematode worms, principally cercariae and a few rediae. Over a thousand specimens of mollusks were examined but only a few contained parasitic worms. The following species, arranged under subfamilies, were observed to be infested. Subfamily Planorbinae No -spocimens of this subfamily were found with cercariae or rediae. Subfamily Segmentininae Scgmentina nitida from marshes in a meadow in Czneriakow, a suburb of Warsaw, Poland. Sent bj' Mr. A. Jankowski. Cercariae were abundant,- mainly in the ovotestis which was almost destroj^ed. All specimens examined were infested. Drepanutremn hoffmani from pond near Isabela, Puerto Rico. Sent by Dr. Wil- liam A. Hoffman. Heavily infested with stylet cercariae. Austmlorbi.fi glahratus from near San Juan, Puerto Rico. Sent by Dr. Hoffman. Various degrees of infestation. Subfamily Helisomatinae Helisomn anceps, from Unionville. Connecticut. Collected by F. C. Baker. One specimen with lung ca\ity filled with rediae and one specimen with cercariae in liver and genitalia. Helisoma trivolvis lentum, from near Urbana, Peoria, and St. Joseph, Illinois. Cercariae in liver and ovotestis. Helisoma subcrenatum from Cottonwood Pass, near Gypsum, Colorado. Sent by Junius Henderson. Four out of six specimens with cercariae in different parts of the body, mostly the li\'er. Some specimens from a sluggish creek one mile west of Devon, Montana, collected by J. Henderson and Hugo Rodeck, contained cercariae, mostly in the liver. Helisoma plexatum, from Teton River, north of Rexburg, Idaho, collected by J. Henderson; one out of six infected. Helisoma hornii, from Paul Lake, Kamloops District, British Columbia. Sent by Dr. D. S. Rawson, Uni^•ersity of Saskatchewan. About one-third were affected by cercariae. Helisoma pilsbryi from Chetek Lake, Barron Co., Wisconsin. Collected by F. C. Baker. Cercariae in eight specimens with the liver and ovote.stis mo.stly affected.. Helisoma corpulentum from Miles Bay, Lake of the Woods, Canada, Fall Lake, Ontario, Canada, and Knife Lake, St. Louis Co., Minnesota. Collected by Dr. A. R. Cahn. Many infested with cercariae. Heli^soma eorpulcntum multicostatum, from Lake Kahnipiminanikok, Ontario, Canada. Collected by Dr. A. R. Cahn. One out of six with cercariae. H(lisoma ivhiteavesi from Kashabowie Lake, Ontario, Canada. Collected by Dr. Cahn. One out of four infested with cercariae. Helisoma campanulatum wisconsinense from Pirate Island, Lake Nipissing, On- tario, Canada. From the Biological Boaixi of Canada. One out of five specimens with cercariae. Subfamily Planorbulinae Menelus cooperi callioglyptus from Quatana, Vancouver Island, British Co- lumbia. Received from Dr. W. A. Clemens. Two-thirds of the specimens examined (about a dozen) were infested with cercariae, in several examples almost consuming the liver, albumen gland, and ovotestis. In several specimens the cercariae were most numerous about the stomach. Several hundred were observed in some siJecimens. Ml 111 tux cooperi from small lakes on Mt. Con.stitution, Orcas Island, Puget Sound, Washington. Collected by Dr. Dale Foster. Of fifteen specimens examined, one contained cercariae. Meuetas dilutatus from L'nionville, Connecticut, fourteen miles west of Hartford. Collected by F. C. Baker. One specimen in sixteen contained cercariae. 24 The MoUuscan Family Planorhidae Menettis sampsoni from slough of Meramec River east of Stanton, Franklin Co., Missouri. Collected by Leslie Hubricht. Twelve out of fourteen specimens were in- fested with cercariae, the liver and genitalia being principally affected. In several specimens nearly all of the internal organs had been destroyed. Same species from small lake near Hutchins, Dallas Co., Texas, collected by Dr. E. P. Cheatum. Fifty per cent of specimens examined were affected by cercariae. Promenetus exacuous from small lake in Wainwright Park, Alberta, Canada. Re- ceived from A. LaRocque, Canadian National Museum, Ottawa. Nearly all specimens examined were infested with cercariae, some in the fore part of the bod}', many about the stomach, but mostly confined to the liver and genitalia. Specimens of exacuous from Maine, Wisconsin, Michigan, New York, and Ontario did not contain larval worms. It is unfortunate that parasitological assistance was not available when these anatomical studies were in progress in order that the particular species of parasitic trematode worms involved might have been ascertained. Many species of cercariae remain to be discovered from the tissues of planorbid and other fresh-water mollusks. The effect of fluke infestation on the anatomy of the snail is variable. The cercariae may infest only the liver, in which case, often, the cercariae finally leave the snail which recovers from the damage inflicted by the parasite. In many other cases, however, the liver, genitalia, and stomach are affected and in large measure destroyed. Specimens have been examined in which the genitalia were completely destroyed or the genitalia and liver obliterated. In one case (Menetus cooperi) , almost the whole snail was so filled with cercariae (several thousand) that the normal organization could not be distinguished, the cercariae being packed in the space occu- pied by the organs and in aggregation taking their form. This was par- ticularly true of the genitalia. Faust ( 1920, p. 79) has given a good account of the pathological changes in the gastropod liver due to fluke infestation. Wesenberg-Lund (1934) and ]\Iiriam Rothschild (1936) have recorded instances of gigantism in snails apparently attributable to trema- tode infections. Several parasitologists have essayed the role of conchologists in an endeavor to understand the specific limitations of the groups of molluscan species acting as hosts for i^arasitic trematode worms. Among these are the late Dr. Adolpho Lutz (1918) of the Instituto Oswaldo Cruz and Dr. A. Vianna Martins (1938) of the Laboratorio do Instituto Biologico Ezequiel Dias. Dr. Lutz describes all species under the common generic name Planorbis, the modern genera Australorbis and Tropicorbis being the principal groups discussed. In the main, the work of Dr. Lutz is good and the species have been carefully distinguished. The work of Dr. Martins is a study of the genus Australoi'bis of Pilsbry, based in part on the earlier work of Dr. Lutz. Unfortunately the two genera Tropicorbis and Austra- lorbis have been confused by this author and many species lumped under Australorbis, to which they have little relation anatomically. It is obvious that specific identifications must be accurately made if any value is to be attached to these forms as intermediate hosts of parasitic worms. In Part II of this work the recognized species, and also the synonyms, of species of both Australorbis and Tropicorbis, as well as of other groups, will be discussed and the species figured.* *The author's death came before he could finish Part II. However, 60 plates made for Part II are printed as an Appendix to this work (see page 213 et seq.). H.E.C. III. NIDIFICATION AND EMBRYOLOGICAL DEVELOPMENT THE EARLY STAGES of cell growth and development in the phi- norbids {Hclisonia trivolvis) have been well described and figured bv Holmes (1900, pp. 369-458). Crabb (1927, pp. 67-108) has described and figured the early stages of Lijmnaca stagnalis appressa ( =jugi(laris) and Lankester (1874) has given us the full development of the European Lymnaea stagnalis. More recently (1934) Lowrance has very fully de- scribed the early development of Stagjiicola kingi. Little work has been done, however, on the embryonic development of the different species of the family Planorbidae and especially on their nidification, period of development, and the time element in the growth of the voung animal in its shell.* A dozen or more aciuaria were operated during the years 1930 to 1934 and careful data were gathered concerning the period of egg deposition, number of capsules laid, changes taking place within the egg capsule, and growth of the young snails within the egg and after hatching. A. DEVELOPMENT OF Helisoma scalare (JAY) In 1932, Dr. E. A. Andrews, of the Johns Hopkins University, sent the writer a piece of pond lily leaf upon which was a large egg capsvde of Helisoma (Seminolina) scalare (Jay), containing twenty-eight eggs in vari- ous stages of development. This capsule was deposited in an aquarium but the parent came from Lake Butler, Florida. This egg capsule was observed as opi^iortunity afforded until all of the embryos were hatched or had died. From this capsule a fairly good idea of the development of this planorbid was obtained. Observations began when the specimen was received on March 2 and the last specimen was hatched on March 17. The different stages are figured on plate 51 and are described in the explanation of that plate. Development was observed to be sporadic in many of the eggs. There were resting stages between periods of great activity of rotation about the interior of the egg, the rotation beginning in this species the latter j^art of the gastrula stage, the second day of development, and becoming marked from the early trochophore stage. This rotation is caused by the vibration of the numerous cilia attached to the foot of the embryo (CL in figures). Observations on the egg capsule began on March 2, when twenty-eight fertile eggs were counted. The observations, made several times a day, showed the following degrees of development : March 2-3. 24 eg^cs in segmentation stages. 4 in early trochophore stage. 4. Same condition as on March 3. 5. 20 eggs in gastrula stage ; 4 in trochophore stage ; 4 in preveliger stage. 7. 18 in gastrula stage ; 5 in trochophore stage ; 3 in veliger stage ; 2 postveliger. 8. 18 in gastrula stage ; 4 trochophore ; 3 ^'eliger ; 3 embryos with shell. *After this manuscript was in press, a very significant experimental study, b.v H. B. Roney, on the development of Helisoma eggs, under controlled conditions, appeared in Ecology, v. 24, pp. 218-243.— H.J. V-C. 25 26 The MoUuscan Family Planorhidae March 10. 18 in gastrula stage ; 4 trochophore ; 3 veliger ; 3 embryos with shelL 11. 18 in gastrula stage ; 4 vehger ; 3 postvehger; 3 embryos with shelL 12. 18 in gastrula stage; 3 vehger; 4 postvehger; 3 embryos with shelh 13. 18 in gastrula stage; 3 veliger; 3 postvehger; 3 embryos with shell ; 1 hatched. 14. 18 in gastrula stage; 3 veliger; 3 postvehger; 2 embryos with shell; 1 hatched. 15. 18 in gastrula stage ; 2 veliger ; 2 postvehger ; 2 embryos with shell ; 2 hatched. 16. 18 in gastrula stage ; 2 postvehger ; 3 embryos with shell ; 1 hatched. 17. All hatched or dead, many of the gastrula stage filled with Protozoa. In the above table it will be observed that only ten embryos completed their development. Eighteen embryos did not continue their growth after reaching the gastrula stage, for what reason is not apparent. In the stage shown in fig. 9 on plate 51 the snail is very active, moving about in the egg and grazing like the adult snail. The radula can be seen working with its peculiar lapping motion, the heart is beating regularly, and the pul- monary siphon is functioning, for it can be seen to emit bubbles. One young snail four days out of the egg was transferred to an aquarium. This specimen was very active, crawling about the glass sides of the jar. The eyes were black and very conspicuous. Several of the embryos that completed their development showed the following history. EGG NUMBER 1 March 2-3. Segmentation and gastrula. March 10. Embrvo stage. Like fig. 10. Like fig. 2, 3. 11. Embryo stage. Like fig. 10. 4. Early trochophore stage. 12. Embryo stage. Like fig. 11. 5. Trochoiihore stage. 13. Young snail. Like fig. 12. 7. Posttrochophore stage. 14. Young snail. Like fig. 12. Like figs. 4, 5. 15. Young snail. Like fig. 12. 8. Veliger stage. Like figs. 6, 7. 16. Hatched from egg. Like fig. 13. 9. Veliger stage. Like fig. 9. EGG NUMBER 8 March 2-4. Early segmentation and ga.s- March 10. Veliger stage. Like fig. 9. trula stages. Like figs. 2, 3. 11. Embryo stage. Like fig. 10. 5. Po-sttrochophore stage. 12. Embryo stage. Like fig. 10. Like figs. 4, 5. 13. Young snail. Like fig. 12. 7. Veliger stage. Like fig. 6. 14. Young snail. Like fig. 13. 8. Veliger stage. Like fig. 6. 15. Young snail. Like fig. 13. 9. Veliger stage. Like figs. 7, 8. 16. Hatched. Like figs. 13, 14. Both of the above embryos completed their development in fifteen days. Probably some early cell divisions took place the day before observations began, which would increase the development period to sixteen days. The temperature of the room was 70-75 degrees Fahrenheit. The other eggs in this capsule showed approximately the same development. The embryo in egg number 5 migrated to egg number 6 at the late embryo stage and both embryos occupied the same chamber until they were hatched, three days later. Several adult Helisoma scalare received from Dr. Andrews, collected in Lake Butler, Florida, were placed in an aquarium where they bred and laid eggs which successfully completed their development. Eggs were first observed on Alarch 13 (see plate 52, fig. 1). The egg capsules were de- posited on the glass sides of the aquarium and were numbered so that development could be easily and accurately observed. Thirteen egg cap- sules were deposited early in Alarch: Xidification and Emhryological Development 27 Xo. 1. lOeggs, cap,'*ule3.5by2.5 mm. Xo. 8. 11 eggs, capsule 4.5 by 3.5 mm. 2. 6 eggs, capsule 3.5 by 2.5 mm. 9. 2 eggs, capsule 4.5 by 2.5 mm. 3. 8 eggs, capsule 3.0 by 3.0 mm. 10. 9 eggs, capsule 5.0 by 3.5 mm. 4. 10 eggs, capsule 5.0 by 3.0 mm. 11. 5 eggs, capsule 4.5 by 3.5 mm. 5. 4 eggs, capsule 3.5 by 2.5 mm. 12. 13 eggs, capsule 5.0 by 4.0 mm. 6. 10 eggs, capsule 4.5 by 3.5 mm. 13 14 eggs, capsule 5.0 by 3.5 mm. 7. 10 eggs, capsule 5.0 by 3.0 mm. Egg capsule No. 3 with eight eggs developed as follows: March 13. Freshly deposited capsule. March 22. Embryo with shell of about one 14. Early segmentation. whorl. 15. Gastrula stage. 23. Embryo with shell half filling 16. Gastrula and trochophore egg. stages. 24. Embryo with shell three- 17. Gastrula and trochophore fourths filling egg. stages. ■ 25. Embryo with shell almost 18. Trochophore and preveliger filling egg. stages. 26. Embryo with shell filling egg. 19. Veliger stage. 27. Four efnbrv'os hatched. 20. Early embryo stage. 28. Last embryo hatched. 21. Embryo stage. The period of development was fifteen days. Capsule Xo. 6, with ten eggs, occupied a longer period (18 daj's) in hatching. Capsule Xo. 8, with eleven eggs, had all embryos hatched in seventeen days, from ]March 15 to ]\Iarch 31. Capsule X"o. 11, with five eggs, de- veloped and hatched the young snails in thirteen days, from ^Nlarch 15 to ^Nlarch 27. All other capsules occupied fifteen to eighteen days. The shell when the young are hatched measures about 1.0 by 0.7 mm. About two weeks later (iVpril 2) six capsules were deposited measuring as follows (see plate 52, figs. 2, 3) : Capsule 4.5 by 3.0 mm. with 10 eggs. Capsule 5.0 by 3.0 mm. with 9 eggs. Capsule 5.5 by 3.0 mm. with 7 eggs. Capsule 5.0 by 3.0 mm. with 19 eggs. Capsule 6.0 by 4.0 mm. with 14 eggs. Capsule 5.0 by 3.0 mm. with 9 eggs. One capsule with nine eggs developed as follows, the process occupying but twelve days : April 2. Freshly deposited eggs. April 8. Post^•eliger and earlj' embrj'O 3. Segmentation. stages. 4. Segmentation and gastrula 9. Embryo with .small shell. stages. 10. Embryo filling egg. 5. Gastrula and trochophore stages. 11. Embryo filling egg. 6. Posttrochojihore and preveliger 12. Embryos hatching. stages. 13. Young snails all hatched. 7. Preveliger and veliger stages. On ^May 22 the aquarium was examined for its entire contents. There were ninety-six young snails of scalare only sixteen of which were living. There were three adult specimens measuring 8 to 10 mm. in length. These, curiously enough, were in shape more like Helisoma duryi seminole than typical scalare. The shells were very wide with broad spire and decided umbilicus. The young snails in the aquarium were approximately seven and one-half weeks old. A few of these were measured and the number of whorls was counted: Height 2.0; diameter 2.5 mm. Whorls 2. Height 3.0; diameter 3.0 mm. Whorls 2^>. Height 2.5; diameter 2.8 mm. Whorls 21/2- Height 2.5; diameter 2.8 mm. Whorls 21/4- 28 The Molluscan Family Planorhidae When hatched the shells usually measure 1 mm. in height and 0.7 mm. in diameter and have a trifle more than one whorl. The young scalare, therefore, had more than doubled in size in less than eight weeks. On August 15, after a hot summer, seven specimens remained in the aquarium. Five of these measured as follows: Height 4.7; diameter 5.0 mm. Whorls 3%. Height 4.0; diameter 4.1 mm. Whorls 3. Height 5.0; diameter 5.1 mm. Whorls 3. Height 6.0; diameter 5.0 mm. Whorls 3%. Height 6.0; diameter 6.0 mm. Wliorls 3^2. These measurements indicate that the shells had almost trebled in size in about twelve weeks, although but one more whorl was added. On June 26, during a hot period of weather, two adult snails of this species died, leaving one adult, which lived over winter isolated in a small aciuarium. On jMarch 5, 1933, several egg capsules were laid by this indi- vidual approximately nine months after its isolation. Two empty egg cap- sules were observed on the side of the aquarium and twenty-one young snails were crawling about. The young shells measured 2 mm. in height and 2.5 mm. in diameter and had two whorls. All li\'ed from March 5 to May 21 when three died. On June 25 the last adult died but nine of the young remained alive. On September 3, 1933, four of the young scalare were living. The young snails at this time, about twenty-three weeks old (160 days) measured 5.0 mm. in height and 4.5 mm. in diameter and had three and one-half whorls. Between September 3 and September 17 these young snails formed eighteen egg capsules containing the following number of eggs: 6, 11, 13, 9, 10, 5, 7, 7, 12, 11, 2, 5, 9, 10, 10, 7, 9, 7. Embryos in but two of the capsules com- pleted their development. The parent snails of this last brood, it will be noted, were the offspring of an isolated adult scalar^e. The young snails lived until January, 1934. The development of HeUso)}ia scalare is similar in many respects to that described by Lankester for Lymnaea stagnalis (1874) and by Lowrance (1934) for Stagnicola kingi. There are, of course, differences in the form of the embryos as would be expected in two such diverse families. Lowrance found that young snails of Stagnicola kingi hatched in from fourteen to sixteen days (p. 10) but that with increased temperature (26 degrees centigrade) this period was cut to from nine to eleven days. Liimnaea stagnalis may require as much as twenty days or more for development. B. NIDIFICATION AND DEVELOPMENT IN OTHER SPECIES OF Helisoma Plates 51 and 52 Living material belonging to five additional species and races of Helisoma was studied in aquaria during the years 1931, 1932, and 1933. The species included were: Helisoma trivolvis lentum (Say) Helisomn trivolvis fallax (Haldeman) Helisoma duryi normale Pilsbry Helisoma duryi eudiscus Pil.sbry Helisoma tenue calijorniense F. C. Baker Nidification and Eutbnjological Develojwient 29 Several species were from different localities and these as well as each race were kei)t in separate aciuaria. Observations were made several times each day at intervals of three or four hours. Each jar was labeled and the egg capsules lettered or numbered as they were deposited by the animals. Notes were kept of developments in each capsule. The data which follow have been condensed from the original notes. The information sought in these studies was to ascertain the time re- quired for development and the rate of growth of the shells of the young snails during their life in the aquaria. [a] Self-fertilization or Autofecundation That self-fertilization or autofecundation is possible among the fresh- water pulmonates has been suggested by several zoologists during the past hundred years or more, but until comparatively recent time few experi- ments have been carried on to test the reality of this method of reproduc- tion. Colton (1912. \). 173; 1918, p. 48) has shown that Lymnaea, Physa, and several groups of Planorbidae {Gyraulus, Menetus) lay fertile eggs by this method when isolated. Crabb (1927) has presented elaborate data on this subject, and more recently Larambergue (1939) has issued an elaborate monograph particularly relating to Bidimis contortus. On pages 541-543 he ]iresented a list which includes all of the authentic exami)les of autofecundation. This list includes all families of Basommatophora as well as a few among the Stylommatophora. Crabb (1927) studied Lymnaea stagnalis appressa {=jugularis) to determine whether snails kept in strict isolation reproduced by self-fertilization or b}' parthenogenesis. His con- clusions were that there was no evidence of parthenogenesis in this snail. It is to be noted, however, that reproduction by parthenogenesis does occur in some groups of snails. Boycott (1919) has asserted that Palude- strina jenkinsi develops by this method. ]More recently Van Cleave ( 1937) and ]\Iattox (1937, 1938) have shown that the viviparoid snail Campeloma rufutn develops solely by parthenogenesis although other species of the genus have been found to be bisexual. The reproductive method in Campe- loma was observed by morphological and histological studies and there is no question concerning the parthenogenetic method of reproduction in the species examined. Some years ago, Chadwick ( 1903, p. 265) conducted some interesting exi)eriments on Planorbis vorte.v, a common English planorbid. On Feb- ruary 2, 1901, he isolated an adult specimen in a jar three-fourths filled with boiled water, a small quantity of weed was introduced, the rest of the jar was filled with pure oxygen and the vessel was perfectly sealed. It remained in this condition for eighteen months, or until August, 1902. In June, 1902, aften sixteen months of complete isolation, the snail deposited some eggs which were hatched in early July, producing twenty-seven young snails, many of which were still thriving under these confined conditions on December 10, 1902. In evaluating this set of observations, and many others along this line, it should be remarked that only those experiments in which individual eggs were isolated have any conclusive value in estab- lishing the occurrence of self-fertilization. This is especially true when forms are considered for which there are no observations as to the length of time the spermatozoa remain viable following copulation. 30 The Molluscan Family Planorhidae Crabb states (1927, p. 91) that self-fertilization is the normal method of rei^roduction in Lynmaea and other fresli-water pulmonates and that cross-fertilization seldom or never occurs. With this general statement the writer can not fully concur. It is doubtless true in many cases of reproduc- tion during isolation but that it is the chief method among free snails when in aggregation in their native environment or even in the laboratory is scarcely possible. The writer has observed many species of Lynniaea, Physa, and the planorbids in coitu. If the method of reproduction men- tioned by Crabb is the chief or possibly the only method, why should the male portion of the genitalia be so elaborately developed with prostate and the penial complex provided with such diverse accessories in its makeup? The spermatheca has been found to contain a spermatophore containing sperm which was obviously deposited during copulation. Self-copulation probably occurs when a snail is isolated, at least in those species having a penial complex of sufficient length to reach the female opening, which is the case in many species of the Planorbidae. Crabb states that he was unable to raise progeny from isolated Pla- norbis trivolvis iHelisoma) , four individuals being carefully reared in iso- lation for 377 days without the laying of a single egg capsule. Ten to fifteen small empty egg masses were deposited. Even the control culture, consisting of two snails, formed no capsules. Lymnaca stagnalis, on the contrary, was very prolific. My isolated laboratory stock lays about e\-ery third day for a period of about twenty- five days, rests a few days, then begins another cycle of laying. This is continued throughout the year. Of fifty-four L.s.appressa isolated from the same egg mass, seven laid their first eggs fifty-eight days after hatching. However, they do not reach their maximum laving capacity until they are about one hundred days old (Crabb, p. 73). Colton's experiments on Lynmaea {Pseudosuccinea) columella indicated that the interval between hatching and egg laying was widely variable (1912, ]i. 175). Thirteen isolated individuals had the following interval between hatching and egg laying: 32, 26, 35. 49, 58, 92, 50, 50, 56, 57, 63, 74, and 74 days. Twenty-six days was the shortest interval and ninety-two days the longest interval. In the family Planorbidae the intervals are much longer, not only of the specimens placed in isolation, but for those in aggregation. Helisoma scalare laid thirteen egg capsules in early March, 1932. In early April, six additional capsules were produced. An isolated individual which lived over winter (nine months) without egg laying, deposited two fertile egg capsules on March 5, 1933. Between September 3 and September 17 the young snails, 160 days old, laid eighteen egg capsules containing from six to thirteen eggs in each capsule. Specimens of Helisoma trivolvis lentum were placed in aquaria in 1930. On February 16, 1931, a capsule was laid, on February 22 four capsules were deposited and on March 7 two capsules were laid. No other eggs were laid by these specimens which lived until Se]it ember 17, 1933, or a period of 943 days. A young specimen from the parent lentum. was isolated Janu- ary 16, 1932. It was about 325 days old. Between May 27 and June 9, 1932, this individual, after inhabiting the aquarium for 132 days, laid twenty egg capsules aggregating 325 eggs. On June 20, 1932, the parent snail was removed to another aquarium and on June 22 laid two egg cap- Nidification and E tnbryological Developinent 31 siiles and on June 27 deposited two more capsules. These capsules were laid fifteen and twenty days after the large laying period in the first aquarium. Two-thirds of the eggs laid completed their development. A few of the second generation remained alive for about two years but laid no egg capsules. These examples seem to indicate that the large planorbids do not breed as often as do the lynmaeids and are not as available for studies in de- velopment as are members of the Lymnaeidae. Just how the smaller species of the genera Menetus, Gyraulus, and Tropicorbis would react to such investigations is not known.* It is probable that had Crabb kept his Heli- soiita trivolvis longer they might ultimately have laid eggs. [b] The Development of Helisoma The notes that follow describe some of the results of aquarium observa- tions on a few of the species of the genus Helisoma. No attempt has been made to go into the finer details of embryological development. This has been done by Holmes (1900) and others. [1] Helisoma trivolvis lentum (Say) SoNoral .spcfimoiis of the Ic ntiim race were received in 1930 from Dr. E. C. Faust of the Tulane Medical School, New Orleans. They were collected from the canal at New Orleans. This city is also Say's original locality for this species. The snails were placed in aquaria and kept under observation for several years. On February 16, 1931, an egg capsule was observed, apparently freshly laid, with twenty-five eggs. It measured 7.5 by 6.0 mm. On February 22 four additional egg capsules were laid, one 4 by 3.5 mm. with nine eggs, one 7 by 4 mm. with fourteen eggs, one 9 by 4.5 mm. with nineteen eggs, and one 10 by 4.5 mm. with twenty-four eggs. On March 7, two other egg capsules were observed, one with fifteen eggs and the other with nineteen eggs. All eggs were fertile and contained embryos in the early stages of development. On September 12, 1931, twenty-five young snails were counted, ranging in diameter from 4.5 mm. with two and one-foui'th whorls to 16 mm. with four whorls. On No- vember 28, 1931, nineteen specimens were counted ranging in size from 5.5 mm. in diameter with three whorls to 14 mm. with four and one-fourth whorls. On January 16, 1932, the nineteen specimens were again measured, the smallest being 5.5 mm. in diameter with three whorls and the largest 14 mm. with four and one-fourth whorls. On March 19, 1932, the same number of specimens remained in the aquarium, the smallest being 6 mm. in diameter with three and one-fourth whorls and the largest 14.5 mm. with foiu' and one-fourth whorls. On June 10, 1932, only fourteen specimens remained in the aquarium. fi-\"c ha\ing died. The smallest was 6.5 mm. in diameter and had three and one-foiu'th whorls and the largest was 12.5 mm. with four whorls. August 15, 1932, only six specimens were alive, the smallest 6.5 mm. in diameter and the largest 10 mm. in diameter. On October 23 and December 26 the six specimens were still alive. Their size had not increased. On March 5, 1933, five specimens were living, the largest 10.5 mm. in diameter with four whorls. On June 25, 1933, three were li^■ing, the largest being 11 mm. in diameter with four and one-foin-th whorls. On September 17, 1933, two specimens were living. These two specimens had li^•ed o\er two years in the aquarium. Of the original 125 eggs laid in February and March, 1931, only 25 young snails survived until September, 1931, and onl.y two snails were alive two and one-half years later. Mortality among the young snails appears to be heavy in their earlj' postembry- onic life. *Rearing methods for securing uninfected snails to be used in life history studies on parasitic worms have been practiced in many parasitological laboratories. W. H. Krull (1931) has published the jjrocedure for successful rearing of Gyrauliis parvus and found that this species may be reared to full size in from four to five weeks under laboratory conditions (Occas. Pap. Mus. Zool., Uni. Michigan, No. 226).— H.J.V-C. 32 The Molluscan Family Planorbidae [2] Helisovna trivolvis fallax (Haldeman) October 2, 1931, fifteen specimens of tliis race, collectecl near Cambridge, Massa- chusetts, were recei\'ed from Dr. Harold A. Rehder, then in Harvard University (now x\ssistant Curator of Mollusca, United States National Museum). Egg capsules were observed February 6. 1932, one measuring 4.5 by 3.5 mm. and containing six eggs, and one 5.6 by 7 mm. with thirteen eggs. Tlie eggs of both capsules passed through their development and were hatched by February 12. On February 28 another capsule was laid measuring 5.2 by 4 mm., containing ten eggs, but was eaten by Protozoa after three days of development. March 4 a capsule was laid measuring 5 by 6 mm. with twelve eggs, and on Maich 10 another capsule was laid, 3.5 by 5.5 mm., containing eleven eggs. On March 13 a capsule containing nine eggs was observed. On March 19, twenty-two young and five adult snails were counted in the aquarium, the young ranging in size from 1.8 mm. to 3 mm. in diameter. An examination on May 22 revealed seventeen young snails living. All of the adult snails were dead. The li\ing young snails measured as follows: 2 specimens 2.5 mm. in diameter with 2 whoils. 3 specimens 2.5 mm. in diameter with 2^/4 whorls. 1 specimen 2.8 mm. in diameter with 2% whorls. 3 specimens 3 mm. in diameter with 2V2 whorls. 1 specimen 3.2 mm. in diameter with 2i/{> whorls. 4 specimens 3.5 mm. in diameter with 3 whorls. 1 specimen 3.8 mm. in diameter with 3 whorls. 2 specimens 4 mm. in diameter with 3 whorls. On June 26, 1932, the seventeen young fallnx were still alive. On August 15 there were fourteen living young snails which measured as follows: 1 specimen 2 mm. in diameter with 2 whorls. 1 specimen 3 mm. in diameter with 2 whorls. 1 specimen 3.5 mm. in diameter with 2i/-> whorls. 2 specimens 4 mm. in diameter with 2^2 whorls. 5 specimens 4.5 nun. in diameter with 3 whorls. 2 specimens 5 mm. in diameter with 3 whorls. 2 specimens 5 mm. in diameter with 3M whorls. On October 23, 1932, only four young jaUax remained living: 1 specimen 3.5 mm. in diameter with 2^/^ whorls. 1 specimen 4.5 mm. in diameter with 3 whorls. 1 specimen 5 mm. in diameter with 3 whorls. 1 specimen 5 mm. in diameter with 3^4 whorls. On March 1, 1933, these four snails were still living and measured as follows: 1 specimen 4 mm. in diameter with 2^2 whorls. 1 specimen 5 mm. in diameter with 3 whorls. 1 specimen 5.2 mm. in diameter with SMi whorls. 1 specimen 5.5 mm. in diameter with 3^/4 whorls. On May 1, 1933, only three living snails remained: 1 specimen 4.9 nun. in diameter with 3 whorls. 1 specimen 5.5 mm. in diameter with 31A whorls. 1 specimen 5.6 mm. in diameter with Sy^ whorls. On June 25 one young snail remained which measured 6 mm. in diameter and had three and one-half whorls. This small subspecies of HeUsoma trivolvis lived in the aquarium 495 days or about seventeen months. It grew from a size of 1.5 mm. in diameter when hatched to 6 mm. when it died, and increased from one and one-fourth to three and one-half whorls. Adult fallax measures 15 mm. in diameter and has five full whorls. The last remaining young was, therefore, somewhat more than one-third grown. Full maturity would i^robably have been attained the third year after hatching. Conclusions of this sort, in which length of life span is estimated from growth rates in aquaria, are only tentative and are possibly subject to considerable error. Very early experiments on snail development tended to show that the size of reared snails is influenced by the volume of the water and the container in which they grew. Conclusive evidence of rate of growth in natvu-e could be determined by measuring representative samples, from normal habitats, taken periodically as practiced by Van Cleave (1932) and his students in the interpretation of life history data. Nidificatio)} (Did Eiiibnjological Development 33 [3] HeXisoma duryi noymalt Pilsbry Specimens of this planorbid, collected on the Tamianii Trail, forty miles west of Miami, Florida, were sent to the writer by Mr. W. F. Shay of the Department of Science, Normandy High School, St. Louis. They were placed in aciuaria in January, 1931. On January 31 several egg capsules were observed, one containing fifteen em- bryos in various stages of development, three in veliger stage and twelve with well- formed shells. B.y February 2, eleven snails had been hatched and were crawling on the glass sides of the aquarium. By February 6 most of the veliger larvae had been hatched. Another capsule contained fifteen eggs with one veliger stage, one gastrula stage and thirteen embryos with well-formed shells. These latter hatched on Feb- ruary 4. Another capsule contained ten eggs, five embryos with partly formed shells and fi\e embryos with fully formed shells. These were hatched by February 5. On September 1, 1931, three capsules were observed on the side of the aquarium, one with nine eggs, 7 by 4.5 mm. in area, one with ten eggs, 6 by 5 mm. and one with eight eggs, 5.7 by 3.2 mm. On September 12, two additional capsules were deposited, one with seven eggs (6 by 3.2 mm. in area) and one with four eggs (4.7 by 2.7 mm.). Of the first series of three capsules, two died and were eaten by Protozoa and one completed its development. Of the second set, one capsule carried out its full de- velopment. In this capsule, the veliger stage was reached on September 15 and the embryo with a well-formed shell on September 19. On September 20, the four snails were actively feeding in the egg capsule, the walls of the egg capsules were broken, and the snails were crawling about in the broken interior. On September 21, the snails had left the egg capsule and were feeding on the side of the aquarium. It is probable that this capsule had been laid for a day or two before first observed because the interval of nine or ten days seems too short for comjilete development. On January 17, 1932, a recently laid capsule containing sixteen eggs was discovered and was obser\ed until all of the embryos had been hatched (see plate 42, fig. 12). In this cajisule fifteen days elapsed between early segmentation and exit from the egg. By the middle of February the young snails measiu'ed 1.1 by 1 mm. and actively glided about the aquarium. The body in the shell is pinkish, the foot hyaline, slightly yellowish, the liver brownish, and the eyes black and prominent. The tentacles are long and mobile. The radula can be plainly seen at work and the jaw appears blackish through the translucent head. From the aboA'e capsule and from several others hatched at about the same time, forty young snails were released in February. Observations were made on the shells several times in March and April. On May 22 there were seven living snails and thirty-three empty shells, indicating that mortality had been heavy, principally during the month of May. The seven living snails had the following shell measurements: 1 specimen 1.5 mm. in diameter with 2 whorls. 1 specimen 2.5 mm. in diameter with 2^-2 whorls. 1 specimen 2.8 mm. in diameter with 3 whorls. 1 specimen 3.4 mm. in diameter with 2->4 whorls. 2 specimens 3.5 mm. in diameter with 3 whorls. 1 specimen 4 mm. in diameter with 3% whorls. On June 26 the seven snails were still alive. By August 15 one had died. The six snails gave the following measurements: 2 specimens 4 mm. in diameter with 3 whorls. 2 specimens 4.5 mm. in diameter with ZYi whorls. 1 specimen 5 mm. in diameter with 3^4 whorls. 1 specimen 5.5 mm. in diameter with 3^/4 whorls. On December 26, 1932, but four snails remained alive. These showed the meas- vu'ements below: , • . • i- , vu o u i 1 specimen 4 mm. m diameter with 3 whorls. 1 specimen 5 mm. in diameter with 3^/4 whorls. 1 specimen 5.2 mm. in diameter with 3'!4 whorls. 1 specimen 6 mm. in diameter with 3^/i> whorls. On March 12, 1933, three snails were living which mea.sured as follows: 1 specimen 4.8 mm. in diameter with 3 whorls. 1 specimen 5.7 mm. in diameter with 3Vi whorls. 1 s])eciinen 6.1 mm. in diameter with 3Vi! whorls. 34 The Molluscan Family Plaiwrbidae On June 25, 1933, the same three snails showed some growth: 1 specimen 5.5 mm. in diameter with 3% whorls. 1 specimen 6.5 mm. in diameter with 3^/i> whorls. 1 specimen 6.5 mm. in diameter with S^/v; whorls. On August 6, 1933, but two snails remained alive. These measured: 1 specimen 6 mm. in diameter with 3^2 whorls. 1 specimen 6.8 mm. in diameter with 3^-2 whoi-ls. These 3^oung snails li^•ed 570 to 580 days after hatching and increased in diameter from 1.1 mm. to 6.8 mm. and in number of whorls from one to three and a half. An adult nor male measures about 20 mm. in diameter and has five whorls, so that the young snails were about one-thiixl grown after a development period of one year and seven months. If this growth is normal, it must require three or four years for this race to attain maturity, unless there is considerable acceleration in growth during the second or third years. The tem])erature in which the young snails were reared was ordinary room heat between 70 and 75 degrees F. This temperature reached 90 degrees or more in the hot .summer months. The matter of food is also important since only filamentous algae were jilaccd in the aquaria, the snails feeding mostly, howe\er, on the green algal deposit which formed on the glass sides of the aquaria. [4} HeXisoma duryi ^udiscus Pilsbry Si>ccimens of this race of duryi were received from Mr. T. Van Hyning, of the Florida State Museum, collected at Silver Springs, Marion County. They were re- ceived at the laboratory on October 2, 1931. On December 13 an egg capsule was laid measuring 2 by 2.5 mm. in area with five eggs. On February 6, 1932, another capsule was laid measuring 2 by 4 nmi. with nine eggs, and on February 12 a capsule with seven eggs. On February 10 a large capsule measuring 5 by 4 mm. was deposited containing twelve eggs. One capsule (Feb. 10) developed to the gastrula stage and then ceased growth. Another was disintegrated and the space was filled by Protozoa. A third capsule (Feb. 12) completed its development, all of the embryos being hatched. A single adult cudisciLS was left in the aquarium and on June 11, 119 days after the laying of the last egg capsules, egg laying began again with the deposition of a capsule measuring 4 b.v 3.5 mm. and containing two eggs, each egg 1 mm. in diameter. On Jime 13 the eggs had reached the gastrula stage. From June 14 to June 26 the eggs remained in the same stage and at the last date the eggs appeared to disintegrate. [5] HeXisotna tenue. cali^oyr\,i&ns& F. C. Baker Specimens of this race were recei\ed from Dr. S. S. Berry, collected from Prospect Park, near Redlands, San Bernardino Mts., California. They were placed in an aquari- um on February 12, 1932, and laid nine egg capsules on the next day. The nine capsules contained 199 eggs as noted below: No. 1. 4 by 4 mm. in diameter containing 15 eggs. 2. 5 by 3.5 mm. in diameter containing 18 eggs. 3. 4 by 7 mm. in diameter containing 21 eggs. 4. 6 by 3.5 mm. in diameter containing 28 eggs. 5. 4 by 5 nun. in diameter containing 15 eggs. 6. 4 by 4 mm. in diameter containing 11 eggs. 7. 4 by 7.5 mm. in diameter containing 27 eggs. 8. 4.5 by 7 mm. in diameter containing 26 eggs. 9. 5 by 8 mm. in diameter containing 38 eggs. Development was fairl.v regular and occupied fifteen days, from February 13 until February 28. A typical development is indicated below: Feb. 14. Segmentation begun. Feb. 23. Embryos with shell forming. 15. Segmentation ancl gastrula stages. 24. Embryos with shell ^3 filling 16. Gastrula and trochophore stages. membrane. 17. Trochophore and preveliger 25. Embryos with shell filling % stages. and y^ of membrane. 18. Early veliger stages. 26. Embiyos with shell filling % of 19. Veliger stages. membrane. 20. Early embryo stages. 27. Embiyos with shell completely 21. Early embryo stages. filling membrane. 22. Embryos with shell forming. 28. All hatched. Nidification and Emhnjoloykal Development 35 On February 15 three cajjsules were laid by the adult snails. They contained three, eleven, and thirteen eggs respectively and development occupied thirteen to fifteen days, from February 28 until March 12. On February 18 a capsule 9 by 6 mm. was laid containing forty eggs, and on February 20 four cap.sules were deposited meas- uring 6 by 5, 9 b\' 6, 6 by 5, and 6 by 4.5 mm. They contained thirty-five, thirty-three, twenty-eight, and twenty eggs respectively. On March 1 and 2, two capsules were laid containing thirty-one and twenty-three eggs. All of these eggs completed their de- velopment in from twelve to fourteen da.ys. On June 5, 1932, the aquarium was examined and the shells counted and measured. There were ninety-six li\ing young snails and forty-fi\e empty shells, 141 specimens in all which had hatched from the capsules enumerated above. The living 3'oung snails gave the following measurements: 8 specimens 1.5 mm. in diameter with 1V> whorls. 18 specimens 2.0 mm. in diameter with 2 whorls. 3 specimens 2.3 mm. in diameter witli 2 whoi'ls. ■ 40 specimens 2.5 mm. in diameter with 2 whorls. 20 specimens 3.0 mm. in diameter with 2 whorls. 6 specimens 3.0 mm. in diameter with 2^/l> whorls. 1 specimen 4.0 mm. in diameter with 21-) whorls. Between June 5 and June 26, fifty-four young snails died, leaving fort3'-two active young and three adult .snails. On August 15, only fourteen young snails were alive, the great mortality being largely due to the very hot summer. The measurements of these survivors are shown below: 1 specimen 2.1 mm. in diameter with 2 whorls. 2 specimens 2.5 mm. in diameter with 2 whorls. 3 specimens 3.0 mm. in diameter with 2i/-i w'horls. 6 specimens 3.5 mm. in diameter with 2V-> whorls. 2 specimens 4.0 mm. in diameter with 2% whorls. On October 23. 1932, two young snails died leaving twelve active 3'oung. On December 28, 1932, four additional snails died lea\ing eight young which gave the following measurements : 1 specimen 3.5 mm. in diameter with 2V2 whorls. 1 specimen 4.0 mm. in diameter with 2y-2 whorls. 1 .specimen 4.0 mm. in diameter with 3 whorls. 1 specimen 4.2 mm. in diameter with 3 whorls. 3 specimens 4.5 mm. in diameter with 3 whorls. 1 specimen 4.9 mm. in diameter with 3 whorls. On March 12, 1933, only five young .snails remained alive, as noted below: 1 specimen 4.0 mm. in diameter with 21^ whorls. 1 specimen 3.5 mm. in diameter with 3 whorls. 2 sjjecimens 5.0 mm. in diameter with 3 whorls. 1 specimen 5.0 mm. in diameter with 314 whorls. On May 1, 1933, but two specimens remamed alive. mea.suring: 1 specimen 4.0 mm. in diameter with 3 whorls. 1 specimen 5.2 mm. in diameter with 3^/4 whorls. On June 25, 1933, one specimen only remained, mea.suring 6.1 mm. in diameter with three and one-half whorls. This specimen had li\ed from February 28. 1932, until June 25. 1933, an interval of 482 days or sixteen months. It had grown from a diameter of 0.8 mm. to 6.1 mm. and the whorls increased from one to three and one-half. Adult californiense measures 20 nmi. in diameter and has five whorls which would indicate that the young specimen sixteen months old had made about one-third of its growth. As in the cases of the other species described in this chapter, factors of volume of water, food, and temperature maj^ have retarded the normal growth of the young of this race. At this ratio full maturity would be attained between the third and fourth years of life. [6] Other Records of Egg Laying HcUfiODUi pilshryi infracnrinatiun F. C. Baker. Sjiecimens of this species were re- ceived from Mr. A. LaRocque, of the Canadian National Mu.sevmi. They were collected in the Rideau River near Ottawa. Canada. On June 20 two egg cap.sules were deposited each measuring 6 by 4.5 mm. in size and containing eighteen and twenty eggs. On 36 The Molluscan Family Planorhidae May 7 a capsule was laid which measured 7 by 4.5 mm. in area and contained twenty- two eggs. Development was not obser\ed. Hclisoma traskii (Lea). Six shells of this species, preserved in alcohol, received from Mr. Stanley Siegfus of Bakersfield, California, had eleven egg capsules on the shells, containing 394 eggs. A capsule containing fifty eggs is figured (13) on plate 52. The specimens were from the Buena Vista Canal, outlet of Kern Lake, California, near the type locality for traskii. The capsules and eggs are noted below: 1 shell with 2 capsules containing 16 and 24 eggs. 1 shell with 2 capsules containing 45 and 42 eggs. 1 shell with 1 capsule containing 10 eggs. 1 shell with 2 capsules containing 35 and 85 eggs. 1 shell with 3 capsules containing 35. 22. and 20 eggs. 1 shell with 1 capsule containing 50 eggs. Mociuin-Tandon (1855, pp. 425-439) collected egg capsules from water bodies in the environs of Toulouse, France, and obser\ed the development of some of the embryos. Some of his observations are recorded below : Segrnentina nitida (Miiller). Nine egg capsules containing 3, 4, 5, 6, 7, and 8 eggs, the capsules measuring 0.25 to 1.5 mm. in diameter. Development occupied ten to twelve daj^s. Hippeutis jontanus (Lightfoot). Several capsules with 3, 4, 5, and rarely 6 eggs in each capsule. Gyrorbis co7)iplanatus (Linn.) {^ Planorbis planorbis (Linn.)). Eight capsules containing 10, 11, 13, 16, 17, and 21 eggs. Gyrorbis carinatus (Beck in Moller) { ^ Plnnorbis cnrinatus). Capsules contain- ing ten to twenty eggs each. Development occupied ten to fifteen days. Gyrorbis vortex (Linn.) {^^ Anisus vortex (Linn.) ). Ten to twelve eggs in a cap- sule which were 4 mm. in diameter. Development required ten to twelve days. Plnnorbis albus Miiller {^ Gyraulus albus (Miiller)). Capsules 3 to 4 mm. in diameter containing four to ten eggs. Planorbis contortus Linn. {= Bathyomphahis contort us (Linn.) ). Capsules 3 mm. in diameter containing six to eight eggs. Development occupied ten to twelve days. Planorbis corneus (Linn.) {^ Planorbarius corneus (Linn.)). Egg capsules 9, 11, 12, 13, and 15 mm. in diameter containing twelve to forty eggs each. Development required fifteen to sixteen days. Brooks (1880) has recorded the early stages in the development of the small snail Gyrauhis parvus (Say) {= Planorbis parvus Say). IV. DISTRIBUTION IN TIME AND SPACE A. GEOLOGICAL HISTORY AND DISTRIBUTION THE ANCESTRY of the Planorbidae, as of other members of the puhnonate molkisks, is shrouded in mystery. It is said that the ancestors of the Planorbidae, as of other groups of the Basom- matophora, were originally aquatic, then migrated to the land and finally again returned to aquatic habitats. Perhaps this was accomplished through such groups as the Auriculidae {Carychium for example) which have the Basommatophorous organization but inhabit the land. In America the family apparently first appears in the Morrison forma- tion which is considered of Jurassic or Early Cretaceous age, probably Jurassic. In Europe, a species, Planorbis mendipensis IVIoore, is known from the Liassic of England. The family is not uncommon in the Bear River formation, believed to be at the top of the Lower Cretaceous (Comanchean), or at the base of the Upper Cretaceous, and also in the several divisions known to belong to the Upper Cretaceous, as Judith River, Belly River, and others. During Tertiary time the family was well represented. Eocene, ]\Iiocene, Oligocene, and Pliocene formations have yielded many characteristic species. The Pleistocene planorbid fauna is practically the same as the recent fauna. As the few specimens of planorbid shells from Jurassic or Lower Cre- taceous time are not notably different in general characteristics from those of later geological periods or from the modern fauna, it is obvious that the family in some form must have existed in earlier strata, Triassic and Carboniferous (Pennsylvanian and Mississippian) . A Physa (prisca Wol- cott) and other fresh-water groups are reported from the Mississippian of Nevada and fresh-water and land mollusks are known from various locali- ties from strata of Pennsylvanian age. Planorbids, however, have not yet been reported from these older geological periods. In Europe this family is fairly common in rocks of IMesozoic and Cenozoic age, but earlier records are very few in number. A Triassic pla- norbid has already been mentioned. In the Upper Oolite another species appears, Planorbis fisheri Forbes. In the Eocene a number of species of this family occur, and in the Oligocene more than eleven species are known. The family is not uncommon in later periods. On the continent a large number of species and races of this family have been recorded from nearly all of the later geological periods. Wenz (1923) has listed all of these but many of the species have obviously been placed in the wrong genera, especially some of the large forms which are listed under the genus Planorbina , for it does not occur in Euroi^e. It is cjuite probable that these large species are members of the genus Planorbarius and are related to the large Planorbarius corneus so common in the recent fauna. In America (see Henderson, 1935) sixty-three species of fossil planor- bids have been described. Of these two are of Jurassic or Comanchean age, 37 38 The Molluscan Family Plaiwrbidae two from Comanchean, five from Upper Cretaceous, eight from Eocene, six from Oligocene, five from Miocene, thirty from Pliocene, and five simply described as 'Tertiary.' It is obviously very difficult to place fossil mollusks in appropriate genera in a classification based on anatomical characteristics. Nearly all of the fossil planorbids of America and Europe have been described as 'Planorhis.' With the greatest of care it is possible to place some of these species in their correct genera as understood at the present time. Some forms, however, can only be tentatively i^laced, basing the decision on the similarity of the fossil species to some known living species of which the anatomy is known. Even among modern species tliis method is fraught with danger because of similar resemblances of the shells of several genera, as in Planorbula and Tropicorbis, where some species of the latter genus have internal lamellae in the aperture similar to species of the genus Planorbula. The two genera are far ai^art anatomically. Among American fossils the following genera are known to be repre- sented by several species and races: Tropicorbis, 1 species; Paraplanorbis, 1 species; Platytapkius, 2 species; Gyraulus, 6 species; Helisonia, 8 species; Carinifex, 2 species; Vorticijex, 8 species; Perrinilla, 2 species; Parapholyx, 2 species; Pompholopsis, 1 species; Menetus, 5 species; Planorbifex, 1 sjjecies. Many of the species now known as Planorbis may later be placed in more appropriate genera. It is proposed in Part II of this work to review criti- cally all of the American fossil Planorbidae, including several from the West Indies and Central America, and to endeavor to place each species in its correct genus.* The geographical distribution of the extinct species of the family Pla- norbidae is not very different from that of the recent species of the family. Fossil species of the family have been recorded from Europe, Asia, Africa, Australia, some of the islands of the Pacific Ocean, North and South America, and the islands of the West Indies. B. GEOGRAPHICAL DISTRIBUTION Like the Lymnaeidae, the Planorbidae are world-wide in their geographic distribution. There is scarcely a known region in which some of the pla- norbid snails do not live. The distribution by genera, however, is more or less limited. Typical Planorbis and Planorbarius are mostly confined to Europe and western Asia, wdth possibly some forms of circum-Mediter- ranean distribution. Helisoma is wholly American but is known from both North and South America and from some of the West Indies. A fossil species has been reported from northeast Siberia (Lindholm, 1933). This genus is numerous in North America, principally the northern part of the United States and Canada. Planorbula is found only in eastern North America from Alabama northward. Carinifex and Parapholyx are west American in distribution. Menetus is American and does not extend south of the United States. A small group of Helisoma (Seminolina) oc- curs only in the peninsula of Florida. *As explained elsewhere, Mr. Baker's death prevented him from completing Part II of this monograph. Distribution in Time and Space 39 Ai(.str(dorbi.s is known from South America and the West Indies but is not found north of the Isthmus of Panama. Tropicorbis occurs in South and Central America, in Mexico, the West Indies, and in the southern part of the United States bordering the Gulf of Mexico. Curiously enough, a closely related group, known as Afroplanorbis, is found in northern and central Africa and resembles Tropicorbis so closely, in both shell and anatomy, that it is a question whether the two groups are not identical generically. Anisus is mostly European and Asiatic. Segmentina is typi- cally European, west Asian, and north African. Several groups related to Segmentina, as Polypylis, Helicorbis, Pingiella, and Intha, are confined to eastern Asia and some of the Pacific islands. Taphius occurs only in Central America and in northern South America. Gyraulus is the most widely distributed of any of the genera of Planorbidae, being known from North America, Europe, Asia, Africa, and some of the islands of the Pacific as w-ell as from the West Indies. It is typically a northern group (palaearctic) but a few species extend southward into the tropical regions. The present study of the distribution of the members of the family Planorbidae shows conclusively the value of the anatomy in the classi- fication of the species. It is of interest to note that in considering the distribution of the genera, details of the anatomy have been the only means by which the different groupings could be made with certainty. Hence our knowledge of distribution has become more definite and better understood than was possible when shell characters were given chief taxo- nomic value. The shell alone is not sufficient to distinguish groups because there are parallels in growth tendency which render shells of widely sepa- rated genera confusingly similar in appearance. Instances of this are found in the species of Tropicorbis and Planorbida, Aiistralorbis and Helisonia, Segmentina and Polypylis, etc. Dispersal of Species The presence of species of mollusks in isolated places has been somewhat of a puzzle to many zoologists. How, for example, are ponds without inlet or outlet and more or less widely separated, populated by one or more species of planorbids or other fresh-water species? In what manner have the same species of Tropicorbis, Australorbis, or Drepanotrema found their way to so many of the islands of the West Indies, isolated by large and deep areas of salt water? Examining the distribution of Aiistralorbis, for example, we find it occurring in eastern and northern South America and also in many of the groups of islands — the Lesser Antilles, the Greater Antilles, Puerto Rico, and Jamaica. Some species of Tropicorbis have the same distribution. Natural dispersal by migration is out of the question. Driftwood might answer for land snails (at least to a limited degree) but not for fresh- water forms. A former connection with South America occurred too remotely to answer satisfactorily the question. When we examine the migration routes of the migrating birds, especially the wading birds and ducks, we are struck by the similarity of the geographic routes of the birds with the geographic distribution of the snails. One route is from Venezuela, South America, through the Caribbean and West Indian islands as follows: Trinidad, Grenada, St. Vincent, St. Lucia, Martinique, Dominica, Marie 40 The MoUuscan Family Planorbidae Galente, Antigua, St. Christopher, St. Thomas, Puerto Rico, Haiti, Ja- maica, and Cuba. The three genera Australorbis, Tropicorbis, and Dre- panotrema inhabit most of the islands mentioned. Another route is from Venezuela northward up the eastern coast of Panama, close to Costa Rica, Nicaragua, Honduras, Guatemala, eastern Mexico to the gulf coast of the United States. The genus Tropicorbis has this distribution and many of its species are widely distributed. Some migrant birds pass up the west coast of Central America and ]\Iexico. It is the writer's belief that the populating of many if not all of the islands of the West Indies with planorbid and other fresh-water mollusks has been brought about through the agency of migrating birds. They stop at these islands to feed and rest, the snails become attached to the feet or other parts of the bodies of the birds, to be liberated when the birds make other stops. Young snails have been found attached to the feet of many birds. In the case of the Basommatophorous mollusks a single snail in- troduced into a pond would be sufficient to insure population since self- fertilization is easily accomplished. By this means in a few years a body of water would be a prolific habitat for the species. Aquatic insects, especially beetles, would perform the same service, especially in populating closely associated ponds or streanis. Young snails have been found attached to the wings (elytra) of beetles. Natural migration doubtless takes place in connected streams and other bodies of water and will account for the dispersal of related species within the drainage of a water system. Floods often carry species of snails over natural divides. In the distribution and dispersal of the Mollusca, all agencies must be taken into account. The scarcity of records of snails on the bodies of migrating birds is primarily due to the fact that those who kill the birds, sportsmen and hunters, pay no attention to what may be at- tached to the feet of their victims. Ornithologists, too, do not carefully ex- amine the bodies of the specimens and the snails fall off or are brushed off during the preparation of the skin for the cabinet. Careful examination of the bodies of birds would doubtless provide many valuable evidences for avian dispersal of fresh-water and other mollusks. V. HISTORICAL SKETCH OF CLASSIFICATIONS IX THE EARLY VOLU:\IES on the IMollusca, the planorbids, as well as other genera, were largely classified by the shells and were placed in families with wide limits as to the genera involved. Thus in 1851- 1856, in S. P. Woodward's Manual of the Mollusca, nearly all of the genera of fresh-water pulmonates — Limnaea, Chilina, Physa, Planorbis, and Ancylus — appear in the family Limnaeidae. In A History of British Mollusca, by Forbes and Hanley, in 1853 (volume iv) the fresh-water pulmonates of the genera Limnaea, Planorbis, Physa, and Ancylus are all placed in the family Limnaeidae. AV. G. Binney, in 1865, published a work on The Land and Fresh-Water Shells of North America, in which the fresh-water pulmonates are all placed in the family Limnaeidae with Limnaeinae, Planorbinae, and Ancy- linae as subfamilies, Physa being included in the subfamily Linmaeinae. Li 1870, W. H. Dall proposed a classification in which four subfamilies were recognized: Limnaeinae, Planorbinae, Camptocercinae, and Pom- pholiginae. In 1872, George W. Tryon, Jr., in a Monograph of the Fresh- icater Univalve Mollusca of the United States, placed all groups under the family Physidae, but separated the principal groups as subfamilies: Limnaeinae, Pompholiginae, ^legasystrophinae, Planorbinae, and An- cylinae. In this grouping he was following Haldeman ( 1842-1844) who |)laced Planorbis and other groups in the family Physidae. Paul Fischer, in the Manuel de Conchyliologic (1883), listed most of the fresh-water pulmonates under the family Limnaeidae, within which he recognized Ancylinae, Limnaeinae, and Planorbinae as subfamilies. Physa he relegated to a separate family. Tryon, a year later (1884), in the third volume of his Structural and Systematic Conchology, placed all of the fresh-water pulmonates under the family Limnaeidae with subfamilies Limnaeinae (including Physa, Aplexa, Bulinus, etc.), Pompholiginae, Planorbinae, and Ancylinae. A. H. Cooke, in 1895, evidently following Paul Fischer, separated Physidae as a family but places the subfamilies Limnaeinae, Planorbinae, and Ancylinae in the Limnaeidae. F. C. Baker in 1902 and Dall in 1905 separated Physa and Aplexa to form the family Physidae but placed Limnaea [Lymnaea) , Planorbis, and allied genera in the family Limnaeidae. Ancylus was made a separate family, Ancylidae, by Baker. In 1902, Westerlund placed all of the Basommatophorous mollusks in the family Limnaeidae with four subfamilies, Limnaeinae, Physinae, Planorbinae, and Ancylinae. Dybowski (1903) proposed a classification of tlie Basommatophora in which six families were recognized, Limnaeidae, Limnophysidae, Amphipeplidae, Planorbidae, Ancylidae, and Physidae. Bryant "Walker ( 1918) in his 'Synopsis' recognized four families, Lym- naeidae, Planorbidae, Physidae, and Ancylidae. From 1920 onward, most of the important monographs and lists have accepted the four-family division of the Basommatophora, Lymnaeidae. Planorbidae, Physidae, and Ancylidae (Germain. 1921-23; Kennard and 41 42 The MoUuscan Family Planorbidae Woodward, 1926; Pilsbry and Bequaert, 1927; F. C. Baker, 1928; Haas, 1929; Lindholm, 1926; thiele, 1931; and others). Germain (1931), in his Mollusks of France, recognized five families, the four previously alluded to and Bulinidae, the groups of which were thought to constitute a family. Many other works might be listed, especially by European writers, as Lindholm, Westerlund, Clessin, Dybowski, Odhner, Pallery, Preston, Soos, and others. The most important of these are listed in the synonymy under the different genera. The large monographs, such as Clessin ( 1886) and Sowerby (Reeve, 1872), do not help much in family distinctions and the lesser faunal lists of both continents, of which there are many, simply copy the classification as published in some of the works mentioned above. In the matter of generic distinctions among the planorbids there is little of note in the earlier works. In 1884, Tryon listed most of the group names as subgenera of Planorbis, recognizing Segmentina as a distinct genus. Pompholyx, Carinifex, and Choanomphalus are listed as genera with some subgenera, mostly fossil groups. In 1905, Dall considered all groups but Segmenti7Ui as subgenera of Planorbis. Germain, 1921, followed Dall. Kennard and Woodward (1926) did likewise. In 1926, F. C. Baker recog- nized the groups Helisoma, Planorbula, Menetus, and Gyraulus as being of generic rank and in 1928 fully described these groups, giving anatomical reasons for their distinction. Among European works, Lindholm in 1926 recognized as of generic rank Planorbis, Tropidiscus, Spiralina, Anisus, Gyraulus, Bathyomphalus, Armiger, Hippeutis, and Segmentina, a great step in advancement over previous works as regards classification. Thiele in his Handbuch (1931) was too conservative, listing all groups as sections under the genera Planorbis and Anisus. Mori (1938) in his classification of Japanese Planorbidae followed Thiele. It is to be observed, however, that all of these genera or subgenera as treated by early authors, were diagnosed from shell characters for the most part. In a review of the classifications of the Basommatophorous grouji the change in number of families and genera recognized is noteworthy. From one family in 1870 (Limnaeidae or Physidae) this grouping has grown to five at the present time, indicating a tendency to recognize smaller group differences and also indicating advance in knowledge concerning these groups. Many generic and subgeneric names have been proposed during the past ninety or one hundred years but these were founded almost wholly on shell characteristics. No such analytical studies as those on the land mollusks by H. A. Pilsbrv and bv H. B. Baker were made until after the year 1920. Studies of the anatomy of the Planorbidae began in Europe many years ago but were confined to only a few species. ]\Iost of the early papers or works on anatomy simply gave as illustration a familiar example, as, for example, Planorbis corneus and Limnaea stagnalis figured by Moquin- Tandon in 1855. Baudelot (1863) published good figures of the genitalia and other organs of Planorbis corneus {= Planorbarius) . In 1867, Ficinus, an almost forgotten WTiter, published an article on the penis of Planorbidae in which he divided the European species of Planorbis into two groups, (1) with a penial stylet, including Planorbis vortex, leucostoma, spirorbis, albus, and contortus, and (2) without a stylet, including Planorbis corneus, nitidus, and Jontanus. He erected the genus Appendicularia for Planorbis Historical SkelcJ) oj Classifications 43 7iiti(lu.s and F. fontdnus because of the presence of the flagella on the penis. This is, as far as known to the writer, the first attempt to chissify the Planorbidae by reference to details of the anatomy. In 1891, Buchner pubHshed the first comprehensive account of the genitalia of the family Planorbidae. He divided the male organ into four types, (1) corneus with a small penis, (2) nitidus and cotnplanatus with flagella and sperm outlet at the side, (3) marginatus and carinatus with sperm outlet in the center, and (4) contortus, vortex, rotundatus, and albus with a stylet. He did not distinguish the peculiar gland of corneus from the penis. The difference between the prostate diverticula of Planorbis corneus and the smaller species, vortex, carinatus, nitidus, etc., w'as espe- cially mentioned but no reference was made of the presence of a separate prostate duct. There was a good account of the excretory organ (kidney). Simroth's account (1912) of the genitalia of the Planorbidae was based on Buchner's work and added nothing to our knowledge of the antomy of the group. In 1917, L. Soos published a paper on the anatomy of the Hungarian Planorbidae, giving figures of the genitalia of Planorbis corneus, Tropidis- cus planorbis, Segmentina nitida, Bathyomphalus contortus, Gyrorbis spirorbis, and Gyraulus albus. The radulae and the digestive system were also considered. This is the best work on the anatomy of the Planorbidae which had appeared up to this time. During the decade from 1921 to 1930, several notable papers appeared on the anatomy of the family. Annandale (1922) and Annandale and Prashad (1919-1921) added to our knowledge of the anatomy of the Indian Planorbidae. In 1923, Rao published an exhaustive treatise on the anatomy of Annandale's new genus Indoplanorbis. Connolly (1925) figured the genitalia and radula of Planorbis pfeiffen which indicated that it was related to the West Indian genus Tropicorbis. F. C. Baker, in 1926, pub- lished notes on the genitalia, jaws, and radulae of certain American Planorbidae and in 1928 (AIolI. of Wis., I, pp. 306-387) presented descrip- tions and figures of the genitalia, jaws, and radulae of the species of Pla- norbidae inhabiting the Middle West. The subfamily Helisominae (Heli- somatinae) was proposed as new on page 309 of that work. The classifica- tion of the genitalia is based on that of Buchner with the addition of two types, one new and one following Annandale. In 1929, Odhner published an account of the Alollusca of the Tiikerns in which the genera were separated by characteristics of the genitalia, radulae, and other anatomical features. On page 22 a key appeared in which the groups were briefly diagnosed from the anatomical standi)oint. This was the most modern treatment which the family had received and the key is the first attempt to separate the genera by the use of anatomical differences. During the decade 1931 to 1940, several critical papers appeared on the anatomy of the Planorbidae, adding greatly to our knowledge and clearing up many doubtful jioints in the classification based on the anato- my. In 1931, Germain issued his work on the land and fresh-water mol- lusks of France in which outline figures of the genitalia, and some of the radulae, were given. No attempt was made, however, to base a classifica- tion on the anatomical data. Also in 1931, appeared F. C. Baker's paper 44 The Molluscan Family Planorbidae on the classification of the larger planorbes of Europe and America, in which Planorbis corneus and the American Helisoma species were discussed and the genitalia and radulae figured. The peculiar penial gland of the genus Helisoma was discussed at length. The same author, in 1933, made a study of the peculiar genitalia of Indoplanorbis exustus of India adding some features to the previous paper by Rao. Later, the same author pub- lished short papers placing certain disputed species in their proper generic position, based on their anatomy. Thus, in 1935, Planorbis wmbilicatellus, long thought to be a Gyraulus, was shown to be a member of the genus Menetus and a new subgenus was proposed for Menetus exacuous (Promenetus) . In 1936, Planorbis obstructus was shown to belong in the genus Tropicorbis and the true relationship of Parapholyx was indicated. In 1935, A. Soos published a paper on the Planorbidae of Hungary which included good figures of the genitalia of the species inhabiting that country. In 1934, a paper from the pen of H. A. Pilsbry discussed the planorbid fauna of Florida, their genitalia were figured, and a new name {Sem.inolina) was proposed for the group which is not found outside of the Florida peninsula. The classification of other groups, Tropicorbis, Menetus, Carinifex, and Parapholyx was .discussed and a new genus Australorbis was proposed for the large snails inhabiting South America and the West Indies. The European genus Anisus was ably discussed. A new subfamily, Planorbulinae, was established. Characteristic keys to the genera of American Planorbidae were given, based on anatomical features. It is not overstating to say that this paper is the most comprehensive account of the family Planorbidae from a modern standpoint that has yet appeared. From the foregoing summary it is plainly obvious that a detailed study of the classification of the family Planorbidae, based on anatomical in- formation, comparable to the methods used by Pilsbry on the land mol- lusks, is still to be prepared. An attempt to supply this deficiency is the purpose of the present work. It is believed that a foundation has been laid upon which to build a natural classification of the fanfily Planorbidae. VI. A NEW CLASSIFICATION OF THE FAMILY PLANORBIDAE GENERAL DISCUSSION DURIXG THE PAST FIFTY YEARS, the classification of the land shells (Stylommatophora) , under the able leadership of Dr. Henry A. Pilsbry, of the Academy of Natural Sciences of Philadelphia, has been brought to a high degree of accuracy and completeness. This has been accomplished by the study of anatomical details of the genera and species, bringing together groups which are allied by features of the natural organization of the animal. While the shell has helped in many cases it has been the internal features, chiefiy the genitalia, that have given criteria for generic and higher distinctions. The results obtained by these studies have been accepted by nearly all malacologists and conchologists. No such comparable work has been done on the fresh-water pulmonates (Basommatophora), and the few attempts to apply anatomical criteria for generic distinctions, as used in the Pulmonata, have met with more or less criticism. It is obvious, however, that only by the careful study of the internal organs of the animal can a natural classification be secured. This was attempted by the writer for the Lymnaeidae in 1911 and some grati- f^'ing results were obtained. The family Planorbidae offers better charac- teristics for purposes of classification than does the Lymnaeidae, there being a greater diversity of structural features among the different genera. For the data in the present work a large number of species of the family Planorbidae, from different parts of the world, were dissected. These repre- sent a majority of the generic groups so far published, in addition to several new genera. As in the study of the land mollusks, the genitalia have been of the greatest assistance. Few new groups were necessary because those already published, of which there were many, were adequate to represent the different anatomical features involved. In the new classification here presented, great stress is laid on the differences in the male genitalia, the size of the preputium and vergic sac; the characteristics of the prostate diverticula and the prostate duct; the presence or absence of a stylet on the verge; flagella present or absent on the vergic sac; a penial gland in the preputium and whether this has an internal or an external duct or none at all; the opening of the sperm canal in the verge, whether at the end or on the side; the number of retractor muscles of the penial complex; and the nature of the ovotestis, whether the diverticula are in a double series or are multiple. Other anatomical features also aid in classification, as the shape of the kidney, whether it is smooth or has a ridge; the condition of the jaws, whether simple or fragmented; the form of the radula teeth; the shape of the stomach and the turns of the intestine from stomach to anus. The pseudobranch also offers some criteria although this organ is fairly uniform in the family. It does effectively separate the Planorbidae from the Bu- linidae, the pseudobranchs of the two groups being markedly different. For generic purposes, the shell offers less assistance than the organs of the animal, although the shell sometimes presents characteristics of generic importance. 45 46 The Molluscan Family Planorbidae It has been possible to recognize four subfamilies of the family Planor- bidae based on fundamental anatomical differences, and all of the genera, as far as they have been examined, readily fit into this subfamily classi- fication. A few groups, as Taphius, Biomphalaria, Platytaphius, and Tro- chorbis, are still unknown anatomically, but it is believed that when examined they will be found to fit into this classification. Many species of the family still remain of wliich the animal characteristics are unknown and it is possible that new genera or subgenera will need to be made for their inclusion. It is confidently believed that the classification herein presented will form a reliable foundation on which to build future knowl- edge which may be obtained concerning this interesting family. ANATOMICAL KEYS TO GROUPS* Key to Subfamilies la. Prostate a single row of diverticula usually placed on a separate prostate duct. . .2 b. Prostate with multiple diverticula usually placed on the sperm duct 3 2a. Vergic sac with flagella Segmentininae (see p. 47) . b. Vergic sac without flagella Planorbinae (see p. 46). 3a. Prostate forming a fan-shaped pattern in cross section, penial gland duct on outside of preputium, ovotestis consisting of several diverticula arranged fanwise Helisomatinae (see p. 47). b. Prostate forming a finger-shaped pattern with few diverticula, penial gland duct inside preputium, ovotestis with paired diverticula. .. .Planorbulinae (see p. 48). Key to Genera of Planorl)inac+ la. Prostate diverticula on separate duct, simple, unbranched at end 2 b. Prostate diverticula not on separate duct, branched at end Aiifitralorhift (see i). 90). 2a. Verge with .stylet, outlet of sperm canal at side 3 b. Verge without stylet, outlet of sperm canal at end 6 3a. Shell with many closely coiled whorls not increasing greatly in diameter 4 b. Shell with few loosely coiled whorls rapidly increasing in diameter 5 4a. Left side of shell flat without central depression Anisus s.s. (see p. 57). b. Left side of shell with deejily excavated depression (Subgenus) Bathijomphnlus (see p. 62). 5a. Left side of shell with rounded whorls on a plane surface. . .Gi/m»/i<.s s.s. (see p. 66). b. Left side of shell with whorls depressed as though reamed out (Subgenus) Torquis (see p. 72) . 6a. Vergic sac le.ss than one-fourth length of preputium Planorhis (see p. 51). b. Vergic sac longer than preputium 7 7a. Vergic sac about as long as preputium, shell 5 mm. or more in diameter, not costate 8 b. "\>rgic sac much longer than preputium. shell 3 mm. or less in diameter, usually costate Anniger (see p. 75) . 8a. Species inhabiting Africa Afroplanorbis (see p. 86) . b. Species inhabiting America Tropicorbis s.s. (see p. 85) 9 *In using this type of alternative key the options are always arranged in couplets, the contrasting conditions being arranged as 'a' and 'b' under the same numeral. The reader always starts with la. If the description under la fits the specimen or concept under consideration, the numeral at the end of that line indicates the next couplet to be tried (except in those instances where la leads directly to an identification). If the .statement under la does not fit, the alternative under lb should, and so on through tile key until a group name is reached at the end of one of the options. This form of continuous and consecutive key is less confusing than the type in which descriptions to be compared are widely separated from each other and does not offer the technical diflScuIties of composition inherent in the indented or step form of key. — H.J.^'-C. tSome subgenera which have distinctive morphological characters are included in this key and in all succeeding keys to genera. A Xew Classification of the Family Planorbidae 47 Oil. Shell with closely coiled whorls slowly increasing in diameter, orbicular 10 b. Shell with loosely coiled whorls rapidly increasing in diameter (Subgenus) Latcorhis (see p. 85). 10a. Ajierture without internal lamellae at any stage of growth Tropicurhi.s s.s. (see p. 85) . b. Aperture with internal lamellae during a i)art of the shells growth (Subgenus) Ohstrurtio (see p. 85). Key to Genera of Segnientininae* la. Genitalia with penial gland in preputium 2 b. Genitalia without penial gland in preputium 5 2a. An external penial gland duct on preputitmi 3 b. Without penial gland duct on preputium 4 3a. External duct very short, half as long as preputium; penial gland a simple cup attached 'to wall of preputium; flagella more than twice as long as vergic .sic, sausage-shaped, attached to short ducts Intha (see p. 112). b. External duct about four times as long as preinitium; penial gland sac-like, bifurcated; flagella consisting of small cylindrical sacs attached to very long ducts Pingiella (see p. 109). 4a. PreiHitiinn narrow, club-shaped; vergic sac longer than preputium; verge slender with vergic appendage at end Segmentina (see p. 96). b. Preputium wide, pear-shaped; vergic sac shorter than preputium; verge wide at upper part, without penial appendage Hippeutis (see p. 100). 5a. Flagellum long and narrow; vergic sac and preputium of about the same length ; shell more than 5 mm. in diameter 6 b. Flagellum wide and short; vergic sac about twice as long as preputium; shell very small, 1.5 mm. in diameter Acrorbis (see p. 121). 6a. Flagellum as long as penial complex, swollen or club-.?haped at sununit Polypylis (see p. 104) . b. Flagellum shorter than penial complex, not swollen at summit, often bifid at the end Drepanotrema (see p. 114) 7 7a. Shell with rounded pcrijihery Drepanotrema s.s. (see p. 118). b. Shell with angulated or carinated i>erii)hery. . (Subgenus) Fo.<>!^ulorbis (see !>. 118). Key to Genera of Helisomatinae+ la. Prejiutium with i)enial gland but without penial duct ... .PlnnorbariJi^ (.see p. 166). b. Preputium with external penial gland duct 2 2a. Penial complex with one retractor muscle 3 b. Penial complex with two retractor muscles 6 3a. Penial complex with but little constriction between vergic sac and preputium; Ijenial gland duct about half as long as preinitium. . .Hclisoma s.s. (see p. 124) . . .4 b. Penial complex with notable constriction between vergic sac and preputium; penial gland duct as long as the jn-eputium. .. (Subgenus) Scminolina (seep. 129). 4a. Penial complex with vergic sac and preputium equal in length, the preputium much wider than the vergic sac; jjenial gland duct several times as long as preputium, in a coil between vergic sac and preputium 5 b. Penial complex with vergic sac shorter than the preputium. which is elongate; penial gland short and thick, not longer than preputiimi 6 5a. Shell with simple aperture, not campanulate. .. (Subgenus) Picrostnna (see p. 134). b. Shell with campanulate or bell-shaped aperture (Subgenus) Planorbella (seep. 150). 6a. Penial duct on outside of preputium very short, slender, placed between vergic sac and preputium; penial gland an elongated cup with wide a]ierture Carinifex (see p. 154). b. Penial duct twice as long as in 6a, thick, wide, extending from upper part of ju'eputium to vergic sac; penial gland pijie-shaped, with a long "stem" at- tached to a short "bowl" Parapholijx (see p. 161). *One subgenus is included among the groups differentiated in tliis key. tSeveral subgenera are also differentiated in this key. 48 The Molluscan Family Planorhidae Key to Genera of Planorbulinae* la. Penial gland sausage-shaped with round, closed duct 2 b. Penial gland flattened, ovate, with open, channel-like duct 3 2a. Penial duct very short leading from gland direct to muscular collar or diaphragm Menet us s.s. (see p. 183) . b. Penial duct long, extending up the side of the preputium to the muscular collar or diaphragm (Subgenus) Micromenetus (see p. 187). 3a. Penial gland connected with muscular collar by an open duct as long as the gland, lying above a single diagonal projection of the left pilaster; seminal vesicle composed of many diverticula forming a mulberry appearance on the surface Flanorbuln s.s. (.sec \\. 173). b. Penial gland connected with muscular collar by an open slit in the muscular wall of the preputium, the two pilasters sending branches from both sides to this slit; seminal vesicle consisting of many short diverticula stretched along a large part of the ovisperm duct Frotnenetus (see p. 178). SYSTEMATIC LIST OF GENERA AND SUBGENERA RECOGNIZED IN THIS WORK In the following list the genera and subgenera are arranged in the sequence which appears most in accord with their structural features. Several groups are unknown anatomically and these are marked by an asterisk. They are placed in the subfamilies and near the genera with which they appear to be affiliated. The fossil species, it is obvious, can never be known anatomi- cally and these are placed near those genera which they most nearly re- semble. The fossil groups are marked by a dagger. Two groups of uncertain affinities, one recent and one fossil, are placed at the end of the family sequence. The type species is indicated following the name of each genus or subgenus. Family PLANORBIDAE H. and A. Adams, 1855 Subfamily Planorbinae Pilsln-y, 1934 Genus Planorbis Geoffrov, 1767 Helix planorbis Linn. Genus Anisus Studer, 1820 (Gray, 1847) Subgenus Anisus SS Helix spirorbis Linn. Subgenus Costorbis Lindholm,t 1926 Planorbis strauchianus Clessin Subgenus Bathyomphalus (Ag.) Charp., 1837. .Helix contorta Linn. Genus Odontogyrorbis L6renthey,t 1906 Planorbis krambergeri Halavdts Genus Gyraulus (Ag.) Charp., 1837 Subgenus Gyraulus SS Planorbis albiis Miiller Subgenus Torquis Dall, 1905 Planorbis parvus Say Genus Armiger Hartmann, 1840 Nautilus crista Linn. Genus Taphius H. and A. Adams, 1855 Planorbis andecolus Orb. Genus Tropicorbis Pilsbry and Brown, 1914 Subgenus Tropicorbis" SS P. liebmanni T>nn\s.Qr = orbiculus Morelet Subgenus Obstructio Haas, 1939 Planorbis janeirensis Clessin Subgenus Lateorbis F. C. Baker (New) Planorbis pallidus C. B. Adams Genus Afroplanorbis Thiele, 1931 Planorbis sudanicus Martens Genus Syrioplanorbis F. C. Baker, f new name for Heterodfscus West., preoccupied Planorbis libanicus West. Genus Biomphalaria Preston, f 1910 Biomphalaria smithi Preston Genus Australorbis Pilsbry, 1934 Planorbis glabratus Say Genus Anisopsis Sandberger,t 1875 Planorbis calculus Sandberger *One subgenus is included in this key. tThe anatomy is not known for any member of this group. JA group represented by fossils only. A New Classification of the Family Planorbidae 49 Siil)family SEGMENTININAE F. C. Baker (New) Genus Segmontina Fleming, 1817 Planorbis nitidus Mtiller Genus Hippeutis (Ag.) Charj)., 1837 Planorbis complanatus Drap. Genus Polypylis Pilsi)rv, 1906 Planorhis largillurli, Phil. Genus Helicorbis Benson, f 1855 Planorbis umbilicalis Benson Genus Trochorbis Benson,! 1855 Trochorbis trochoid iics Benson Genus Pingiella F. C. Baker (New) Pyramidula pi'ipinoi-^lx Ping and Yen Genus Intha Annandale, 1922 Intha capitis Annandale Genus Drepanotrema P^ischer and Crosse, 1880 Subgenus Drepanotrema SS Planorbis anatinum Orb. {=yzabalensis C. and F.). Subgenus Fossulorbis Pilsl)rv, 1934 Planorbis cnltratus Orb. Genus l'arai)l:in()rl)is Ilanna,! 1922 Planorbis condoni Hanna Genus Platytaphius Pilsl)ry,t 1924 Planorbis hcteroplearus P. and V. Genus Acrorl^is Odhner, 1937 Acrorbis petricola Odhner Subfamily HELISOMATINAE F. C. Baker, 1928 Genus Helisoma Swainson, 1840 Subgenus Helisoma SS Planorbis anceps Menke { = bicarinatus Sowb.) Subgenus Seminolina Pilsl^ry, 1934 Physa scalaris Jay Subgenus Pierosoma Dall, 1905 Planorbis trivolvis Say Subgenus Planorbella Haldeman, 1842 Planorbis campanulatus Say Genus Carinifcx W. G. Jiinney, 1863 Planorbis newberryi Lea Genus Vorticifex Meek, J 1870 Carinifex tryoni Meek Genus Perrinilla Hannibal, J 1912 Helisoma cordillerana Hannibal Geiuis Parapholyx Hanna, 1922 Pomplinhjx effiisa Lea Genus Pompholopsis Call,! 1888 Pontjiholap-sis irhitei Call Genus Planorbarius Froriep, 1806 Hdix contra Linn. Subfamily PLANORBULINAE Pilsbry, 1934 Genus Planorbula Haldeman, 1840 Subgenus Planorbula SS Planorbis armigerus Say Sul:)genus Haldemanina Dall, 1905 Planorbis icheatleyi Lea Genus Promenetus F. C. Baker, 1935 Planorbis exacuous Say Genus Menetus H. and A. Adams, 1855 Subgenus Menetus SS Planorbis opercularis Gould Subgenus Mieromenetus F. C. Baker (New) . . . Planorbis dilatatus Gould Genus Planorbifex Pilsbry, J 1934 Planorbis vanvlecki Arnold Groups of Uncertain Affinities Genus Choanomphalus Gerstfeldt,t 1859 Choanomphalus maacki Gerstfeldt Genus Poecilospira Morch,! 1853 Valvata multiformis Zeiten. tThe anatomy is not known for any member of this group. ♦ A group represented by fossils only. VII. SYSTEMATIC ACCOUNT OF THE SUB- FAMILIES, GENERA, AND SUBGENERA RECENT AND FOSSIL PLANORBIDAE, together with the Physidae and Bulinidae, are animals with spiral shells; the genitalia and the respiratory and excretory organs are on the left side. The shell of Planorbidae is typically sinistral in some groups (Helisoma) and pseudodextral or iiltra- dextral in many groups. The shell is carried almost vertically in the typi- cally sinistral groups but leans toward the left in other groups, principally the smaller forms. In these groups the spire is beneath and the umbilicus is above, these being respectively the right and left sides of the shell. The central tooth of the radula is always bicuspid. In Physa it is multicuspid. The chief feature separating the Planorbidae from the other members of the Limnophila is the presence of an accessory breathing organ, the pseudobranch, which takes over the office of a gill when the animal is sub- merged and can not obtain free air. The flattened, 'planorboid' shell is, of course, another distinctive feature of the family. The groui)s of genera related to Bulinm and Physopsis have in the past been included in the family Planorbidae because of the similarity of the radulae and the presence of a pseudobranch. But this organ in Bulinus is different from the pseudobranch in Planorbidae, being in the form of folds or ridges while in the Planorbidae it is smooth and leaf-like. There are also differences in the genitalia, principally in the penial complex. These differ- ences suggest that Bulinus, Physopsis, and other related groups should form a separate family Bulinidae. This has been recognized by Germain in his mollusks of France (1931) and by Larambergue in a recent publica- tion (1939). The Indian genus Indoplanorbis has been shown by the latter author to be related to Bulinus and its place appears to be with the Bulinidae. Subfamily PLANORBINAE H. A. Pilsbry, 1934 The subfamily of H. and A. Adams is equivalent to the family Planorbidae as now recognized by systematists. In the Planorbinae the prostate diver- ticula are all simple sacs placed in a single row along the whole length of a long prostate duct which is separated from the sperm duct into which it enters. The ovotestis has the diverticula arranged in a double row. An apparent exception is found in tiie genus Australorbis where the single row of glands is placed directly on the sperm duct and the ends of the prostate diverticula are branched. The kidney is usually rounded and without a superposed ridge. Here again Australorbis is an exception, having a ridged kidney as in Helisoma. Tvpe genus Planorbis Geoff roy. There is considerable variation among the different genera grouped in Planorbinae, principally in the jaws, the radulae, and the presence of a penial stylet. These differences may be tabulated as follows: Radula with serrated marginals placed hijih up on the reflection: Planorbis, Bathyomphahis, Anisms, Gyraulus, Armiger. Radula with claw-like marginals on a long reflection: Australorbis, Tropicorbis. 50 Subfamilies, Genera, and Subgenera — Recent and Fossil 51 Radiila with interstitial cusps on laterals or marginals: Australorbis, Twpicorbis. Jaw in three pieces, a superior and two lateral jaws: Tropicorbis, Auslralorbis, Ajroplanorbis. Jaw fragmented with many plates: Planorbis, Bathyomphalus, Anisus, Gyraulus, Armig( r. ^'erge with stylet : Anisus, Bathyomphalus, Gyraulus. Verge without stylet: PUmorbis, Armiger, Tropicorbis, Ajroplanorbis, Auslralorbis. Several groups are unknown anatomically and hence their position in the system can not be definitely known until the animal has been examined. Such are Costorbis, Syrioplanorbi)^, Taphius, and Biomphalaria. The fossil group supposed to belong to this subfamily, Odontogyrorbis, can only be placed by shell resemblances and this points to the Planorbinae. ■ Genus PLAXORBIS Cleoffroy, 1767 Genotj'pe by tautonomy Helix planorbis Linn. 1767. Planorbis Geoffroy, Traite Coq., Paris, p. 12. No tj'pe designation. 1774. Planorbis Muller, (part) Verm. Terr. Hist., II, p. 152. No type designation. 1833. Anisus Fitzi.n-ger. (part) Beitr. Lande.sk. Oester. Ill, ]k 111 (Xon Dejean. 1821, Coleoptera). 1847. Spiralina H.\rtm.\nx, Herrmannsen, Ind. Gen. Mai.. 11, V- 286. As synonym of Planorbis. 1850. Tropidiscus Steix, Schn. u. Muscheln Berlins, p. 76. As subgenus. Tj'pe desig- nated by Clessin, 1886 — Planorbis marginatus Drap. 1852. Anisus [Fitzixger] Herrm.\xxsex, Ind. Gen. Mai., Suppl. p. 9. Tjqie: Pla- norbis umbilicatus Miiller. As fixed b,v Gray, 1847. Xot Anisus Studer, 1888. 1855. GyrorbU Moq.-T\xd., (part) Hist. Xat. Moll. Terr, et Fluv. France, II, p. 428. No type cited. As genus. 1855. Omalodiscus Bexsox, Jour. Asiatic Soc. Bengal, XXIV, p. 127. T3-pe designated by Kennard and Woodward, 1924, Omalodiscus marginatus Drap. 1883. Tropidiscus Fischer, Man. Conch., p. 509. Xo type designation. As section. 1885. Tropidiscus Westerluxd, Fauna Palaearc. Reg., V, p. 64. X"o type cited. As sub- genus of Planorbis. 1886. Tropidiscus Clessix, Syst. Conch.-Cab.. XVII, p. 34. Type Planorbis marginatus Drap. As subgenus. 1898. Planorbis (Geoffroy) vox M.artexs, Biol. Centr. Amer., :Mo11.. p. 380. Xo type cited. As genus. 1902. Tropidiscus Westerluxd, Had. Jugoslav. Akad., 151, p. 120. Genotype Helix planorbis Linn. As subgenus. 1905. Placorbis DR.\p.\RX.\rD, X'at. Hi.st. Moll. France, p. 138. (vide Lindholm, Archiv. fiir Mollu.sk., 58 year. Heft 6. p. 252). 1905. Tropidiscus D.\ll, Alaska Moll., p. 85. Type Planorbis umbilicatus Muller = Planorbis complanatus Stein. 1906. Otnalodiscus D.\ll. X'autilus XIX, p. 105. Comments on nomenclatorial position but cites no type. 1917. Tropidiscus Sees. Ann. Musei X'at. Hungarici, XV, pp. 40, 141. Type Tropidiscus planorbis (Linn.). As genus. 1921. Tropidiscus Germaix'. Rec. Ind. Mus., XXI, p. 7. Type Planorbis planorbis (Linn.). As subgenus. 1923. Planorbis (of Muller 1774) Wexz, Fossil. Cat., Part, 22, p. 1523. Genotype Planorbis planorbis (Linn.). As genus. 1926. Tropidiscus (of Stein) Lixdholm. Archiv. fur Mollusk., 58 year. Heft 6. p. 252. Ideogenotype Helix planorbis Linn. As genus. 1927. Planorbis Kexx.ard and Woodw.xrd, Syn. British Xon-Marine !Moll., p. 66. Tj'pe by tautonomj' Helix planorbis Linn. As genus. 52 The Molluscan Family Planorbidae 1929. Planorbis (of Miiller 1774) Haas, Trab. Mus. Cien. Nat. Barcelona, XIII, p. 379. Tj'pe evidently intended to be Planorbis phniorbis (Linn.). As genus. 1930. Planorbis H. B. Baker, Oc. Papers, Mus. Zool. Univ. Mich., No. 210, p. 42. Type b.y absolute tautonomy Helix planorbis Linn. As genus. 1931. Planorbis Germain, Moll. Terr, et Fluv. France, II, pp. 516, 521. No type desig- nation. As genus and subgenus. 1931. Tropidiscm Thiele, Handbuch, IV, Teil 2. p. 481. Type Plaiiorbis planorbis (Linn.). As subgenus. 1935. Tropidiscus Soos, Allat. Kozlem., XXXII, p. 29. Planorbis carinatus Miiller and Planorbis planorbis (Linn.) cited. As subgenus under genus Anisus. 1936. Planorbis (of Miiller 1774) R\as, Abh. Senckn. Natur. Gesell., No. 431, p. 25. Planorbis planorbis (Linn.) by absolute tautonomy. As genus. Shell (plate 77, figs. 26-28) discoidal with few whorls, regularly in- creasing in diameter; upper and lower (left and right) sides flattened; a carina encircles the body whorl on the left side; aperture small, rounded, or oval, the right side in advance of the left side. Animal. External appearance. The body is small, the foot short, rounded before and pointed behind; tentacles long and filiform; eyes sessile at the inner base of the tentacles; when removed from the shell the animal of Planorbis planorbis has a blackish or lead-colored mantle, a yellowish liver, and a pinkish ovotestis. ANATOMICAL CHARACTERISTICS PLATE 1 GENITALIA. Male Organs (fig. 1). Seminal vesicle (SV) 3.5 mm. long and 0.7 mm. wide, elongate-cylindrical, covered for the most part by small pustule-like glands. Sperm duct (SPD) very long (14 mm.) adherent to the oviduct. The prostate (PRS) is about 5 mm. long and consists of forty to forty-five diverticula placed in a single row on a long prostate duct (PD) which is separated from the sperm duct. Both sperm duct and prostate duct enter the smaller vas deferens near the vagina (fig. 1, YD, PD). The prostate diverticula are cylindrical in form and a trifle more than 0.5 mm. in length. A cross section through the prostate and oviduct shows the relationship between the sperm duct and the prostate duct (fig. 7). The vas deferens is a long (12 mm.) narrow tube (VD). The penial complex is elongated (fig. 2), the preputium (PR) is long (3 mm.), cylindrical, and the vergic sac (VS) is short (0.7 mm.) and some- what less in diameter than the preputimn. There is one long and narrow retractor muscle (R^M) attached to the vergic sac near the junction of the latter with the preputium. A group of five or more small muscles near the base of the preputium and a longer, narrow muscle attached to the upper part of the preputium have been called supporting muscles (SM) . They are not attached to the columella muscle but to the fore part of the head. The long, narrow muscle may play a part in retracting the preputium after copulation. Internally (fig. 4) the preputium has two vertical pilasters and a large number of longitudinal muscular ridges (PL). The walls of the preputium are thin but the walls of the vergic sac are thickened, especially at the summit where the vas deferens enters. The verge (V) is short and wide in repose and nearly fills the vergic sac. A section through the verge and a Subfamilies, Genera, and Subgenera — Recent and Fossil 53 part of the vas deferens shows the sperm canal to be located in the center and to have a central exit (fig. 5). The absence of a distinct muscular ring or diajihragm is noteworthy. Female Organs. The sperraatheca (S) in the specimens examined is about 1.5 mm. long and 1 mm. wide, globular or pear-shaped, and attached to the uterus by a short, narrow duct about 1 mm. long (SD). The vagina (VG) is very short (less than 0.5 mm.) and wide. The uterus (U) is as wide as the vagina and is about 5 mm. long. The nidamental gland (NG) is as long as the uterus and surrounds a large part of the oviduct (see fig. 1). It is greatly lobulated. The free oviduct (OD) is short (about 2 mm.) and about as narrow as the sperm duct. Beneath the albumen gland the sperm duct and the oviduct are joined to form the ovisperm duct (fig. 6). The albumen'gland is large (3.5 by 2 mm.) and is a mass of small sacs (AL). A small duct enters the carrefour (CF) which in turn enters the oviduct in front of the junction of that organ with the sperm duct. Hermaphrodite Organs. The ovotestis (OT) consists of many club- shaped diverticula placed in a double row (fig. 8). The ovotestis is buried in the cell-mass of the liver (fig. 9). The ovisperm duct (SO) is divided into two external parts separated by the seminal vesicle, through which it passes. One portion, about 5 mm. long, extends back of the sperm duct at its junction with the oviduct and gradually enlarges as it enters the seminal vesicle. A smaller tube, about 3 mm. in length, passes from the seminal vesicle to the ovotestis. The genitalia of Planorbis planorbis have been figured by several European conchologists. Germain's figure (1931, p. 523, fig. 533) is in general like the figures in this work, but there is lack of detail. The spermatheca is shown in a more elongated form, but this organ is subject to more or less variation. The large seminal vesicle is indicated by a swelling in the ovisperm duct. L. Soos's figure (1917, p. 41) agrees in general with that shown in this work. The prostate shows relatively the same number of diverticula. The spermatheca is shown on a long duct and the spermatheca is pear-shaped, not rounded as was observed in all specimens personally examined. Germain's figure is like Soos's in this respect. There appears to be some variation in this organ perhaps due to seasonal or sex condition. The penial complex in Soos's figure is not shown in sufficient detail, but the position of the retractor muscle indicates a short vergic sac. The seminal vesicle shows an enlargement. A. Soos's figure (1935, p. 25) appears more nearly correct, showing for the first time the separate prostate duct. The spermatheca, however, is shown of a pyriform shape and on a long duct. The figure of the related species carinatus JMiiller (p. 24) given by Soos is more like the Poland specimens of planorbis personally examined. The duct of the prostate is shown as very short while in the Poland ma- terial the free portion of this duct is much longer before entering the vas deferens. The lower portion of the female complex is shown very much longer in Soos's figure than was observed in the Poland specimens. Respiratory and Renal Systems. The pseudobranch (P, fig. 3) is leaf- shaped, flattened, about 2.5 mm. long and 2 mm. wide. The rectum (R) pierces it after bordering the columella muscle and the anus has its exit at the lower edge (A). The respiratory tube or pncumostome (PS) forms a 54 The Molluscan Family Planorbidae short V-shaped lobe to the right of the pseudobranch. It is large and can be greatly expanded. The kidney (plate 46, fig. 9) is very long and narrow (10 mm. long, 1 mm. wide), the glandular portion occupying only about one-eighth of the length. The ureter is short (1 mm. long), narrowly tubular and turns sharply to the left into the mantle cavity. A cross section of the kidney at about midway of its length shows the lumen to be flattened and widened with a vein at each end (fig. 10). There is no ridge on the lower side. The pericardium is long-oval in shape, 2.5 mm. long and 1.2 mm. wide. Digestive System. The stomach (plate 48, figs. 6, 7) is elongated and pyriform in sliape, the blind sac about as long as the stomach. The intes- tine runs directly forward and does not make a backward loop as in Helisoma and some other groups. The stomach does not show distinct divisions into crop and gizzard. The buccal sac is elongated and shortly pyriform in shape, the fore part near the mouth somewhat tubular. The radula sac is distinct and rounded. The salivary glands are much elongated, cylindrical, and joined behind. The jaw (plate 50, fig. 21) is horseshoe-shaped and is composed of many small plates, about thirty on the upper or horizontal part, the lower or cutting edges V-shaped. The radula (plate 67, fig. 7) formula is 24-1-24, 25-1-25, or 26-1-26 and the number of rows of teeth varied as follows: 175, 176, 205, and 209. The central tooth is bicuspid with a wide base of attachment, tlie cusps long and spade-shaped; lateral teeth (1-10) tricuspid, the cusps large and spade-shaped, the mesocone largest and longest, the reflection reaching nearly to the lower edge of the base of attachment. Intermediate teeth (11-13) with the reflection reaching only about half way to the lower edge of the base of attachment, with four cusps, the ectocone split into two cusps. Marginal teeth (14-20) very narrow with the reflection placed high up on the tooth, with four cusps which become subequal toward the outer margin of the radula membrane. The outer marginals are very narrow, the width being about one-fourth of the heiglit and there are four short, sub- eciual cusps. In one membrane some of the marginal teeth (20) had the entocone split into two sharp cusps. This was rare and occurred only in atyjiical rows. The central teeth varied somewhat in width in the same membrane. For example, in rows 1 to 156 the upper part of the central tooth measured 6 microns and the lower part of the base of attachment measured 12 microns in width. In rows 157 to 176 these measurements were 5 and 12 microns respectively. In most membranes the central teeth were very uniform in width. For the above anatomical data eight specimens were examined, col- lected by Mr. A. Jankowski from a pond in Swidry-Mate, 25 km. south- east of Warsaw, Poland. No parasitic worms (cercariae) were observed in any of the specimens examined. Geographical Distribution. The genus Planorbis, as herein understood, is distributed throughout Europe from Sweden southward to the Medi- terranean and from Great Britain eastward to western Russia. It is also found in northern Asia (Siberia), Asia Minor, and northern Africa. Species Considered as Valid. Although many species now assigned to other genera were originally placed in the genus Planorbis there are now SubjafNilies, Genera, and Subgenera— Recent and Fossil 55 hut relatively few sjjecies which belong in this genus as now restrieted. The best recognized of these are: Planorbis planorbis (Linn.) Planarbis atticus Bgt. Pln7iorbis carinntus Mi'iller l^lmiorbis sieversi Mouss. Planorbis aniotddi Germain Planorbis antiochianus Locard Planorbis marmoratus Michaud Geological Distribution. Oligocene to Recent time, according to Wenz. It is probable that some of the sj^ecies included in this genus by paleon- tologists really belong to other grouj)s. Remarks. The genus Planorbis is peculiar anatomically in the form of the prostate with many single diverticula and in the comparatively small size of the vergic sac as compared with the preputium. The verge, also, is very small, short; and wide, differing markedly in this respect (as far as known) from any other group of planorbes in Europe. The nature of the genitalia and the form of the shell set this group apart as a distinct genus of the family Planorbidae. For many years, the author for this genus and the species for its type have been in dispute. Some authors (Tryon 1872, 1884, Fischer 1883, Baker 1902, Binney 1865, Dall 1870, Fischer and Crosse 1879) quote Ciuettard as authority (Mem. Acad. Sci., p. 151, 1756). Other authors have cited the genus as of ■Miiller (Verm. Hist., p. 152, 1774) with Helix cornens Linn, as type (Dall 1905, Pilsbry and Bequaert 1927, Baker 1931). A few- have used Guettard 1756 and ^liiller 1774 in combination with Helix corneus as genotype (Germain 1921, 1931). Another group of authors have cited Geoffroy (Traite Coq., Paris, p. 12. 1767) with Helix planorbis Linn, as genoty])e (Kennard and Woodward, 1924, 1926). Guettard 1756 is pre-Linnean and also non-binomial and would appear to be ruled out on these accounts. Geoffroy 1767 is post-Linnean but this author was not in all cases binomial and is rejected by some students for this reason. Kennard and Woodward (1924, p. 9), however, have presented very convincing arguments in favor of retaining the Planorbis of this atithor. The Planorbis of ]\Killer (1774) is preferred by some late writers (Dall 1905, Pilsbry and Bequaert 19271, who cite the Helix corneus of Linnaeus as genotype, giving ^Vlontfort 1810 (Conch. Syst., II, p. 270) as the first author to select a genotype. However, whether Geoffroy or Miiller is selected, the genotype for both is Helix planorbis Linn., the selection of which is governed by the rules of tautonomy (see H. B. Baker, 1930). After reviewing the evidence very carefully there seems to be no valid reason why Planorbis Geoffroy, 1767, should not be used, as advocated by Kennard and Woodward (1924). The Helix corneus Linn, is the genotype of Planorbariiis Froriep, 1806. The name Tropidiscus Stein (1850) is in use bv several European authors (Germain 1921, L. Soos 1917, A. Soos 1935,'Thiele 1931) but this name is a synonym of Planorbis, having the same genotype. Helix planorbis Linn. Genus ANISUS Studer, 1820 (Gray, 1847) Type Helix spirorbis Linn, selected b}' Gra}- in 1847 1820. Anisus Studer, Natursvis. Anzeiger Allg. Schweiz. Ges. Gesammt. Xaturwiss., 3te Jahrg., Xr. 12, p. 91. 1840. Spirorbis Sw.mxson, Treat. Malac, p. 337. Tyjic Planorbis vulgaris Swain. Not Spirorbis Daudin, 1800 (Vermes). 56 The Molluscan Family Planorhidae 1840. Spiralina Hartmaxn, Erd-und Siissw.-Ga.sterop., 'Syst. Uebersicht.' Xude name. 1843. Planorbina Haldeman, Mon. Freshwater Univalve Moll., Physidae, p. 14. Type designated by Pilsbrv 1934, Planorbis spirorbis Linn. Not Plmiorbina Dall, 1905. 1847. Anisus Studer, Gray, Proc. Zool. Soc, p. 180. Tj-pe Helix spirorbis Linn. 1847. Spirorbis Herrmannsen, Ind. Gen. Mai., II, p. 492. Type Planorbis spirorbis (Linn.). 1850. Tropidiscus Stein (part). Lebend. Schneck. und Musch. Berlins, p. 76. 1855. Gijrorbis Moquix-Tandon, Moll. Ter. Fluv. France, II, pp. 423, 428. Type desig- nated bv Lindholm, 1926, Planorbis rotundatus Foiv.=^ Planorbis leucostoma Millet. "Not Gyrorbis Fitz., 1833. As genus. 1870. Anisus Fitz. Dall, An. Lye. Nat. Hist., N.Y., IX, p. 352. Type Anisus vortex (Linn.). As section of Planorbis. 1883. Gyrorbis Fischer, Man. de Conch., p. 507. Type Planorbis rotundatus Poir. As section of Planorbis. 1885. Gyrorbis Westerlund, Fauna Palaearc. Reg., Y, p. 64. No type cited. As sub- genus of Pla7iorbis. 1886. Gyrorbis Clessin, Sj'st. Conch. Cab., XVII, p. 34. Type Planorbis rotundatus Poir. As subgenus. 1897. Diplodiscus Westerlund, Act. Soc. Fauna Flora Fennica, XIII, p. 115. First species Planorbis vortex (Linn.). Not Diplodiscus Dies., 1836, Trematodes. 1899. Spiralina Hartmann, von M.^rtens, Biol. Cent. Amer., Moll., p. 395. Type desig- nated Planorbis vortex (Linn.), by Lindholm in 1922 and Kennard and Wood- ward in 1924. 1902. Diplodiscus Westerlund, Rad. Jugoslav. Akad., 151, p. 120. First species. Helix vortex Linn. As subgenus of Planorbis. 1905. Paraspira Dall, Alaska Moll., pp. 82, 86. T^-pe by original designation Planorbis rotundatus Poir. '= Planorbis leucostoma Millet. As section of Planorbis. 1909. Tr;;.s'^;Vf Honigmann, Zeitsch. f. Naturw., 81, p. 296. Type designated by Lind- holm, 1926, Playiorbis rotundatus Poir. As synonym of subgenus Anisus. 1917. Gyrorbis L. Soos, Ann. Musei Nat. Hungarici, XV, jip. 49, 143. Gyrorbis spirorbis first species (Anatomy). As genus. 1921. Diplodiscus Westerlund, Germain, Rec. Ind. Mus., XXI, \). 7. Type Planorbis vortex (Linn.). Non Dies. 1836. As subgenus. 1921. Paraspira Germain, op. cit., p. 7. Type Planorbis rotundatus Poir. As subgenus. 1922. Spiralina (Hartmann) von Martens, Lindholm, Ann. Musee Zool. L'Acad. Sci., Russia, Tome XXIII, p. 320. Type designated by Lindholm Planorbis vortex (Linn.). As subgenus. 1923. Gyrostoma Haas, Archiv. f. Molluskund., LV, pp. 43, 45. Type designated Gyrostoma rotundatum Poir. = Planorbis leucostoma Millet. Not Gyrostoma Kirby and Spence 1828, Knietniewski 1897, or Hesse 1909. 1923. Spiralina von Martens 1899, Wenz, Fossil. Cat., pars. 22, p. 1529. Genotype Spiralina vortex (Linn.). As genus. 1923. Paraspira Wenz, op. cit., p. 1530. Genotype Paraspira rotundata Poiret. As genus and subgenus. 1926. Spiralina (Hartmann MS) von Martens, Kennard and Woodward, Syn. Brit. non-marine Moll., p. 68. Type Helix vortex Linn. As subgenus. 1926. Spiralina (Hartmann MS) von Martens, 1899, Lindholm, Archiv. f. Mollusk. 58 year. Heft 6, p. 252. Ideogenotype Helix vortex Linn. As genus. 1926. Anisus (Studer, 1820) Lindholm, op. cit., p. 253. Ideogenotype Planorbis spirorbis (Linn.). As genus. 1926. Anisiis (S. Str.) Lindholm, op. cit., p. 253. Monogenotype Spirorbis vul- garise^ Planorbis vortex var. of Drap.). As subgenus. 1929. Anisxis (Studer, 1820) H\as, Trab. Mus. Cien. Nat. Barcelona, XIII, p. 281. Type evidently Planorbis spirorbis (Linn.). As genus. 1929. Spiralina (von Martens, 1899) Haas, op. cit., p. 381. Type evidently Helix vortex Linn. As genus. Subfa/inlies, Genera, and Subgenera — Recent and Fossil 57 1931. Spifdliiia (Hartiuann, von Martens), Gekmaix, Moll. Ter. Fluv. France, II, 1>. 526. Type probably intended to be Planorhis vorlex (Linn.). As subgenus. 1931. Anisus (Studer, 1820) Thh^lk, Handbuch, iv teil, p. 480. As genus. 1931. Anisus (SS) Thiele, op. cit., p. 481. IVpe Planorhis Icucostoma Millet. As sub- genus of A)iisus. 1931. Spiralinn (Hartmann) Thiele, o\i. cit., p. 481. Type Planorhis vorlex (Linn.). As subgenus of Anisus. 1934. Anisus Studer, 1820, Pilsbry, Proc. Acad. Nat. Sci., LXXXVI, p. 62. Type Helix planorhis Linn, designated by Gray in 1847. As genus. 1935. Spiralina (Hartmann) von Martens, 1899, Soos, AUat. Kozleni., XXXII, p. 29. As subgenus of genus A^iisus. 1935. Animis Studer, 1820, Soos, op. cit., p. 29. As genus. Subgenus ANISUS SS. Ty]:)e Helix spirorhis Linn. Shell (plate 77, figs. 20-22, Anisus spirorhis (Linn.), figs. 16-18, A7iisus leucostomus (Millet), fig. 19, Anisus vortex (Linn.) ) discoidal with many tightly coiled whorls very slowly increasing in diameter, all of the whorls visible on both sides of the shell; whorls rounded or with a sharp carina at the periphery; aperture small, rounded or ovate, modified in carinate species by the peripheral carina. Animal. Externally resembling that of Planorhis. ANATOMICAL CHARACTERISTICS PLATES 6-7 GENITALIA. Male Organs (plate 6, fig. 12, spirorhis; plate 7, fig. 2, leucostomus; plate 7, fig. 6, septemgijratus) . Seminal vesicle (SV) long, cylindrical, convoluted, about three times the diameter of the ovisperm duct. Sperm duct (SPD) very long and slender (5 mm. in spirorhis, 7 mm. in septemgyratus, 3 mm. in leucostomus, and 4 mm. in vortex). The prostate is long in vortex and septemgyratus and short in spirorhis and leucostomus. The number of diverticula vary correspondingly, in vortex being about sixty, in septemgyratus fifty-seven, in spirorhis about twenty, and in leucostomus over twenty. The diverticula are sac-like, cylindrical, and are placed on a duct separated from the sperm duct which joins the latter some distance above the vagina to form the vas deferens. Cross sections through the oviduct and prostate show the separation of the two ducts (plate 6, fig. 3 vortex, fig. 8 spirorhis). The prostate duct varies in length in the different species. It is about 1 mm. long in spirorhis, but only about 0.2 mm. long in vortex, septemgyratus, and leucostomus. The diver- ticula of the prostate vary in length and diameter as shown in the figures (plate 6, fig. 12; plate 7, figs. 2, 6). The vas deferens is shorter than the sperm duct by about half its length, and, as usual, is a narrow tube. The penial complex is greatly elongated in all species of the genus Anisus. It is about 3.5 mm. long in vortex, 2 mm. long in spirorhis and leucostoinus. The preputium is always shorter than the vergic sac, which may be nearly twice as long in vortex as in spirorhis (figs. 1 and 13 on plate 6). The preputium is cylindrical, usually swollen at the upper part. The vergic sac is elongated, pyriform or club-shaped, narrowing greatly in diameter where it joins the preputium. There is one long, narrow retractor nniscle and apparently no supporting muscles. 58 The Molluscan Family Plauorhidae Internally the penial complex has certain distinctive features, as shown in fig. 10 on plate 6 ispirorbis) . The preputium has two vertical ridges or pilasters. Between the preputium and the vergic sac there is a thick muscular ring which shows as a swelling on the exterior surface of the upper part of the preputium. A large papilla (PP) is suspended between the walls of the muscular ring, the walls of which are very thick. Below the large muscular swelling there is a second smaller ring which is here called the diaphragm (D). It is relatively thin and is capable of considerable contraction and expansion, which causes the hole or foramen in the middle, as viewed from above, to be small or large. Buchner shows this ring (Ringwulst) in his fig. 1 on plate 5, but it is there shown in section as almost closed and is placed below the thick papilla. In those specimens of the four species examined the ring has been widely open and the papilla has been extended below the area of the ring (plate 6, fig. 4, vortex, fig. 10, spirorbis) . The papilla is larger and somewhat differently shaped in the figures on plate 6, varying in this respect from Buchner's figure. Possibly changes due to breeding condition may be the reason for this difference. The verge is long, cylindrically pyriform in shape above and tapering rapidly below the middle of its length to form a slender tube, at the end of which is a small, horny stylet. The sperm canal turns to the side just above the stylet where it has its exit on the side of the verge (plate 6, figs. 4, 5). The stylet is sharp and needle-like, bulbous at the upper part where it is attached to the verge. There is a fine groove extending along one face of the stylet (plate 6, figs. 2, 5; plate 7, fig. 5). The verge of vortex is much narrower than that of any other species examined. With the excep- tion of the 'Ringwulst' the penial complex of the four species of the genus Anisus agrees with the description and figure of Buchner. Female Organs. The spermatheca is much elongated and cylindrical in vortex, spirorbis, and septemgijrntus with a spermathecal duct about as long as the spermatheca (plate 6, fig. 12). In leucostomus, however, the spermatheca is short and bulbous with a short, thick spermathecal duct (plate 7, fig. 2). In several specimens of septemgyratus the spermatheca was cylindrical and acutely pointed at the summit. One specimen contained a large spermatophore (plate 7, fig. 6). The spermatheca and its duct are over 1 mm. long in spirorbis, but less than a millimeter in leucostomus. The vagina (V) is very short (less than 0.3 mm.) in all species. The uterus (U) is long and cylindrical in vortex, septemgyratus, and spirorbis, but rather short and wide in leucostomus. The nidamental gland is long and cylindrical in vortex, spirorbis, and septemgyratus but large and swol- len in leucostomus. The oviduct shows the same differences, being long and cylindrical in vortex, spirorbis (3 mm. long), and septemgyratus, but is short (about 2 mm. long) and of larger diameter in leucostomus. The ovi- duct is always of greater diameter than the sperm duct (see figs. 2 and 6, plate 7, fig. 12, plate 6). The albumen gland is elongated, narrow, and somewhat arched (plate 6, fig. 9; plate 7, figs. 2, 6, AL). Hermaphrodite Organs. The ovotestis is made up of many club-shaped diverticula arranged in a double row on the ovisperm duct (i)late 6, fig. 12; plate 7, fig. 2, OT, spirorbis and leucostomus). Two diverticula of leucostomus are shown on plate 6, fig. 7. Several diverticula of vortex had ripe ova. The ovisperm duct is divided into two parts separated by the SubjaniiUes, Genera, and Subgenera — Recent and Fossil 59 yeiuinal vesicle, as in the ii'enus Planorbis. The portion between the seminal vesicle and the ovotcstis is enlarged in septemgyratus and Icucostomus (plate 7, figs. 2, 6) but is of small diameter in spirorbis and vortex. In the first two species the enlargement is of the same diameter as the seminal vesicle, of which it may be a part. The portion of the ovisperm duct be- tween the seminal vesicle and the oviduct is a long, slender, smooth tube in leucostoinus, but in vortex, septemgyratus, and spirorbis there are small pustule-like bulgings which ai)i)ear to be glandular extensions of the sem- inal vesicle. The genitalia of the four species here recorded are in the main similar to Buclmer's fig. 11, tafcl 4, which is copied by Simroth. Germain's figure of rotundatus (=leucostonius) is similar but lacks detail (1931, pp. 527, 539). The prostate is shown too long as compared with the Poland speci- mens personally examined. Soos's figure (1917, p. 50) is like those in this work, as is also the figure of vortex (p. 53). Respiratory and Renal Systems. The pseudobranch is large, narrow, and flattened in all species examined. It is pierced by the rectum which is long and narrow. The pneumostome is cylindrical and in the specimens examined is rolled into a cylindrical tube with a large cleft extending its whole length. It varies in length in the different species (plate 6, fig. 6 vortex, fig. 11 spirorbis, and plate 7, fig. 1 leucostonius) . The kidney (plate 47) is very long and narrow, the glandular portion occupying only a small part of the entire length. In spirorbis (fig. 13) it is 5 nun. long and about 0.3 mm. wide but in vortex it is 12 mm. long and over 0.3 mm. wide. The ureter is very short and is sharply bent upward into the mantle cavity. The pericardium is very short as compared with total length of the kidney. Cross sections show no evidence of a ridge. In vortex (fig. 14) the kidney is as thick as wide and the veins are placed at the base of the rounded lumen. In leucostomus (fig. 15) the kidney is wider than high with the veins lower on the lumen. In these species the kidney is somewhat triangular in shape to fit the sharp angle caused by the pe- ripheral carina of the shell. In a cross section of spirorbis (fig. 16) the kidney is seen to be very wide and much flattened with the veins near the middle of the lumen. The kidney of Anisus does not differ in any essential way from that of Phinorbis. Digestive System. The stomach, buccal sac, and general digestive sys- tem are similar to these organs in Planorbis. The jaw (plate 50, fig. 25) is similar to that of Planorbis with about twenty plates on the upper part. The side jaws are also fragmented. The radula (plate 67, fig. 6, spirorbis) formula is 15-1-15 or 16-1-16. The numbers of rows of teeth vary from 185 to 195. Central tooth with two spade-shaped cusps reaching nearly to the lower edge of the base of attach- ment. Lateral teeth (1-10) tricus]')id, about as wide as high at first but becoming narrower toward the marginal teeth. There is but one inter- mediate tooth (11), four-cuspid, with the reflection short and wide. INIarginal teeth (12-15) narrow, four-cuspid, the reflections very short and wide. The fourth cusp appears as a splitting of the ectocone. The formulae for the other species examined are as follows: sejptemgyratus 16-1-16 with 130 rows vorlex 16-1-16 with 142 rows leucostomus 16-1-16 with 130 rows 60 The Molluscan Family Plauorbidae The teeth are all very uniform in form. Anisus has fewer teeth in a row than Planorbis, the formula of which is 25-1-25, but the teeth are similar in form and number of cusps. For the anatomical information herein presented the following ma- terial has been available, all received from Mr. A. Jankowski, of Warsaw, Poland: vortex, Eight examples from stream in meadow at Jab-Tonna, 18 km. northeast of Warsaw, Poland. spirorbis, Eight specimens from a trench in Struga, 12 km. northeast of Warsaw, Poland. septemgyratus, Three examples from turfy meadow in Drewnica, 4 km. northeast of Warsaw, Poland. leucostomus, Three sj^ecimens from small ponds in Bielany Park, Warsaw, Poland. Geographical Distribution. The genus Anisus is distributed throughout Europe from Great Britain to Russia and Siberia and southward to Italy and Algeria. Thus the distribution is about the same as that of Planorbis. One species is reported from China {paravortex). This distribution may be enlarged when other si)ecies arc examined anatomically. Species Considered as Valid, The following species are understood to conform to the concept of Anisus. Ariisus spirorbis (Linn.) Anisus johanseni (Mozley) Anisus vortex (Linn.) Anisus perezi (Dupuy) Anisus septemgyratus (Ziegler) Anisus jragilis (Millet) Anisus leucostoynus (Millet) Anisus paravortex (Ping and Yen) Anisus vorticulus (Troschel) Anisus millcti (Germain) Anisus villai (Adami) Anisus charteus (Held.) Anisus ressmannianus (West.) Anisus centrogyratus (West.) Anisus compressus (Michaud) Geological Distribution. This genus begins about the middle of the Miocene period. Remarks. The group of European planorbids under the name Anisus differs from the genus Planorbis notably in the form of the penial complex (compare fig. 4, plate 1, Planorbis, with fig. 10, plate 6, Anisus). In Pla- norbis the vergic sac is only one-fourth as long as the preputium while in Anisus this organ is always longer than the preputium and the verge is long and narrow and bears a stylet at the end, which is absent in Planorbis. The presence of the muscular ring and papilla in Anisus is also another striking difference. The seminal vesicle also differs markedly in the two genera. The shell is always flattened and many-whorled but from the shell alone the two groups could scarcely be separated generically. The proper name for the group of European planorbids typified by Planorbis spirorbis, vortex, and leucostomus has been in considerable doubt. The name most commonly found in the literature, used by Germain, Lindholm, Soos, Kennard and Woodward, and others, is Spiralina, a nude name published by Hartmann in 1840. In 1899, von Martens used the name for the European Planorbis vortex and the American Planorbis cultratus and sumichrasti. The last two species are now members of the genus Drepanotrema. Thus the type of Spiralina becomes Planorbis vortex and this species was formally designated the type by Lindholm in 1922 (p. 320), and by Kennard and Woodward in 1924 (p. 68). But in 1847 Herrmannsen (Ind. Gen. Mai. II, p. 286) listed Spiralina Hartmann in the synonymy of typical Planorbis without comment or question, thus, as Subfamilies, Genera, and Subgenera — Recent and Fossil 61 H. B. Baker remarks (1930, p. 49) 'effectually clothing and simultaneously killing the name Spiralina.' Thus no subsequent use of this name is per- missible. Dall (1905) used the name Diplodisciis Westerlund and cited Planorbis vortex as type, this being the first species listed. But this name is preoccupied by Diesing in Trematodes. In 1934 (Proc. Phil. Acad. Sci., j). 62), Pilsbry revived the early name Anisus Studer, 1820 and gave some very good reasons for accepting this name for the group tyjufied by Planorbis vortex and spirorbis, accepting Gray's subsec^uent designation of Helix spirorbis Linn, as type. In this connection he remarks Gray's type designation of 'H. spirorbis' is valid for Anisus only if the identity of spirorbis Studer and spirorbis Linn, is admitted. I see no sufficient reason for doubt- ing it. A more serious question relating to Anisus is whether a generic name is valid when admitted by its author to be for a group formed by the union of two prior genera, and containing nothing else. Unfortunately Opinion 9 of the International Commission on Nomenclature is not explicit on this point, but as Anisus has been widely used it had better be retained. Other names have been proposed for this European group and would be available but for previous use in other groups. Spirorbis Swainson, Gyrorbis, Diplodiscus, Wuestia, and Gyrostoma are thus affected, as noted in the list of synonyms of Anisus. The writer agrees with Pilsbry that, since the name Anisus has had wide use in the literature it had better be retained for this group, since it was proi:)erly clothed as a genus by Gray in 1847. Anisus is used by Thiele in his Handbuch, 1931. The best interest of nomenclature is served by the use of Anisus rather than by coining a new name. Subgenus COSTORBIS Lindholm, 1926 Type by original designation Planorbis strauchianus Clessin 1926. Costorbis Lindholm, Archiv. fiir Mollusk., 58 year. Heft 6, pp. 253, 257. Mono- genot.vpe Planorbis strauchianus Clessin. As subgenus of Anisus. 193L Costorbis Thiele. Handbuch. V, Teil 2, p. 48L Type A. (C.) strauchianus Clessin. As subgenus of Anisus. Shell (plate 76, fig. 3). Differing from Anisus in being heavily trans- versely costate, the body whorl angulated above and below, the aperture ciuadrate. Animal. The group is anatomically unknown but the shape of the shell would indicate that it should be grouped with Anisus. Geographical Distribution. Russia. Species Considered as Valid. The only species definitely referable to this subgenus is A7nsus (Costorbis) strauchianus (Clessin). Remarks. It is a question whether this group should be separated from Ani.ms. The shell of strauchiami.s is similar in form to that of Anisus septongyratus, differing principally in the costate sculpture. Clessin's fig- ure (copied from Conch. Cab., XVII, plate 31, fig. 5) is reproduced on plate 76, fig. 3. The original description of the shell appears on page 204 of Clessin's work. 62 The Molluscan Family Planorbidae Subgenus BATHYOMPHALUS (Agassiz MS) Charpentier, 1837 Type Helix contorta Linn, designated by Herrmannsen in 1852 1837. Bnthyomphalus Agassiz (MS) Ch.arpentier, Neue Denkschr. AUg. Schweiz. Gesell., I, no. 2, p. 20. 1847. Polygyrus Gr.\y, Proc. Zool. Soc, p. 181. T^-pe Planorbis contortus (Linn.) (not of Say, 1818, or Beck, 1837). 1850. Discoidina Stein, Leben. Schneck. und Musch. Berlins, p. 82. Type Planorbis contortus (Linn.). 1852. Bathi/omphahis Herrm.annsen, Ind. Gen. Mai., II, Suppl., p. 16. Type Planorbis coJitortus (Linn.). 1855. Bathyomphalus Moquin-T.\ndon, Hist. Nat. Moll. France, II, p. 443. As sub- genus. 1870. Bathyomphalus D.\ll, Ann. X.Y. Lye. Nat. Hist.. IX, p. 352. Type Planorbis contortus (Linn.). As subgenus. 1883. Bathyomphalus Fischer, Man. Conch., p. 507. Tyi)e Helix contorta Linn. As section of Planorbis. 1885. Bathyomphalus Westerluxd. Fauna Palaearc. Reg.. V, p. 65. No tyjie cited. 1886. Bathyomphalus Clessix, Conch. Cab., XVII, p. 34. Type Planorbis contortus (Linn.). As subgenus. 1902. Bathyomphalus Westerluxd, Rad. Jugoslav. Akad., 151, p. 120. Type Helix contortus Linn. As genus of Planorbis. 1905. Bathyomphalus Dall, Alaska Moll., pp. 83, 86. Type Planorbus contortus (Linn.). As section of Planorbis. 1917. Bathyomphalus Soos, Ann. Musei Nat. Hungarici, XV, pp. 45, 142. Type Bathyomphalus contortus (Linn.). As subgenus. 1921. Bathyomphalus Germ.mn, Rec. Ind. Mus., XXI, p. 7. Type Planorbis contortus (Linn.). As subgenus of Planorbis. 1923. Bathyomphalus Wenz, Fossil. Cat., Pars 22, p. 1633. Genotype Bathyomphalus contortus (Linn.). As genus. 1926. Bathyomphalus Lixdholm, Archiv. fiir Mollusk.. 58 year. Heft 6, p. 253. Mon- ogenotype Planorbis contortus (Linn.). As genus. 1926. Bathyomphalus Kexx.ard and Woodward. Syn. British Non-marine Moll., p. 68. Type Helix contorta Linn. As subgenus of Planorbis. 1929. Bathyomphalus H.aas, Trab. Museo Cien. Nat. Barcelona, XII, j.. 383. Type evidently Planorbis contortus (Linn.). As genus. 1931. Bathyomphalus Germ.^in, Moll. Terr. Fluv. France, II, p. 520. Type evidently Planorbis contortus (Linn.). As subgenus of Planorbis. 1931. Bathyomphalus Thiele, Handbuch, IV, Teil 2, p. 481. Type Anisus (B.) con- tortus (Linn.). As subgenus of Anisus. 1935. Bathyomphalus Soos, Allat. Kozlem., XXXII, p. 30. Planorbis contortus (Linn.) cited. As genus. Shell (plate 77, figs. 23-25). Small, ultradextral with the whorls more nimierous and more closely coiled than in Anisus, increasing very slowly in diameter, equally visible above and below, but the spire whorls (left side) forming a wide depression, a false umbilicus, not present in Anisus. Animal. Not difi^ering in general characteristics from Anisus. ANATOMICAL CHARACTERISTICS PLATE 3 GENITALIA. Male Organs (fig. 10) . Seminal vesicle (SV) very long (3.5 mm.), of larger diameter than the ovisperm duct with many small tuberculous glands protruding from the surface. Prostate long (about 3 mm.) and composed of forty-eight to fifty relatively short and wide Subfamilies, Genera, and Subgenera — Recent and Fossil 63 diverticula (fig. 10, PRS, fig. 8). The i)rostate duct is a narrow tube about 1.5 nnn. long from the prostate to its junction with the sperm duct to form the vas deferens (fig. 10, PD, SPD). In the natural position the prostate lies over the sperm duct and until separated from this organ the prostate diverticula appear to be directly attached to the sperm duct (see fig. 8, PD). This junction is placed higher uj) on the uterus than in Planorbis or Anisus. The vas deferens is a long (4.5 mm.) narrow tube which enters the vergic sac without enlargement. The penial complex (fig. 9) is very long and narrow, the prcputium (PR) being a little more than half the length of the vergic sac (preputium 1.3 mm. vergic sac 2 mm.) . The narrow and cylindrical vergic sac is greatly contracted for about a third of its length near its connection with the preputium. There' is one long and narrow retractor muscle attached to the summit of the preputium. Internally, the anatomy of the penial complex is the same as in A?nsiis. Female Organs, The spermatheca is cylindrical, 1 mm. long, attached to the vagina by a narrow spermathecal duct a little more than 1 mm. long. The vagina (V) is very short (0.3 mm.) and wide. The uterus (U) is long (2 mm. long, 0.2 mm. wide) and narrowly cylindrical. The nidamental gland (XG) is long (about 3 mm.) and of larger diameter than the uterus (about 0.3 mm.). The oviduct (OD) is long (about 4 mm.) and narrowly cylindrical. The albumen gland is about the shape of that organ in Anisus (see plate 7, fig. 2). Hermaphrodite Organs. The ovotestis is like that organ in Planorbis and Anisus. The diverticula are long and cylindrical and packed closely on the ovisperm duct (plate 3, OT, fig. 7). The ovisperm duct lies at each end of the seminal vesicle, of about the same length in each division, (about 2 mm.) and is a small, smooth tube (SO). The figure in Germain (1931, pp. 521, 532) does not agree with the Poland specimens in all respects. The penial complex (p) shows the vergic sac as much swollen, while in the specimens examined it was long and narrowly cylindrical. The relative lengths of the female and male systems is shown much shorter than was observed in the Poland specimens. Details of the prostate and ovotestis are not shown. The spermatheca in both figures is the same. Soos's figure (1917, p. 47) is similar to the ones here presented and is somewhat clearer than those of Germain. The prostate shows the great number of short diverticula, the spermatheca is on a long duct, and the penial complex is like the Poland specimens here figured. Respiratory and Renal Systems. The pseudobranch (jilate 3, fig. 5. P) is about as in Anisu>i, but is smaller and narrower. The pneumostome (PS) is larger than in Anisus but is otherwise similar. The kidney (plate 46, fig. 19) is long and narrow (7 nnn. long, 0.5 mm. wide) with a sharply reflected ureter. A cross section of the kidney (fig. 20) shows a laterally jiyriform lumen with the veins at about the center of the section at each end. There is no ridge on the ventral side of the kidney but there is a rounded bulging on the left side that does not appear on the right side. Digestive System. The stomach (plate 48, fig. 8) is greatly elongated, pear-shaped, with a large blind sac, two-thirds as long as the stomach. 64 The MoUuscan Family Planorhidae The intestine crosses over the oesophagus and extends toward the forward part of the body, but there is no bending backward with a posterior loop as in the Helisoniatinae. As in Anisus, there is no sharp division into crop, gizzard, and pyloris. The pyloric portion of the stomach appears to merge with the intestine. Germain states that it is absent. The buccal sac is as in Anisus. The jaw is like that of Planorbis planorbis, the superior portion having about twentv plates. The radula (plate 68, fig. 1) formula is 15-1-15 with 140-145 rows of teeth. Central tooth bicuspid, nearly reaches to the lower margin of the base of attachment. Lateral teeth (1-8) are tricuspid with a small addi- tional cusp above the ectocone, placed high up on the reflection. The inter- mediate teeth (9-11) differ by having the reflection placed higher on the tooth, with four cusps, the ectocone split into three cusps. Marginals (12- 15) with five cusps are like the intermediate teeth, the reflection very high on the tooth. The outer marginal (15) is very narrow. For the anatomical data herein presented, four specimens were dis- sected, collected by A. Jankowski, at Drewnica, a turfy ground 4 km. northeast of Warsaw, Poland. Geographical Distribution. This group extends throughout Europe from the British Isles and Portugal eastward to Russia and Siberia, as far east as Kamchatka (Eyerdam, 1928). Southward the distribution in- cludes the countries bordering the Mediterranean Sea and the Caspian Sea. Species Considered as Valid. Ajiparently but two species are included in this group: Anisus ( Bathyoniphalus) contortus (Linn.) of Europe and Asia, and Anisus (Bathyoniphalus) dispar (Westr.) of Sweden and Russia. Geological Distribution. From the Miocene period to the Recent period. Remarks. In anatomical features Bathyoniphalus so nearly resembles Anisus that there seems little reason for recognizing the group as distinct. The genitalia strongly resemble those of Anisus septemgyratus. The in- ternal structure of the penial complex is similar. The kidney shows some differences in cross section (compare plate 46, fig. 20, with plate 47, figs. 14-16). However, the shell is distinctive and the name has been in use for so long a period that it should be retained as a subgenus of the old group Spiralina { = Anisus). It should be noted that the radula formula is the same as in Anisus and different from that of Planorbis. Genus ODONTOGYRORBIS Lorenthey, 1906 Type by original designation Planorbis krambergeri Halavats 1906. Odontogyrorbis Lorexthey, Beitrage zur Fauna unci stiatigraphischen Lage der pannonischen Schichten in der Umgebung des Balaton-Sees. Resultate d. wissenschaftl. Erforschung des Balatonsees, I, 1, Art. 3, p. 121. Genotype Planorbis krambergeri Halavats. 1923. Odontogyrorbis Wenz, Fossil. Cat., Pars. 22, p. 1538. Genotype Paraspira (Odontogyrorbis) krambergeri Halavats. As subgenus of Paraspira. Shell (plate 76, figs. 1, 2). Very small, discoidal, flattened, whorls rela- tively few, closely coiled, increasing very slowly in diameter, each side showing all of the volutions, right side slightly concave, left side almost flat; the aperture contains three lamellae, one on the base of the lip and Subfaf/iilies, Genera, and Subgenera — Recent and Fossil 65 two on the iipjxT part of the aperture. The whole edge of the aperture is thickened. Geological Distribution. Lower PHocene. Fonyod, Kenese, and Nagy- vazsong. Hungary. Remarks. This group is noteworthy for the presence in the aperture of three folds or plicae, whence the generic name Odontogyrorbis. In general form the shell is related to Anisus vortex (Linn.), but is very much smaller. Halavats original specimens (plate 76, fig. 1) were broken and did not have the folds in the aperture. Lorenthey obtained specimens with the lip entire (plate 76, fig. 2). Wenz (1923, p. 1538) made Odontogyrorbis a subgenus of Paraspira {= Anisus). While the shell does resemble the type of Paraspira [Planorbis leucosfonms ^Millet) no member of the genus Anisus has as yet been recorded from the recent fauna with a dentate aperture. For the present Odontogyrorbis should be treated as an extinct genus related to Anisus. Species Considered as Valid. Odontogyrorbis krauibcrgeri (Halavats) is the only si:)ecies here ascribed to the genus Odontogyrorbis. It is of interest to note that the Pliocene planorbid fauna of the Lake Balaton region consist of sixteen species, all but one of which are extinct, the Pleistocene fauna contains fifteen species and races all of which belong to the recent fauna. Some of the supposed extinct species are closely related to their recent allies and might be considered geologic variations of the recent forms, in fact, ancestral species. Genus GYRAULUS (Agassiz :MS) Charpentier. 1837 Type Planorbifi albii.s Miiller {^Planorbis hispidus Drap.) Designated by Dall in 1870. The first species originally included. 1827. Planaria (part) Brown, Illust. Conch. Britain, ed. 1, exphm. plate LI, figs. 48, 49. Xon Miiller 1886 and Golze 1782 (Vermes). 1837. Gyraulus (Agassiz MS) Charpentier. Xeue Denkschr. Allij. Schweiz. Gesell. I, no. 2, p. 21. 1840. Gyraidus H.artmaxn, Syst. Uebers. Euroji. Gattun. (Tableau). 1841. Trochlea Haldeman, Amer. Jour. Sci., XLII, p. 216. Xew name for Planaria. Brown. 1844. Gyraulus Hartmaxx, FAxi unil Siissw. Gaster. der Schweiz. V. p. 89. 1850. Nnutilina Stein, Leb. Schneck. und Muschl. Berlins, p. 80. Tyjie fixed by Clessin (1886) Planorbis albus Miiller. As synonym of Gyraulu.^. 1855. Gyraulus Moquin-Tandon, Hist. X"at. Moll. France, II, p. 438. X'o type cited. As genus. 1855. Giraulus Moquin-Tandon, op. cit., p. 423. Tyjiographical error for Gyraulus. 1857. Gyraulus Gray, Turtons Manual. 2nd Ed., p. 234. In sj'iionj-my. 1857. Gyrulus Gr.\y, op. cit., p. 234. Error for Gyraulus. 1865. Gyraidus W. G. Binney, L. & F-W Sh. X. A., II, p. 128. Xo type cited. As .sub- genus of Planorbis. 1870. Gyraulu.'i D.\ll, Ann. X. Y. Lye. X"^at. Hist., IX, p. 351. Type Planorbis albus Miiller. As subgenus of Planorbis. 1883. Gyraulus Fischer, Man. Conch., p. 507. Type Planorbis albus Miiller. As section of Planorbis. 1883. Caillaudia Bourciuign.at, Ann. Soc. Xat. Zool., (6), XV, p. 99. Monotype Cail- laudia angulata Bo\\rg. = Planorbis costulatus Krauss. (vide Pilsbrj' and Bequaert, 1927, p. 124). 66 The Molluscan Family Planorhidae 1884. Gyraulus Tryon, S. & S. Conch., Ill, p. 106. Example Planorbis deflectus Say. As subgenus or Planorbis. 1885. Gyraulus Westerlund, Fauna Palaearc. Reg., V, p. 75. Type Pkuiorbis albus Miill. As subgenus of Planorbis. 1886. Gyraulus Clessin, Conch. Cab., XVU, p. 33. Type Planorbis albus Miiller. As subgenus of Planorbis. 1899. Gyraulus Martens, Biol. Cent. Amer. Moll., p. 392. Type Planorbis albus Miiller. As subgenus of Planorbis. 1902. Gyraulus F. C. Baker, Moll. Chi. Area, II, p. 297. No type cited. As subgenus of Planorbis. 1902. Gyraulus Westerluxd, Rad. Jugoslav. Akad., 151, p. 121. Type Planorbis albus Miiller. As subgenus of Planorbis. 1905. Gyraulus Dall, Alaska Moll., pp. 83, 86. Type Planorbis albus Miiller. As subgenus of Planorbis. 1912. Gyraulus Hannibal, Proc. Mai. Soc. London, X, p. 154. Type Planorbis albus Miiller. As subgenus of Planorbis. 1915. Gyraulus Preston, Fauna Brit. India, Moll., p. 118. Type Planorbis albus Miiller. As section of Planorbis. 1917. Gyraulus Soos, Ann. Musei Nat. Hungarici, XV, pp. 54, 144. T.vpe Planorbis albus Miiller. As genus. 1918. Gyraulus Walker, Miscel. Pub., Mus. Zool., Univ. Mich., No. 6, pp. 12, 94. Type Planorbis albus Miiller. As subgenus of PUniorbis. 1919. Gyraulus Annand.\le and Prashad, Rec. Ind. Mus., XVHI, p. 52. Type Planorbis albus Miiller. As genus (genitalia and radula). 1921. Gyraulus Germain, Rec. Ind. Mus., XXI, pp. 8, 98. Tyi)e Planorbis albus Miiller. As subgenus of Planorbis. 1922. Gyraulus Annandale, Rec. Ind. Mus., XXIV, p. 361. Tyiie Planorbis albus Miiller. As genus. 1923. Gyraulus Wenz, Fos.sil. Cat., Pars 22, p. 1540. Genotype Gyraulus hispicbis Drap. = G. albus Miiller. As genus. 1926. Gyraulus Kennard and Woodward, Syn. British Non-Marine Moll., p. 67. Type Planorbis albus Miiller. As subgenus of Planorbis. 1926. Gyraulus F. C. Baker, Trans. Wis. Acad. Sci. Arts, XXII, p. 204. Type Planorbis albus Miiller. As genus. 1927. Gyraulus Pilsbry and Bequaert, Bull. Amer. Mus. Nat. Hist., LIII, p. 124. Type Planorbis albus Miiller. As subgenus of Planorbis. 1928. Gyraulus F. C. Baker, F. W. Moll. Wis., I, p. 364. Type Planorbis albus Miiller. As genus. 1929. Gyraulus H.\as, Trab. Museo Cien. Nat. Barcelona, XIII, p. 384. Type evidently Planorbis albus Miiller. As genus. 1931. Caillaudia Thiele, Handbuch, IV, 2nd Teil, p. 481. Type wrongly given as Anisus (C.) letourneuxi Bourg. (see Pilsbry and Bequaert, 1927, p. 124). As section under subgenus Armiger which is a subgenus of Ayiisus. 1931. Gyraulus Thiele, Handbuch, IV, 2nd Teil, p. 481. Type Planorbis albus Miiller. As section under genus Anisus. 1931. Gyraulus Germain, Moll. Terr, et Fluv. France, II, p. 533. No type cited. As subgenus of Planorbis. 1935. Gyraulus Soos, Allat. Kozlem., XXXII, p. 30. No type cited. As genus. Subgenus GYRAULUS SS. Type Planorbis albus Miill. Shell (plate 77, figs. 1-3). Small, ultradextral, of comparatively few flat- tened \vhorls, equally visible above and below, usually rapidly enlarging in diameter; body whorl at aperture usually somewhat deflected, the aperture oblique; the periphery is usually median and in some species carinate; the Suhjamilies, Genera, and Subgenera — Recent and Fossil 67 shell in several species is covered with short, hair-like projections of the periostracum (hirsute). Animal. External appearance (plate 70, fig. 5). The head bears the long, filiform tentacles characteristic of the Planorbinae with the eyes at the inner base. In general form the animal does not differ greatly from the figures of Tropicorbis on plate 78. No pigmentation, however, shows through the shell. ANATOMICAL CHARACTERISTICS PLATE 14 {Gyraulus albu.^) GENITALIA. Male Organs (fig. 7) . Seminal vesicle (SV) less than 1 mm. long, composed of a few large diverticula or glands three or four times the diameter of the ovisperm duct. Sperm duct about 2 mm. long, of small chameter. Prostate (PRS) relatively long (1.5 mm.) consisting of about 22 long (less than 0.5 mm.) diverticula attached to a separate prostate duct which is more than twice the diameter of the sperm duct. The free portion of the prostate duct is very short (0.2 mm.) and is of the same diameter as the sperm duct which it joins to form the rather short (1.2 mm.) vas deferens. A cross section through the prostate near the anterior end shows the sperm duct behind the prostate (fig. 9, SPD). The penial complex (fig. 2) is cylindrically elongated, a trifle more than 1 mm. long, the vergic sac (VS) somewhat shorter than the preputium (PR). There is one long retractor muscle (R^I). The vas deferens is not enlarged as it enters the vergic sac. Internally (fig. 1) the preputium has thick walls, two pilasters, a muscular ring or diaphragm (D), and a de- pendent papilla (PP). The vergic sac has thin walls which increase in thickness toward the preputium. The verge (V) is elongate-pyriform, narrowed at the lower end where there is a stylet (ST). The stylet (fig. 8, ST) is dark brown, dagger-like with a ridge extending down the center. The opening of the sperm canal (SC) turns to one side above the stylet and has its exit on the side of the verge. Female Organs. The spermatheca (fig. 7, S) is elongate-pyriform, about 0.5 mm. long. It is joined to the vagina by a short, narrow duct about half as long as the spermatheca (SD). The vagina (VG) is very short and wide. The uterus (U) is wider than the vagina and the nidamental gland is wide and made up of many large diverticula (fig. 6, NG I . The uterus and gland are hidden in the figure by the large prostate. The free oviduct (fig. 6, OD) is a short and narrow tube, looped beneath the prostate. Figure 6 shows the relationship of the nidamental gland diverticula, the oviduct, the prostate, the sperm duct, which forms a loop, and the method of junc- tion to form the ovisperm duct. The narrow duct of the albumen gland and its connection with the oviduct is shown. The albumen gland is squarish or oval in shape and is composed of large gland cells. It contains cavities for the loop of the intestine, over which it lies (fig. 5). Hermaphrodite Organs. The ovotestis (OT) consists of a double row of pyriform diverticula attached to a large ovisperm duct (fig. 10). At the posterior end of the ovotestis the diverticula are crowded together (fig. 11). Several diverticula had developing egg cells. The ovisperm duct (SO) is divided into two parts, one at each end of the seminal vesicle (fig. 7, SO). The figures on plate 14 agree with that of Germain (1931, p. 533, fig. 545). His figure, however, is not very clear. Soos's figure (1917, p. 55) is 68 The MoUuscan Family Planorhidae similar in general form. The prostate shows fewer diverticula, however, and the spermatheca is on a longer duct than in the specimens from Poland examined, and they are figured more irregularly than was observed in the specimens j^ersonally examined. A. Soos's figure of Gyraulus laevis I Aid.) (1935, p. 27) shows a smaller number of prostate diverticula than appears normal for the genus. The spermatheca is also on a longer duct than in those species of the genus personally examined. No separate prostate duct is indicated. American species examined differ but little from the European Gyraulus albus. Gyraulus hirsutus (Gould), the nearest relative to albus, has from twenty to twenty-two diverticula on the prostate as in albus (plate 15, fig. 2). The seminal vesicle is practically the same. The penial complex has a much shorter preputium with a vergic sac one and one-half times as long as the preputium. This difference in form of the penial complex easily separates albus from hirsutus (compare fig. 2, plate 14, with fig. 2, plate 15). In Gyraulus deflectus obliquus (DeKay) there are forty divertic- ula on the prostate which is much longer than either albus or hirsutus. The prostate diverticula are also longer and club-shaped toward the end (plate 16, figs. 11, 12). Plate 16 fully illustrates the genitalia of obliquus. Gyraulus latestomus F. C. Baker (plate 19, fig. 9) has thirty-two diver- ticula on the prostate and the penial complex resembles that of obliquus. Gyraulus conve.vius cuius (Hutton) (plate 19, fig. 2) of India has about twenty-five prostate diverticula. The penial comjilex is very long and narrow but generally resembles that of hirsutus. The figures on plate 19 agree with tliose by Annandale and Prashad (Rec. Ind. Mus., XVHI, p. 40) except that the spermatheca in the specimens examined is on a much longer duct than is shown in their figure. Respiratory and Renal Systems. The pseudobranch of Gyraulus albus (plate 14, figs. 3, 4) is broad, somewhat triangular, and flattened. The pneumostome is broad (fig. 3, PS). Figure 4 shows the pseudobranch cut open to indicate the vascular network of blood vessels. The rectum passes through the pseudobranch, as in other genera of Planorbinae. In Gyraulus hirsutus (plate 15, fig. 3) the pseudobranch is as broad as in albus. In Gyraulus deflectus obliquus the pseudobranch was observed to be of several forms (plate 16, figs. 13, 14, 15). It is in each case a broad, flattened organ. Figure 15 is an unusual form, possibly pathologic. In Gyraulus latestomus (plate 19, fig. 8) it is broad and flattened. In Gyraulus convexi- uscidus, from India (plate 19, fig. 3) it is flat and very thin and the pneu- mostome is very large. The pseudobranch appears to be similar in form in species from Europe, America, and India. The kidney (plate 48) is long and narrow in obliquus (fig. 4, 9 mm. long) and conve.xiusculus (fig. 17, 8.5 mm. long). In hirsutus (fig. 18, 2.5 mm. long) and albus (which has the same form as hirsutus) the kidney is short and wide, quite unlike the kidney of the two species previously men- tioned. It is similar to that of vermicularis (fig. 3). Sections through the kidneys at about the middle show this organ to be flattened, the lumen much wider than high, and the veins to be placed at each end at about the center. Conve.vius cuius (fig. 8), hirsutus (fig. 19), and latestomus (fig. 11) are similar in form, but obliquus (fig. 10) is higher in proportion to width showing that the kidney is thicker than in the other species. There is no ridge. The ureter is short in convexiusculus and obliquus but longer and more tube-like in hirsutus and albus. SuhjamUies, Genera, and Subgenera — Recent and Fossil 69 Digestive System. The stoiiiacli (plate 48, fig. 13j is cylindrical with the crop, gizzard, and jndoris plainly indicated. The intestine, after leaving the in'loris, makes a looj) over the oesophagus which extends backward, around the liver, and then loops forward to the rectum which has its exit on the pseudobranch. All species of typical Gyraulus examined have the same type of stomach and intestine. The buccal sac (of Gyraulus albun plate 70, fig. 13) is pyriform with the radula sac greatly developed and protruding behind (RL). The salivary glands (SG) are elongated, cylin- drical, and almost as long as the buccal sac. The ducts of these glands are long. The jaw (plate 50) is horseshoe-shaped and fragmented as in Planorbis and Anisus. Gyraulus hirsutus (fig. 17) has large plates, about forty on the entire jaw. Gyraulus albus has the same number. In Gyraulus dejiectus obliquus (fig. 18) the jaw is arched and consists of over fifty plates which are narrower than those of albus and hirsutv^. In latestomus the jaw is similar to that of obliquus and has over forty plates. The radula formula of Gyraulus albus (plate 68, fig. 9) is 18-1-18 with 103 to 114 rows of teeth. The center tooth is bicuspid, the cusps long and narrow and reaching only about half waj- to the lower margin of the base of attachment. The laterals (1-9) are tricuspid with long, narrow cusps. The cusps of intermediate teeth ( 10-11 ) are short, placed high up on the re- flection, and the ectocone is split into two sharp cusps. The marginal teeth (12-18) have the reflection high up on the tooth, are wide and low and 6-cuspid. The entocone is split into two small cusps, the mesocone is larger, and the ectocone cusps, three in number, are very small and sharp. In sev- eral membranes examined a very small 4th cusp appears on the 6th tooth and continues to the intermediate teeth. The center tooth varies in size in the 43rd to 62nd rows being a trifle wider at the top than in the first forty- two rows. The 86th to 103rd rows have a central tooth a little more than half the width of those in the 43rd to 62nd rows. The radula of Gyraulus hirsutus (plate 69, fig. 1) is similar to that of albus. The formula is 19-1-19, with 1-9 lateral teeth, 10-11 intermediate teeth, and 12-19 marginal teeth. There are 130 rows of teeth. The radula of Gyraulus dejiectus obliquus (plate 69, fig. 2) has a formula of 22-1-22, with 1-9 lateral teeth, 10-13 intermediate teeth, and 14-22 marginal teeth. There are 175 to 183 rows. Gyraulus latestomus has the formula 20-1-20, with 1-10 marginal teeth, 11-14 intermediate teeth, and 15-20 marginal teeth. There are 155 rows of teeth. Gyraulus convexiusculus has the formula 20-1-20, with 1-9 lateral teeth, 10-13 intermediate teeth, and 14-20 marginal teeth. The specimens examined differ from the figure by Annandale and Prashad (Rec. Ind. AIus., XVni, p. 55, fig. 8, B) where the inner laterals are shown as bi- cuspid, an unusual condition in the genus. Probably the entocones were not observed, for they were present in all of the laterals of the teeth per- sonally examined. The figure of the radula of Gyraulus euphraticu^ (C) by Annandale and Prashad is more correct in the tricuspid character of the lateral teeth. The radulae of all of the typical Gyraidus examined have been similar in character. For the above anatomical data the following material has been available: G. olbu.s, 25 specimens from park in Krolikarnia, a suburb of "Warsaw, Poland. Collected bv Mr. A. Jankowski. 70 The Molluscan Family Planorbidae G. hirsutus, 9 specimens from mouth of Bass Creek, Lake Xipissing, Ontario. Col- lected by Mr. A. LaRocque. G. deflect us obliquus, 13 specimens from Lake Chetek, Wisconsin. Collected by F. C. Baker; 6 specimens from Taylors Lake, near Quebec, Canada. Col- lected by Mr. A. LaRocque. G. latutomus, 3 specimens from Cedar Lake, Algonquin Park, Ontario. Collected by Mr. A. LaRocque. G. convexiusculus, 3 specimens from Calcutta. India, collected bj' Dr. B. Prashad. Geographical Distribution. The genus Gyraulus is practically world- wide in distribution, differing in this respect from all other genera of Planorbidae. Specific regions include North America, parts of the West Indies and northern South America, Europe, Asia, Africa, Australia, Malaysia, Fiji, New Caledonia, Philippines, and other islands of the Pacific Ocean. Below is given a list of some of the species of Planorbids believed to belong in the genus Gyraulus* Some of these species may be found, on anatomical examination, to belong to other subgenera or genera. The list is probably not complete. Species of Europe and Western Asia alhus Mliller acronicua Ferussac ancylus West. arcticus M oiler albopersicus Germain borealis Loven hourguignati Moitessier brondeli Raym. capocestianus V. Brus. crossei Bgt. devians Porro drapanauldi Jeff. gredleri Bietz he bra if us Bgt. infraliratus West. intermixtuii Mouss. janinensis Mouss. laevis Alder Umnophilus West. numidicus Bgt. piscinarum Bgt. polaris West. regulosus Lindholm socius West. tctragyrus West. Species of Australia and Tasmania essingtoneiisis Smith meridional^ Brazier gilberti Dunker planissimus Mousson Species of Africa abyssinicus Jickeli adansonii J. E. Gray aethiopicus Bourg. agraulus Boiu'g. andcrsoni Ancey avakubiensis Pils. and Beq. chedeaui Germain cockbruni Godwin-Au.sten costulatus Krauss crmvfordi Melville and Ponsonby fouladougouensis Germain gardei Germain gibbonsi Nelson kigeziensis Preston kisumieiisis Preston lamyi Germain leucochilus Melville and Ponsonby niisellus Morelet natcderuiia Krauss sperabilis Preston schweinfurthi Clessin tilhoi Germain toukotoensis Germain *In this faunal list, which Mr. Baker had never fully edited, the author's name follows each specific name with disregard for use of parentheses to indicate change from original generic assignment. — H.J.V-C. Subjani'dies, Genera, and Suhgeuera — Recent and Fossil 71 Species of Fiji Group singularis Mousson Species of New Caledonia montrouzieri Gassies Species of associatus Westerlmui ocutua Clessin barrakporensis Clessin cnntori Benson cherraeiisis Godwin- Austen compressus Hut ton convexiusculus Hutton demissus Westerlund elegantulus Dohrn euphraticibs Mousson himlayaensis Hutton hohcnachcri Clessin haltoni Benson hiiptiocyclos Benson injraUneatus Martens intcrmixtus Mousson issykulensis Clessin i-us-siteri Crosse India and Asia labiatus Benson laidocensis Nevill liratus Westerlund nialacaensis Germain pangongensis Nevill proclivis Martens rotuln Benson saigonensis Crosse and Fischer saltensis Germain sivalensis Hutton stelzneri Dohrn stewarti Germain sumatranus Martens tondanensis Quoy and Gaimard velijer Annandale yeni Ping and Yen Species of Japan amplificaius Mori biwaensis Preston hiemantium Westerlund infirmus Mori iwaotakii Mori Species of the Philippines ?)titidanensis Bartsch quadrasi Mollendorff japonicus Martens noziriensis Mori pulcher Mori tokyoensis Mori Species of America arcticioi (Beck in Moller) boetzked (Miller) burealis Lo\'en cyclostomus F. C. Baker dcflectus (Say) deflectus obliquus (De Kay) hirsutus (Gould) hornensis F. C. Baker Intistoiinis F. C. Baker Geological Distribution. According to Wenz the genus Gyraulus dates geologically from the Middle Eocene period. Remarks. The genus Gyraulus is closely related to Anisus in its ana- tomical features, especially the genitalia. In fact, Gyraidus, A7iisus, and Bathyomphalus form a natural group, based on their anatomy, particularly in the presence of a horny stylet on the verge. The shells of Anisus and Gyraulus, however, are quite unlike and the genera should undoubtedly be separated on conchological grounds alone. ]\Iore than ninety species of Gyraulus are listed on the previous pages (excluding those from America). Some of these may be found to belong in other genera, when examined anatomically. Also, it is probable that several additional species should be added to those listed. Completeness is not claimed. All of those listed have been included in the genus Gyraulus by competent conchologists. 72 The Molluscau Family Planorhidae Subgenus TORQUIS Dall, 1905 Type by original designation Planorbis parvus Say 1899. Gyrcudus (part) Martens, Biol. Cent. Amer., Moll., p. 392. Includes Planorbis parvus Say. 1905. Torquis Dall, Alaska Moll., pp. 83. 86. Type Planorbis parvus Say. As section of subgenus Gyraulus. 1918. Torquis W.\lker, Miscel. Contr., Mus. Zool., Univ. Mich., No. 6, pp. 34, 94. Type Planorbis parvus Say. As section of subgenus Gyraulus. 1921. Torquis Germain, Rec. Ind. Mus., XXI, pp. 8, 150. Type Planorbis parvus Say. As subgenus of Planorbis. 1923. Torquis Wenz, Fossil. Cat., Pars 22, p. 1627. Genotype Gyraulus (Torquis) Say. As subgenus of Gyraulus. 1926. Torquis Kennard and Woodw.\rd, British Xon-Marine Moll., p. 67. As section of Gyraulus in synonymy. 1926. Torquis F. C. Baker, Trans. Wis. Acad. Sci. and Arts. XXII, p. 204. Type Pla- norbis parvus Say. As subgenus of Gyrajilus. 1928. Torquis F. C. Baker, Fresh-water Moll. Wis., I, p. 373. Type Planorbis parvus Say. As subgenus of Gyraulus. Shell (plate 77, figs. 4-6). Ultradextral, smaller than Gyraulus, SS, with the whorls less distinctly spirally striated, not hirsute, the base (left side) more or less concave, or excavated (appearing as though reamed out), the lip often slightly thickened within. Animal. Not differing from Gyraulus in general form. ANATOMICAL CHARACTERISTICS PLATE 17 (Gyraulus parvus) GENITALIA. Male Organs (fig. 6) . Seminal vesicle (SV) short (0.5 mm.) of the same diameter as the sperm duct. There are a number of small glands which stand out like pustules. Sperm duct a trifle more than 1 mm. in length. Prostate (PRS» more than half as long as the sperm duct with eleven long and cylindrical diverticula. The free portion of the prostate duct is very short (PD), joining with the sperm duct to form the vas deferens. A cross section through the prostate shows the cylindrical or pear-shaped diverticula on a separate duct which has a greater diameter than the sperm duct (fig. 10). The vas deferens is at first a large duct but becomes smaller in diameter toward the penial complex (VD). It is about 1 mm. in length. The penial complex (fig. 6, VS, PR) is very long (about 1.3 mm.) and narrow, and cylindrical. The vcrgic sac is longer than the preputium. There is one large retractor muscle attached near the junction of the vergic sac with the preputium (fig. 12, RIM). The vas deferens is not enlarged as it enters the vergic sac. Internally (fig. 12) the preputium has two vertical pilasters. The vergic sac is long and cylindrical and is enlarged at the upper end (VS). The verge (V) is long and narrow, enlarged at the upper end, very narrow below where there is a horny stylet (ST). The opening of the sperm canal is on the side as in typical Gyraulus. Between the vergic sac and the preputium there is a large papilla and below this a swelling of the wall of the preputium representing the better-developed muscular ring or diaphragm of typical Gyraulus (not shown in the figure). Female Organs. The spemiatheca (fig. 6, S) is small, pyriform, and connected with the vagina by a duct about as long as the spermatheca Subfamilies, Genera, and Subgenera — Recent and Fossil 73 fSD). The vagina is narrow and about as long as tlie spernuitheca and its duct. The uterus and nidamental gland are relatively short and wide (U). The oviduct is short (about 0.5 mm.). The junction of the oviduct and sperm duct to form the ovisperm duct is shown in fig. 7. The albumen gland is squarish in form, longer than wide (about 1 mm. long), and is composed of large diverticula. Its duct is long and looped (fig. 9, DA). Hermaphrodite Organs. The ovotestis is rather short and is composed of Init few club-sha})e(l diverticula arranged in a double row (fig. 6, OT; fig. 11). The ovisperm duct is small and tube-like and is longer between the seminal vesicle and the ovotestis than between the seminal vesicle and the oviduct (fig. 6, SO). Several of the diverticula of the ovotestis were filled with ova ready for extrusion (fig. 11). Several other species of the subgenus Torquis have been dissected and may be compared with parvus. Gyraidus circumstriatus (Tryon) (i)late 17, fig. 1, also fig. 4) is similar in form. The prostate has twelve diverticula. The spcrmatheca is the same. The duct to the albumen gland is not so long ( fig. 2) . The penial complex is the same in both species which are of about the same size. In Gyraulus vermicularis (Gould) there are sixteen diver- ticula in the prostate and ten diverticula in the ovotestis (plate 15, fig. 10). The penial complex is somewhat different, the preputium being long and cylindrical and the vergic sac very short, only about half as long as the preputium. In Gyraidus similaris (F. C. Baker) (plate 18, fig. 1) there are nineteen diverticula on the prostate and the ovotestis diverticula are few in number. In the penial complex the vergic sac is shorter than the preputium. There is a heavy swelling at the upper part of the preputium where the papilla and muscular ring are located. A section through the penial complex (fig. 3) shows the relationship between the several organs. The verge is very long and slender and has a large stylet (fig. 4). The junction of oviduct, sperm duct, and ovisperm duct is shown in fig. 2. The genitalia of the subgenus Torquis differ from those of typical Gyraidus in the form of the seminal vesicle, the fewer diverticula of the prostate, and the rounder spermatheca on a shorter duct. In general, how- ever, the two groups are very similar in the form and position of the genital organs. No figures of the genitalia of the Torquis group have been iniblished jireviously; hence no comparisons can be made. Respiratory and Renal Systems. The jiseudobranch of Gyraidus parvus (plate 17, fig. 8) is flattened, wide, leaf-like, and is pierced by the rectum. The pneumostome is very large. In Gyraulus circumstriatus (fig. 3) the pseuclobranch is much narrower (the animal was much contracted). In Gyraidus vermicularis (plate 15, fig. 8) it is flattened and somewhat tri- angular. In Gyraulus similaris (plate 18, fig. 5) it is like that of vermicu- laris but the rectum has a slight ridge which was not observed in any of the other species examined. In the four species of this group studied there was a large, flattened, muscular jiad extending backward from the free portion of the pseudobranch to the place where the rectum begins on the intestine. Figure 5 on plate 18 and fig. 8 on plate 15 show the form of this pad. The rectum pierces this pad as well as the pseudobranch and has its exit (A) above the leaf-like pseudobranch. The kidney (plate 47, fig. 1, parvus) is very long and narrow (4 mm. long, 0.5 mm. wide), the ureter short and recurved. In Gyraidus circum- 74 The Molluscan Family Planorhidae striatus (fig. 2) the kidney is much shorter and wider (less than 2 mm. long). In vermicularis it is short and wide as is also the case in similaris. Cross sections through the kidney of the four species show a similarity of conditions (fig. 5 parvus; fig. 6 circumstriatus ; fig. 7 vermicularis; fig. 9 similaris). The kidneys in Gyraulus and Torquis differ little in structure. Digestive System. The digestive tract shows division into crop, gizzard, and pyloris and there is a large blind sac. The intestine does not form a posterior loop, as in typical Gyraulus, but crosses over the oesophagus and extends forward as in the genus Planorbis. The buccal sac is like this organ in typical Gyraulus. The jaw (plate 50, fig. 16, parvus) is horseshoe-shaped with many small plates as in Gyraulus typical. There are approximately thirty-six to forty plates on the jaw of parvus and Gyraulus vermicularis has about forty-seven plates (fig. 19). Gyraulus circumstriatus (fig. 22) has a small, narrow jaw with about thirty-seven plates. The jaws of Gyraulus (figs. 17-18) are not as typically horseshoe-shaped as in the subgenus Torquis. The radula formula of Gyraulus parvus (Say) is 14-1-14 with 105 rows of teeth (plate 69, fig. 3). The center tooth is bicuspid, the cusps not reaching the lower margin of the base of attachment. There are 1-6 lateral teeth, tricuspid, with spade-shaped cusps. Intermediate teeth (7-8) with the ectocone split into two small cusps. The 9th tooth is also transitional with the ectocone split into three small cusps. Typical marginal teeth (10-13) have the entocone split into two small cusps, the mesocone large and spade-shaped, and the ectocone split into three small cusps. In Gyrauliis vermicularis (Gould) (fig. 5) the formula is 15-1-15, with 1-6 laterals, 7-10 intermediates and 11-15 marginals. There are 120-125 rows of teeth. In Gyraulus similaris (F. C. Baker) (fig. 4) the formula is 22-1-22 with 1-7 laterals, 8-10 intermediates, and 11-22 marginals. There are 130 rows of teeth. Gyraulus circumstriatus (Tryon) has the formula 14-1-14 with the same number and position of teeth as in parvus. The radula teeth of the subgenus Torquis do not differ in general character- istics from those of typical Gyraulus. Compare figs. 1, 2 with figs. 3, 4, 5 on plate 69. For the above anatomical data the following specimens were studied : Gyraulus parvus (Say), 14 specimens from Winnebago Lake, Wisconsin, Henry Co., Illinois, and Meach Lake, Canada, collected by F. C. Baker and A. LaRocque. Gyraulus circumstriatus (Tryon), 17 specimens from Wainwright Park, Alberta, col- lected by Dr. Swales, and North Star Lake, Wisconsin, collected by F. C. Baker. Gyraulus vermicularis (Gould), 10 specimens from Mt. Lake, San Francisco, California, and Hat Creek, Bishop, California, both lots collected by Dr. G. D. Hanna. Gyraulus .siyiiilaris (F. C. Baker), 17 specimens from Smartweed Lake, Toland, Colo- rado, collected by Dr. Frank Smith. Geographical Distribution. The subgenus Torquis is found throughout North America from Mexico northward. It is also apparently represented by Gyraulus santacruzensis Germain from the Island of St. Croix, West Indies. Gyraulus laevis Alder, a common species of Europe, also belongs to this subgenus. Some of the other species listed under the distribution of typical Gyraulus may belong to Torquis, but not enough material is avail- able for study to confirm this suggestion. Subjcunilics, Goiera, and Subgenera — Recent and Fossil 75 Species Considered as Valid. The American species included in tliis subgenus are: Gyraiilus (Torqids) aeruginosus GtjmuJus (Torquis) parvus (Say) Morelct Gyrauhts (Turquis) mntacruzensis Gyrauluti (Torquis) arizonensis (Germain) Pilsbry and Ferriss Gyrnuluj< (Torquis) siniildris Gyraulus (Torquis) allissimus (F. C. Baker) (F. C. Baker) Gyraulus (Torquis) vcrDiicularis Gyraulus (Torquis) carus (Gould) Pilsbry and Fcrriss (hjrnulus (Torquis) vermicukiris Gyraulus (Torquis) circuinstrint as hendcrsoni Walker (Try on) Gyra ul us ( Torq uis ) circ u ni s[ ria tus u'nlkcri Vanatta Geological Distribution. Torquis apparently dates geologically from the Oligocene period. Torquis siliceus Pilsbry and Brown, Oligocene of Dry Hill, Antigua. Remarks. Except for some small details in genitalia, referred to on a ])revious page, the subgenus Torquis is similar in anatomical details to typical Gyraidus. It is, however, a convenient name for the smaller species with 'reamed out' left side, like parvus and vermicularis, which have nar- rower and smoother whorls than the species of typical Gyraulus, like alhus and de flee tus. Genus ARMIGER Hartmann, 1840 Type by designation of Hartmann in 1842, Nautilus crista Linn. 1840. Armiger Hartmann, Syst. ubers. Em-op. Gatt., table. 1842. Armiger Hartmann, Erd-und Siiss. Gasterop., V, pp. 172, 219. Tyjie Armiger cristatus Drap. = Nautilus crista Linn. 1847. Nautilus Gray, Proc. Zool. Soc, p. 181. Type Turbo nautilus Linn. 1850. Nautilina Stein, Leben. Schneck. und Musch. Berlins, p. 81. Ideogenotype Pln- norbis nautilus Stein = Planorbis cristata Drap. Type designation by Lind- holm in 1926. 1885. Armiger Westerlund, Fauna Palaearc. Reg., V. i*. 65. No type cited. As sub- genus of Planorbis. 1902. Aryniger We.sterlund, Rad. Jugoslav. Akad., 151, p. 121. Type Turbo nautilus Linn. As subgenus of Planorbis. 1903. Spiniformis Germain, Bull. Soc. Sci. Nat. Quest France, ii. III, p. 204. Vide Germain, 1931. 1905. Armiger Dall, Ala.ska Moll., pp. 83, 86. Type Planorbis crista (Linn.). As sec- tion of subgenus Gyraulus. 1918. Armiger W.alker, Miscel. Contr., Mus. Zool., Univ. Mich., No. 6. pp. 13, 94. Tj'pe Planorbis crista (Linn.). As section of subgenus Gyraulus. 1923. Armiger Germain, Rec. Ind. Mus., XXI, pp. 8, 153. Type Plariorbis crista (Linn.). As subgenus of Planorbis. 1923. Armiger Wenz, Fossil. Cat., Pars 22, p. 1625. Genotype Gyraulus (Armiger) crista (Linn.), As subgenus of Gyraulus. 1926. Armiger Lindholm, Archiv. fiir Mollusk., 58 year. Heft 6, p. 253. Monogenotype Armiger cristatus T)rap. = Planorbis crista (Linn.). As genus on conchological grounds. 1928. Armiger F. C. Baker, Fresh-water Moll, of Wisconsin, I, p. 385. Type Nautilus crista Linn. As subgenus of Gyraulus. 1929. Armiger H.\As, Trab. Mu.seo Cien. Nat. Barcelona, XIII, p. 386. Type evidently Nautilus crista Linn. As genus. 76 The Molluscau Family Plauorbidae 1929. Armiger Odhxer, Die Mollusk. Fauna Takern, p. 22. Type Armiger crista (Linn.). As genus on anatomical grounds. 1931. Artniger, Germ.^in, Moll. terr. fluv. de France, II, j). 540. Type Plonorbis crista (Linn.). As subgenus of Planorbis. 1931. Armiger Thiele, Handbuch, IV, Teil 2, p. 481. Type Anisus (Armiger) crista (Linn.). As subgenus under Anisus. 1935. Armiger A. Soos, Allat. Kozleni., XXXII, p. 30. As subgenus of Gyraulus. No type indicated. Shell (i)late 76, fig. 6). Ultradextral, small, with few rapidly increasing, costate whorls, the costae usually projecting at the periphery. The general form is like that of Gyraulus. Animal. External form like that of Gyraulus. ANATOMICAL CHARACTERISTICS PLATE 18 GENITALIA. Male Organs (plate 18, fig. 7) . Seminal vesicle (SV) with very few large glands or diverticula. Sperm duct 1.5 mm. long, bent upon itself in a loop posterior to the prostate. Prostate 0.5 mm. long, consisting of thirteen long, cylindrical diverticula placed on a separate prostate duct. The free portion of the prostate duct is very short. Vas deferens a long (1 mm.), small duct. Penial complex (fig. 7) with a vergic sac one and one-half times as long as the preputium. The vergic sac is enlarged at the end w^here the vas deferens enters it as an enlarged tube. There is one retractor muscle (RM). The preputium is of larger diameter than the greater part of the length of the vergic sac. Internally (fig. 9) the j^enial complex is formed like that of Gyraulus. There are two }ulasters, a dependent papilla (D), and also a muscular ring or diaphragm (not shown in figure). The verge (V) is elongated, cylin- drical, tapering gradually to the end, which does not bear a horny stylet, as in Gyraulus, but a small, pointed fleshy papilla (fig. 10, PA, fig. il, PA). The opening of the sperm canal is just above this papilla at the end of the verge, in the center and not at the side as in Gyraulus (figs. 10, 11, SC). Female Organs, The spermatheca (S) is long and pyriform in shape, taj^ering gradually to the short, wide vagina (VG) , the duct being very short. The uterus (U) and nidamental gland are wide, the uterus short and the gland rather long. The oviduct (OD) is short and greatly swollen below the junction with the sperm duct to form the ovisperm duct. The albumen gland (fig. 8) is large (1 mm.), elongated and composed of large gland cells. It is joined to the large, bulbous carrefour (CF) by a long, very fine duct (DA). The carrefour connects with the oviduct. The intestine ex- tends the whole length of the albumen gland which covers the greater jmrt of the intestine. The space occupied by this organ is shown in the figure (AL). Hermaphrodite Organs. The ovotestis (OT) consists of many club- shaped diverticula placed in a double row. The ovisperm duct (SO) is twice as long between the oviduct and the seminal vesicle as between that organ and the ovotestis. No figure of the whole genitalia of Armiger was available before the publication of A. Soos's paper in 1935. His figure (1935, p. 28) differs in several respects from the ones here presented. The prostate has nine Subfamilies, Genera, and Subgenera — Recent and Fossil 77 divertieuhi which upi)ear widely fjpaeecl while there were thirteen crowded diverticula in the specimens personally examined. The separate prostate duct is not shown in Soos's figure. The spermatheca in Soos's figure is also on a longer duct. The penial complex differs in several respects. In 1929 (p)). 22, 30) Odhner called attention to the absence of a stylet in Armigcr, figured the verge of Anniger crista to show the absence of the stylet and the i)resence of a small penial i)apilla. This is, apparently, the first indication of this anatomical difference between Armiger and Gyraulus. Odhner noted a difference in the size of the teeth and formula of crista, those from the Takern having much smaller teeth than specimens from near Stockholm. The formula, also, was only 11-1-11 while the larger form has a formula of 14-1-14. Germain (1931, ii. 540) says 'Appareil genital comme chez les especes du sous-genre Gyraidus.' But this is not the case. There is no stylet at the end of the verge and the opening of the sperm canal is at the center beside a small papilla and not at the side above a stylet as in Gyraulus. The seminal vesicle is also different in form of glands. These differences in anatomy are sufficient to remove Armiger as a subgenus of Gyraulus and indicate its right to full generic rank. The genitalia of Armiger and Torquis may be compared on i^late 18, where the difference in the structure of the termination of the verge is i)lainly indicated. Respiratory and Renal Systems. The pseudobranch (plate 18, fig. 6) is broadly triangular, leaf-like. The rectum is a large tube bordering the upper side of the pseudobranch and the anus is above the pseudobranch. The kidney (plate 47, fig. 20) is short and wdde, somewhat resembling the kidney of Gyraidus vermicularis (fig. 3). A section through the kidney near the middle (fig. 21) shows it to be flattened, convex above, with the veins near the center of each side of the oval lumen. The section is also similar to that of Gyraulus vermicidaris (fig. 7). Digestive System. In the region of the stomach (plate 48, fig. 15) there is a distinct division into crop, gizzard, and pyloris. The intestine makes a loop forward and then backward under the oesophagus. It bends around the liver and turns forward, ending in the rectum on the pseudobranch. The stomach region resembles that of Gyraulus (fig. 13). The buccal sac is like that of Gyraidus. The jaw (plate 50, fig. 20) is narrow and characteristically horseshoe- shaped with the lateral processes elongated. There are twenty-two plates in the upper or superior jaw and fourteen to sixteen plates in each of the side jaws. The jaw most nearly resembles that of Gyraidus circumstriatus (fig. 22) except that it bears a larger number of plates. The radula formula is 16-1-16 with 150 rows of teeth. The center tooth is bicusj^id and resembles that of Gyraulus vermicularis (fig. 5). The laterals are four-cuspid (1-9), the intermediate teeth (10-11) five-cuspid, and the marginals (12-13) six-cuspid. The outer marginals are vestigial. The teeth resemble those of Gyraulus except that there is always an accessory cusp above the ectocone, even in the lateral teeth. For the above anatomical data ten specimens were dissected, collected from a swamp on University Bay, Lake ]\Iendota. near [Madison, Wiscon- sin, by Dr. J. P. E. [Morrison. These represent the variety i}nbricatus. Typical crista from a pond in Krolikarnia, a suburb of Warsaw, Poland, collected by A. Jankowski. provided most of the anatomical data. 78 The Molluscan Family Plauorbidae Geographical Distribution. Armiger is Palearctic in distribution, oc- curring in the northern United States and Canada, northern Europe and Asia. Armiger crista is reported from the trans-Mediterranean region, from Algeria, Tunis, etc. A species {Armiger annandalei Germain) has been described from eastern Asia. The genus contains several forms which should probably rank as species. Geological Distribution. According to Wenz (pp. 1632-1633) Armiger is first known from the Middle Miocene period. Species Considered as Valid. The only species definitely assigned to this genus in the present volume are: Armiger crista (Linn.) Armiger imhricatus (Miiller) Armiger crista spinulosum Armiger annandalei (Germain) (Clejsin) Remarks. By the form of the penial complex tliis group is distinct from Gyraulns and should be considered as of full generic rank. L. Soos (1917) and A. Soos (1935) list it as a subgenus of Gyraulus, but the lack of a penial stylet removes it from that group. Lindholm (1926) considers it a genus. Thiele (1931) considers it a subgenus of Anisus. Odhner (1929, p. 30) gives the group full generic rank on the basis of the lack of a stylet on the verge which is characteristic of Gijraulu^^. A good figure of the verge of Armiger crista, showing the small penial jjapilla at one side of the sperm outlet, is shown (fig. 10). Haas (1929, p. 386) considers Armiger a distinct genus. Odhner (1929, pp. 20, 21, 30) states his belief that Armiger represents a stage in the evolution of Gyraulus. He found young Gyraulus borealis of two whorls without a stylet on the verge while those of three and one-half whorls had a well-developed stylet. Specimens of Gyraulus laevis of three whorls had a stylet. From these observations he concludes that the develop- ment of the stylet (penisstachel) may be checked in the later fall, possibly through some unfavorable climatic condition. Haas, in a review of this work ( 1930, p. 20) does not fully agree with Odhner, believing that more study should be given the subject before conclusions are made. This is undoubt- edly true, but the subject is one of great interest and dissections should be made of many species at different ages to determine whether the stylet is absent in young and immature Gyraulus. It has been present in all speci- mens personally examined, but these were either full grown or nearly full grown. This group of small snails is highly variable specifically and a number of names have been bestowed upon the variations. Two forms appear dis- tinct enough to rank as species, crista (Linn.), with strong ribs projecting from the shell, and imbricatus (Miiller), in which no ribs project from the shell. Armiger spinulosum (Clessin) is i^robably a race of crista Linn. Another species in eastern Asia has been named annandalei by Germain. The value of recognizing subgenera for these variations may be ques- tioned seriously. In 1922, Dybowski and Grochmalachi erected three sub- genera based on spiny variation in Armiger: Nautiloarmiger, Cristoarmi- ger, and Atropoarmiger (vide Lindholm, 1926, p. 24). There appears to be some variation in the genitalia and also in the radula. Odhner found the formula to be 11-1-11 and 14-1-14 in crista from two localities and the writer obtained the formula 16-1-16 from crista Subfmnilies, Genera, and Subgenera- — Recent and Fossil 79 collected in Poland. These differences may all be individual. The group merits additional anatomical study. (k'nus TAPHIUS H. and A. Adams, 1855 T.ype by original designation Planorbis nndecolus Orb. 1855. Taphius H. and A. Ad.\ms, Genera, II, p. 262. Type Planorbis andecolus Orb. 1870. Taphius D.all, Ann. N. Y. Lye. Nat. Hist., IX, p. 351. Tj'pe Planorbis andecolus (H. and A. Adams, error for Orb.). As subgenus of Planorbis 1883. Taphius Fischer, Man. de Conch., \). 507. Type Planorbis andecolus Orb. As section of Planorbis 1884. Taphius Tryon, S. and S. Conch., Ill, p. 106. Type Planorbis andecolus Orb. As subgenus of Planorbis 1886. Taphius Clessin, Syst. Conch. Cab., XVII. p. 33. Type Planorbis andecolus Orb. As subgenus of Planorbis 1899. Taphius Martens, Biol. Cent. Amer., Moll., p. 396. Mentions Planorbis sub- pronus Martens. As subgenus of Planorbis 1905. Taphius D.\ll, Alaska Moll., p. 81. Type Planorbis andecolus Orb. As sj'nonym of Helisoma 1921. Taphius Germain, Rec. Ind. Mus., XXI, pp. 7, 62. Type Planorbis andecolus Orb. As subgenus of Planorbis 1924. Taphius Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 49, plate 4. Variation of Pla- norbis andecolus Orb. 1930. Taphius H. B. Baker, Oc. Papers, Mus. Zool. Univ. Mich., 210, p. 43. Monotype Planorbis andecolus Orb. As genus 1931. Taphius Thiele, Handbuch, Part 2, p. 479. Type Planorbis andecolus Orb. As .-section of Planorbis Shell (plate 77, figs. 13-15). Sinistral, whorls few, raindly increasing in diameter, the body whorl wide and much enlarged; spire greatly de- pressed below the level of the body whorl, the spire whorls bluntly angu- late; umbilical side flattened; all the whorls visible and nearly in the same plane; aperture large, expanded; no lamellae within the aperture. Animal. The characteristic of the animal and its anatomy have not been described. Geographical Distribution. South and Central America from southern Mexico to Peru and Bolivia. Species Considered as Valid. Only five species are here referred to Taphius. Taphius andecolus (Orb.) Lake Titicaca, Peru Taphius moiitanus (Orb.) Lake Titicaca, Peru Taphius titicacensis (Clessin) Lake Titicaca, Peru Taphius pronus (Martens) Venezuela Taphius s}ibpronus (Martens) Mexico Geological Distribution. Not definitely known. T(tph{}(s pronus has been found fossil in Lake Valencia, Venezuela, probably of Pleistocene age. Remarks. The systematic position of the genus Taphius is greatly in doubt because its anatomy is unknown. Some of the species, as pronus and subpronus, resemble certain species of Tropicorbis and Taphius may be another genus of Planorbidae peculiar to both Central and South America. Typical andecolus bears a striking resemblance to the tyi')ical group of Helisoma and Dall (1905) made Taphius a synonym of that group. Cermain (1921) makes it a subgenus of Planorbis allied to Helisoma. 80 The Molluscan Family Planorbidae Pilsbry (1934, p. 47) associates Taphius with Helisoma and refers Taphius pronus to Helisoma together with caloderma, but pronus certainly does not resemble any form of Helisoma, rather is it allied to Tropicorbis. What the group may be and where it may be placed can only be deter- mined by an anatomical study. With our present limited knowledge, it seems best to regard Taphius as a genus related to Tropicorbis. An excel- lent account of the shell variation of Taphius andecolus, accompanied by a good plate, is given by Pilsbry (1924, p. 49, plate 4). Genus TROPICORBIS Pilsbry and Brown, 1914 Type by original designation, Planorbis liebmanni Dunker (= Pkmurbis orbiculus Morelet) 1880. Gyrorbis Fischer and Crosse, Etudes Moll, terr-fluv. Mex. et Guat., II, p. 70 (non Gyrorbis Fitz., 1833). Example Planorbis orbiculus Morelet. 1884. Menetus Tryon (non H. and A. Adams), S. and S. Conch., iii, ]>. 106. Example Planorbis heloicus Orb. 1899. Planorbula Martens (part), Biol. Cent. Amer., Moll., p. 398. Includes Planorbis obstructus Morelet and Planorbis dcntiens Morelet, now referred to Tro- picorbis. 1899. Menetus M.artens (part) (non H. and A. Adams), o\^. cit., \). 390. Includes species now referred to Tropicorbis. 1914. Tropicorbis Pilsbry and Brown, Proc. Acad. Nat. Sci. Phil., 66, p. 212. Type Planorbis liebmanni Dunker. As section of Planorbis. 1921. Tropicorbis Germain, Rec. Ind. Mus., XXI, p. 91. Type incorrectly given as Planorbis tnaya Morelet. As subgenus of Planorbis. 1923. Tropicorbis Wenz, Fossil. Cat., Pars 22, p. 1627. Genotype Gyrauhis (Tropicor- bis) liebmanni (Dunker). As subgenus of Gyraulus. 1930. Tropicorbis H. B. Baker, Oc. Papers Mus. Zool. Univ. Mich., No. 210, p. 43. Type Planorbis liebmanni Dkr. As genus. 1931. Tropicorbis Thiele, Handbuch, IV, Teil 2, p. 480. Type wrongly stated to be Planorbis maya Morelet. As section of Planorbis. 1934. Tropicorbis Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 52. Type Planorbis liebmanni Dunker. As genus. Anatomy described. 1936. Tropicorbis F. C. Baker, Nautilus, 49, p. 104. Anatomy of Planorbis obstructus Morelet and Planorbis havanensis Orb. described. As genus. 1939. Oh^tructio H.\as. Zool. Ser. Field Mus. Nat. Hist. XXIV, p. 99. Type by original designation Planorbis janeiremsis Clessin. As subgenus of Planorbis. 1940. Tropicorbis F. C. Baker, Nautilus, LIII, p. 106. As genus. 1941. Obstructio Haas, Nautilus, 55, p. 31. Shell. Of medium size, idtradextral, orbicular, of few whorls which may increase regularly in diameter (plate 77, figs. 7-9 orbiculus) or the body whorl may increase rapidly in diameter (plate 77, figs. 10-12, pallidus) ; whorls in view equally on both sides, somewhat overlapping on the left (spire) side; aperture unarmed or with one large parietal lamella with a small infraparietal below it, and four lamellae within the outer lip. The labial lamellae differ principally from those of the genus Planorbula in having the lower palatal lamella pointing slightly downward on the left side while in Planorbula this lamella always points upward, in the group Hcddemanina the upward end forming a vertical and transverse lamella combined. The basal lamella in Planorbula is normally more massive and is, in some species, distinctly curved (plate 76, figs. 7, 8, 9). Sub fcun Hies, Genera, and Suhijeuera- -Recent and Fossil 81 Animal. When in locomotion the foot is rather long and narrow, rounded before and tapering to a point behind. The tentacles are very long and filiform and the eyes are large, black, and conspicuously placed at the inner base of the tentacles (plate 78, figs. 3, 4). The velar area is well developed. When at rest (plate 70, fig. 4, Tropicorhu havanensis) the foot may be hunched up, rounded, and even the tentacles may be drawn back- ward. The Tropicorbis group is noteworthy for the peculiar pigmentation observed in some species, this consisting of dark, blackish or brownish, markings which show plainly through the shell (plate 78, figs. 3, 4, Tropi- corbis nigrilabris (Lutz) ), and are particularly plain when the animal is removed from the shell (plate 12, fig. 5, T. havanensis (Pfr. ) ). These some- times show on the base, through the shell, as dot-like markings (plate 70, fig. 4, T. havanensis). ANATOMICAL CHARACTERISTICS PLATE 12 (Tropicorbis havanensis) GENITALIA. Male Organs (fig. 11) . Seminal vesicle (SV) of greater diameter than the ovisperm duct. It is beset with numerous protuberances or glands many of which have the form of club-shaped diverticula. They vary in size anteriorly, the larger vesicles being nearer the ovotestis. The whole seminal vesicle is about 2 mm. long. The sperm duct is over 5 mm. long and is very narrow. It is peculiarly enlarged at the junction of the oviduct and sperm canal and might be considered a carrefour, but that feature is attached to the female system and is a small swelling into which the albumen duct enters (fig. 11, CF). See figs. 7, 8, CF. The I'jrostate (PRS) is very long (3.5 mm.) and bears about fifty short, sac-like diverticula. These are placed on a separate duct, the prostate duct, the free portion of which is very short and ciuickly joins the vas deferens. A cross section through the prostate (fig. 9, PD, SPD) shows the relation- ship between these two separate ducts. The vas deferens (VD) is moder- ately long (3.5 mm.) and is a small tube throughout its length except that it is slightly enlarged where it enters the vergic sac (fig. 1, VD). The penial complex (fig. 11) is much elongated; the preputium (PR) is cylindrical and slightly longer than the vergic sac ( VS) . In another specimen (fig. 10) the preputium and vergic sac were more nearly equal in length and the upper part of the vergic sac was slightly enlarged. The vergic sac is always of less diameter than the preputium. The retractor muscles (RIVI) are somewhat complicated, there being three branches all con- nected by cross muscles. There are also several small muscles below the retractor muscles which are attached to the mantle and not to the colu- mella muscle. These may be what we have called supporting muscles. There are several series of muscles on the opposite side of the penial complex which we have called supporting muscles (SM). These are attached to the upper j^art of the neck. The upper set, which have small branches, may also help in retracting the penial complex following coitus. Internally (fig. 1) the preputium has two or more pilasters. There is a heavy muscular ring or diaphragm which separates the preputial cavity from the vergic space (fig. 1, D, fig. 2). This apparently takes the place of the papilla in Gyraidiis, but there is no second ring below this ring, as there is in Gyraulus. The verge (V), very long and cylindrical, ends in a 82 The Molluscan Family Planorhidae small papilla and the sperm canal has a central outlet (fig. 3). The walls of the vergic sac are thin but those of the preputium are rather thick. Female Organs. The spermatheca (S) is pear-shaped and less than 1 mm. long. The spemiathecal duct is longer than the spermatheca, very narrow, and enters the short vagina (VG) near the female opening. The uterus (U) is narrow and slightly longer than the spermatheca and its duct. The nidamental gland (NG.) is long and narrow (about 3 mm. long) and of larger diameter than the uterus. The oviduct (OD) is about 2 mm. long and smaller in diameter than the nidamental gland but much wider than the sperm duct. The albumen gland is short, somewhat pear-shaped with large gland cells (fig. 6). It lies over the intestine, one loop of which passes through a trough-like space on the under side of the albumen gland. The junction between the oviduct, sperm duct, and ovisperm duct, together with the albumen gland connections, are shown in figs. 7 and 8. Hermaphrodite Organs. The ovotestis (OT) consists of many club- shaped diverticula placed in a double row. The ovisperm duct is very short between the seminal vesicle and ovotestis but three times this length be- tween the seminal vesicle and the oviduct. The duct is a narrow tube. Two other species of Tropicorbis have been dissected by the writer. Tropicorbis nisei (Dunkerl (plate 13, fig. 9) has twenty-four diverticula on the prostate and Tropicorbis obstructus (]\Iorelet) has eighteen diverticula on its i)rostate. The penial complex is about the same in the three species. Some of the diverticula of the prostate are folded over at the end in riisei (figs. 4, 5). The retractor muscle complex is complicated in riisei but quite simple in obstructus. The spermatheca is rounder and less pyriform in riisei and obstructus and the ducts are longer than in havanensis (compare the figures). In obstructus a number of the diverticula of the ovotestis contained eggs almost ready to be discharged (plate 13, fig. 3). The junc- tion of the prostate duct and the sperm duct to form the vas deferens is shown in fig. 8 iriisei). Pilsbry (1934, p. 53) has figured the genitalia of Tropicorbis pallidus (C. B. Adams), from Bolivar, near Santa Alarta, Colombia. This figure differs in a few respects from the genitalia of riisei, havanensis and obstructus as figured in this volume. There are twelve long and somewhat irregular diverticula on the prostate. The penial complex shows a very long and narrow vergic sac, considerably longer than the preputium. The verge appears as in the other species studied. There is one retractor muscle as in obstructus. It is evident from the knowledge afforded by the four species of which the anatomy is known that there is considerable variation in the details of structure of the genus Tropicorbis. The prostate, particularly, may bear as many as fifty diverticula {havanensis) or as few as twelve diverticula (paUidu.s) . The penial complex may have the vergic sac shorter than the preputium {havanensis) or much longer than the preputium {pallidus). There is complete agreement, however, in the long, narrow verge with tenninal oj^ening, the lobulate seminal vesicle, the long and narrow oviduct, nidamental gland, and sperm duct, and the rounded or pear-shaped spermatheca on a long duct. It is desirable that the genitalia of the type species {orbicidus = liebmanni) be known. It is believed to be like havan- ensis, a related species. Hundreds of shells of orbiculus have been seen but no material containing the animal has been available. Subfamilies, Genera, and Subgenera — Recent and Fossil 83 Respiratory and Renal Systems. The pseiidobranch (of havanensis, plate 12. fig. 4 1 is a thin, leaf-shaped, fleshy organ doubled or folded upon itself. The rectum (Rl lies above the pseiidobranch and has a conspicuous crested ridge extending nearly its whole length, ending some distance above the anus. There is a large pneumostome (PS). In riisei (plate 13, fig. 10) the folded nature of the pseiidobranch is better shown as is also the crested ridge. The crest is present in all species examined. Pilsbry's figure of the pseudobranch of pallidus (1934, p. 53. B» shows a simple folded pouch. In his figure C. the pseudobranch is figured as much elongated. This appears to be a pathologic condition. The kidney (plate 46, fig. 11, riisei) is rather long (about 2.5 mm.), the ureter sharply reflected. A cross section near the middle (fig. 12) shows the kidney to be rounded with the lumen rounded, the two veins being at the lower corners of the section. There is no ridge on the kidney but there is a distinct vertical ridge in the mantle to the left of the kidney. A cross section of the kidney of havanensis (fig. 13) shows that in this species this organ is much more compressed and much wider than in riisei; the central lumen is irregularly oval with the two veins placed below the lumen at the outer ends of the section. Of pallidus, Pilsbry says 'The kidney is long, band-like, and flat, with no trace of a superposed ridge' (p. 52). Digestive System. Stomach region with distinct division into crop, gizzard, and pylons. There is a large blind sac. The intestine makes a backward loop around the liver and extends forward, the rectum ending near the pseudobranch. The digestive organs are alike in all species examined. The buccal sac is pyriform with a large and conspicuous radula sac which protrudes from the posterior end of the buccal sac as a rounded projection. This sac is longer in obstructus than it is in riisei. The salivary glands are cylindrical, longer than the buccal sac. and joined behind, as in other groups of the Planorbinae. The jaw of riisei (plate 50, fig. 12) is composed of three pieces, a wide and low superior part, finely striated along the face, and two lateral pieces which assume the form of a question mark. These are enlarged at their junction with the superior jaw and taper to a point at the lower end. The jaw of obstructus is similar to that of riisei (fig. 11). H. B. Baker has described the jaws of pallidus and kiihnianus (1930, pp. 47, 48). The jaws of Tropicorbis are unlike those of the other genera of Planorbinae (ex- cepting Australorbis) and resemble those of the subfamily Helisomatinae. The radula formula of havanensis (plate 68, fig. 8) is 19-1-19 or 20-1-20 with 109 to 112 rows of teeth. The central tooth has a broad base of attachment and is bicuspid, the cusps spade-shaped and reaching to the lower margin of the base of attachment. Laterals (1-6) squarish with three cusps, the entocone larger than the mesocone and ectocone. The 6th tooth has a small interstitial cusp on the entocone and two very small cusps above the ectocone. The 7th tooth is an intermediate, the entocone broken up into four small cusps and the ectocone with two small cusps on the outer edge above. The 8th to the 16th or 17th teeth are marginals (8, 10, 12), the reflections becoming very long and narrow, with an entocone of four or five small cusps, a single spade-shaped mesocone, and four to six or seven small cusps on the outer edge representing the ectocone. The marginal teeth become narrower toward the edge of the membrane. The outer three marginals are vestigial and are without denticula- tions. The central teeth of the different rows vary in width at the upper 84 The MoUuscan Family Planorbidae part of the tooth. The first thirty-four rows measure 5.4 microns, rows 35 to 89 measure 6 microns and rows 90 to 109 measure 5.4 microns. All central teeth examined exhibited this variation in width. In riisei (plate 68, fig. 6) the formula is 18-1-18 with 105 rows of teeth. The center tooth is like that of havanensis but the cusps do not reach the base of attachment. There are four lateral teeth. The 5th and 6th teeth are intermediate with interstitial cusps between the entocone and ectocone and small cusps above the ectocone (figs. 7, 5, 6). Seven to twelve are typical marginals with a variable number of small cusps, as in havanensis. The 15th to 18th teeth are vestigial. The center teeth vary in width as in havane7isis, but the teeth are somewhat smaller. In obstructus (plate 68, fig. 7) the formula is 19-1-19 and there are 124 rows of teeth. There are seven tricuspid laterals, the 8th tooth is inter- mediate, modified only on the entocone, and there are nine marginals becoming narrower toward the edge of the membrane. The outer marginals are vestigial. The center tooth varies in width as in the other species. H. B. Baker (1930, plate 28, fig. 8) figures the radula of pallidus from Bolivar, Colombia. The formula is 18-1-18 with five laterals and there are 106 rows of teeth. The radula of kiihncrianus is described on page 47 of the same paper. The formula is 19-1-19, with six laterals and 106 rows of teeth. Thus the radulae of five species of Tropicorbis are known; havan- ensis, which is nearest to orbiculus i^licbmanni) , the type of the genus, obstructus, riisei, pallidus, and kiihnerianiis. These cover fairly well the different variations of the species of the genus. The material personally examined is as follows: havanensis. New Orleans. Collected by Dr. E. C. Faust; 10 specimens riisei. Barceloneta, Puerto Rico. Collected by Dr. W. A. Hoffman; 12 specimens obstructus. New Orleans. Collected by Dr. E. C. Faust ; 10 specimens. Geographical Distribution. The genus Tropicorbis is one of the most widespread of any group of American Planorbidae. From Louisiana and Texas in the United States, it extends southward through Mexico and Central America into South America as far south as the Argentine Re- public, a distance of about 7.000 miles. The group is also found in many of the islands of the West Indies. In number of species represented, it out- ranks any other group of the family found in America except Hclisoma, upward of thirty-three species and races being now recognized (see a later page for the list of species). Geological Distribution. Oligocene or Lower Miocene to Recent time. Remarks. The genus Tropicorbis presents some puzzling features of its anatomy which render its systematic position debatable. The nature of the prostate, with many diverticula in a single row, on a separate prostate duct, places the genus in the subfamily Planorbinae. The kidney is also like other members of this subfamily. The penial complex differs from that of Anisus and Gyraulus in lacking a penial stylet. The jaw is quite differ- ent and resembles this organ in Helisomatinae and Planorbulinae. The teeth of the radula also differ in having interstitial cusps on the inter- mediate and marginal teeth. Pilsbry (1934, p. 53) remarks that the group resembles Gyraulus but differs in the unarmed verge and the different jaw and marginal teeth. All points considered, it would seem that its place is with the Planorbinae, the largest number of characteristics agreeing with those of this subfamily. Subfamilies, Genera, and Subgenera — Recent and Fossil 85 Some of tlie species of Tropicorbis have been heretofore placed in the genus Planorbula because of the presence of lamellae within the aperture. These lamellae have the same general position in the two groups but the lower palatal lamella in Planorbula points upward while in Tropicorbis it points slightly downward. The basal lamella is also usually more massive in Planorbula than in Tropicorbis (plate 76, figs. 7, 8, 9). Planorbula, how- ever, has a very different form of genitalia which removes it from the Planorbinae and places it, witii Menctus, in a separate subfamily, PIanorl)ulinae. The relationshij) between the South American Tropicorbis and certain species in Africa is quite remarkable and has been emphasized by Pilsbry (1934, p. 54). Tw^o African species (adowensis and pfcifferi) have been dissected and the genitalia are very similar to the same organs in Tropi- corbis. The African forms may be placed in Afroplanorbis of Thiele, at least, until more is known about other species of the African fauna. This relationship is discussed at greater length under the description of the genus Afroplanoi'bis. \\\u\e the anatomy of the several group forms is similar, there are variations in the shell which seem to warrant a division of the genus into three subgenera or sections. These are indicated below. Subgenus TROPICORBIS SS. Type Planorbis orbiculus Morelet Shell orbicular, the whorls increasing gradually in diameter, the last whorl not notably expanded. Apertural lamellae never present at any stage of growth. Subgenus OBSTRUCTIO Haas, 1939 Type by original designation, Plauorbis jancircnsis Clessin Shell orbicular, whorls increasing slowly in diameter. Aperture with lamellae during some stage of the growth of the shell (plate 76, fig. 7) . Subgenus LATEORBIS F. C. Baker, New Subgenus Type F^lanorbis pallidas C. B. Adams Shell with whorls rapidly increasing in diameter, the body whorl notably enlarged. Aperture never with lamellae. Species Considered as Valid. The species and races believed to group under the three subgenera of Tropicorbis are tabulated below. TROPICORBIS orbiculus (Morelet) may a (Morelet) havaneiisis (Pfeiffer) philipjnanus (Danker) heloicus (Orbigny) tepicensis (Martens) gracilcntus (Gould) peregriniis (Orbigny) chile nsis (Clessin) 77}eridaensis (Preston) bourcardianus (Preston) ce7itimetralis (Liitz) fieldi (Tryon) OBSTRUCTIO jnneiren.sis (Clessin) denticns (Morelet) d('ntie7is ca7i7iarum (Morelet) obstructus (Morelet) ob>itructu>< donbilli (Tristram) obstruct)is auodontus (Pilsbry) dentifcrus (C. B. Adams) deciivis (Tate) paparyensis (F. Baker) nigrilabris (Lutz) albica7is (Pfeiffer) LATEORBIS pallidus (C. B. Adams) nisei (Dunker) straniiiieus (Dunker) pete7iensis (Morelet) isthmicus (Pilsbry) decipie7ii< (C. B. Adams) pedri7ius (Miller) cano7iicus (Cousin) irigyrus (Philippi) 86 The Molluscan Family Plaiwrbidae Genus AFROPLANORBIS Thielc, 1931 Type by original designation Planorbis siidanicus Martens 1885. Mcnetus Westerlund (non H. and A. Adams, 1855), Fauna Palaearc. Reg., V, p. 64. No type cited. As subgenus of Planorbis. 1902. Menetus Westerlund, Rad. Jugoslav. Akad., 151. p. 120. Tvpe Planorbis boissyi P. and M. (non Adams, 1855). 1923. Planorbulina Germain, Rec. Ind. AIus., XXI, p. 179. Citation for Planorbulina Jickeli (1874) Fauna der Land und Siisswasser Mollusk Nord-ost-Afrika. Dresden, p. 221 ('pour la Planorbis alexandrinus Ehrenberg {Segmentina sous- genre Planorbulina)') . 1925. Planorbula Connolly, Trans. Royal Soc. S. Africa, XII, p. 195 (non Haldeman). Anatomy of Planorbis pfeiffcri Krauss. 1931. Ajroplanorbis Thiele, Handbuch, Teil 2, p. 480. Type Planorbis siidaniciLs von Martens. As section of Planorbis. 1934. Ajroplanorbis Pilsbry, Proc. Phil. Acad. Nat. Sci., 86, p. 55. Type Planorbis sudanicus von Martens. 1936. Ajroplanorbis Ha.\s, Abh. Sencken. Natur. Gesell., No. 431, p. 25. Type Planorbis sudanicus von Martens. As genus. 1939. Planorbulina Haas. Malac. Notes, Field Mus. N. H., Zool., XXIV, p. 100. Cita- tion from Jickeli 1874, Nova Acta Acad. Leop. Carol., XXXVII, p. 221. 1939. Biomphalaria Connolly (part); Ann. South African Mus., XXXIII, part 1, p. 483. 1940. Planorbulina H.\as, Nautilus, p. 33. States that citations from Jickeli's paper (1874) are erroneous, there being no reference to this name in the work mentioned, the name used being Planorbula. Planorbulina was used by tl'Orbigny in 1826 in Foraminifera. Shell (plate 81, figs. 2, 3). Small to medium size, orbicular, of few or many whorls which may be closely coiled or rapidly increase in diameter; usually flattened on both sides; aperture rounded, usually in the same plane as the last whorl, lips sharp, the aperture with or without lamellae. Animal. Not observed. ANATOMICAL CHARACTERISTICS PLATE 71 GENITALIA. Male Organs (fig. 9, Ajroplanorbis pfeifferi (Krauss) ). Seminal vesicle occupying about half the length of the ovisperm duct, the glandular follicles short and projecting from the side of the duct. Sperm duct a narrow tube about as long as the ovisperm duct and seminal vesicle combined. Prostate short, composed of five main branches each of which branch again two to four times, thirteen diverticula showing at the upper or outer end of the prostate. From the figure the diverticula appear to be arranged in fan-like manner. There is but one series of diverticula but there is no indication of a separate prostate duct. The vas deferens is a long, fine duct, apparently as long as the sperm duct and ovisperm duct combined. The penial complex has a sac-like preputium with a narrow retractor muscle attached to the summit near the junction of preputium and vergic sac. The vergic sac is a narrow tube, not much greater in diameter than the vas deferens. It is about as long as the preputium and appears from the figure to be slightly enlarged at the end. The features of the interior of the penial complex are neither figured nor described. Female Organs. The spermatheca is an elongated pouch connected with the rather long vagina by a duct half as long as the spermatheca. The Subfamilies, Genera, and Subgenera — Recent and Fossil 87 uterus swells behind the vagina to more than twice the diameter of the vagina. The nidamental gland is about as long as the uterus and is swollen to twice the diameter of the uterus. The oviduct is shorter than the uterus and rapidly narrows to meet the sperm duct. The albumen gland is a large, elongate-ovate organ, half as high as long. Hermaphrodite Organs. Ovotestis apparently a double series of club- shaped diverticula. The ovisperm duct is very narrow and its free por- tion is about as long as the sperm duct. The seminal vesicle is placed nearer the ovotestis than observed in the species of Tropicorbis examined. Pilsl)ry's figures of Planorbis adowensis Bourguignat (plate 71, figs. 10-12) are essentially the same in general generic characters as in pjeifferi described above. The prostate (fig. 10) shows about sixteen short divertic- ula which are unbranched. The penial complex (fig. 11) shows a wide, sac- like preputium and a slender vergic sac equal in length to the preputium. The retractor muscle is inserted at the junction of vergic sac and pre- putium. Internally (fig. 12) the preputium has three vertical pilasters and the verge is very long and slender. The spermatheca (fig. 10) is more pyriform than that of pfcifferi and the duct is longer. The pseudobranch of Planorbis pfcifferi (fig. 7) appears to be folded as it is in Tropicorbis. The figure of the digestive system (fig. 8) shows a wide gizzard, a narrow and elongated pyloris, a narrow blind sac, and the intes- tine looped about the stomach. The salivary glands form a short loop behind the buccal sac. The above anatomical notes are drawn from the papers of Connolly (1925) andPilsbry (1934). Geographical Distribution. Afroplanorbis appears to be distributed over northern and central Africa and to include a number of species. Species Considered as Valid. The following are the species believed to be referable to Afroplanorbis. Other species may be added when their anatomy becomes known. Afroplanorbis sudanicus (von Martens) Afroplanorbis sudanicus tanganikanus Afroplanorbis pfcifferi (Krauss) (Bourg.) Afroplanorbis alexandriensis (Ebrenb.) Afroplanorbis bridouxianus (Bourg.) Afroplanorbis boissyi (Pot. and Mich.) Afroplanorbis adowensis (Bourg.) Afrdjihniorbi.'^ salinariDu (Morelet) Afroplanorbis paetcli (Jickeli) Geological Distribution. Not ascertained. The group is probably as old as Tropicorbis. Remarks. The anatomy of Afroplanorbis sudanicus (von Martens) is unknown, but the shell so closely resembles that of Afroplanorbis adowensis (Bourg.) that they appear to be congeneric. Pilsbry (1934, p. 54) calls at- tention to the similarity of the shells. He also dissected Planorbis adowensis (his figures are copied on my plate 71) and found the anatomy to be very much like that of Tropicorbis. Connolly (1925, plate 8) figures the genitalia of Planorbis pfcifferi Krauss and his figure differs little from that of Pilsbry except in specific details. The branched diverticula of the prostate are believed to be attributed to faulty drawing rather than to real differ- ences in structure. The chief difference between Tropicorbis and Afropla- norbis appears to be in the longer seminal vesicle of the latter, the smaller number of prostate diverticula, the greater size of the uterus and nida- mental gland, and the greater difference in diameter between the preputium and vergic sac. 88 The MoUuscan Family Planorhidae The African group would appear properly to take the name Afropla- norbis proposed by Thiele, preferably as a genus closely related to Tropicorbis. It has no relationship with Planorbula Haldeman which is purely an American genus belonging to a different subfamily. The close relationship between Tropicorbis of Central and South America and the African species here referred to Ajroplanorbis is, as pointed out by Pilsbry (1934, p. 55), an interesting parallel in zoogeography. A similar relation- ship is found in the Ancylidae and in some groups of land shells. In a recent work (1939, p. 483) Connolly uses the generic name Biomphalaria Preston for all of the African species once referred to Pla- norbula. However, the anatomy of the type of this genus, smithi Preston, is unknown and until that species has been examined anatomically it would seem unwise to use this name so inclusively. Should the anatomy jirove to be like that of the two species here referred to the genus Ajro- planorbis, Planorbis adowensis and P. pfeifferi, it would then take prece- dence over Ajroplanorbis which would become a synonym of Biomphalaria. Tropicorbis appears to be generically distinct from the African species and can not be included in either Ajroplanorbis or Biomphalaria, as suggested by Connolly (p. 484j. Genus SYRIOPLAXORBIS F. C. Baker New name for HETF]RODISCUS Westerlund, preoccupied. Type Planorbis libanicus Westerlund, originally designated for HETERODISCUS 1902. Hetcrodiscus Westerluxd, Rad. Jugoslav. Akad., 151, p. 120. Tj'pe Planorbis libanicus Westerlund. As subgenus of Planorbis. Non Heterodiscus Sharp, Insecta, 1886. 1905. Heterodiscus Dall, Alaska Moll., p. 83. Type Planorbis libanicus Westerlund, As section of Planorbis. 1931. Heterodiscus Thiele, Handbuch, Teil 2, p. 479. Type Planorbis libanicus Wester- lund. As section of Planorbis. 'Shell n: t. media (d. 14 mm.), supra late profundeque concavo-umbilicata, subtus subplana, sub lente distincte sitiraliter lineata. spira magna, utrinquc orbiter subaeciua, anfr. 5-6, primi lenti, ultimus subcvlindraceus (typ. PI. libanicus W.).' Westerlund, p. 120. Original description of Planorbis libanicus Westerlund: 'Testa magnitudine medi- ocris, supra late profundeque concavo-umbilicata, infra subplana, nitida, cornea (subtus paullo pallidior), firma, laevigata, sub lente forti densissime at distincte spiraliter lineata ; anfr. 5^2-6, convexi, interiores utrinque perlente accrescentes, spiram magnum, subaequalem formantes, ultimus major, rotundatus, subcylindraceus, supra convexus, subtus pone suturam impressam obtusissime angulatus, extrorsum paullo planulatus; apertura oblique rotundato-lunaris, marginibus distantibus, disjunctis, basali oblique surrecto. Diam. 14, alt. ad apert. 5 mm. 'Hab. Mons Libanon (legit beat. Evers, Havniensis). 'Haec species forte typum novi subgeneris format, quod a subgen. Meneto differre A'idetur; Testa supra late concavo-umbilicata, infra subplana, sub lente tenue distincte spiraliter lineata, spira magna, utrinque subaeque lata.' Westerlund, Nach. Deutsch. Malak. GeselL, 1899, pp. 170-171. Remarks. All of the information concerning this group name and its type species is given above. No specimens for figuring have been obtain- able and no figure has been published, as far as known to the writer. Westerlund mentions in the description of the species (libanicus) that it differs from the subgenus Menetus and that it should become the type of a new subgenus, which he later calls Heterodiscus, which is unfortunately preoccupied. SubjainUies, Genera, and Subgenera — Recent and Fossil 89 In Westerlund's list of the subgenera of Planorbis (1902, p. 120), the type of Menetus is given as Planorbis boissyi P. and M., which is now placed in the genus Afroplanorbis, the type of Menetus being Planorbis opercidaris Gould. The comparison of Heterodiscus with Menetus would indicate that the latter group was somewhat related to the African species and the Latin description would fit, in a measure, some species, as adowensis and suflanicus. The habitat of Planorbis libanicus is not so far removed from the African region as to preclude the possibility that this species might group with Afroplanorbis, hence the new name Syrioplanorbis (Heterodiscus) would become a synonym of Afroplanorbis. Only an ex- amination of the animal of libanicus would positively settle this question. Species Considered as Valid. Sijrioplanorbis libanicus (Westerlund) is the only species attributable to this genus and, as indicated above, the \'alidity of the generic concei:»t is not wholly certain. Genus BIOMPHALARIA Preston, 1910 Type by original designation Biomphalaria S)7iithi Preston 1901. Plnnorhia J. E. S. Moore, To the Mountains of the Moon, p. 260. Monotype Planana albertensis J. E. S. Moore (non Planarin Brown, 1827, or Miiller, 1776). 1910. Biomphalarin Preston, Ann. Mag. N. H. (8), VI, p. 535, plate ix, figs. 26, 26a. Tyjie Biomphalaria smithi Preston. As genus. 1927. Planaria Pilsbry and Bequaert, Bull. Amer. Mus. N. H., LIII, p. 121. Monotype Planaria albertensis J. E. S. Moore. 1927. Biomphalaria Pilsbry and Bequ.\ert, op. cit., p. 115. Monotype Biomphalaria smithi Preston. As .synonym of Planorbis Miiller. 1931. Biomphalaria Thiele, Handbuch, Teil 2, p. 479. As section of genus Planorbis. Tvpe wrongly given as Planorbis choanomphalus von Martens. 1934. Biomphalaria Pilsbry, Proc. Phil. Acad. Nat. Sci., 86, p. 55. Type Biomphalaria smithi Preston. 1936. Biomphalaria Ha.a.s, Abh. Secken. Natur. Ge.sell., No. 431, p. 25. Type Biom- phalaria smithi Preston. As genus. Shell (plate 81, fig. 4). Subdiscoidal, planulate with concave spire, last whorl very large; umbilicus open, but shallow; aperture gaping; labrum greatly receding below (Preston). The .shell is ultradextral. Of this species Pilsbry says (1927, p. 120) 'The prominent character of this species is the deviation towards the left of the last half-whorl.' Viewed as a dextral species, the last part of the whorl drops below the periphery as in some specimens of Gyraidus defiectus. Animal. The anatomy of the group is at present unknown. Geographical Distribution. Lake Albert Edward, Belgian Congo, Africa. Only the type species is known. Planorbis ruppelli Dunker, Pla- norbis choanomphalus Martens and Planorbis katangae Haas, included in this genus by Haas (1936) appear to belong elsewhere. They do not have the characteristics assigned to Biomphalaria. Species Considered as Valid. Biomphalaria smithi Preston is the sole representative of the genus here recognized. Remarks. This genus is unknown anatomically and its true position in planorbid nomenclature can not be definitely assigned until the animal has been dissected. Pilsbry ( 1927, p. 120) suggests that it is a modification of the Planorbis adoiuensis type and might be placed in the same section of 90 The Molhiscan Family Planorbidae the genus Planorbis. In a later publication (1934, p. 55) this relationship is again emphasized. In both references by Pilsbry the suggestion is made that the shell might have been modified somewhat after the manner of Taphius. The shells as figured by Pilsbry (1927, p. 121, reproduced on plate 81 of this work) are strongly suggestive of Taphius, and Biomphalaria might bear the same relationship to Ajroplanorhis that Taphius bears to Tropicorbis. Its best place in classification at present appears to be near Afroplanorbis as a distinct genus. Genus AUSTRALORBIS Pilsbry, 1934 Type by original designation Planorbis guadaloupensis Sowb. = Planorbis glabratus Say 1883. Menetus Flscher, Man. de Conch., p. 509. Type PI. guadaloupensis Sowb. (non H. and A. Adams, 1855). As section of Planorbis 1899. Menetus Martens, Biol. Cent. Amer., Moll., p. 390 (non H. and A. Adams, 1855). Martens gives no type but says subgenus is peculiar to South America and mentions Planorbis cumingia7ius Dkr., and Planorbis guadaloupensis Sowb. as examples 1905. Planorbina Dall, Alaska Moll., pp. 81, 84. Type by original designation P/a«or£)is olivaceus Spix (non Planorbina Haldeman, 1843). As section of Planorbis 1918. Planorbina Walker, Miscel. Pub. Mus. Zool., Univ. Mich., Xo. 6, pp. 11, 94. Type Planorbis olivaceus Spix (non Planorbina Hald, 1843). As section of Planorbis 1921. Planorbina Germain, Rec. Ind. Mus., XXI, pp. 6, 41. Type Planorbis guadalou- pensis Sowb. (non Planorbina Haldeman, 1843). As subgenus of Planorbis 1923. Planorbina Wenz, Fossil. Cat., pars 22, p. 1482. Genotype Planorbis guadalou- pensis Sowb. (non Planorbina Haldeman, 1843). As genus and subgenus 1930. Planorbina H. B. Baker, Oc. Papers, Mus. Zool., Univ. Mich., No. 210, p. 43. Type Planorbis olivaceus Spix (non Planorbina Haldeman, 1843). As genus 1931. Planorbina Thiele, Handbuch, Teil 2, p. 480. Type Planorbis olivaceus Spix (non Planorbina Haldeman, 1843). As section of Planorbis 1934. Australorbis Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 55. Type Plaiiorbis guadaloupensis Sowh. (^ Planorbis glabratus Say). As genus 1938. Australorbis Martins, Contribuicao ao estudo do genero Australorbis Pilsbry, 1934. On p. 47 lists Brazilian species of this and other genera. Some of the species listed belong to Tropicorbis 1940. Australorbis Scott, Xotulae Naturae, No. 54, p. 9. As genus. Shell (plate 77, figs. 29-31, Australorbis glabratus (Say) ). Large, bi- concave, smoothish, of slowly widening whorls which are rounded or angular laterally (Pilsbry, p. 55). The shell is sinistral. Animal. Resembling Tropicorbis in general form. The color is grayish or blackish, the mantle mottled with brown or cinnamon. ANATOMICAL CHARACTERISTICS PLATE 9 {Australorbis glabratus) GENITALIA. Male Organs (fig. 10) . The seminal vesicle (SV) is 3 mm. long and is an enlargement of the ovisperm duct on which there are many elongated follicles placed laterally. For a distance of 2 mm. behind and 4 mm. in front of the seminal vesicle there are numerous nodes which are probably continuations of the seminal vesicle. The sperm duct (SPD) is a very long and narrow tube (29 mm. long) of the same caliber throughout. The prostate is 8 mm. long and is composed of twenty-three or twenty-four diverticula, the two or three anterior diverticula single and unbranched and the three posterior diverticula bifurcate. The others, eighteen in num- Subjnniilies, Genera, and Subgenera — Recent and Fossil 91 ber, Inwc three iiiaiii l)ranches from a single stem, each branch again dividing two or three times, the secondary diverticula being of unequal length. All diverticula arise from the sperm duct in a single series, not in nudtiple series, as in Helisoma. A single branched diverticulum is shown in fig. 6. The diverticulum enters the sperm duct directly and is not placed on a separate duct as in Tropicorbis. The vas deferens (VD) is a narrow tube about 10 mm. long, of less diameter than the sperm duct. The i)enial comj^jlcx (fig. 10) consists of an elongated, cylindrical, sac- like preputium (PR) , about 4 mm. long and 0.7 mm. wide and of about the same diameter throughout its length. The very narrow vergic sac (VS) is 3 mm. long or slightly shorter than the preputium. It is not much greater in diameter than the vas deferens. There is a rounded enlargement of the vergic sac at the end receiving the vas deferens. There are several sets of muscles. A wide retractor muscle (RM) comi^osed of several smaller branches, is attached to the ui:)per part of the preputium and to the colu- mellar nmscle. On the same side of the preputium there is a wide muscle about midway of its length and two smaller muscles near the male open- ing which appear to be supporting muscles since they are attached to the mantle above the penial complex. On the opposite side of the preputium there is a narrow muscle attached to the upper part near the insertion of the vergic sac, and a very wide muscle or set of small muscles which are attached to the roof of the mantle cavity and are presumed to be support- ing muscles (SM). Some of these may aid in retracting the I'jcnial complex after coitus. Internally (fig. 9) there are two wide, heavy pilasters in the preputium tapering to a point at the upper part of the preputial space. The space between the pilasters is marked by many cross muscles forming a reticu- lated pattern (PL). There is a flattened muscular ring or diaphragm (D). The verge (V) is long and very narrow. It tapers to a point and the sperm canal is placed at the center (fig. 5). There is no penial papilla. Female Organs. The spermatheca is pear-shaped (S) and the duct (SD) is narrow and as long as the spermatheca. Both gland and duct measure a trifle more than 3 mm. in length. The vagina (VG) is very short and wide. The uterus is the same width as the vagina and gradually en- larges in diameter to meet the nidamental gland (NG) which is very long and wide (about 8 mm. long, 1.5 mm. wide). A part of the uterus projects behind the nidamental gland for several millimeters. The oviduct (OD) is a narrow tube extending from the ovisperm duct backward. It is about twice the diameter of the sperm duct and is about 18 mm. in length. There is a rounded carrefour (OF) extending from the oviduct to which the duct of the albumen gland is attached. The albumen gland (fig. 8) is rectangular in form and is composed of large follicles. The space for the passage of the intestine (IX) is quite conspicuous. Hermaphrodite Organs. The ovisperm duct (SO) is very long (17 mm.) and is a simple tube except for the portion occupied by the seminal vesicle. The ovotestis is composed of multiple diverticula as seen in situ (fig. 10, OT). In cross section (fig. 4) the ovotestis appears to consist of a main diverticulum (fig. 1) upon which a number of short divertictila are attached (2). The organ is not multiple in the same sense that Helisoma is, which is observed to be fan-shaped in section. Several of the diverticula contained one large ovum ready for exi)ulsi()n. 92 The Molluscan Family Planorhidae The above description agrees substantially with that of Pilsbry (1934, p. 55). The spermathecal duct in the specimens examined was not short, as Pilsbry found it, and, therefore, the spermatheca was not really adnate. The vergic sac, also, is almost as long as the preputium in the specimens examined. With these exceptions the genitalia of glabratus {guadalou- pensis) here figured are like the figures of the race christopherensis given by Pilsbry on page 57. The figure by Scott (1940, p. 10) agrees with the specimens personally dissected, especially in the form of the spermatheca. Respiratory and Renal Systems. The pseudobranch is rather long and rounded. A frilled crest or ridge extends down the center of the rectum (R) which it crosses as a simple ridge to the anal opening (A) and extends across the pseudobranch to the lower edge. There is a large pneumo- stome (PS). The kidney (plate 45, fig. 1) is long and narrow (16 mm. long, 2.5 mm. wide). The ureter is nearly 2 mm. long and is a narrow tube directed upward at a right angle from the kidney. The veins are very large. The pericardium is 3 mm. long and 2 ram. wide. A low, wide ridge extends from below the pericardium to the lower end of the kidney. Cross sections show several .interesting features. The position of each section is shown at A, B, C, D, E, in fig. 1. Section E (fig. 7) through the pericardium shows a large lumen nearly filling the entire section, con- taining many glandular diverticula. There are no veins. In section D (fig. 8) the lumen is smaller, rather squarish in shape, with the pulmonary vein (AP), large and round, on one side and the renal vein (RA), smaller and oviform, on the other side. The low ridge is seen at the left. In section C (fig. 9) the lumen is somewhat smaller and there is the same disparity in size between the two veins. The ridge (RK), though wide, is higher than in section D. In section B (fig. 10) the lumen is much smaller, the veins still disproportionate in size and the ridge very wide, but low, and pro- jecting over the left margin. In section A (fig. 11) near the base of the kidney, the whole organ is seen to be flattened, the lumen very small, the veins flattened, more nearly equal, and the ridge wide, flattened, and pro- jecting over the left margin. The form of the long ridge to the left of the kidney is shown at the left in this section (RD). The ridge is a very characteristic feature in the kidney of Australorbis . Digestive System. The stomach region (plate 48, figs. 9, 10) resembles that of Promenetus, the gizzard rather rounded, not flattened, the pyloris long and the blind sac rather short and placed as in Helisoma. The intes- tine makes a loop around the stomach and another looji around the liver, then runs forward to the rectum which bears a plaited crest or ridge (plate 48, fig. 9). The buccal sac is short and high, not much elongated. The radula sac or pouch is large and rounded, somewhat as in Tropicorbis. The salivary glands are narrow and nearly three times as long as the buccal sac. They are joined behind as in Helisoma. Jaws three in number as in Tropicorbis (plate 50, fig. 13). The superior jaw is very high, the length being about three times the height. It is finely striated on its anterior face. The side jaws are much shorter than the width of the superior jaw and are very narrow. The side jaws are shorter in comparison with the length of the superior jaw than in most species Subjar/illies, Genera, and Subgenera— Recent and Fossil 93 of Planorbidae. The figure on plate 50 agrees with that by Pilsbry (1934, p. 57). The raclula formiUa is 31-1-31 to 33-1-33 with 182 rows of teeth (plate 68, fig. 5) . The center tooth (60) is wider than high, the lower outer corners of the base of attachment expanded to the extent that the base is twice as wide as the summit of the tooth. There are two sharp, spade-shaped cusps which extend below the lower margin of the base of attachment. Lateral teeth (1-13) asymmetrical, tricuspid, the cusps sharp, subequal, and extending below the base of attachment. The intermediate teeth (14-15) differ from the lateral teeth in having either an extra interstitial cusp between the ectocone and mesocone (14) or an interstitial cusp as in 14 and an extra cusp above the ectocone. Marginal teeth ( 16-26) elongated, oblique, the mesocone remaining a large sharp cusp, but the entocone splitting into three to five small, subequal cusps arranged obliquely. The ectocone continues as a large cusp but above it, on the' margin of the tooth, there are three to six very small cusps in addition. The ectocone is always separated from the mesocone by a distinct gap. The small cusps above the ectocone are placed higher up on the tooth than in other genera. The outer marginals are very narrow and oblique and the cusps appear as minute serrations. Even here, however, the two groups of cusps, mesocone and ectocone, are separated by a considerable space. Pilsbry (1934, p. 55) figures the radula of the race christopherensis which agrees in all essential details with the figures on plate 68. He gives the formula as 30-1-30 with seventeen laterals. In specimens personally dissected the marginals began on the 16th tooth in two specimens and on the 18th tooth in one specimen, the 15th to 17th teeth being intermediate in character. These differences are unimportant. Scott (1940, pp. 10-12) figures the radula of specimens from Caracas, Venezuela, and Puerto Rico, showing great variation in the form of the cusps. The Venezuela form with a formula of 45-1-45 may be represen- tative of the race oUvaceus. The material used for this anatomical study was received from Dr. Wm. A. Hoffman and was collected at Lares, Puerto Rico. Geographical Distribution. Except for its occurrence in Haiti, Puerto Rico, and the Caribbean islands, Avstrcdorbis is a South American group (Pilsbry I. It is known in South America from Venezuela southward to Argentine Republic. Species Considered as Valid. ]\Iany names have been given to varia- tions within this genus and consequently there are many synonyms. The following species and races appear to be recognizable: Australnrbifi ginbratus (Say) (= Quadaloupensis Sowh.) Australorbis glabratus christ ophcren.fis Pilsbry Australorbis glabratus oUi'accus (Spix and Wagner) Australorbis glabratus refulgcns (Diinker) Australorbis glabratus higubris (Wagner) Australorbis glabratus blauncri (Germain) Australorbis antigucnsis (Sowerby) A ustralorbis itn 7)i unis ( Liit z ) Australorbis bahiensis (Diinker) Australorbis tenagophilus (Orbigm-) Geological Distribution. This genus probably dates fi'om the Oligocene or Miocene period of the "West Indies and South America. 94 The Molluscan Family Planorhidae Remarks. Australorhis is so peculiar in certain of its anatomical char- acteristics as to puzzle the systematist regarding its proper position in the classification of the family Planorbiclae. In its narrow penial complex with- out penial gland it is related to Tropicorbis. The prostate, however, is very different from any member of the Planorbinae and superficially resembles some of the Helisomatinae in the presence of multiform diverticula. The ovotestis is also of a multiform nature. The prostate diverticula are also attached directly to the sperm duct instead of to a separate prostate duct as is the case in Tropicorbis. In this respect, the prostate of Australorbis resembles that of the genus Drepanotrema, the few diverticula in this group being attached directly to the sperm duct. The kidney is of the Helisoma type, with a distinct ridge. In spite of the multiple nature of the diverticula of the prostate and ovotestis, the group appears to be related to Tropicorbis and to be correctly placed in the subfamily Planorbinae. The absence of a penial gland re- moves it from Helisomatinae and Planorbulinae and the absence of a flagellum, and also the form of the shell (with overlapping whorls), ex- cludes it from the subfamily Segmentininae. When the characteristics of the prostate are closely examined it is seen to be uniserial in form in spite of the branched nature of the diverticula. Each diverticulum arises from the sperm duct as a single tube, the branching taking place after the diverticula are above the sperm duct. So also in the ovotestis, each divertic- ulum arises from the ovisperm duct as a single tube, the branching being on one side only. In the Helisomatinae, both the prostate and the ovotestis have the diverticula radiating from the ducts like the spokes of a wheel, in fan- formation. The ridged kidney is an exception in the Planorbinae. This characteristic, as well as the apparent multiple appearance of the prostate and ovotestis, may show ancient affinities with the Helisomatinae. Austra- lorbis is apparently an aberrent genus of the family. Pilsbry has suggested (1934, p. 56) that it might be considered a sub- genus of Tropicorbis but this procedure would appear untenable because of the peculiar prostate and ovotestis as well as the ridge on the kidney. Pilsbry did not examine the ovotestis or the kidney. The name Planorbina Haldeman was used for this group by Dall in 1905, the Brazilian species Planorbis olivaceus Spix and Wagner being designated as the type. Germain, in 1921, selected Planorbis guadaloupensis Sowb., as type of Planorbina. But as Pilsbry states in his description of Australorbis, neither olivaceus nor guadaloupensis answer to Haldeman's description 'whorls numerous, nearly equal,' the whorls in these species increasing in diameter to such an extent that the last whorl is notably wider than the preceding whorl. Haldeman's Planorbina is now considered a synonym of Anisus. Pilsbry 's discussion of the reasons for rejecting the types proposed for Planorbina, for which no type was designated by Haldeman, by Dall or Germain are well stated and do not need to be repeated here. Genus ANISOPSIS Sandberger. 1875 Type herein nominated Planorbis calculus Sandberger 1875. Anisop.sis Sandberger, Land imd Slissw. Conch, der Vorwelt, p. 958. No type cited 1905. Anisopsis Dall, Alaska Moll., p. 81. Plaiwrbis loryi Coq., and Planorbis cal- culus Sandb. cited as examples Subfamilies, Genera, and Subgenera — Recent and Fossil 95 Shell (of Anisopsis ccdcidus (Sandberger) , plate 81, fig. 10 ». 'Testa cal- culiforinis, superne excavata, inferne latissime uinbilicata. Anfractus 3^/4, gracilis, quadrangulates, superne excavati, ad margineuni sui)erum necnon ad iimbilicuin carina cincta, suturis tenuibus profundis disjiincti, costulis trans versalibus subtilibiis ornati, ultimus permagnus, spiram eminens (Sandberger, p. 14). Taf. 1, fig. 7, 7a (stark vergrossert).' The shell is ultradextral, with a distinct, sharp carina in the middle of the whorls on the right side. The left side also has carinated whorls. The whorls are few in number, increasing rather rapidly in diameter. From the figures there appears to be a carina at the periphery. Horizon and Distribution. Middle or brown Jurassic period. Cajac, in layers e and f. Very rare. Remarks. The name Anisopsis appears to be a nude name, no type hav- ing been formally designated for it, as far as the writer is aware. It also appears to have been comparatively unnoticed by recent students of the Mollusca. The only American reference observed is that by Dall in 1905, who cites Planorbis loryi Coq., and Planorbis calculus Sandb. as examples. The original reference is in a stratigraphic table on page 958 of Sandberger's work in which Anisopsis appears between Bathyomphalus and Anisus. The only valid reason for associating the two species mentioned above with Anisopsis is the presence of the stars in the Aliddle ( ]\Iittlerer) Jura and the Upper (Oberer) Jura in the table, indicating that these two species are the ones intended for this group name, since no others from these horizons occur in the body of this work. Planorbis calculus Sandberger occurs first on page 14 and should be taken as the type of Anisopsis. On page 15 Sandberger mentions the like- ness of this sj^ecies to the tricarinate Valvatas of North America typified by Valvata tricarinata. The figure of this species does look much like Valvata tricarinata on the right side but on the left side the figure is too wide, lacking the distinct carina and deep umbilicus of the American Valvata. Dall (1905, p. 81) suggests its relationship to Helisoma but the left side is different from any species of that genus known. The exact size is not given by Sandberger, who states that the figure is much enlarged. The second species, Planorbis loryi Coquand (Sandberger, p. 41) is more planorboid in form and somewhat different in shape from calculus (see plate 81, fig. 11). It is also larger. Sandberger suggests its resemblance to Planorbis complanatus (Linn.) (=jontanus Lightfoot) and Planorbis carinatus Miiller, but the figures do not resemble either of these species. Sandberger's description of this species is as follows: 'Testa calculiformis, su])ernc profunde excavata, inferne depressa, latissime umbilicata. An- fractus quinque. gracilis, costulis transversalibus tenuibus muniti et carinis duabus acutis insignes, prima partem su})eram excavatam, altera basin cingente. Apertura trapezoidea, valde iniquilateralis.' The horizon and localities for this species are given as follows by Sandberger (p. 41) : 'Villers le Lac (physaschicht b), les Rousses, Charix bei Nantuar, Alferme und Vigneules am Bieler See in den gleichen Schich- ten.' These localities are in the Upper or White Jura. The group Anisopsis, which may be designated as a genus of the sub- family Planorbinae, may be retained to contain these early fossil species. The two species referred to this genus may not be congeneric, loryi appear- 96 The MoUuscan Family Planorhidae ing more like some of the species of Planorbis or Anisus. IVIany of the names of groups of the Planorbidae have been used rather loosely by European writers. Sandberger, for example, lists the subgenera Menetus, Helisoma, and Carinifex among the European fossils, groups which we now know are confined to America and have no representatives outside the Western Hemisphere. All of the extinct Planorbidae, both American and European, are badly in need of a thorough taxonomic revision. Species Considered as Valid. Anisopsis calculus (Sandberger). the genotype, is the only sj^ccies unciucstionably assigned here. The assignment of Planorbis loryi Cociuand seems indefensible. Subfamily SEGMEXTININAE F. C. Baker, New The prostate diverticula are simple sacs placed in a single row along a prostate duct as in the subfamily Planorbinae. The penial complex has one or two flagella placed at the end of the vergic sac and in addition sev- eral genera have a penial gland in the preputium. The jaw is fragmented as in Planorbinae. The radula teeth are modified by additional cusps or by the presence of many interstitial cusps. The kidney is without a ridge. Type genus Segmentina Fleming. The groups included in this subfamily are as follows: With penial gland but without duct: Segmentina, Hippeutis, Pingiella. With penial gland and an external duct: Intha. Without penial gland: Polypylis, Drepnnotrema, Acrorbis. With long flagella: Pingiella, Polypylis, Intha. With short flagella: Scgme7itina, Hippeutis, Acrorbis. With both long and short flagella: Drepanotrema. With lamellae or barriers within the aperture: Segmentina, Polypylis, Trochorbis. Without lamellae or barriers within the aperture: Hippeutis, Helicorbis, Pingia, Intha, Drepanotrema, Platytajyhiu.-^. Acrorbis. Several groups have not been examined anatomically and their position is doubtful. Such are Helicorbis, Trochorbis, and Platijtophius. The fossil group Paraplatiorbis must, of course, be placed by shell characters alone. Genus SEGMENTINA Fleming, 1817 Monotype Xautilus lacustris Lightioot ^^ Planorbis nitidus O. F. Miiller 1817. Segmentina Fleming, Edinburgh Encyclopedia. Conchology, ed. VII, Vol. XII. Monotype, Nautilus lacustris Lightfoot = Planorbis nitidus O. F. Miiller 1818. Segmentina Fleming, Supplement to 4-6th ed. Encyc. Brit., Ill, 'Conchology,' p. 309. Type Nautilus lacustris Lightfoot 1819. Hemithalamus Le.ach, Moll. Brit. Synop. (proofs), p. 137 1831. Hemithalamus 'Leach' Turton, Man. Land Fresh-water Shells Brit. Isl., p. 116. In synonymy of Segmeyitina nitida 0. F. Miiller 1833. Hemithalamus Fitzinger, Syst. Verz, p. 110 1840. Segmentaria Sw.\inson, Treat. Malac, p. 337. Lapsus for Segmentina. As sub- genus of Planorbis 1842. Segmentina H.'\ldem.\n, Mon. Fresh-water Univ. Moll., U. S., p. 14. No type cited. As subgenus of Planorbis 1847. Segmentina Gr.ay. Proc. Zool. Soc, p. 509. Type Nautilus lacustris Lightfoot. As genus 1847. Discus Gray, Proc. Zool. Soc, p. 509. No type cited. As synonym of Seg- 7)ienti7ia 1850. Segmentina (part) Stein, Schnecken u. Musch. Berlins, p. 78. Segmentina x Hippeutis A Subfamilies, Genera, and Subgenera — Recent and Fossil 97 1855. SegmcHti)ia Moquin-Tandon, Hist. Moll. Terr. Fluv. France, II, pp. 423, 424. Typo Planorbis nitidus Miiller. As genus 1865. Scgmentina Binney, L. and F-W. Shells N. A., II, p. 136. No type cited. As genus 1867. Appendicular id (])art) Ficinus, Zeits. fiir gesamm. Naturw., XXX, p. 363 1870. Segmcntina D.'VLL, Ann. N. Y. Lye. N. H., IX, p. 352. Type Planorbis lacustris Lightfoot. As genus 1883. Segmenlina Fi.scher, Man. de Conch., p. 509. T.ype Planorbis nitidus Mi'ill. As subgenus of Planorbis 1884. Segmentina Tryon, S. and S. Conch., Ill, p. 107. Type Segmentina lacustris Lightfoot. As genus 1885. Segmentina We.steklund, Fauna Pal. Reg., V, p. 85. Xo type cited. As sub- genus of Planorbis 1886. Segmentina Glessin, Syst. Conch. Cab., ed. 2, XVII, p. 34. Tj'pe Planorbis nitidus Miiller. As genus 1902. Segmentina Westerlund, Rad. Jugoslav. Akad., 151, p. 121. Type Planorbis nitidus Miiller. As subgenus of Planorbis 1905. Segmentina Dall, Alaska Moll., p. 97. Type Planorbis nitidus Miiller. As genus 1912. Segmentina Hannibal, Proc. Mai. Soc. Lond., X, p. 154. Type Planorbis nitidus Miilleir. As subgenus of Planorbis 1915. Segmentina Preston, Fauna Brit. India, Moll. FW. Cast, and Pelec, p. 124. Type Phnwrbis nitidus Miiller. Includes species now referred to Helicorbis, Trochorbis, and Polypylis 1917. Segmentina L. Soos, Ann. Hist. Nat. Musei Hungarici, XV, pp. 140, 142. Type Planorbis nitida Miiller. As genus 1918. Segmentina Walker, Miscel. Pub., Mus. Zool., Univ. Mich., Xo. 6, p. 13. Type Nautilus lacustris Lightfoot. As genus 1919. Segmentina Annand.ale and Prash.\d, Rec. Ind. Mus., XVIII, p. 56. Type Planorbis nitidus Miiller. As genus 1921. Segmentina Germain, Rec. Ind. Mus., XXI, p. 163. T.ype Planorbis nitidus Miiller. As genus 1923. Segmentina Wenz, Fossil. Cat., pars 22, p. 1661. Genotype Segmentina lacustris (Mantagu). As genus 1926. Segmentina Lindholm, Archiv. fiir Mollusk., 58 year. Heft 6, p. 252. Monogeno- type Nautilus lacustris Lightfoot {^Planorbis iiitidus Miiller). As genus 1926. Segmentina Kennard and Woodward, Syst. Brit. Non-Marine Moll., p. 89. Tj^pe Planorbis nitidus Miiller. As genus 1927. Segmentina Pilsbry and Beqluert, Bull. Amer. Mus. N. H., LIII, p. 128. Type Planorbis nitidus Miiller. As genus 1929. Segmentina H.aas, Trab. Museo Cien. Nat. Barcelona, XIII, p. 388. Type evi- dently Planorbis nitidus Miiller. As genus 1931. Segmentir^a Germain, Moll. Terr. Fluv. France, II, p. 542. Type Segmentina nitida (Miiller). As genus 1931. Segmentina Thiele, Handbuch, Teil 2, \). 481. Type Anisus (S.) nitidus (Miiller). As subgenus of Ajiisus 1935. Segmentina A. Soos, Allat. Kozlem., XXXII, p. 29. As genus Shell (plate 79, figs. 1-3). Small, ultradextral, smooth, and glossy; whorls few, notably overlapping the body whorl embracing most of the preceding whorls, causing the preceding whorl to project far within the width of the aperture; periphery rounded or carinated. Cavity of the last whorl restricted by several barriers, each set usually composed of three large transverse lamellae, parietal, basal, and palatal. There may be other smaller lamellae (plate 76, fig. 4). The internal lamellae are composed of enamel-like substance. The embryonic whorls have spiral rows of small pits. 98 The MoUuscan Family Planorbidae Animal. With a short foot, rounded in front, jiointed behind; tentacles fihform, enlarged at the base, the eyes sessile at their inner bases. Edge of mantle thickened. The color of the animal is brownish black much paler when immature. ANATOMICAL CHARACTERISTICS PLATES 2 and 3 GENITALIA. Male Organs (plate 3, fig. 2) . Seminal vesicle sac-like, about three times the diameter of the ovisperm duct with several pro- tuberances near the posterior end. It is about 2 mm. long. Sperm duct long (4.5 mm.) and of small diameter. Prostate moderately long (1.7 mm.) with twenty -two to twenty-five club-shaped diverticula of varying lengths, placed on a separate prostate duct, which joins the sperm duct to form the vas deferens. The free portion of the prostate duct is about 0.7 mm. long and of larger diameter than the sperm duct. In the specimens examined the posterior end of the prostate duct is free of diverticula for about 0.3 nnn. The vas deferens is of medium length (about 3 mm.) and of small diameter. A cross section through the prostate and sperm duct shows the relative position of these parts of the animal (plate 3, fig. 3). The penial complex (plate 3, fig. 1) is very long (about 3 mm.). The preputium (PR) occupies half of the length of the complex and is elongate- pyriform in shape, the upper part swollen. The vergic sac (VS) is very long and narrow, almost tube-like, and is as long as the preputium. There are two short, narrow flagella (FL) at the end of the vergic sac at the point of insertion of the vas deferens. There is a single, rather wide retractor muscle, but no supporting muscles. Internally (plate 2, fig. 2) the preputium presents some striking fea- tures. There is a single heavy ridge on one side (plate 2, fig. 1) which extends vertically up a large portion of the preputium and is in the nature of a pilaster (PL). This ridge merges into a long, sac-like glandular organ which is reflected toward the base or opening of the preputium (SB). This penial gland has a shallow cup, the bottom of which is paved with small protuberances resembling pavement (plate 2, fig. 3), the fleshy sides rolled upward. In cross section this gland presents the appearance shown in fig. 4 of plate 2. On the right side of the preputium there is a long, very narrow pilaster which extends the whole length of the preputium from the external opening upward to the muscular ring (D) separating the preputium from the vergic sac. The large gland is free from attachment to the wall of the preputium and is connected only with the large left pilaster. The verge (V) is long and very narrow. At its distal end it bears a fleshy papilla (plate 2, figs. 5, 6, PA) which is also long and narrow. This papilla is an extension of the verge only from one side, the sperm canal (SC) being in the center of the verge at the end, as shown in the figures. Female Organs. The spermatheca (plate 3, fig. 2) is long and sac-like and is attached to the vagina by a long narrow duct which is somewhat longer than the spermatheca. The spermatheca is constricted about midway of its length. The vagina is narrow and about 0.5 mm. in length. The uterus is about twice the diameter of the vagina and is a trifle over 1 mm. in length. The nidamental gland is very long (about 3 mm.), sac-like, and envelops the uterus. The oviduct is about half the diameter of the SubjaniiUes, Genera, and Subgenera — Recent and Fossil 99 nidamcntal gland and about 1.5 mm. long. The albumen gland is rather small and oval in shape. Hermaphrodite Organs. The ovotestis (plate 3, fig. 2) consists of rela- tively few (less than twenty) large club-shaped diverticula. They are placed in a double row on the ovisperm duct. The ovisperm duct between seminal vesicle and ovotestis is very short, but anteriorly, betw^een the seminal vesicle and the oviduct, it is a long (2 mm.), narrow tube. The figures on plates 2 and 3 agree in the main with those already published by European malacologists. L. Soos's figure (1917, p. 44, fig. 17) is the same, showing the few large ovotestis diverticula, the elongated spermatheca and duct, and the few diverticula on the prostate. The flagella are shown somewhat longer than those in the figure on plate 3. Germain's figure (1931, p. 543, fig. 56) is practically the same, the flagella being more like the figure on plate 3. Respiratory and Renal Systems, The pseudobranch (plate 3, fig. 4) is rather small, smooth, elongate-ovate, and folded. The pneumostome is very large (fig. 4, PS). The kidney (plate 47, fig. 22) is very long (8 mm.) and narrow, ribbon- like, the short ureter reflected at right angles to the kidney. In cross sec- tion (fig. 23, below the middle) it is seen to be rounded, a trifle wider than high, with the veins placed at the upper corners of the lumen, which is oval in sha]K'. There is no superposed ridge. Digestive System. The stomach region (plate 48, fig. 16) is very nar- row, divided into crop, gizzard, and pyloris. There is a short blind sac. The intestine makes a sharp turn about the stomach and another around the liver, then runs forward to the rectum. The buccal sac is much elongated, the salivary glands short, wide, and looped behind. There is a conspicuous radula sac which projects notably from the rear end of the buccal sac. The jaw (plate 50, fig. 24) is horseshoe-shaped, and composed of many small plates (about sixtv). It is similar in form to that of Planorbis. Radula (plate 69, fig. 7). The formula is 23-1-23 with 164 rows of teeth. The central tooth is wdder at the lower edge of the base of attach- ment than at the upper margin of the tooth. The two short cusps do not reach the lower margin of the base of attachment. Lateral teeth (1-7) long and narrow, the reflection low and wide and placed high up on the tooth. There are seven cusps, dagger-like and subecjual in size, the ecto- conic cusps a trifle smaller. There are six teeth which may be called inter- mediate (8-13), since the cusps are a trifle smaller than those of the lateral teeth. ^larginal teeth (14-21) with the reflection very low and wide, 7- cuspid, the mesocone a trifle larger than the three cusps on each side. The outer marginals (22, 23) are vestigial. The teeth are all crow^led on the membrane, some of them even overlapping. The teeth are very uniform in size and shape. Twelve specimens of Segmentina nitida were dissected, collected from marshes in a meadow in Czerniakow, a suburb of Warsaw, Poland, by A. Jankowski. Geographical Distribution. Typical Segmentina is distributed through- out Europe and northern Asia. A single species, 5. nitida (Miiller), is recog- nized, with several races, by Westerlund and others. Some small species, as 100 The Molluscan Family Planorhidae kempi Preston and angusta Jickeli, may be true Segmentina. Species quoted from northern Africa probably belong to other genera, as Ajropla- norbis. South African species may belong to an undescribed group. The Indian and Chinese species included by authors in Segmentina probably all belong to Poli/pylis, Pingiella, or Helicorbis. Only an anatomical ex- amination can correctly place the many species referred to segmentina. Geological Distribution. Oligocene period to Recent fauna. Species Considered as Valid. Since the genus Segmentina is not found in America, it is extralimital to the scope of the present work. Segmentina 7}iti(Ja (Miillerl, the genotype, is the only species definitely considered. Remarks, The genus Segmentina is distinguished not only by its glossy shell with the embracing body whorl and internal barriers, but also by its genitalia with the two short flagella on the verge, the few large ovotestis diverticula, the ductless penial gland in the preputium, and the papilla at the end of the verge. No mention is made of this peculiar gland in any w^ork consulted. The prostate is on a separate duct as in the Planorbinae. These special features of the anatomy distinguish Segmentina from all other genera of Planorbidae. The generic name has been used in a rather wide sense and has included one group which belongs in another subfamily {Planorbula) and several other related groups which are separated generically from Segmentina {Popypylis, Pingiella, Helicorbis) . As typified by Planorbis nitidus Miiller it is a well characterized genus. Segmentina nitida appears to be a favorite host for parasitic worms, all of the twelve specimens examined being more or less heavily infested. The ovotestis appeared to be most affected and in several specimens this organ was almost obliterated. The liver was also affected. Genus HIPPEUTIS (Agassiz AISl Charpentier, 1837 Type designated by Clessin in 1886, Pknwrbis complanatus Drap. {= Helix jontana Lightfoot), one of the two species originally included 1837. Hippeutis 'Aga.ssiz' in J. de Ch.^rpentier. Neue Denksch. Allg. Schweiz. Naturw., I, No. 2, p. 22. As subgenus of Planorbis 1837. Hippeutis Gr.\y, in Turton, Man. Land FW. Shells Brit. IsL, Ed. 2, p. 243. As subgenus of Planorbis 1844. Hippeutis Hartm.\nn, Erd-und Siisswussser-Gast. der Schweiz., V, pp. 51, 87. As subgenus of Planorbis 1850. Hippcutes M. E. Gr.\y, Fig. Moll. Anim., IV, S^vst. Arrang., p. 119. Typographi- cal error for Hippeutis 1850. Segmentina (part) Stein, Leben. Schneck. Muschl. Berlins, p. 78. Xon Seg- mentina Fleming, 1817. (Segmentina plus Hippeutis) 1855. Hippeutis Moquin-T.4Ndon, Hist. Moll., Terr. Fluv. France, II, pp. 423, 426. Type Planorbis jontanus (Lightfoot). As genus 1885. Hippeutis Westerlund, Fauna Palearc. Reg. Binnen. Conch., V, pp. 65, 84. No type cited. As subgenus of Planorbis 1886. Hippeutis Clessin, Syst. Conch. Cab., Ed. 2, XVII, p. 34. Type Planorbis com- planatus Drap. As subgenus of Planorbis 1902. Hippeutis Westerlund, Rad. Jugoslav. Akad., 151, p. 121. Type Planorbis jontanus (Lightfoot). As subgenus of Planorbis 1905. Hippeutis D.\ll, Alaska Moll., pp. 82, 86. Type Planorbis fontanus (Lightfoot). As subgenus of Pla^wrbis 1912. Hippeutis H.-vnnib.al, Proc. Mai. Soc. London, X, p. 154. Type Planorbis com- planatus Drap. (= Helix jontana Lightfoot). As subgenus of Planorbis I Subfamilies, Genera, and Subgenera — Recent and Fossil 101 1915. Hippcutiii Prestox, Fauna Brit. India, Moll., FW. Gast and Pelec, p. 124. Type Planorbis jontanus (Lightfoot). As section of Phuiorbia 1918. Hippeutis Walker, Mis. Pub. Zool. Mus., Univ. Mich., No. 6, p. 94. Type Pla- norbis jontanus (Lightfoot). As subgenus of Planorbis 1923. Hippeutis Wexz, Fossil. Cat., Pars 22, p. 1633. Genotype Hippeutis compla- natus (Drap.) = Helix jontana Lightfoot. As genus 1923. Hippeutis Germ.ain, Rec. Ind. Mus., XXI, pp. 8, 159. Type Planorbis jontanus (Lightfoot). As subgenus of Planorbis 1926. Hippeutis Lixdholm, Archiv. fiir Mollusk., 58 year, Heft 6, p. 253. Ideogeno- type Planorbis complanatus Drap. As genus 1926. Hippeutis Kenxard and Woodward, Syn. Brit. Non-Marine Moll., p. 69. Type Helix complanatus Linn. As subgenus of Planorbis 1927. Hippeutis Pilsbry and Bequaert, Bull. Amer. Mus. N. H., LIII, p. 128. Type Planorbis complanatus Drap. = P/«nor6zs jontanus (Lightfoot). As subgenus of Planorbis 1929. Hippeutis ^as, Trab. Museo Cien. Nat. Barcelona, XIII, p. 387. Type evidently Helix jontana Lightfoot. As genus 1931. Hippeutis Germaix, Moll. Terr. Fluv. France, II, p. 541. Type not cited but Planorbis complanatus (Linn.) described. As subgenus of Planorbis 1931. Hippeutis Thiele, Handbuch, Teil 2, p. 481. Type Anisus (H.) complanatus (Linn.). As subgenus under genus Anisus 1935. Hippeutis A. Soos, Allat. Kozlem., XXXII, p. 29. As subgenus of Segmentina. No tj-pe cited Shell (plate 79, figs. 4-6). Small, ultradextral, lens-shaped, shining, the body whorl very wide and overlapping most of the inner whorls and form- ing a sharp keel at the periphery, the preceding whorl forming a sharp extended ridge on the parietal side of the aperture. Aperture triangular, outer lip thin. There are no barriers or lamellae within the aperture. The embryonic whorls have spiral punctures as in Segmentina. Animal. Not differing from that of Segmentina in general form. The body of the animal is clear and translucent. ANATOMICAL CHARACTERISTICS PLATE 2 {Hippeutis complanatus (Linn.) ) GENITALIA. Male Organs (fig. 15) . Seminal vesicle rather short (about 0.7 nun.), placed midway between ovotestis and oviduct, the di- ameter of the organ about the same as the ovosperm duct, with many pustule-like vesicles. Prostate short (about 0.6 mm.) with ten long and narrow diverticula. Free portion of prostate duct short (fig. 8). Sperm duct iSPD) long (over 1 mm.) and of large diameter. Vas deferens (VD) about as long as sperm duct, but of smaller diameter. Penial complex (plate 2, fig. 14) less than 1 mm. long. Preputium (PR) strikingly pyriform, tapering to a narrow neck near the outlet. Vergic sac (VS) shorter than the preputium, sac-like, of much smaller diameter than the preputium. There are two short flagella (FL). There is a single wide retractor muscle (RM) attached to the preputium at the lower part of the bulbous swelling. Internally (fig. 12), the preputium has two large fleshy pilasters (PL), to the left one of which is attached a large, sac-like penial gland, which extends crosswise of the preputial cavity (SB). There is a depression at the end of the gland but apparently no cavity or cup. The square end of the gland is folded backward upon itself. It is shown folded in fig. 12 (SB) and with the end stretched out in fig. 9, where the small depression may be 102 The Molluscau Family Planorhidae plainly seen. The retractor muscle (RM) is attached to the preputium at the point where the gland joins the pilaster (fig. 12, SB). The verge is swollen above and tapers to a narrow diameter for about half its length (V). The sperm canal has a central outlet but there is no papilla. There is a narrow muscular ring or diaphragm (D) between vergic sac and preputium. The two short flagella (FL) are hollow and under high power show a minutely punctate surface at the upper rounded end (fig. 11). Female Organs (fig. 15) . The spermatheca (S) is long, ovate, sac-like and is joined to the short, wide vagina (V) by a long, tube-like duct, which is twice the length of the spermatheca. The uterus (U) is twice as wide as the vagina, and shorter than the spermatheca and its duct. The nidamen- tal gland (NG) is longer than the uterus, much swollen and about half as wide as long. The oviduct (OD) is short (about 0.5 mm.) and about the same diameter as the uterus. There is a large, bulbous carrefour (CF) which receives the duct from the long and narrow albumen gland (AL; also fig. 10). Hermaphrodite Organs. The ovotestis (OT) has about thirty club- shaped diverticula jilaced for the most part in a double row (fig. 7). The ovisperm duct (SO) is very long (about 2 mm.) and of small diameter. Odhner (1929, p. 32, fig. 13) figures the genitalia of this species agree- ing in most resi)ects with the material personally examined. A few points, however, are figured differently from the position observed in the speci- mens studied. The prostate is shown as having thirteen diverticula rather widely spaced on the sperm duct, cjuite different from the long, crowded diverticula personally observed (see plate 2, fig. 15, PES). The ovotestis diverticula are shown extending in pairs from a short duct which enters the ovisperm duct. In this species, as well as others of this subfamily and of Planorbinae, the ovotestis diverticula arise in pairs directly from the ovisperm duct, each diverticulum entering the duct separately (see plate 2, fig. 7). No mention is made of a separate prostate duct or of a gland in the preputium. An elongated object in the upper part of the prej^utium is shown in Odhner 's figure which might represent this organ. Odhner's figure of the radula of Hippeutis complanatus differs some- what from the radula as personally examined, there being no interstitial cusps between the larger cusps. The formulas of Odhner's specimens agree exactly with ours. Respiratory and Renal Systems. The pseudobranch (plate 2, fig. 13) is small, rather narrow, and })ierced above by the rectum (P). The pneu- mostome is very large. The kidney (plate 46, fig. 17) is rather short (1.5 mm.) and wide, the greatest width being almost one third of the length. The ureter is not sharply reflexed as in Segmentina, but extends horizontally into the mantle cavity. A cross section below the middle (fig. 18) shows the kidney to be flattened, the lumen rounded with the veins placed at the upper corners of the lumen. There is no superposed ridge. The kidney of Hippeutis is quite different from that of Segmentina (compare fig. 17, plate 46, with fig. 22, plate 47). Digestive System. The stomach (plate 48, fig. 12) is elongated, as in Segmentina. The intestine loops around the stomach and liver, and there Subfmnilies, Genera, and Subgenera — Recent and Fossil 103 is a larj^e blind sac. The buccal sac is elongated, narrowed in front with a large radiila sac behind. The salivary glands are short and do not extend far beyond the posterior end of the buccal sac. They are joined behind as in Scgmcntina. The jaw is fragmented as in Segmentina and is made up of many small plates. The radula formula is 16-1-16, with 150 rows of teeth. The center tooth is higher than wide with two wide cusjis which do not reach the lower margin of the base of attachment. The laterals (1-9) are squarish and tricuspid, the mesocone large and almost reaching the lower margin of the base of attachment. The entocone is shorter than the mesocone. The cctocone is shorter than the entocone and is placed high on the margin of the tooth. In the marginal teeth the reflection is wide and low and is placed high u\) on the tooth. The entocone and mesocone are of equal length and the ectocone is shorter with two small cusps above on "the outer margin of the tooth. The radula teeth of Hippeutis resemble those of Bathyomphahis contortus shown on plate 68, fig. 1. They are not like those of Scgmcntina nitida figured on plate 69, fig. 7. The above anatomical information was obtained from specimens col- lected in a pool on a meadow in Jabtonna, 16 km. north of Warsaw, Poland. The specimens were obtained by Mr. A. Jankowski. Geographical Distribution. Europe from Great Britain, Norway, and Sweden south to Portugal. Italy, and Albania. Eastward to northern Siberia. A palearctic group. It has been recorded from northern Africa and the group may be circum-]\Iediterranean in distribution. As in Segmentina a number of species have been described with many varieties. The species cited from South x\frica, India, and China probably belong in other genera. Species Considered as Valid. The following species are apparently referable to Hippeutis: Hippeutis complanatus (Linn.) Hippeutis raymondi (Bgt.) Hippeutis riparius (Westerlund) Hippeutis junodi (Connolly) Hippeutis syraciisanus (Cafici) Hippeutis benguelensis (Dunker) Hippeutis diaphaneUus (Bgt.) Geological Distribution. From the Lower Eocene period (Wenz). Eighteen species and races of fossil Planorbis are referred to this genus by Wenz. Remarks. Hippeutis complanatus resembles Segmentina nitida in its anatomy. The prostate, however, has fewer diverticula. The penial gland differs in shape but both are attached to the right pilaster. The whole genitalia of Segmentina are much elongated while these organs in Hippeutis are short and heavy. Internally the penial complex of the two groups differs in details. The kidneys of the two genera are quite unlike. The radula resembles Bathyomphahis rather than Segmentina. The shell is wholly without barriers or lamellae of any kind within the aperture and this characteristic at once marks Hippeutis as a separate genus. Species from northern Africa and eastern Asia have been assigned to Hippeutis but until these species have been examined anatomically this reference remains open to doubt. The Asiatic forms probably belong to Benson's genus Helicorbis. Parasites were not observed in any of the material examined. 104 The Molluscan Family Planorhidae Genus POLYPYLIS Pilsbry, 1906 Type by original designation Segmentina largillierii (Dunker)(= S. hemisphaerula (Benson) ) 1906. Polijpylis Pilsbry, Proc. Acad. Nat. Sci. Phil., LVIII, p. 166. Type Segmentina largillierti (Dunker). As subgenus of Segmentina 1921. Segmentina (part) Prashad (non Fleming), Rec. Ind. Mus., XXII, p. 585. Mentions Segmentina calathus (Benson), included in Polypylis 1922. Segmentina Annandale (non Fleming), Rec. Ind. Mus., XXIV, p. 362. Mentions Planorbis calathus Benson and Planorhis caenosus Benson, both included in Polypylis 1923. Polypylis Germain, Rec. Ind. Mus. XXI, p. 164. As synonym of Segmentina 1939. Polypylis Haas, Field Mus. N. H., Zool., Miscel. Notes, XXIV, p. 96, fig. 8a. Type Segmentina largillierti (Dunker) (= , penultimo valde convexo, ultimo majori, versus suturam obtuse angulato, extus depresso, interne acute carinato, intus laminis rarissimis jileurumque minuto, subtus piano, medio, versus umbilicum inconspicuum, leviter excavato, versus periphaeriam vix declivi; apertura oblic|ua subsagittata, marginc suj^criori arcuato, jn'ominente, inferiori recidente. Diam. 3 mm., axis vel 2' (Benson, 1850, p. 352). 'The infrequency and irregularity of the internal laminae in this species, causing them to look more like accidental thickenings of the shell, made Subfamilies, Genera, and Subgenera — Recent and Fossil 109 me overlook this structure in my original description. The species is singu- lar from the nearly total absence of umbilicus' (Benson, 1850, p. 352). The shell is treated as dextral (ultradextral). Animal. The anatomy of this species is at present unknown. Geographical Distribution. Barrackpore, Bengal, India. Species Considered as Valid. Trochorbis trochoidcus Benson, the genotype, is the only species assigned to this genus. Remarks. In 1850 (p. 352) Benson noted the trochoid form and small umbilicus of Pkuwrbis trochoidcus and in 1855 (p. 126) erected the group Trochorbis for it. This name has l)een overlooked by most writers on Asiatic mollusks. Dall (1906, p. 105) considered Trochorbis a synonym of Secjmentina. In Preston's Fauna of British India (1915, p. 125) the species appears as Planorbis iSegmentina) trochoideus without reference to its use as type of Trochorbis. Germain (1921, p. 175) does not mention the group name proposed by Benson and places the species trochoidcus in the genus Segmentina. Kennard and Woodward (1926, p. 90) consider it an absolute synonym of Segmentina. Trochorbis is not recognized by Annandale and his co-workers in the studies of the mollusk fauna of the Indian Empire. Typical Segmentina is not found in eastern Asia, the species previously referred to that genus now being placed in the genus Polypylis of Pilsbry. Trochorbis trochoideus greatly resembles Plartorbis calathus Benson which belongs to the genus Polypylis and from the shell characters appears to be only specifically distinct from calathus, U one can judge from the very excellent figures of both species in Hanley and Theobald, Conchologia Indica, plate 39, figs. 1-3 (calathus) and 4-6 (trochoideus) . The species trochoideus has a much smaller shell than calathus and the periphery is more acute. According to Benson, the apertural lamellae are so weak that he overlooked them in his first description of the species. The Asiatic mollusks allied to Segmentina have shown such diversity in anatomical characteristics that until the animal of trochoideus is examined it seems best to treat Trochorbis as a separate genus. Its place, as far as can be judged at present, is near the group of shells called Polypylis, with the internal lamellae far within the aperture. Genus PINGIELLA F. C. Baker, New Genus Type Pyramidula (P alula) peipinensi.^ Ping and Yen 1932. Pyramidula (Patula) peipineiisis Ping and Yen, Bull. Fan Memorial In.st. Biol., Ill, p. 25, figs. 1-3. Wrongly interpreted as a land shell. 1938. Ani-fu.^ (Hippeutis) peipinenf^is Mori, Mem. Col. Sci., Kvoto Imp. Univ., Ser. B, XIV. Xo. 2, p. 288, plate 14, fig. 6. Shell (plate 78, figs. 8-10). Ultradextral, lenticular, flattened, with sharp i^eripheral carina, the last whorl very large and strongly overlapping or clasping the preceding whorls, the base flattened, with a narrow spire dejiression exhibiting all of the whorls, the depression about one third of the diameter of the shell. Aperture without internal lamellae. Major diameter of shell 7.8 mm. to 8.6 mm. The embryonic whorls are pitted. Animal. Foot and pneumostome lead color, body yellowish finely mottled with black. Kidney pigmented (from alcoholic specimens). 110 The Molluscau Family Planorhidae ANATOMICAL CHARACTERISTICS PLATE 4 GENITALIA. Male Organs (plate 4, fig. 9) . Seminal vesicle (SV) large, tortuous, more than double the diameter of the ovisperm duct, with several vesicles, but mostly tubular. Sperm duct, long (3.5 mm.), narrow. Prostate (PRS) about 2 mm. long with twenty to twenty-two long diverticula. Free portion of prostate duct very short. Vas deferens long (4 mm.) and tubular. Penial complex (fig. 5) with a large, sac-like preputium (PR) and small, narrow, short (little more than 0.5 mm.) vergic sac (VS). The vergic sac is placed on the side of the upper part of the preputium. There are two flagella, short and wide, placed on tube-like ducts longer than the whole penial complex. The sac-like flagella (FL) are turned hori- zontally to the tube-like duct. There is a very long and very fine, tube-like external penial duct ( DC ) , about three times as long as the penial complex when stretched to its fullest extent. There is a single, wide retractor muscle (R]\I) attached about midway of the i:)reputium at the point where the penial duct has its exit. Internally (plate 4, fig. 6) ,. there is a short, wide pilaster which bi- furcates about midway of the preputial cavity, one branch forming a wide, flat gland (GL) which is doubled backward at the end (fig. 6). The other branch is short and narrow and ends above in a rounded, disc-like organ (G). The very long duct (DC) which appears on the outside of the preputium, enters a canal in this small branch (fig. 2, C, fig. 7, C) which terminates on the underside of the reflexed end of the gland (fig. 7, GL). Tlie other end of the penial duct passes on the outside of the small pilaster and enters the round, turban-like termination of the small pilaster (figs. 2, 6, G and DC). There is a thickened muscular ring or diaphragm be- tween the vergic space and the preputial space (figs. 6, 8, D). The retractor muscle is attached to the preputium near the small liranch of the pilaster (fig. 6, RM). The verge (fig. 8, V) is long and narrow, swollen or pear-shaped at the upper part but narrowed and tubular below. The lower end of the verge is notably flattened and broad, with a small penial papilla at the end, just beside the sperm canal exit, which is in the center of the verge (figs. 3, 4). The sac-like portion of the flagella is large and the cavity is lined with elliptical cells which show on the exterior surface as small, rounded pro- jections (fig. 5, PL). The duct of the flagellum is narrow but is of greater diameter than the vas deferens. Female Organs, The spermatheca is globe-shaped (S) with a short, narrow duct about as long as the greater diameter of the spermatheca (SD). Another specimen had a spermatheca long and sac-like (fig. 5, plate 5) attached to the vagina by a very short wide duct. This spermatheca contained a spermatophore and the specimen was evidently in gravid con- dition. The form of the spermatheca evidently varies with the breeding condition of the animal. Vagina rather short but longer than wide (VG). Uterus (U) short and as narrow as the vagina. Nidamental gland (NG) veiy long (3 mm.) and much swollen. Oviduct (OD) short and narrow. Albumen gland ( fig. 1 ) elongated, about twice as wide as long, placed over the stomach, the intestine looped beneath it. Subfatnilies, Genera, and Subgenera — Recent and Fossil 111 Hermaphrodite Organs. The ovotestis (OT) consists of many long and narrow diverticula placetl in a double series. The ovisperni duct (SO) is of small diameter. The portion between the seminal vesicle and the ovo- testis is very short (less than 1 mm.) but the portion between the seminal vesicle and the oviduct is very long (about 3 mm.). An egg capsule on one of the shells, presumably of this species, con- tained eight eggs. Respiratory and Renal Systems. The pseudobranch (plate 5, fig. 1, P) is small and inconsjncuous, resembling that of Hippenfis. Tiie kidney is long and narrow, resembling that of Segmentina, but not as long. The ureter is directed horizontally into the mantle cavity, not reflected. There is no superposed ridge. A section of the kidney near the middle shows a wide and low lumen about three times as wide as high with the veins at the upper corners. A section below the middle shows a flatter form with the lumen almost as high as wide and somewhat tri- angular, the veins at the upper part of the triangle. This triangular form is caused by the acute angle of the shell on the periphery. Digestive System. The stomach is long and narrow as in Segmentina, the intestine making a loop around the stomach and another around the liver and then passing forward to the rectum and pseudobranch. The blind sac is very short and pointed below. The buccal sac is elongated, pear-shaped, the radula sac large and near the middle of the posterior end. The salivary glands extend considerably beyond the rear end of the buccal sac and are united behind; the ducts are small and tube-like. The jaw is fragmented with about eighty plates. It is horseshoe-shaped as in the other groups of this subfamilv. Radula formula 26-1-26 with 160-170 rows of teeth. The teeth resemble those of Segmentina and Polypijlis (see j^late 69, figs. 7, 8). The laterals have six short, spade-shaped cusps and the marginals have seven short cusps. The anatomical details have been obtained from three specimens from Peiping, China, received from the Fan Memorial Institute of Peiping, through the courtesy of Dr. Chi Ping. Geographical Distribution. Northern and eastern China and Japan. It is probable that this distribution will be extended when more material has been examined from China and India. Geological Distribution. Unknown. Species Considered as Valid. Pingiella peipinensis (Ping and Yen), the genotype, is the only representative of this monotypic genus. Remarks. This genus is remarkable for the peculiar characteristics of the penial comj^lex, the penial gland, bifurcated into a large and a small branch, the latter with a turban-shaped termination, and the very long, tube-like external duct with its peculiar gland terminations. The terminal end of the verge is also peculiar. The flagella are notable in having the long ducts and the small, sac-like glands. These differences are sufficient to stamp the species as belonging to a new and hitherto unknown generic group. It differs from Segmentina in the possession of an external duct and from Polypylis by having a penial gland which is absent in that genus. 112 The Molluscan Family Planorhidae It is quite probable that other species belong in this genus and will be discovered when examined anatomically. Mori ( 1938, p. 288) has called attention to the fact that this species is a planorbid and not a land shell. He, however, places the species in the genus Anisus, subgenus Hippeiitis, following the classification of Thiele. The anatomy, especially the genitalia, indicates that this species can not correctly be referred to either Anisus or Hippeutis, differing widely in its internal organization. The genus is dedicated to Dr. Chi Ping, research professor in the Fan Memorial Institute of Biology, Peiping, China, an accomplished student of the Asiatic molluscan fauna. Dr. Ping has supplied the author with a num- ber of mollusks for anatomical study from near Peiping. Genus IXTHA Annandale, 1922 Type b}^ original designation Intha capitis Annandale 1922. Intha Ann.^nd.^le, Rec. Ind. Mus., XXIV, p. 361. Type hitha capitis Annandale. As genus. 1931. Intha Thiele, Handbuch. Teil 2. p. 482. Anisus (I.) capitis (Annandale). As sub- genus under genus Anisus. Shell. Tn this genus the body-whorl, though relatively smaller than it is in Hippeutis, completely embraces- and occludes the rest of the shell in such a way that the spire is entirely concealed, except in so far as it can be detected by transparency. The shell is very minute and has few whorls, which increase in size rapidly. Those of the spire are cylindrical, but the body whorl is flattened below and has the form of a flattened conoid slightly truncate above. The outer lip arises in the middle of the upper surface and forms a small lobe at its point of origin. The aperture is large and very oblique but with a cordate outline. There is a well-developed simple callus on the inner lip, but internal ridges are completely absent. The lower surface is narrowly umbilicate. The external surface is prac- tically smooth' (Annandale, p. 361). The shell is ultradextral. No figure of the shell is available and the single specimen used for dissection had the shell badly broken which made it unfit for illustration. Animal. 'The animal is remarkable externally for the large upper and lower lobes into which the mantle is divided. The pseudobranch is poorly developed' (Annandale, p. 362). The head of the animal bears short, blunt tentacles (plate 8, fig. 3). AXATOMICAL CHARACTERISTICS PLATE 8 GENITALIA. Male Organs (fig. 11). Seminal vesicle (SV) very large, about three times the diameter of the ovisperm duct, with a few irregular, pointed, glandular projections. It is less than 1 mm. long. Sperm duct (SPD) long (slightly more than 1 mm.) and of large diameter. Prostate short, with six large, club-shaped diverticula. Prostate duct (free portion) about as long as the prostate. Vas deferens (VD) of small diameter and very long (about 5 mm. when stretched out). The penial complex has a large, bulbous preputium (PR) and a small, slender vergic sac (VS), somewhat shorter than the preputium (fig. 6). Together both organs measure 1 mm. in length. There is a short, narrow Subfamilies, Genera, and Subgenera — Recent and Fossil 113 penial gland duct on the outside of the i)reputiuni, emerging from the latter about midway between the outlet and the summit of the preputium. At the upper end of the vergic sac there are two very large fiagella (about 1 mm. long) which are sausage-shaped and are attached to the vergic sac by a very short duct, in fact they are almost sessile. Small glands on the interior of the fiagella show through as white circles, as shown in the figure (fig. 11, FL). There is a wide retractor muscle which is attached to the upper part of the preputium. Internally (fig. 8), the preputium has a large penial gland (GL) which is attached to the preputium only at its base, the cup being free. It is more or less circular in shape, depressed, with a wide cup-shaped depression in which the walls are ridged (probably glandular). There is a short duct, external to the 'preputial cavity, which enters a round, fleshy ring or diajihragm between the vergic and jn-eputial cavities (fig. 8, D). The rela- tionship of the gland and duct to the preputial sac is well shown in fig. 7. The verge (V) is narrow, tapering, with the exit at the end in the center. There is a very small papilla at one side of the opening (fig. 4). The two fiagella are joined in one tube before thev enter the vergic sac (fig. 11, VS; fig. 8. FL). Female Organs (fig. 11). The spermatheca (S) is large and almost circular, and is joined to the short, wide vagina (V) by a duct which is shorter than the diameter of the spermatheca. The uterus (U) is wide and shorter than the spermatheca and its duct. The nidamental gland (NG) is very wide, sac-like, and about twice as long as the uterus. The oviduct (OD) is short and wide, about as long as the preputium. There is a large carrefour (CF). The albumen gland (AL) is large, about 1 mm. long, and has a space for the passage of the intestine (fig. 1) . Hermaphrodite Organs. The ovotestis (OT) is large with the diver- ticula long and clul)-shaped. They are placed in a double series. The ovi- sperm duct (OS) is very short between the seminal vesicle and the ovotestis and about 1 mm. long between the seminal vesicle and the ovi- duct. A spermatophore of peculiar form was found in the spermatheca No figure or descri]ition has been published of the genitalia of this genus. Annandale says of the genitalia: 'The male organ resembles that of Planorbis, except that the penial bulb is relativelv verv large' (op. cit., p. 362). Respiratory and Renal Systems. The pseudobianch (fig. 2, P) is a flatly rounded, simple lobe, pierced above by the rectum. The kidney (plate 47, fig. 26) is wide and fiattened and not as long as in Segmentinn or Poh/pi/Us. There is no superposed ridge. In section (fig. 27) the lumen is long, oval in outline with the veins about in the center on each side. Digestive System. The stomach is narrow as in Segmentina, the intes- tine making the same loops around the stomach and liver as in the genus Segmentina. The buccal sac resembles that of Segmentina. The jaw (plate 50. fig. 23) is fragmented as in Segmentina. There arc more than sixty plates on the jaw. The radula has the formula 15-1-15 with over 125 rows on a liroken membrane (iilate 69, fig. 9). Center tooth bicuspid, the cusps not reaching the lower margin of the base of attachment. Lateral teeth (1-5) with two 114 The MoUuscan Family Planorhidae entocone cusps, a single raesocone, and three ectocone cusps, the mesocone a trifle larger than the other cusps. Marginal teeth 7-cuspid (6, 8, 11, 12) with three small cusps on each side of a mesocone cusp. There are no intermediate teeth. The teeth are all in a straight row. They are very uniform in size and shape but become narrower toward the outer edge of the membrane. The teeth are essentially like those of Segmentina. For the above anatomical details a single specimen was dissected, received from Dr. H. S. Rao, collected by Dr. N. Annandale in Inle Lake, southern Shan States, Burma. Geographical Distribution. Known at present onlv from the tvpe locality, He-Ho and Inle valleys (3000-3800 ft. alt.) southern Shan States, Burma. Recent and fossil. Species Considered as Valid. Intha capitis Annandale is the only species recognized for this monotypic genus. Remarks. Intha is peculiar in the form of its shell and also in the characteristics of its genitalia, with the few prostate diverticula of large size, the two enormous flagella, and the striking penial complex with a penial gland which has a small, short duct entering the circular ring be- tween the vergic sac and the preputium. In this respect it resembles some of the Helisomatinae (typical Helisoma) but differs in the form of the prostate and ovotestis. It appears to be another peculiar variant of the Segnientina group of Planorbidae. Genus DREPANOTREMA Fischer and Crosse, 1880 Monogenotype Planorbis yzabolensis C. and F. (= Pkinorbis anatinum d'Orbigny) 1880. Drepanotrema Fischer and Crosse, Miss. Scient. Mex., Moll., II, pp. 59, 75. Type Planorbis yzabalensis C. and F. As subgenus. 1883. Drepanotrema Fischer, Man. de Conch., p. 509. Type Planorbis yzabalensis C. and F. As section of Planorbis. 1884. Drepanotrema Tryox, S. and S. Conch., Ill, p. 107. Type Planorbis yzabalensis C. and F. As subgenus of Planorbis. 1884. Bathijomphalus Tryon (non Agassiz, 1837), S. and S. Conch., Ill, p. 106. Pla- norbis anatinus Orb., cited as example. 1884. Ayiisus Tryon (non Studer, 1820), S. and S. Conch., Ill, p. 106. Planorbis kertnatoides Orb., cited as example. 1899. Drepanotrema M.artexs, Biol. Cent. Amer., Moll., p. 397. As synonym of Hippe litis. 1899. Spiralina M.^rtexs, (part) op. cit., p. 395. Includes Drepanotrema cultratum and sumichrasti. 1899. Hippeutis Martens (non Agassiz, 1837), op. cit., p. 397. Cites Plaiiorbis yzabal- ensis, type of Drepanotrema. 1905. Drepanotrema D.\ll, Alaska Moll., p. 82. Type Planorbis yzabalensis C. and F. As section of subgenus Hippeutis. 1921. Drepanotrema Germain, Rec. Ind. Mus., XXI, p. 8. Type Planorbis yzabal- ensis C. and F. As subgenus of Planorbis. 1930. Drepanotrema H. B. Baker, Oc. Papers, Mus. Zool., Univ. Mich., No. 210, pp. 43, 38, 51. Type Planorbis yzabalensis C. and F. As genus. 1931. Drepanotrema Thiele, Handbuch, Teil 2, p. 481. Type Drepanotrema yza- balensis C. and F. Section of Gyraulus, subgenus of Planorbis. 1934. Drepanotrema Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 58. Type Planorbis yzabalensis C. and F. As genus. Figures genitalia of D. lucidum (Pfr.) and D. cultratum (Orb.). Subfa/fnlies, Genera, and Subgenera — Recent and Fossil 115 Shell (plate 79, figt;. 16-18). Small, iiltradextral, of few whorls, the body whorl large and expanded, embracing the previous whorl; whorls rounded or carinated; the right side with whorls sunken below the upper surface or showing a wide, slightly concave depression. There are no barriers or lamellae within the aperture. The embryonic shell is punctate. Animal. The body is long and narrow, rounded before and sharply pointed behind. The tentacles are long and filiform, the eyes large and conspicuous, placed at the inner base of the tentacles. There may be two dark lines of color extending down the neck and top of the head. In some species (as melleus Lutz, plate 78, figs. 1, 2) the body is not much pig- mented, but in some others (as hoffmani F. C. Baker, plate 10, fig. 1) the l)ody is dcei^ly jngmented with black. ANATOMICAL CHARACTERISTICS PLATES 9, 10, 11 GENITALIA. Male Organs (plate 9, fig. 2; plate 10, fig. 2; plate 11, fig. 3, respectively anatinum, hoffmani, and lucidum) . Seminal vesicle (SV) large, much elongated, swollen, two to three times the diameter of the ovisperm duct, varying in length in the three species examined. It is about half the length of the ovisperm duct region in hoffmani but only about a third of this lengi:li in lucidum. Anatinum is much like hoffmani. The prostate (PRS) varies greatly in the three species: in hoffmani it is 3.5 mm. long and is made up of twenty-three short, club-shaped, widely spaced diverticula; in lucidum, there are but eight diverticula on a prostate about 1 nun. long; in anatinum, there are seven diverticula still more widely sjiaced and the prostate is about 1 mm. long. All diverticula arise directly from the sperm duct and are not on a separate duct as in Segmentina and other members of the subfamily. The sperm duct (SPD) also varies in length, being 5 mm. in hoffmani, 2.3 mm. in lucidum and a little over 1 mm. in anatinum. These lengths do not include the sperm duct portion under the prostate diverticula. The vas deferens of the three species is always a long, narrow tube, varying in length in the different species. The penial comi~)lex is much elongated in all species examined. In hoffmani (plate 10, fig. 5) the preputium is elongated, cylindrical, and about twice the diameter of the long and narrow vergic sac, which is nearly twice the length of the preputium. In lucidum, the preputium is about three times the diameter of the vergic sac, which is considerably longer than the preputium (plate 11, fig. 4). In another specimen, the preputium and the vergic sac were about equal in length (plate 11, fig. 51. In anatinum (plate 9, fig. 1), the vergic sac is shorter than the preputium, which forms a reversed cone, becoming smaller in diameter toward the ui^i^er part. The flagella of the three species differ considerably. In hoffmani (plate 10, figs. 6, 7, 8), the flagcllum is very short and is bifid at the end; in lucidum (plate 11, figs. 4, 5), the flagellum is very long (1 mm. or more) and is not bifid at the end; in anatinum (plate 9, fig. 1), the flagellum is as long as the preputium (0.6 mm.) and is bifid at the end. A strong retractor muscle is attached to the end of the vergic sac near the insertion of the flagellum (plate 10, fig. 7). There is also a large nerve at this point (N). 116 The MoUuscan Family Planorhidae Internally, the penial complex is simple in all species studied and re- sembles the condition observed in hoff)nani (plate 10, fig. 6). There are three rather heavy pilasters, a small muscular ring or diaphragm between the preputium and the vergic sac, and a very long verge completely filling the vergic sac (V). The verge is narrow at the end with a central sperm outlet (plate 10, fig. 9). Female Organs. These also differ in the three species. In hofjmani (plate 10, fig. 2 1 the spermatheca is pyriform and is joined to the long and narrow vagina by a duct twice as long as the spermatheca; in lucidum the spermatheca (plate 11, fig. 3) is globular, much wider than in hoffmani, and is connected with the vagina (which is shorter than in hoffmani) by a duct a trifle longer than the spermatheca; in anatinum (plate 9, fig. 2) the spermatheca is wider than in hoffmani but not as globular as in lucidum and is attached to the narrow vagina by a duct almost three times as long as the spermatheca. The uterus (U) is very long and narrow in hoffmani, shorter and wider in lucidimi, and narrow in anatinum. The nidamental gland is long and wider than the uterus in all three species. The oviduct (OD) is very long and narrow in hoffmani (about 5 mm. long), much shorter in lucidum (about 2 mm.) and very short in anatinum (less than 1 mm.). There is a small and inconspicuous carrefour (CF) in all species. The albumen gland is much elongated (plate 10, fig. 4). Hermaphrodite Organs. The ovotestis (OT) consists of a few club- shaped diverticula placed in a double series. The ovisperm duct is much longer in lucidum than in either hoijmani or anatinum (see plate 9, fig. 2; plate 10, fig. 2; plate 11, fig. 3). Several specimens of lucidum had the male genitalia completely everted and lying on the body of the animal (see plate 11). In fig. 1, the preputium is fully everted and the verge is extended to its fullest extent. In fig. 2, only the preputium is everted. In fig. 6, the organs are diagrammatically shown so that the relationship of the different parts may be seen under this condition. The flagellum, vergic sac, vas deferens, and retractor muscle remain in the body of the animal just behind the male ojiening. This is shown to better advantage in fig. 7. Pilsbry (1934, p. 59, fig. 6, F) figured the penial complex of lucidum (from sketches by H. B. Baker). This figure differs from the specimens here examined in having a shorter flagellum and in having the penial re- tractor attached to the preputium instead of to the vergic sac. In all speci- mens of Drepanotrema examined, the retractor muscle was inserted at the end of the vergic sac near the flagellum and not at the summit of the preputium. As shown in fig. 8 on plate 10 [hoffmani) , the vas deferens, flagellum, and retractor muscle may be so closely pressed together and bent downward at the summit of the preputium that relationship of the muscle is difficult to see clearly unless the parts are separated, as shown in fig. 4, plate 11 {lucidum). All specimens were torn apart to insure accuracy in this statement. Pilsbry also figured the penial complex of Drepanotrema cultratum (Orb.) (plate 76, fig. 10) which is similar to that of lucidum, the vergic sac being but a trifle shorter than the preputium. The flagellum is somewhat more than half as long as the vergic sac. Pilsbry 's figures are the only ones previously published on the anatomy of Drepanotrema. Subfamilies, Genera, and Subgenera — Recent and Fossil 117 Respiratory and Renal Systems. Tlie pseu(l(jl)rancli (P) is a somewhat triangular i)ro('ess in lucidum (plate 11, figs. 1, 2) and anatinuni (plate 9, fig. 3) but in ho)J))iani appears to be narrower and more cylindrical (plate 10, fig. 3). The rectum is very large and the anus discharges just above the base of the pscudobranch. The pneumostome is very large (PS). The kidney of Drepanotrema hoffmani (plate 46, fig. 14) is very long and ribbon-like (15 mm. long). The ureter is very short and curves upward at right angles to the long axis of the kidney. A cross section near the middle (fig. 15) shows the kidney to be much flattened, the lumen wider than high, and the veins flattenecl and elongated in section. The kidney of lucidum is shorter and a section near the middle shows it to be more flattened than hoffmani, the lumen regularly long-ovate and the veins smaller and more 'regular in form (fig. 16). Digestive System, The stomach (plate 48, fig. 11) is pyriform, the pyloris tapering to the intestine, which forms a loop over the oesophagus and another loop around the liver as in other genera of the subfamily. The blind sac is two-thirds as long as the stomach. The buccal sac is similar to that organ in Tropicorbis. The jaw is horseshoe-shaped and is composed of many small plates arranged somewhat as in Planorbis. About seventy plates were counted on a jaw of lucidum (plate 50, fig. 27) and about as many on a jaw of hoffmani (]ilate 50, fig. 26). The radula formula of anatinum. (plate 68, fig. 3) is 18-1-18 with 158 rows of teeth. Center tooth squarish with two long, spade-shaped cusps reaching two-thirds of the way to the lower margin of the base of attach- ment. There is a very small cusp on each side of the center cusps high up on the reflection. Lateral teeth (1-6) very wide, with three long cusps, entocone, mesocone, and ectocone. Above the entocone there is a small additional cusp, and above the ectocone there is another small cusp on the first four laterals and two cusps on the 5th and 6th laterals. The inter- mediate teeth (7-10) are very wide with the three main cusps well-de- veloped and with a small cusp above the entocone and a small interstitial cusp between the mesocone and the ectocone. Above the ectocone there are four small cusps on the outer margin of the teeth. The marginal teeth (11-18) are narrower than the intermediate teeth; there is a long entocone and mesocone with a small cusp above the entocone, three cusps between the entocone and mesocone, and five small cusps on the outer margin of the tooth where the ectocone would normallv be. In lucidum (plate 68, fig. 2), the formula is 28-1-28 with 240 rows of teeth. The center tooth is like that of anatinum except that the large cusps are longer. The lateral and marginal teeth are similar to those of anatinum except that the cusps are longer. In hoffmani (plate 68, fig. 4), the formula is 27-1-27 with 230 rows of teeth. The center tooth is as in lucidum and anatinum. The lateral and marginal teeth are similar to those of the other species figured. Dr. H. B. Baker (1930, p. 50) has examined the radula of ahcnum and says 'The radula and jaw of D. ahenum are also much as in D. lucidum. The radula formula is 30-1-30, with 194 transverse rows. The marginal teeth are slightly broader at the tip of the cusped reflection and may develop two interstitials between the entocone and mesocone.' 118 The MoUuscan Family Planorhidae The radula teeth of Drepanotrema are peculiar in the possession of the small interstitial cusps between the larger cusps. They somewhat resemble the multicuspid teeth of Segmentina, Hippeutis, Intha, etc., to which the genus is also allied by the presence of a fiagellum. The radula of Drepano- trema is very uniform in the shape of the teeth, varying principally in the number of interstitial and accessory small cusps. The formulae, as well as the number of lateral and marginal teeth, vary in the different species. For the above anatomical data, three species have been examined: Drepanotrema anatinum (Orb.) Pueblo Viejo, Puerto Rico, collected by Dr. W. A. Hoffman. Five specimens dissected. Drepanotrema hoffmani F. C. Baker. Isabela, Puerto Rico, collected by Dr. W. A. Hoffman. Eight specimens dissected. Drepanotrema lucidmn (Pfeiffer). Havana, Cuba. Received from Dr. C. G. Aguayo. Five specimens dissected. Geographical Distribution. This genus is found more or less abun- dantly from southern Texas southward through Mexico and Central America to Brazil, Bolivia, and the Argentine Republic. It it also found in many of the West Indies Islands. It is jnirely an American genus and a number of species are known, including some names now considered synonyms. Pilsbry (1934, p. 59) divided the genus into three sections, Drepano- trema proper, Fossidorbis Pilsbry, and Platytaphius Pilsbry. In the writer's opinion, the last section should be regarded as a separate genus until the type has been dissected and its anatomy made known. The other groups divide the genus Drepanotrema into two comprehensive subgenera. Subgenus DREPANOTREIVIA Fischer et Crosse, 1880 Spire on the right side, narrow and deeply sunken; periphery broadly rounded (type Drepanotrema anatinum (Orh. )= Planorbis yzabalensis C. and F. (Pilsbry) Species Considered as Valid. Drepanotrema aruitiniun (Orbigny) Drepanotrema chittyi Aguayo Plate 79, figs. 16-18 Drepanotrema parapseide (Orbigny) Drepanotrema lucidmn (Pfeiffer) Plate Drepanotrema ahenum H. B. Baker 78, figs. 11-13 Drepanotrema castaneonitens (Pils. Drepanotrema hoffniani F. C. Baker and Van.) Plate 78, figs. 14-16 Drepanotrema melleum (Lutz) Subgenus FOSSULORBIS Pilsbry, 1934 Having a wide spiral on the right side, very slightly concave; the periphery from rounded to carinate. Type Drepanotrema cultratum ((Drb.) Pilsbry. Species Considered as Valid. Drepanotrema (Fossidorbis) cultratum Drepanotrema (Fossulorbis) cimex(M.ori- (Orbigny) Plate 78, figs. 17-19 cand) Drepanotrema (Fossulorbis) c. anitense Drepanotrema (Fossulorbis) c. pistiae (Cooper) H. B. Baker Drepanotrema (Fossulorbis) c. duenasi- Drepanotrema (Fossulorbis) depressissi- anum (Tristram) mum (Moricand) Drepanotrema (Fossulorbis) c. labrosum Drepanotrema (Fossulorbis) kermatoide Pilsbry (Orbigny) Drepanotrema (Fossulorbis) c. panuco Drepanotrema (Fossulorbis) sumichrasti Pilsbry (Crosse and Fischer) Remarks. Drepanotrema differs in its genitalia and radula from all other American groups of Planorbidae. By its prostate, the diverticula Subjainilies, Genera, and Subgenera — Recent and Fossil 119 club-^licii)ed aiitl placed in a ^^iiigle row on the sperm duct, it is allied to the subfamily Segmentininae. The jirostate differs from the members of both Planorbinae and Segmentininae in having the diverticula placed di- rectly on the sperm duct instead of on a separate prostate duct. The presence of the fliagellum on the vergic sac places Drepanotrema near the Euroixnm and Asiatic groups Segmentina, Polypylis, Hippeutis, and Intha. The nature of the rachda also indicates relationship with these groups. Although dei)arting from these groups in having the diverticula of the prostate placed directly on the sperm duct, the other characteristics place the genus in the subfamily Segmentininae with little doubt. The form of the shell of typical Drepanotrema bears close resemblance to the edentate Oriental groups of Segmentininae, such as Helicorbis, Intha, and Hippeutis, all having the peculiar embracing whorls so charac- teristic of Segmentina. This feature alone marks the assemblage of genera as of subgeneric solidarity. Genus PARAPLANORBIS Hanna, 1922 Type by original designation Planorbis condoni Hanna 1922. Paraplanorbis H.'Vnna, Univ. Oregon Pub., I, No. 12, p. 4. Type Planorbis (Par a planorbis) condoni Hanna. As section of Planorbis. 1934. Paraplanorbis Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 59. Type Planorbis condoni Hanna. As section or subgenus of Drepanotrema. 1935. Paraplanorbis Hexderson, Non-Marine Moll. N. Amer., p. 245. Fossil. Type Planorbis condoni Hanna. Shell (plate 81, fig. 5) . Whorls rounded on the periphery as in Heli- soma Swainson but aperture not expanded, umbilicus very narrow, and size minute (Hanna, 1922, p. 4, description of subgenus). Hanna's description of the species Planorbis condoni is as follows: 'Shell ultradextral, planorboid, composed of about four and one-half regu- larly increasing whorls; apical cavity a cone of about 120 degrees. Last whorl slightly angulated about the upper margin and descending slightly at the aperture. Lines of growth fine and even, giving the shell a silky luster. Umbilicus deeply rimate 0.51 mm. in diameter. Aperture roughly triangular but rounded on the outer lip; not expanded or thickened but a dejiression both above and below the periphery. Diameter 2.67 nnn.; altitude 0.35 mm.' Geographical and Geological Distribution. Vicinity of Warner Lake, eastern Oregon. Hanna's locality No. 212. Pliocene period. Species Considered as Valid. Paraplanorbis condoni (Hanna), geno- type, is the only species ascribed to this originally monotypic genus. Remarks. This fossil genus is related to Drepanotrema and is con- sidered a section or subgenus of the genus by Pilsbry (1934, p. 59). While the wiiorls are of a clasping or embracing nature, as is usually the case in Drepanotrema and its allies, the spire (left side) appears entirely different, the depression being narrow and the whorls deeply immersed. In view of the difficulty in this family of placing a group in its correct position in the classification by the shell alone, it would seem that the interest of nomen- clature is best served by considering Paraplanorbis a separate genus of Segmentininae related to Drepanotrema. Its geographical location, also, so far removed from the present day distribution of Drepanotrema, is another reason for such procedure. 120 The Molluscan Family Planorbidae Genus PLATYTAPHIUS Pilsbry, 1924 Type by original designation Planorbis heteropleurus Pils. and Van. 1896. Planorbis heteropleurus Pilsbry and Y.an.4tt.\, Proc. Acad. Nat. Sci. Phil., 1896, p. 562, plate 26, figs. 1-3. 1924. Platytaphius Pilsbry, Proc. Acad. Nat. Sci. Phil., 76, p. 51. Type Pla7wrbis heteropleurus P. and V. As section of Planorbis. 1931. Platytaphius Thiele, Handbuch, Teil 2, p. 479. Type Planorbis heteropleurus Pils. and Van. As section of Planorbis. 1934. Platytaphius Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 59. Type Planorbis heteropleurus Pils. and Van. As section of Drcparwtrema. 1934. Platytaphius Henderson and Rodeck, Jour. Pal., VIII, p. 268. Type Planorbis heteropleurus Pils. and Van. As genus. 1935. Platytaphius Henderson, Non-Marine Moll. N. Amer., p. 254. Fossil. Cites two fossil species from Oregon. Shell (plate 79, figs. 10-12). Of medium size, ultradextral, moderately solid, corneous-white, rather opaque, the surface with fine, close growth lines; earlier whorls rather deeply and about equally sunken on the two sides; convex, and strongly angulate or keeled in the middle, on the right side; periphery conspicuously carinated on the left side, which is shallowly vortex-shaped, the whorls nearly flat. Last whorl slightly wider on the right than on the left side. Whorls three and one-half, all visible on both sides, the last wider than the spire. Aperture very oblique, rounded-pentagonal, the right margin produced forward (Pilsbry and Vanatta, 1896, p. 562). There are fine punctations on the embryonic whorls. Animal. At present unknown anatomically. Geographical Distribution. Lake Titicaca, Peru. Geological Distribution. Pliocene to Recent fauna. Species Considered as Valid. Platytaphius heteropleurus (Pilsbry and A'anatta I is the only recognized species. Remarks. In describing this peculiar mollusk, Pilsbry says: 'This remarkable species is totally unlike P. titicacensis Clessin, P. montanus d'Orbigny, and P. andecola d'Orbigny, species already known from this Andean lake. It is most like P. andecola, but much flatter with differently lilaced keels, and in fact, so diverse in characters that no profitable com- parison can be made' (1896, p. 562). In 1924 (p. 51 ) , this species was made the type of a section of Planorbis and in 1934 (p. 59), it was made a sec- tion of the genus Drepanotrema. In a paper by Henderson and Rodeck (1934, p. 268) , the authors state that 'it is so distinct that it might be better to consider it a genus.' With this statement the present author is in com- plete agreement for the general form of the shell is so distinct from that of any other species of Drepanotrema that it does stand quite alone. W^hat its real affinities are can not be known until its anatomy has been investigated. It may belong near Drepanotrema or it may belong elsewhere. Henderson and Rodeck ( 1934, p. 268) have associated two extinct molluscan species from the Pliocene of Oregon with Platytaphius. The localities are sixteen miles southwest of Vale, Oregon. This locality is so far removed from Lake Titicaca, in Peru (more than 5000 miles), that it would seem impossible for species of any group without intermediate habi- tats to become established so far apart. Yet the two species from Oregon correspond fairly well with the diagnosis of the genus Platytaphius. Ad- Subjmnilies, Genera, and Subgenera — Recent and Fossil 121 ditional si)ecies, recent or fossil, may be found somewhere between these extreme points. At present there seems no alternative but to include the Oregon fossils in Platytaphiiis, since no diagnosis could be made that would include the one and exclude the other. The two species of fossils from Oregon are Platytaphius vialheurcnHiH and P. 7nilleri Henderson and Rodeck, figured on j:)late 37 of the publication cited, figs. 6, a, b, c and 9, a, b, c. Genus ACRORBIS Odhner, 1937 Type by original designation Acrorbis petricola Odhner 1937. Acrorbis Odhner, Archiv. fiir Zoologi, Band 29B, No. 14, ]). 1. Nov. 9, 1937. Type Acrorbis petricola Odhner. As genus. 1938. Acrorbis Pilsbry, Nautilus, LI, p. 107 (review). Shell (plate 72, figs. 1-3). Ultradextral, very small, thin, but firm, of circular form, with elevated spire, shell covered with a shining cuticle, openly umbilicatc; whorls slowly increasing, arched, high, simple; aperture very oblique, broadly ovate; lips simple, very thin because of the lack of lime in the mouth-building; shell brown, dark and reddish above, under- side more grayish; apex deep brown, globular, smooth, the following whorls with very weak spiral lines. Height of aperture same as height of whorl. Height 1.5 mm.; diameter 2 mm. (translated from Odhner). Animal (plate 72, figs. 5, 6). Gray, the upper surface of the mantle flecked with black. The head is darker gray and neck blackish. The foot is broadly o\'al with thin borders and without any furrows on the sides. The tentacles are narrow, when fully extended, on the end obliciuely truncated. The eyes are on the inner side of the base of the tentacles. The left tentacle differs from the right tentacle in being bifid at the end. The head is sharply pigmented between the eyes. ANATOMICAL CHARACTERISTICS PLATE 72 GENITALIA. Male Organs (fig. 10). No seminal vesicle is show^n in the figure or mentioned in the description. The prostate is almost as long as the uterus and oviduct and has eight large diverticula in a single series. Neither description nor figure indicates the presence of a separate prostate duct. The vas deferens (v) is a long and narrow tube. The penial complex (fig. 9) is elongated, the preputium, about one-third of the entire length, merging into the vergic sac without marked constriction between these sacs. There is a wide retractor muscle (rp) which appears to be attached about midway of the length of the vergic sac. Above the vergic sac there is a wide flagellum less than half as long as the vergic sac. Internally there is a long, tube-like verge and a diaphragm of fleshy ridge separating the preputium from the vergic sac. The upper end of the flagellum is said to liave two cavities, one on each side of a central tube (fig. 9, a). Female Organs (fig. 10). The spermatheca (b) is large and globular and is attached to the short, narrow vagina by a very short duct about one-third the length of the diameter of the spermatheca. The uterus (u) is at first as narrow as the vagina, but swells to several times this diameter posteriorly where it joins the nidamental gland. The oviduct is not shown clearly but evidently narrows to the point of junction with the ovisperm duct. The albumen gland is not figured. 122 The Molluscau Family Pknwrbidae Hermaphrodite Organs. The ovotcstis (go) is few-lobcd, consisting of but five diverticula, which are smaller than the diverticula of the prostate. It is not stated whether the lobes of the ovotestis are in a single or a double row. The ovisperm duct (od) is almost as long as the uterus and oviduct combined and is a very narrow tube. Respiratory System. The pseudobranch (figs. 5, 6, k) is shown as bifid at the extremity. It is a narrow projection about twice as long as wide, and probably bears the anal outlet as in other Planorbidae. The kidney (fig. 5, n) is long and narrow without a superposed ridge. Digestive System (fig. 8). There is a long and narrow oesophagus, an ovate stomach with a short pyloris and a very short blind sac (caecum, c), and a long intestine which makes a loop around the stomach and another around the liver, extending forward in the rectum (r) to the outlet near the pseudobranch. The buccal sac (fig. 7) is elongated, wide at the posterior end and much elongated at the anterior end. There is an unusually long radula sac (t) which forms a narrow tube as long as the whole radula sac. The salivary glands (s) are short, entering the radula sac by a fine tube. The jaw is said to be like that of Parapholyx iPompholycodea) . The radula (fig. 4) formula is not given but sixteen teeth show in one row in the figure which would make the formula 16-1-16. The center tooth has two wide cusps which do not reach the lower margin of the base of attachment. The laterals are sciuarish with a long, spade-shaped mesocone reaching the lower margin of the base of attachment, and a short entocone and ectocone about half as long as the mesocone. The intermediate teeth have the cusps more nearly equal in size. The marginals appear wide and low, the entocone and ectocone splitting into two smaller cusps. The information concerning this genus has been drawn entirely from the original paper and figures bv Oclhner. His figures are reproduced on plate 72. Geographical Distribution. State of Santa Catharina, Brazil. It lives in damp moss on rocks over which water trickles. Species Considered as Valid. Acrorbis; petricola Odhner, type of the genus, is tlie only species recognized. Remarks. Acroi^bis is apparently a very distinct group of South Ameri- can Alollusca. It is not related to Carinijex or Parapholyx {Pompholy- codea) as indicated by Odhner, these two genera belonging to another subfamily, the Helisomatinae, in which there is a penial gland in the male comjilex. It scarcely appears to belong with Choanomphalus. It is also com- pared with Neoplanorbis Pilsbry, but that group is referable to the family Ancylidae, not Planorbidae. Pilsbry has stated (1938, p. 107) that it is related to either Tropicorbis or Drepanotrema. The presence of a fiagellum indicates a relationship with Drepanotrema and the few diverticula of the prostate in a single series indicates the same relationship, although the diverticula are more crowded than has been observed in species of Drepanotrema examined. Acrorbis differs from Drepanotrema in the wide form of the fiagellum, the shape of the penial complex, wide for the whole length with no differentiation between preputium and vergic sac, the globular spermatheca on a very short duct, and the helicoid form of the shell, quite different from the Subfamilies, Genera, and Subgenem — -Recent and Fossil 123 overlapping whorls of Drcpanotrona. The very long radula sac is also a characteristic feature of the anatomy. The radula appears very different from that of Drepanotrema (see plate 68) because of the apparent absence of interstitial cusps between the larger cusps. These might have been present but overlooked because of tiic small size of the radula teeth. The general shape of the mesocone in Odhncr's figure (4) is suggestive of the same cusp in Drepanotrema, but the ectocone and entocone are much shorter. The radula is markedly dif- ferent from that of Tropicorbis. Aa^orbis, therefore, appears to be another one of the peculiar groups of South American Planorbidae, related to Drepanotrema, but distinct by both shell and anatomy. Subfamily HELISOMATINAE F. C. Baker, 1928 Prostate diverticula compound or multiple, consisting of a basal stem with branches grouping around a short prostate duct which is in intimate contact with the sperm duct. In cross section, the prostate exhibits a fan- like design. A penial gland is nearly always present with an external duct of greater or lesser length. The kidney is usually heavily ridged. The jaws are sim})le, of three pieces, a superior and two lateral jaws. Type genus Helisoma Swainson. The groups referred to this subfamily are noted below. With one penial retractor muscle: Helisoma and subgenera Seminolina, Picr- osoma and Planorbella. With two penial retractor muscles: Carinifex and Parapholyx. Without penial gland duct: Planorbarius. The fossil groups Vorticifex, Perrinilla, and Pompholopsis are included in this subfamily because of likeness of shell to Carinijex or Parapholyx. With the exception of Planorbarius, which appears to have character- istics admitting it to this group, the subfamily is wholly American and is perhaps the most important planorbid element in the North American molluscan fauna. It is widespread throughout the northern part of North America and the species are numerous. Genus HELISO:VIA Swainson, 1840 Type by original designation Planorbis bicarinatus Sowerby (= Planorbis bicarinatits Say = Planorbis anceps Menke) 1840. Helisoma Sw.\ixsoN, Treat. Malac, p. 337. Type Planorbis bicarinatus Sowb. As subgenus. 1846. Helisoma Herrm.^nnsen, Ind. Gen. Mai. Prim., I, p. 516. Tj^pe Planorbis bicarinatus Say. As subgenus. 1865. Helisoma Binney, L. and FW. Sh. X. A., II, p. 112. No type cited. As subgenus. 1870. Helisoma Dall, Ann. N. Y. Lye. N. H., IX, p. 351. Type Planorbis bicari- natus Sowb. As subgenus of Planorbis. 1872. Helisoma Tryon, Mon. FW. Univ. Moll. U. S., pp. 188, 198. No type cited. As subgenus. 1880. Helisoma Fischer and Crosse, Moll. Terr. Fluv. Mexico et Guat., II, p. 60. As subgenus. 1884. Helisoma Tryon, S. and S. Conch., Ill, p. 106. Type Planorbis bicarinatus Say. As subgenus. 1886. Helisoma Cle.ssix, Syst. Conch., XVII. i). 33. Tyjie Pl((uurbi.'< bicarinatus S:iy. As subgenus. 124 The Molluscan Family Planorhidae 1899. HeUsoma Martens, Biol. Cent. Amer., Moll., p. 381. No type cited but includes Pierosoma. As subgenus. 1902. HeUsoma F. C. Baker, Moll. Chi. Area, II, p. 287. No type cited. As subgenus. 1905. HeUsoma Dall, Alaska Moll., pp. 81, 84. Type Planorbis bicarinatus Sowb. As subgenus. 1912. HeUsoma Hannibal, Proc. Mai. Soc. London, X, p. 157. Type Planorbis antrosus Conrad. As genus. 1918. HeUsoma Walker, Miscel. Pub., Mus. Zool., Univ. Mich., No. 6, p. 11. Type Plaiiorbis bicarinatus Say. As subgenus. 1921. HeUsoma Germain, Rec. Ind. Mus., XXI, pp. 6, 64. Type Planorbis carinatus Say. As subgenus. 1923. HeUsoma Wenz, Fossil. Cat., Pars 22, p. 1522. Genotype HeUsoma bicarinata (Sowb.). As genus. 1926. HeUsoma F. C. Baker. Trans. Wis. Acad. Arts and Sci., XXII, p. 201. Type Planorbi^s bicarinatus Sowb. As genus. 1928. HeUsoma F. C. Baker, Fresh-water Moll. Wis., I, p. 311. Type Planorbis bicarinatus Sowb. As genus. 1929. HeUsoma Chamberlin and Jones, Bull. Univ. Utah, Biol. Ser., No. 1, p. 145. Genotype Planorbis bicarinatus Sowb. As genus. 1930. HeUsoma H. B. Baker, Occ. Papers, Mus. Zool., Univ. Mich., No. 210, p. 43. Planorbis bicarinatus Say. As genus. 1931. HeUsoma F. C. Baker, Proc. Zool. Soc. London, p. 584. Type Planorbis bi- carinatus Sowb. As genus. 1931. HeUsoma Thiele, Handbuch, Teil 2, p. 479. Type Planorbis bicarinatus Say. As section of Planorbis. 1934. HeUsoma Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 47. Type Planorbis bica- rinatus Say. As genus. Subgenus HELISOMA SS. Type Planorbis anceps Menke Shell (plate 80, figs. 1-6). Large, sinistral, of comparatively few whorls which rapidly increase in size, carinated; spire and umbilicus funicular; aperture expanded, outer lip thickened. Animal. Yellowish or brownish, flecked with whitish; there are s]5ots of color near the eyes and between the tentacles, and the mantle is spotted with dark mottling, especially over the kidney. The tentacles are long and filiform and the velar area is notably developed. The shell is carried almost perpendicularlv. ANATOMICAL CHARACTERISTICS PLATE 23. HeUsoma anceps (Menke) GENITALIA. Male Organs (fig. 11). Seminal vesicle (SV) short (about 1 mm. long) and widely rounded, composed of many small follicles. An- terior to the seminal vesicle, for the space of 2.5 mm., the ovisperm duct is bordered by many small follicles which may represent a portion of the seminal vesicle (SO). The sperm duct (SPD) is about 6 mm. long and is of wide diameter, somewhat sausage-shaped, the tube about 0.3 mm. in diametei'. The prostate (PRS) is ovate in shape, about 2.5 mm. long, 1 mm. wide and less than 1 mm. in height. It is composed of numerous diver- ticula forming a pavement-like pattern when viewed externally. In section (fig. 9) the prostate is fan-shaped, composed of six to eight diverticula each of which is branched two to four times toward the distal end. The prostate is placed on a short prostate duct which unites with the sperm duct to form the vas deferens (plate 22, fig. 12) . The vas deferens (VD) Subfamilies, Genera, and Subgenera — Recent and Fossil 125 is about 14 mm. long, somewhat smaller in diameter than the sperm duct. It is still further diminished in diameter as it emerges from the muscular tissue to enter the jienial complex (plate 23, fig. 3, VD). Near the summit of the vergic sac the vas deferens enlarges to form an epiphallus (EPI). Tlic penial comjilex (plate 23, fig. 3) is a short, somewhat pyriform organ about 4 mm. long. The preputium (PR) is very wide (1.7 mm.) and about 2.5 mm. long. The vergic sac (VS) is somewhat bullet-shaped, 1.5 mm. long and 1 mm. wide. There is no marked constriction between the preputium and the vergic sac. There is a wide retractor muscle (RM) attached to the preputium just above the male opening. On the right side of the preputium there is a group of supporting muscles (S^I). This group may form a wide, solid band or it may be broken up into ten or twehT smaller muscular bands. The supporting muscles are attached to the roof of the mantle cavity. There is a short (2 mm. long), narrow, external tube or duct (DC) on the outside of the preputium and adherent thereto. This penial duct tapers to half its diameter as it enters the junction of the prejiutium with the vergic sac. Internally (fig. 2) the penial comjilcx shows two cavities, an upper vergic space and a lower preputial space, separated by a muscular ring or diaphragm (D) which is capable of great contraction and expansion (see fig. 5). In the preputial space there is one large, vertical fold or pi- laster (PL) and several smaller vertical ridges. Attached to the wall of the preputium at the upper end of the large pilaster is a rounded, cup-shaped penial gland (GL). In section (fig. 1) this gland is seen to have the cup- shaped, bulbous termination divided into two parts, an upper portion with smooth or only slightly developed vertical fokls (OC) and a lower portion (LC) lined with heavy vertical folds (GF). The floor of this cup is covered with pavement-like folds, from which a narrow duct (DC) extends through the neck of the gland and emerges through the bodv wall of the preputium and becomes the external penial duct. A section through the region at the junction of the two spaces (fig. 6) shows the relationship of the muscular ring or diaphragm (D) to the gland duct, the latter penetrating the thick wall of the lower portion of the vergic sac and opening into this cavity just above the diaphragm. In fig. 11, plate 22, the outer cup of the gland is turned back to expose more fully the folds of the inner cuji (Helisoma an reps percarinatian) . Tlie A'orgc (plate 23, fig. 2, V) is normally short and wide and tapers abruiitlv to a narrow point. In fig. 1 on plate 22 {Helisoma anceps latch- fordi) it is shown well-extended, exhibiting an elongated, cylindrical form, the supporting muscles (MS) plainly indicated at the upper end near the top of the vergic sac. The enlarged epiphallus is also indicated. At the terminal end of the verge the seminal opening is placed in the center of the organ with a small, sharp appendage or papilla extending slightly below the end of the verge. In fig. 10 on plate 22, the end of the verge is shown with this feature enlarged to show the pointed pajiilla and the centrally located seminal opening. The penial complex may assume a number of shapes, depending uj^on the sexual condition of the animal. Often it is seen as shown in fig. 8, plate 23, the penial gland pushed upward causing the com]ilex to assume a bilobed aspect. The penial gland and the verge may sometimes be seen l^rotruding from the male ojiening and lying on the neck of the animal. 126 The Molluscan Family Planorhidae The verge is often extended into the preputial cavity as shown in figs. 2, 3, and 4 on pLate 22. Female Organs (plate 23, fig. 11). The spermatheca (S) and its duct are 5 mm. long, the spermatheca elongated, sausage-shaped and slightly less in length than the duct, which is rather wide and enlarged as it enters the long (1.5 mm.) and narrow vagina. The uterus (U) is about 5 mm. long, widening upward to the nidamental gland (NG), which is about 2 mm. long and 1 mm. wide. The oviduct (OD) is about 4 mm. long and 0.3 mm. in diameter. There is a large carrefour (CD into which the small, narrow duct of the albumen gland enters (DA). The albumen gland (fig. 7) is squarish in form, about 2.5 mm. in diameter and is composed of small follicles. Near the albumen duct the lobules are much larger than in the body of the gland. A depression crosses the gland on the under side mark- ing the space occupied by the intestine. Hermaphrodite Organs (fig. 11). The ovotestis (OT) consists of many rows of club-shaped diverticula having a pavement-like appearance from the surface of the gland. In section (fig. 10), the ovotestis is seen to be composed of about a dozen diverticula extending fan- wise from the ovisperm duct. The free portion of the ovisperm duct (SO) is somewhat shorter, between the seminal vesicle and the ovotestis, than between the seminal vesicle and the oviduct, but about 1 mm. in both regions. The larger portion of the ovisperm duct is occupied by the seminal vesicle. The genitalia of the races of Helisoma anceps, as far as they have been examined, are remarkably uniform. In specimens of Helisoma anceps percarinatum from Douglas Lake, Michigan, there was some variation in the form of the retractor muscle, this being often divided into several branches toward the columella muscle (plate 22, figs. 2, 3, 4). In one specimen (fig. 4) there were two muscles, an abnormal condition. Respiratory and Renal Systems. The pseudobranch (plate 23, fig. 4, P) is squarish in shape, rounded below, pad-like, with a distinct ridge passing down the center from the rectal region. The pseudobranch is 2 mm. wide and about 1 mm. high. The rectum is very wide and there is an irregular crest or ridge extending down the center (R). This ridge extends backward on the rectum about a cjuarter of a whorl. It narrows notably as it nears the anal end of the rectum. The pneumostome (PS) is not notably large. The kidney (plate 44, fig. 1) is 7 mm. long and 2 mm. wide at the upper (pericardial) part, tapering to about 1 mm. wide at the lower part. The ureter is less than 1 mm. long and is sharply reflexed parallel to the long axis of the kidney. The pericardium is nearly 2 mm. long and 1 mm. wide. There is a large and conspicuous superposed ridge extending from just below the pericardium to the urethral portion of the kidney and going beyond the kidney almost to the mantle margin. In cross section (fig. 7), this ridge, at the i)oint in fig. 1 marked by the arrow, is seen to form a long fold which extends over the kidney causing it to appear rounded in a ventral view of the kidney, as shown in fig. 1. The lumen is regularly rounded and the two blood vessels appear on each side at the lower part of the section. A small ridge to the left of the lumen is shown in the figure. This ridge in the mantle is present in all species of the family. A cross section of the kidney of Helisoma anceps latchfordi (fig. 8), taken at about the middle of the kidnev, shows a less extensive ridge (RK) Subfamilies, Genera, and Subgenera — Recent and Fossil 127 but is otherwise similar to typical anceps. The form of the section may vary when taken from different parts of the kidney, as is shown in several sj^ecies of Helisoina. Digestive System. The stomach is bulbous and tapers into the pyloris. The intestine loops around the stomach, passes over the oesophagus, turns backward in a long loop around the liver and then runs forward to the l^seudobranch in the form of the rectum. The general form is like that of HeUsomn trivolvis shown in fig. 1 on plate 48. The buccal sac is short-ovate. The salivary glands are narrow and about twice as long as the buccal sac. They are joined behind. The jaw (plate 49, fig. 1). There is one wide, low, arched superior jaw (about 1 mm. wide) and two narrow, ribbon-like lateral jaws somewhat longer than the superior jaw. The superior jaw is finely striated on its anterior face. The radula has the variable formula 22-1-22 to 30-1-30, with 150 to 193 rows of teeth. A radula from specimens from Maple River, Michigan, is figured on plate 53, fig. 1. The center tooth is squarish with two short, wide cusps. The lateral teeth (1-5) have a squarish reflection which ex- tends well below the lower margin of the base of attachment. The cusps are spade-shaped, the mesocone the longest and the ectocone the shortest. The ectocone of the fourth tooth is split into four small cusps. The inter- mediate teeth (6-7) are narrower than the lateral teeth, the base of at- tachment very short. The entocone is broken up into two or three small cusps and several small cusps appear on the outer edge of the tooth above the ectocone. The marginal teeth (8-14) are much narrower, this feature increasing toward the outer margin of the membrane where the teeth are ^'ery long and narrow (14). In the marginal teeth the entocone is broken up into fine serrations numbering from five to ten cusps, the number in- creasing in the outer teeth (compare 8 and 14). The mesocone becomes somewhat smaller but is not modified. The ectocone is distinct in the 8th tooth with three small cusps above it. From the 10th tooth this area changes to small serrations five to six in number. The outer marginal teeth appear like a saw, wdth one large tooth (the mesocone) in the center (see 14). The extreme outer marginals are vestigial. The radulae of anceps and its races vary considerably, principally in the numerical formulae, but also in the number and position of the cusps. The table below indicates the extent of this variation. The columns are all as follows, reading from left to right: Locality, formula, lateral teeth, intermediate teeth, plate, and figure. Helisoma anceps (Menke). Maple River, Michigan 23-1-23 to 24-1-24 1-5 6-7 Plate 53, fig. 1 I'nionville, Conneotiout 23-1-23 to 25-1-25 1-5 6-7 Plate 53, fig. 3 ChautaiKiua Lake, New York 22-1-22 to 25-1-25 1-7 8-9 Plate 53, fig. 2 Moo^ie Ear Creek, Wisconsin 26-1-26 to 27-1-27 1-6 7-9 Cleveland, Oneida L., New York 25-1-25 to 27-1-27 1-6 7-S There are 150 to 160 rows of teeth. HcUsoinn anceps sayi F. C. Baker. Bayfield, Wisconsin 27-1-27 to 27-1-27 1-5 6-7 Plate 53, fig. 4 Helisonta anceps percarinatuni (Walker). Douglas Lake, Michigan 27-1-27 to 30-1-30 1-8 9-10 Plate 54, fig. 1 There are 193 rows of teeth. 128 The MoUuscan Family Planorbidae Helisoma anccps royalense (Walker). Bamiji Lake, Ontario 25-1-25 to 27-1-27 1-S 9 Plate 54, fig. 2 There are 170 rows of teeth. Helisoma anceps cahni F. C. Baker. Big Muskallonge Lake, Ontario 27-1-27 to 27-1-27 1-6 7-9 Plate 54, fig. 3 There are 160 rows of teeth. Helisoma anceps latchfordi (Pilsbry). Meach Lake, Quebec 27-1-27 to 30-1-30 1-6 7-9 Plate 54, fig. 4 There are 190 rows of teeth. For the above data more than forty siiecimens have been examined. In general form of teetli, there is complete agreement in all radulac examined, both from the same locality and from different places. The formulae vary and along with this variation, the numbers of lateral and intermediate teeth likewise vary. Abnormal teeth arc connnon in radulae of Heluoma anceps. In a speci- men from Maple River, Michigan, the fourth lateral of the fifteenth row had the ectocone broken up into four small cusps (plate 53, fig. 1). In a specimen from Chautauqua Lake, New York, the center tooth of the 118th row was broken up into three small cusps and one large cusp. In the first lateral of the same row, the entocone was split into two small cusps (plate 53, fig. 2). In a specimen from Unionville, Connecticut, the fifth lateral of the ninetieth row had a split ectocone. The 8th and 9th teeth of this row had the intermediate in unusual form. This row shows the shape of the teeth on the left side of the membrane (plate 53, fig. 3, lower row). In the races of anceps, the same tendency to form abnormal teeth is observed. A specimen of saiji from Bayfield, Wisconsin, had the center tooth of the seventy-fifth row with three small cusps on the left side and one small cusp on the right side of a central cusp. All of the laterals in this row had the entocone broken up into two small cusps (plate 53, fig. 4, lower right row). In a radula of percarinahmi from Douglas Lake, Michi- gan, the first and second laterals of the 100th row had the entocone split into two smaller cusps (plate 54, fig. 1, lower row). A specimen of latch- fordi, in the sixtieth row, had the central tooth with an extra cusp on each side of two smaller central cusps (plate 54, fig. 4, 60). All of the teeth of this race examined had two very small denticulations on the edge of the reflection above the ectocones (plate 54, fig. 4). Geographical Distribution. The species of typical Helisoma inhabit North America from British America (Hudsons Bay) southward to Lou- isiana and Alabama and westward to the Rocky INIountains. Species Considered as Valid. This, the typical subgenus of the genus Helisoma, contains one sj^ecies with many races and a second species with two recognizable races. Helisoma anceps anceps (Menke) 1830 Helisoma anceps unicarinatum (Halde- (=^ Planorhis bicarinatus Say 1819 man) (preoccupied), P. antrosus Conrad, Helisoma anccps striatum (F. C. Baker) 1834) Helisoma anceps cahni F. C. Baker Helisoma anceps sayi F. C. Baker Helisoma anceps latchfordi (Pilsbry) Helisoma anceps shellense F. C. Baker Helisoma anceps portagensis (F. C. Helisoma anceps percarinatum (Walker) Baker) Helisom.a anceps royalense (Walker) Helisoma anceps aroostookense (Pilsbry) Helisoma anceps ruski F. C. Baker Helisoma eucosmium (Bartsch) Helisoma anceps jordanense (Winslow) Helisoma eucosmium vaughani (Bartsch) Subfa/nilies, Genera, and Subgenera — Recent and Fossil 129 Geological Distribution. Miocene?, Pliocene to Recent fauna. Remarks. Typical Hclisotua is characterized by a short and wide, some- what bulbous penial complex without a notable constriction between the preputium and the vergic sac. There is a cup-shaped penial gland with a short, narrow, almost straight penial gland duct. The prostate and ovo- testis are made up of many small diverticula radiating from a duct in fan- like i)attern when seen in cross section. Helisoma differs from Pierosoma in its shorter penial gland duct, wider and shorter vergic sac, and generally- different penial complex. From Seminolina, which resembles Helisoma in its short i)enial gland duct, it differs by its shorter duct. The radular teeth also differ from Seminolina in having the cusps sharply aculeate instead of rounded. The' shell of Helisoma is also quite different from Pierosoma and Seminolina in its general bicarinate form with the spire and umbilicus both deeply concave. As a subgeneric name, Helisoma has been known in molluscan litera- ture for many years. Binney (1865, p. 112), Tryon (1870, p. 188), and Dall (1905, p. 81) cite the name, using, however, onlv characteristics of the shell for its distinction. In 1926 (p. 201) and in 1928 (I, p. 311), Baker elevated the group to generic rank, basing the distinction on the peculiar genital complex of the male organ. In 1931 (p. 584), the genus was diag- nosed by Baker and the distinctions of the genitalia described and figured. Authors generally have misquoted the type of the genus. The Planorbis bicarinatiis of Sowerby, while with little doubt the same as Planorbis bi- carinatus Say, has nothing to do with Say's species and Sowerby was probably not aware that there was another bicarinatus. Dall (1905, p. 84) cited the type as Planorbis bicarinatus (Say) Sowerby, which is incorrect, although the type is correctly cited on page 81. The citation of Planorbis bicarinatus Say, as has been made by some authors, is also incorrect. Say's species dates from 1817, Sowerby 's from 1824. A careful study of Sowerby's description and his two figures on plate clxxvii (fig. 4) leaves little doubt about the unity of his species with that of Say. Binney (1865, p. 124) thought it might be Planorbis campanulatus Say, but both figures and description point to bicarinatus. Binney based his opinion evidently on the lower fig. 4 of the plate, which is not clear, and might be mistaken for cam'panulatus. There is little question about the upper figure being intended for bicarinatus. Unfortunately this appro- priate name can not be used, as it is preoccupied for a Paris Basin fossil. Conrad's Planorbis antrosus 1834 has been used in place of bicarinatus, but ]\Ienke's name precedes this by four years and must be accepted. Regarding the name Helisoma, it is a Greek noun in the neuter gender and all specific names must, of course, also be neuter (H. B. Baker, 1930, p. 139). Subgenus SEAIINOLINA Pilsbry, 1934 Type by original designation Helisoma scalare (JajO 1870. Amcria Dall, Ann. N. Y. Lye. X. H., IX, ]>. 356. Example Phym scalaris Jay (non H. and A. Adams, 1855). 1886. Thomsnnia Axcey, Le Xaturali.>hohjx cffuM, klamnthcnsis F. C. Baker) GENITALIA. Male Organs (fig. 3). Seminal vesicle (SV) about 4 mm. long, swollen, with many small vesicles projecting from the other- wise smooth surface. The sju^rm duct (SPD) is about 3 mm. long and of large diameter (0.4 mm. L The prostate (PRS) is long (3.5 mm.) and wide and is composed of many small diverticula. In section (fig. 4), these di- verticula are seen to be composed of about a dozen irregular follicles linked together like sausages. From the outside of the prostate, these diverticula appear to be covered with small tubercles irregularly placed. These follicles enter the sperm duct at a common center, shown at X in the figure. The vas deferens is about half the diameter of the sperm duct and is 11 mm. long. The penial complex (fig. 7) is sac-like and is nearly 4 mm. in length. The preputium is 1 mm. wide and occupies most of the length of the penial complex. The vergic sac (VS) is 1 mm. long and 0.7 mm. wide. There is only a slight constriction between the prejiutium and the vergic sac. The penial gland duct is relatively short (about 1.5 mm. long) and rather thick. It extends from the i)reputium near its upper third and enters the vergic sac at the constricted area. The portion of the duct entering the vergic sac and the preputium is very small and narrow, the duct swelling greatly in diameter on the surface of the preputium. There are two sets of retractor muscles, each set consisting of two main branches which sub- divide several times at the penial sac insertions and at the connections in the columella muscle. All insertions are on the preputium, none on the vergic sac. There are several narrow supporting muscles (SAI) attached to the preputium. Internally (fig. 9) , the preputium has two large, fleshy folds or pilasters (PL). There is a mucii elongated, cylindrical penial gland (1.7 mm. long) which resembles a pipe-stem, with a cup-shaped or bowl-shaped gland (about 0.5 mm. in diameter) placed at the lower end (GL). The duct (DC and X) enters the cylindrical portion of the gland and extends through this stem-like portion, then enters the bowl-like cup of the gland where it is enlarged into a bulb-like body (fig. 11, X). The cup-shaped gland resembles the bowl of a pipe. In section (fig. 11), the cup shows a shallow area at the top and the sides are lined with wide, thick folds (GF). The bottom of the bowl-like cup is covered with small follicles which are Suhfamilies, Genera, and Subgenera — Recent and Fossil 163 placed at the upper end of the rounded enlargement of the penial gland duct. The right pilaster is attached to the gland at its upper end, curving toward the gland beneath the gland duct. There is a thick ring or diaphragm (D) which separates the cavity of the preputium from the vergic cavity. This diaphragm has a circular canal into which the upper end of the penial gland duct, which is greatly diminished in diameter, enters. This feature is shown in fig. 10. The verge (V) is narrowly pyriform, tapering to a point at its lower end. The sperm canal extends through the center of the verge and has a central outlet (fig. 121. A large nerve and blood vessel supply the penial complex (fig. 8). Female Organs (fig. 3). The spermatheca (S) is large and egg-shaped, almost globular. It is connected with the short, narrow vagina (VG) by a narrow duct shorter than the length of the spermatheca (SD). The uterus (U) is narrow as it passes upward from the vagina but increases abruptly in diameter to three times the width of that region, combining with the nidamental gland. This region is concealed by the prostate in fig. 3. The oviduct (OD) contracts in diameter to form a sac-like organ of small diameter. There is a large carrefour (CF). The albumen gland (AD is 4 mm. long and is longer than wide. The duct of this gland is long (0.5 mm.). Hermaphrodite Organs. The ovotestis (OT) is long and sac-like and is composed of several club-shaped diverticula. A section near the middle of the ovotestis (fig. 5) shows eight rather long diverticula, the longest follicles being in the center. A section near the posterior end (fig. 6) shows six diverticula in less fan-like pattern. Sections from the middle to the anterior end show eight diverticula all in fan-shaped pattern, but sections made toward the posterior end show but six diverticula which are more or less irregularly arranged. The ovisperm duct is very short in the portion be- tween the ovotestis and the seminal vesicle. The free portion near the oviduct is somewhat longer. The seminal vesicle (SV) occupies about two- thirds of the length of the ovisperm duct. The genitalia of Parapholijx effusa diagonaUs Henderson, also dis- sected, do not differ from the figures and descriptions herein presented. In 1870, Dall dissected Pompholyx soUda and published descrii-)tions and several figures of the genitalia. These are not in sufficient detail and embrace some errors, such as the presence of a distinct testicle on the male system. This might have been the albumen gland. As far as can be seen, the anatomy of solida is similar to that of the species personally examined and herein figured. Respiratory and Renal Systems. The pseudobranch (fig. 2) is a tri- angular appendage extending from the rectal region. There is a distinct ridge extending over the rectum in a broad curve, ending above the anus. The kidney (plate 46, fig. 1) is short and wide (about 3 mm. long and 1 mm. wide) ; the ureter is large and sharply refiexed. directed upward into the mantle cavity. The pericardium is also large (about 1 mm. long). A cross section of the kidney near the middle (fig. 2) shows a much flattened form with a wide lumen, the veins ovate and flattened, and placed at the lower lateral sides of the lumen. There is no ridge and the section re- sembles that of Carinifex. Digestive System. The stomach is like that of Carinifex and essen- tially as described by Dall for Pompholyx solida. The oesophagus is short 164 The Molluscan Family Planorhidae and is enlarged just behind the buccal sac. The salivary glands form a loop. The buccal sac is short, high and pyriform, as in Carinifex. The jaws are three in number, differing markedly from the single horse- shoe-shaped jaw of Carinifex. The superior jaw is low and about three times as wide as high. The side jaws are as in Helisoma. The face of the superior jaw is striated vertically. There is little difference between the jaws of klamathensis and diagonalis. Dall says there are no accessory plates (side jaws) but they occurred in all specimens personally examined. The jaw figured by Dall (his plate 2, fig. 11a) is different from the jaws found in the two races examined. The radula of P. effusa klniitathoi.'iis (plate 65, fig. 3) has a squarish center tooth, the bicuspid reflection not reaching the lower margin of the base of attachment. The lateral teeth (1-8) are scjuarish and tricusi)id, all cusps being sharp and spade-shaped. The intermediate teeth (9-11) are narrow, the ectocone splitting into two sharp cusps as long as, or nearly as long as, the mesocone. There are two small cusps on the outer border of the tooth, above the ectocone. The marginal teeth (13-15) are narrow, the entocone with four to five small cusps, the ectoconic region with three cusps. The outer marginal teeth (16-19) are very narrow and are simply serrated on the ectoconic side, there being no division into entocone, meso- cone, and ectocone. Ball's figure of the radula of solida (his plate 2, fig. 9) shows the lateral teeth with a rounded mesocone and all cusps appear too blunt. The marginal teeth are too wide and the small cus])s are not shown. Radula Formulae of Paraphnhjx Species Formula Locality Roirs Collector klamathensis 19-1-19 Klamath Lake, Oregon 125 J. Henderson diagojialis 21-1-21 Crater Lake, Oregon 100-114 J. Henderson solida 22-1-22 White Pine, Nevada 150 Ball's paper The following material has been examined for the anatomical data contained in this work. P. effusa klamathensis from outlet of Upper Klamath Lake, Oregon, eight si)ecimens examined. P. effusa diagonalis from Crater Lake, Oregon, eight specimens examined. Both lots collected by J. Henderson. Geographical Distribution. Parapholyx is purely an American genus confined to the west coast of America from Washington southward to Cali- fornia and eastward to Nevada. Pompholyx leana H. and A. Adams was described from 'West Columbia,' but no specimen of this genus has been seen from British Columbia and it is very doubtful that the genus is found north of the United States. A number of species and races have been described and the same opinion expressed for the division of Carinifex may also ap]^ly to this genus. Species Considered as Valid. Parapholyx ejjusa effusa (Lea) Parapholyx nevadensis J. Henderson Parapholyx ejjusa coHata (Hemphill) Parapholyx mailliardi Hanna Parapholyx ejfusa diagonalis Parapholyx solida solida (Dall) J. Henderson Parapholyx solida optima (Pilsbry) Parapholyx ejfusa klamathensis F. C. Parapholyx leana (H. and A. Adams) Baker Species practically unknown Geological Distribution. Parapholyx is certainly known from the Pliocene to the Recent fauna. It may occur in earlier deposits. One extinct Suhfaniilies, Genera, and Subgenera — Recent and Fossil 165 species is known, Parapholy.v packardi Hanna, from Warner Lake deposits in eastern Oregon. Remarks. Parapholyx is a very distinct genus both in shell and anat- omy. The shell is depressed and almost neritaeform. The anatomy is pe- culiar in several respects. The prostate is not composed of distinct club- shaped diverticula, but of small gland-like bodies arranged like a string of sausages. The penial gland is not a short, cup-shaped organ, as in Carinifex, but an elongated, pipe-shaped body with a cup-like termination, with a long duct passing through the center of the longitudinal, sac-like 'stem' of the gland. The termination of the duct is swollen and bulb-like, expanding in the bottom of the })enial gland cup. The penial gland duct is external as in Carinifex, but it is somewhat longer and of greater di- ameter. The jaw' is like that of Helisoma and is not fragmented like that of Carinifex. The genus stands out as one of the most distinct among American planorbids. In 1866, Dall instituted a subfamily Pompholiginae for Fomphoh/x effusa, basing the separation on the supposition that there were two pairs of eyes, one at the inner base of the tentacles and one at the end of the tentacles. The fact of this peculiar condition was positively stated by Mr. William ]\I. Gabb, who made drawings of the animal. Dr. J. E. Gray ( 1868, p. 387) questioned this statement. In 1870, Dall obtained specimens of a Fompholyx iFarapholyx) different specifically from the known species, which he called solida. An examination of the tentacles of this species at once cleared up the anomaly of the four eyes, the supposed eyes on the end of the tentacles being simply an aggregation of pigment. Only one pair of eyes is present, at the inner base of the tentacles, as is the case in other species of Planorbidae. Dall still retained the subfamily Pompholiginae (1870, p. 352) although the chief reason for its adoption, the four eyes, had been found to be invalid. The subfamilv has been used bv most writers on fresh-water Mol- lusca, including Fischer (1883, p. 507), Trvon (1884, p. 105), Walker (1918, p. 14), Germain (1922, p. 185), Henderson (1929, p. 143), and Chamberlin and Jones (1929, p. 155). Hannibal (1912, p. 161) elevated it to family status as Pomplioligidae. Dall has also used the name Pompho- liginae for a section of the marine genus Divaricella (Proc. U. S. Nat. INIus., XXIII, p. 814, 1901). The study of the animals of Carinifex and Farapholyx shows that they have no general anatomical characteristics not shared by Helisoma and the subfamilv Pompholiginae must therefore be abandoned. This course was indicated by Pilsbry in 1934 (p. 46). In 1936 (Nautilus, L, p. 30), the writer indicated the general anatomical features of Farapholyx, showing its general relationship to Helisoma and Carinifex and stating that the old subfamily Pompholiginae was without anatomical distinction. Genus PO^^IPHOLOPSIS Call, 1888 Type b}' original designation Pompholopsis tvhitei Call 1888. Pompholopsis Call, Amer. Geol., I, No. 3, p. 147. Type Pompholopsis whitei Call. As genus 1935. Pompholopsis J. Hexdersox, Fossil Xon-Marine Moll. N. A., p. 255. Type Pompholopsis ichitei Call. As genus 166 The Molluscan Family Planorhidae Shell (plate 76, fig. 11). 'Dextral, globose, rather solid, deeply iimbili- cated; whorls three to three and one-half, convex, body-whorl very large; sjiire short, apex obtuse; aperture roundly ovate; peritreme continuous, forming a heavy callus on the parietal wall of the body-whorl. Grovrth lines inconspicuous, surface of the shell smooth; sutures rather irregularly impressed. Length 7.26 mm.; diameter 8.13 mm.' (Call, 1888, p. 147). Geological Horizon and Distribution. Post-pliocene (Pleistocene). Tassajara Lake beds, California. Species Considered as Valid. Ponipholopsis ivhitei Call is the only species assigned to this genus. Remarks. Pompholopsis differs from Parapholyx in being deeply um- bilicated and in having a high spire and smaller, rounder aperture. It is related to Parapholyx but appears sufficiently distinct to justify a genus. A scries of shells might add greatly to our knowledge of the relationship of this species. Genus PLANORBARIUS Froriep, 1806 Type by original designation Helix cornea Linn. 1806. Planorharius Froriep, in Dumeril, Analyt. ZooL, p. 165. Type Helix cornea Linn. As genus 1810. Planorbis Moxtfort, Conch. Syst., H, p. 270. Type Planorbis corncus (Linn.). Non Geoffroy or Miiller. As genus 1840. Planorbis Swainson, Treat. Malac, p. 337. Type Planorbis corncus (Linn.). As genus 1847. CoreUis (Adanson, 1757) Gr.\y, Proc. Zool. Soc. London, p. 180. Type Pla- norbis Cornells (Linn.). As genus 1850. Spirodiscus Stein, Schn. u. Muscheln Berlin, p. 73. Type (1st species) : Planor- bis corncus (Linn.) 1855. Coretus Moquin-T.andon, Hist. Moll. Terr. Fluv. France, II, pp. 424, 445. Type Planorbis corneus (Linn.) 1870. Planorbis Dall, Ann. N. Y. Lye. N. H., IX, p. 351. Type Planorbis corncus (Linn.). As genus 1883. Spirodiscus Fischer, Man. de Conch., p. 509. Tyjie Helix corncus Linn. As section of Planorbis 1884. Planorbis Tryon, S. and S. Conch., Ill, p. 106. Type Planorbis corncus (Linn.). As genus 1885. Coretus We.sterlund, Fauna Pal. Reg., V, p. 64. No type cited. As subgenus of Planorbis 1886. Coretus Clessin, Conch. Cab., XVII, p. 32. Type Planorbis corneus (Linn.). As subgenus 1902. Spirodiscus Westerlund, Rad. Jugoslav. Akad., 151, p. 120. Type Helix cornea Linn. As subgenus 1905. Planorbis Dall, Alaska Moll., p. 81. Type Planorbis corneus (Linn.). As genus 1917. Planorbis Soos, Ann. Musei Nat. Hungarici, XV, pp. 37, 140. Type Planorbis corneus (Linn.) 1918. Planorbis Walker, Miscel. Pub. Mus. Zool., Univ. Mich., No. 6, p. 94. Type Planorbis corneus (Linn.). As subgenus of Planorbis 1921. Planorbis Germain, Rec. Ind. Mus., XXI, pp. 6, 9. Type Planorbis corneus (Linn.). As subgenus of Planorbis 1923. Coretus (Gray 1847) Wenz, Fossil. Cat., Pars 22, p. 1421. Genotype Coretus corneus (Linn.). As genus 1924. Planorbarius Kennard and Woodw.\rd, Proc. Mai. Soc. London, XVI, p. 10. Type Helix cornea Linn. Subfamilies, Genera, and Subgenera — Recent and Fossil 167 1926. Planorbiirius Kennard and Woodward, Syn. Brit. Non-Marine Moll., p. 67. Type Helix cornea Linn. As subgenus 1926. Planorbis Lindholm, Archiv. fiir Mollusk., Heft 6, year 58, p. 252. Ideogenotype Helix cornea Linn. As genus, type by Montfort 1927. Planorbis Pilsbry and Bequaert, Bull. Amer. Mus. N. H., LIII, pp. 115, 116. Type Planorbis corneus (Linn.). As genus 1929. Coretus (Gray 1847) H.^As, Trab. Museo Cien. Nat. Barcelona, XIII, p. 378. Type evidently Helix cornea Linn. As genus 1931. Planorbis F. C. Baker, Proc. Zool. Soc, London, p. 583. Genotype Helix cornea Linn. As genus 1931. Coretus (Andanson, 1757) Germain, Moll. Terr. Fluv. France, II, p. 517. No type cited but Planorbis corneus (Linn.) described. As subgenus of Planorbis 1931. Planorbis Thiele, Handbuch, Tcil 2, p. 479. Type Planorbis corneus (Linn.). Subgenus of Planorbis Miiller, 1774 Shell (plate'80, figs. 22-24). Large, sinistral, discoidal, rather solid, of few gradually enlarging whorls, equally visible above and below; aper- ture slightly enlarged, in the same plane as the whorls; lips sharp, not thickened. Animal. With short, wide foot, rounded before, tapering behind, the vela area large; tentacles long, wide at the base, and tapering to a point, eyes sessile at their inner bases. Color of living animal lead, sometimes nearly black tinged with brown; tentacles bluish black. Sometimes the whole body is reddish. The young snail of two whorls, recently hatched from the egg capsule, is very translucent, the organs plainly visible through the hyaline shell. The body shows pinkish through the shell, head and foot with border of white on edge. The radula sac may be seen working backward and forward, when feeding, as in the adult animal. The heart may be observed beating rapidly. The young snails are distinctly physoid in form and glide about like Physa. Specimens of the young with bifid tentacles are not uncommon. ANATOMICAL CHARACTERISTICS PLATE 20 {Planorbarius corneus (Linn.) ) GENITALIA. Male Organs (fig. 13). The seminal vesicle (SV) is about 4 mm. long and 1 nun. wide, narrowing at the anterior end to the diameter of the ovisperm duct. This organ is a rounded mass of small vesicles. A number of small vesicles continue down one side of the ovisperm duct. The sperm duct (SPD) is about 10 nnn. long. Where it leaves the ovisperm duct it is of small diameter, but it gradually enlarges to twice this diameter near the prostate where it abrui^tly expands to several times the first diameter, and then suddenly diminishes again to almost its original diameter. The prostate (PRS) is elongated and somewhat fan-shaped, 4.5 mm. long. The duct of the prostate is a continuation of the vas deferens and is about 1 mm. long. It lies over the sperm duct with which it is connected, the prostate diverticula radiating from this duct. The vas deferens (VD) is a narrow tube about 12 mm. long. The prostate in section A* 180 The Molluscan Family Planorbidae the preputium. A small supporting muscle may be present on the preputium below the retractor muscle. Internally, the penial complex is like that of exacuous (fig. 3). There is a large penial gland (GL) which may be folded back as shown in fig. 10. In section (fig. 11), it is like that of exacuous. There is an open, canal- like duct (see fig. 9). The verge (V) is short and wide, with a central opening of the sperm canal bordered by a distinct penial papilla (fig. 12). In the female system (fig. 1), there is a short spermatheca (S) with a wide duct twice as long as the spermatheca (SD). The vagina (V) is wide but shorter than in exacuous. The uterus (U) is wide and short and there is a swollen nidamental gland (NG). The oviduct (OD) is longer than in exacuous. The relationship of the oviduct, sperm duct and ovisperm duct is shown in fig. 7. The albumen gland is somewhat quadrangular in form and is composed of large vesicles (fig. 5). Of the hermaphrodite organs, the ovotestis is composed of paired diverticula. In the specimens examined, many of the diverticula were gravid (plate 43, fig. 1, (3T; fig. 8). The ovisperm duct differs from that of exacuous by having a number of small swellings on one side of the duct for half the length of the portion between the seminal vesicle and the oviduct. A portion of the ovisperm duct between the seminal vesicle and the ovotestis is without gland-like swellings. The penial complex of Menetus e.vacuou-s is figured by Baker ( 1928, p. 357, fig. 154). The retractor muscle is shown with an attachment to both the preputium and the vergic sac. This feature was not observed in any specimens more recently examined and this figure must be considered abnormal. All material studied, of exacuous and umbilicatellus, had a single retractor without two branches for the vergic sac and the preputium. The same criticism extends to fig. 157 on p. 362 of the work mentioned. Respiratory and Renal Systems. The pseudobranch appears somewhat variable in form, the variation being largely due to the amount of expan- sion of the organ. In specimens of e.vacuous from Winnebago Lake, Wis- consin (plate 41, fig. 8), it is large and leaf-like. In an example from Wainwright Park, Alberta (plate 42, fig. 1), it is fully expanded, wide and rounded below, with the anal opening conspicuously placed on one side within the area of the i:)seudobranch. It is somewhat folded in the middle. In a specimen of variety megas from Paul Lake, British Columbia (plate 42, fig. 2), the pseudobranch is rounded, and there is a smooth ridge extend- ing over a part of the rectum and forming a thickened border to the pseudo- branch. In umbilicatellus (plate 42, fig. 6), the pseudobranch is rounded in one specimen and folded in another (plate 43, fig. 2). In these examples, the anal region is outside of the area of the pseudobranch. There is no decided ridge on any specimen examined and the ridge on the rectum is not like that in Helisomatinae. The kidney (plate 46, fig. 3) of exacuous is 3.5 mm. long and about 0.5 mm. wide, rather long and narrow. The ureter is a long tube and turns at right angles to the long diameter of the kidney. It borders the thickened mantle margin on the inside. The pericardium is less than 1 mm. long. A cross section of the kidney near the middle (plate 46, fig. 4) shows an ovate lumen with a small vein on each side. There is no superposed ridge. The kidney of umbilicatellus is of the same shape and general nature as Subfamilies, Genera, and Subgenera — Recent and Fossil 181 that of exacuous, but the ureter bends backward at a sharper angle and is directed upward into the mantle cavity. Digestive System. The stomach is elongated with the gizzard longer than wide and with a rounded pyloris (plate 48, figs. 4, 5). There is a long blind sac or caecum (BS). The intestine (IN) makes a tight loop around the stomach, extends backward to the liver and then makes another loop and runs forward to the rectum. The buccal sac is elongated, with a rounded radular sac. The salivary glands are narrow, looped, and as long as the buccal sac. The superior jaw is arched, wide, and low, with the face vertically striated, as in other members of the group (plate 50, fig. 8, exacuous). In umbilicatellus (plate 50, fig. 15), there is a sharp median projection on the lower edge of the superior jaw. In exacuous, there is only a rounded bulge at this point. The side jaws are as in other species of the subfamily. The radula of exacuous has a squarish center tooth with expanded lower margins, the two wide, spade-shaped cusps not reaching the lower border of the base of attachment. The lateral teeth (1-6) are squarish, tricuspid, the mesocone longer and larger than the entocone and ectocone. All cusps are sharply pointed. The sixth lateral has a small cusp above the ectocone. Intermediate teeth begin on the seventh tooth, the entocone splitting into two long, sharp cusps and one or two small cusps appearing on the outer margin of the tooth above the ectocone (9-10). ^Marginal teeth (11-15) long and narrow, the entocone splitting into three to four small cusps and the outer margin of the teeth having two to three small cusps above the ectocone. The outer marginals are almost vestigial. The radula of umbili- catellus (fig. 2) is similar in form to that of exacuous. The radula data for Promenetus are as follows, two to four specimens of each having been examined: Locality Rows Collector Winnebago Lake, Wisconsin 110-112 F. C. Baker Wainwright Park, Alberta 115 Dr. Swales Wainwright Park, Alberta 138-140 Dr. Swales Vermilion Lake, Minnesota 140 F. C. Baker The material examined for the anatomical data described and figured in the preceding pages is listed below. Figures in parenthesis indicate number of specimens studied. cracuou-^: Winnebago Lake, Wisconsin, collected by F. C. Baker (4) ; Lake Nipissing, Ontario, received from the Canadian National Museum (5) ; Mott Lake, Wainwright Park, Alberta, collected by Dr. Swales (4) ; exacuous megas: Paul Lake, British Columbia, collected by Prof. D. S. Raw- son (2). umbilicateUus: Mott Lake. Wainwright Park, Alberta, collected by Dr. Swales (8) ; North Star Lake, Minnesota, collected by F. C. Baker (1); Vermilion Lake, Minne- sota, collected by F. C. Baker (2) . Specimens of exacuous from Wainwright Park, Alberta, were heavily infested with cercariae, more abundant in the ovotestis and liver. In several specimens both of these organs were almost obliterated. Geographical Distribution. The genus Promenetus has a wide distri- bution. It has been recorded from ]Maine west to Washington and Oregon and from Hudson Bay and Alaska south to New JMexico and Alabama. A single species {i7nus) is known from Bermuda. Species Form ula exacuous 17-1-17 exacuous 16-1-16 umhilicatellus 17-1-17 umbilicatellus 18-1-18 182 The Molluscan Family Planorhidae Species Considered as Valid. Five species, in one of which two races are recognized, are attributable to Promenetus. Promenetus exacuous exacuous (Say) Promenetus rubeUus (Sterki) Promenetus exacuous Jtiegas (Dall) Promenetus hudsonicus (Pilsbry) Promenetus umbilicatellus (Cockerell) Promenetus imus (Vanatta) Geological Distribution. Pliocene to Recent fauna. Remarks. Promenetus, first described as a group of the genus Menetus, differs so radically from Menetus in the form of the penial gland that it is deemed necessary to raise the group to generic rank. Its gland resembles Planorbula in the lack of a distinct duct and in the opening of the gland which is lengthwise instead of at the end of a cylindrical sac-like gland, as in typical Menetus and its subgenus Micromenetus. The form of the penial complex is also more like that of Planorbula than like this organ in Menetus. In other respects, the genus Promenetus conforms to the gen- eral characteristics of the subfamily. The discovery that the species long known as Gyraulus umbilicatellus is a Menetus closely related to exaciious (Baker, 1935, p. 46) was a surprise and shows that the group Promenetus includes species with both rounded and sharply carinated whorls. The vas deferens in typical Menetus enlarges as it enters the vergic sac to fprm an einphallus. In Promenetus and Planorbula, there is no such enlargement. Genus MENETUS H. and A. Adams, 1855 Type designated by D.\ll in 1870, Planorbis opercularis Gould 1855. Menetus H. and A. Adams, Genera of Rec. Moll., II, p. 262. Includes several unrelated species among which is Planorbis opercularis Gould. (Non Menetus of Chenu, 1869, P. Fischer, 1883, Tryon, 1884, C. A. Westerlund, 1885, or von Martens, 1899) 1865. Menetus W. G. Bixney, L. and FW. Sh. N. A., II, p. 125. No type cited but includes Planorbis opercularis and P. exacuous {== exacutus) . As subgenus of Planorbis 1870. Menetus Tryon, Con. Haid. Mon., pp. 188, 206. Xo type cited but inckides both Planorbis opercularis and P. exacutus. As subgenus 1870. Me7ietus D.\ll, Ann. N. Y. Lye. N. H., IX, p. 351. Type designation, Planorbis opercularis Gould. As subgenus 1886. Menetus Clessix, Syst. Conch. Cab., XVII, p. 33. Type Planorbis opercularis Gould. As genus 1905. Menetus D.^ll. Alaska Moll., pp. 82. 86. Type Planorbis opercularis Gould. Section of subgenus Hippeutis Agassiz 1918. Menetus Walker, Miscel. Pub. Mus. ZooL, Univ. Mich., Xo. 6, pp. 12, 94. Type Planorbis opercularis Gould. Section of subgenus Hippeutis Agassiz 1923. Menetus Wenz, Fossil. Cat.. Pars 22, p. 1650. Genotype Hippeutis (Menetus) opercularis (Gould). Few of the .species listed are true members of the genus Menetus, which is not found in Europe. They might belong in the genus Anisus. Subgenus of genus Hippeutis 1923. Menetus Germ.mx, Rec. Ind. Mus., XXI, pp. 8, 156. Tvpe Planorbis opercularis Gould. As subgenus of Planorbis 1926. Menetus F. C. Baker, Trans. Wis. Acad. Sci., Arts and Lett., XXII, p. 203. T3'pe Planorbis opercularis Gould. Anatomy. As genus 1928. Menetus F. C. Baker, Fresh-water Moll. Wis., I, p. 360. Type Planorbis oper- cularis Gould. Anatomy. As genus 1929. Menetus J. Henderson, Univ. Col. Studies, XVH, No. 2, pp. 140-141. As sub- genus of Planorbis Subfamilies, Genera, and Subgenera — Recent and Fossil 183 1931. Mcnclus Thiele, Handbuch, p. 481. Type Planorbis opercularis Gould. As sec- tion under Hippeutis, subgenus of Anisus 1934. Menctus Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 63. Type Planorbis oper- cularis Gould. Anatomy. As genus 1935. Menetus F. C. B.aker, Nautilus, XLIX, p. 47. Type Planorbis opercularis Gould. Anatomy. As genus Subgenus MENETUS SS. T^■])o Phowrbis opercularis Gould Shell (plate 79, figs. 22-24). Small, ultradextral, of few rapidly enlarg- ing whorls, the body whorl of large diameter compared wdth the inner whorls; right side flat, left side with the spire whorls deeply immersed; periphery or shoulder of body whorl more or less carinated ; aperture wide, more or less expanded; outer lip usually thin. Animal. The foot is comparatively short, the tentacles long and filiform. Color generally blackish. In general features the animal is like that of Planorhula. ANATOMICAL CHARACTERISTICS PLATES 38 AND 39 GENITALIA. Male Organs. [Menetus opercularis, type of the genus, plate 38, fig. 1). Seminal vesicle (SV) about 0.5 mm. long, twice the di- ameter of the ovisperm duct and about the same length. The vesicle proper has a few wide lobes, but the lower part (the ovisperm duct) is lined with small vesicles on the side. Sperm duct (SPD) about 1 mm. long, rather thick. Prostate (PRS) about 0.5 mm. long with about a dozen main diverticula. In section (fig. 2), the prostate shows several small diverticula projecting from a single, vertical diverticulum, there being usually five branches, one or more of which may be divided two or three times at the end (as in figs. 2, 3), or all may be single, long and club-shaped, as in cooperi (fig. 14). The vas deferens is 3 mm. long, about half the diameter of the sperm duct, and slightly enlarged as it enters the vergic sac. The penial complex (fig. 10) is elongated and sac-like, about 1.5 mm. long, of which the preputium, narrowed at the male genital opening, occupies 1 mm. or two-thirds of its length. There is a slight constriction between the preputium and the vergic sac (VS). There is one narrow re- tractor muscle (RjNI) attached to the base of the vergic sac. There are four sets of supporting muscles (SM) attached to the preputium. Most of these are branched several times. Internally (fig. 8), the preputium has two pilasters (PL). At the upper part of the preputium, there is a short penial gland which is doubled over in the normal position (GL). When expanded (fig. 6), this gland is trumpet-shaped, the bell-like cup fiaring. The cup cavity is provided with vertical folds, as in other Planorbidae. There is a dependent ring or dia- phragm between the preputium and the vergic sac cavity (D in fig. 8). The verge (V) is elongated and tapering and normally as long as the vergic sac. Female Organs (fig. 1). The spermatheca (S) is ovate, about 0.3 mm. long and has a very narrow duct (SD) almost 1 mm. long, which enters the short and narrow vagina (VG). The uterus (U) is about 0.2 mm. wide and 1 mm. long. The oviduct (CD) is very short (about 0.4 nnn.) and enters the ovisperm duct without notable decrease in size. There is a large 184 The MoUuscan Family Planorhidae carrefoiir (CF). The albumen gland (fig. 7) is about 1 mm. long and about half as wide as long. The vesicles are relatively large. The position of the albumen gland in relation to the other organs is shown in fig. 9. Hermaphrodite Organs. The ovotestis (OT) is composed of rather long, club-shaped diverticula. In section (fig. 5), they are seen to be in pairs, unbranched. The ovisperm duct is not free at any portion of its length, as is the case in cooperi and c. callioglyptus and other members of the Planorbulinae, but is lined with small, rounded vesicles (SO, fig. 1). A related, but distinct variety, c. callioglyptus, shows some noteworthy differences (plate 39, fig. 1). The seminal vesicle is twice the diameter of the ovisperm duct but the vesicles are longer and digitiform (SV). This is better shown in a California specimen (fig. 6), where the glands are in groups and branched. Rounded swellings or vesicles extend down the ovi- sperm duct some distance, but do not cover the entire length as in opcrcu- laris. The prostate (PRS) has 15-17 diverticula (see also fig. 13 in plate 38, a British Columbia specimen) . In section, the prostate is similar to that of opercularis (fig. 3, plate 38) or it may be unbranched, as in fig. 14, plate 38 (British Columbia specimen). The penial complex (plate 38, fig. 11, California specimen) is rather broader than that of opercularis, but the relative length of prcputium and vergic sac is the same. In specimens from British Columbia (plate 38, fig. 12; plate 39, fig. 9), there is a decided enlargement at the sunnnit of the vergic sac forming an epiphallus (EPI) as in some land snails. This was only slightly developed in opercularis (plate 38, fig. 10). There are five sets of supporting muscles in a California specimen (plate 38, fig. 11) but a lesser number in a specimen from British Columbia (plate 39, fig. 9). There is but one retractor muscle (RAI). A jicnial complex from a specimen collected in British Columbia, ba(ilv infested with flukes, is shown in fig. 10, plate 39. Internally (plate 39, fig. 7, Menetus cooperi), the preputium has two large vertical pilasters (PL). There is a large, sac-like penial gland (GL) with a short, narrow, tube-like internal duct (DC) which enters a canal in the muscular ring or diaphragm (D). In section (fig. 8), the gland shows a shallow cup (OC) at the outer end, lined with many vertical folds. A long duct runs through the fleshy part of the gland and connects with the short duct which emerges from the base of the gland. The penial gland of a Californian specimen of cooperi callioglyptus is shown in fig. 5. In this specimen, the gland was bent upward and somewhat contracted. The verge (plate 39, fig. 7, V) of cooperi is wide with thick walls. In section, it shows a large cavity connecting with the enlarged vas deferens (epiphallus) which narrows notably at the entrance of the vas deferens (fig. 7, EPI, VD). The end of the verge is shown in fig. 15, plate 38, indicating the centrally located exit of the sperm canal. The natural position of the penial complex beneath the female organs (vagina and uterus) is shown in fig. 3, plate 39. In the female organs, the spermatheca (plate 39, fig. 1, S) is much elongated and sac-like and the duct is narrow, widening somewhat as it enters the vagina. The duct is about as long as the spermatheca. The other organs are similar to those of opercularis. Pilsbry (1934, p. 64, fig. 7a) figures the penial complex of Menetus cooperi callioglyptus (Vanatta) and this is similar to the figures in the Suhjamilies, Genera, and Subgenera — Recent and Fossil 185 present work. The verge is figured rather longer than was observed in specimens personally examined, but this organ is variable in form under different conditions. The }x^culiar epiphallic enlargement of the vas deferens is shown in Pilsbry's figure. The statement that the prostate alveoli (diverticula) are in a single series needs emendation, for while they ai^pear to be in a single series when viewed in position over the nidamental gland, in a cross section they are seen to be composed of several brandies, as figured on plate 38 (figs. 2, 3). The diverticula in the natural position are hidden beneath the large diverticulum (as in fig. 1 in both plates 38 and 39) and the series appears simple. There is considerable difference between the genitalia of Menetus operculaj'is and M. coopcri, particularly in the penial complex, in which the form of the penial gland and the size of the eiiiphallus differ. This differ- ence indicates that the two forms are distinct species. There is some slight variation between specimens from British Columbia and California, but in general the anatomical features are similar. Respiratory and Renal Systems. The pseudobranch of opercularis is wide, somewhat folded or lobed and the rectum extends through the middle, the anus opening at the lower edge (plate 38, fig. 4, P, A, R). There is a large pneumostome. In cooperi callioglyptus (plate 39, figs. 2, 4), the pseudobranch is rounded, somewhat lobed, and with a high ridge extend- ing o^'er the length of the rectum (R) and running down the midde of the pseudobranch as a low ridge. The anal opening is placed at the left side of the pseudobranch. This ridge is also found in opercularis, but is not indi- cated in the figure. The two forms of pseudobranch shown in figs. 2 and 4 on plate 39 indicate the amount of variation that may take place in two individuals of the same species. The kidney (plate 46, fig. 7) of Menetus cooperi callioglyptus is short and very wide (about 2 mm. long and 1 mm. wide). The ureter is a rather long, narrow tube reflexed abruptly and directed upward into the mantle cavity. The pericardium is about 1 mm. long. The lower part of the kidney is very close to the mantle margin, the ureter being in contact with it. A cross section of the kidney near the middle (fig. 8) shows the lumen to be large, ovate, somewhat wider than high, the vein leading to the pericardium much greater in diameter than the renal vein. There is no superposed ridge. Digestive System. The stomach region is elongated, the oesophagus enlarged to form a crop, the gizzard rounded, and the pyloris rounded and diminishing to the intestine which forms a complete loop around the stomach, extends backward in the body, makes another loop around the liver, and runs forward to the rectum, ending over the pseudobranch. There is a long and narrow blind sac or caecum. The stomach region is like that of Promenetus exacuous which is figured on plate 48, figs. 4, 5. The buccal sac is pyriform, with a large, rounded extension of the radula sac at the lower, posterior part. The salivary glands are about twice as long as the buccal sac and are much enlarged at the posterior end where they are attached, the whole apparatus forming a loop. The oesojihagus is enlarged to twice its diameter posterior to the buccal sac. The superior jaw of cooperi callioglyptus (plate 50, fig. 7) is arched, the ends attenuated. There is a central rounded bulge on the lower margin. The jaw is heavily, vertically striated. The side jaws are normal except 186 The Molluscan Family Planorhidae that at the i^oint of attachment to the superior jaw they are bent back- ward more than usual. The jaw of Menetus opercularis is similar. The radula of Menetus cooperi callioglyptus (plate 67, fig. 3, from British Columbia) has a large center tooth, higher than wide, the two wide, spade-shaped cusps not reaching the lower border of the base of attach- ment. The lateral teeth (1-8) are sciuarish and tricuspid, the cusps long and spade-shaped, the mesocone the longest. The intermediate teeth (9-10) are narrower than the laterals and have one or two additional cusps above the ectocone. The entocone, mesocone, and ectocone become more nearly equal in length. The marginal teeth (11-15) are very narrow, elongated, the ento- cone is split into from two to four small cusps and the ectocone splits into three to four small cusps. The outer marginal teeth are very narrow and appear to be serrated with small cusps. The mesocone persists throughout the entire series of teeth and may always be identified. Data for Radula Name Formula Locality Rows Collector cooperi callioglyptus 20-1-20 Quatsino, British Columbia 144-145 Mr. Arthur Peake cooperi 20-1-20 Orcas Ishmd, Washington 155-161 Dr. T. D. Foster The material for the study of Menetus was received from the following sources: opercularis from Mountain Lake, near San Francisco, California, collected by Mr. H. Walton Clark, two specimens examined; cooperi callioglyptus, Quatsino Sound, Vancouver Island, British Columbia, col- lected by Mr. Arthur Peake, eleven specimens examined; mill pond at Crescent City, California, received from Dr. G. D. Hanna, four specimens studied; cooperi, from Orcas Island. Puget Sound, small mountain lake on Mt. Constitution, Washington, collected by Dr. T. D. Foster, fifteen specimens examined. Specimens of cooperi callioglyptus from Quatsino Sound, Vancouver Island, were largely infested with cercariae of trematode worms, as many as 200 larvae occurring in one specimen. All organs were affected but the ovotestis and albumen gland were more often attacked. The parasites were most numerous over the stomach region. Specimens of cooperi from Orcas Island, Puget Sound, had parasites in liver, ovotestis, albumen gland, and over the stomach. In some specimens from both Washington and British Columbia all of the organs were obscured by a thick coating of mucus. Geographical Distribution. Tyjiical Menetus is distributed over the Pacific coast region from Vancouver Island south to nortliern California. The group does not extend far inland to the east. It is distinctively a genus of the coast region. Only a few species are known. Opercularis appears to be confined to California, but cooperi (=^ planulatus) is found from northern California northward to Vancouver Island, and within this area is cjuite variable. There are a number of local forms of limited distribution. Species Considered as Valid. The following species and races are at present known for the typical subgenus of Menetus. Menetus opercularis (Gould) Menetus cooperi callioglyptus (Vanatta) Menetus cooperi F. C. Baker, new name Menetus cooperi multilineatus (Vanatta) for planulatus Cooper, 1859, not Menetus centervillensis (Tryon) planulatus Deshayes, 1824, a fossil species. Subfamilies, Genera, and Subgenera — Recent and Fossil 187 Geological Distribution. Pliocene to Recent fauna. Little is definitely known concerning the geological ancestry of this genus. Remarks. Typical Menetus is a very distinct genus characterized by noteworthy anatomical features, chief among which are the sac-like penial gland with its short, narrow, internal duct and the epiphallus-like enlarge- ment of the vas deferens as it enters the vergic sac. The prostate resembles that of Planorbula which has the same structural arrangement of divertic- ula. The ovotestis is also like that of Planorbula. The penial gland, how- ever, is quite unlike either that of Planorbida or Promenetus. The duct is also different . The radula and jaw are like these organs in Promenetus and Planorbula. Menetus has been subordinated to several groups as a section or sub- genus. Thiele phices it under Anisus ( 1931, p. 481 ) , Dall as a section under subgenus Hippentis (1905, p. 82), Germain as a subgenus of Planorbis (1923, p. 156). Von Martens (1899, p. 390) includes in it species now referred to Tropicorbis. The Adams brothers indicated no type, though one was definitelv proposed bv Dall in 1870 (p. 351). F. C. Baker (1928, p. 360) and Pilsbry (1934, p. 64) have shown definitely that the group should rank as a genus. The anatomical figures herein published support this conclusion. Subgenus MICROMENETUS F. C. Baker, New Subgenus Genotype Planorbis dilatatus Gould Shell ("plate 79, figs. 13-15) . Very small, ultradextral, of few rapidly enlarg- ing whorls ; right side flat or convex, left side with inner whorls submerged by the body whorl; body whorl with a more or less well-developed carina, usually placed just below the top of the right side; aperture large, some- what dilated; lips thin. Animal. Foot short, wide, oval on base, bluntly rounded before and behind; tentacles long and filiform, enlarged somewhat at base, attaclied far back on the head; eyes on small swellings at inner base of tentacles; color mottled brown and cream, whole back dark, two black lines extending down middle of head; bottom and sides of foot yellowish; tentacles trans- parent. Shape of foot varies during locomotion. The shell is carried at an angle of thirty to forty-five degrees or it may lie flat on the body of the animal. It is seldom carried erect as in Helisoma (plate 70, fig. 9). ANATOMICAL CHARACTERISTICS PLATE 40 GENITALIA. Male Organs (fig. 12). Seminal vesicle (SV) of M. dilata- tu.s made up of a small number of relatively large vesicles placed on each side of the ovisperm duct. Anterior to the seminal vesicle, the ovisperm duct is bordered by a number of widely spaced vesicles for a distance three times the length of the seminal vesicle. Sperm duct (SPD) of small diameter, not much greater than that of the ovisperm duct. The combined free por- tion and that part beneath the prostate measure about 1 mm. in length, the sperm duct being a trifle longer than the prostate portion. Prostate (PRS) with relatively few diverticula, eight or nine. In cross section, the prostate shows the same multiplication of smaller diverticula on the under side as is present in Menetus opercidaris. In an immature specimen of 188 The Molluscan Family Planorhidae cooperi, the prostate had but five rows of diverticula. The vas deferens is a narrow tube ahiiost as long as the sperm duct. It is slightly enlarged near the vergic sac. In Menetus sampsoni, the seminal vesicle (fig. 1 ) differs from that organ in cooperi in being composed of four rounded swellings. Only a few rather large vesicles occur on the ovisperm duct. The penial complex (fig. 12) is about 0.5 mm. long, the preputium (PR) is sac-like or elongate-pyriform and is about twice as long as the ovate vergic sac (VS). In sampsoni (fig. ID, the vergic sac is longer and wider. There is one retractor muscle (RM) which is usually attached to the con- striction between the preputium and the vergic sac (fig. 11). There are several small supporting muscles on both sides of the preputium. The penial complex was observed in several different forms in the material examined. In one (fig. 3), the vergic sac was placed on the side of the preputium, the gland being pushed upward, as occurs so frequently in the genus Helisoma. In another specimen (fig. 4) , the preputium was much swollen and the retractor muscle was attached to the preputium some dis- tance below the vergic sac. Internally (fig. 5), there is a sac-like penial gland with a rather long duct. This is shown to better advantage in Menetus sampsoni (fig. 10), where the gland (GL) is much elongated and gradually diminishes in diameter to the round duct, which follows the wall of the preputium (DC) to the muscular ring or diaphragm separating the preputial sac from the vergic cavity. The cup containing the vertical folds is small and is placed at the end of the penial gland. There is a central duct running through the gland as in Menetus cooperi callioghjptus. In a Texas specimen (fig. 2) , the gland was somewhat different, resembling a pipe or trumpet. This might have been abnormal. The verge (fig. 10, V) is elongated, narrowing to a point at the lower end. The sperm canal has a central outlet. See also fig. 5. Female Organs. The spermatheca (fig. 12, S) is short and sac-like and is connected with the very wide vagina (VG) by a wide duct twice as long and half as wide as the spermatheca. The uterus (U) is wide, increas- ing to about twice the diameter of the vagina in the region of the prostate, where the still wider nidamental gland (NG) appears. The oviduct (OD) is short and gradually narrows to meet the sperm duct. There is a carre- four which lies between the oviduct and the albumen gland (not shown in the figure). The albumen gland (AL) is very large and wide (almost half as wide as long) and is composed of large vesicles. The intestine makes a loop beneath the albumen gland (IN). Hermaphrodite Organs. The ovotestis (OT) is composed of relatively few large, somewhat club-shaped diverticula arranged in pairs. A single diverticulum filled with developing ova is shown in fig. 6. The diverticula vary in form, being more swollen when filled with ova ready for discharge. Respiratory and Renal Systems, The pseudobranch of dilatatus (plate 40, figs. 7, 9) is about twice as long as wide and extends below the margin of the foot in preserved specimens. It is somewhat folded on the side and in a Texas specimen {sampsoni, fig. 8) formed a hollow cylinder. There is a fluted crest on the rectum (R) which, however, does not appear on the pseudobranch in the specimens examined. The anal opening (A) is jilaced at the upper end of the pseudobranch. Subfamilies, Genera, and Subgenera — Recent and Fossil 189 The kidney (fig. 5) is rather short, about 1 mm. long and 0.3 mm. wide. The ureter is very long and is folded back tightly against the lower part of the kidney. A cross section near the middle of the kidney (fig. 6) shows an oblong or ovate lumen with a small vein at each end. There is no super- posed ridge. The kidney is wider than that of exacuous but narrower than that of cooperi or c. callioglyptus. The pericardium is very wide. Digestive System. The digestive system is similar to that of exacuous (see plate 48, figs. 4, 5). The radula sac is essentially the same as in Menetus. The superior jaw (plate 50, fig. 9) of dilatatus is wide and low with vertically striated face. The side jaws are as long as the width of the superior jaw. The jaws of sampsoni (fig. 6) are similar, but larger. There is a slight bulging in the center of the lower cutting edge of the superior jaw in both dilatatus and sampsoni. The radula (plate 67, fig. 4, dilatatus). Center tooth squarish, not as wide as in typical Menetus. Lateral teeth ( 1-7) squarish, tricuspid, the mesocone longest, all cusps sharp and spade-shaped. Intermediate teeth (8-10) becoming narrower and developing a split entocone and one or two small cusps above the ectocone. Marginal teeth (11-14) long and narrow, the entocone with three to four small subequal cusps, the ectocone with several small cusps on the outer edge of the teeth. The marginal teeth become much smaller toward the edge of the membrane. The radula of sampsoni is practically of the same type as that of dilatatus (fig. 5). Radula Data Name Formula Locality Rows Collector dilatatus 15-1-15 Unionville, Connecticut 125 F. C. Baker dilatatus 15-1-15 Hyannis, Alassachusetts 125 F. C. Baker sampsoni 15-1-15 IMerrimec R., Missouri 125 Leslie Hubricht sampsoni 15-1-15 Dallas, Texas 120 E. P. Cheatum The material examined for anatomical data has been as follows: dilatatus, near Unionville, Connecticut, twelve miles west of Hartford, col- lected by F. C. Baker (16) ; near Hyannis, Cape Cod, ]\Iassachusetts, collected by F. C. Baker (2) ; sampsoni, Merrimec River, near Stanton, Franklin County, ^Missouri, collected by Mr. Leslie Hubricht (14) ; small creek, six miles northeast of Dallas, Texas, collected by Dr. E. P. Cheatum (4) ; slough, near Trinity River, twelve miles southeast of Dallas, Texas, collected by Dr. Cheatum (2) ; small lake, near Hutchins, Dallas County, Texas, collected by Dr. Cheatum (2). The cercariae or rediae of trematode worms were found in some of both species of Micromenetus. Of dilatatus, near LTnionville, Connecticut, one specimen infested; sampsoni, Merrimec River, Missouri, nearly all speci- mens examined, many of the specimens being badly diseased. Geographical Distribution. The species belonging to the subgenus Micromenetus are distributed over the eastern part of North America from Massachusetts west to Iowa and Missouri, and from Maine and ^Michigan southward to Alabama, Florida, and Texas. It is a group found east of the Rocky Mountains. One species, Menetus uliginosus Vanatta. is found in Bermuda. 190 The MoUuscan Family Planorbidae Species Considered as Valid. There are several distinct species and races of the subgenus Micromenetus recognizable within the genus Menetus, as follows: Menetus (Micromenetus;) dilatatus Menetus (Micromenetus) alabamerisis dilatatus (Gould) aims Pilsbry Menetus (Micromenetus) dilatatus penn- Menetus (Micromenetus) brogniartianus sylvanicus Pilsbry (Lea) Menetus (Micromenetus) dilatatus Menetus (Micromenetus) sampsoni buchanensis (Lea) (Ancey) Menetus (Micromenetus) alabamensis Menetus (Micromenetus) uliginosus alabamensis Pilsbry Vanatta Geological Distribution. Not exactly known but certainly from the Pliocene to Recent fauna. Remarks. The group here separated as Micromenetus differs from typical Menetus in the size of the shell which is always much smaller, none exceeding 4 mm. in diameter. The form of the shell is lenticular and there is usually a peripheral carina more or less well develoiied. The penial gland has a duct which is almost three times as long as the gland and is attached to the inner wall of the preputium for the greater part of its length (plate 40, fig. 10). In typical Menetus, this duct is short and enters the diaphragm directly without being attached to the wall of the preputium (plate 39, fig. 7). Tlie pseudobranch in Micromenetus is also very long and narrow while in typical Menetus it is short and wide (compare jilate 38, fig. 14, with plate 40, fig. 9). These are small differences, perhaps, but they appear constant. Micromenetus differs from both Promenetus and Planorbula in the shape of the penial gland. As far as examined the radulae of the two groups differ in formulae, that of Menetus being 20-1-20 while in Micro- menetus it is 15-1-15. Genus PLANORBIFEX Pilsbry, 1934 Type by original designation Planorbis vanvlecki Arnold 1934. Planorbijex Pilsbry, Proc. Acad. Nat. Sci. Phil., 86, p. 568. Genotype Planorbis vanvlecki Arnold. As subgenus of Menetus 1935. Menetus (Planorbijex) vanvlecki Pilsbry, J. Henderson, Fossil Non-Marine Moll. N. A., p. 252. Shell (plate 81, fig. 6). Discoidal, dextral in appearance, the right side moderately convex, with the last whorl carinate, the periphery rounded; left side deeply umbilicate, the last whorl more or less flattened. Sculpture of fine, close, hair-like striae. Aperture strongly oblique, its outline excised bv the preceding whorl, the receding left margin thickened within (Pilsbry) . Geological Horizon and Distribution. Basal part of the Tulare forma- tion. Pliocene. North dome, Kettleman Hills, Kings County, California. Species Considered as Valid. The fossil species Planorbijex vanvlecki Arnold, as genotype, is the only species known for this genus. Remarks. 'Except for the narrow umbilicus, the absence of a peripheral keel, and the thickened peristome, this form resembles Platytaphius Pilsbry, a much larger planorb from Lake Titicaca, which has similar sculpture. Paraplanorbis Hanna resembles Planorbijex in being small and Subfamilies, Genera, and Subgenera — Recent and Fossil 191 narrowly iinibilicatc, but it has a spire of closely coiled whorls like Drepanotrema. The small size and umbilicate left side are like Menetus, which, as Arnold thought, is probably its nearest relative; but in carinate species of Menetus the keel is peripheral' (Pilsbry, 1934, p. 568). 'The shell of the type species, Planorbifex vanvlecki, varies in the amount of flattening of the base; sometimes it is scarcely noticeable. The species was referred by Dr. Cooper to Valvata virens, a very different shell. It has certain resemblances to such forms as Valvata bicarinata Lea, but the excised outline of the strongly oblique aperture, and the thickened peristome, exclude a reference to the Valvatidae, some of which have a similar sculpture' (Pilsbry, 1934, p. 569). As remarked under the genus Paraplanorbis, it appears better to regard Planorbifex as a separate genus related to Menetus rather than as a sub- genus of Menetus. The carina in the middle of the whorl of the right side is distinctive, and is different from any known species of Menetus or Pro- menetus, where the carina is peripheral or just below the margin of the left side. VIII. GROUPS OF UNCERTAIN AFFINITIES Subfamily CHOANOMPHALINAE Germain, 1923 Characters those of the genus Choanomphalus Gerstfeldt Genus CHOANOMPHALUS Gerstfeldt, 1859 Type by original designation, Choanomphalus maacki Gerstfeldt 1859. Choanomphalus Gerstfeldt, Ueber Land imd Siisswasser-mollusken Siberiens, p. 527. Type Choanomphalus maacki Gerstfeldt. As genus 1870. Choanomphalus Dall, Ann. N. Y. Lye. N. H., IX, pp. 353, 358. Type Choanom- phalus maacki Gerstfeldt. As genus 1875. Choanomphalus W. Dybowski, Die Gasteroi)oden Fauna Baikal-See. Mem. Acad. Sci., St. Petersburg, Ser 7, XX, p. 52. Type Choanomphalus maacki Gerst. As genus 1879. Choanomphalus Crosse and Fischer, Jour, de Conch., XXVII, p. 160. Type Choanomphalus maacki Gerst. As genus 1883. Choanomphalus Fischer, Man. de Conch., p. 508. Type Choanomphalus maacki Gerst. As genus 1884. Choanomphalus Tryon, S. and.S. Conch., IH, ji. 105. Type Choanomphahis maacki Gerst. As genus 1885. Choanomphalus Westerlund, Fauna der palaarct. Region Binnenconchylien, V, p. 63. Type Choanomphalus maacki Gerst. As genus 1886. Choanomphalus Clessin, Syst. Conch. Cab., XVII, p. 232. Type Choanompha- lus maacki Gerst. As genus 1909. Choanomphalus Lindholm, Mollusken, in Korotneff, Wissens. Ergebn. Zool. Exped. Baikal-See, IV, pp. 8, 93. Type Choanomphalus maacki Gerst. As genus 1923. Choanomphalus Germain, Rec. Ind. Mus., XXI, p. 190. Type Choanomphalus maacki Gerst. As genus 1925. Choanomphalus Dybowski and Grachmalichi, Kosmos, L, p. 877. As genus 1931. Choanomphalus Thiele, Handbuch, p. 482. Type Choanomphalus maacki Gerst. As genus Shell (plate 81, figs. 7, 8, 9) small, pseudodextral, turbinate, of few whorls rather rapidly increasing in diameter, the spire depressed but not flat, base widely umbilicated or with a small chink; aperture rounded. The shell resembles some species of Valvata in form. Animal. Similar to Plonorbis in tentacles, jaw, and radula. Respiratory and genital openings on the left side (see Dybowski and Grachmalichi, p. 870) . The eggs are laid in capsules with four to five eggs in each capsule. The jaws are three in number with a large, half-moon-shaped superior jaw and two small lateral jaws. The radula plate measures 1.6 mm. in length and 0.3 mm. in width, and carries 175 rows of teeth. The formula of Choanomphalus maacki is (4)- 9-5-16-1-16-5-9- (4) (69 teeth in row) or sixteen lateral teeth, five inter- mediate teeth, nine marginal teeth, and four outer marginal teeth without distinct form. In Choanomphalus valvatoides the formula is (3) -10-5-10-1- 10-5-10- (3) (57 teeth in row). In Choanomphalus bicarinatus the formula is 4-6-20-1-20-6-4 (61 teeth in row). Choanomphalus cryptomphalus has the formula 5-6-20-1-20-6-5 (63 teeth in row). The smallest formula is borne by Choanomphalus schrencki which is 4-7-1-7-4 (23 teeth in row), 192 Groups of Uncertain Affinities 193 the outer marginals indistinct and uncountable (op. cit., p. 871). No men- tion is made of the cusps of the teeth. There seems to be great uniformity in the total number of teeth but some variation in the number of lateral teeth. The published information concerning the anatomical details is wholly insufficient for purposes of classification. Geographical Distribution. Lake Baikal, Siberia. The different species occur at varying dei)ths, thus maacki occurs at great depths, principally between 150 and 350 meters. Valvatoides, on the other hand, occurs in comparatively shallow water, from two to ten meters. One species is found in the Angara River, near Lake Baikal iamauronicus). Another species is found in Japan ( japonicus) . Westerlund includes Europe, Thessalia, be- tween Greece an^l Turkey, in the distribution of the genus. This range needs confirmation. Remarks, The genus Choanoinphalus is a group of mollusks probably related to the Planorbidae but of uncertain status as to its proper position in the classification of the fresh-water pulmonates. Dall (1870) and Tryon (18841 placed the genus, in the subfamily Pompholiginae with Pompholyx {Paraphohjx) and Carrriifex. Crosse and Fischer in 1879 compared the genus with the American group Carinifex and suggested its group relation- ship with the fossil Valvata multiformis { = trochiiormis) . The resemblance to Carinifex in both Choanomphalus and the Steinheim fossil itrochi- formis) is superficial, Choanomphalus not having the same characteristics of anatomy found in Carinifex and Paraphohjx. Westerlund, in 1902 (p. 120), placed Choanomphalus in the subfamily Planorbinae. In 1909, W. A. Lindholm made a study of the Lake Baikal fauna and divided Choanomphalus into three subgenera, as noted below. 1. Choanomphahis Sensu Stricto. Type Choanomphalus maacki Gerstfeldt 2. Achoaiiomphalus Lindholm. Type Choanomphalus amauronius Bourguignat 3. Sulcifer Lindholm. Type Choanomphalus schrencki W. Dj-bowski The Japanese species is placed in a separate section by Lindholm, Choanomphalodes, 1927; type Choanomphalus japonicus Preston. Germain (1923) places the group in a subfamily Choanomphalinae. Dybowski and Grachmalicki ( 1925, pp. 819-881 ) , in an exhaustive mono- graph, review all of the species of Choano))iphalus, some twenty-five in number, of which fifteen are considered valid. The peculiar Planorbis para- doxus Sturany, from Lake Ochrida near the city of Ochrida, in European Turkey, is discussed, but its relationship to Choanomphalus is questioned. It has been thought to be related to Choanomphalus by Sturany and other European conchologists. It probably represents another peculiar form of Planorbidae and its anatomy should be examined. The suggestion in the foregoing reference (p. 835), that Segmentina may be related to Choanomphalus is obviously erroneous because that genus has been shown to be the type of a distinct subfamily not known to have any affinities with the Baikal Lake group. A form of Segmentina nitida is found in Lake Baikal and is given the name of angarensis by these two authors. On pages 877 to 880, Dybowski and Grachmalicki present a new ar- rangement of Choanomphalus which is made a separate family, Wladis- laviidae. Six genera and some twenty-three lesser groups are designated. 194 The Molluscan Family Planorbidae The subgeneric names proposed by Lindholm in 1909 are ignored. These six genera, as listed by Thiele (1931, p. 482) with the earlier names of Lindholm and the new names proposed by Tomlin for the preoccupied names, are tabulated below. 1. Choa7iomphaIus (SS). Type Choanomphahis maacki Gerst. 2. Valvatomphalus D. and G. {= Achomwmphalus Lindholm, 1909). Type C. amau- ronicus Bourg. 3. Cryptomphalus D. and G. (non Charpentier, 1837)= Omphalocrypta Tomlin, 1929. Tvpe C. cryptoinphahis W. Dybowski 4. Biangulatiis D. and G. Type Choanomphahis bicarinatus Dybowski 5. Anomphalus D. and G. (non Meek and Worthen, ISQ^)^ Anomphalodes Tomlin, 1929. Tvpe C . anomphalus W. Dvbowski 6. Platybasafis D. and G. {= Sulci) er Lindholm. 1909). Type C. schrc7icki W. Dy- bowski The value of these generic and group names is debatable. The plate of species in the Dybowski and Grachmalicki monograph docs not show variation enough to warrant any such minute division, and many of the figures suggest individual variation, such as is common among many of our North American species of Helisoma. Possibly the few groups and species enumerated by Lindholm can be recognized, judging from the figures in Fischer's paper (1879, plate 4, figs. 8-10) which are reproduced on my plate 81. Just why all of the Lake Baikal species of Choanomphahis should not be included in the one genus is not apparent from a study of the shells and what little is known about the animals. The name Wladislaviidae can not be used because Germain in 1923 (p. 190) proposed the subfamily name Choanomphalinae two years earlier. On this page Germain also questions the value of recognizing subgenera for the different species. Until the details of the genitalia arc known, particularly the form of the ovotestis, prostate, and the internal conditions of the penial complex, it will be impossible to determine the true position of this group in the classification of the fresh water pulmonates. For the present, the group designation of Germain as a subfamily of Planorbidae should be retained. It is possible, of course, that when the anatomy is known the group might be found to be of family rank, but in that case the name of Germain must be used because it was given at an earlier date than Wladislaviidae of Dybowski and Grachmalicki. Genus POECILOSPIRA :\Iorch, 1853 Tj'pe by original designation Valimta muUijormis Zeiten 1853. Poecilospira Morch, Cat. Conch. Yoldi. Type Valvota multiformis Zeiten {= Helicites trochiformis Stahl. 1824) 1879. Poecilospira Crosse and Fischer, Jour, de Conch.. XXVII, p. 160. Type Valvata muUijormis Zeiten. As genus 1884. Poecilospira Tryon. S. and S. Conch., Ill, p. 105. Type Planorhis muUijormis (Zeiten). As subgenus of Choanomphahis Shell (plate 81, fig. 1). Dextral, varying from fiat with depressed spire, discoidal, to trochiform with greatly elevated spire, the last whorl rounded and in the same plane as the body whorl or greatly deflected. Whorls carinated, the carina placed at the upper side of the whorl in planorboid forms and forming a peripheral ridge in the forms with elevated spire. Umbilicus large and conspicuous. Aperture round or lunate, entire and Groups of Uucertain Affinities 195 separated from the body whorl, a thick callus on the parietal wall and the outer lip thickened in many specimens. Horizon and Distribution. ^Miocene period. Steinheim near Heiden- heim, Wiirttenberg, Germany. Remarks. The planorbid fauna at Steinheim has become classical for studies of variation, not only as individuals in a fauna, but also in time between the earlier and later strata. Perhaps Hyatt's studies in 1880 (pp. 1-114, plates 1-9 » are the best known and show in large measure the great amount of variation which has taken place during the life of these mollusks while the Tertiary strata w^ere being formed in the old lake bed and on its shores. Hyatt refers all species to the genus Planorbis. In a later paper (1920, pp. 155-216, Taf. 10-12), Gottschick reviews what is known concerning the fossils of this locality. He postulated a cold- Avater fauna and a warm-water fauna, as we sometimes find in the Pleisto- cene faunas of the middle west. This paper is well illustrated and shows the great variation in the group of shells known as Planorbis ))iultiformis. Wenz (1923, p. 1601 1 includes all of the Steinheim fossils in the genus Gyrauhis. The work of Wenz also brings out clearly the fact that the fossils of this and nearby regions have been very much overnamed, for between 1824 and 1920 no less than forty-five names have been given to variations of this group. A careful study of the works of Hyatt, Gottschick, and others shows that, while many of the so-called species appear to be referable to the genus Gyrauhis, the forms grouped around multiformis (trochiformis) appear different from the Gyraulus-like shells, approaching Valvata in form, and apparently should be segregated in another group. Morch, in 1863, recognized this difference and gave the assemblage the name of Poecilospira. Later authors appear to have overlooked this name which does not appear in recent monographs or check lists. It is not mentioned by Wenz (1923) in the list of fossils related to trochiformis. To what group Poecilospira is related is not definitely clear. It is cer- tainly not near Gyraidus and apparently does not belong in the subfamily Planorbinae. Also, it is not related to Carinifex or to any of the fossil relatives of this group. There are some features in common between Poecilospira and Choanomphalus and its true position may be with the latter group, as suggested by Tryon in 1884. IX. FAMILY BULINIDAE This group has ahnost universally been considered a subfamily of Planor- bidae. It is so treated by Pilsbry (1927, p. 132). More recently several authors have considered the group as of family rank, distinct from the Planorbidae (Germain, 1931, p. 514; Larambergue, 1939). The shell is of Physoid shape but the radula is like that of Planorbis. Two characteristic features of the group separate it from any known division of the Planor- bidae, the fluted or lobular })seudobranch and the shape of the ]ienial com- plex in the genitalia. These are so different that they would appear to be characteristics of family rank. The family is mostly exotic, distributed as far as known in Australia, Oceania, New Guinea, Celebes, Japan, India, the Ethiopian and Malagasy regions, the ^Mediterranean subregion as far east as Mesopotamia, and the Antilles (vide Pilsbry, 1927, p. 132). Only one species occurs in the Antillcan region. The present work was prepared to include only the groups i)roperly belonging to the family Planorbidae, but as one species previously referred to the Planorbidae has recently been placed in Bulinidae, space is given to a discussion of this species and the data for its inclusion in a family to which it was not previously believed related. Genus INDOPLAXORBIS Aiinandale and Prashad. 1920 Type by original designation, Planorbis exustus Deshayes 1920. Iitdoplanorbis Ann.\nd.\le and Pr.\sh.\d, Jour. Med. Res., VIII, p. 112. Type Planorbis exustus Deshayes. As genus 1921. Indoplanorbis Pr.ash.\d, Rec. Ind. Mus., XXII, p. 471. Tvi)p Planorbis cxuslus Desh. As genus 1921. Indoplanorbis Axn.\ni).\le and Pk.\.shad, Roc. Ind. Mus., XXII, p. 578. Type Planorbis exustus Desh. As genus 1921. Planorbis (PUmorbis) exustus Germ.mx, Rec. Ind. Mus., XXI, pp. 26-41. Ex- haustive account of variation and .synonymy 1922. Indoplanorbis Anx.and.\le and Pr.\sh.ad, Rec. Ind. Mus., XXIV. p. 360. Type Planorbis exustus Desh. As genus 1923. Indoplanorbis Rao, Rec. Ind. Mus., XXV, pp. 199-219. Tyi)e Planorbis exustus Desh. Description of anatomj'. As genus 1926. Indoplanorbis Thible, Handbuch, p. 479. T^-pe Planorbis exustus Desh. As section of Planorbis 1933. Indoplanorbis F. C. B.\ker, Jour. Morph., LV, No. 1, pp. 1-12, phite 1-2. Type Platwrbis exustus Desh. Account of anatomy, especially genitalia and radula. As genus 1934. Indoplanorbis Pilsbry, Proc. Acad. X'at. Sci. Phil., 86, p. 54. Remarks on taxonomic position 1939. Indoplanorbis exustus Larambergue, Bull. Soc. Zool. de France, LXIV, No. 5, pp. 286-295. Anatomy and family position. As genus Shell (plate 79, figs. 33-35). Of medium size, sinistral, with few rapidly increasing whorls, the body whorl large and greatly increasing in diameter toward the aperture; spire whorls flat, depressed below the level of the body whorl; base with small umbilical opening, the inner whorls concealed by the last two whorls; aperture usually oblique, lips simple, sharp. Animal (plate 21, fig. 2). 'The animal is sinistral. Its foot is relatively broad and short, leaf-shaped, broadly rounded in front and pointed behind. 196 Family Bulinidae 197 The head is very broad and has its lower margin exi)anded and flattened. The tentacles are elongate and filiform. The eyes lie at the inner base of the tentacles and are completely sessile. The mouth opens on the lower surface of the head in front of the foot' (Annandale and Prashad, 1921, p. 578). See Rao. 1923. p. 200, for a more extended account of external characteristics. ANATOMICAL CHARACTERISTICS GENITALIA (plate 21, fig. 3). Male Organs. The seminal vesicle (SV) is about 4 nun. long and nearly 1 nun. wide and is composed of small lobes or tubercles surrounding the ovisperm duct. The si)erm duct (SPD) is a small tube 7 mm. long, the portion near the ovisperm duct folded or coiled. The prostate (PRS) is 3.5 mm. long and nearly 2 mm. wide, its low^r end broadly rounded, its upper end narrowed to half the diameter of the lower lobe. The prostate is composed of many long, branched diverticula, all of wdiich radiate fan-wise from the common meeting place of the sperm duct and vas deferens. In a cross section near the middle (fig. 8), there are shown eight primary diverticula each of which is branched three or four times toward the outer end, causing the outer surface of the prostate to show twenty-four or more rounded projections. Each diverticulum is branched as shown in fig. 9. The sperm duct and vas deferens meet on the lower side of the prostate, the prostate diverticula radiating outward from this junction. The ])rostate diA'erticula enter the sperm duct from which the vas deferens proceeds as a small tube less than half the diameter of the sperm duct. This condition is indicated in fig. 10. Both Rao and Larambergue describe the prostate as ellipitical in form, but it was of the shape figured in all but one of the specimens examined and the exception was regularly elliptical. There may, obviously, be some variation in the shape of this organ. In its natural position, the prostate lies against the uterus below the nidamental gland. The vas deferens is a very long, narrow tube (about 12 mm. long). The penial complex (fig. 3) is made up of a short, cylindrical preputium (3.5 mm. long) and a very long (17 mm.), narrow tube-like vergic sac (VS) , which is five times the length of the preputium. In the figure of Larambergue (1939, fig. 3, the vergic sac is shown four times the length of the preputium. In Rao's figure (1923, p. 215), the vergic sac and the vas deferens are confused and the enlarged vergic sac is entirely too short. The figure by Larambergue (fig. 1) shows the vergic sac too short and the preputium too long as compared with the specimens personally examined. There is a single retractor muscle (R^I) attached to the vergic sac near the summit of the prejmtium. A heavy nerve (N) innervates this muscle. Bands of supporting muscles (SM) are attached to the preputium on both sides. In Rao's figure (1923, p. 215), the retractor muscle is shown as at- tached to the vergic sac far above the preputium, which position was not observed in any specimen examined. Larambcrgue's figure ( 1939, p. 288) shows the muscle attached to the vergic sac just above the preputium, which appears to be its natural position. Internally (plate 21, fig. 1), the preputium contains two long, vertical, muscular pads or pilasters (]\IP) which extend the whole length of the preputial cavity. There is a small muscular ring or diaphragm between the vergic cavity and the preputial cavity. The verge (V) is a very long, nar- 198 The Molluscan Family Planorhidae row tube freely movable within the vergic sac (VS). This organ was en- tirely misunderstood by Rao and was not fully comprehended by the writer (Baker, 1933). Larambergue (1939, p. 288) correctly figures the relation- ship between the vergic sac (poche de penis) and the verge (tube penial), the latter being much longer than figured by Baker and extending the whole length of the vergic sac. The writer figured and described a bulbous swelling within the vergic sac (plate 21, fig. 1, B) which was thought to be the termination of the verge, the tube behind this swelling being considered as a part of the vas deferens. Larambcrgue's figure 2 (reproduced as fig. 2 on plate 73 of this work) shows that this is not the case and that the whole tube must be considered the verge. However, this bulbous portion of the verge was pres- ent in all specimens examined and a swelling of this region is shown in the figure of Larambergue where the long line for the symbol pe is directed. It seems probable that this bulbous portion (use unknown) is found in all examples of Indoplanorhis but in the specimens examined by Larambergue there was less contraction than in the specimens examined by Baker. In other words, the differences may be attributable to methods of preservation. Two specimens examined by Baker had the preputium completely everted from the male opening, the sac lying on the body of the animal, as shown in fig. 2 of plate 21. One of these specimens is shown in optical sec- tion in fig. 7 of plate 22. In this specimen, the preputium was greatly flattened so that the pilasters (AIP) became two flattened muscular pads, filling the greater part of the preputial cavity. The verge (V) and vergic sac (VS) extend through the preputium nearly to the opening of the preputium (PR). The bulbous portion of the verge is conspicuous and has moved downward. The retractor muscle is attached to the vergic sac near its distal end and the large nerve lies beside it (RM, N) . It is clearly evident that this muscle pulls back the male intromittent organ after copulation. A cross section of the preputium near its widest part is shown in fig. 6. The branching of the retractor muscle and the connections of the nerve are shown in fig. 5, greatly enlarged. The so-called supporting mus- cles of the preputium apparently become retractor muscles when the verge and the preputium are everted (fig. 5, plate 21). Larambergue (1939, p. 293) describes and figures the penial complex in the everted position (see plate 74, fig. 6). The vergic sac is shown ex- tended from the everted end of the preputium. The everted copulatory organ is enlarged at the distal end, being almost twice the diameter of the proximal end near the preputium. A trifle more than half of the length of the vergic sac is everted, the shorter portion remaining within the preputium and body during eversion. These drawings of Larambergue were made from freshly anesthetized specimens taken in coitus. Observations on the specimens dissected by the author do not entirely agree with those of Larambergue. In several specimens, the verge extended from the vergic sac and protruded into the perputium for some distance (plate 21, fig. 1). Rao (1923, p. 215) figures the verge (penis) as pro- truding from the vergic sac into the preputial cavity. He also figures the retractor muscle as attached to the vergic sac and not to the preputium. It has been the writer's opinion that only the verge was protruded from the end of the preputium when the latter was everted from the male open- ing. The retractor muscle is shown by Larambergue as attached to the upper end of the preputium, while in all specimens personally examined Family Bulimdae 199 this nmsclc, distally branched, was attached to the end of the vergic sac, as shown in plate 22, fig. 7. There are muscles on the preputiiun which probably aid in its retraction (plate 21, fig. 5). The writer believes that the bulbous swelling (shown at B in fig. 1, plate 21, and at B in fig. 7, plate 22) has some significance, for it is also shown, although in a more length- ened condition, in Larambergue's figure on page 288. It might be that it marks the limit of the copulatory portion of the verge, as suggested by the writer in a previous paj^er (1933, p. 4). The schematic figures 8 and 9 in Larambergue's paper (cojiied on plate 74, figs. 8, 9) suggest such a condition. As observed by Larambergue, however, these differences may be largely due to the preservation of the material examined. Female Organs (plate 21, fig. 3). Spermatheca (S) small (about 1 mm. long) pyriform, attached to the long, narrow vagina (2 mm. long) by a very short duct. The spermatheca is, in fact, almost sessile. The uterus (U) is about 5 mm. long and nearly four times as wide as the vagina. The large nidamental gland (NG) is 6 mm. long, is about as wide as the uterus and is curved about the uterus and oviduct. The oviduct (OD) is about as long as the uterus and vagina combined ( about 9 mm. long) . It is 1 mm. wide at the uterus end but decreases in diameter toward the albumen gland where it joins the sperm duct to form the ovisperm duct. There is a small carrefour. The albumen gland (AD, a flattened, more or less heart-shaped organ, is convex above and concave below. It has a narrow duct which enters the carrefour. The ovisperm duct (SO) is a narrow tube about 3 mm. long between the seminal vesicle and the oviduct. In the specimens examined it was entirely smooth, but Larambergue figures it as having lateral swellings, as was observed in some species of Planorbidae. A small, smooth duct about 1 mm. long joins the seminal vesicle to the ovotestis. The female organs are as figured in Larambergue's paper and also as described by Rao. The ovotestis (OT) appears on the surface as a multilobed organ. In cross section (near the anterior end) it is seen to be made up of seven or more main diverticula which branch twice at the outer end (plate 21, fig. 7). They radiate fan-wise from the ovisperm duct. Several branched diverticula contained ripe ova at their distal ends. The ova were dark gray in color and with these there were several small, rounded bodies which were red in color, evidently undeveloped ova. Respiratory and Renal Systems. The pseudobranch (figs. 4, 6, plate 21 ) is large and conspicuous and is not simply folded or leaf-like, as in all of the Planorbidae examined, but on the upper and lower surfaces of a leaf-like base are developed a number of projections with broad lobes, plaits, or folds (fig. 4) groujied together in series of three to six folds, each group of folds being separated from the other folds by a distinct depres- sion or gap. The base of attachment of the folds is not modified by the folded series (see fig. 6). In the living animal, the folded portion of the pseudobranch is turned back against the mantle edge. The rectum (R) is on the side above the pseudobranch and the anal opening is between the pseudobranch and the pneumostome. Rao ( 1923, p. 208) describes the lobes as occurring in groups of three or four, but in the specimens examined there were two groups of six each on the under side of the base and two groups of three lobes and two groups of two lobes on the upper side, as shown in fig. 6. The pneumostome (PS) 200 The Molluscan Family Plauorbidae is a large, thin lobe and is capable of considerable extension (fig. 4, PS). In fig. 2, it is shown turned back and sjiread open. The pseudobranch is highly vascular, well-supplied with blood vessels, veins, and muscles. It more nearly resembles the molluscan branchiuni than the pseudobranch of any of the other fresh-water pulmonates. The kidney is long and narrow (12 mm. long, 1.5 to 3 mm. wide). The ureter is 1.5 mm. long and is sharply reflexed against the lower part of the kidney, pointing backward and upward into the mantle cavity. In form, the kidney resembles that of Helisoma trivolvis figured on plate 44 (fig. 2). The reflexed ureter in the s})ecimens examined is not so long as figured by Rao ( 1923, p. 206) . A cross section near the middle (plate 45, fig. 19) shows a high, thick, wide ridge. The lumen is rounded and shows internal folds or septa. A large vein lies on each side of the lumen. The cross section somewhat resembles that of the kidney of Planorbarius corneus (plate 45, fig. 18). The kidney of Indoplanorbis is noteworthy for the size and width of the superposed ridge, which resembles some of the large Hclisotna species (as Helisoma pilsbryi, plate 44, fig. 12). Digestive System. The stomach resembles that organ in Australorbis glabratiis (i)late 48, figs. 9, 10). The intestine first makes a loop around the stomach, passes backward to the posterior part of the liver, then makes another loop and passes forward to the enlarged rectum, which has its exit in the anus above the pseudobranch. There is a narrow, low ridge on the rectum which ends near the pseudobranch. There is a large caecum or blind sac near the pyloric portion of the stomach. The buccal sac is short, wide, and high. Viewed from above, it is roughly heart-shaped. The radula sac is represented by a wide, flatly rounded bulge at the lower posterior extremity of the buccal sac. The two salivary glands are rather long, about one and a half times as long as the buccal sac when fully extended. In the natural position, the posterior ]iortion of tiie salivary glands (somewhat less than half the length) is floubled backward beneath the anterior portion, which is wider with larger glandular lobules. The ducts are short and narrow. The salivary glands are joined behind as in Helisoma and other planorbids. The jaws (plate 50, fig. 10) consist of a wide and low superior jaw, striated on its outer face, slightly bent downward at the ends. The lateral jaws are in the form of a question mark, are very narrow and about as long as the width of the superior jaw. The jaws of Indoplanorbis do not differ notably from the jaws of the subfamily Helisomatinae. The center tooth of the radula (plate 66, fig. 1) is higher than wide, rather narrow, the reflection broadly bicuspid and reaching nearly to the lower margin of the base of attachment. Lateral teeth (1-5), squarish, tricuspid, the mesocone the longest, the ectocone the shortest and i)laced high up on the reflection, all cusps wide and spade-shaped. Intermediate teeth (6-11) narrower, differing from the typical laterals in having a sec- ond small cus]) above the ectocone. The tenth intermediate tooth has two small cusps above the ectocone. Marginal teeth ( 12-26) narrow, about three times as long as broad. The entocone is split into three to five small, subequal cusps, the mesocone is larger and distinct, and the ectocone is smaller with two to three small cusps above it on the outer margin of the tooth. The outer marginal teeth (27, 32) are still narrower and the lower edge of the reflection is minutely denticulated. The extreme outer marginal teeth are very small (33) . Fcunilij Bulinidae 201 The nulula formula of Indoplanorbis is 33-1-33 with 140 to 150 rows of teetli. There is some variation among the different rows of teeth, prin- cipally in the nmiiber of accessory cusps in the marginal teeth. The radulae examined were remarkably uniform. The radula figured on plate 66 agrees with that described by Rao (1923, p. 204). The material examined consisted of six specimens from Hsipaw, North Shan State, Burma, collected by Dr. B. N. Choi)ra and Dr. H. S. Rao. The specimens were received from Dr. B. Prashad of the Zoological Survey of India. Geographical Distribution. The genus as represented by the type species, PUniorbis cxustus Desh., occurs throughout the plains of the Indian Empire east of the Indus, in Siam, the Malay Peninsula, French Indo-China, and-Sumatra (vide Annandale). For a more detailed account of the distribution of this group see Germain (1921, pp. 28, 29). The number of species or races referable to Indoplanorbis is in doubt. Germain (1921, p. 27) places almost everything under exustus as syno- nyms of that species. Planorbis coromandelicus Sowerby and Planorbis indicus Clessin have been thought to be distinct by some conchologists. A careful study of all names in connection with a large series of specimens from various localities might establish several recognizable forms. Remarks. The systematic position of Deshayes' Planorbis exustus has been a matter of interest for a number of years. It is the largest planorbid in India and the shell closely resembles certain species of the American genus Helisoma. An examination of its anatomy led Annandale and Pra- shad (1920) to consider it a new genus and Rao's investigations (1923) strengthened the view of its distinction as a generic group. Baker (1933) stated that it was 'one of the most distinct groups of the Planorbidae, its male complex exhil^iting characters not shared by any other group at present known.' Pilsbry (1934, p. 54) suggests its resemblance to Tropi- corbis, particularly in the form of the penial complex. ]\Iore recently Larambergue (1939, pp. 291, 294) argues that the genus Indoplanorbis is a group of the family Bulinidae. Little is known concern- ing the anatomy of the majority of the species of this family. Two species have been rather carefully studied, Bulinus contortus of Europe by Lar- ambergue ( 1939) and Isidora globosa from Portuguese East Africa by Connolly. In both of these species, the genitalia are similar to those of Indoplanorbis, especially in the form of the penial complex and the pros- tate (see plate 71, fig. 3 and plate 75 of this work). The most convincing characteristic is the pseudobranch, which is lobed in Bulinidae (Germain, 1931. p. 514). In Isidora globosa the lobed condition is well shown in Con- nolly's figure (plate 71, fig. 5, of this work.) The anomaly of a distinctly i^lanorboid shell in a group made up almost exclusively of physoid shells is no greater than is shown in the American subgenus Seminolina where one species, Helisoma duryi semi- nolina, contains all shapes of shell from distinctly physoid to normally planorboid. The shell of Indoplanorbis exustus is distinctly sinistral, par- ticularly so in the young and immature stages of growth. The writer agrees with Larambergue in the statement that the group Indoplanorbis is a distinct genus of the family Bulinidae, the deciding features being the lobulated pseudobranch and characteristics of the male genitalia, particularly the penial complex. X. GENERA WRONGLY REFERRED TO PLANORBIDAE Genus NAUTILINUS Mousson, 1872 Type by original designation, Hyalina clymene Shuttleworth 1872. Nautilinus Mousson, Neue Denksch. Allg. Schweiz. Gesell., XXV, p. 19. Type Hyalina clymene Shuttl. As subgenus of Hyalina 1921. Nautilinus Thiele, Archiv. fiir Mollusk., LIII, p. 111. Type Hyalina clymene Shuttl. Radula and generic position 1931. Nautilinus Thiele, Handbuch, Teil 2, p. 481. Type A. (N.) clymene (Shuttl.). As subgenus of Anisus This genus, based on a supposed land snail from Garachico, Tencrife, Canary Islands, is scarcely a member of the family Planorbidae, although so considered by Thiele. The figures given by Mousson (his plate 1, figs. 28-30, natural size, figs. 31-33 enlarged) do resemble some forms of Gyraidus. The shell is very small, only 2 nun. in diameter. Tryon (in Man. Conch., II, p. 172, 1886) places it in Zonitidae and says 'Its habitat is different from the Hyalininae generally, living in wet moss, associated with Physa, Ancylus, and Hydrocena, etc' Pilsbry (Man. Conch. IX, p. 24) lists it among the land shells. Wollaston (1878, p. 324) says 'I am ex- tremely doubtful whether this curious little Planorbis-likc shell should be associated with Hyalina.^ In 1921 (p. Ill), Thiele extracted a dried radula from a shell of this species and briefly described the teeth. The formula is 20-1-20. The center tooth is small and has one indistinct cusp. The side teeth (laterals and marginals) have four sharp ctisps. The single cusp of the center tooth re- moves clymene from the Planorbidae in which the center tooth always has two cusps. The form of the shell is distinctly unlike any form of the family Lymnaeidae, in which the center tooth of the radula is imicuspid. The radula resembles some groups of Ancylidae and Nautilinus might prove to be related to this family, perhaps in a similar manner to the American genus Neoplanorbis Pilsbry, in which the shell is particularly Planorbis- like. Only an examination of the anatomy of the animal, especially the genitalia, will definitely settle the question of the taxonomic position of Nautilinus. Genus PALAEORBIS Beneden and Coemans, 1867 1867. Palacorbis Beneden and Coemans, Bull. Acad. Belgique, ser. ii, XXII, pp. 385, 390 The only recent reference to this group, so far as known to the writer, is in Zittel's Grundziige der Palaontologie (Palaozoologie) , Abth. I, In- vertebrata, p. 424, w^iere the following comment is made: 'Hierhcr diirfte wohl auch die Planorhis sehr ahnliche Gattung; die zierliche Palaeorbis Bened. et Coemans em. Reis aus oberkarbonischen und permischen Ab- lagerungen von Europa und Nordamerika gehoren.' The name does not occur in any other edition of Zittel's work. The group is believed to include fossil Vermes, possibly Polychaetes. 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Haas wahrend der Schomburgh-Expedition in den Jahren 1931-1932. Abhand. der Senckenbergischer Xaturforsch. Gesellsch. Xo. 431. pp. 156. 8 Tafeln, 17 text figs. (1939). Malacological notes. The South American species of Planorbula. Zool. Series, Field Mus. Nat. Hist., XXIV, No. 8. pp. 93-103, figs. 7-9. 208 The MoUuscan Family Planorbidae (1940). Planorbulina not a generic name in the Mollusca. Nautilus, LIV, PI). 33-34. (1941). Obstructio versus Tropicorbis. Nautilus, 55, pp. 31-32. H.\l.\v.4ts, G. v. (1902). Die Fauna der Pontischen Schiehten in den Umgebung des Balatonsees. Resultate d. Wissensch. Erforsch. Balatonsees, Erster Band, Erster Teil, Art. II, pp. 1-8, plates 1-3, 7 text figs. Haldeman, S. S. (1841-1845). A monograph of the Limniades, or fresh-water univalve shells of North America. Continued as A monograph of the fresh-water univalve Mollusca of the United States, including notices of species in other parts of North America. Philadelphia, Pa. Published in nine numbers. (1841). Corrections . . . Genus Trochlea. American Jour. Sci., XLII, No. 2, p. 216. Hanna, G. D. (1922). Fossil fresh-water mollu.sks from Oregon contained in the Condon Museum of the University of Oregon. Univ. Oregon Pub., I, No. 12, pp. 1-22, plates 1-4. Hannibal, HAFiOLD (1912). A synopsis of the recent and Tertiary fresh-water Mollusca of the Californian Province, based upon an ontogenetic classification. Proc. Mai. Soc. London, X, pp. 112-166 (Part 2), pp. 167-211 (Part 3), relates 5-8. Hanley, Sylvanus, and Theob.\ld, William (1867). Conchologia Indica: Illustra- tions of the land and fresh-water .shells of British India. Pp. i-xviii, 1-65, i^lates 1-160. Hartmanx, J. D. W. (1840-1844). Erd-und Siisswasser Gasteropoden beschrieben und abgebildet von . . . St. Gallen. Published in 8 fascicles, I, 1840; II-IV, 1841; V-VI, 1842; VII, 1843; VIII, 1844. The 'Systematisches Ubersicht der Europa- ischen Gattungen' was probably published with the first part of this work. 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Fresh-water Biology. New York. (Chapter XIII, Parasitic flatworms, pp. 365-424, by Henry B. Ward.) Wenz, W. (1923). Gastropoda extramarina tetiaria. In Fossilium Catalogus I: Ani- malio, Pars 22, pp. 1421-1734. Edited by C. Diener. Berlin. White, C. A. (1883). The Molluscan fauna of the Truckee group, including a new form. Proc. United States Nat. Mus., V, pp. 99-102, plate 5. Westerlund, C. a. (1885). Fauna der in der Palaarctischen Region . . . lebenden Binnenconchylien. Lund, Fascicle V, pp. 135-|-14. (1899). Planorbis libanicus n. sp. Nachrbl. Deutsch. Mai. Ges., pp. 170-171. (1902). Methodus dispositionis Conchyliorum extramarinum in regione palaearctica viventium, familias, genera, subgenera, et stirpes sistens. Rad. Jugoslav. Akad., CLI, pp. 82-139. (1-58). WoLLASTON, T. V. (1878). Testacea Atlantica, etc. Pp. xi+588. London. Woodward, S. P. (1851-1856). A manual of the Mollusca. Published as follows: Pt. 1, pp. 1-158, 1851; Pt. 2. pp. 159-330, 1854; Pt. 3, pp. 331-486, 1856. Several subse- quent editions. (Raljih Tate has an appendix in 1869 in which Pompholyx appears.) Zittel, Ivarl a. von (1910). Grundziige der Paliiontologie (Palaozoologie). I. Abteil- ung Invertebrata. Neubearbeitet von Dr. Ferdinand Broili. Munchen und Berlin. x4-607 pp., 1414 text figs. THE MOLLUSCAN FAMILY PLANORBIDAE PART II THE PLANORBIDAE INHABITING NORTH AND SOUTH AMERICA AND THE WEST INDIES* *It was Mr. Baker's plan that Part II should contain full morphological and taxonomic descriptions together with comprehensive illustrations of the shells of all species of the Planorbidae known for North and South America and the West Indies. His voluminous working notes were not near enough objective organization at the time of his death to permit their being edited for publication. Any attempt at preparation of these notes by another hand could not ensure the reflection of Mr. Baker's matured judg- ment and ultimate intent in the casting of specific descriptions, in the portra.yal of indi\idual variability, and in the discussion of geographical distribution and ecological relationships. However, at the time of his death, he had completed fifty-four of the plates intended for this section and had prepared typewritten copy for them. In his desk were found plainly-marked photographic prints of other species sufficient to pre- pare six additional plates and pencil manuscript for descriptions of the figures had been written out. The entire group of sixty plates (82-141) is included as a supplement to Part I, even though the six plates at the end of this series represent working copy in which he might have desired to make some final alterations. For convenience of arrangement and reference, the plates of Parts I and II are presented in a single undivided series at the end of this monograph. In addition to the plates for Part II, descriptions ha\'e been prepared for nine new species and seventeen new varieties. The foreword was written by Professor Harley Jones Van Cleave, who also assembled and edited the descriptions of the new forms and edited the explanations of the plates.— H.E.C. XII. FOREWORD FOR ALMOST A QUARTER OF A CENTURY, Frank Collins Baker had been engaged in the preparation of detailed descriptions of the species and critical evaluation of the synonymy of the Planorbidae of the Western Hemisphere. This study was the natural outgrowth of the long years of detailed morphological studies which led him to the evalua- tion of anatomical detail as expressed in the broader phases of taxonomy in the main body of the present volume. The second volume in this series was to have treated the species of the Planorbidae in a manner similar to his treatise on another large and important family of fresh-water snails, the Lymnaeidae. Though published in 1911, his volume on the Lymnaeidae of North and Middle America after more than thirty years still stands as the leading taxonomic and distributional study of the lymnaeid snails of the Western Hemisphere. Though such a program of study involved intimate familiarity with the voluminous, scattered literature and wise interpretations of matters of dis- puted priority and synonymy, these labors paled into insignificance when compared with the self-imposed task of dissecting and microscopically studying representatives of all the species available through the well- recognized repositories of collections. To these customary sources were added large quantities of material from individuals throughout the world with whom kindly cooperation had established intimate personal and pro- fessional contacts. Large numbers of dissections and long series of shells gave opportunity for bridging the gap between the earlier field of Con- chology and the newer science of Malacology to both of which Mr. Baker had made notable contributions. As he reached final decisions on the validity and synonymy of the species in the various genera, he prepared photographs of the shells or of original drawings of the type specimens wdien shells were not available. These photographs he arranged as plates and for each he prepared a detailed descriptive legend. He had com- pleted plates illustrating the shells of the genera HeUsoma, Carinijex, Parapholyx, Planorhula, Menetus, Drepanotrema, Tropicorbis, and Ta- phius. In his office at the time of his death were hundreds of photographic prints of other genera and species intended for use in this monograph. Some of these he had so marked and keyed with numbers that it has been possible to assemble six additional plates which are included at the end of the series. With this inclusion, all of the genera which he apparently intended to figure are included though many of the species are not por- trayed in the detail which he established in those earlier parts which he had completed. The explanations of plates 136 to 141 are compiled from rough pencil notes and must be accepted as the author's tentative arrange- ment of work in progress which might have been changed somewhat in the final editing. Some of the species not included in the plates of the api:)endix have representative shells figured on plates 72 to 81 of the illustrations for the body of the monograph. However, these figures are usually of only the type species in each genus and do not carry out the plan of comprehensive comparisons set for the second section of the monograjih as originally projected by the author. 215 216 The Molluscan Family Plauorbidae In the sixty plates included in this appendix (plates 82 to 141), many type specimens and other critically determined materials are figured, and information as to the present whereabouts of these critical materials is made available. In the members of the family Planorbidae, where syn- onymy has been so involved and w^iere intergradations in shell characters have been so confusing, the interpretation of range of individual vari- ability by one who has devoted years to the study and had the singular advantage of access to all the important collections, will be appreciated by all naturalists who have the need for studying snails. For convenience of reference, the plates in the appendix are numbered in direct continuation with the series of plates in the body of the mono- graph. In the explanation of the plates, the repository of the figured speci- mens is usually indicated by the following abbreviations: A.N.S. — Academy of Natural Sciences of Philadelphia B. — Frank Colhns Baker Collection C.A.S. — California Academy of Sciences M.C.Z. — Museum of Comparative Zoology, Harvard University U.C. — University of Colorado Museum U.I. — University of Illinois, Museum of Natural History U.M. — University of Michigan Museum U.S.N.M. — United States National Museum In connection with the foregoing list of repositories, it should be here recorded that the Frank Collins Baker collection of fresh-water snails and the specialized library accompanying it, after his death, was deposited in the United States National Museum. This was in keeping with his ex- pressed desire. It should be further explained that the collections attributed to the University of Illinois are designated by two series of letters. Those 'U.I.' entries having the letter 'Z' preceding the accession numeral are in the zoological research collections of the Museum of Natural History in the University of Illinois. Paleontological specimens, indicated by inser- tion of the letter 'P' immediately before the accession number, are now deposited in the Paleontological Collections of the Illinois State Geological Survey, in Urbana, Illinois. Citations of magnification in the explanation of the plates are usually only approximate. In final preparation of the cuts, it was in many in- stances unavoidably necessary to make slight modification of the author's indicated amount of reduction from the original plates so as to conform to the available page size. In listing the names of the species in the explanation of plates in the appendix, Mr. Baker placed the name of the author of the species imme- diately after the specific name and frequently gave no indication by the use of parentheses in instances where the si~)ecific name was recombincd with a generic name other than that to which the species was originally ascribed. It should be recalled that the preliminary draft which he pre- pared was never finally edited by him. Through the very generous cooper- ation of a number of the most widely recognized American authorities in the study of the Mollusca, the use of parentheses for author names has been carefully checked. Some errors or inconsistencies may yet be found because the literature is extremely scattered and there are no compre- hensive check lists of the species of Planorbidae. As previously explained, the manuscript for the section in which Mr. Baker had expected to provide full descriptions of all species and varieties Foreivord 217 of the Plan()rl)i(l;R' of the New World had never been c()mi)leted. In the vohnninous long-hand notes which he left in unfinished fonn, there were included the preliminary drafts of descriptions of many new species and new varieties intended for incorporation in Part II. After it had been de- cided that the plates for Part II should be included as an appendix to the morphological studies, it was discovered that the legends for these plates made frequent reference to previously unpublished specific and varietal names. His manuscript descriptions for many of the new species and new varieties were so well organized that there could be no doubt regarding his intention. Consequently, liis jireliminary descriptions have been edited and are included as a separate section of Part II. A few of the varieties and species which he tentatively considered as new could not be found in his files. For these it is assumed that he had never prepared definite de- scriptions. In order to avoid nomenclatorial difficulties, these names have been deleted to prevent their becoming nomina nuda. In each such in- stance the undescribed and unnamed form has been referred to under its proper genus as a questioned species or questioned variety. XIII. DESCRIPTIONS OF NEW SPECIES AND NEW VARIETIES AS EXPLAINED in the foreword, the following technical descriptions AA of new species and new varieties were edited from longhand notes -*- ■*- prepared by Mr. Baker. During the past quarter of a century he examined every important collection of Planorbidae housed in the museums of America and received extensive field collections from many private collectors as well. In the handling of this huge quantity of material he came to recognize fundamental likenesses and differences at vaiying levels. In addition to his study of the shells, his intensive work on the morj^hology of the snails gave him a broad background for the recognition of natural groups. On the one side, he expressed his conclusions in the broad new classification of the Planorbidae as set forth in Part I of this volume. There he evaluated the characteristics on which families, subfamilies, genera, and subgenera may be recognized with safety. On the other side, his attention to the limits of individual variation in characteristics of the shell furnished the basis for the detailed recognition of specific and varietal boundaries. The descriptions of new forms and the redescription of all known species were to have been the final goal of Part II of this study. From his incomplete notes the following descriptions include only those for which he had prepared tentative definitions. On other species and varieties, which he obviously thought of as new, he had not committed himself through the preparation of manuscript notes and in the assembly of illustrations. The descriptions of nine new species and seventeen new varieties are arranged in the same sequence of genera and subgenera as outlined in Part I (see pages xiv and xv of the Contents) . All tabular arrangements of shell measurements are expressed in millimeters. GENUS Tropicorhis Tropicorhis shivtieki, New Species Plate 134, figs. 12-14, 28 Shell solid, small, of three and one-half whorls. Upper surface showing three and one-half whorls which are subangulate above, sutures very deep. Lower surface showing three and one-half whorls which are subangulate in the middle, sutures very deep. Whorls rounded on the i)eriphery. Apical whorls sunken on both surfaces. Whorl slightly deflected at aperture. Aperture Innately rounded, outer lip thick with callus. A callus on parietal wall connecting the extremities of the outer lip. Sculpture of coarse growth lines with fine spiral lines. Apertural lamellae six, those of sigmoid form extremely short and thick, only slightly more than half the length of those found in obstructus. Shell Height Greater Diameter Lesser Diameter Aperture Height Aperture Diameter 1.5 1.6 1.5 4.0 3.8 3.4 3.2 3.1 2.8 1.1 1.1 1.1 1.0 1.1 1.0 Holotype Paratype Paratype 218 Descriptions of New Species and Xew Varieties 219 Type Locality. Ometopc, Nicaragua. Type Material. Collected by B. Shimek in 1893. Four specimens de- posited in United States National ]\luseum, Accession no. 534290. The holotype is shown on plate 134 as fig. 12; figs. 13, 14 are paratypes. Tropicorbis shimeki resembles albicans but is smaller, has a greater axial height, and has subcarinate whorls. The parietal lamellae are dis- tinctly shorter and thicker than in other forms of the genus. T. shimeki is smaller than declivis and its axial height is greater; it also has deeper sutures than are found in declivis. Additional representatives of T. shimeki were collected by Orcutt in Coatzocoales, Mexico (United States National Museum, Accession no. 219696). This species is named in honor of Professor B. Shimek. GENUS Helisoma Helisoma anceps anticostianum, New Variety Plate 96, figs. 18-22 Shell differs from typical anceps in the low axial height, the wide and shal- low spire depression with bluntly angular carina, and the shallow and wide umbilical region of the new variety. The aperture is but slightly expanded. "Whorls about four, evenly and regularly coiled, with faint spiral lines. Shell Greatest Aperture Aperture Height Diameter Height Diajneter 4.7 10.0 3.7 3.0 Holotype 6.0 12.5 4.8 3.6 Paratype 4.8 9.5 3.7 2.9 Para type Type Locality. English Bay, Anticosti Island. Quebec, Canada. Type Material. Collected by AV. S. Brooks, September 15, 1919. The holotype is shown on plate 96 as fig. 18; paratypes as figs. 19 to 22. De- posited in the collection of the Museum of Comparative Zoology, Harvard University, Accession no. 48285. H. anceps anticostianum, a Pleistocene fossil, is similar in appearance to striatinum from ^Milwaukee, but differs in the fact that the new variety has wider and shallower spire depression, has general lower axial height, and lacks distinct angulations above and below. All of these features are marked in striatinum. The whorls are likewise flatter above in the new form than in striatinum. Spiral lines are not notably distinct. Some speci- mens have evidence of a former campanulate lip. Helisovna anceps hartschi, New Variety Plate 83, figs. 19-22 Shell compressed, with four whorls. Periphery rounded. Spire depression wide, a wide cone with flat sides; shallow, bordered by a well defined carina. Base with flattened whorls, the carina sharp and placed near the outer edge. Surface of shell shining, growth lines very fine; occasionally white varices on whorls. Sculpture of very faint spiral lines. Aperture in- verted ear-shaped, forming a sharp V above and a broad V below. Outer 220 The Molluscan Family Planorbidae lip thickened and expanded, white, bordered by reddish band inside. Parietal wall with white callus. Shell Maximum Aperture Aperture Height Diameter Height Diameter 6.5 11.7 5.5 3.3 Holotvpe 6.1 12.0 5.1 3.0 Paratvpe 6.6 11.6 5.5 3.3 Paratype Type Locality. Brook at Great Falls, Virginia. Collected by Soelner. Type Material. Holotvpe and seven paratypes, deposited in the United States National iMuseum, Accession no. 227858. Holotvpe figured on plate 83, fig. 19; paratypes figs. 20-22. This variety may be distinguished by its small axial height, depressed shape, wide and shallow spire depression, flat basal whorls with carina near periphery. It resembles the variety poUtum from Canada, but that variety has rounded basal whorls without marked carina, its spire depres- sion is wide with more flat-sided whorls, and dorsal carina is more acute. The basal part of the aperture is rounded or almost flat in politum, but has sharp, wide angle in bartschi. Bartschi differs from sayi in lower axial height, less sharply angled basal whorls (with carina not near edge as in sayi) ; shallow and wide spire depression. Bartschi differs from anceps in lower relative axial height (compared with diameter) ; wider spire depression; basal whorls flatter; carina nearer periphery (near center in anceps). Helisoma anceps bartschi is apparently a common form in the Potomac drainage. Helisoma anceps idahoense. New Variety Plate 84, figs. 26-28 Plate 101, figs. 11, 12 Spire with carina in center. Base concave, basal whorls flat to sutures which are well marked. Whorls four. Spire depression deep and funnel- shaped, the whorls flat-sided. Carina well marked. Whole shell is cone- shaped, the whorls sloping upward to the spire carina. Color yellowish horn. Sculpture of regular growth ribs crossed by distinct spiral lines. Aperture auriform (reversed), sharply angled above, flat or flatly-rounded below. Lip sharp. Distinct columellar callus. Color of aperture whitish or slightly purplish. A callus often within the lip edge. Shell Height Maximum Diameter Aperture Height Aperture Diameter 11.0 8.5 9.5 18.0 15.6 15.5 9.5 7.5 8.6 6.0 6.0 6.2 There is considerable variation in width and depth of spire depression. Base rarely rounded, without carina. Carina always near center of base. Some variation in shape of aperture. It may form a sharp V below (as in the holotype) or it may be rounded and flattened at this point. This- variety is nearest to latchfordi, differing in the less angular basal portion of the aperture and also in the more distinct and heavier spiral sculpture in idahoense. Descriptions of New Species and New Varieties 221 Type Locality. Pend Oreille River, Sand Point, Idaho. Type Material. Holotype (plate 84, fig. 26) and paratypes in r. C. Baker Collection, no. 1863, now deposited in United States National Museum. H. anceps idahoense is apparently common in Idaho and Alontana. In some places it occurs on muddy sand or on old logs. HeXisoTTia anctps ^oliiutn. New Variety Plate 83, figs. 16-18 Shell flattened, ^vider than high, spire deeply sunken, showing three and one-half to four whorls, the depression widely cone-shaped rising to a vaguely defined, rounded carina. Umbilical region flattenecl, showing three and one-half to four whorls, the front half of the body whorl with a faint ridge about in the center of the whorl. Ridge disappears on the last third of the body whorl which is rounded. Sculpture of fine, thread-like riblets, often raised into slight ridges, especially toward the aperture. Color of shell pale yellowish to dark brown. Surface polished in living specimens. Fine impressed spiral lines present in all specimens examined. Aperture ovate, higher than wide, obtusely angled above, straight or but slightly curved below. Outer lip thickened, bordered within by a reddish-brown band. The lip edge is white on the outside. Shell Height Maximum Diameter Aperture Height Aperture Diameter 8.1 8.1 8.0 15.0 14.0 14.2 7.0 7.0 7.0 4:A 4.0 4.0 Holotype Paratype Paratype Type Locality. Honeywell Creek, Carleton Co., Ontario, Canada. Col- lected by F. R. Latchford. Type Material. Deposited in United States National Museum, Acces- sion no. 367426. Holotype figured on plate 83, fig. 16; figs. 17, 18 are paratypes. H. anceps poUtum is related to unicostatuui but the new variety has a wider and shallower spire depression, a more compressed shell, and a distinct carina on the basal whorl, besides having the surface of the shell ix)lished. Latchford identified this material as unicarinatum. Helisoma hinn&yi randolphi, New Variety Plate 94, figs. 1-8 Shell differing from typical binneyi in being of less axial height, the carina surrounding the spire depression is obsolete or faintly developed; the basal whorls are rounded, not angulated. Sculpture is fine with the ribs close together, both being very much finer and closer together than in binneyi. The lip is only slightly expanded. ^Mature shells have four whorls. Shell Maximum Aperture Aperture Height Diameter Height Diameter 11.8 20.8 10"2 7.3 Holotype 11.0 20.8 10.3 6.5 Paratype 9.1 17.1 8.5 5.0 Paratype 9.2 15.9 8.2 5.5 Paratype 7.6 12.4 7.0 4.1 Immature 222 The Molluscan Family Plauorbidae Type Locality. Lake Wasliington, Seattle, Washington. Type Material. Collected by P. B. Randolph, deposited in United States National Museum, Shimek Collection, Accession no. 504360. Holotype figured on plate 94, fig. 1; paratypes, figs. 2-4; immature, fig. 5. Helisoma carihaeum cuhense. New Variety Plate 119, figs. 22-25 Shell differing from that of typical caribaeum in having the spire depres- sion much narrower, the whorls, especially the body whorl, increasing more rapidly in diameter. Five full whorls. Sutures not impressed as in caribaeum, the spire whorls flattened, not rounded, and there is often a carina at the edge of the whorls. Nuclear and first whorl rounded as in caribaeum and of the same size. Basal whorls rounded, the umbilical region concave, umbilical opening distinct. Axial height somewhat greater than in typical caribaeum, the body whorl flattened near the spire depres- sion, not evenly rounded as in typical caribaeum. Aperture more nearly auriculate than in caribaeum, the lip sometimes (as in the holotype) thickened by a heavy callus. Sculpture as in caribaeum. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 8.7 19.1 16.0 6.0 4.0* Holotype 7.0 16.0 13.5 6.2 4.0 Paratvpe 6.1 14.0 12.0 4.5 3.0 Paratvpe 6.0 14.1 11.1 4.3 3.1 Paratvpe *.A.perture contracted in holotype liy thickened lip. The form of the whorls increases like that of tenue, especially like that of tenue sinuosum, but inner whorls are like those of caribaeum in that they are rounded, and are not like those of tenue which are flat and cari- nated at the edges. Some living Cuban specimens have a somewhat nar- rower spire than the typical form here figured but these lack the greatly increased diameter of the body whorl characteristic of cubense and the aperture is not auriculate or thickened by a callus as in mature and nearly mature specimens of cubense. The basal whorls are more concave than in caribaeum. Sutures are not as deep as in caribaeum. Evidently a Pleisto- cene fossil. Type Locality. Zapata Swamp, Cuba, in marl between layers of peat. Type Material. Eight specimens, collected April 19, 1927, by H. H. Bennett, are deposited in the United States National Museum, Accession no. 404719. Of these, the holotype is figured on plate 119 as fig. 22, and three of the paratypes are shown as figs. 23-25. HeXisoma colum\)ie.n&e.. New Species Plate 119, figs. 16-21 Shell with four to four and one-half whorls, rapidlv enlarging. Spire de- pression flattened, the inner whorls bordered by a sharp carina which be- comes distinctly central in position on the last whorl. The sides of the depression slope sharply downward. Base of shell concave, broadly funnel- shaped, the last whorl with a more or less sharp carina or ridge. Sutures well marked. Sculpture of coarse riblets, widely spaced, as in typical sub- Descriptions of Xew Species and New Varieties 223 crenatum. Aperture ovately rounded, the li)) riiu thickened and broadly reflected. A callus on the parietal wall renders the aperture continuous. There is usually. a border of dark chestnut or reddish brown within the aperture. The aperture may be rounded above or there may be a sharp V-shaped angle, depenfling upon whether the dorsal carina is sharp or rounded. There is normally an indication of angulation at this point. The basal part of the aperture is flatly rounded. Several old lip expansions may show on the body whorl back of the aperture. Color whitish, tinged with chestnut in some specimens. Shell Height Shell at Greater Lesser Aperture Aperture ieight* Aperture Diameter Diameter Height Diameter 8.5 10.5 18.5 14.6 8.5 6.5 Holotype 10.0 10.5 19.0 15.5 9.3 6.2 Paratype 9.5 11.0 19.0 15.5 10.0 6.5 Paratype 9.5 10.0 17.6 13.6 9.0 6.5 Paratype 9.1 11.0 17.0 13.1 8.1 6.0 Paratype ♦Measurement taken behind the expanded lip. Type Locality. Lac La Hache, Cariboo District, British Columbia. Type Material. Fifteen specimens, collected by H. and R. D. Svihla, are deposited in the Museum of Comparative Zoology of Harvard Uni- versity, Accession no. 93710. The individual selected as holotype is shown on plate 119 as fig. 16; paratypes as figs. 17-21. Helisoma columbiense shows relationship to the binneyi group in its sculpture and the carination of its whorls. It differs from the members of that grou}) in that it is of smaller size, has less relative axial height, its rib striae are less widely spaced and the whorls are usually more angulate. It differs from the subcrenatum group in having more regular and less widely spaced rib striae, in its angulated base and spire depression, and in the shape of the aperture. Helisoma hennicotti, New Species Plate 89, figs. 13-17 Shell in four whorls, rapidly increasing in diameter. Body whorl axially very high. Sculpture of evenly spaced, rather heavy, rib-like growth lines becoming more widely spaced on the last half of the body whorls. Spire depression concave, widely cone-shaped, flat-sided, bordered by a strong, sharp carina, extending to the aperture. Base showing three whorls, the umbilicus deep, with a small perforation; only slight indication of a carina in adult, but distinct and sharp in immature specimens. Aperture auriform, sharply angled above, flatly rounded and effuse below, the outer lip ex- panded. Parietal wall with a thin wash of callus which connects the ex- tremes of the lip. Color light, yellowing horn, brownish or bluish in some specuuens. Height at Diameter at Shell Greater Expanded Expanded Aperture Aperture Height Diameter Lip Lip Height Diameter 12*5 19.0 14.2 20.2 12.0 6.6 Holotype 12.0 17.1 14.0 18.5 11.5 6.5 Paratype 12.5 18.1 14.2 19.4 12.0 5.5 Paratype 7.5 11.0 9.0 12.0 7.0 4.0 Immature 8.0 11.0 9.0 12.0 7.0 4.1 Immature 224 The Molluscan Fainily Planorhidae Helisoma kennicotti is a very distinct species. It differs from injra- carinatum in its smaller size, greater relative axial height, as compared with diameter. Expressed in percentages of height to diameter, kennicotti is sixty-five per cent and infracarinatum, fifty-six per cent. The spire de- pression is much smaller, narrower, and deeper in kennicotti, the shell forming an inverted cone. The base of the new species is likewise narrower, and the whorls dip into the umbilicus at a sharper angle, only one and one-half turns before entering the umbilicus. In contrast, in infracarinatum tliere are two full turns visible. Type Locality. Lake Isle la Crosse, English River, Canada. Type Material. Deposited in United States National Museum, Acces- sion no. 29231, bearing the label of the old Binney collection no. 9272 and there recorded as Planorbis trivolvis. Figures on jilate 89; holotype as fig. 15; paratypes as figs. 16, 17; 13, 14 immature shells. Helisoma pilshryi prehlei. New Variety Plato 91, figs. 6 to 8 Helisoma pilsbryi prehlei differs from typical pilsbryi in its greater relative height in comparison with diameter of the shell. The whorls in prehlei are more tightly coiled, the body whorl increasing more rapidly in diameter, causing the spire depression and umbilical region to appear smaller than in pilsbryi in which the whorls are rounded more regularly. The aperture is widely expanded to form a reflected lip. This is not true of pilsbryi. Whorls, four and one-half. Sculpture as in pilsbryi. H. p. preblei differs from subcrenatum in absence of all indication of a carina on the umbilical side. The whorls of the spire depression are subangulated, not sharply angled as in infracarinatum. Height Diameter at at Expanded Expanded Lip Lip 17.0 27.0 16.0 26.0 *Bioken specimen with four and one-fourth whorls, the last one-half whorl broken away. Type Locality. Knee Lake, Manitoba, Canada. Type Material. Three specimens, collected by E. A. Preble in the 'North West Territory, Knee Lake, Keewatin,' deposited in United States National Museum, Accession no. 180279. Figured on plate 91, holotype as fig. 6; paratypes as figs. 7, 8. The type material was i:)reviously called infracarinatum but it is nearer to pilsbryi. It differs from the latter in its expanded lip and more tightly coiled whorls of the umbilical region. Differs from infracarinatum in the absence of a basal carina and in having a narrower and more sunken spire depression. Helisoma subcrenatum perdisjunctum^. New Variety Plate 96, figs. 13-17 Shell small, horn colored; whorls three and one-half to four, discoidal, evenly rounded; 3 whorls below. Whorls slowly increasing in diameter, rounded above and below, not carinated. Sculpture of distinct growth lines, Shell Greater Height Diameter 14.0 24.5 14.0 25.0 11.5 19.0 Aperture Height Aperture Diameter 13.0 13.0 9.5 7.0 7.5 5.6 Holotype Paratype Paratype' Descriptions of Xeiv Species and Xeiv Varieties 225 finer than in disjunctum. Aperture rounded above and below, slightly ex- panded where it joins the body whorl. A distinct callus on the parietal wall, often making the aperture and lip continuous. A slight thickening inside outer lip, bordered by brown band. Shell Greater Aperture Aperture Number {eight Diameter Height Diameter of Whorls 4.0 8.5 3.7 2.6 4.0 Holotype 4.6 9.2 4.1 3.0 3M Paratype 5.0 9.0 4.7 3.2 3M Paratype 5.2 10.5 4.9 3.2 4.0 Paratype Type Locality. Yellowstone Lake, Wyoming. Type Material. Five specimens, collected by Dr. Curtis, deposited in the United States National Museum, Accession no. 30207a. Holotype here shown as fig. 13 on plate 96; paratypes as figs. 14-17 on same plate. H. s. per disjunctum is similar to disjunctum but is much smaller, about the size of oregonense, but lacks the characteristic shape of the aperture of the last named form. The dorsal carina and the more uniformly and evenly coiled whorls, without rapid increase in size distinguish it from oregonense. Appears at first like immature disjunctum but is uniformly smaller; never has the axial height of disjunctum. ]\Iany specimens have lost the epi- dermis, exposing white, chalky shell. HelisoTTia trivolvis marshalli, New Variety Plate 87, fig.s. 11-15 Shell compressed, whorls four and one-half, rapidly increasing in diameter, the body whorl notably expanding toward the aperture. Sutures well marked above and below. Sculpture of coarse lines of growth, thread-like; spiral lines very indistinct or wanting. Spire depression small, narrow, shallow (less than one-half the width of whorl) , its border rounded, with- out carina in adult specimens, carina slightly developed in young and immature specimens. Spire flat in young individuals. Ventral surface flat- tened, the whorls coiled in one plane in mature specimens, three whorls visible, the umbilical whorls with a more or less acute carina. Sutures deep. In young and immature individuals the carina is sharp and the basal whorl about the umbilicus is raised to form an inverted V; whorls rounded ven- trally in half grown and immature specimens. Aperture wider than high, long oval, the dorsal margin forming an inverted V near junction with body whorls; the ventral margin flat, straight, extending well beyond the position of the dorsal margin on the body whorl. Outer lip sharp, with slight thick- ening within, margined by reddish line. Surface of shell light or dark horn. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 5.9 14.8 11.5 5.0 4.7 Holotype 6.0 13.0 10.8 5.0 4.1 Paratype 5.8 14.0 11.9 4.9 4.5 Paratype 5.4 11.0 8.6 4.8 3.5 Immature 4.9 10.2 8.0 4.2 3.3 Immature Helisoma trivolvis marshalli differs from jallax in that the new variety has the body whorls more expanded toward the aperture; the dorsal de- pression is smaller; color is light or dark horn, not greenish; the aperture is wider and more ovate. 226 The Molluscan Family Planorbidae Type Locality. Washington, D. C. Type Material. Collected by Foreman, deposited in United States National Museum, Accession no. 124989. Holotype on plate 87 as fig. 13; paratypes as figs. 11 and 12; figs. 14 and 15 of immature shells. In addition to the type locality, H. t. marshalli has been identified in collections from various localities in Maryland, New York, New Jersey, and Virginia. HelisoTTia campanulatuTn dalli, New Variety Plate 111, fifis. 12. 13, 15, 16 Shell resembling michiganense in the low axial height, but the body whorl is irregularly coiled and overlaps the penultimate whorl. Five whorls, upper whorls irregular; blunt carina on upper whorls. Four whorls showing on base, base 'reamed out' similar to that of rudentis, and whorls irregular. Umbilicus much smaller than in rudentis and also smaller than in michi- ganense. Lower whorls rounded. Sculpture and aperture as in michiganense. Shell Maximum Lesser Aperture Aperture Height Diameter Diameter Height Diameter 6.2 15.0 11.6 5.5 4.0 Holotype 5.4 14.1 11.0 4.7 4.0 Paratype 5.5 14.1 11.5 5.0 3.6 Paratype 6.1 14.9 11.6 5.3 4.0 Paratype Type Locality. Anticosti Island, Quebec, Canada. Type Material. Collected by Dr. J. Schmitt, deposited in United States National Museum, Accession no. 162724. Holotype, plate 111, fig. 12; para- types, figs. 13, 15, 16, five others not figured. Differs from other varieties in irregularly coiled body whorl which con- spicuously overlaps the preceding whorls. Base is not excavated, but whorls are irregularly coiled as in spire. Axial height less than in rudentis. Helisoma cainponidatu))i dalli is known only from marl deposits. Helisoma campanulatum pleistocenicmn, New Variety Plate 110, figs. 21-26 Shell small, whorls four, the inner spire whorls tightly coiled and gradually increasing in diameter, the last whorl rapidly increasing in diameter. The spire depression occupies about thirty per cent of the greater diameter of the shell while in campanulatum campanidatum it occupies about forty per cent of the greater diameter of the shell. Sutures w^ell impressed. Base with two to two and one-half whorls visible, the whorls tumid. Umbilicus large for the size of the shell. Aperture strongly cami^anulate, the campanu- lation beginning a considerable distance back of the aperture. The small diameter of the spire depression and the rapidly enlarging body whorl serve to distinguish this variety from all other forms of campanulatum. This form is distinctly different from the Pleistocene cayn- panidatum of the middle west. Type Locality. White Pond, ]\Iarlsboro, Warren Co., New Jersey. Type Material. Holotype (figured on plate 110, fig. 21) and eight para- types (five shown on plate 110, figs. 22-26) are in the Lea Collection in the United States National Museum, Accession no. 121195. Descriptions of Neiv Species and N'eiv Varieties 227 Helisoma campanulatum rideauense. New Variety- Plat (> 109, fig.^. 21-24 Shell very large, of five whorls, spire flattened, the inner whorls raised slightly above the body whorl; sutures deeply marked. Base with three to four whorls visible, rounded, in same plane, not reamed out as in dalli and rudentis; sutures well marked and whorls rounded. Umbilicus small, deep. Aperture as in campanulatum. Sculpture of heavy, evenly spaced riblets, but not as heavy as in wisconsinense ; about as in some individual shells of ca»ipanulatiuu. In the following table the measurements were taken just behind the aperture, which is constricted and then dilated. Shell Height Greater Diameter Lesser Diameter Aperture Height Aperture Diameter 6.5 7.0 7.0 6.8 19.6 18.5 18.0 17.5 15.0 14.1 14.0 13.0 6.5 6.5 6.3 6.3 6.0 5.1 5.1 5.4 Holotype Paratype Paratype Paratype H. c. rideauense differs from michiganense in the former's larger size, smaller umbilical opening, and greater axial height. Surface is dull, not shiny, caused by the heavy scul]:)ture. Color bright horn. The aperture is more distinctly campanulate than in michiganense . Type Locality. Rideau River, Ottawa, Canada. Type Material. Five specimens, collected by F. R. Latchford, deposited in the United States National ]\Iuseum, Accession no. 346627. Tlie holotype is shown on plate 109, fig. 21 ; paratypes, figs. 22-24. GENUS Farapholyx Parapholyx effusa dalli. New Variety Plate 115, figs. 27-30 Three whorls, rounded. Color greenish horn. Spire slightly raised, sutures well marked, deep on last whorl. Sculpture of strong, erect, membranous ribs, thirteen to fifteen on body whorl, equidistant or widely spaced. Very fine lines of growth between ribs, spiral lines obsolete. Ribs usually absent on spire whorls. The ribs produce spaced, vertical depressions inside aper- ture. Aperture rounded, acute below. Columella narrow, concave, either contpletely closing the umbilicus or leaving a small narrow and long chink. A thin wash of callus on the parietal wall. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 4.9 5.0 4.8 3.9 3.3 Holotype 5.0 5.0 5.0 4.0 3.3 Paratype 5.0 6.0 5.0 4.1 3.2 Paratype Parapholyx effusa dalli differs from all other forms of the genus in the presence of membranous ribs which stand up, either at an angle or verti- cally, as leaf-like frills, very thin and easily broken off. The ribs in costata and other costate forms of the genus (as costate specimens of klamath- ensis from Klamath Falls) are simply rounded ribs, enlargements of the lines of growth. These do not affect the inside of the aperture. In dalli, on the contrary, the ribs appear as vertical creases on the inside of the aper- 228 The Molluscan Family Planorbidae ture. Some individuals of costata may have slightly membranous ribs, but these are never like those of dalli. Type Locality. Klamath Falls, Oregon. Type Material. Seventeen specimens, collected by Henshaw, are de- posited in the United States National Museum, Accession no. 219749. The holotype is figured on plate 115 as fig. 27; paratypes as figs. 28-30. Parapholyx klamathensis sinitsini, New Variety Plate 123, lig.^. 2-10 Shell similar to that of klamathensis but smaller, more globose; the shell thicker and more solid. Spire more elevated than in typical klamathensis; aperture rounder, not as effuse; columella callus heavier, more tightly ap- pressed to the columella. The umbilicus usually closed, rarely having a small chink. Color brownish horn, never greenish. Sculpture heavier than in klamathensis, growth lines more distinct, in a few specimens rib-like. In- terior of aperture reddish-brown. Lip bordered internally by a white margin which in old specimens forms a thickened callus. In contrast, klamathensis of typical variety has a thin lip without a callus. Columellar callus white. Whorls three. Some specimens with diagonal markings like pores. Aperture angulate below, as in klamathensis, but not markedly angular in some specimens. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 6.4 7.0 5.0 4.5 4.0 Holotype 5.6 7.1 4.4 4.3 4.3 Paratype 7.1 8.2 6.0 5.0 4.8 Paratype 5.6 6.8 4.5 4.0 3.6 Paratype 5.6 6.6 5.4 3.8 3.8 Paratype Type Locality. Bercley Spring, fourteen miles north of Klamath Falls, Oregon. Type Material. Five specimens, of which one is designated as holotype and the four others as paratypes, are deposited in the United States National Museum, Accession no. 531029. The holotype is shown on plate 123 as fig. 2; two paratypes on the same plate as figs. 3 and 4. A series of specimens from the same locality, collected by Mrs. L. Sinitsin, are accessioned in the United States National Museum, no. 531064. The indi- viduals of this last named series are designated as locotypes of the new variety. Parapholyx kla))iathensis sinitsini is a form smaller than the tyjucal klamathensis. The two forms have the same columella and angular base of aperture. The new variety has a higher spire than the typical form and the shell is more globose. Some individuals wdth diagonal ridges resemble diagonalis from Crater Lake but in that form the columella is wider, more concave and flatter and the aperture is more effuse. The spire of the new variety varies from flat to elevated depending upon the deflection of the aperture. Sinitsini has about the same size as Parapholyx solida optima but that form has a flat spire and a different aperture, especially in the region of the columella. This variety is named for Mrs. L. Sinitsin. Descriptions of Xew Species and A^eiv Varieties 229 Parapholyx pusilla. New Species Plate 117, fijis. 1-6 Shell small, with three whorls, scalariform, the second whorl standing on the body, turban-shaped; sutures distinct. Aperture roundly ovate, lips simple, lower lip rounded at base. Columella callus narrow, not expanded, separated from the columella region where it often projects leaving a dis- tinct umbilical chink. Aperture continuous by the presence of a parietal callus. Sculpture coarse, often costate. Shell Maximum Aperture Aperture Height Diameter Height Diameter 4.0 5.0 2.3 2.3 Holotvpe 4.5 4.3 2.5 2.1 Paratvpe 4.5 4.5 2.4 2.4 Paratvpe Type Locality. Six miles west of Pyramid Lake, Washoe County, Nevada. Type Material. One hundred twenty-five specimens taken from a Pleis- tocene deposit by Elbert Howard^ are deposited in the United States National Museum, Accession no. 308925. The individual from this lot chosen as holotype is shown on plate 117 as fig. 1. Figures 2 to 5 on the same plate are of paratypes. Parapholyx pusilla differs from Parapholyx rievadensis in that the new species has a more rounded shell, with elevated and turban-shaped second whorl and the lower portion of the aperture lacks the sharp angle caused by the columcllar callus in Jievadensis. The new species differs from P. solida in the form of the spire, aperture and base of lip. This is apparently an extinct sj^ecies. GENUS Planorhula Planorhula smithii. New Species Plate 118, figs. 11-12; plate 119, figs. 10-12 Shell resembling that of wheatleyi but larger, of five whorls, the spire whorls in the same plane and not so sunken toward the nucleus as in wheatleyi; no dorsal ridge as is developed in wheatleyi; umbilical opening wdth the whorls rounded, not flat sided and without the sharp carina dis- tinctive of wheatleyi. Crest behind aperture not as heavy or as thickened as in ivheatleyi. Sculpture of distinct spiral lines. Apertural lamellae as in armigcra not as in wheatleyi. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 3.0 7.1 5.5 2.0 1.3 Holotvpe 2.8 7.0 5.0 1.7 1.0 Paratvpe 2.9 6.9 5.8 1.5 1.0 Paratype Type Locality. Jackson County. Alabama. Type Material. Fifteen specimens, collected by H. H. Smith, are de- positee! in the United States National Museum, Accession no. 321196. The holotype is figured on plate 119. as fig. 10; jiaratyjies on the same plate as figs. 11 and 12. Externally Planorhula smithii resembles wheatleyi but the newly recog- nized species is readily distinguishable by the absence of the L-shaped 230 The Molluscan Fa7nily Planorhidae second labial lamella. Smithii is larger than crassilabris and has a much heavier lip callus. It somewhat resembles indianensis but lacks the axial height of that race and the latter also lacks the lip callus of smithii. Planorhula smithii is named for Herbert H. Smith. GENUS Menetus Menetus coloradoensis, New Species Plate 122, figs. 23-25 Shell acutely lenticular, flattened, with three whorls. Color blackish brown. A rounded carina on the periphery which is impressed both above and below the periphery a short distance from the edge. The carina is not acute (excepting in immature specimens) but is bluntly rounded. Upper surface flattened, with deeply inpressed sutures. The whorls tumid near the sutures. Base convex near the suture but flattened toward the periphery. Basal whorls separated by deep sutures. Sculpture ranging from coarse growth lines to evenly spaced ribs, spiral lines very fine. Some specimens begin with coarse growth lines and end with ribs. Aperture triangular, upper and lower lips arching downward and upward to meet the periphery which is not sharp but is narrowly rounded. Upper lip projects just above the periphery and is flat, but lower lip has a long columellar region and is convex. Aperture much wider than high, jmrplish within and somewhat pearly. Umbilicus rather wide and deep. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 1.0 1.6 Holotype 0.9 1.8 Paratype 0.9 1.5 Paratype Type Locality. Swamp at head of Eldora Lake, near Eldora, Colorado. Type Material. Deposited in the University of Colorado ALiseum, Ac- cession no. 10114. Holotype shown as fig. 25 on plate 122; two paratypes as figs. 23 and 24 on same plate. Menetus coloradoensis differs from eracuous in the pinched nature of the periphery, the swollen or tumid base near the suture, and the heavy (in some instances, costate) sculpture. Menetus exacuous megas has a pinched periphery, but in this variety the base and sculpture are as in typical exacuous. The new species is nearest to kansasensis but differs in having a more tumid base and a different type of rib-sculpture. Menetus cooper i crassilabris. New Variety Plate 121, figs. 19-21; plate 122, fig. 13; plate 123, fig. 26 Specimens like cooperi but with heavy callus just within lip. Shell of four whorls. Heavy spiral sculpture. Whorls usually rounded but with slight indication of carina at shoulder as in cooperi. Several spiral ridges below shoulder, and base often malleated as in cooperi. Umbilicus with rounded edges. Aperture rounded, not usually modified by carina. Most shells are smaller than cooperi. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 2.1 5.4 4.0 1.6 2.0 Holotype 1.1 4.0 3.6 1.0 4.6 4.0 1.0 4.1 3.6 Descriptions of New Species and New Varieties 231 Type Locality. Seattle, Washington. Type Material. Twenty-four specimens are in the United States Na- tional Museum bearing Accession no. 214590, one of which is selected as holotype and the remaining specimens become paratypes. Holotype is shown on plate 121 as fig. 20; and one paratype as fig. 19. Of the twenty-four specimens in the type lot all but one had a callus, this one being doubtfully referred to cooperi. The original labels of some lots in the National Museum carried identification as oregonensis. Evi- dently this was based upon the presence of a lip callus. However, cras- silabris lacks a peripheral carina and cannot be allied with oregonensis. Other collections have been determined as centervillensis, but the umbili- cus is distinctly different in crassilabris. Menetus cooperi crassilabris has been identified in collections from Colma, San Mateo County, California; Oakland, California; Portland, Oregon; Lake Washington at Seattle, Washington; and mountain swamps at Olga, W^ashington. The last named were erroneously identified as Menetus cooperi calioglyptus. One collection from Oakland was associated with typical cooperi. Menetus cooperi planospirus, New Variety Plate 122, figs. 3-6 Shell with three whorls, of yellowish horn color. Upper surface flat, the whorl bordered by a raised revolving ridge at the edge. Spire whorls sunken below general level. Base convex. Umbilicus deep, about one-fourth the diameter of the shell. Peripheral ridge stands out and elevated above the shell as a cord. Aperture modified by carina. Sculpture of rather coarse growth lines, crossed by heavy spiral lines. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 3.0 3.0 Holotype 2.6 3.0 Paratype 2.0 2.0 Paratype 2.2 2.4 Paratype Type Locality. Orcas Island, Puget Sound, Washington. Type Material. A collection of thirty-six specimens, taken by W. H. Souther, is deposited in the Museum of Comparative Zoology, Harvard University, Accession no. 31583. One of these, designated as holotype, is shown on plate 122 as fig. 5, and three paratypes are shown on the same plate as figs. 3, 4, and 6. Menetus cooperi planospirus is characterized by its very flat spire and the presence of a raised carina placed at the upper edge of the whorl. It differs from Menetus cooperi multilineatus in the position of the carina, and in having a flat rather than a convex spire. Menetus dalli. New Species Plate 140, figs. 22-24 Shell small, lenticular, with a bluntly angular periphery. Upper surface flatly convex, three whorls visible, sutures deeply incised. Lower sur- face flatly convex, the umbilical or spire region small, occupying one-sixth of the diameter of the shell. The lower surface is swollen over the umbili- 3.3 8.0 7.0 3.0 6. .5 5.6 2.6 5.9 5.0 2.5 5.9 5.0 .5 4.0 3.2 .4 3.2 2.7 2 2.9 2.2 232 The Molluscan Family Planorbidae cus. The lower surface has a somewhat pinched appearance, with an indistinct, impressed Hne bordering the periphery. Sculpture of coarse growth lines radiating from the periphery. At regular intervals there are larger rib-like projections, with four to six of the smaller ribs between. All the ribs extend into the spire cavity, which is deep. The sculpture is more conspicuous on the base of the shell. The umbilical (upper) side has the fine riblets more regularly spaced without the larger ones. This sculp- ture is most apparent on the large holotype specimen. There are likewise fine, impressed spiral lines. Aperture triangular, wider than high. Columella almost vertical. Lip thickened by callus, which includes the columellar and parietal walls. The right side of the aperture is acute and pinched. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 1.1 1.6 Holotvpe 1.0 1.5 Paratvpe 0.9 0.9 Paratype Type Locality. Caloosahatchie River, Florida. Type Material. Pliocene fossils, collected by W. H. Dall, deposited in the United States National Museum, Accession no. 112556. Holotype figured on plate 140 as Fig. 22; paratypes as figs. 23, 24. Menetus dalli differs from alabamensis in the former's smaller and deeper spire depression and its heavier growth lines forming riblets. It was identified by Dall (after whom the new species is named) as exacuous. It was associated with dilntatus and alabamensis aims. Menetus dilatatus floridensis, New Variety Plate 123, figs. 20-22 Shell small, of three whorls, slowly increasing in diameter. Color light horn. Body whorl forms a rounded obtuse angle as in dilatatus. Base flatly rounded. Spire depression wide, shallow, showing all of the whorls. Sculp- ture of fine growth lines crossed by fine spiral lines. Aperture rounded, not flaring. Outer lip thin. No callus on parietal wall. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 0.8 1.0 Holotype 0.7 0 . S Paratype 0.7 0.7 Paratype Type Locality. St. Johns River, Palatka, Florida. Type Material. Collected by W. H. Dall. Deposited in the United States National Museum, Accession no. 37585. Holotype shown on plate 123 as fig. 20; paratypes as figs. 21 and 22. Menetus dilatatus jioridensis differs from typical dilatatus in the fact that the new variety has a smaller aperture which is rounded, not flaring; has rounded body whorl, without trace of angulation; and has wider, shal- lower spire depression, showing all of the whorls. Menetus lahiatus. New Species Plate 121, figs. 9-11 Whorls three, rounded. Spire flattened, apex sunken. Base rounded, umbili- cus broad and shallow, one-sixth the diameter of the shell. Whorls and 0.9 2.5 2.1 0.8 2.3 2.0 O.S 2.0 1.6 1.0 2.6 2.1 0.9 2.3 2.0 1.1 3.1 2.6 1.2 3.0 2.3 Descriptions of N'ew Species and New Varieties 233 umbilicus rapidly increasing in diameter. Aperture ovately rounded, the lip with a heavy internal rim of callus which joins a distinct parietal callus, making the lip in some specimens continuous. Umbilicus varies in depth. Sculpture of fine growth lines, crossed by fine spiral lines, although the latter may be absent in some specimens. Shdl Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 0.5 0.5* Holotvpe 0.5 0.5 Paratype 0.6 0.5 Baker Coll., 2100 0.8 O.S Baker Coll., 2100 *A heavy callus redure.s the size (if the aperture. Type Locality. Terminal Island, Los Angeles County, California. Type Material. Three specimens, collected by Eastman, are in the United States National Museum, Accession no. 19002L Designated holotype and paratypes illustrated on plate 121 as figs. 11 and 9, 10, respectively. The type material was labelled as centervillensis. Taken in various southern California localities. Some large individuals of this species were collected from peat deposits by S. S. Berry, in Orange County, California. Two of these individuals, which have a heavy lip callus, are included as the third and fourth items in the above tabulation of shell characters (Baker Coll., no. 2100). Menetus labiatus differs from centervillensis in the shape of the um- bilicus and the aperture. Men&tus portlandensis, New Species Plate 121, figs. 12-18 Shell less elevated than in centervillensis, the body whorl depressed, rounded on the periphery, not angled as in centervillensis. Spire flat, three and one-half whorls, sutures impressed. Color blackish to light horn, usu- ally in the same shell. Base flatter than in centervillensis; the umbilicus wider, about one-fourth of the diameter of the shell. Aperture transversely ovate, wider than in c enter vUlensis and not as nearly round. Slight callus on parietal wall. Sculpture of coarsely impressed spiral lines, distinct in all specimens examined. Shell Greater Lesser Aperture Aperture Height Diameter Diameter Height Diameter 1.4 4.0 3.3 1.1 1.2 Holotype 1.3 3.5 3.0 0.8 1.0 Paratype 1.1 3.3 2.6 0.8 1.0 Paratype Type Locality, Tanner Creek, Portland, Oregon. Type Material. A large collection of one hundred shells, collected by J. E. Benedict, is deposited in the United States National Museum, Acces- sion no. 184182. The holotype is shown on plate 121 as fig. 12; six para- types on the same plate as figs. 13 to 18. The chief distinguishing characteristics of Menetus portlandensis are that the umbilicus is wider and shallower and the sjiiral lines on the shell are heavier than in other species of the genus. This new species has also been taken in the vicinity of San Francisco, California, and at Astoria, Oregon. In the latter instance it was associated with specimens of coopcri. ILLUSTRATIONS OF THE ANATOMY AND OF SHELLS ANATOMICAL SYMBOLS USED ON THE PLATES A, anus AG, abdominal ganglion AL, albumen gland AO, aorta AP, pulmonary vein ARM, anterior retractor muscles AU, auricle B, bulbous termination of verge BG, buccal ganglion BP, buccal pouch BR, buccal retractor muscle BS, blind sac or caeciun BY. blood vessel BW, body wall of gland C, canal CF, carrefour CG, cerebral ganglion CL, cilia CM, columella muscle CMC, cut portion of mantle collar and columella muscle CR. crop D, diaphragm DA, duct from albumen gland DC, duct of gland DG, duct of preputium DV, duct entering vergic sac E, eye EPI, epiphallus-like swelling EUD, external opening of vas deferens F, foot FL, fiagellum FO, female opening FOV, diverticula of ovotestis FPR, diverticula of prostate G, accessory gland GA, gland appendage GF, folds in wall of gland cavity GL, penial gland GX, ganglion GR, growth lines GW, wall of preputial sac GZ, gizzard H, head HT, heart IC, cavity of gland connecting with gland duct IN, intestine or space for intestine on surface of albumen gland J. jaw K, kidney L, lung LJ, lateral jaw LV, liver M, mantle MC, mantle collar MO. male opening MX, muscle of neck MP, muscular pads or pillars in preputium ( pilasters) MR, muscular ridge or diaphragm MS, suspensarv muscles of verge MT, mouth X^, nerve NA, section through neck NG, nidamental gland NS, new shell forming OC, outer cup of gland OD, oviduct OE, oesophagus OLV, opening of liver duct into stomach OT, ovotestis P, jiseudobranch PA, vergic appendage PC, pericardium PD, duct of prostate PF, prostate diverticula PG, pedal ganglia PL, pilasters PP, papilla in preputium PR, preputium PRM, posterior retractor muscle PRS, prostate PS, pneumostome PY, pyloris R, rectum RA, renal vein RD, ridge RK, ridge on kidney RL, radula RM, retractor muscle S, spermatheca SB, sarcobelum SC, sperm canal SD, spermathecal duct SG, salivary gland SCO, opening of sperm canal SJ, superior jaw SH, shell SK, saccular part of kidney SM, supporting muscle SO, ovisperm duct SP, spermatophore SPD, sperm duct ST, stylet STM, stomach SV, seminal vesicle T, tentacle TK, tubular part of kidney U, uterus UO, external opening of ureter UR, ureter V. verge VC, vergic sac VD, vas deferens VDV, vas deferens in vergic sac VF, folds in vergic sac VG, vagina VGL, visceral ganglion VL, velum VM, muscle to vergic sac VX, vein VO, opening between vergic sac and preputium VP, vergic papilla VS, vergic sac VT, ventricle X. canal in penial gland 238 The Molluscan Family Plauorbidae PLATE 1 Planorbis planorbis (Linn.) From a pond 25 miles southeast of Warsaw, Poland; from A. Jankowski. 1. Entire genital system spread out. The dark spaces are folds in the anatomical preparation. 2. Penial complex with muscles. 3. Head and foot showing form of pseudobranch. 4. Vertical section through penial complex to show small size of verge. 5. Section through verge and vas deferens. 6. Junction of oviduct and vas deferens to form ovisperm duct and connection with albumen gland and carrefour. 7. Section through prostate, oviduct, and vas deferens showing a prostate canal sepa- rated from the vas deferens. 8. Section through ovotestis. 9. Section through o\'otestis showing di\'erticula embedded in the liver cells. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 239 PLATE 1 240 The Molluscan Family Planorbidae PLATE 2 Segmentina and Hippeutis 1-6. Segmentina nitida (Miiller). From swamps on a meadow near Warsaw, Poland; from A. Jankowski. 1. Cross section of pilaster to which appendage is attached. 2. Vertical section of preputium showing position of gland-like appendage. 3. Upper view of cup of gland or appendage. 4. Vertical section of gland or appendage. 5. End of verge showing position of vergic appendage. 6. End of verge showing vergic appendage and outlet of sperm canal. 7-15. Hippeutis complanatus (Linn.). From pool in meadow in Jabtonna, 16 km. north of Warsaw, Poland; collected by A. Jankowski. 7. Two diverticula of ovotestis. 8. Cross section of prostate showing two canals, one for prostate (PD) and one for sperm duct (SPD). 9. Gland or appendage in preputium. 10. Outline of albumen gland (from above). 11. Upper part of vergic sac showing two flagella and the vas deferens. 12. Vertical section of penial complex showing relationship of verge, gland, or appendage, and flagella. 13. Head of animal showing form of pseudobranch and pneumostome. 14. Penial complex from the outside. 15. General dissection of genitalia omitting the penial complex. Line near figure indicates 1 mm. in length. Line at left of fig. 12 also indi- cates .size of figs. 3, 4, 5, 8, and 9. Figures 6 and 11 are greatly enlarged. Figure 14 has same magnification as fig. 15. Illustrations of the Anatomy and of Shells 241 VD FL PRS 242 The Molluscan Family Planorhidae PLATE 3 Segmentina and Bathyo))iphalus 1-4. Segmentina nitida (Miiller). From meadow near Warsaw, Poland; from A. Jan- kowski. 1. External view of penial complex. 2. Hermaphrodite complex. 3. Cross section of prostate and ducts of prostate and vas deferens. 4. Head showing position and form of pseudobranch. 5-10. Bathyomphalus contortus (Linn.). From Drewnica, a turfy ground 4 km. north- east of Warsaw, Poland; collected by A. Jankowski. 5. Head showing position and form of pseudobranch. 6. Pseudobranch showing position of rectum. 7. Cross section of ovotestis. 8. Cross section of prostate showing prostate duct sei)arate from sperm duct. 9. Penial complex from the outside. 10. Hermaphrodite complex dissected and spread out. Line near figure indicates 1 mm. in length. Line at left of fig. 7 also repre- sents size of figs. 3 and 8. Figure 9 is same magnification as fig. 10. Illustrations of the Anatomy and of Shells 243 PLATE 3 244 The Molluscan Family Plauorbidae PLATE 4 Pingiella peipinensis (Ping and Yen). New genus Peiping, China; from Fan Memorial Institute, Peiping, China. 1. Albumen gland showing position of stomach. 2. Portion of penial gland showing position of ducts. 3. Terminal end of penial gland, imder side. 4. Terminal end of penial gland, view from side showing internal canal. 5. Penial complex showing long duct of penial gland and long and peculiarly formed appendages. 6. Preputium cut open to show penial gland. 7. Preputium cut open to show penial gland and relationship of long duct. 8. Verge in vergic sac. 9. General dissection of genitalia, the organs separated and extended. Line near figure indicates 1 mm. in length. Figures 3 and 4 are greatly enlarged. lUustratioiis of the Anatomy and of Shells 245 246 The Molluscan Family Planorbidae PLATE 5 Pingiella and Polypylis 1,5. Pingiella peipinensis (Ping and Yen), new genus. Peiping, China. 1. Region of the pseudobranch. 5. Spermatheca of different shape. 2-4,6,7. Polypylis hemisphaerula (Benson). Peiping, China; from Fan Memorial Institute. 2. Outline of albumen gland. 3. Region of the pseudobranch. 4. Section through prostate and ducts. 6. Distal end of verge showing outlet of canal at the side. 7. Entire genitalia dissected and organs separated. Line near figure indicates 1 mm. in length. Figure 6 is greatly enlarged. Illustrations of the Anatomy and of Shells 247 PLATE 5 248 The Molluscan Family Planorbidae PLATE 6 Anisus vortex and Anisus spirorbis 1-4,6. Anisufi vortex (Linn.). From stream in meadow in Jabtonna. 18 km. north- east of Warsaw, Poland; collected by A. Jankowski. 1. Penial complex showing long and narrow vergic sac. 2. Stylet, drj' and somewhat crushed. 3. Section through prostate and sperm canal showing two ducts. 4. Section through upper portion or preputium and vergic sac, showing papiUa in preputium, stylet and outlet of sperm canal at the side of the verge. 6. Pseudobranch showing relationship to rectum. 5,7-13. Aiiisus spirorbis (Linn.). From a trench in Struga, 12 km. northeast of War- saw, Poland; collected by A. Jankowski. 5. St5det at end of verge with outlet of sperm canal at side of verge. 7. Two diverticula of ovotestis. 8. Cross section through prostate and o\ iduct. 9. Albumen gland, upper part. 10. Penial complex in vertical section showing stylet, muscular i)apilla, and jiilasters. 11. Foot, pseudobranch, and jmeumostome. 12. Entire genitalia dissected and separated. 13. Penial complex of specimen with vergic sac shortened and club-shaped. Line near figure indicates 1 mm. in length. Figures 2 and 5 are greatly enlarged. Illustrations of the Anatomy aiid of Shells 249 PLATE 6 250 The Molluscan Family Planorbidae PLATE 7 Anisus leucostomus and Ainsus septemgyratus 1-5. Anisus leucostomus (Millet). From small pond in Bielany Park, Warsaw. Poland; collected by A. Jankowski. 1. Foot, pseudobranch, and pneumostome. 2. Genitalia dissected and the organs separated. Figure under seminal vesicle shows this organ stretched out. 3. Muscular ring or diaphragm in upper part of preputiimi showing papilla with stylet protruding. 4. End of oviduct and vas deferens showing where ovisperm duct joins the ovi- duct and vas deferens. 5. Stylet. 6. Anisus septemgyratus (Ziegler). From turfy meadow in Drewnica, 4 km. northwest of Warsaw, Poland; collected by A. Jankowski. 6. Outline of genitalia exclusive of the penial complex. Line near figure indicates 1 mm. in length. Line at left of fig. 5 is only for .size of figs. 3 and 4. Illustrations of the Anatomy and of Shells 251 PLATE 7 252 The Molluscan Family Planorbidae PLATE 8 Intha and Polypylis 1-8,11. Intha capitis Annandale. From Inle Lake, South Shan State, Burma, India; collected by Dr. N. Annandale. 1. Outline of albumen gland. 2. Pseudobranch and rectum. 3. Head of animal showing tentacles and eyes. 4. Distal end of verge. 5. A spermatophore. 6. Penial complex, dorsal view. 7. Cross section of penial gland. 8. Vertical section of penial complex showing verge, gland, and duct. 11. ^'entral view of entire genitalia, showing the large size of the fiagella. 9,10. Polypylis hemisphacnda (Benson). Peiping, China; from Fan Memorial In- stitute. 9. Section of penial complex cut open to show verge, diaphragm and pilasters. 10. Penial complex, ventral view. Small figure at right shows insertion of vas deferens at junction of vergic sac and flagellum. Dorsal view. Line near figure indicates 1 mm. in length. Figures 1, 5, 6. and 7 have same magnification as fig. 11. Figure 4 is greatly enlarged. Illustrations of the Anatomy and of Shells 253 254 The Molluscan Family Planorbidae PLATE 9 Drepanotrema and Australorbis 1-3. Drepanotrema anatinitm (Orbigny). From Viejo, Puerto Rico; from Dr. W. A. Hoffman. 1. Penial complex showing form of flagellum. 2. Genitalia dissected and organs separated. Note the small number of ijrostate diverticula. 3. Head and foot showing form of pseudobranch. 4-10. Australorbis globratus (Say). From Lares, Puerto Rico; from Dr. W. A. Hoff- man. 4. Cross section of portion of ovotestis to show multiple branched diverticula. 5. Distal end of verge showing opening at center. 6. One diverticulum of prostate showing multiple branching at end. 7. Pseudobranch and pneumostome. 8. Outline of albumen gland showing depression occupied by intestine. 9. Section of penial complex showing long and narrow verge and vergic sac. 10. Entire genitalia dissected and organs separated. Note branched form of pros- tate diverticula and multiple nature of ovotestis diverticula. Line near figure indicates 1 mm. in length. Line near left of fig. 1 is also for fig. 3. Illustrations of the Atiatomy cuid of Shells 255 PLATE 9 256 The Molluscan Family Planorbidae PLATE 10 Drepanotrema hoffmani F. C. Baker From Isabela, Puerto Rico; collected by Dr. W. A. Hoffman. 1. Animal removed from shell showing pigmentation of mantle, shape of head and tentacles, and position of stomach (STM) in body. 2. Genitalia dissected and organs separated. 3. Fore part of body showing head, pseudobranch, etc. 4. Albumen gland showing attachment of ducts. 5. Penial complex showing attachment of short flagellum, vas deferens, etc. 6. Section of penial complex showing verge, pilasters, vas deferens, flagellum, etc. 7. Upper part of penial complex showing relationship of flagellum, vas deferens, vergic sac, retractor muscle, etc. 8. Penial complex of another specimen. 9. Distal end of verge showing central outlet of sperm canal. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 257 PLATE 10 258 The Molluscan Family Planorbidae PLATE 11 Drepanotrema lucidum (Pfciffer) From Havana, Cuba; collected by Dr. C. G. Aguayo. 1. Head and foot with prepiitium and verge extended from male genital opening. The pseudobranch and rectum are also shown. 2. Head and foot with only preputinm extended from male genital opening. 3. Genital system dissected and organs separated. 4. Penial complex showing flagellum, vas deferens, etc. 5. Penial complex with very long flagellum. 6. Diagram of penial complex showing preputium and \crge extended from male genital opening. 7. Relationship of vas deferens, flagellum, retractor muscle in body of animal in specimen with preputium and verge extended from male opening. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 259 PLATE 11 260 The Molhiscan Family Plauorhidae PLATE 12 Tropicorbis havanensis (Pfeiffer) From Xew Orleans, La.; collected by Dr. E. Carroll Faust. 1. Penial complex in section to show verge and pilasters in vergic sac. 2. Muscular ring or ridge between vergic sac and preputium (diaphragm). 3. Distal end of verge showing central opening of sperm canal. 4. Body of snail showing pseudobranch, pneumostome, rectum, and frilled ridge or crest over rectum. 5. Body of snail showing pigmentation of mantle. 6. Albumen gland from above. 7. Portion of genitalia at junction of oviduct and sperm duct with ovisperm duct. Also entrance of albumen duct into carrefour and thence to oviduct. From below. 8. Same as fig. 7, from above. 9. Single diverticulum of prostate showing canal distinct from that of sperm duct. 10. Penial complex showing enlargement of preputial sac. 11. Genitalia dissected and the organs separated, showing relationship of all organs. Line near figure indicates 1 mm. in length. Lme at left of fig. 1 is also for figs. 7, 8, and 9. Line at left of fig. 11 is also size for fig. 6. Illustrations of the Anatomy and of Shells 261 PRS PLATE 12 262 The Molluscan Family Planorhidae PLATE 13 Tropicorbis 1-3. Tropicorbis obstructus (Morelet). From New Orleans, La.; collected by Dr. E. C. Faust. 1. Genitalia dissected and organs separated. 2. Cross section of ovotestis in non-gravid stage. 3. Cross section of ovotestis in gravid stage with ova in diverticula. Line at right indicates 0.5 mm. in length. 4-10. Tropicorbis riisci (Dunker). From Lares, Puerto Rico; from Dr. W. A. Hoffman. 4,5. Cross sections of prostate diverticula showing bending at end. Also presence of prostate duct distinct from sperm duct. 6. Penial complex, external view\ 7. Albumen gland from below showing duct (DA). 8. Vas deferens showing branching to form sperm duct and prostate duct (greatly enlarged) . 9. Portion of genitalia dissected and organs separated. Organs as in fig. 1. 10. Head of animal showing pseudobranch and imeumostome as well as ridge over rectum. Line near figure indicates 1 mm. in length. Line at left of figs. 4 and 5 is for both figures. Illustrations of the Anatomy and of Shells 263 PRS PLATE 13 264 The Molluscan Family Plauorbidae PLATE 14 Gyraulus albus (Miiller) From pond in Krolikania, a suburb of Warsaw, Poland; from A. Jankowski. 1. Penial complex sectioned to show verge, stylet, etc. 2. Penial complex, external view. 3. Fore part of animal showing pseudobranch and pneumostome. 4. Fore part of animal showing pseudobranch, pneumostome, and venation of some of these organs. 5. Albumen gland from below. 6. Portion of genitalia showing attachments of albumen gland duct, oviduct, sperm duct, and general relationship of these and other organs. 7. Genitalia dissected and organs separated. 8. Stylet at end of verge with sperm canal outlet at side of verge. 9. Section of prostate showing distinct canals for prostate and sperm duct. Three diverticula are shown. 10. Section through ovotestis near front end. 11. Distal end of ovotestis showing grouping of diverticula. Line near figure indicates 1 mm. in length. Line at lower right corner of plate is for figs. 5, 6, 7. 9, 10, and 11. Figure 8 line is one-sixth of 1 mm. in length. Illustrations of the Anatomy and of Shells 265 PLATE 14 266 The Molluscan Family Planorbidae PLATE 15 Gyraulus 1-7. Gyraulus hirsutus (Gould). From Bass Creek, Lake Nipissing, Ontario, Canada; received from A. LaRocqiie. 1. Genitalia dissected and organs separated. A portion of the intestine is shown beneath the albumen gland. 2. Penial complex, external view. 3. Fore end of body showing pseudobranch, pneumostome, rectum, etc. 4. Distal end of genitalia showing connection of various ducts. From right side. 5. Same as fig. 4, from left side. 6. A single diverticuhun of the prostate with duct separate from the sperm duct. 7. Two diverticula of the ovotestis. 8-10. Gyraulus vcrmicularis (Gould). From Stone Lake, Golden Gate Park, San Francisco, California; from Dr. G. D. Hanna. 8. Fore end of body showing pseudobranch. 9. Distal end of genitalia showing relationship of ducts. 10. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length. Line in upper left corner of plate is for figs. 4, 5, 6, and 7. Illustrations of the Anatomy and of Shells 267 PLATE 15 268 The Molluscan Family Planorhidae PLATE 16 Gyraulus deflectus obliquus (DeKay) From Taylor Lake, Masham, Quebec, Canada; collected by A. LaRocque. L Penial complex in vertical section. 2. Penial complex of specimen with bulbous termination of vergic sac. 3. External view of penial complex showing relationship of parts. Also male opening behind tentacle. 4. Genitalia dissected and organs separated. 5. Section through portion of penial complex at junction of vergic sac and preputial sac to show thickened portion with papilla. 6. Stylet. Distal end of verge shows sperm canal outlet at side. 7. Terminal diverticula of ovotestis, showing de\-eloping ova. 8. Terminal diverticula of ovotestis from left side. 9. Section through diverticula of ovotestis. 10. Distal end of genitalia showing position of sperm duct, oviduct, albumen duct, etc. 11. Section of prostate near middle. 12. Section of prostate six diverticula from front end. 13. Body and foot of animal showing pseudobranch, etc. 14. Pseudobranch showing network of blood vessels. 15. Another form of pseudobranch. Line near figure indicates 1 mm. in length. Line at middle left of i)late indicates size of figs. 5, 6. 7, 8, 9, 11, and 12. IllustrdtioDS of the Anatomy and of Shells 269 11 12 PLATE 16 270 The MoUuscan Family Planorbidae PLATE 17 Gyraulus 1-5. Gyraulus circumstriatus (Tryon). From Wainwright Park, near Mott Lake, Alberta, Canada; collected by Dr. Swales. 1. Genitalia dissected and organs separated. Outline. Penial complex in natural position. 2. Distal end of genitalia showing duct connections. From left side. 3. Pseudobranch and pneiunostome. 4. Animal removed from shell showing position of several organs. 5. Two diverticula of ovotestis in gravid condition. 6-12. Gyraulus parvus (Say). From Winnebago Lake, near Oshkosh, Wisconsin; col- lected by F. C. Baker. 6. Genitalia dissected and organs separated. 7. Distal end of genitalia, from left side. 8. Portion of fore end of animal showing pseudobranch, etc. 9. Albumen gland showing attachment of oviduct. 10. Three di^'erticula of prostate with prostate duct below and sperm duct at the side. 11. Two diverticula of ovotestis. 12. Penial complex opened to show verge, stylet, papilla, etc. Line near figure indicates 1 mm. in length. Figures 5, 10, and 11 have same magnification as fig. 12. Illustratious of the Anatomy and of Shells 271 272 The Molluscan Family Planorbidae PLATE 18 Gyraulus and Arniiger 1-5. Gyrauhis similaris (F. C. Baker). From Smartweed Lake, near Tolland, Colorado; collected by Dr. Frank Smith. 1. Genitalia dissected and organs separated. 2. Distal end of genitalia showing arrangement of durt.'<. 3. Penial complex in section showing verge, stylet, and preputium. 4. Stjdet. Outlet of sperm canal is shown at side of verge. 5. Head and foot of animal showing pseiidobranch. 6-11. Armiger crista (Linn.). From pond in Krolikarnia, a suburb of Warsaw, Poland; collected by A. Jankowski. 6. Head showing form of pseudobranch. 7. Genitalia dissected and organs separated. 8. Albumen gland from side. 9. Penial complex in .section showing verge without stylet. 10. End of verge showing absence of stylet and jjresence of a fleshy papilla. Sperm canal with outlet in center of verge. 11. End of verge from side showing relationship of jiapilla and canal. Line near figure usually indicates 1 mm. in length. Line at left of fig. 4 measures one-fifth of 1 mm. Line in center of fig. 7 is also for fig. 8. Same line equals 0.5 mm. for fig. 9. Figures 10 and 11 are much enlarged. Illustrations of the Anatomy and of Shells 273 274 The Molluscan Family Planorbidae PLATE 19 Gyi'aulus 1-3. Gyraidus co7ivexiusculus (Hutton). From Calcutta, India; from Dr. B. Prashad. 1. Cross section of one diverticulum of prostate showing separate canals for prostate duct and sperm duct. 2. Genitalia dissected and organs separated. 3. Pseudobranch and pneumostome. 4-9. Gyraulus latestomus F. C. Baker. From Cedar Lake, Algonquin Park, Ontario, Canada; collected by A. LaRocque. 4. Distal end of genitalia from left side. 5. Albumen gland from below, showing loop of intestine. 6. Penial complex. 7. Cross section of one diverticulum of prostate. 8. Anterior end of body showing pseudobranch and ])neumostome. 9. Genitalia dissected and the organs separated. Line near figure indicates 1 mm. in length. Figures 1 and 7 are greatly enlarged. Illustratioihs of the Anatomij and of Shells 275 PLATE 19 276 The MoUuscan Family Planorhidae PLATE 20 Planorbarius corneus (Linn.)- From branch of Wista River at Morysinek, 5 km. .south of Warsaw, Pohuid; collected by A. Jankovvski. 1. Penial gland and appendages in extended position. 2. Section through appendage at C in fig. 1. 3. One diverticulum of ovotestis with ripe ovum (greatly enlarged). 4. Cro.ss section through prostate, uterus, and nidamental gland. 5. Cross section of ovotestis in gravid specimen. 6. Vergic sac opened to show verge and canal in gland. 7. Retractor muscles in tyjjical specimen. 8. End of verge showing i)enial appendage. 9. Albumen gland. 10. Portion of head .showing jiseudobranch, pneumcstome, and rectum with ridge. 11. Penial complex opened to show position of jienial gland, verge, pilasters, etc. Penial appendage is retracted. 12. Penial complex from outside showing muscles. 13. Genitalia dissected and organs separated, showing particularly the form of jirostate and its junction with the vas deferens and sperm duct. Line near figure indicates 1 nmi. in length. Line at right of fig. 1 is also for fig. 2. Line at left of fig. 6 represents 0.5 mm. in length. lUustratioihs of the Auatouiy and of Shells NG 277 278 The Molluscan Family Planorbidae PLATE 21 Indoplanorbis exustus (Deshayes) From Hsipaw, North Shan State, Burma, India; collected by Dr. B. N. Chopra and Dr. H. S. Rao; contributed by Dr. B. Prashad. 1. Pcnial complex in natural position. 2. Fore part of animal showing pseudobranch and pneumostome, with preputium protruded from male opening and lying on the neck of the animal. 3. Genitalia dissected and organs separated. 4. Pleated pseudobranch and pneumostome. 5. Under side of preputium everted through male opening in the neck of the animal. 6. Pseudobranch from side showing branched or pleated condition. 7. Cross section of ovotestis showing se\'eral gra\id diverticula. 8. Cross section of prostate. 9. Two diverticula of prostate. 10. Portion of prostate showing relationship of vas deferens, sperm duct, and diver- ticula of gland. Line near figure indicates 1 mm. in length. Figures 9 and 10 are greatly magnified. Figures 1, 2, 3, and 10 were published in Jour. Mori)h., LV, plates 1 and 2. Illustrations of the Anatomy and of Shells 279 PLATE 21 280 The Molluscan Family Plauorbidae PLATE 22 Indoplanorbis and Helisoma 5-9. Indoplanorbis exustus (Deshayes). Continued from plate 21. 5. Retractor muscle of verge showing branching to vergic sac. Also nerve connection. 6. Cross section of preputium in extended condition as .-^hown in fig. 7. 7. Penial complex of specimen in breeding condition with preputium extended from male opening in neck. Compare with fig. 1 on plate 21. 8. Section of vergic sac through bulbous termination of verge. 9. Section of vergic sac through verge. Line near figure indicates 1 mm. in length. Figure 5 is enlarged. Figure 6 has same magnification as fig. 7. These figures were published in Jour. Morph. 1. Helisoma anccps latchfordi (Pilsbry). 1. Verge. Also enlarged portion of vas deferens (epiphallus). 2-4,11. Helisoma anccps pcrcarinatiDii (Walker). 2-4. A'ariation in form of muscles and in position of verge in preputium. Greatly enlarged. 11. Penial gland with cup turned back to show folds in inner cup. 10, 12. Helisoma anccps (Menke). 10. End of verge .showing papilla and sperm canal outlet. 12. Prostate showing attachment of prostate duct to sperm duct. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 281 282 The Molluscan Faintly Planorbidae PLATE 23 Helisoma anceps (Menke) 1-4,7-11. Helisoma anceps (Menke). From Gillespies Pond, Collinsville, Connecticut; collected bj^ F. C. Baker and Leslie Brewer. 1. Cross section of penial gland showing cup, folds, and duct. 2. Section of penial complex to show position of gland in preputium. 3. Exterior view of penial complex showing short duct on outside of preputium. 4. Region of the neck showing pseudobranch, pneumostome, and rectum. 7. Albumen gland from below. 8. Penial complex of specimen in which gland in preputium has been pushed upward. 9. Cross section of prostate showing multiple form of diverticula. 10. Cross section of ovotestis. 11. Genitalia dissected and organs separated. 5,6. Helisoma anceps latchfordi (Pilsbry). From Meach Lake, Quebec, Canada; col- lected by A. LaRocque. 5. Diaphragm in preputial sac view from below. 6. Section through diaphragm showing entrance of gland duct into vergic sac cavity just above diaphragm. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 283 ~PRS PLATE 23 284 The Molluscan Family Planorbidae PLATE 24 Helisoma trivolvis (Say) Collected from Oneida Lake, New York, by F. C. Baker, except where otherwise stated. L Penial complex. Specimen with portion of preputium containing gland pushed upward. Pool near Green Lake, Wisconsin. 2. Penial complex in vertical section. Specimen with preputium pushed upward. Illinois River, near Peoria, Illinois. 3. Penial complex. Young specimen with 3Vi> whorls. Devils Lake, Wisconsin. 4. Section through penial gland showing folds in cup. 5. Penial complex in immature specimen. Pond near Sturgeon Bay, Wisconsin. 6. Side view of albumen gland. 7. Albumen gland from below. 8. Section through penial gland in specimen in normal, non-breeding condition. 9. Section through ovotestis near anterior end. 10. Section through penial complex in region of diaphragm. IL External view of penial complex showing duct uncoiled and stretched out, indi- cating great length. 12. Region of neck showing pseudobranch, pncumostome, rectum, etc. 13. Section through prostate and uterus near middle of gland. 14. Penial gland somewhat contracted at cup end. 15. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 285 PLATE 24 286 The Molluscan Family Planorbidae PLATE 25 Helisoma pilsbryi (F. C. Baker) 1-7. Helisoma pilsbryi (F. C. Baker). From Chetek Lake, Barron County, Wisconsin; collected by F. C. Baker. 1. Penial complex with vergic sac drawn to side of preputium. 2. Cross section of penial gland. 3. Pseudobranch and pneumostome. 4. Outline of genitalia with organs separated. 5. Penial complex from outside, in normal position. 6. Penial comjilex of specimen with preimtium pushed upward. 7. Penial complex showing great length of penial gland duct. 8-13. Helisoma pilsbryi injracarinatum F. C. Baker. Unless otherwise stated specimens are from Basswood River Rapids, Ontario, Canada; collected by A. R. Cahn. 8. Penial complex of specimen with large preputium. From Rideau River Rapids, Ottawa, Canada; collected by A. LaRocque. 9. Penial complex with preputium pushed upward, showing length of penial gland duct. 10. Penial complex of immature specimen. From Bamiji Lake, Ontario, Canada; collected by Dr. A. R. Cahn. 11. Pseudobranch and adjacent organs. 12. Section through prostate and uterus. 13. Outline of genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustrations oj the Anatomy and of Shells 287 PLATE 25 288 The Molluscan Family Planorhidae PLATE 26 Helisoma 1-5. Helisoma horni (Tiyon). From Paul Lake, British Columbia; collected by Prof. D. S. Rawson. 1. Penial complex in breeding condition, the preputium pushed upward. 2. Outline of penial gland. 3. Outline of genitalia dissected and organs separated. 4. Cross section through oviduct, sperm duct, and nidamental gland. 5. Cross section through prostate and o\iduct, near middle of gland. 6-13. Helisoma iruncatum (Miles). From Winnebago Lake, near Oshkosh, Wisconsin; collected by F. C. Baker. 6. Penial complex with penial gland duct in normal position coiled on surface of preputium. 7. Penial complex with penial gland duct pulled out to show great length. 8. Cross section of ovotestis near anterior end. 9. Cross section of penial gland. 10. Cross section of prostate and oviduct near anterior end. 11. Head showing position of pseudobranch, pneumostome, and rectum. 12. Penial complex with penial gland duct spread out. Preputium is partly pushed upward. 13. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 289 PLATE 26 290 The Molluscan Family Planorbidae PLATE 27 Helisoma campamdatum (Say) From Oneida Lake, New York, near Brewerton; collected by F. C. Baker. 1. Section through penial gland. 2. Albumen gland from below. 3. Section through diaphragm showing relationship of penial gland duct to vergic sac. 4. Section through ovotestis near anterior end. 5-7. Penial complex of Helisoma campayiulatum sniithi (F. C. Baker), from Douglas Lake, Michigan, showing variation in form, especially the preputium. -14. Helisoma campaiudatinn canadense F. C. Baker. From Sturgeon Lake, Ontario, Canada; collected by Dr. A. R. Cahn. 8. Penial complex. 9. Penial complex showing penial gland duct coiled between preputium and vergic sac. Also variation in muscles. 10. Section of penial complex showing relationship of penial gland to verge. 11. Penial complex with penial gland duct uncoiled to show length. 12. Section through prostate near middle of gland. 13. Pseudobranch, pneumostome, and rectum. 14. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustrations oj the Anatomy and oj Shells 291 PLATE 27 292 The MoUuscan Family Plauorhidae PLATE 28 Helisoma 1-5. Helisoma oregoncnse (Tryon). From Tooele Co., Utah; collected by J. Hen- derson. 1. Penial complex showing long penial gland duct. 2. Genitalia dissected and organs separated. 3. Cross section of prostate near middle of gland. 4. Penial gland viewed from above. 5. Section through penial gland. 6-14. Helisoma scalare (Jaj'). From Lake Butler, Florida; received from Dr. E. A. Andrews. 6. Entrance of penial gland duct into vergic sac. 7. Section through penial gland. 8. Pseudobranch and pneumostome. 9. Penial complex with preputium pushed upward. 10. Penial complex in normal position, the penial gland duct extended. 11. Penial complex in section to show relationship of organs. 12. Section through prostate near middle. 13. Section through ovotestis near anterior end. 14. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustratio))s of the Anatomy and of Shells 293 PLATE 28 294 The MoUuscan Family Planorbidae PLATE 29 Helisoma 1-6. Helisoma trivolvis pseudotrivoivis (F. C. Baker) ^ lentum Say. From St. Joseph, Champaign Co., Illinois; collected by F. C. Baker. 1. Penial complex with penial gland duct spread out to show length. 2. Penial complex in section showing penial gland m natural position in pre- putium. 3. Penial complex with penial gland duct coiled on preputium. 4. Penial gland in section. 5. Penial complex in section showing preputium pushed upward and penial gland duct vmcoiled. From Illinois River, Peoria, Illinois. 6. Neck of animal showing penial gland everted. From Reelfoot Lake, Tennessee. 7-13. Helisoma trivolvis lentum (Say). From Xew Orleans, Louisiana; collected by E. C. Faust. 7. Penial complex with penial gland everted. 8. Penial complex with penial gland duct uncoiled. 9. Verge fully extended with sections in two places as indicated. 10. End of verge showing exit of sperm canal with small, lip-like processes sur- rounding the opening. 11. Head and neck of animal showing penial gland and verge everted. 12. Penial complex with penial gland and verge everted. 13. Verge in fig. 12 removed from penial complex. 14-16. Helisoma trivolvis macrostomum (Whiteaves). 14. Penial complex. From Bayfield, Wisconsin; collected by F. C. Baker. 15. Penial complex with preputium pushed upward. Same locality as fig. 14. 16. Penial complex with penial gland duct uncoiled. From Lake Gauvreau, Canada; collected by A. LaRocque. 17,18. Helisoma trivolvis fallax (Haldeman). From Cambridge, Massachusetts; col- lected by W. J. Clench. 17. Penial complex showing large size of preputium. 18. Exterior view of penial gland. 19-22. Helisoma chautauquense F. C. Baker. From Chautauqua Lake, New York; collected by F. C. Baker. 19. Penial complex of immature specimen. 20. Exterior view of penial gland. 21. Verge much retracted. 22. Penial complex of adult .specimen in normal condition. Line near figure indicates 1 mm. in length. In fig. 10 line equals 0.5 mm. Illustrations of the Anatomy and of Shells 295 296 The Molluscan Family Planorbidae PLATE 30 Helisonia 1-9. Helisoma plcxatum (Ingersoll). Collected by J. Henderson. 1. Penial complex with penial gland duct uncoiled. From Columbine Lake, Colorado. 2. Penial complex with vergic sac cut open to show form of verge. 3. Penial comiilex in section to show form of gland. From Columbine Lake, Colorado. 4. Genitalia dissected and organs separated. From Smartweed Lake, Colorado. 5. Cross section of penial gland. From Lower Los Lagos, near Smartweed Lake. 6-8. Section of vergic sac showing form of \erge in different individuals. From Teton River, north of Rexburg, Idaho. 9. Form of verge in a specimen from Smartweed Lake, Colorado. 10-19. Helisoma subcrcnalum (P. P. Carpenter). From one mile west of Devon, Montana; collected by J. Henderson. 10. Penial complex showing short penial gland duct in immature specimen. 11. Section of penial gland. 12. Cross section of prostate about midway of its length. 13. Section through penial complex showing verge and penial gland. 14. Albumen gland from below. 15. Genitalia dissected and organs separated. 16. Head showing pseudobranch, pneumostome, and rectum. 17. Penial complex with penial gland duct uncoiled. 18. Penial complex in section showing form of penial gland and verge. 19. Penial complex with vergic sac cut open to show verge. Figures 17-19 are from specimens collected at Cottonwood Pass, near Gypsum, Colorado. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 297 298 The Molluscan Family Planorbidae PLATE 31 Helisoyna 1-7. Helisoma corpulent lun (Say). From Knife Lake, Minne.?ota and Lake La Croix, Ontario; collected by Dr. A. R. Cahn. 1. Cross section of ovotestis. From Knife Lake. 2. Cross section of prostate and uterus at X in fi^. 3. From Knife Lake. 3. Genitalia dissected and organs separated. From Knife Lake. 4. Penial complex with preputium pushed upward and penial gland duct imcoiled. 5. Penial complex and penial gland duct in natural position. From Knife Lake. 6. Penial complex of immature specimen, shell 12 nun. in diameter. From Lake La Croix. 7. Penial complex of specimen with shell 14 mm. in diameter. From Lake La Croix. 8-13. Helisoma corpulentinn multicostotum F. C. Baker. From Kahnipiminanicock Lake, Ontario, Canada; collected by Dr. A. R. Cahn. 8. Cross section of penial gland. Duct not shown. 9. Penial complex of immature specimen, shell 5.5 mm. in diameter. Duct short. 10. Penial comjilex of half-grown animal, shell 14.5 mm. in diameter. 11. Penial complex of another half-grown specimen, shell 14.5 mm. in diameter. 12. Penial complex of specimen almost adult, shell 16 mm. in diameter. 13. Penial complex of adult animal, shell 23 mm. in diameter. Duct long, uncoiled. 14-18. Helisoma corpulentum vermilionense F. C. Baker. From Lake Vermilion, Min- nesota; collected by F. C. Baker. 14. Penial complex showing preputium pushed upward. Duct imcoiled. 15. Section of penial gland showing cup and penial gland duct. 16. Penial complex, specimen about one-fourth grown. 17. Penial complex in specimen somewhat older than fig. 16. 18. Penial complex of animal about half-grown. Verge of different shape. 19. Helisoma whiteavesi F. C. Baker. From Mille Lacs, Ontario, Canada; collected by A. R. Cahn. 19. Penial complex with small vergic sac, the penial gland duct uncoiled. 20-22. Helisoma magnificiun (Pilsbry). From Greenfield Pond, 1 mile south of Wil- mington, North Carolina; collected by Dr. Paul Bartsch. 20. Penial complex with penial gland duct uncoiled. 21. Penial complex in section. 22. Penial gland in section. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 299 PLATE 31 300 The Molluscan Family Planorbidae PLATE 32 Helisoma 1-7. Helisoma tenue californiense F. C. Baker. From pools from artesian wells, near Shandon, California; collected by Dr. G. D. Hanna. 1. Genitalia dissected and organs separated. 2. Penial complex cut open to show verge. 3. Penial complex with vergic sac at summit of preputium. 4. Pseudobranch, pneumostome, and rectum. 5. Penial gland viewed from the outside. 6. Section of prostate and uterus. 7. Penial complex with penial gland duct uncoiled. From Prospect Park, Red- lands, California; collected by Dr. S. S. Berry. 8. Helisoma subcrenatum (P. P. Carpenter). Variety. From Pass Lake, Fidalgo Island, Puget Sound, Washington; collected by J. Henderson. 8. Penial complex with preiiutium pushed upward. 9,10. Helisoma occiclentale (Cooper). From Wacos Bay, Klamath Lake, Oregon; collected by J. Hendenson. 9. Position of verge in vergic sac. 10. Penial complex with preputium pushed ujjward. 11-17. Helisoma traskii (Lea). From slough near Kern River, three miles northeast of Bakersfield, California; collected by L. G. Ingles. 11. Penial complex cut open to show form of penial gland. 12. Cross section through prostate, uterus, and nidamental gland. 13. Section through penial gland. 14. Penial complex in normal position with penial sland duct uncoiled. 15. Pseudobranch, pneumostome, and rectum. 16. Bifid tentacle. 17. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 301 PLATE 32 302 The Molluscan Family Planorhidae PLATE 33 Helisoma 1-7. Helisoma duryi eiidiscus Pilsbiy. From Silver Springs, Florida; collected by T. Van Hyning. 1. Penial complex showing swollen duct of penial gland and position of verge in vergic sac. 2. Penial complex from exterior with penial gland duct uncoiled. 3. Penial gland in section showing the long, shallow cup. 4. Exterior view of penial gland. 5. Penial complex with preputium pushed upward. 6. Penial complex of immature specimen, shell 6.5 mm. in diameter. 7. A very wide example of penial complex. 8-10, 12, 16-19. Helisoma duryi normale Pilsbry. 8. Penial complex. From near Paines Prairie, Gainesville, Florida; collected by T. Van Hyning. 9. Penial complex with swollen preputium. From Santa Fe River, High Springs, Alachua Co., Florida; collected by T. Van Hyning. 10. Penial gland in section. Same locality as fig. 9. 12. Penial complex. Variation in form. From Tamiami Trail, 40 miles west of Miami, Florida; collected by W. F. Shay. 16. Head and neck with penial gland protruding from male opening. Same locality as fig. 12. 17. Penial complex. A normal form showing short penial gland duct. Same locality as fig. 12. 18. Penial complex. A very wide example. Same locality as fig. 12. 19. Penial gland of half-grown specimen. From near Gainesville, Florida. 11,13,14. Helisoma duryi (Wetherby), near typical form. Same locality as fig. 12. 11. Penial gland, partly contracted. 13. Penial complex with penial gland protruding from male opening. 14. Penial complex of normal specimen. 15. Helisoma duryi normale Pilsbry, varying toward intercalare (Pilsbry). 15. Genitalia dissected and organs separated. From canal at Boynton, Florida; collected by W. F. Shay. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 303 304 The Molluscan Family Planorbidae PLATE 34 Carinifex ponsonbyi E. A. Smith From Upper Klamath Lake, Oregon; collected by J. Henderson. 1. Head and foot showing pseudobranch and pneumostome. 2. Penial complex showing muscle system and short penial gland duct. 3. Penial complex cut open to show verge and penial gland. 4. Genitalia dissected and organs separated. Shows unusual position of spermatheca. 5. Albumen gland from below. 6. Portion of genitalia showing relationship of oviduct, sperm duct, ovisperm duct. and duct to albumen gland. 7. Cross section of prostate and uterus. 8. Cross section of prostate near distal end. 9. Cross section of ovotestis near proximal end. 10. Section through penial gland to show duct and folds. IL Vagina and spermatheca of different form. 12. Cross section of preputial sac to show ^'ertical ridges or pilasters. Line near figure indicates 1 mm. in length. Figure 12 has same magnification as fig. 2. Illustrations of the Anatomy and of Shells 305 PLATE 34 306 The Molluscan Family Planorbidae PLATE 35 Carinifex 1. Carinifex ponsonbyi E. A. Smith. From Upper Klamath Lake, Oregon. 1. Penial complex showing variation in muscle system. 2-9. Carinifex jackso7iensis J. Henderson. From Jackson Lake, Wyoming; collected by J. Henderson. 2. Simimit of verge showing attachment of retractor muscles. 3. Penial complex showing multiplication of retractor muscles and short penial gland duct. 4. Pseudobranch and pneumostome. 5. Genitalia dissected and organs separated. 6. Portion of genitalia showing relationship of oviduct, sperm duct, ovisperm duct, etc. 7. Same organs as in fig. 6, from above. 8. Albumen gland. 9. Another form of spermatheca. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 307 PLATE 35 308 The Molluscan Faiyiily Planorbidae PLATE 36 Parapholyx 1-9,11,12. Parapholyx ej]usa klamathcnsis F. C. Baker. From Upper Klamath Lake, Oregon; collected by J. Henderson. 1. Whole animal removed from shell. 2. Pseudobranch and related organs. 3. Genitalia dissected and organs separated. 4. Cross section of prostate, uterus, and nidamental gland. 5. Cross section of ovotestis about midway of its length. 6. Cross section of ovotestis toward posterior end. 7. Penial complex showing retractor muscles and short penial gland duct. 8. Penial complex showing nerve and blood vessels. 9. Penial complex cut open to show verge and penial gland with its short duct. At X gland is cut open to show canal. 11. Section of penial gland showing pipe-like cup and canal. 12. Verge showing central position of exit for the sperm canal. 10. Parapholyx cffusa diagonalis J. Henderson. From Crater Lake, Oregon; collected by J. Henderson. 10. Vergic sac and upper part of preputium showing \-erge, muscular ring or dia- phragm, and entrance of penial gland duct into diaphragm. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 309 PLATE 36 310 The Molluscan Family Planorbidae PLATE 37 Planorhula armigera (Say) From Murphy Creek swamp, near Madison, Wisconsin; collected by J. E. Morrison. 1. Section of prostate near middle of gland. 2. Section of prostate near middle. 3. Portion of genitalia showing relationship of o\iduct, sperm duct, ovisperm duct, and carrefour. 4. Genitalia dissected and organs separated, with albumen gland in natural position. 5. Head and foot showing pseudobranch and pneumostome. 6. Section of penial gland. 7. Section of ovotestis to show paired condition of diverticula, which are e.xtended laterally, appearing as though digitate. 8. End of verge to show outlet of sperm canal. 9. Penial complex showing muscles and general form of vergic sac and preputium. 10. Penial complex of small, immature specimen showing wide form of preputium. 11. Section of penial complex showing penial gland spread out and opened, with a short, internal duct. 12. Verge in vergic sac. Line near figure indicates 1 mm. in length. Long line at left of plate is for figs. 6, 7, and 8. Long line at right of plate is for figs. 1 and 2. Illustrations of the Anatomy and of Shells 311 PLATE 37 312 The MoUuscan FainUy Planorbidae PLATE 38 Menetus 1,2,4-10. Menetus opercularis (Gould). From Mountain Lake, San Francisco, Cali- fornia; collected by H. Walton Clark. 1. Genitalia dissected and organs separated. 2. Section of prostate near distal end. 4. Head showing position of pseudobranch. 5. Section of ovotestis. 6. Penial gland with cup expanded. 7. Albumen gland. 8. Section through penial complex showing natural position of penial gland. 9. Albumen gland in natural position overlying stomach. 10. Exterior view of penial complex. 3,11-15. Menetus cooperi calUughjptus (Vanatta). From Crescent City, California; received from Dr. G. D. Hanna. Also from Quatsino Sound, British Columbia; collected by A. Peake. 3. Section of prostate about midway of its length. California sjiecimen. 11. Penial complex from the outside. California specimen. 12. Penial complex. British Columbia specimen. 13. Entire prostate. British Columbia specimen. 14. Cross section of prostate and uterus near front end. British Columbia specimen. 15. End of verge showing central outlet of sperm canal. British Columbia specimen. Line near figure indicates 1 mm. in length. Line at left of fig. 10 is also for figs. 7 and 8. Line at left of fig. 14 is also for figs. 2, 3, 5, 6, 14, and 15. Illustrations of the Anatomy and of Shells 313 314 The MoUuscan Family Planorhidae PLATE 39 Menetus 1-6,9,10. Menetus cooperi callioglyptus (Vanatta). From Quatsino Sound, Vancouver Island, British Columbia; collected by Arthur Peake. Also from Crescent City, California. See plate 38. 1. Genitalia dissected and organs separated. California specimen. 2. Head showing form of jiseudobranch. California specimen. 3. Penial complex in natural position under female complex. British Columbia specimen. 4. Head showing pseudobranch. California specimen. 5. Penial gland attached to wall of preputium. California specimen. 6. Seminal vesicle and ovisperm duct. California specimen. 9. Penial complex showing enlargement of vas deferens as it enters the vergic sac to form an epiphallus. Also form of penial gland in preputium. 10. Penial complex of specimen badly infested with Trematode worms (flukes). Note peculiar form. British Columbia specimen. 7,8. Menetus cooperi F. C. Baker {= planulat us Cooper, preoccupied). From Orcas Island, Puget Sound, Washington; collected by Dr. T. Dale Foster. 7. Penial complex cut open to show verge, penial gland with its short, internal duct, enlargement of \as deferens (epiphallus), and position of retractor muscle. 8. Penial gland in section. Line near figure indicates 1 mm. in length. Line above fig. 6 is also for figs. 5 and 8. Line near fig. 9 is also for fig. 7. Illustrations of the Anatomy and of Shells 315 PLATE 39 316 The Molluscan Family Plauorhidae PLATE 40 Menetus 3-5, 7, 9, 12. Menetus dilatatus (Gould). From pond in field near Unionville, Connecti- cut; collected b.y F. C. Baker and Leslie Brewer. Also from Hyannis, Massa- chusetts; collected by F. C. Baker. 3. Penial complex with preputium pushed u]>waid. 4. Penial complex in natural position, the preputium inflated. 5. Penial complex shown in fig. 4 cut open to show position of verge and i)enial gland. 7. Pseudobranch of specimen from Hyannis, Massachusetts. A broad form. 9. Pseudobranch of specimen from Union\iIle. 12. Genitalia dissected and organs separated. Small specimen shows re\erse side of prostate and vas deferens. 1,2,6,8, 10, 11. Menetus sampsoni (Ancey). From six miles northeast of Dallas, Texas; collected by Dr. E. P. Cheatum. Also from Meremac River, near Stanton, Missouri; collected by Leslie Hubricht. 1. Ovisperm duct and seminal vesicle. Missouri specimen. 2. Penial gland. Texas specimen. 6. Diverticulum of ovotestis with ova in upper part. Texas specimen. 8. Pseudobranch in cylindrical form. Texas specimen. 10. Penial complex cut open to show verge and form of i)enial gland. Texas specimen. 11. External view of penial complex. Texas form. Line at left of fig. 12 equals 1 mm. in length. Line at right of fig. 10 equals 0.5 mm. in length. All figures are greatly enlarged. Illustrations of the Anatomy and of Shells 317 PLATE 40 318 The Molluscan Family Planorbidae PLATE 41 Promenetus exacuous (Say) From Winnebago Lake, near Oshkosh, Wisconsin; collected by F. C. Baker. L Penial complex. Swollen gland causing bulge in preputium. 2. Penial complex, external view, showing a single retractor muscle. 3. Penial complex opened to show verge and penial gland. 4. Cross section of ovotestis about midway of its length. 5. Cross section of prostate near anterior end. 6. Ovotestis viewed from left side of animal, showing diverticula. 7. Albumen gland from the side. 8. Head and neck of animal showing pseudobranch. 9. Head of animal showing verge and jienial gland ]>rojecting from the male genital opening. 10. Genitalia dissected and organs separated. Line near figure indicates 1 mm. in length. Line at left of figs. 4 and 5 is for both of these figures. Figure 7 has the same magnification as fig. 10. Illustrations of the Anatomy and of Shells 319 PLATE 41 320 The Molluscan Family Planorbidae PLATE 42 Promenetus 1,3,7,12. Promenetus exacuous (Say). From Mott Lake, Wainwright Park, Alberta; collected by Dr. Stiles. Received from Canadian National Museum. 1. Pseudobranch fully expanded. 3. Penial gland in preputium which has been cut open and the pilasters separated. 7. Section of penial gland. 12. Side view of preputium showing penial gland and end of verge passing through the diaphragm. 2,4,5,8-11,13. Promenetus exacuous megas (Dall). From Paul Lake, British Colum- bia; collected by Dr. D. S. Rawson. 2. Head of animal showing pseudobranch. 4. Penial gland from above showing trough-like duct leading to muscular ring or diaphragm at upper part of preputium. 5. Penial complex in natural position. 8. Cross section of ovotestis near middle. 9. Cross section of ovotestis near posterior end. 10. Portion of genitalia showing relation.ship of ducts. 11. Cross section of prostate. An unusual form with split diverticula. 13. Terminal end of verge showing central exit for sperm canal, small fleshy ap- jiendage, and peculiar ring near end. 6. Promenetus umbilicatcUus (Cockerell). From Wainwright Park, Alberta; collected by Dr. Stiles. Received from Canadian National Museum. 6. Pseudobranch and jineumostome. Line near figure indicates 1 mm. in length. Vertical line bordering figs. 8, 9, and 13 is also for figs. 7, 10, and 11. Illustrations of the Anatomy and of Shells 321 322 The Molluscan Family Planorbidae PLATE 43 Pronienetus umbilicatellus (Cockerell) From lake southwest of Mott Lake, Wainwright Park, Alberta; collected by Dr. Stiles. Received from the Canadian National Museum. L Genitalia dissected and organs separated. 2. Head showing pseudobranch and pneumostome. 3. Penial complex opened to show penial gland, verge, diaphragm, etc. 4. Penial complex in natural position. 5. Albumen gland from below. 6. Cross section of prostate and uterus about midway of length. 7. Portion of genitalia showing union of oviduct and sperm duct, also carrefour. 8. Cross section of ovotestis. Note developing ova. 9. Penial gland showing channel-like duct, viewed from above. 10. Penial gland viewed from the side showing how gland is folded and base attached to preputium at lower end. 11. Section of penial gland. 12. Termination of \erge showing small fleshy appendage at end. Line near figure indicates 1 mm. in length. Figures 5, 6, 7, and 8 have same measurements as fig. 1. Figures 9. 10, 11, and 12 have same measurements as fig. 3. Illustrations of the Anatomy and of Shells 323 324 The Molluscan Family Planorbidae PLATE 44 Kidney of Helisoma 1. H. anceps (Menke). Gillespies Pond, Collinsville, Connecticut. 2. H. trivolvis (Say). Oneida Lake, New York. 3. H. corpulcntum (Say). Lake of the Woods, Ontario, Canada. 4. H. scalare (Jay). Lake Butler, Florida. 5. H. duryi normale Pilsbry. Canal at Boj-nton, Florida. Sections of kidneys 6. H. oregonense (Tryon). Tooele Co., Oregon. Near lower end of kidney. 7. H. anceps (Menke). Gillespies Pond. Collinsville, Connecticut. Above middle. 8. H. a. latchfordi (Pilsbry). Meach Lake, Quebec, Canada. Near middle. 9. H. trivolvis (Say). Oneida Lake, New York. About middle. 10. H. t. macrostomum (Whiteaves). Bayfield, Wisconsin. About middle. IL H. t. lentum (Say). New Orleans, Louisiana. Lower end. 12. H. pilsbryi (F. C. Baker). Lake Chetek, Wisconsin. Near Middle. 13. H. truncatum (Miles). Winnebago Lake, Wisconsin. Near middle. 14. //. magnificum (Pilsbry). Near Wilmington, North Carolina. Near middle. 15. H. corpulentuyn (Say). Lake of the Woods, Ontario. Near middle. 16. H. c. multicostntum F. C. Baker. Crooked Pine Lake, Ontario. Lower end. 17. H. p. infracarinatum F. C. Baker. Basswood River Rapids, Ontario. At middle. 18. H. occidentale (Cooper). Klamath Lake, Oregon. Near middle. 19. H. o. depressum F. C. Baker. Klamath Lake, Oregon. Near middle. 20. //. (raskii (Lea). Buena Vista Canal, California. Near middle. 21. H. subcrenatnm (P.. P. Carpenter). McMurray, Skagit Co., Washington. Near middle. 22. H. plexatum (Inger.soll). Columbine Lake, Colorado. Lower end. 23. H. horni (Tryon). Paul Lake, British Columbia. Near middle. 24. H. tenue calij orniense F. C. Baker. Shandon, California. Near middle. 25. H. scalare (Jay). Lake Butler, Florida. Near middle. 26. H . duryi normale Pilsbry. Canal at Boynton, Florida. Near middle. Line near figure indicates 1 mm. in length. Arrow indicates point at which section was made. lUustratioiis of the Anatomy and of Shells 325 PLATE 44 326 The Molluscan Family Planorbidae PLATE 45 Kidneys of Planorbidae 1. Australorbis glabratus (Say). Puerto Rico. 2. Carinifex pojisonbyi E. A. Smith. Klamath Lake, Oregon. 3. Planorbula armigera (Say). Near Oshkosh, Wisconsin. 4. H. tenue californiense F. C. Baker. Near Redlands, California. 5. H. tenue californiense F. C. Baker. Section at B in fig. 4. 6. H. tenue californie7i.se F. C. Baker. Section at A in fig. 4. 7. Australorbis glabratus (Say). Section at E in fig. I. 8. Australorbis glabratus (Say). Section at D in fig. I. 9. Australorbis glabratus (Say). Section at C in fig. L 10. Australorbis glabratus (Say). Section at B in fig. L IL Australorbis glabratus (Say). Section at A in fig. L 12. Carinifex ponsonbyi E. A. Smith. Section near middle. 13. Planorbula armigera (Say). Section near middle. 14. Four spherical bodies from ridge of kidney. Greatly enlarged. 15. Helisoma campanulatum wisconsinense (Winslow). Section through upper part. 16. H. campanulatum. wisconsinense (Winslow). Section through middle. 17. H. campanulatum wisconsinense (Winslow). Section through lower end. 18. Planorbarius corneus (Linn.). Section through lower end. From Poland. 19. Indoplanorbis exustus (Deshayes). Section near middle. From India. Line near figure indicates 1 mm. in length. Letters A, B, C, D, E, etc., indicate points of kidney through which sections have been made and are figured. Illustrations of the Anatomy and of Shells IN 327 PLATE 45 328 The Molluscan Family Planorbidae PLATE 46 Kidneys of Planorbidae 1. Parapholyx effusa klamathensis F. C Baker. Klamath Lake, Oregon. 2. P. effusa klamathensis F. C. Baker. Section near middle. 3. Promenetus exaciious (Say). Winnebago Lake, near Oshkosh, Wisconsin. 4. Promenetus exacuous (Say). Section near middle. Line is 0.3 mm. long. 5. Menetus dilatatus (Gould). Unionville, Connecticut. 6. Menetus dilatatus (Gould). Section near middle. Line is 0.3 mm. long. 7. Menetus cooperi callioglyptus (Vanatta). Vancouver Island, British Columbia. 8. M. cooperi callioglyptus (Vanatta). Section near middle. 9. Planorbis planorbis (Linn.). Near Warsaw, Poland. 10. Planorbis planorbis (Linn.). Section near middle. n. Tropicorbis riisei (Dunker). Puerto Rico. 12. Tropicorbis riisei (Dunker). Section near middle. 13. Tropicorbis havanensis (Pfeiffer). Section near middle. 14. Drepanotrema hoffmani F. C. Baker. Lsabela, Puerto Rico. 15. Drepanotrema hoffmani F. C. Baker. Section at ])oint indicated by arrow. 16. Drepanotrema lucidum (Pfeiffer). Section near middle. 17. Hippeutis complanatus (Linn.). Near Warsaw, Poland. 18. Hippeutis complanatus (Linn.). Section at point indicated by arrow. Line equals 0.5 mm. in length. 19. Bathyomphalus contortus (Linn.). Near Warsaw, Poland. 20. Bathy<>mi>halus contortus (Linn.). Section at jioint indicated by arrow. Line equals 0.5 mm. in length. Except where otherwise mentioned the line near the figure indicates 1 mm. in length. Illustrations of the Anatomy and of Shells 329 330 The Molluscan Family Planorbidae PLATE 47 Kidneys of Planorbidae 1. Gyraulus parvus (Say). Winnebago Lake, Wisconsin. 2. Gyraulus circumstriatus (Tryon). Wainwright Park, Alhoifa. 3. Gyraulus deflcctus ohliquus (DeKay). Near Quebec, Canada. 4. Gyraulus vermicularis (Gould). Near San Francisco, California. 5. Gyraulus parvus (Say). Section near middle. Line equals 0.5 mm. 6. Gyraulus circumstriatus (Tryon). Section near middle. Line equals 0.5 nmi. 7. Gyraulus vermicularis (Gould). Section near middle. Line equals 0.5 nun. 8. Gyraulus convexiusculus (Hutton). India. Section near middle. 9. Gyraulus siniilarls (F. C. Baker). Section near middle. 10. Gyraulus deflcctus obliquus (DeKay). Section near middle. IL Gyraulus latestornus F. C. Baker. Section below middle. Figures 6 to 11 have same magnification as fig. 5. 12. Anisus vortex (Linn.). Near Wansaw, Poland. 13. Ayiisus spirorbis (Linn.). Near Warsaw, Poland. 14. Ayiisus vortex (Linn.). Section near middle. Line equals 0.5. mm. 15. Anisus leucoslomus (Millet). Section near middle. Line equals 0.5 mm. 16. Anisus spirorbis (Linn.). Section near middle. Line equals 0.5 mm. 17. Gyraulus convexiusculus (Hutton). India. 18. Gyraulus hirsutus (Gould). Canada. 19. Gyraulus hirsutus (Gould). Section below middle. 20. Armiger crista (Linn.). Wi.sconsin. 21. Anniger crista (Linn.). Section near middle. Line equals 0.5 nnu. 22. Segmenlina nilida (Miiller). Near Warsaw, Pohmd. 23. Segmentina nitida (Miiller). Section below middle. Line equals 0.5 nun. 24. Polypylis hemisphaerula (Benson). Peiping, China. 25. Polypylis hemisphaerula (Benson). Section near middle. Line equals 0.5 mm. 26. Intha capitis Annandale. South Shan State, Burma. 27. Intha capitis Annandale. Section below middle. Line equals 0.25 mm. Linless otherwi.se stated the line near the figure indicates 1 nun. ni length. Illustrations of the Anatomy and of Shells 331 PLATE 47 332 The Molluscan Family Planorhidae PLATE 48 Digestive System of Planorbidae 1. Helisoma trivolvis (Say). Entire digestive system except liver. From above. 2. Helisoma trivolvis (Say). Region of the stomach from below. 3. Carinifex ponsonbyi E. A. Smith. Region of stomach from below. 4. Promenetus exacuous (Say). Region of stomach from above. 5. Promenetus exacuous (Say). Region of stomach from below. 6. Planorbis planorbis (Linn.). Region of stomach from above. 7. Planorbis planorbis (Linn.). Region of stomach from below. 8. Bathyomphalus contortus (Linn.). Portion of digestive system from above. 9. Atistrnlorbis glabratns (Say). Region of stomach from above. 10. AuMralorbis glabratus (Say). Region of stomach from below. IL Drepanotrema hicidum (Pfeiffer). Region of stomach from above. 12. Hippeutis complanatus (Linn.). Region of stomach from above. 13. Gyraulus albus (Miiller). Region of stomach from above. 14. Gyraulus parvus (Say). Region of stomach from above. 15. Armiger crista (Linn.). Region of stomach from above. 16. Segmentina nitida (Miiller). Region of stomach from above. 17. Helisoma anceps (Menke). Nerves and blood vessels to penial complex. Nerve from left cerebral ganglion. 18. Nerve ring of Helisoma trivolvis (Say), from above. Line near figure indicates 1 mm. in length Illustrations of the Anatomy and of Shells 333 PLATE 48 334 The Molluscan Family Planorbidae PLATE 49 Jaws of Planorbidae 1. Helisoma anceps (Menke). Chetek Lake, Wisconsin. 2. Helisoma trivolvis (Say). Devils Lake, Wisconsin. Small fig. indicates striation. 3. Helisoma truncatum (Miles). Oshkosh, Lake Winnebago, Wisconsin. 4. Helisoma scalare (Jay). Lake Butler, Florida. 5. Helisoma pilsbryi (F. C. Baker). Chetek Lake, Wisconsin. 6. Helisoma oregojiense (Tryon). Tooele Co., Utah. 7. Helisoma subcrenatum (P. P. Carpenter). Gypsum, Colorado. Superior jaw. 8. H. pilsbryi injracarinatum F. C. Baker. Rideau River, Ontario. Superior jaw. 9. Helisoma horni (Tryon). Paul Lake, British Columbia. 10. Helisoma plexatum (Ingersoll). Grand Mesa, Colorado. Superior jaw. IL H. campanulatum smithi (F. C. Baker). Douglas Lake, Michigan. 12. Helisoma traskii (Lea). Outlet of Kern Lake, California. Superior jaw. 13. Helisoma occidentale (Cooper). Klamath Lake, Oregon. Superior jaw. 14. H. duryi normale Pilsbry. Forty miles west of Miami, Florida. Superior jaw. 15. Helisoma corpulentum (Say). Bamiji Lake, Ontario, Canada. 16. Helisoma magnificum (Pilsbry). Near Wilmington, North Carolina. 17. Carinifex jacksonejisis J. Henderson. Jackson Lake, Wyoming. Jaw and cartilage from the side. 18. Carinifex jacksonensis J. Henderson. Jaw from above. 19. Carinifex ponsonbyi E. A. Smith. Klamath Lake, Oregon. Jaw and cartilage from below. 20. Helisoma campatudatum smithi (F. C. Baker). Douglas Lake, Michigan. Vertical striation on jaw. Highly magnified. Line at right of fig. 1 indicates 1 mm. in length. Line at lower extreme left is for figs. 18 and 19 and represents 0.5 mm. in length. Middle line is for fig. 6. Line at right is for figs. 2, 3, 4, 5, and 7 to 16. Figure 17 is diagrammatic. Illustrations of the Anatomy and of Shells 335 336 The Molluscan Family Planorbidae PLATE 50 Jaws of Planorbidae 1. Helisoma tenae calijornicnse F. C. Baker. Shandon, California. 2. Planorhiila armigera (Say). Muri)hy Creek, near Madison, Wisconsin. 3. Pkmorbula jenksii (H. F. Carpenter). Unionville, Connecticut. 4. Porapholyx effusa klamathensis F. C. Baker. Klamath Lake, Oregon. 5. Porapholyx effusa diagonalis J. Henderson. Crater Lake, Oregon. 6. Menetus sampsoni (Ancey). Near Stanton, Missouri. 7. Menetus cooperi caUioglyptus (Vanatta). Vancouver Island, British Columbia. 8. Promenetus exacuous (Say). Winnebago Lake, Wisconsin. 9. Menetus dilatatus (Gould). Unionville, Connecticut. 10. Indoplanorhis exustus (Deshayes). North Shan State, Burma. n. Tropicorbis obstructus (Morelet). New Orleans, Louisiana. Superior jaw. 12. Tropicorbis riisei (Dunker). Puerto Rico. 13. Australorbis glabratus (Say). Puerto Rico. 14. Planorbarius corneus (Linn.). Near Warsaw, Poland. 15. Promenetus umbilicatellus (Cockerell). Wainwright Park, Alberta. 16. Gyraulus parvus (Say). Winnebago Lake, Wisconsin. 17. Gyraulus hirsutus (Gould). Lake Nipissing, Ontario, Canada. 18. Gyraulus deflectus obliquus (DeKay). Taylor Lake, Quebec, Canada. 19. Gyrauhis vermicrdaris (Gould). Near San Francisco, California. 20. Armiger crista (Linn.). Wisconsin. 21. Planorbis planorbis (Linn.). Near Warsaw, Poland. 22. Gyraidus circumstriatus (Tryon). Wainwright Park, Alberta. 23. Intha capitis Annandale. Burma. 24. Segmentina nitida (Muller). Near Warsaw, Poland. 25. Ayiisus spirorbis (Linn.). Near Warsaw, Poland 26. Drepanotrema hoffmani F. C. Baker. Puerto Rico. 27. Drepanotrema lucidum (Pfeiffer). Cuba. 28. Gyraulus albus (Muller). Near Warsaw, Poland. Figures are greatly enlarged. Sizes are disproportionate. Illustrations of the Anatomy and of Shells 337 PLATE 50 338 The Molluscan Family Planorbidae PLATE 51 Development of Helisoma scalare (Jay) 1. Egg capsule containing 28 eggs, observed on March 1, 1932. Each egg is marked to correspond with the numbered figures below. Line near figure indicates 1 mm. in length. 2. The 24-cell stage of segmentation in egg No. 7. March 7. 3. Gastrula stage of segmentation in egg No. 7. March 8. 4. Post-trochophore stage in egg No. 11. March 4. 5. Post-trochophore stage in egg No. 11. March 5. 6. Veliger stage of embryo in egg No. 11. March 9. 7. Veliger stage of embryo in egg No. 8. Front view. March 9. 8. Veliger stage of embryo in egg No. 8. Side view. March 9. 9. Veliger stage of embryo in egg No. 8. Top view. March 10. 10. Embryo in egg No. 3. March 12. 11. Embryo in egg No. 1 showing heart and stomach. March 11. 12. Young snail in egg No. 3. March 14. A similar young snail was observed in egg No. 20 on March 14. Shell growth distinct. 13. Young snail just out of egg No. 1. March 15. 14. Young snail two days out of egg No. 1. March 16. Shell now shows both growth lines and spiral striae. Line at lower left indicates 1 mm. in length Illustrations of the Anatomy and of Shells 339 340 The Molluscan Family Planorbidae PLATE 52 Nidifieation in Planorbidae 1-3. Helisoma scalare (Jay). Lake Butler, Florida. L Five eggs laid March 13, 1931. 2. Fourteen eggs laid April 1, 1931. 3. Ten eggs laid April 2, 1931. 4-5. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. 4. Twenty eggs laid June 5, 1933. 5. Ten eggs laid May 27, 1933. 6-8. Helisoma eluryi normale Pilsbry. Gainesville, Florida. 6. Two eggs laid Dec. 25, 1931. 7. Three eggs laid Dec. 26, 1931. 8. Four eggs laid Jan. 17, 1932. 9-11. Helisoma duryi cudiscus Pilsbry. Silver Springs, Florida. 9. Five eggs laid Dec. 13, 1931. 10. Nine eggs laid Feb. 6, 1932. 11. Twelve eggs laid Feb. 10, 1932. 12. Helisoma duryi normale Pilsbry. Tamiami Trail, 40 miles west of Miami, Florida. 12. Sixteen eggs laid Jan. 17, 1932. 13. Helisoma traskii (Lea). Buena Vista Canal, outlet of Kern Lake, California. 13. Alcoholic specimen wath 50 eggs laid on adult shell. 14-16. Gyraulus circumstriaius (Tryon). Wainwright Park, Alberta. 14. Nucleated ovum from ovotestis. 15. Spermatozoa from o\otestis. Typical (eupyrene) spermatozoa as seen in active group. 16. Eupyrene spermatozoa from the side and from abo\'e. Line near figs. 1-13 indicates 1 mm. in length. Line near figs. 14-16 indicates 25 microns in length. Illustrations of the Anatomy and of Shells 341 PLATE 52 342 The Molluscan Family Planorbidae PLATE 53 Radulae of Helisotna In the plates of radulae, the number under the central tooth (as 15, 80, 98, 50, and 75 on this plate) indicates the number of the transverse row, counting from the front end of the radula. The numbers following indicate the number of the tooth in this row, counting from the central tooth, the first lateral tooth being nvuiiber 1. The line at the lower part of the plate indicates 25 microns. 1. Helisoma anceps (Menke). Maple River, Michigan. 15, center tooth; 1-5, lateral teeth; 6, 7, intermediate teeth; 8-14, marginal teeth. 2. Helisoma anceps (Menke). Chautauqua Lake, New York. 80, center tooth; 1-5, lateral teeth; 6-8, intermediate teeth; 9-13, marginal teeth. 118, center tooth (of 118th row) with first left marginal beside it. 3. Helisoma anceps (Menke). Unionville, Connecticut. 98, center tooth; 1, 2, lateral teeth; 6, 7, intermediate teeth; 8, 9, marginal teeth on right side; 11-16, marginal teeth on left side of row. 90, 90th row, center tooth; 5, lateral tooth with two ectocones; 8, intermediate tooth; 9, 10, marginal teeth. 4. HcILsoma anceps sayi F. C. Baker. Bayfield, Wisconsin. 50, center tooth in 50th row; 1-5, lateral teeth; 6, 7, intermediate teeth; 8-14, marginal teeth. 75, 75th row, pathologic center tooth; 1-5, pathologic lateral teeth. Illustrations oj the Anatomy and of Shells 343 PLATE 53 344 The Molluscan Family Planorbidae PLATE 54 Radulae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. L Helisoma nnceps percarinatum (Walker). Douglas Lake, Michigan. 85, center tooth; 1-6, lateral teeth; 7-9, intermediate teeth; 10-23, marginal teeth. 100, 100th row, center tooth; 1-3, lateral teeth, pathologic (2 entocones) ; 9, intermediate tooth; 10, marginal tooth. 2. Helisoma anceps royalense (Walker). Bamiji Lake, Ontario, Canada. 60, center tooth; 1-6, lateral teeth; 7-9, intermediate teeth; 10-19, marginal teeth. 3. Helisoma anceps cahni F. C. Baker. Big Muskallonge Lake, Wisconsin. 60, center tooth; 1-6, lateral teeth; 7-9, intermediate teeth; 10-18, marginal teeth. 4. Helisoma anceps latchjordi (Pilsbry). Meach Lake, Quebec, Canada. 51, center tooth; 1-6, lateral teeth; 7-9, intermediate teeth; 10-26, marginal teeth. 60, an abnormal center tooth from another membrane, with accessory lateral cusps above the normal center cusps. Illustrations of the Anatomy and of Shells 345 346 The Molluscan Family Planorbidae PLATE 55 Radulae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. 1. Helisoma trivolvis (Say). Oneida Lake, New York. 60, center tooth; 1-7, lateral teeth; 8-10, intermediate teeth; 11-18, marginal teeth. 2. Helisoma trivolvis {Sa.y) ^ pseudotrivolvis F. C. Baker, near lentum Say. From Reelfoot Lake, Tennessee. 150, center tooth; 1-7, lateral teeth; 8-10, intermediate teeth; 11-13, marginal teeth. 3. Helisoma trivolvis lejitum (S&y) ^ pseudotrivolvis F. C. Baker. Reelfoot Lake, Tennessee. 107, center tooth; 1-7, lateral teeth; 8-10, intermediate teeth; 11-14, marginal teeth; 50, 50th center tooth of another row. 4. Helisoma trivolvis (Say). Sturgeon Bay, Wisconsin. 70, center tooth; 1-6, lateral teeth; 7-11, intermediate teeth; 13, 14, marginal teeth. 5. Helisoma chautauquense F. C. Baker. Chautauqua Lake, New York. 102, center tooth; 1-7, lateral teeth; 8-11, intermediate teeth; 12-15, marginal teeth. 6. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. 96, center tooth; 1-8, lateral teeth; 9-11, intermediate teeth; 12-15, marginal teeth. 7. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. 16-25, marginal teeth; 4, 4th lateral tooth from another row, with two entoconic cusps. Illustrations of the Anatomy and of Shells 347 11 12 1 ^^150 I 2 3 4^-~~— ^ 1234 PLATE 55 348 The Molluscan Family Plauorbidae PLATE 56 Radiilae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. 1. Helisoma winsloivi (F. C. Baker). Little Arbor Vitae Lake, Wisconsin. 70, center tooth; 1-13, lateral teeth; 14, 15, intermediate teeth; 17-19, marginal teeth. 2. Helisoma trivolvis macrostovium (Whiteaves). Bayfield, Wisconsin. 53, center tooth; 1-8, lateral teeth; 9-13, intermediate teeth; 14-23, marginal teeth. 3. Helisoma pilsbryi (F. C. Baker). Chetek Lake, W'isconsin. 100, center tooth; 1-8, lateral teeth; 10-12, intermediate teeth; 13-23, marginal teeth. 4. Helisoma pilsbryi infracarinatiim F. C. Baker. Basswood River Rapids, Ontario. 132, center tooth; 1-9, lateral teeth; 10-14, intermediate teeth; 15-21, marginal teeth. 5. Helisoma pilsbryi injracarinatnm F. C Baker. Rideau River, Ontario. Varying toward pilsbryi. 115, center tooth; 1-13. lateral teeth; 14. 15, interme- diate teeth; 16-29. marginal teeth. Illustrations of the Anatomy and of Shells 349 PLATE 56 350 The Molluscan Family Planorbidae PLATE 57 Radulae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. L Helisoma truncatum (Miles). Winnebago Lake, near Oshkosh, Wisconsin. Normal membrane. 85. center tooth; 1-7, lateral teeth; 9-11, intermediate teeth; 13-20, marginal teeth. 2. Helisoma truncatum (Miles). Winnebago Lake, Wisconsin. Abnormal membrane, with many split cusps on teeth. 90, center tooth; 1-8, lateral teeth, 6 and 7 with bifid entoconic cusps and 5, 6, and 7 with split ectoconic cusps; 9-11, intermediate teeth with modified ectocones; 12-21, marginal teeth. 3. Helisoma corpulent um (Say). Lac la Croix, Ontario, Canada. 48, center tooth; 1-8, lateral teeth; 9-12, intermediate teeth; 13-25, marginal teeth. 4. Helisoma magnijicum (Pilsbry). Near Wilmington, North Carolina. 90, center tooth; 1-14, lateral teeth; 16-23, intermediate teeth; 24-41, marginal teeth. The small numerals on the first lateral of fig. 1 indicate the following parts of the tooth: 1, entocone or inner cusp; 2, mesocone or middle cusp; 3, ectocone or outer cusp; 4, base of attachment to radula membrane. In 16 of fig. 1, the small numeral 2 indicates the position of the mesocone in a marginal tooth. Illustrations of the Anatomy and of Shells 351 16 17 1 22 25 25 26 27 28 32 41 PLATE 57 352 The Molluscan Family Plauorbidae PLATE 58 Radulae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. L Helisoma whiteavesi F. C. Baker. Mille Lacs, Ontario, Canada. 105, center tooth; 1-16, lateral teeth; 17-19, intermediate teeth; 20-35, marginal teeth. 23, a pathologic tooth in another row. 12, a lateral tooth on the left side with split cusps. 2. Helisoma corpuhntum vermilionense F. C. Baker. Vermilion Lake, Minnesota. 101, center tooth; 1-7, lateral teeth; 9-12, intermediate teeth; 13-21, marginal teeth. 3. Helisoma corpulent um inidticostatum F. C. Baker. Kahniinminanikok Lake, Ontario, Canada. 60, center tooth; 1-7, lateral teeth; 11-14, intermediate teeth; 15-41, marginal teeth. 4. Helisoma plexatum (Ingersoll). Teton River, near Rexburg, Idaho. 44, center tooth; 1-8, lateral teeth, 1 and 4 with mesocones worn or pathologic; 10-13, intermediate teeth; 13-16, marginal teeth. The two 13 figures show how this tooth differed in two rows, being an intermediate tooth in one row and a marginal tooth in another row. 5. Helisoma plexatum (Inger.soll). The 120th row in another membrane from a Teton River specimen. 16-18, modified marginal teeth. 6. Helisoma plexatum (Ingersoll). Smartweed Lake, Colorado. 13, a lateral tooth; 14-15, marginal teeth. Illustrations of the Anatoiny and of Shells 353 PLATE 58 354 The Molluscan Family Planorbidae PLATE 59 Radulae of Helisoma See remarks on plate 53. Line at bottom of plate indicates 25 microns in length. 1. Helisoma plexatum (Ingersoll). Grand Mesa, Colorado. 60, center tooth; 1-12, lateral teeth; 13-17, intermediate teeth; 18-22, marginal teeth. 2. Helisoma plexatum (Ingersoll). Columbine Lake, Colorado. 95, center tooth; 1-10, lateral teeth; 11-12, intermediate teeth; 13-15, marginal teeth. 3. Helisoma tenue calijorniense F. C. Baker. San Bernardino Mts., California. Normal teeth. 60, center tooth; 1-11, lateral teeth; 12, 13, intermediate teeth; 14-21, marginal teeth. 4. Helisoma tenue calijorniense F. C. Baker. San Bernardino Mts., California. Abnormal teeth, the lateral teeth with extra cusps on both entocones and ecto- cones and with mesocone much modified. 60, center tooth; 1-10, lateral teeth; 11, 12, intermediate teeth; 12-17, marginal teeth. 5. Helisoma subcrenatum (P. P. Carpenter). Variety. Pass Lake, Puget Sound, Wash- ington. 96, center tooth; 1-15, lateral teeth; 16-18, intermediate teeth; 19-28, marginal teeth. 6. Helisoma tenue calijorniense F. C. Baker. San Bernardino Mts., California. An abnormal 11th lateral tooth. Illustrations of the Anatomy and of Shells 355 PLATE 59 356 The Molluscan Family Planorhidae PLATE 60 Radulae of Helisoma See remarks on plate 53. Line at lower rig;ht of plate indicates 25 microns in length. L Helisoma subcrciialum (P. P. Carpenter). Variety. Lost Lake, Paget Sound, Washington. 73, center tooth; 1-7, lateral teeth; 12, 13, intermediate teeth; 15-20, marginal teeth. 2. Helisoma subcrenatum (P. P. Carpenter). Variety. Lost Lake, Puget Sound, Wash- ington. 88, abnormal center tooth; 5. lateral tooth with bicuspid entocone. 3. Helisoma subcrenatum (P. P. Carpenter). Skagit Co., Washington. 90, center tooth; 1, 7. lateral teeth; 12, intermediate tooth; 17, 20, marginal teeth. 4. Helisoma traskii (Lea). Outlet of Kern Lake, California. 82nd row, 9, intermediate tooth; 10. 11, marginal teeth. 5. Helisoma traskii (Lea). Outlet of Kern Lake, California. 90, center tooth; 1-9, lateral teeth; 10, 11, intermediate teeth; 12-22, marginal teeth. 6. Helisoma traskii (Lea). Outlet of Kern Lake, California. 80th row, 9, intermediate tooth; 10, first marginal tooth. 7. Helisoma horni (Tryon). Paul Lake, British Columbia. 60, center tooth; 1-9, lateral teeth; 10-14, intermediate teeth; 15-32, marginal teeth. 4, fourth tooth in another row. Illustrations of the Anatomy and of Shells 357 PLATE 60 358 The Molluscan Family Planorbidae PLATE 61 Radulae of Helisoma See remarks on plate 53. Line at lower right of plate indicates 25 microns in length. 1. Helisoma occidentale (Cooper). Klamath Lake, Oregon. 45, center tooth; 1-8, lateral teeth; 9-12, intermediate teeth; 13-23, marginal teeth. 2. Helisoma subcrenatum (P. P. Carpenter). Cottonwood Pass, Gypsum, Colorado. 95, center tooth; 1-8, lateral teeth; 9-12, intermediate teeth; 13-20, marginal teeth. 3. Helisoma oregonense (Tryon). Tooele Co., Utah. 58, center tooth; 1-8, lateral teeth; 9, 10, intermediate teeth; 11-21, marginal teeth. Illustrations of the Anatomy and of Shells 359 C^X ,^ ^^ 18 3 PLATE 61 360 The Molluscan Family Planorbidae PLATE 62 Radiilae of Helisoma See remarks on plate 53. Line at lower right of plate indicates 25 microns in length. L Helisoma campanulatum (Say). Oneida Lake, New York. 60, center tooth; 1-7, lateral teeth; 8, 9, intermediate teeth; 10-20, marginal teeth. 2. Helisoma campanulatum. wisconsincnse (Winslow). Little Arbor Vitae Lake, Wis- consin. 50, center tooth; 1-8, lateral teeth; 9, 10, intermediate teeth; 11-15, marginal teeth. 3. Helisoma campanulatum canadcnse F. C. Baker. Bamiji Lake, Ontario, Canada. 52, center tooth; 1-8, lateral teeth; 9, 10, intermediate teeth; 11-20, marginal teeth. 4. Helisoma campanulatum smithi (F. C. Baker). Douglas Lake, Michigan. 60, center tooth; 1-8, lateral teeth; 9, 10, intermediate teeth; 11-19, marginal teeth. Illustrations of the Anatomy and of Shells 361 362 The Molluscan Family Planorbidae PLATE 63 Radulae of Helisoma See remarks on plate 53. Line at lower right of plate indicates 25 microns in length. 1. Helisoma trivolvis fallax (Haldeman). Cambridge, Massachusetts. 60, center tooth; 1-7, lateral teeth; 10, intermediate tooth; 11-23, marginal teeth. 2. Helisoma tenue californiense F. C. Baker. Shandon, California. 77, center tooth; 1-11, lateral teeth; 12. intermediate tooth; 13-19, marginal teeth. 100th row. Numerals 1-11, lateral teeth with multiple cusps on entocone and ectocone. 3. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. 60, center tooth; 1-9, lateral teeth; 10, 11, intermediate teeth; 12-20, marginal teeth. 4. Helisoma duryi eudiscus Pilsbry. Silver Springs, Florida. 84, center tooth; 1-10, lateral teeth; 11, 12, intermediate teeth; 12-22, marginal teeth. Illustrations of the Anatomy and of Shells 363 r"^ 14 15 17 4 PLATE 63 364 The MoUuscan Family Planorbidae PLATE 64 Radulae of Helisoma See remarks on plate 53. Line at lower right of plate indicates 25 microns in length. L Helisoma scalare (Jay). Lake Butler, Florida. 89, center tooth; 1-8, lateral teeth; 9-11, intermediate teeth; 12-21, marginal teeth. 2. Helisoma scalare (Jay). Lake Butler, Florida. 86, center tooth of another specimen; 1-6, lateral teeth. 3. Helisoma duryi normale Pilsbry. Tamiami Trail, 40 miles west of Miami, Florida. 110, center tooth; 1-11, lateral teeth; 12, intermediate tooth; 13-29, marginal teeth. 12, lower right, 12th tooth (marginal) in another row of teeth. 4. Helisoma duryi normale Pilsbry. Paines Prairie, Florida. 55, center tooth ; 1-9, lateral teeth; 10, intermediate tooth; 11-26, marginal teeth. 140, center tooth; 1-10, lateral teeth; 11, intermediate tooth; 12-20, marginal teeth. Illustrations of the Anatomy and of Shells 365 PLATE 64 366 The Molluscan Family Planorbidae PLATE 65 Radulae of Planorbula, Parapholyx, and Carinifex See remarks on plate 53. Line at lower left of plate indicates 25 microns in length. 1. Planorbula armigera (Say). Murphy Creek, near Madison, Wisconsin. 128, center tooth; 1-6, lateral teeth; 9, 11, intermediate teeth; 12-19, marginal teeth. 2. Planorbula jenksii (H. F. Carpenter). Unionville, Connecticut. 105, center tooth; 1-5, lateral teeth; 9, 11, intermediate teeth; 12-19, marginal teeth. 3. Parapholyx effusa klamathensis F. C. Baker. Klamath Lake, Oregon. 60, center tooth; 1-8 lateral teeth; 9-11, intermediate teeth; 13-19, marginal teeth. 4. Cariyiifex jackso7ic7isi.\^ 11 12 13 14 15 16 394 The Molluscan Family Planorbidae PLATE 79 Shells of Planorbidae 1-3. Segmentina nitida (Miiller). Swamp on a meadow in Czerniakow, a suburb of Warsaw, Poland. Baker coll., 3972. X4. 4-Q. Hip pe litis fontanus {Ijightioot)=^ cornplanat us (Linn.). Damsells Mill Pond, Painswich, West Strand, England. Baker coll., 1256. X6. 7-9. Polypylis largiUiarti (Phil.) ^ hemisphaerula (Benson). Peiping, China. Baker coll., 5973. X4. 10-12. Platytaphius heteropleurus (Pils. & Van.). Lake Titicaca, Peru. Baker coll., 3974. X2. 13-15. Mcnetus dilatatus (Gould). Wrights Dike, Duxbury, Massachusetts. Baker coll., 3978. X4. 16-18. Drepanolrcma anatinum (Orb.). Figures 16, 17, Para, Brazil. U.S.N.M., 348535; fig. 18, Para, Brazil M.C.Z., 72832. X5. 19-21. Promenetus exacuous (Say). Small brook west bank Caj^uga Lake, near Cayuga, New York. Baker coll., 1140. X4. 22-24. Mcnetus opercidaris (Gould). San Francisco, California. U.S.N.M., 227303. X4. 25-27. Planorbida armigera (Say). Thief River Falls, Minnesota. U.I., 27093. X4. 28-30. Planorbida ivheatlcyi (Lea). Boligee, Alabama. Baker coll., 1140. X4. 31,32. PerriniUa corddlcriann (Hannibal). Truckee Lake Beds, Nevada. Hill near Haw- thorne, on Belmont Stage Road, Nevada. Hannibal, Proc. Mai. Soc, X, plate 6, fig. 16, plate 8, fig. 34. About natural size. 33-35. Indoplanorbis exustus (Desh.). Figures 33, 34, Bombay, India. Baker coll., 1231; fig. 35, Calcutta, Lidia, Baker coll., 2229. Xl%. Illustrations of the Anatoiny and of Shells 395 10 13 €1 14 15 25 26 27 16 17 18 28 29 30 19 20 21 31 32 11 12 22 23 ^BP^ Bp^ 24 33 34 35 PLATE 79 396 The MoUuscan Family Planorbidae PLATE 80 Shells of Planorbidae 1-3. Helisotna anceps (Menke) = Planorbis bicarinatus Sowb. and P. bicarinatus Say. From Delaware River II/2 miles above Plum Point, New Jersey. Like Say's figures. U.L, Z25738. X2. 4-6. Helisoma anceps (Menke). South Street Brook, Auburn, New York. Strongly carinated form. U.L, Z25934. X2. 7-8. Helisoma scalare (Jay). Everglades, head of Miami River, Dade Co., Florida. Baker coll., 237L X2. 9. Helisoma duryi seminole Pilsbry. Lake Eustis, Florida. Physoid shell. Baker coll., 3977. X2. 11-12. Helisoma duryi nurmale Pilsbry. Lake Pinsett, Florida. Typically planorboid shell. U.L, 41489. XIYj. 13-15. Helisoma trivolvis (Say). Braddocks Bay, near Rochester, New York. Lake Ontario. U.L, 29789. XlV->. 16-18. Helisoma campanulatum (Say). Thousand Island Park, St. Lawrence River, New York. U.L, 27112. Xli/1'. 19-21. Helisoma multivolvis (Case). Howe Lake, Marciuette Co.. Michigan. Baker coll., 1962. X2. 22-24. Planorbarius corneus (Linn.). Rhone River, France. U.L, 25740. Xli/2. IUustratio)is of the AiiatoDiy and of Shells 397 398 The Molluscan Family Planorbidae PLATE 81 Shells of Planorbidae 1. Poecilospira trochiformis (Stahl). Steinheiin, Germany. Showing extreme range of variation from short, flattened spire to long, conical spire. M.C.Z. X2. 2. Ajroplnnorbis adoivensis (Bourg.). Belgian Congo, Africa. Pilsbry and Bequaert, Bull. Amer. Mus. N.H., LIII, fig. 4, p. 118. Xfi/^. 3. Afroplanorbis sudanicus (Martens). Bahr-el-Ghazal, Africa. U.S.N. M., 215381. Pilsbry and Bequaert, op. cit., fig. 7, p. 122. Xli/4. 4. Biomphalaria smithi Preston. Upper figures, specimen from Kabare, Lake Edward, Africa; lower figures, paratypes from Lake Edward. Pilsbry and Bequaert, op. cit., fig. 6, p. 121. Xli^. 5. Paraplanorbis condoni (Hanna). Vicinity of Warner Lake, eastern Oregon. Pliocene period. Hanna, Univ. Oregon Pub., I, No. 12, plate 1, figs. 1-3. About X7. 6. Planorhijex vanvlecki (Arnold). North dome Kettleman Hills, King Co., Cali- fornia. Pliocene. PiLsbry, Proc. Acad. Nat. Sci. Phil., 86, plate 21, fig. 9, a, b, c. Reduced one-half from Pilsbry "s figure. Line indicates 1 mm. 7. Choanomphalus inaacki Ger.stfeldt. Crosse and Fischer, Jour, de Conch., XXVH, plate 4, fig. 9. 8. Choanomphnlus valvatoidcs Dybowski. Op. cit.. plate 4, fig. 8. 9. Choanomphalus schrenckii Dybowski. Op. cit., plate 4, fig. 10. Line near figures 8-10 indicates natural size. 10. Anisopsis calculus (Sandberger) . Land und Siiss.-Conch. Vorwelt, taf. 1, figs. 7, 7a. (stark vergrossert). 11. Anisopsis loryi (Coquand). Op. cit., taf. 1, figs. 28, 28a, 28b. Illustrations of the Anatomy and of Shells 399 m^ 28* ^ 26^ 10 11 PLATE 81 400 The Molluscan Family Planorhidae PLATE 82 Shells of Planorbidae 1,2. Helisoma ancejhs (Menke). Ashhmd, Virginia. Resembling Menke's figure. B999. 3-5. Helisoma anceps (Menke). Below dam at Lake Junalaska, North Carolina. B1819. 6-8. Helisoma anceps (Menke). Long Lake, Alpena, Michigan. Resembling Rackett's figm'e of Helix angulata. BIOOL 9-n. Helisoma anceps (Menke). Spring Grove, Dove Co., Alabama. Walker coll. Re- sembling Conrad's Planorbis antrosa. U.M., 6740L 12-15. Helisoma anceps (Menke). Potomac River, Fort Washington, Maryland. 14, re- sembling unicarinatum ; 15, resembling sayi. U.S.N.M., 364718. 16, 17. Helisoma anceps (Menke). Blue Creek, Coeur d'Alene Mts., Idaho. U.M., 81780. 18,19. Helisoma anceps (Menke). Portland, Oregon. Hemphill coll. C.A.S., 6875. 20-22. Helisoma anceps striatum (F. C. Baker). Bay View, Milwaukee, Wiscon.^in. From marl bed. B2851. 23-25. Helisoma anceps shellense F. C. Baker. Shell Lake, Washburn Co., Wisconsin. 23, paratype, U.I., Z19354; 24-25, type locality, U.I., Z13474. 26. Helisoma anceps (Menke). Portland, Oregon. U.C.M., 23143. 27-29. Helisoma anceps niinnesotoise (F. C. Baker). Frontenac, Minnesota. Types. B1002. 30. Helisoma anceps (Menke). Priests Lake, Bonnar Co., Idaho. U.M., 81798. 31. Helisoma anceps corrugatum (Currier). Northern part of Minnesota. B985. 32-34. Helisoma anceps sayi F. C. Baker. East Lake Okoboji, Iowa. Shimek coll., U.S.N.M., 476580. Figures are enlarged approximately two diameters lUustratious of the Auatomy and of Shells 401 mm J^ ^m ^W ^^^ ^F 10 •t ^ 11 12 13 *? "^W^ 14 15 16 17 C) 18 19 20 (• 21 22 23 24 (' /" 25 '«*■ ^ J 26 •.«>, 27 28 29 30 31 32 33 PLATE 82 34 402 The Molluscan Family Plauorbidae PLATE 83 Shells of Planorbidae 1-3. Helisoma anceps sayi F. C. Baker. Tomahawk Lake, Oneida Co., Wisconsin. Type locality. U.I., Z25736. 4-6. Helisoma anceps sayi F. C. Baker. West Lake Okoboji, Iowa. Shimek coll. Vary- ing toward anceps. U.S.N.M., 475945. 7-9. Helisoma anceps unicarinatum (Haldeman). Plum Point, Delaware River, above Riverton, New Jersey. TJ.L, Z25938. 10-12. Helisoma anceps unicarinatum (Hald.). Cherokee River, Little River Station, Alabama. U.I., Z41055. 13-15. Helisoma anceps unicarinatum (Hald.). Blackstonc River, above Courtland, West Virginia. Figure 13 resembles Haldeman's angisiomum. LT.S.N.M., 109888. 16-18. Helisoma anceps politum F. C. Baker. Honeywell Creek, Carleton Co., Ontario, Canada. F. R. Latchford coll. Holotype, fig. 16; paratypes, figs. 17, 18. U.S.N.M., 367426. 19-22. Helisoma anceps bartschi F. C. Baker. Brook at Great Falls, Virginia. Holotype, fig. 19; paratypes, figs. 20-22. U.S.N .M., 227858. 23-25. Helisoma anceps (Menke). Variety? Mouth of Yaqui River, Northwest Mexico. LT.S.N.M., 53677. 26. Helisoma anceps (Menke). Variety? Potomac River. U.S.N.M., 364718. 27-29. Helisoma anceps aroostookcnse (Pilsbiy). Woodland, Aroostook Co., Maine. Type locality. U.I., Z21015. Figures are enlarged approximately two diameters Illustrations of the Anatomy and of Shells 403 10 11 12 13 14 W 4^1 ^^ '"^lAm- jm 15 16 17 18 19 ( 20 21 22 ^% / 23 25 24 26 f ^^ 27 28 PLATE 83 29 404 The MoUuscan Family Plauorbidae PLATE 84 Shells of Plauorbidae 1. Helisoma anceps (Menke). Immature shell. XSVj. 2. Helisoma anceps percarinatum (Walker). Immature shell. XZYz- 3. Helisoma anceps portagense (F. C. Baker). Immature shell. XS^/^. 4. Helisoma anceps royalense (Walker). Immature shell. XS^/^. 5. Helisoma anceps sayi F. C. Baker. Immature shell. XS^/^. 6-8. Helisoma anceps jordanense (Winslow). Lake Charlevoix, NE of Jordan, Charle- voix Co., Michigan. Topotypes. U.M., 61589. 9. Helisoma anceps royalense (Walker). Isle Royale, Michigan. Cotype. B. Walker. B995. 10-12. Helisoma anceps rushi F. C. Baker. Toad Island, Georgian Bay, Ontario. lOholotype; 11-12 paratypes. U.I., Z25239. 13,14. HeUsoma rmceps royalense (Walker). St. Joseph Lake, Ontario. U.I., Z30853. 15-17. Helisoma anceps royalense (Walker). Bamiji Lake, Ontario. U.I., Z30844. 18-20. Helisoma eucosmius (Bartsch). Types. Bull. U.S.N.M., 33, plate 57, figs. 1-3. X4. 21. Helisoma eucosmius (Bartsch). Greenfield Pond, North Carolina. Paratype. U.S.N.M., 193890. XSV-i- 22-24. HeUsoma eucosmius vauyhani (Bartsch). Types. Bull. U.S.N.M., 33, plate 57, figs. 4-6. X4. 25. Helisoma eucosmius vaughani (Bartsch). Burke's Place, Louisiana. Paratype. U.S.N.M., 125719. XSi;.. 26-28. Helisoma anceps idahoense F. C. Baker. Pend (Jreille River, Sand Point, Idaho. Holotype. B1863. All figures are enlarged about twice excepting those otherwise listed fllusf rat ions of the Anatomy and of Shells 405 Y.-- ^ 406 The Molluscan Family Planorhidae PLATE 85 Shells of Planorbidae 1-3. Helisoma anceps porlagenac (F. C. Baker). Portage Lake, Aroostook Co., Maine. Type locality. B988. 4. Helisoma anceps portagense (F. C. Baker). Meach Lake, Quebec, Canada. B3686. 5-7. Helisoma anceps latchfordi (Pilsbry). Meach Lake, Quebec, Canada. Type locality. Collected by Latchford. U.I., Z37203. 8-10. Helisoma anceps percarinatum (Walker). Crystal Lake, Benzie Co., Michigan. Type locality. B986. 11-13. Helisoma anceps percarhuititm (Walker). Douglas Lake, Michigan. 12 ridged shell. U.I., Z26276. 14-16. Helisoma anceps cahni F. C. Baker. Big Muskallonge Lake, Vilas Co., Wis- consin. Types. U.I., Z21124. 17-19. Helisoma trivolvis (Say). Immature shells. X3. 20-24. Helisoma trivolvis (Say). Showing regular increa.se in growth of shell. LT.L, Z29134. 25-29. Helisoma trivolvis (Say). Braddock's Bay, near Rochester, New York. U.L, Z29789. 30. Helisoma trivolvis (Say). Elmira, Chemung Co., New York. U.L, Z34976. All figures excepting 17-19 are enlarged about 1% diameters Illustrations of the Anatomy and of Shells 407 ) 13 t 17 18 23 24 25 26 408 The Molluscan Family Plaiwrbidae PLATE 86 Shells of Planorbidae I. Hclisoma trivolvis (Say). Indian River, Cheboygan Co.. Michigan. (^ Planorhis. megastoma DeKay.) U.I., Z32472. 2.4. Heliaoma trivolvis (Say). Salt Fork, near Urbana, Chaniiuugn Co., Illinois. { =^ Planurbis psiudotrivolvis F. C. Baker. 2, paratype; 4, holotype). U.I., Z 11292. 3. Hclisoma trivolvis (Say). Salt Fork, near Urbana, Illinois. {^= Planorbis pseudo- trivolvis F. C. Baker. Type locality.) B930. 5-8. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. Type locality. \j.l., Z30538. 9,10,1^- ficlisotna trivolvis intcrtextum (Sowerby). Manatee Rivor, Florida. U.I., Z32367. II, 12, 15. Hclisoma trivolvis intcrtextum (Sowb.). Shoal Creek, Alabama. U.I.. Z32365. 14. Hclisoma trivolvis intertcxtum (Sowb.). Manatee River, Florida. B1085. 16. Hclisoma trivolvis chautauquensc F. C. Baker. Chautauciiia Assembly, Chautau- ciua Lake, New York. Type locality. U.I., Z27842. 17. Hclisoma trivolvis chautaucptoisc F. C. Baker. Chavitauqua Lake, New York. Holotype. U.L, Z23780. 18. 19. Helisoma trivolvis chautauqucnse F. C. Baker. Chautauqua Lake, New York. Paratypes. U.L, Z23780. 20. Hclisoma trivolvis (Say). Enlargement of whorls on base. B3914. X7. 21. Hclisoma trivolvis (Say). {^ Planorbis pseudotrivolvis F. C. Baker). Enlargement of whorls on base. B3915. X7. 22. Hclisoma trivolvis lentum (Say). Enlargement of whorls on base. B3916. X7. 23. Helisoma trivolvis intcrtextum (Sowb.). F.nlargement of whorls on base. B3917. X7. All figures, excepting those indicated otherwise, are enlarged about I73 diameters Illustrations oj the Anatomy and of Shells 409 410 The MoUuscan Family Plmiorhidae PLATE 87 Shells of Planorbidae 1-4. HeUsoma trivoJvis fallax (Haldeman). Milton Mills, Milton, Massachusetts. U.I., Z41108. 5-7. HcUsotna trivolvis fallax (Haldeman). Green Lodge, Xeponset. Massachusetts. B904. 8,9. Hclisoma trivolvis fallax (Haldeman). Fresh Pond, Cambridge, Massachusetts. U.S.N.M., 33657L 10. Helisomn trivolvis fallax (Haldeman). Port Elizabeth, Maine. U.S.X.M., 26449. 11-15. HeUsoma trivolvis marshnlli F. C. Baker. Washington, D.C. 13, holotype; 11-12, paratypes; 14-15, immature. U.S.N .M., 124989. 16. HeUsoma trivolvis marshalli F. C. Baker. New Jersey. LT.S.N.M., 504153. 17-20. HeUsoma trivolvis holstonense F. C. Baker. Holston River, Smith Co., Virginia. 17, holotype; 18-20, paratypes. U.I., Z41443. 21. HeUsoma trivolvis lentum (Say). New Orleans, Louisiana. Immature. Aquarium specimen. B3918. 22. Hclisoma trivolvis holstonense F. C. Baker. Holston River, Virginia. Immature. U.I., Z41444. 23,24. HeUsoma trivolvis holstonense F. C. Baker. Holston River, Virginia. Variation in color. U.I., Z41444. All figiu'es are enlarged about two diameters IUustratio)hs of the Aiuitony and of Shells 411 r\ 10 11 12 13 14 15 16 17 ^ 18 19 20 6i i» 21 22 23 24 PLATE 87 412 The Molluscan Family Planorhidae PLATP: 88 Shells of Planorbidae 1,2. Helisoma trivolvis trivolvis (Say). Presqiie Isle, Michigan. Transition form toward macrostomum. U.I., Z26268. 3. Helisoma trivolvis trivolvis (Say). Winnebago Lake, near Oshkosh, Wisconsin. Large form, but typical. U.I., Z1279L 4-6. Helisoma trivolvis macrostommn (Whiteave.s). Mile End Gate, near Montreal, Canada. National Museum of Canada. 4, lectotype, 3869; 5-6, paratypes, B3870. 7. H rlisoma trivolvis macrostomum (Whiteaves). Bayfield, Wisconsin. In beach pool. U.I., Z13677a. 8-10. Helisoma pilsbryi (F. C. Baker). Tomahawk Lake, Oneida County, Wisconsin. Type locality. B843. 11-13. Helisoma pilsbryi injracarinatnm F. C. Baker. Rideau River, near Ottawa, Canada. B3715. 14, 15. Helisoma pilsbryi infracarinatum F. C. Baker. Basswood River Rapids, Rainy River District, Ontario. 14, holotype, U.I., Z32361; 15, paratype, B2986. 16. Helisoma pilsbryi infracarit^atum F. C. Baker. Basswood Lake, Ontario, Canada. U.I., Z41268. All figures enlarged about 1V> diameters lUustrations of the Auatomij and of Shells 413 414 The Molluscan Family Plwwrhidae PLATE 89 Shells of Planorbidae 1-4. Helisoma trivolvis hntum (Say). Austin, Texas. Figure 3 varies toward hiter- textum. U.S.N.M., 252256. 5,6. Helisoma trivolvis intertcxtum (Sowb.). Fort Smith, Arkansas. Variation toward lentum (fig. 6). U.S.N.M., 120965. 7. Helisoma trivolvis intertextum (Sowb.). South CaroHna? Binney's fig. 179 of Pln- norbis glabratus (not of Say). U.S.N.M., 29219. 8. Helisoma trivolvis intertextum (Sowb.). Leon, Texas. U.S.N .M., 28210. 9,10. Helisoma trivolvis reticulatum (Dall) {^intertextum Say). Salt Lake, Hils- borough Co., Florida. Types. U.S.N.M., 75421. 11. Helisoma truncatum (Miles). Saginaw Bay, Michigan. Type. Binney's fig. 202. U.S.N.M., 9010. 12. Pknwrbis bellus Lea (^= Helisoma trivolvis lentum (Say) ). Type. Tennessee. Lea Coll., U.S.X.M., 121178. 13-17. Helisoma kennicotti F. C. Baker. Lake Isle la Crosse, English River, Canada. 15, holotype; 16, 17, paratypes; 13, 14, immature. U.S.N.M., 29231 (old 9272). 18. Helisoma subcrenatum (Cpr.). Reservoir near Flowcree, Montana. B3792. 19. Helisoma subcrenatum (Cpr.). Wainwright Park, Alberta. U.I., Z34689. 20. Helisoma subcrenatum {C]n\). Fort Yukon, Alaska. U.S.N .M., 218908. 21. Helisoma subcrenatum disjecturn (Cooper). Boise, Idaho. U.I., Z36335. 22. Helisoma subcrenatum plexatum (Ing.). Sagnache, Colorado. U.S.N.M., 535328. 23. Helisoma occidentale (Cooper). Klamath Falls, (3regon. U.S.N.M., 219750. 24. Helisoma occidentale (Cooper). Tule Lake, California. U.S.N.M., 160839a. 25. Helisoma ammon (Gould). Daggett, California. U.S.N.M., 349083. 26. Helisoma amnion (Gould). Spring Valley, San Mateo Co., California. U.M., 84105. 27. Helisoma ammon (Gould). Clear Lake, California. U.M., 81743. 28,29. Helisoma trivolvis (Say). Aquarium specimens raised by Dr. E. G. Berry. Note resemblance to Helisoma duryi seminole. B3796. Figures 18-29, immature. All figures are enlarged a trifle less than two diameters lUustratious of the Anatomy and of Shells 415 PLATE 89 416 The Molluscan Family Plauorbidae PLATE 90 Shells of Planorbidae 1-4. Helisoma (runcatum (Miles). Saginaw Bay, Michigan. Type locality. U.I., Z32515. 5-8. Helisoma truncatuui (Miles). Spirit Lake, Iowa. U.S.N.M., 476566. 9. Helisoma truncatum (Miles). Spirit Lake, Iowa. U.S.N.M., 505847. 10. Heluoma truncatum (Miles). Sturgeon Bay, Door Co., Wisconsin. U.I., Z18455. 11,12. Helisoma truncatum (Miles). Winnebago Lake, Wisconsin. U.I., Z12805. 13-15. Helisoma subcrenatum disjectum (Cooper). Tuolumne, California. B1090. 16-18. Helisoma subcrenatum disjectum (Coojier). Boise, Idaho. LT.L, Z36335. 19-21. Helisoma subcrenatum horni (Tryon). Paul Lake, British Columbia. B3148. 22-24. Helisoma subcrenatum variety? Quamichan Lake, British Cohmibia. B1973. All figures are enlarged a little less than two diameters Illustratio)is of the Anatonnj and of Shells 417 / y. c^^^j^ 10 11 12 13 V ^ 16 19 14 ( 17 20 15 22 21 JjS 418 The Molluscan Family Planorbidae PLATE 91 Shells of Planorbidae 1-4. Helisoma winslowi (F. C. Baker). Little Arbor Vitae Lake, Vilas Co., Wisconsin. Paratypes. Figure 4, immature. X 31/1-. U.L, Z18637, Z19398. 5. Helisoma pilsbryi (F. C. Baker). Chetek Lake, Barron Co., Wisconsin. B. 6-8. Helisoma pilsbryi preblei F. C. Baker. Knee Lake, Manitoba. Figure 6, holotype; 7-8, paratypes. U.S.N.M., 180279. 9-12. Helisoma subcrenatum (Carpenter). Idaho. Shimek Coll., U.S.N.M., 504310. 13. Helisoma subcrenatum (Cpr.). Third Vermilion Lake, below warm sulphur cave, Alberta. Pathologic specimen. U.S.N.M., 272105. 14. Helisoma subcrenatum (Cpr.). Lake La Hoche, British Columbia. U.S.N.M., 43346. 15. Helisoma subcrenatum (Cpr.). Locomotive Springs, Kelton, Utah. U.S.N.M., 308926. 16.18,19. Helisoma subcrenatum variety? Utah Lake, 2 miles south of Lehi, Utah. B1894. 17. Helisoma subcrenatum variety? Same locality as above. Variation toward subcre- natum. B1894. All figures, excepting 4, are enlarged about V/j diameters lUustrations of the Anatouiy and of Shells 419 8 11 14 17 C^^« 10 :.^lU > 12 15 / 18 PLATE 91 19 420 The MoUuscan Family Plaiwrbidae PLATE 92 Shells of Planorbidae 1,2. Helisoma subcrenatum (Cpr.). Newton, Utah. B3046. 3. Helisoma suhcrenatum (Cpr.). Stewart River, Yukon Dist., Alaska. U.S.N .M., 180281. 4. Helisoma subcrenatum (Cpr.). Cleary, Alaska. Fos.sil pits. U.S.N .M., 381941. 5. Helisoma subcrenatum (Cpr.). Great Slave Lake. Kennicott Coll., U.S.N.M., 9275. 6,7. Helisoma subcrenatum (Cpr.). Wainwright Park, Alberta. B3919. 8-10. Helisoma subcrenatum (Cpr.). Fort Simpson, Mackenzie District, Canada. Kenni- cott Coll., U.S.N.M., 28378. 11,12. Helisoma subcrenatum (Cpr.). Creek one mile west of Devon, Montana. Im- matm-e. B3793. 13-15. Helisoma subcrenatum horni (Tryon). Fort Yukon, Alaska. U.S.N.M., 218908. 16. Helisoma subcrenatum horni (Tryon). Dall Ri\er, Alaska. Vaiying toward sub- crenatum. U.S.N.M., 180280. 17-22. Helisoma subcrenatum plexatum (IngersoU). St. Mary Lake, Mineral Co., Colo- rado. Figure 17, lectotype, U.S.N .M., 420210; figs. 18-22, paratypes. U.S.N .M., 125130. 23. Helisoma subcrenatum plexaium (Lig.). Sagnache, Colorado. Lnmature. L^.S.N.M., 535328. All figures are enlarged about IVj, diameters Illustrations of the Anatomy and of Shells 421 422 The Molluscan Family Planorhidae PLATE 93 Shells of Planorbidae 1-3. Helisoma subcrenatum plexatum (Ing.). Great Falls. Montana. U.S.X.M., 183037. 4. Helisoma occidentale (Cooper). Tule Lake, California. L'.S.X.M., 160S39a. 5. Helisoma occidentale (Coojier). "Wa-^hington Territory.' Binney".s fig. 193. U.S.X.M.. 9120. 6. Helisoma occidentale (Cooper). Klamath Falls. Oregon. U.S.X.M.. 219750. 7,8. Helisoma occidentale (Cooper). Upper Klamath Lake, .south boundary of reserva- tion, Oregon. L'.M., 62741. 9.10. Helisoma occidentale (Cooper). Lower end Upi)er Klamath Lake, Oregon. B3246. 11.12. Helisoma occidentale (Cooper). Slough at Wacos Bay, Klamath Lake, Oregon. B3069. 13.14. Helisoma occidentcde (Cooper). Uiqier Klamath Lake. Oregon. B3011. 15. Helisoma occidentale (Cooper). Upper Klamath Lake, south boundary of reserva- tion. U.M., 62741. 16. Helisoma occidentale depression F. C. Baker. Lower Klamath Lake, Oregon. Holotype. B3239. 17, 18. Helisovia occidentale depressum F. C. Baker. Lower Klamath Lake, Oregon. Paratypes. B3240. 19,20. Helisoma binneyi (Tr3'on). Portland, Oregon. Stanford Univ., B3220. 21,22. Helisoma binneyi (Tryon). Lake Whatcom, Washington. B853. 23-26. Helisoma binneyi (Tryon). Holders Lake, Xanaimo, British Cohunbia. U.AL. 81750. All figures are enlarged about l^-'> diameters lUustrations of the Aiiatomij and of Shells 423 424 The Molluscan Faniilij Plaiwrbidae PLATE 94 Shells of Planorbidae 1-5. Helisoma hinneyi randolphi F. C. Baker. Seattle, Washington. Figure 1, holotype; 2-4, parat.ypes; 5, immature. U.S.X.M., 504360. 6-8. Helisoma hinneyi randolphi F. C. Baker. Green Lake, Seattle, Washington. About half grown. U.S.N.M., 474779. 9-11. Helisoma hinneyi (Tryon). Astoria, Oregon. B1888. 12,13. Helisoma bi)tiieyi (Tryon). Portland, Oregon. Immature. LT.L, Z35295. 14. Helisoma antmon (Gould). Spring Valley, San Mateo Co., California. Immature. U.M., 84105. 15. Helisoma ammoii (Gould). Near Cerritos, Los Angeles Co., California. Immature. U.S.N.M., 174051. 16. Helisoma hinneyi (Tryon). Astoria, Oregon. Back view of shell. U.I., Z18459. 17. Helisoma ammon (Gould). Monterey, Monterey Co., California. Back view of •shell. U.M., 81746. 18. Helisoma hinneyi (Tryon). Oregon. Tyi)e. Gould's figure of Planorhis corpnlentum Say, U.S. Ex. Exped., plate 8, fig. 130. U.S.X.M., 5530. 19. Hilisotna hinneyi (Tryon). Columbia River, Oregon. Binney's fig. 191 of Planorhis corpulentum Say. U.S.N.M., 8119. 20.21. Helisoma ammon (Gould). Hollister, San Benito Co., California. U.M., 81748. 22-24. Helisoma ammon (Gould). Stockton, San Joachin Co., California. B3246. 25,26. Helisoma a)nmon (Gould). San Joachin River, California. I'.M., 81749. 27. Helisoma amnion (Gould). San Diego, California. TT.M., 35676. 28. Helisoma am>no)i (Gould). Stockton, San Joachin Co., California. Immature. U.M., 81571. All figures are enlarged about II/2 diameters Illustrations of the Anatomy and of Shells 425 426 The Molluscan Family Planorbidae PLATE 95 Shells of Planorbidae 1-5. Helisoma amnion (Gould). Mountain Lake near San Francisco, California. Immature form. B3288. 6-9. Helisoma amnion (Gould). Clear Lake, California. Stages of growth. U.M., 81743. 10,11. Helisoma avimon (Gould). Clear Lake, California. LT.M., 81752. 12-14. Helisoma ammon (Gould). Watsonville, Santa Cruz Co., California. LT.M., 81747. 15. Helisoma ammon (Gould). Kern Lake, Tulare Co., California. Cooper Coll., B9124. 16. Helisoma ammon (Gould). Point Happy, Indio, California. U.I., Z35624. 17-19. Helisoma traskii (Lea). Bakersfield, Kern Co., California. Immature. U.M., 81754. 20,21. Helisoma traskii (Lea). Kern Lake, Tulare Co., California. Type of Lea, figured by Binney, 188. Lea Coll., U.S.N.M., 121000. 22. Helisoma traskii (Lea). California? U.S.N.M., 47616. . 23-25. Helisoma traskii (Lea). Bucna Vista Canal, draining Buena Vista Lake, which drained Kern Lake, California. More depres.sed than Lea's type. B3066. All figures are enlarged about P/i' diameters Illustrations oj the Anatomy and oj Shells 427 Obilito 1 6 428 The Molluscan Family Planorbidae PLATE 96 Shells of Planorbidae 1-3. Helisoma oregoneiise (Tiyon). Pueblo Valley on boundary of Oregon, sixty miles west of east boundary. Type locality. B1096. 4,5. Helisoma oregonense (Tryon). Nevada. Stearns Coll. U.M., 35679. 6-8. Helisoma oregonense (Tryon). Sixteen miles northwest of Gerbach, Nevada. M.C.Z., 92410. 9-12. Helisoma oregonense (Tryon). Variation. Tooele Co., Utah, in salt spring. B3920. 13-17. Helisoma subcrenatum perdisjectum F. C. Baker. Yellowstone Lake, Wyoming. Figure 13, holotype; 14-17, paratypes. U.S.N.M., 30207a. 18-22. Helisoma anceps anticostianum F. C. Baker. English Bay, Anticosti Island. Fig. 18, holotyi)e; 19-22, paratypes. M.C.Z., 48285. 23-30. Helisoma anceps (Menke). Chevanus Pond, north of Knoxville, Tennessee. Figures 24, 25, 29, normal anceps; figs. 26, 27, 28. 30, the angistomus form of Haldeman; fig. 23, immature. M.C.Z., 46502. 31-34. Helisoma magnificum (Pilsbry). Greenfield Pond, near Wilmington, North Carolina. Typo locality. Bartsch's figs. Proc. U. S. Nat. Mus., 33, plate 57, figs. 7-9. U.S.N.M., 193321. Figures 1-30 are enlarged about two diameters; figs. 31-34 are about natural size. Illustrations of the Anatomy and of Shells 429 te#^ ""9 CP 11 12 10 13 14 15 ^ 16 17 1- \ ^r3 18 1^ 21 22 23 24 25 *( 26 27 28 '-•< ^.*- 29 30 31 .^ 32 \^ 33 PLATE 96 M^V 34 430 The Molluscan Family Planorbidae PLATE 97 Shells of Planorbidae 1-4. Helisoma tenue (Philippi). Platpa near City of Mexico, Mexico. Tj'pe locality. U.S.N.M., 160175. 5. Helisorna tenue (Philippi). Laguna de Tamos, near Tampico. Vera Cruz, Mexico. U.S.N.M., 467437. 6. Helisoma tenue (Philippi). Toluca, Mexico. U.S.N .M., 185942. 7,8. Helisoma tenue (Philippi). Lake Texcoco, near City of Mexico, Mexico. M.C.Z. 9. Helisoma tenue (Philippi). Vera Cruz. Strebel Coll. U.S.N.M., 10585. 10. Helisoma tenue (Philijipi). Sources of Rio Lerma, Valley of Toluca, Mexico. U.S.N.M., 467433. 11. Helisoma tenue (Philippi). Orizaba, Mexico. U.S.X.M., 22009. 12. Helisoma tenue bourcardi (C. and F.). City of Mexico, Mexico. U.S.N.M., 8506. 13-17. Helisoma tenue bourcardi (C. and F.). City of Mexico, Mexico. U.S.N.M., 26453. 18-25. Helisoma tenue craggeratum (von Martens). Lake Patzcuaro, State of Michoa- can, Mexico. Type locality. U.S.N.M., 467462. 26-28. Helisoma tennc applanatum (von Marten.s). Lanos River, Chichuachua, Mexico. U.S.N.M., 16252. All figures are enlarged about P/o diameters lUustratiotis of the Anatotny and of Shells 431 PLATE 97 432 The Molluscan Family Planorhidae PLATE 98 Shells of Planorbidae 1. Helisoma tenue applanatam (von Martens). Orizaba, Mexico. Strebel Coll. U.S.N.M., 10538. 2-6. Helisoma tenue applanatum (von Martens). Yaqui River, near Cimlad Obregon, Sonora, Mexico. U.S.N.M., 467429. 7,8. Helisoma tenue applanatuni (von Martens). Mazatlan, Mexico. Lea Coll. U.S.N.M., 121192. 9-13. Helisoma tenue sinuosum (Bonnet). Santa Cruz River, Tucson, Arizona. In stream bed. U.S.N.M., 130237. 14-. Helisoma tenue sinuosum (Bonnet). Soroyta Creek, Sonora, Mexico. U.S.N. M., 130229. 15. Helisoma tenue sinuosum (Bonnet). Albuquerque, New Mexico. 5000 ft. altitude. U.S.N.M., 134552. 16, 17. Helisoma tenue caUforniense F. C. Baker. Santa Cruz, California. U.S.N.M., 47571. 18. Helisoma tenue calijorniensc F. C. Baker. Santa Cruz, California. U.S.N. M., 47572. 19-21. Helisoma tenue calijorniense F. C. Baker. Crystal Creek, San Jose, California. U.S.N.M., 32111. 22. Helisoma tenue ealijorniensc F. C. Baker. Santa Cruz Mts., 4 miles from Los Gatos, California. U.S.N.M., 75437. 23,24. Helisoma tenue calijorniense F. C. Baker. Guadeloupe Creek, San Jose, Cali- fornia. Paratypes. B3262. 25. Helisoma tenue sinuosum (Bonnet). Rio Grande. El Paso, Texas. Immature. U.S.N.M., 130239. 26. Helisoma tenue calijorniense F. C. Baker. Bixby, Los Angeles Co., California. Immature. B3227. Figures 25 and 26 show differences in spire whorls and sculpture of the two ^'arieties All figures are enlarged about V/^. diameters Illustrations of the Anatomy and of Shells 433 434 The Molluscan Family Planorbidae PLATE 99 Shells of Planorbidae 1. Hclisoma ienue applanatutn (\on Martens). Near Vallecitos, Lower California. Im- mature. U.S.N.M., 162654. 2,3. Hclifioma tome applanatum (von Martens). Yaqui River, near Ciudad Obregon, Mexico. Immature. U.S.N.M., 467429. 4-8. Hvlixoma tenue sinuosiini (Bonnet). Santa Cruz River, Tucson, Arizona. Imma- ture. U.S.N.M., 130237. 9,10. Hclisoma tenue sinuosum (Bonnet). Rio Grande, El Paso, Texas. Immature. U.S.N.M., 130239. 11-15. Helisoma tenue calif orniense F. C. Baker. Bixby, Los Angeles Co., California. Immature. U.S.N.M., 174048. 16-19. Hclisoma tenue strebclianum (F. and C). Penasco, 5 miles north of San Luis Potosi, Mexico. Immature. LT.S.N.M., 251815. 20-24. Hclisoma caribacum guatcmalcnsc (Clessin). Reservoirs 4 miles north of Guatemala City, Guatemala. U.M., 83490. 25. Hclisoma tenue strebelianum (F. and C). Tamaulipus, Mexico. LT.S.N.M., 109916. 26. Hclisoma tenue strebelia7ium (F. and C). Coy River, San Luis Potosi, Mexico. B3921. 27-30. Hclisoma tenue strcbelianuia (F. and C). Alta Mira, Tamaulijius, Mexico. U.S.N.M., 251807. 31. Hclisoma caribacum (Orb.). Naranjo, (Juatemala. Varying toward Hclisoma cari- bacum guatcmalense. LT.M., 83487. 32-36. Helisoma caribaeu}7i guatemalense (Clessin). Nicaragua. U.M., 83485. All figures are enlarged about 1^/4 diameters Illustrations oj the Anatomy and of Shells 435 436 The Molluscan Family Plauorbidae PLATE 100 Shells of Planorbidae 1,2,5. Ilclisoma caribaeum (Orb.). Cuba. I'.M., 83491. 3.4. Helisoma caribaeum (Orb.). Punta d? hi Junta, Cuba. U.S.X.M.. 11204. 6-10. Helisoma caribaeum (Orb.). Panama. U.M., 83492. 11-13. Helisoma caribaeum (Orb.). Somorrostro, Havana, Cuba. B3075. 14-17. Helisoma caribaeum (Orb.). Vera Cruz, Mexico. U.S.X.M., 210882. 18-20. Helisoma unjldii saluini (Tristram). Guatemala. U.S.X.M., 121023. 21-24. Helisoma ivijidii (Tristram). San Carlos, Nicaragua. U.S.N. M., 354295. 25-27. Helisoma unjldii (Tristram). Lake Olomega, San Salvador. U.S.N. M., 360392. 28. Helisoma wyldii (Tristram). Lake Metapan, San Salvador. U.S.N.M., 360391. 29,30. Helisoma wyldii (Tristram). Lake Guija, San Salvador. U.S.N.M., 360390. 31. Helisoma lumens (Cpr.). Mazatlan, Mexico. U.S.N.M., 46967. 32,33. Helisomn tumens (Cpr.). Mazatlan, Mexico. U.S.N. M., 47517. 34-37. Helisoma tumens (Cpr.). Mazatlan. Mexico. B2284. All figures are enlarged about \y> diameters Illustrations of the Anatomy and of Shells 437 18 27 PLATE 100 438 The Molluscan Family Planorhidae PLATE 101 Shells of Planorbidae 1. Helisoma jovealc (Menke). Jamaica. U.S.N.M., 74762. 2. Helisoma jovealc (Menke). Jamaica. U.S.N.M., 90479. 3,4,6. Helisoma foveale (Menke). Kingston, Jamaica. U.S.N.M., 454058. 5. Helisoma foveale (Menke). Kingston, Jamaica. U.S.N. M., 74762. 7. Helisoma magnificum (Pilsbry). Young, bom in capti\-ity. Parent from type locality. U.S.N.M. 8,9. Helisoma costaricense (Preston). Catalina, Guanacaste, Costa Rica. Cotype. B2132. 10. Helisoma costaricense (Preston). Catalina, Guanacaste, Costa Rica. Figured type. U.S.N.M., 202522. 11.12. Helisoma anceps idahoense F. C. Baker. Foot of Elbow or Lindbergh Lake, Mission Mts., Montana. M.C.Z. 13. Helisoma subcremttum variety? Utah Lake, Utah. U.S.N.M., 29332. 14. Helisoma suhcrcnatum. (Cpr.). Oregon. From Nuttall in Lea Coll. U.S.N.M., 120986. 15. Helisoma caribacum (Orb.). Cuba. To show rounded inner whorls. U.M., 83491. X6. 16. Helisoma teniic applanatum (von Martens). To show flat inner whorls. U.S.N.M., 10538. All figures, excepting 15 and 16, are enlarged about U/2 diameters Illustrations oj the Anatomy and of Shells 439 •■»*.. -.,^ M Ul^ 15 16 PLATE 101 440 The Molluscan Family Planorbidae PLATE 102 Shells of Planorbidae 1. Hdisoma tenue chapaleme (Pilsbry). Proc. Acad. Sci. Phil., 1920, i>. 193, fig. 1. En- larged. 2. Hclisoma contrerasi (Pilsbiy). Proc. Acad. Sci. Phil., 1920, \k 193, fig. 2. Enlarged. 3,4. Helisoma contrerasi (Pilsbry). Lake Chaiiala, near Guadalajara, Mexico. U.S.N.M., 225863. 5-10. Hclimma ten tie ehapalense (Pilsbry). Oaxaca, Mexico. U.S.N.M., 117952. 11,12. Helisoma seal are (Jay). Caloosatchee Pliocene formation, Florida. B1106. 13,14. Helisoma scalare (Jay). Lake Griffin, near Leesburg, Florida. B1438. 15-18. Helisoma scalare (Jay). Head of Miami River, Everglades, Dade Co., Florida. B2969. 19,20. Helisoma scalare (Jay). Everglades, Florida. B3002. 21. Helisoma duryi seminole Pilsbry. Everglades, Florida. B2962. 22,23. Helisoma duryi seminole Pilsbry. Sumter Co., Florida. B2965. All figures, excepting 1 and 2. are enlarged about two diameters Illustrations of the Anatomy and of Shells 441 £ #^% 442 The Molluscan Family Plauorbidae PLATE 103 Shells of Planorbidae 1,2. Helisoma duryi soninole Pilsbry. Everglades, Florida. B2962. 3-5,8,9. Helisoma duryi scminole Pilsbry. Lake Eustis, Lake Co., Florida. Paratypes. B2960. 6,7. Helisoma duryi semiiiole Pilsbry. Lake Eustis, Lake Co., Florida. U.L, Z32368. 10, 11. Helisoma duryi seminole Pilsbry. Okechobee Lake, near More Haven, Florida. M.C.Z., 43311. 12. Helisoma duryi seminole Pilsbry. Lake Apopka, Florida. M.C.Z., 71599. 13. Helisoma duryi seminole Pilsbry. Lake Apopka, Florida. M.C.Z., 71598. 14-18. Helisoma duryi semiiiole Pilsbry. Survey, Lee Co., Florida. M.C.Z., 68236. 19. Helisoma duryi seminole Pilsbry. Sumter Co., Florida. U.L, Z32364. 20-30. Helisoma duryi (Wetherby). Near West Palm Beach, Florida. M.C.Z., 82856. 31. Helisoma duryi (Wetherby). Miami, Florida. L'.S.N.M.. 153412. These figures show the great variation in form of spire and shape of shell of the dnryi complex, especially the form seminole. All figures are enlarged about P/i; diameters Ilhisf rations of the Anatomy and of Shells 443 V K J^*' \^- #^* 10 444 The Molluscau Family Planorbidae PLATE 104 Shells of Planorbidae 1-3. Heliscmici duryi (Wetherby). Kissimmee River, Florida. \'ariation toward variety normale. U.S.N.M., 168921. 4-7. HcUsoma duryi (Wetherby). Near West Palm Beach, Palm Beach Co., Florida. Variation toward variety normale. M.C.Z., 45103. 8-16. Helisoma duryi normale Pilsbry. One mile north of Oil well, Pinecrest, Ever- glades, Florida. U.I., Z34637. 17. Helisoma duryi normale Pilsbry. Canal west of Boynton, Palm Beach Co., Florida. Malleated base. M.C.Z., 76659. 18-22. Helisoma duryi normale Pilsbry. Magnolia, Florida. M.C.Z., 87505. All figures are enlarged about 1V> diameters lUustratioiis of the Anatomy and of Shells 445 15 (^ 16 10 11 17 C r^ 12 18 19 13 PLATE 104 446 The Molluscan Family Plauorhidae PLATE 105 Shells of Planorbidac 1-3. Helisoma duryi nurtnale Pilsbry. Everglades 40 miles from Ft. Meyers, Florida. M.C.Z., 71020. 4-8. Helisoma duryi intercalarc (Pil.^bry). East shore Lake Okeechobee, Palm Beach Co., Florida. M.C.Z. 9. Helisoma duryi intercalarc (Pilsbry). Beecher Spring, Wakulhi, Wakullii Co., Florida. U.S.N.M., 153079. 10.11. Helisoma duryi iuterccdare (Pilsbry). Lake Je.ssup, Florida. U.S.X.M., 167040. 12,13. Helisoma duryi intercalarc form alternalum Pilsbry. Blue Creek, Lake Co., Florida. Type locality. M.C.Z., 83729. 14-16. Helisoma duryi eudiscus Pilsbry. Head of Miami River, near Miami, Dade Co., Florida. Paratypes. B3074. 17-19. Helisoma duryi eudiscus Pilsbry. Silver Springs, Marion Co., Florida. Varying toward intercalare. B3073. 20-27. Helisoma duryi prcglabratum (Marshall). Canal, Palm Beach Co., Florida. Type locality. M.C.Z. , 46572. AH figures are enlarged about lY^ diameters Illustrations of the Anatomy and of Shells 447 448 The Molluscan Family Plauorhidae PLATE 106 Shells of Planorbidae 1-3. Helisoma duryi seminole Pilsbiy. Florida. U.S.N.M., 99301. 4. Helisoma connnti Dull. Calocsahatchee River. Florida. U.I., Z40570. 5-7. Helisoma conanti Dall. Caloosahatchee River, Florida. B1107. 8. Helisoma disstoni (Dall). Vero, St. Lucia Co., Florida. U.S.X.M., 331971. 9-11. Helisoma species? Asecibo, Puerto Rico. U.S.X.M., 535394. 12-15. Helisoma disstoni (Dall). Canal, Palm Beach Co., Florida. M.C.Z., 99182. 16. Helisoma corpulentum midticostatum F. C. Baker. Lake Kahnipiminanikok, Ontario, Canada. Young. U.I., Z32628. 17. Helisoma corpulentum (Say). Lac la Croix, Ontaria, Canada. Youno;. U.L, Z32626. 18. Helisoma whiteavesi F. C. Baker. Lac des Mille Lacs, Ontario, Canada. Holotype. U.L, Z32311. 19,20. Helisoma ivhiteavesi F. C. Baker. Lac des Mille Lacs, Ontario, Canada. Para- types. U.L, Z32312. 21. Helisoma ivhiteavesi F. C. Baker. Lac des Mille Lacs, Ontario, Canada. Paratype, Immature. U.L, Z32313. 22. Helisoma corpulentum (Say). Kettle Fall.'^, Rainy Ri\er District. Ontario, Canada. Began as a corpulentum and on last whorl changed form of shell toward that of multicostatuyn. U.S.N.M., 361737. All figures are enlarged about P,-'> diameters Illustrations of the Anatomy and of Shells 449 € ^^ 12 15 450 The MoUuscan Family Plauorbidae PLATE 107 Shells of Planorbidae 1-4. Hclisomo corpuloition (Say). Lac la Croix, Ontario. Canada. U.I., Z32296. 5. Helisoma corpulent lun (Say). Rainy Lake, Ontario, Canada. A type locality. BUOl. 6. Helisoma corpulentum (Say). Rabbit Point, west of Sabaskong Bay, Lake of the Woods, Canada. A type locality. Resembles Say's figure. U.L, Z41286. 7. Helisoma cor]>uletdum (Say). Lac la Croix, Ontario, Canada. U.L, Z32626. 8. Helisoma corpulentum vennilioncnse F. C. Baker. Vermilion Lake, St. Louis Co., Minnesota. Holotype. B3021. 9,10. Helisoma coripulentum vermilionense F. C. Baker. Vermilion Lake, Minnesota. Paratypes. B3014. 11. Helisovia corpulentuvi vermilionense F. C. Baker. Vermilion Lake, Minnesota. Paratype, immature. U.L, Z32518. 12. Helisoma corpulenlum multicostatiim F. C. Baker. Lake Kahnipiminanikok, Ontario, Canada. Holotype. U.L, Z32308. 13. Helisoma corpulenlum (Say). Lac la Croix, Ontario, Canada. Young. U.L, Z32626. 14. Helisoma corpulentuni vermilionense F. C. Baker. Vermilion Lake, Minnesota. Young. U.L, Z32627. 15. Helisoma whiteavesi F. C. Baker. Lac des Mille Lacs, Canada. Young. U.L, Z32312. 16-18. Helisoma corpulentum multicostatum F. C. Baker. Kahnipiminanikok Lake, Ontario, Canada. Paratypes. U.L, Z32307. 19. Helisoma corpulentum multicostatum F. C. Baker. Knife Lake, Minnesota. U.L, Z29828. 20. Helisoma corpulentum multicostatum F. C. Baker. Bemidji Lake, Beltrami Co., Minnesota. U.L, Z32475. 21. Helisoma corpulentum multicostatum F. C. Baker. Kahnipiminanikok Lake, On- tario, Canada. Lnmature. U.L, Z32628. All figures are enlarged about P/^ diameters niusf rations of the Anntomy and of Shellt 451 5 r ^W^^is^f^^ 452 The Molluscan Family Plauorhidae PLATE 108 Shells of Planorbidae 1-6. Helhoma cainpanulatum (Say). Cayuga Lake, New York. Type locality. U.S.N. M., 212700. 7-9. Helkoma campanulatum (Say). North end Cayuga Lake, New York. Probable type locality. B1043. \0,n. Hdkoma campanulatum (Say). Ottawa, Ontario, Canada. U.S.N.M., 120985. 12-14. Hdisoma campanulatum (Say). North end Canandaigua Lake, New York. B3859. 15-17. Hdisoma campanulatum (Say). Crooked Lake, Odcn, Michigan. Variation in size. U.L, Z19877. 18. Hdisoma campanulatum fcrrmi F. C. Baker. Marl Lake, Fair Grounds, Joliet, Will Co., IlHnois. Holotype. U.L, P1068a. 19. Hdisoma campanulatum ferrissi F. C. Baker. Same locality as above. Paratype. U.L, Pl068b. 20-25. Hdisoma campanulatum ferrissi F. C. Baker. Same locality as above. Para- types. U.L, P1068. 26-28. Hdisoma campanulatum jcrrissi F. C. Baker. White Lake, Oakland Co., Michi- gan. U.L, Z20908. 29-31. Hdisoma campanulatum ferrissi F. C. Baker. Literior Charity Lsland, Michigan. B3860. 32-34. Hdisoma campanulatum ferrissi F. C. Baker. Lermond, Bonne Bay, Newfound- land. B3858. All figures are enlarged about two diameters Illustrations of the Anatomy and of Shells 453 % 32 33 PLATE 108 34 454 The Molluscan Family Planorhidae PLATE 109 Shells of Planorbidae 1-6. Helisoma campanulatum (Say). Pine Island Lake, Kent Co., Michigan. Exagger- ated campanulate lip. B3922. 7. Helisoma campanulatum wisconsinense (Winslow). Little Arbor Vitae Lake, Vilas Co., Wisconsin. Type locality. U.I.. Z18421. 8. Helisoma campanulatum wisconsinense (Winslow). Tomahawk Lake, Wisconsin. B1718. 9. Helisoma campanulatum wisconsinense (Winslow). Tomahawk Lake, Wiscon.sin. B1719. 10,11. Helisoma cantpanulatum wisconsinense (Winslow). Tomahawk Lake, Wisconsin. B1725. 12,13. Helisoma campanulatum wisconsinense (Winslow). Tomahawk Lake, Wisconsin. B3857. 14. Helisoma campanulatum smithii (F. C. Baker). Douglas Lake, Michigan. Holo- type. B1054. 15,16. Helisoma campanulatuui smithii (F. C. Baker). Douglas Lake, Michigan. Para- types. B1728. 17-20. Helisoma campanulatum smithii (F. C. Baker). Douglas Lake, Michigan. Type locality. B3861. 21. Helisoma campanulatum rideauense F. C. Baker. Rideau River, Ottawa, Canada. Holotype. U.S.N.M., 346627. 22-24. Helisoma campanulatum rideauense F. C. Baker. Rideau River, Ottawa, Canada. Paratypes. U.S.N.M., 346627. 25. Helisoma campanulatum smithii (F. C. Baker). Douglas Lake, Michigan. Small form. B1056. 26-28. Helisoma midtirolvis (Case). Howe Lake, Marquette Co., Michigan. U.I.. Z23192. 29. Helisoma multivolvis (Case). Howe Lake, Marquette Co., Michigan. U.S.N. M., 272274. All figures are enlarged about iy> diameters niustrations of the Anatomy and of Shells 26 455 *^. 1^ J n 'S^ I (S 27 28 PLATE 109 29 456 The MoUuscan Family Planorhidae PLATE 110 Shells of Planorbidac 1-4. Helisoma cainpanulatum wiscon-'iinensc (Winslow). Tomahawk Lake, Wisconsin. 1, 2. Immature. 3, 4, Small form. U.I., Z29858. 5-7. Helisoma campanulatum near variety smithii (F. C. Baker). Douglas Lake, Michigan. U.I.. Z13957. 8-10. Helisoma campanulatum smithii (F. C. Baker). Doughis Lake, Michigan. Small form. B1056. 11. Helisoma campamilatum canadense F. C. Baker. Bamiji Lake, Ontario, Canada. Holotype. U.L, Z30721. 12, 13. Helisoma campanulatum canadense F. C. Baker. Bamiji Lake, Ontario, Canada. Paratypes. U.L, Z30721. 14. Helisoma campanulatum canadense F. C. Baker. Brent Lake, Ontario, Canada. U.L, Z41303. 15-17. Helisoma campanulatum canadense F. C. Baker. Lake near Lake Mercutio, Ontario, Canada. Variation in size. LT.L, Z40064. 18-20. Helisoma campanulatuin canadense F. C. Baker. Sturgeon Lake, Ontario, Canada. Variation in size. U.L, Z32331. 21. Helisoma campanulatum pleistocenicum F. C. Baker. White Pond, Marlboro, New Jersey. Holotype. U.S.N.M., 121195. 22-26. Helisoma campanulatum pleistocenicum F. C. Baker. AVhite Pond, Marlboro, New Jersey. Paratypes. U.S.N.M., 121195. 27-35. Helisoma campanulatum collinsi F. C. Baker. Cameron Lake, Lake of the Woods, Canada. Variation in size. U.L, Z41297. All figures are enlarged about two diameters lUuslratnn,, oj the A„at,w,u and 0/ Sh.\h 457 cm r 14 19 #^ 23 V-^/ .3^S 10 15 11 12 16 17 20 ^*^ 21 24 e 25 26 # _ '^i..l C^ 28 29 30 ^^;.^ '/ 32 33 34 PLATE 110 13 18 22 27 31 35 458 The Molluscan Family Planorhidae PLATE 111 Shells of Planorbidae 1-5. Hclisoma camptuiulatuin rudentis (Dall). Knee Lake, Manitoba, Canada. Para- types. U.S.N.M., 365574. 6,7. Helisoma carnpanidalum michiganense F. C. Baker. Marl Lake, Roscommon Co., Michigan. 6, holotype, B1809; 7, paratype, B1809a. 8,9. Helisoma cainpaitidatum michiganense F. C. Baker. Marl Lake, Roscommon Co., Michigan. U.S.N.M., 173102. 10, 11. i/(7i.som« campauulatum ))iichiganeyise F. C. Baker. Marl Lake, Michigan. U.S.N.M., 173102. 12,13. Helisoma campanulatinn dalli F. C. Baker. Anticosti Island, Canada. 12, holo- type; 13, paratype. U.S.N.M., 162724. 14. Hclisoma campanulatum michiganense F. C. Baker. Marl Lake, Michigan. Ab- normal. U.S.N.M., 173102. 15,16. Helisoma campanulatum dalli F. C. Baker. Anticosti Island, Canada. Para- types. U.S.N.M., 162724. 17-19. Helisoma campanulatniii colUnsi F. C. Baker. Cameron Lake, Lake of the Woods, Ontario, Canada. 17, holotype; 18, 19, paratypes. U.I., Z41297. 20. Helisoma campanulaUim collinsi F. C. Baker. Cameron Lake, Lake of the Woods, Canada. Paratype. A small specimen. U. I., Z41297. 21,22. Helisoma catnpanulatum (Say). Crooked Lake, Emmet Co., Michigan. Young. B3868. X31/2. 23-31. Helisoma scalare (Jay). Everglades, Florid;i. Marl bed 10-15 ft. under peat. Variation toward seminole form. LT.S.N.M., 348566. 32. Hclisoma duryi seminole Pilsbry. Lake Apopka, Florida. Showing advanced lower part of aperture in contrast with the receding aperture of scalare (fig. 31). U.S.N.M., 566570. All figures, excepting 21 and 22, are enlarged about 1% diameters Illustrations oj the Anatutny and of Shells 459 £b| i\ 10 /-^•..i^ €■ 11 12 4 9 13 9% 4 22 23 24 ^^^"^ 4 c#rf 27 28 29 30 PLATE 111 31 32 460 The MoUuscan Family Plauorhidae PLATE 112 Shells of Planorbidae 1-6. Helisoma duryi seminole Pilsbry. Lake Apopka, Florida. Range of variation. U.S.N.M., 506868. 7,8. Helisoma duryi seminole PiLsbry. Lake Apopka. Florida. scalare-Wke forms. U.S.N.M., 506870. 9-11. Carinifex newberryi (Lea). Owens Lake, California. U.S.N.M., 251516. 12-14. Carinifex occidentalis Hanna. Eagle Lake, Lasen Co., California. U.S.N.M., 120331. 15. Carinijex occidentalis Hanna. Eagle Lake, California. U.S.N. M., 120333. 16-21. Carinifex occidentalis Hanna. Eagle Lake, California. U.S.N.M., 120331. Figures 12-21 show range of variation All figures are enlarged about 1% times 1 11 ust rat ions of the Anatomy and of Shells 461 h 2 \ 10 .rf^*^,a ^ 12 n 14 11 ^m^ 15 16 17 18 19 20 PLATE 112 ^---s 21 462 The Molluscan Family Planorbidae PLATE 113 Shells of Planorbidae 1-4. Carinifex newbcrryi (Lea). Canoe Creek, California. Type locality. U.S.N .M., 9254. 5,6. Ccirinifex newbernji (Lea). Canoe Creek, California. Said to be types. See Binney, p. 75. U.S.N.M., 9256. 7,8. Carinifex newberryi (Lea). Canoe Creek, California. Lea Collection, probablj^ types. See Binney fig. 120. U.S.N.M., 120991. 9. Carinifex newberryi (Lea). Canoe Creek. California. Similar in form to malleata. U.S.N.M., 2954. 10,11. Carinifex newberryi (Lea). Canoe Creek, California. LT.S.N.M., 56405. 12-15. Carinifex newberryi (Lea). Walker Lake, Nevada. U.S.N.M., 349132. 16-23. Carinifex newberryi (Lea). Lakota Resort, Bear Lake, Utah. B3877. 24-28. Carinifex newberryi malleata Pilsbry. Pitt River, California. U.S.N.M., 9341. 29. Carinifex newberryi malleata Pilsbry. Pitt River, California. U.S.N.M., 170772. 30. Carinifex newberryi malleata Pilsbry. Pitt River, California. Binney's fig. 122. U.S.N.M., 9342. All figures are enlarged about 1% diameters niust rations of the Anatomy and of Shells 463 t^ e 10 n 14 15 1^ '^' 19 16 20 12 13 n \% 0' 21 22 r / 23 24 25 ^fl ■ ^^^ 27 28 29 PLATE 113 30 464 The MoUuscan Family Plauorhidae PLATE 114 Shells of Planorbidae 1. Carinijex ponsonbiji E. A. Smith. Lower Klamath Lake. Klamath Falls, Oregon. U.S.N.M., 334389. 2. Carinijex 'ponsonhyi E. A. Smith. Lower Klamath Lake, Klamath Falls, Oregon. U.S.N.M., 219749. 3, 4. Carinijex ponsonhyi E. A. Smith. South end Upi)er Klamath Lake, Oregon. B3924. 5,6. Carinijex ponsonhyi E. A. Smith. South end Upper Khimath Lake, Oregon. 5, immature. B3924. 7-9. Carinijex ponsonhiji E. A. Smith. Lower Klamath Lake, Oregon. U.S.N.M., 337022. 10,11. Carinijex ponsonhyi E. A. Smith. Upper Klamath Lake, Oregon. U.S.N. M., 380807. 12, 13. Carinijex ponsonhyi E. A. Smith. Lower Klamath Lake, Oregon. U.S.N. M., 334387. 14,15. Carinijex neieherryi (Lea). Canoe Creek, California. Inunature. IT .S.N. M., 9256. 16. Carinijex newberryi (Lea). Canoe Creek, California. Immature. U.S.N.M., 56405. 17. Carinijex occidentaUs Hanna. Eagle Lake, California. Immature. U.S.N.M., 120333. 18. Carinijex ponsonhyi E. A. Smith. Klamath Falls, Lower Klamatli Lake, Oregon. Immature. U.S.N.M., 510024. 19-24. Carinijex newberryi minor Cooper. Clear Lake, California. From Lea coll. U.S.N.M., 121025. 25-28. Carinijex newherryi subrotuncla Pilsbry. Proc. Acad. Nat. Sci. Phil., 86, plate 11, figs. 2, 2a, 2b, type; 3, paratype. Figures 1-13, 25-28 are enlarged about li/-> diameters; figs. 17-24 are enlarged 3 diameters. IUustratio)is oj the Anatoiny and of Shells 465 W ^w ^^^ 14 15 %^^ 16 17 18 1i^% 21 ^ 25 466 The Molluscan Family Planorhidae PLATE 115 Shells of Planorbidae 1. Helisoma caribacum (Orb.). Jocolo, Guatemala. Immature. B3869. 2-4. Helisoma caloderma (Pilsbry). Esmeralda, Guatemala. Cotypes. U.I., Z28577. 5-7. Helisoma eyerdami Clench and Aguayo. Lake Miragoane, 2 miles southeast of Miragoane, Haiti. Paratypes. M.C.Z., 83888. 8, 9. Carinijex jacksonensis J. Henderson. Jackson's Lake, Wj-oming. From type lot. B3925. 10-13. Carinijex jacksonensis J. Henderson. Jackson's Lake, Wyoming. From type lot. U.S.N.M., 510045. 14. Porapholyx klamathensis F. C. Baker. East side Upper Klamath Lake, 13 miles north of Klamath Falls, Oregon. Holotype. U.S.N.M., 406024. 15-17. Parapholyx klamathensis F. C. Baker. Same locality as above. Paratypes. U.S.N.M., 406024. 18. Parapholyx klamathensis F. C. Baker. Same locality as above. From type lot. U.S.N.M., 406024. 19. Parapholyx klamathensis F. C. Baker. Same locality as above. From type lot; slightly co.state. U.S.N.M., 406024. 20. Parapholyx klamathensis F. C. Baker. Same locality as above. From type lot; with diagonal grooves. U.S.N.M., 406024. 21-23. Parapholyx klamathensis F. C. Baker. Klamath Falls, Oregon. Small form. No. 23, costate. U.S.N.M., 219748. 24-26. Parapholyx effusa costata (Hemphill). Dalles of the Columbia River, Oregon. Type locality. U.S.N.M., 47520. 27. Parapholyx effusa dalli F. C. Baker. Klamath Falls, Oregon. Holotype. U.S.N.M., 219747. 28-30. Parapholyx effusa dalli F. C. Baker. Klamath Falls, Oregon. Paratypes. U.S.N.M., 219747. Figures 1-7, 24-30 are enlarged about four diameters; figs. 8-23 are enlarged about two diameters. lllusiratioDs of the Anatomy niid of Shells 467 ^9 ^ i^ \ ij^ ' 10 14 15 18 19 i4i^ 24 25 W 27 12 13 16 17 21 20 22 26 m 28 29 PLATE 115 23 ^; diameters Illustrations oj the Anatomy and of Shells 471 ^^ ^«^ -• 0W 9 10 11 ««iP^P^>^F ^9 v^ ^ ^(r 21 22 23 24 ^ff^ 25 26 27 \ ^- -^ 28 29 platp: 117 30 472 The MoUuscan Family Planorbidae PLATE 118 Shells of Planorbidae 1. Planorbula armigcra (Say). East Nebraska. U.S.N.M., 526054. 2. Planorbula armigera palustris F. C. Baker. Mason City, Iowa. U.S.N.M., 527656. 3. Planorbula crassilabris (Walker). Douglas Lake, Michigan. U.S.N.M., 251213. 4. Planorbula armigera indianensis F. C. Baker. Mt. Vernon, Indiana. U.I., Z2891. 5. Planorbula jenksii (H. F. Carpenter). Nayat, Rhode Ishind. B1195. 6. Planorbula smithi F. C. Baker. Stevenson, Alabama. U.S.N.M., 321196. 7. Planorbula ivhcatleyi (Lea). Bohgee, Alabama. B1194. 8. Planorbula campestris (Dawson). High Bluff, Manitoba. U.S.N.M., 63393. Figures 1-8 show the folds within the aperture of each species 9. Planorbula armigera (Say). East Nebraska. U.S.N.M., 526054. 10. Planorbula jenksii (H. F. Carpenter). Medford, Massachusetts. U.S.N.M., 41411. 11. Planorbula smithi F. C. Baker. Stevenson, Alabama. U.S.N.M., 321196. 12. Planorbula smithi F. C. Baker. Stevenson, Ahibama. Specimen with double parietal lamella. U.S.N .M., 321196. Figures 9-12 show the form of the parietal lamella in three species 13-15. Planorbula armigera (Say). East Nebraska. U.S.N .M., 526054. 16. Planorbula armigera variety? Camp Colfax, La Porte Co., Indiana. U.I., Z27094a. 17-19. Planorbula armigera variety? Camp Colfax, Indiana. U.I., Z27094b. 20-22. Planorbula crassilabris (Walker). Hamtramck, Wayne Co., Michigan. Type locality. B1200. 23-25. Planorbula crassilabris (Walker). Carr's Slough, Brookston, White Co., Indiana. U.I., Z27086. 26. Planorbula armigera variety? Big slough near Mason City, Iowa. Pathologic. U.S.N.M., 527656. 27-30. Planorbula jenksii (H. F. Carpenter). Nayat, Rhode Island. B1195. 31. Planorbula armigera (Say). East Nebraska. U.S.N.M., 526054. 32. Planorbula crassilabris (Walker). Brookston, Indiana. U.I., Z27086. 33. Planorbula wheatleyi (Lea). Boligee, Alabama. B1194. Figures 31-33 show condition of crest behind aperture All figures are enlarged about four diameters Illustrations of the Anatomy and of Shells 473 10 11 13 16 14 17 ^^ 18 15 ^im 26 19 31 32 20 21 22 27 28 33 12 23 24 25 29 30 PLATE 118 474 The Molluscan Family Planorhidae PLATE 119 Shells of Planorbidae 1-3. Planorbula armigera iiidianeyisis F. C. Baker. Uniontown Road, 2 miles southwest of Mt. Vernon, Indiana. 1, holotype; 2, 3, paratypes. U.I., P2833. 4-6. Planorbula jenksii (H. F. Carpenter). Medford, Massachusetts. U.S.N.M., 41411. 7,8. Pkmorbula wheatlcyi (Lea). Catoma, Montgomery Co., Alabama. Type. U.S.N. M., 29292. 9. Planorbula irhcatlcyi (Lea). Catoma Creek, Montgomery Co., Alabama. U.S.X.M., 120929. 10. Planorbula smithi F. C. Baker. Stevenson, Alabama. Holotype. U.S.N.M., 321196. 11, 12. Planorbula smithi F. C. Baker. Stevenson, Alabama. Paratypes. U.S.N.M., 321196. 13. Planorbula christyl (Dall) {^ campestris Dawson). High Bluff, Manitoba. Figured type, Alaska Moll., plate ii, figs. 10, 11. U.S.N.M., 63393. 14,15. Planorbula christyl (Dall). High BlutT. Manitoba. Paratypes. U.S.N.M., 63393. 1(5-21. Helisoma columbiense F. C. Baker. Lake La Hache, Caribou Dist., British Columbia. 16, holotype; 17-21, paratypes. M.C.Z., 93710. 22-25. Helisoma caribaeum cubcnse F. C. Baker. Zapata Swamp, Cuba. Marl between layers of peat. 22, holotype; 23-25, paratypes. U.S.N.M., 404719. Figures 1-15 are enlarged about 3^/4 diameters; figs. 16-25 are enlarged about 1% diameters. Illustrations of the Anatoiity and of Shells 475 476 The Molluscan Family Plauorbidac PLATE 120 Shells of Planorbidae 1-10. Menetus opercularis (Gould). Mountain Lake, San Francisco, California. U.S.N.M., 47627. 11,12. Menetus cooperi F. C. Baker { = planulatus Cooper). Whidby's Island, Puget Sound, Washington. Type locality. U.S.N.M., 152185. 13. Menetus cooperi F. C. Baker. Whidby's Island, Puget Sound, Washington. Holo- type of M. planulatus. Binney's fig. 209 (No. 9118). U.S.N.M., 29280a. 14. Menetus cooperi F. C. Baker. Whidby's Island, Puget Sound, Washington. Co- type of M. planulatus. U.S.N.M., 29280. 15-18. Menetus cooperi F. C. Baker. Lake Union, Washington. U.S.N.M., 253617. 19-21. Menetus cooperi callioglyptus (Vanatta). Freeport, Washington. Cotypes. Hemphill coll. U.S.N.M., 47630. 22. Menetus cooperi F. C. Baker. Olga, Washington. U.S.N.M., 216936. 23-26. Menetus cooperi rnultilineatus (Vanatta). Pass Lake, Fidalgo Island, Washing- ton. U.S.N.M., 346742. 27. Menetus cooperi F. C. Baker. Bellingham, Washington. Very flat spire. IT .S.N. M., 525100. 28. Menetus cooperi F. C. Baker. Lake Washington, Seattle, Washington. U.S.N, M., 169070. 29-31. Menetus cooperi midtilineatus (Vanatta). Salem, Oregon. Type locality. B3927. 32. Parapholyx solida optima (Pilsbry). Lake Bigler, Nevada. Paratype. A.N.S.P., 125363. Figures 1-31 are enlarged about four diameters; fig. 32 is enlarged two diameters. Illustrations of the Anatonnj and of Shells 477 \ o hi\\ 10 11 12 13 14 15 16 ^ 17 18 19 20 21 ^^^i 22 23 24 /^ 25 26 27 28 9"' ^ ^^ 29 30 31 32 PLATE 120 478 The Molluscan Family Planorhidae PLATE 121 Shells of Planorbidae 1-5. Menetus ccntcrvillcnsk (Tryon). Novo, California. U.S.N .M., 47639. 6-8. Menetus ceniervillemis (Tryon). Bear Lake, San Bernardino Mt.s.. California. U.S.N.M., 175089. 9, 10. Menetus labiatus F. C. Baker. Terminal Island, Los Angeles Co., California. Paratypes. U.S.N. M., 190021. 11. Menetus labiatus F. C. Baker. Terminal Island, Los Angeles Co., California. Holotype. U.S.N.M., 190021. 12-18. Menetus portlanclensis F. C. Baker. Tanner Creek, Portland, Oregon. 12, holo- type; 13-18, paratypes. U.S.N.M., 184182. 19,20. Meyietus cooperi crassilabris F. C. Baker. Seattle, Washington. 20, holotype; 19, paratype. U.S.N.M., 214590. 21. Menetus cooperi crassilabris F. C. Baker. Portland, Oregon. U.S.N. M., 99302. 22,25. Menetus dilatatus (Gould). Hingham, Massachusetts. Lea coll. Type locality. U.S.N.M., 121002. 23,27,28. Menetus dilatatus buehanensis (Lea). Cincinnati, Ohio. Lea coll. Types. U.S.N.M., 120948. 24,30. Menetus dilatatus buehanensis (Lea). Half mile west of Luray, Virginia. Varia- tion toward dUatatus. U.S.N.M., 473961. 26. Menetus dilatatus (Gould). Medford, Massachusetts. U.S.N.M., 41725. 29. Menetus dilatatus buchanenMs (Lea). Near Luray, Virginia. Pathologic. U.S.N.M., 473961. 31. Menetus dilatatus buehanensis (Lea). Mt. Pleasant, District of Columbia. U.S.N.M., 227832. 32,35,36. Menetus dilatatus pennsylvanicus PiLsbry. Three and one-half miles south- west of Cambridge, Maryland. B168. 33. Menetus dilatatus buehanensis (Lea). Harbert, Berrien Co., Michigan. U.M., 88030. 34. Menetus alahaniensis (PiLsbry). Woodville, Jackson Co., Alabama. Type locality. U.M., 85913. 37. Menetus alabamensis (Pilsbry). Woodville, Alabama. Part of tyjie lot. B3928. 38. Menetus alabamensis (Pilsbry). Woodville, Alabama. Type locality. U.M., 85913. 39. Menetus alabamensis (Pilsbry). Woodville, Alabama. Paratype. U.S.N.M., 129005. 40,41. Menetus alabamensis avus (Pilsbry). Hammock near St. Johns River, Florida. U.S.N.M., 101698. 42-44. Menetus brogniartianus (Lea). Cincinnati, Ohio. Lea coll. 42, lectotype; 43-44, paratypes. U.S.N.M., 120981. Illustrations of the Auatoiiiy ruid of Shells 479 ^^^^^# 10 15 16 17 20 21 18 22 23 19 24 25 30 31 26 27 28 29 32 33 34 ^' ' ^i ■■■ ^^ 35 36 37 38 39 42 40 41 43 44 PLATE 121 480 The Molluscan Family Planorhidae PLATE 122 Shells of Planorhidae 1,2. Menetus cooperi F. C. Baker. Blue Lake, Grand Coulee, Washington. B3935. 3-6. Menetus cooperi planospirus F. C. Baker. Orcas Island, Puget Sound, Wash- ington. Figure 5, holotype; 3, 4, 6, paratypes. Figure 5 shows well the very flat spire. M.C.Z., 31583. 7. Menetus cooperi F. C. Baker. Two miles north of Petaluma, California. U.S.N.M., 531171. 8. Menetus cooperi calUoghjptus (Vanatta). Quamichan Lake, British Columbia. B2030. 9-12. Menetus cooperi multilincatus (Vanatta). Salem, Oregon. Type locality. B3929. 13. Menetus cooperi crassilabris F. C. Baker. Colma, San Mateo Co., California. U.S.N.M., 525095. 14. Promenetus exncuous (Say). Chimney Point, Hospital Creek, Lake Champlain, Vermont. U.S.N.M., 336591. 15-18. Promenetus exacuous (Say). New York, New York. B3930. 19. Promenetus exacuous (Say). West Lake Okoboji, Iowa. U.S.N.M., 475975. 20-22. Promenetus exacuous mcgas (Dall). Birtle, Manitoba. Types. U.S.N.M., 63391. 23-25. Menetus coloradoensis F. C. Baker. Swamp, head of Eldora Lake, near Eldora, Colorado. Figure 25, holotype; 23, 24, paratypes. U.C, 10114. 26-28. Promenetus exacuous variety? Gresham Lake, between Gresham and Ward, Boulder Co., Colorado. U.C, 526. All figures are enlarged about four diameters Illustrations oj the Anatomy and of Shells 481 PLATE 122 482 The Molluscan Family Planorbidae PLATE 123 Shells of Planorbidae I. Menetus alabamensis avus (Pilsbry). South end Lake Panasofflee, Sumter Co., Florida. U.S.N.M., 211002. 2-10. Parapholyx klamathensis sinitsini F. C. Baker. Bercley Spring, 14 miles north of Klamath Falls, Oregon. Figure 2, holotype; 3, 4, paratypes; U.S.N.M.. 531029. Figures 5-10, locotypes; U.S.N. M., 531064. II. Menetus sampsuni (Ancey). Pond in Flat Creek bottom, near Sedalia, Missouri. Part of type lot. B166. 12,13. Menetus alabatnensis (Pilsbry). Temporary pond half mile south of Fountain, Illinois. B3923. 14-16. Menetus sampsoni (Ancey). Pond in Flat Creek bottom, near Sedalia, Missouri. Type locality. M.C.Z., 4900. 17-19. Promenetus hudsonicus (Pilsbry). Four miles southeast of Canandaigua, in beach pond, east side Canandaigua Lake, New York. B2904. 20-22. Menetus dilatatus floridensis F. C. Baker. St. Johns River, Palatka, Florida. Figure 20, holotype; 21, 22, paratypes. U.S.N.M., 37585. 23-25. Menetus uUgmosu-s (Vanatta). Devonshire Swam]), near Hamilton, Bermuda. M.C.Z., 108996. 26. Menetus cooperi crassilabris F. C. Baker. Colma, San Mateo Co., California. U.S.N.M., 525095. 27,28. Menetus uUginosus (Vanatta). Proc. Phil. Acad. Sci., Vol. 62, p. 669, f^g. 2. Pembroke Marsh, near Hamilton, Bermuda. Types. 29,30. Promenetus imus (Vanatta). Proc. Phil. Acad. Sci., Vol. 62, p. 669, fig. 3. Bermuda. Types. 31-33. Menetus sampsoni (Ancey). Meredosia, Illinois. B2018. Zi,35. Pro7nenetus umbilicateUus (Ckll.). Plummers Point, Lake Butte des Morts, Wisconsin. B2101. 36. Promenetus umbilicateUus (Ckll.). L"'^pper Dells, Kilbourn, Wisconsin. B2102. 37-39. Promenetus rubellus (Sterki). Ditch south of New Philadelphia, Ohio. Cotypes. B160. Figures 2 to 10 are enlarged about two diameters; figs. 1, 11 to 26, 31 to 33, 37 to 39, six diameters; figs. 34 to 36, four diameters; figs. 27 to 30, one-half size of original figures, but enlargement of shells is about five diameters. Illustrations of the Anatonnj and of Shells 483 •i*^« %r< 2 3 .•«a>... ^ * 5 ^6 # # 9 10 11 13 14 17 20 23 27 ^EL ^is0 ^BR 18 21 24 15 ^B^ 19 22 25 28 29 16 32 35 30 26 41^ 33 » ) 36 38 31 34 37 PLATE 123 39 484 The Molluscan Family Plauorbidae PLATE 124 Shells of Planorbidae 1,2. Drepanotrema anatimim (Orb.). Para, Brazil. U.S.N.M., 348535. 3. Drepanotrema anatinum (Orb.). Para, Brazil. M.C.Z., 72832. 4-6. Drepanotrema anaiinmn (Orb.). Lake Miragoane, two miles SE of Miragoane, Haiti. M.C.Z., 83729. 7. Drepanotrema anatinum (Orb.). Jamaica. {^ Planorhis haldemani C. B. Adams.) Lea Collection, probably part of original lot of haldemani. U.S.N .M., 94758. 8-10. Drepanotrema anatinum (Orb.). Esperanza, Cuba. Type locality of Planorbis esperanzensis Tryon. M.C.Z., 85875. 11-13. Drepanotrema anatinum (Orb.). Baron Hills, Trelawny, Jamaica. {^^ Planorbis haldemani C. B. Adams.) M.C.Z., 65839. 14-20. Drepanotrema parapseide (Orb.). Buena Vista, Santa Cruz, Bolivia. U.M., 87196. 21-28. Drepanotrema ahenum H. B. Baker. Tuccas, Venezuela. Type lot, showing age variation in shell. U.M., 87164. 29,31,32. Drepanotrema lucidum (Pfr.). Juninaguas, Dept. Loreto, Peru. U.S.N.M., 381510. 30. Drepanotrema anatinum (Orb.). Juninaguas, Dept. Loreto, Peru. LT.S.N.M., with 381510. All figures are enlarged about foiu- diameters Illustrations of the Aiiatonnj and of Shells 485 12 10 n 9^9 ^4 15 13 16 »»a. PLATE 124 486 The Molluscan Family Plauorbidae PLATE 125 Shells of Planorbidae 1,4,6,7. Drepanotrcma lucidum (Pfeiffer). Lagumi del Bili, Alacranes Mts., Cuba. M.C.Z., 129991. 2,3. Drepanotrema lucidum (Pfeiffer). St. Louis, Dejit. du Sud, Haiti. Immature shells. U.S.N.M., 402809. 5. Drepanotrema Incidum (Pfeiffer). Maggoty, St. Elizabeth, Jamaica. IT .S.N. M., 376088. 8. Drepanotrema lucidum (Pfeiffer). Jamaica. {^^ Pkntorbis redfieldi C. B. Adams.) Lea Collection. Possibly part of original lot of redfieldi. U.S.N.M., 94757. 9, 10. Drepanotrema lucidum (Pfeiffer). Jealousy Stream, St. Croix. U.S.X.M., 423966. 11-17. Drepanotrema lucidum (Pfeiffer). Large variety with closely coiled whorls. Half mile NE of Orange Creek, Cat Island, Bahamas. M.C.Z., 107179. 18-21. Drepanotrema melleum (Lutz). Rio de Janeiro, Brazil. U.S.N.M., 535918. All figures are enlarged about four diameters Illustrations of the Anatomy and of Shells ^1 487 488 The MoUuscan Family Planorhidae PLATE 126 Sliells of Planorbidae 1-5. Drepanotrcma castcuuonitcns (Pils. and Van.). Near Maldonado, Uiuguaj'. Tj-pe locality. U.S.N.M., 151668. 6. Drepanotrcma hofftnanni F. C. Baker. Isabela, Puerto Rico. Holotype. B3952. 7-9. Drepanotrema hoffmanni F. C. Baker. Isabela, Puerto Rico. Paratypes. B3953. 10-12. Drepanotrema hojfmanni F. C. Baker. Near San Juan, Puerto Rico. Age variation. U.S.N.M., 420573. 13. Drepanotrema kermatoide (Orb.). Puerto Haberton, Argentina. U.S.N. M., 362857. 14-16. Drepanotrema kermatoide (Orb.). Lima, Peru. Type locality. Figure 14 shows an immature specimen. LT.S.N.M., 20705. 17-19. Drepanotrema ciiltratum anitense (Cooper). Laguna, Santa Rita, Lower Cali- fornia. U.S.N.M., 129292. All figures are enlarged about four diameters lUustratiois oj the Anatomy and of Shells 489 / ^^^^h^p^" i V \ 10 ^tSg^'^^ .'''V^iSV^'^ajj^^ 13 11 14 15 17 /' 12 16 m J 19 18 PLATE 126 490 The Molluscan Famih/ Planorbidae PLATE 127 Shells of Planorbidae 1-3. Drepanotrema cimcx (Moricand). Valle de Yumuri, Matanzas, Cuba. M.C.Z., 129995. 4-6. Drepanotrema cultratum (Orb.). Painters Pond, Painters, Antigua. U.S.N. M., 272282. 7,8. Drepanotrema cimex (Moricand). Hunts Bay, St. Andrew, Jamaica. U.S.X.M., 378054. 9-12. Drepanotrema cultratum duenafsianum (Tristram). Pools alono; i-aihvay near Lake Amatitlan, Guatemala. B1258. 13-15. Drepanotrema cimex pistiae H. B. Baker. Rincon del Valle, near Caracas, Venezuela. U.S.N.M., 362133. IQ. Drepanotrema cimex (Moricand). Jamaica. {^ Planorbis macnabianus C. B. Adams.) Lea Collection, probably part of original lot. U.S.N.M., 94756. 17-19. Drepanotrema depressissimum (Moricand). Bahia, Brazil. Paratypes. M.C.Z., 31432. All figures are enlarged about four diameters Illustrations of the Anatotny and of Shells 491 492 The Molluscan Family Planorhidae PLATE 128 Shells of Planorbidac 1.2. Drcpanotrema cultratum panuco Pilsbry. Tampico, Mexico. B1183. 3-5. Drepanotrema cultratum panuco Pilsbry. Pasture west of San Dieguito, San Luis Potosi Co., Mexico. Locotypes. B2124. 6. Drcpanotrema cultratum labrosum Pilsbry. Brownsville, Texas. U.S.N. M., 273933. 7-10. Drepanotrema cultratum labrosum Pilsbry. Brownsville, Texas. Locotypes. B1192. 11-16. Drepanotrema sumichrasti (Crosse and Fischer). Barbovu' Lathrop Trail, Barro Colorado Island, Gatun Lake, Canal Zone. B3967. 17-19. Drepanotrema cimex (Moricand). Brazil. U.S.N.M., 121018. 20-22. Drepanotrona cimex (Moricand). Anapolis, Guyoz, Brazil. M.C.Z., 65716. 23-25. Drepanotrema peninsularis (Cooper). {^Drepanotrema anathuon) . Santa Anita, Lower California. U.S.N.M., 129291. 26-30. Tropicorbis obstructns (Morelet). Tampico, Mexico. U.L, Z28550. 31-33. Tropicorbis obstructns (Morelet). Lake Amatitlan, Guatemala. B2125. Figures 1 to 30 are enlarged about five diameters; figs. 31 to 33 are enlarged about four diameters. Illustrations of the Anatomy and of Shells 493 11 26 12 m 27 13 ^1 28 14 i^**^. ^ 29 15 # 30 16 © 10 31 17 20 23 c il 18 24 V it. # ^^ 19 22 25 33 22 25 PLATE 128 494 The Molluscan Family Planorbidae PLATE 129 Shells of Planorbidae 1-3. Tropicorbis orbiculus (Morelet). Near San Miguel, Cozumel Island, Quintana Roo, Mexico. M.C.Z., 75102. 4. Tropicorbis obstructus (Morelet). Same as above. M.C.Z., 75102. 5-7. Tropicorbis orbiculus (Morelet). {^^ Planorbis licbmanni Dunker). Vera Cruz, Mexico. U.S.N.M., 210881. 8,9. Tropicorbis obstructus (Morelet). Same locality as above. U.S.N .M., 210881. 10-15. Tropicorbis orbiculus (Morelet). Chamiai Creek, below Valles, Mexico. U.I., Z28528. 16. Tropicorbis orbiculus (Morelet). Catanas Lake, El Abra, Mexico. B1191. 17-22. Tropicorbis obstructus donbilli (Tristram). Edentate. Guadalupe River, Victoria Co., Texas. U.S.N.M., 464970. 23-25. Tropicorbis obstructus donbilli (Tristram). Edentate. Brownsville, Texas. B1187. 26-31. Tropicorbis orbiculus dunkcri F. C. Baker. New name. Dry pool near Tampico, Mexico. B1184. 32-36. Tropicorbis orbicidus dunkcri F. C. Baker. Los Canoas, Mexico. B2113. 37-42. Drepanotrema heteropleurus Pilsbry and Vanatta. Lake Titicaca, Peru. Topo- types. Agassiz Expedition. All figures are enlarged about two diameters llhstrations of the Anatomy and of Shells 495 _« /§■* v^^ 10 n 17 .* 3 7 ( 18 12 V 19 f) 13 37 38 ^^ 26 27 28 20 14 ^(^^. 15 39 21 # 22 16 40 ')> "> 29 32 41 30 ^^ 3^ 33 36 23 34 24 v5^ 35 25 PLATE 129 496 Tiie Molluscan Family Planorbidae PLATE 130 Shells of Planorbidae 1-3. Tropicorbis gracilcntus (Gould). Colorado Desert. Binney's fig. 183, p. 108. Holo- type. U.S.N.M., 26477. 4-12. Tropicorbis gracilentus (Gould). San Marcos, Texas, in drift adjoining fish hatchery. Figure 10 shows closely coiled whorls like those of Tropicorbis orbi- culus. B3298. 13-17. Tropicorbis maya (Morelet). Merida, Yucatan. M.C.Z., 59646. 18-20. Tropicorbis hovancnsis (PfeifTer). Havana, Cuba. Type locality. U.M., 84039. 21-25. Tropicorbis havaiicnsis (Pfciffer). New Orleans, Louisiana. A small \-ariety. B3954. 26. Tropicorbis havancnsis (Pfeiffer). Guayos, Santa Clara Prov., Cuba. U.M., 84038. 27-28. Tropicorbis havanensis (Pfeiffer). New Braunfels, Texas. M.C.Z., 13622. 29-32. Tropicorbis philippiamis (Dunker). Asuncion, Paraguay. Figure 31, loosely coiled. M.C.Z., 62490. 33,34. Tropicorbis philippianm (Dunker). Espcranza dc Santa Fe, Argentina. M.C.Z., 64963. 35-37. Tropicorbis centimeimlis (Lutz). Ceara Miriin, Rio Grande do Norte, Brazil. Type locality. M.C.Z., 92825. 38-41. Tropicorbis })crc(jrinus (Orbigny). Rio Grande de Sul, Brazil. M.C.Z., 75376. All figures are enlarged about two diameters Illustratious of the Anatomy and of Shells 497 4,. 6 9 14 j/- — 19 18 2i (^ 24 25 29 30 IZ 34 38 10 15 16 20 21 5 26 11 17 22 27 28 32 31 36 35 'v 7 G* 37 40 41 PLATE 130 498 The Molluscan Family Planorbidae PLATE 131 Shells of Planorbidae 1^. Tropicorbis isthmicus (Pilsbiy). Panama City, Panama. Type locality. U.M., 88180. 5-7. Tropicorbis isthmicus (Pilsbry). Miraflores Lake, Panama. U.M.. 88181. 8-10. Tropicorbis decipiens (C. B. Adams). Rockport, Jamaica. B3966. 11. Tropicorbis decipiens (C. B. Adams). Puerto Rico. LT.L, Z40460. 12-14. Tropicorbis chilensis (Clessin). Valparaiso, Chile. M.C.Z., 74655. 15-24. Tropicorbis obstructus donbilli (Tri.stram). Dr\' pool in Tampico, Mexico. B1189. 25,26. Tropicorbis obstructus donbilli (Tristram). Brownsville, Texas. B127. 27-31. Taphius andecolus montanus (Orbigny). Tanja (Oroya), Peru. M.C.Z., 36702. 32-35. Taphius andecolus (Orbigny). Puoa, Peru. U.I., Z40575. 36-40. Taphius subpronus (von Martens). Terrialba, Costa Rica. U.S.N.M., 162827. Figures 1 to 35 are enlarged about two diameters; figs. 36 to 40, four diameters. lUustratiois of the Anatomy and of Shells 499 %P "^ '^>- 11 15 12 K) 19 20 13 17 21 • # il ^^ 24 25 26 28 29 30 31 ic 34 33 fgp' 37 39 36 38 PLATE 131 9t 10 /^ 14 18 #1 22 27 ) 32 35 40 500 The Molluscan Family Planorbidae PLATE 132 Shells of Planorbidae 1-3. Tropicorbis paUidus (C. B. Adams). King.ston, Jamaica. U.I., Z40466. 4,5. Tropicorbis pallidus (C. B. Adams). Tucaras, Venezuela. U.M., 89990. 6-9. Tropicorbis kuhnianus (Dunker). Bejuma, Venezuela. U.M., 89991. 10-12. Tropicorbis stramineus (Dunker). Venezuela. Paratypes. Ex Dunker. M.C.Z., 74654. 13,14. Tropicorbis stramineus (Dunker). Lagoa Giboia, Municipio de Aquraz, Ceara, Brazil. M.C.Z., 65720. 15-21. Tropicorbis riisei {'Dunker) . Lares, Puerto Rico. B3955. 22,23. Tropicorbis ineridaensis (Preston). Merida, Venezuela. VI., Z40463. 24-28. Tropicorbis fieldi (Tryon). Gatun, Panama Canal. Type locality. M.C.Z., 21187. 29,30. Tropicorbis fieldi (Tryon). Near Granada, Nicaragua. M.C.Z., 4534. 31,32. Tropicorbis bourcardianus (Preston). Mexico. U.S.N.M., 202523. 33-35. Tropicorbis gundlachi (Dunker) {^stramineus). Trinidad. U.I., Z40461. All figures are enlarged about three diameters Illustrations of the Anatomy and of Shells 501 502 The Molluscan Family Planorhidae PLATE 133 Shells of Planorhidae 1-3. Tropicorbis petenensis Morelet. Tehaimtepec, Mexico. M.C.Z., 64995. 4-9. Tropicorbis tcpiceiisis (Martens). Tepic, Guadalajara, Mexico. U.S.N.M., 102211. 10-13. Tropicorbis heloicus (Orbigny). In small creek back of the Cerro, Montevideo, Uruguay. Type locality. U.S.N.M., 535720. 14-17. Tropicorbis nigrilabris (Lutz). Rio de Janeiro, Brazil. Type locality. U.S.N.M., 535713. 18-21. Tropicorbis janeirensis (Clessin). Bahia, Brazil. U.S.N.M., 152677. 22. Tropicorbis schrammi (Crosse). Martinique. M.C.Z., 113883. 23,24. Tropicorbis schrammi (Crosse). Antigua. U.I., Z40465. 25-27. Tropicorbis dcclivis (Tate). Nicaragua. U.S.N.M., 24006. 28-33. Tropicorbis obstructiis (Morelet). Pool at Piste, Yucatan. M.C.Z., 59754. 34,35. Tropicorbis obstructus (Morelet). Falls of the Valles River, Valles, Mexico. B2117. 36-40. Tropicorbis obstructus anodontus (Pilsbry). Reservoir north of Guatemala City, Guatemala. Type locality. B2061. All figures are enlarged about three diameters Illustrations of the Anatomy and of Shells 4 >. 5 503 12 13 14 % 6. 16 ^ 17 J^ 34 m 18 19 20 21 22 23 25 26 35 27 PLATE 133 28 29 30 31 32 33 36 • 37 38 fti ^ 39 • 40 504 The Molluscan Family Planorbidae PLATE 134 Shells of Planorbidae 1-3. Tropicorbis paparyc7isis (F. Baker). Anapolis, Goyaz, Brazil. M.C.Z., 65717. 4-6. Tropicorbis albicans (Pfr.). Cuba. U.I., Z40459. 7. Tropicorbis schrammi (Crosse). Antigua. U.I., Z40465. 8,9. Tropicorbis dentiferus (C. B. Adams). Bog Walk, St. Catherine, Jamaica. M.C.Z., 65838. 10,11. Tropicorbis obstruents (Morelet). Catamas Lake, El Abra, Mexico. B1218. 12. Tropicorbis shimeki F. C. Baker. Ometope, Nicaragua. Holotype. U.S.N.M., 534290. 13, 14. Tropicorbis shitneki F. C. Baker. Ometope, Nicaragua. Paratypes. U.S.N.M., 534290. 15-18. Tropicorbis albicans (Pfr.). Mangrove Cay, along Kings Road, Lisbon Point, Andros Island, Bahamas. U.S.N. M., 270084. 19. Tropicorbis albicans (Pfr.). Cuba. U.I., Z40459. 20. Tropicorbis paparyensis (F. Baker). Anapolis, Brazil. M.C.Z., 65717. 21. Tropicorbis obstructus donbilli (Tristram). Tamosopo, Mexico. I^.L, Z28545. Figures 18 to 21 illustrate form of lamellae in aperture 22. Tropicorbis obstructus (Morelet). Pistae, Yucatan. M.C.Z., 59754. 23. Tropicorbis obstructus donbilli (Tristram). Tamosopo, Mexico. U.L, Z28545. 24. Tropicorbis janeirensis (Clessin). Bahia, Brazil. U.S.N.M., 152677. 25. Tropicorbis nigrilabris (Lutz). Brazil. U.S.N.M., 535713. 26. Tropicorbis paparyensis (F. Baker). Anapolis, Brazil. M.C.Z., 65717. 27. Tropicorbis schrammi (Crosse) . Martinique. U.L, Z40464. 28. Tropicorbis shimeki F. C. Baker. Coatzocoalcos, Mexico. U.S.N.M., 219696. 29. Tropicorbis albicans (Pfr.). Mangrove Cay, Andros, Bahamas. U.S.N .M., 270084. Figures 22 to 29 illustrate lamellae on parietal wall Figures 1 to 11 are enlarged about four diameters; figs. 12 to 29, six diameters. Illustrations of the Anatomy and of Shells 505 V. ii'Ty^f^j 10 11 V IS 19 20 5 12 ^ 21 15 ?► 16 17 22 13 (^ i 14 24 25 26 27 28 29 PLATE 134 506 The Molluscan Family Planorhidae PLATE 135 Shells of Planorbidae 1-3. Tropicorbis peregrinus (Orbigny). Montevideo, Uruguay. U.S.N. M., 535952. 4. Tropicorbis peregrinus (Orbigny). Arroyo de Solon, Uruguay. U.S.N.M., 380999. 5-8. Tropicorbis centimetralis (Lutz). From Lutz. U.S.N. M., 535956. 9-11. Tropicorbis chilensis (Clessin). Peru. Lea Coll. from Paris Museum. U.S.N. M., 126412. 12,13. Tropicorbis philippianus (Dunker). Lake near Coma de Ipaguaza, Bolivia (15 mi. N.E. of Yacuiba). U.S.N.M., 341049. 14-16. Tropicorbis meridaensis (Preston). Ruicon de Valle, near Caracas, Venezuela. U.S.N.M., 362132. 17-19. Tropicorbis bourcardiai^us (Preston). Manzanello, Mexico. L'.S.N.M., 219755. 20,21. Tropicorbis canonicus (Cousin). Soacha, near Bogata, Colombia. M.C.Z. 22,23. Tropicorbis canonicus (Cousin). 'La Picata' near Bogata, Colombia. M.C.Z. 24-27. Tropicorbis canonicus (Cousin). Ibarra, Ecuador. M.C.Z., 64967. 28-31. Tropicorbis trigyrus (Philippi). Small lake near Titicaca, Peru. (14,000 feet elevation). U.S.N.M., 271591. 32-35. Tropicorbis gracilentus (Gould). 30 miles S.W. of Santiago, Mexico. U.S.N.M., 28384. All figures are enlarged about 2i/l> diameters Illustrations oj the Anatomy and of Shells 507 14 10 15 ^^r i f;.^ ^^^^ 24 20 ^k 11 12 13 17 16 28 29 25 21 22 IP) 30 18 26 r 31 23 27 19 32 33 PLATE 135 34 35 508 The Molluscan Family Planorbidae PLATE 136 Shells of Planorbidae 1-3. Gyraidus albus (Miiller). Scaly Beck, near Scarborough, England. No. 3 shows fine spiral sculpture. Baker coll., 2768. 4-7. Gyraulus hirsutus (Gould). Lynnfield, Massachusetts. M.C.Z., 34915. 8-10. Gyrmdus hirsidus (Gould). Lynnfield, Massachusetts. M.C.Z., 34915. 11. Gyraulus hirsutus (Gould). Lynnfield, Massachusetts. Base of shell showing rounded whorls. M.C.Z., 34915. 12. Gyraidus hirsutus (Gould). Lynnfield, Massachusetts. Hirsute shell showing larger and less numerous rows than in albus, fig. 3. 13-15. Gyraulus deflectus (Say). Miller Bay, Lake Winnebago, Wisconsin. Baker Coll., 2036. 16,17. Gyraulus deflectus (Say). Lake Maxinkuckee, Indiana. Baker Coll., 127. 18-20. Gyraulus deflectus (Say). Miller Bay, Lake Winnebago, Wisconsin. Baker Coll. 2036. 21. Gyraulus deflectus (Say). Harbor Island. Lake George, New York. L^S.X.M., 426560. Showing hirsute periostracum. 22. Gyraulus deflectus obliquus (DeKay). Okoboji Lake. Iowa. Showing hirsute epidermis. U.S.N.M., 525319. 23. Gyraulus deflectus (Say). Lake Maxinkuckee, Indiana. Immature specimen with hairy periostracum. Baker Coll., 127. 24. Gyraulus deflectus (Say). Harbor Island, Lake George, New York. Specimen with very acute periphery and hairy periostracum. U.S.N.M., 426560. 25,26. Gyrardms deflectus (Say). Lake Maxinkuckee, Indiana. Immature. Baker Coll., 127. 27-31. Gyraulus deflectus obliciuus (DeKay). Round Pond, Charlotte, near Rochester, New York. Baker Coll., 1120. 32-37. Gyraulus borealis (Westerhmd). Tanana River, Chena, Alaska. U.S.N.M., 193289. 38. Gyraulus borealis (We.sterlund). Popoff Island, Shumigins Group, Alaska. U.S.N.M., 180292. 39. Gyraulms borealis (Westerlund). Saigan, Siberia. From Zool. Mus. Russia. Named by Westerlund. U.S.N.M., 15248. All specimens are enlarged four diameters Illustrations of the Aimtomy and of Shells 509 # 12 21 10 22 23 11 34 32 m 33 35 13 14 15 16 17 J 18 :# ^ 19 20 24 25 26 27 28 29 30 31 S^ 36 38 # 37 39 PLATE 136 510 The Molluscan Family Plauorbidae PLATE 137 Shells of Planorbidae 1-13. Taphhis andecolus (Orb.). Duli. Lake Titicaca, Peru. U.S.X.M., 251596. 14,15. Taphius pronus (Martens). From Liitz. U.S.X.M., 535957. 16.17; 19-21. Taphius proiius (Martens). Penninsula de Cobrera, Lake Valencia, Venezuela. M.C.Z., 111649. 18,22-24:. Taphius pronus (Martens). (Fossil, 110 ft.). Lake Valencia, Venezuela. B3382. 25-27. Taphius montanus (Orb.). Duli, Lake Titicaca, Peru. C. Briies. L'.S.X.M., 271598. 28. Australorbis inimunis (Lutz). Immature. Rio de Janeiro, Brazil. M.C.Z., 74578. 29,30. Australorbis immunis (Lutz). Rio de Janeiro, Brazil. M.C.Z., 74578. 31-34. Australorbis immunis (Lutz). (From Lutz) Rio de Janeiro, Brazil. U.S.X.M., 535953. 35,36. Australorbis guadcloupensis (Sowb.). Guadeloupe. Salle Coll. L'.S.X.M., 151238. Illustrations of the Anatomy and of Shells 511 ^W .^>> 11 6 9 J^ 512 The Molluscan Family Plauorbidae PLATE 138 Shells of Planorbidae 1,2. Australorbis lugubris (Wagner). Caracas, Venezuela. Lea Coll. U.S.N.M., 126406. 3,4. Australorbis lugubris (Wagner). Between Caracas and Puerto Cabello, Venezuela. Salle Coll. U.S.N.M., 336132. 5-7. Australorbis lugubris (Wagner). San Domingo, Brazil. M.C.Z.. 74588. 8,9. Australorbis lugubris (Wagner). Near Caracas, Venezuela. U.S.N.M., 426247. 10. Australorbis lugubris (Wagner). Brazil. Lea Coll. U.S.N.M., 121006. 11,12. Australorbis blauneri (Germain). Isle Vieques, Puerto Rico. Webb Coll. U.L, Z40479. 13-15,19. Australorbis bahiensis (Dunker). Montevideo, ITruguay. U.S.N.M., 124592. 16,18. Australorbis bahiensis (Dunker). Campos, Brazil. M.C.Z., 74584. 17. Australorbis bahiensis (Dunker). Campos, Brazil. M.C.Z., 74585. 20. Australorbis bahiensis (Dunker). {nigricans, from Lutz). U.S.N.M., 535955. 21-23. Australorbis bahiensis (Dunker). Victoria, Brazil. M.C.Z., 74586. 24,25. Australorbis bahiensis (Dunker). San Domingo, Brazil. M.C.Z., 74588. 26,27. Australorbis bahiensis (Dunker). Bahia, Brazil. M.C.Z., 74587. Illustrations of the Anatomy and of Shells 513 514 The Molluscan Family Planorbidae PLATE 139 Shells of Planorbidae 1,2. Austral orbis paysanduensis (Marshall). (Figured type). Paysandu, Uruguay. U.S.N.M., 380693. 3,4. Australorbis paysanduensis (Marshall). (Paratype). Paysandu, Uruguay. U.S.N.M., 380694. 5. Australorbis paysanduensis (Marshall). Paysandu, Uruguay. F. Felippo Coll. U.S.N.M., 322385. 6,7. Australorbis tenagophilus (Orb.). Corrientes, Brazil. M.C.Z., 104573. 8-10. Australorbis tenagophilus (Orb.). Montevideo, Uruguay. U.S.N.M., 380522. 11, 12. ^M.s-^ra/or6i!'s tenagophilus (Orb.). Young. Arroyo Jurical, Dept. San Jose, Uruguay. U.S.N.M., 380746. 13,14. Australorbis tenagophilus (Orb.). Arroyo Jurical, Dept. San Jose, Uruguay. U.S.N.M., 346818. 15,16. Australorbis tenagophilus (Orb.). Arroyo de Solon, Dept. Duragno, Uruguay. U.S.N.M., 380997. 17,18. Australorbis tenagophilus (Orb.). Rio Couraguam, Brazil. Von Ihering Coll. U.S.N.M., 122309. 19-25. Australorbis glabratus christopherensis Pilsbry. St. Kitts. West Indies. 2(5-28. Australorbis antiguensis (Sowb.). Near Quebradillas, Puerto Rico. Pilsbry Coll. M.C.Z., 103302. 29,30. Australorbis antiguensis (Sowb.). St. Kitts. M.C.Z., 74651. 31. Australorbis glabratus rejulgens (Dunker). Cotypc. Santo Domingo. M.C.Z., 83890. 32. Australorbis glabratus olivaceus (Spix and Wagner). Immature. Januaria, Brazil. M.C.Z., 74577. 33. Australorbis glabratus olivaee us (Spix and Wagner) Immature. Brazil. M.C.Z., no number. 34,35. Australorbis glabratus olivaceus (Spix and Wagner). Januaria, Brazil. M.C.Z., 74577. 36. Australorbis glabratus olivaceus (Spix and Wagner). St. Laurent du Maroni, French Guiana. Bequaert Coll. M.C.Z., 102281. Illustrations of the Anatomy and of Shells 515 PLATE 139 516 The Molluscan Family Planorbidae PLATE 140 Shells of Planorbidae 1-3. Aiistralorbis glabratus olivaceus (Spix and Wagner). Brazil. Lea Coll. LT.S.NM., 121204. 4. Aiistralorbis glabratus olivaceus (Spix and Wagner). Near Maracay, Arugua State, Venezuela. U.S.N.M., 349069. 5,6. Aiistralorbis glabratus (Say). San Juan, Puerto Rico. Bequaert. M.C.Z., 65218. 7,8. Australorbis glabratus (Say). Guadeloupe Island. Bequaert. M.C.Z., 64969. 9. Australorbis glabratus (Say). Immature. Guadeloupe Island. Bequaert. M.C.Z., no number. 10-12. Australorbis glabratus (Say). Immature. Castres, St. Lucia, W.I. M.C.Z., 72552. 13, 14. Australorbis glabratus (Say) . Young. La Juria, Tortuoguera, Puerto Rico. Henderson Coll. U.S.N.M., 535961. 15-17. Australorbis glabratus (Say). Antigua. Th. Gill Coll. U.S.N.M., 454061. 18. Australorbis glabratus (Say). Immature. Puerto Rico. U.S.N.M., 535961. 19,20. Australorbis glabratus christopherensis Pilsbrj*. Marie Galante. U.S.N.M., 390137. 21. Australorbis glabratus christopherensis Pilsbry. Franklin Estate. St. Christopher. U.S.N.M., 390136. 22. Menetus dalli F. C. Baker. Holotype. Pliocene. Caloosahatchie River, Florida. W. H. Dall Coll. U.S.N.M., 112556. 23. 24. Menetus dalli F. C. Baker. Paratypes. Pliocene. Caloosahatchie River, Florida. W. H. Dall Coll. U.S.N.M., 112556. 25. Menetus alabameiisis avus (Pilsbry). Caloosahatchie River, Florida. W. H. Dall Coll. U.S.N.M., 112556. 26. Menetus kansasensis F. C. Baker. Paratype. (90 feet deep in clay). Meade County, Kansas. U.I., P6778. 27. Menetus kansasensis F. C. Baker. Holotype. (90 feet deep in clay). Meade County, Kansas. U.I., P6778. 28,29. Menetus kansasensis F. C. Baker. Paratypes. U.I., P6778. Illustrations of the Anatomij and of Shells 517 25 28 PLATE 140 518 The Molluscan Family Planorhidae PLATE 141 Shells of Planorbidae 1. Tropicorbis pcdrinus (Miller). Rio Lope Castro, Parana, Brazil. W. L. Schmidt Coll. U.S.N.M., 365157. 2-4. Tropicorbis petencnsis Morelet. Laguna de Peten. Remate, Guatemala. U.S.N.M., 382775. 5-7. Tropicorbis denticns (Morelet). Belize, Hondm'as. A.N.S.P., 123897. 8-11. Helisoma affine. Young. Hents Bay, St. Andrew, Jamaica. U.S.N.M., 378049. 12. Helisoma jovcale (Menke). U.S.N.M., 378040. 13-18. Helisoma fovcalc (Menke). Frankfield, Clarendon, Jamaica. U.S.N. M., 400632. 19. Helisoma equatorium (Cousin). (Beach) Eben, Peru. U.S.N.M., 347900. 20.21. Helisoma equatorium (Cousin). Milagis, Ecuador. U.I., Z40572. 22,22). Helisoma equatorium (Cousin). (Labelled habiensis). Ecuador. Lea Coll. U.S.N.M., 126411. 2i, 25. Helisoma equatorium (Cousin). Quito, Ecuador. Becjuacrt. M.C.Z.. 64965. 26-28. Planorbis turgidus Jeffr. Type. 'Georgia.' (Britain in error). U.S.N.M., 65265. 29,30. Helisoma peruvianum (Brod.). Callao, Peru. (Like Clessin's figures). U.L, Z40593. 31,32. Helisoma peruvianum (Brod.) {= moricandi Beck.). Brazil. U.S.N.M., 20702. 33,34. Planorbis pedrinus Miller (= Tropicorbis) . Moll. Blatt. n.s. 1. Plate 7. 35. Planorbis boetzke.^i Miller {= Gyraulus). Moll. Blatt. n.s. 1. Plate 7. Illustrations of the Anatomy and of Shells 519 PLATE 141 INDEXES INDEX TO TEXT Since in the text of this volume all anatomical features, synonymy, distri- bution, and lists of valid species are treated in full for each genus and subgenus, references to these details are not cited in the index. Similarly, the inclusion of all taxonomic names, morphological terms, and names of authorities where these api^ear in descriptions and comparisons would ex- tend the size of the index unreasonably without adding value to the reader, hence these items are likewise omitted. A list of the more important synonyms is conveniently available in the text in a chronological list fol- lowing the heading for each group; consequently these names are not repeated in the index. For each scientific name the chief reference to the full taxonomic and morphological treatment is cited in boldface type. To avoid confusion of numerals for page, plate, and figure numbers, a separate index to the illustrations has been prepared wherein all figures are listed under the respective generic and specific names used in the explanation of the plates. abdominal ganglia 14 accessory cusps 11 acknowledgments ix Acrorbis 47, 49, 121 affinities uncertain 192 Ajroplanorbis 21, 46, 48, 86 Aguayo 22 albumen gland 6 anatomical kej's 46 anatomy, internal 4 Andrews 25 Anisopsis 48, 94 Anisus 9, 46, 48, 55 anticostianum, Helisoma anceps, n. var. 219 aorta 13 Armiger 46, 48, 75 arteries 13 arterioles 13 Atropoarmiger 78 auricle 13 Australorbis 21, 46, 48, 90 autofecundation 29 Baker, Frank Collins biographical contributions xxxv book notices and reviews xxxv memorial to xvii scientific jniblications xxv barli^chi, Hdinonin n7iceps, n. var. 219 Bnthyoniphaln.-i 46, 48, 62 bibliography' 204 biographical sketch xvii Biomphalaria 48, 89 blood flukes 21 blood sinuses 13 Boycott 29 buccal ganglia 14 buccal sac 9 Bulinidae 196 Bulinus 21, 50, 196 callus 15 Campelonn 29 Carinifex 47, 49, 154 carrefour 6 Castalia 19 central tooth 11 cephalic artery 13 cercariae 21 cerebral ganglia 14 Chadwick 29 Choanomphalus 49, 192 circulatorv system 13 Clapp 7 ' classification, history of 41 new 45 Clonorchis 21 color of shell 16 coloradocnsis, Menetus, n. sp. 230 Colton 29 columbicnsc, Helisoma, n. sp. 222 costae 16 Costorbis 48. 61 Crabb 7, 27, 29, 30, 31 crassilabris, Menetus coopcri, n. var. 230 Cristonrmigcr 78 crop 9 crystalline style 10 cubense, Helisoma caribaeum, n. var. 222 cusps, accessory 11 central 11 dalU, Helisoma cainpanulotum, n. var. 226 Menetus, n. sp. 231 Parapholyx ejfusa, n. var. 227 development 25 dextral 3 diaphragm 7 digestive sj'stem 9 523 524 The Molluscan Family Planorhidae dispersal of species 39 distribution 37 Drcpanotrema 21, 47, 49, 114 ecology 17 egg gland 6 embryological development 25 et seq. environmental conditions 17 error in generic reference 202 eupyrene spermatozoa 7 excitatory oi'gan 8 eyes 3 Fasciola 22 Fasciolopsis 22 Faust 21, 22, 24, 31 figured specimens, repositories of, 216 floridcnsis, Menetus dilatatus, n. var. 232 flukes 21 food, for other animals 19 habits 19 foot 3 foreword to Part II 215 Fossaria 22 Fossulorbis 47, 49. 118 ganglia 14 genera recognized 48 wrongly referred 202 genus new in this volume Pingielln 109 geographical distribution 38 geological history 37 gizzard 9 groups of uncertain affinities 192 growth lines 16 Gyraulus 17, 22, 46, 48. 65 haemocyanin 13 haemoglobin 13 haemol^•ml1h 13 Haldcmanina 49, 177 head 3 Helicorbis 22, 49, 106 Helisoma 47, 49, 123 anceps anticostianum, n. var. 219 anceps bartschi, n. var. 219 anceps idahoense, n. var. 220 anceps politum, n. var. 221 binneyi randolphi, n. var. 221 campamdatum dalli, n. var. 226 campanidatum pleistocenicum, n. var. 226 campanidatum rideauense, n. var. 227 caribaeum cubense, n. var. 222 columbiense , n. sp. 222 kennicotti, n. sp. 223 pilsbryi preblei, n. var. 224 subcrenatum perdisjunctum, n. var. 224 trivolvis marshalli, n. var. 225 Helisomatinae 5, 123 key to genera of, 47 hermaphrodite duct 5 Heterodiscus 48, 88 Hippeutis 47, 49, 100 hi.story of classification 41 Hoffman 22, 23 Holmes 25 hosts 21 idahoense, Helisoma anceps, n. var. 220 Indoplanorbis 196 intermediate teeth 11 internal anatomy 4 intestine 9 Intha 47, 49, 112 Jankowski 23, 54, 60. 69 jaw 10 kennicotti, Helisoma, n. sp. 223 keys to groups 46 to genera 46 et seq. to subfamilies 46 kidnev 12 Krull 31 labiatns, Menetus, n. sp. 232 lacunae 13 Lankester 25, 28 Larambergue 5, 29 Lateorbis. n. subgen. 47, 48, 85 lateral teeth 11 length of life 20 life, length of 20 lines of gi'owth 16 lingual ribbon 11 liver 9 liver fluke 22 locomotion 19 Lowrance 25, 28 Lutz 24 Lymnaea 22 Lj'mnaeidae, monograph of, ix, 16, 18, 19 male organs 4 mantle collar 3 marginal teeth 11 marshalli, Helisoma trivolvis, n. \ar. 225 Martins 24 Mattox 12. 29 memorial to Baker xvii Menetus 17, 23, 48, 49, 182 Menetus color adoensis, n. sp. 230 cooperi crassilabris, n. var. 230 cooperi planospirus, n. ^•ar. 231 dalli, n. sp. 231 dilatatus floridensis, n. var. 232 labiatus, n. sp. 232 portlandensis, n. sp. 233 mesometamorphosis 1 1 Metagonimus 21 Micromenetus, n. subgen. 48, 49, 187 migration 40 migratory birds 40 Miller 22 miracidium 21 moriihology 3 Index 525 muscular system 15 museums as repositories 216 Nautilinus 202 Nantilonrmigcr 78 nepiiridiiun 12 nervous system 14 new classification 45 new genus in this volume Pingiella 109 new species and varieties listed 218 new species in this volume Helisoma columhiensc 222 kennicotti 223 M end us coloradoensis 230 dalli 231 lab in t us 232 portlandcnsis 233 Parapholyx pusilla 229 Planorbula smithii 229 Tropicorbis shimeki 218 new subfamily in this volume Segmentininae 96 new subgenera in this volume Lateorbis 85 Micromenetus 187 new subgeneric name Syrioplonorbis 88 new varieties in this \oIume Helisoma anceps anticostianutii 219 anccps bartschi 219 anceps idahoense 220 anceps politum 221 binneyi randolpki 221 campanulalum dalli 226 campanulatum pleistocenicuni 226 campanidatum rideauense 227 caribaeum cubense 222 pilsbryi preblei 224 subcrenatum perdisjunctum 224 trivolvis marshalli 225 Menetus coopcri crassilnbris 230 cooperi planospirus 231 dilatatus floridensis 232 Parapholyx effusa dalli 227 klamathensis sinitsini 228 nidamental gland 6 nidification 25 Obstruclio 47, 48, 85 Odontogyrorbis 48, 64 oesophagus 9 Oncomelania 21 orientation of shell 15, 50 o\iduct 5 ovisperm duct 5, 6 ovotestis 6 Palaeorbis 202 Parapholyx 47, 49, 161 effusa dalli, n. var. 227 klatnathensis sinitsiiii, n. var. 228 pusilla, n. sp. 229 Paraplanorbis 49, 119 parasitic worms 21 pedal ganglion 14 penial complex 4, 7 gland 8 gland duct 5 penis 7 perdisjunctum, Helisoma subcrenatum, n. var. 224 pericardium 13 periostracum 16 Perrinilla 160 P/ii/.sa 22 Physopsis 21, 50 Pierosorna 47, 49, 134 pilasters 7 Pilsbry ix, 11, 45, 196 Pingiella, n. gen. 22, 47. 49, 109 Planorbarius 47, 49, 166 Planorbella 47, 49, 150 Planorbidae ix, 3, 17, 21, 37, 41, 45, 48 as hosts 21 Planorbijex 49. 190 Planorbinae 50 kev to genera of, 46 Planorbis 22, 46, 48. 50, 51 Planorbula 17, 48, 49. 172 smithii, n. sp. 229 Planorbulinae 172 key to genera of, 48 planospirus, Menetus cooperi, n. var. 231 Platytaphius 49, 120 pleistocenicutn, Helisoma campanulatum, n. var. 226 pleural ganglia 14 pneimiostome 3, 14 Poecilospira 49, 194 politum, Helisoma anceps, n. var. 221 Polypylis 22, 47, 49, 104 Pompholopsis 49, 165 portlandcnsis, Menetus, n. sp. 233 Potamogcton 19 preblei, Helisoma pilsbryi, n. var. 224 prei)utiinn 4, 7 Promenetus 48, 49, 178 prostate 5 pseudobranch 3, 14, 50, 196 Pseudosuccinea 22 publications of F. C. Baker xxv imlmonary siphon 14 pusilla, Parapholyx, n. sji. 229 P3'loris 9 Radix 22 radula 11, 50 randolphi, Helisoma binneyi, n. var. 221 receptacukun seminis 6 rectum 9 rediae 21 renal organ 12 rejiositories of specimens 216 526 The Molluscan Family Planorbidae reproductive system 4 respiratory system 14 rideaucnse, Helisoma campanulalum, n. var. 227 Rothschild 24 saHvary glands 9 sarcobekmi 8 Schistosoma 21 sculpture 16 Segmentina 22, 47. 48, 96 Segmentininae, key to genera of, 47 new subfamily 96 self fertilization 29 seminal vesicle 5 Seminolina 47, 49, 129 shell 15, 50 shimeki, Tropicorbis, n. sp. 218 Simroth 5 sinistral 3 sinitsini, Parapholyx klamathensis, n. var. 228 sinuses 13 siphon, pulmonary, 14 size of shell 15 smithii, Planorbula, n. sp. 229 species, dispersal of, 39 new in this volume 218 Helisoma coliimbieiise 222 kennicotti 223 Menetus coloradocnsis 233 dalli 231 labia t us 232 portlandensis 233 Parapholyx pusiUa 229 Planorbula smithii 229 Tropic.orbis shitncki 218 specimens figured, repositories of, 216 sperm duct 5 spermatheca 6 spermatophore 6 gland 8 spermatozoa 7 sporocysts 21 Stagnicola 22 Sterki 11, 19 stomach 9 style, crystalline, 10 stylet 7 stylotheca 10 subfamily new in this volume Segmentininae 96 subgenera new in this volume Lateorbis 85 Micromenelus 187 subgeneric name new in this volume Syrioplanorbis 88 Syrioplanorbis, new name 48, 88 systematic account 50 list 48 Taphius 48, 79 Taylor 5, 6 tentacles 3 Torquis 46, 48, 72 trematode worms 21 trivolvis, species allied to, 138 Trochorbis 108 Tropicorbis 17, 21, 46, 47, 48, 49, 80 shimeki, n. sp. 218 umbilicus 50 uncertain affinities 192 ureter 12 uterus 6 vagina 6 Van Cleave 29 variations 18 varieties, new 218 Helisoma ajiceps anticostianum 219 anceps bartschi 219 anceps polituvi 221 binneyi randolphi 221 campanulatum dalli 226 campanulatum, pleistocenicum 226 campamdatum rideaucnse 227 caribaeum cubensc 222 pilsbryi prcblei 224 subcrenatum perdisjunctum, 224 Menetus cooperi planospirus 231 dilatatus floriden.vs 232 Parapholyx effusa dalli 227 klamathensis sinitsini 228 vas deferens 4 velum 3 ventricle 13 verge 7 vergic sac 4, 7 visceral artery 13 ganglia 14 Vorticijex 49, 159 Ward 22 Wenz 37 Wesenburg-Lund 24 worms, parasitic, 21 INDEX TO ILLUSTRATIONS In this index, boldface type is used to refer to plate numbers; figure num- bers are in regular type. Acrorbis petricola 72:1-10 Afroplanorbis adowensis 71:10-12; 81:2 pjcifjed 71:7-9 sudanicus 81 : 3 Anisopsis calculus 81:10 loryi 81:11 Anisus leiicostomus 7:1-5; 47:15; 77:16-18 septemgyratus 7:6 spirorbis 6:5,7,13; 47:13,16; 50:25; 67:6; 77:20-22 vortex 6:1-4, 6; 47:12, 14; 77:19 Armiger crista 18:6-11; 47 : 20, 21 ; 48: 15; 50:20; 69:6; 76:6 Australorbis ajitigueyisis 139:26-30 bahie7isis 138:13-27 blauneri 138:11-12 glabratus 9:4-10; 45:1,7-11; 48:9,10; 50:13; 68:5; 77:29-31; 140:5-18 glabratus christopherensis 139:19-25; 140:19-21 glabratus olivaceus 139:32-36; 140:1-4 glabratus refidgens 139:31 guadeloupensis 137 : 35, 36 immunis 137 : 28-34 lugubris 138:1-10 paysanduensis 139:1-5 tenagophilus 139:6-18 Baihyomphalus contortus 3:5-10; 46:19, 20; 48:8; 68:1; 77:23-25 Biomphalaria smithi 81:4 Bulinus contortus 75:4-6 Carinifex jacksonen.sis 35:2-9; 49:17,18; 65:4; 115:8-13 ncwberryi 78:23,24; 112:9-11; 113:1- 23; 114:14-16 ncwberryi malleata 113:24-30 ncwberryi minor 78:25,26; 114:19-24 ncwberryi subrotunda 114:25-28 occidentalis 112:12-21; 114:17 ponsonbyi 34:1-12; 35:1; 45:2.12; 48:3; 49:19; 67:8; 114:1-13,18 Choanomphalus maacki 81:7 schrenckii 81 :9 valvatoides 81 :8 Costorbis strauchianus 76:3 Drcpanotrema ahcnum 124:21-28 anatinum 9:1-3; 68:3; 79:16-18; 124:1-13, 30 castaneo)iitens 126 :l-5 cimcx 127:1-3,7,8,16; 128:17-22 cimex pistiae 127:13-15 cultratiim 76:10; 78:17-19 cultratum anitense 126:17-19 cultratum duenasiamim 127:9-12 cultratum labrosum 128:6-10 cultratum panuco 128:1-5 depressissimum 127 : 17-19 hetcropleurus 129 : 37-42 hoffmani 10:1-9; 46:14, 15; 50:26; 68:4; 78:14-16; 126:6-12 kermatoide 126:13-16 lucidum. 11:1-7; 46:16; 48:11; 50:27; 68:2; 78:11-13; 124:29, 31, 32; 125:1-17 mellcum 125:18-21 parapseide 124:14-20 peninsularis 128:23-25 sumichrasti 128:11-16 Gyraulus albns 14:1-11; 48:13; 50:28; 68:9; 70:13; 77:1-3; 136:1-3 borcalis 126:32-39 circumstriatus 17:1-5; 47:2,6; 50:22; 52 : 14-16 convexiusculus 19:1-3; 47:8,17 deflectus 136:13-21, 23-26 dcflectus obliquus 16:1-15; 47:3,10; 50:18; 69:2; 136:22,27-31 hirsutus 15:1-7; 47:18,19; 50:17; 69:1; 70:5; 136:4-12 latestomus 19:4-9; 47:11 parvus 17:6-12; 47:1,5; 48:14; 50:16; 69:3; 77:4-6 similaris 18:1-5; 47:9; 69:4 vermicularis 15:8-10; 47:4,7; 50:19; 69:5 Helicorbis umbilicalis 78:5-7 Helisoma afflne 141:8-11 ammon 89:25-27; 94:14, 15, 17, 20-28; 95:1-16 anceps 22:10,12; 23:1-4, 7-11; 44:1,7; 48:17; 49:1; 53:1-3; 80:1-6; 82:1-19, 26, 30; 84:1; 96:23-30 anceps a7iticostianum 96:18-22 anceps aroostookensc 83:27-29 anceps bartschi 83:19-22 anceps cahni 54:3; 85:14-16 anceps corrugatum 82:31 anceps idahoense 84:26-28; 101:11, 12 anceps jordanensc 84:6-8 anceps latch fordi 22:1; 23:5, 6; 44:8; 54:4; 85:5-7 anceps minnesotense 82:27-29 anceps percarinatum 22:2-4, 11; 54:1; 84:2; 85:8-13 anceps politum 83:16-18 anceps portagensc 84:3; 85:1-4 anceps royalense 54:2; 84:4, 9, 13-17 anceps rushi 84:10-12 527 528 The Molluscan Family Planorbidae Helisoma (continued) anceps saiji 53:4; 82:32-34; 83:1-6; 84:5 anceps shellense 82:23-25 anceps striatum 82:20-22 anceps unicarinatinn 83:7-15 binneyi 93:19-26; 94:9-13, 16. 18, 19 binneyi randolphi 94:1-8 caloderma 115:2-4 campanulatum 27:1-14; 62:1; 70:1; 80:16-19: 108:1-17; 109:1-6; 111:21. 22 campanulntum canadense 62:3; 110:11-20 campanulatu m coUinsi 1 10 :27-35 ; 111:17-20 campanulatum dalli 111:12, 13. 15, 16 campanulatum ferrissi 108:18-34 campanulatum michigancnse 111:6-11, 14 campanulatum pleistocenicum 110:21- 26 campamilatuni rideauense 109:21-24 campanulatum rudentis 111:1-5 canipnnulntnm --imithi 49:11. 20; 62:4 109:14-20. 25; 110:5-10 campanulatiun wisconsinense 45:15-17 62:2; 109:7-13; 110:1-4 caribaeum 99:31; 100:1-17; 101:15 115:1 caribaeum cubcnse 119:22-25 caribaeum, guatemaleuse 99:20-24, 32- 36 chautauquen.se 29:19-22; 55:5; 86:16- 19 columbiensc 119:16-21 conanti 106:4-7 contrerasi 102:2-4 corpulentum 31:1-7; 44:3. 15; 49:15 57:3; 106:17. 22; 107:1-7, 13 corpulentum multicostatum 31:8-13 44:16; 58:3; 106:16; 107:12, 16-21 corpulentum vcrmilionensc 31:14-18 58:2; 107:8-11, 14 costaricense 101:8-10 disstoni 106:8. 12-15 duryi 33:11. 13, 14; 103:20-31; 104:1-7 duryi eudiscus 33:1-7; 52:9-11; 63:4; 105:14-19 duryi intercalare 105:4-13 duryi normale 33:8-10, 12, 15-19; 44:5, 26; 49:14; 52:6-8, 12; 64:3, 4; 80:11, 12; 104:8-22; 105:1-3 duryi preglabratum 105:20-27 duryi seminole 80:9; 102:21-23; 103:1-19; 106:1-3; 111:23; 112:1-8 equaiorium 141:19-25 eucosmius 84:18-21 eucosmius vaughani 84:22-25 eyerdami 115:5-7 foveale 101:1-5; 141:12-18 horni 26:1-5: 44:23; 49:9; 60:7; 90:19-21: 92:13-16 kennicotti 89:13-17 magnificum 31:20-22; 44:13; 49:16; 57:4; 96:31-34; 101:7' fnultivolvis 80:19-21; 109:26-29 occidentale 32:9, 10; 44:18; 49:13; 61:1; 89:23, 24; 93:4-15 occidentale dcpressum 93:16-18 oregonense 28:1-5; 44:6; 49:6; 61:3; 96:1-12 peruvianum 141 : 29-32 pilsbryi 25:1-7; 44:12; 49:5; 56:3; 88:8-10; 91:5 pilsbryi injracarinatum 25:8-13; 44:17; 49:8; 56:4, 5; 88:11-16 pilsbryi preblei 91:6-8 plexatum 30:1-9; 44:22; 49:10; 58:4-6; 59:1,2; 89:22; 92 •17-23" 93 '1-3 sea/are 28:6-14; 44:4, 25; 49:4; 51:1- 14; 52:1-3; 64:1. 2; 70:2, 3; 80:7, 8; 102:11-20; 111:23-31 subcrenatum. 30:10-19; 32:8; 44:21; 49:7; 59:5; 60:1-3; 61:2; 70:12; 89:18-20; 91:9-19; 92:1-12; 101:13, 14 subcrenatum disjectum 89:21; 90:13-18 subcrenatum perdisjunctum 96:13-17 tenue 97:1-11 tenue applanatum 97:26-28; 98:1-13; 99:1-3; 101:16 tenue bourcardi 97:12-17 tenue calif orniense 32:1-7; 44:24; 45:4-6; 50:1; 59:3, 4, 6; 63:3; 98:16-24. 26; 99:11-15 tenue chapalejise 102:1, 5-10 tenue exaggeratum 99:18-25 tenue sinuosum 97:14, 15. 25; 99:4-10 tenue strebelianum 99:16-19, 25-30 ^rasHi 32:11-17; 44:20; 49:12; 52:13; 60:4-6; 95:17-25 trivolvis 24:1-15; 44:2.9; 48:1. 2, 18; 49:2; 55:1. 2, 4; 70:6; 80:13-15; 85:17-30; 86:1-4, 20, 21; 88:1-3; 89:28. 29 trivolvis jallnx 29:17, 18; 63:1; 70:8; 87:1-10 trivolvis holstonense 87:17-24 trivolvis intertcxtum 86:9-15. 23; 89:5-8 trivolvis lentum 29:7-13; 44:11; 52:4, . 5; 55:3, 6, 7; 63:3; 86:5-8, 22; 89:1-4, 12 trivolvis macrostomum 29:14-16; 44:10; 56:2; 70:7; 88:4-7 trivolvis marshalli 87:11-16 trivolvis pseudotrivolvis 29:1-6 trivolvis reticulatum 89:9, 10 truncatuyn 26:6-13; 44:13; 49:3; 57:1, 2; 89:11; 90:1-12 lumens 100:31-37 Index 529 Hclisoma (continued) whiteavesi 31:19; 58:1; 106:18-21; 107:15 winsloici 56 : 1 ; 91 : 1-4 wyldii 100:21-30 UHjkUi mlvini 100:18-20 Hippeuiis coinplnnatus 2:7-15; 46:17, 18; 48:12; 79:4-6 fontanus 79:4-6 hidoplanorbif! rxustiis 21:1-10; 22:5-9; 45:19; 50:10; 66:1; 73:1-3; 74:6-9; 79:33-35 Iiitho capitis 8:1-8, 11; 47:26, 27; 50:23; 69:9 Isidora globow 71:1-6 Menctus alabamensis 121:34, 37-39; 123:12, 13 alabamensis avm 121:40, 41; 123:1; 140:25 brogniartianus .121 : 42-44 centervillensis 121:1-8 coloradoensis 122:23-25 cooperi 39:7, 8; 120:11-18, 22, 27, 28; ^ 122:1,2,7 cooperi calliogh/ptufi 38:3, 11-15; 39:1- 6, 9, 10; 46:7, 8; 50:7; 67:3; 120: 19-21; 122:8 cooperi craftssilabrii^ 121:19-21; 122:13; 123:26 cooperi multilincatus 120:23-26, 29-31; 122:9-12 cooperi planospirus 122:3-6 dnlli 140:22-24 dilatatus 40:3-5, 7, 9, 12; 46:5. 6; 50:9; 67:4; 70:9, 10; 79:13-15; 121:22, 25,26 dilatatus buchanensis 121:23, 24, 27-31, 33 dilatatus floridanus 123:20-22 dilatatus pennsylvaiiicus 121:32, 35. 36 kansasensis 140:26-29 labiatus 121:9-11 opercularis 38:1. 2, 4-10; 79:22-24; 120:1-10 portlandensis 121:12-18 sampsoni 40:1, 2. 6. 8, 10. 11; 50:6; 67:5; 123:11. 14-16. 31-33 'uligi)}osus 123:23-25, 27. 28 Odontogyrorbis kratnbergcri 76:1. 2 Parapholyx effusa 78:20-22; 116:1-6 efjusa costata 115:24-26; 116:12-14 effusa dalli 115:27-30 effusa diagonalis 36:10; 50:5; 116:15-17 effusa klamathensis 36:1-9. 11, 12; 46:1, 2; 50:4; 65:3; 115:14-23 effusa neriloides 116:7-11 klamathensis sinitsini 123:2-10 mailliardi 116:27-30; 117:27-30 nevadensis 117:7-26 pusilla 117:1-6 solida 116:18-24 solida optima 120:32 Paraplanorbis condoni 81 :5 Perrinilla cordilleriana 79:31, 32 Pingielln peipinensis 4:1-9; 5:1,5; 78 : 8-10 Planorbarius corneus 20:1-13; 45:18; 50:14; 66:2; 80:22-24 Planorbijex vanvlecki 81:6 Planorbis adoivensis 71 : 10-12 boelzkesi 141 : 35 pfeifferi 71:7-9 krambergeri 76:1 planorbis 1:1-9; 46:9, 10; 48:6, 7; 50:21; 67:7; 77:26-28 turgidus 141:26-28 Planorbula armigcrn 37:1-12; 45:3, 13; 50:2; 65:1;' 76:8; 79:25-27; 118:1, 9, 13-15, 16-19, 26, 31 armigera indianensis 118:4; 119:1-3 armigera palustris 118:2 Christ yi 119:13-15 crassiiabris 118:3. 20-25. 32 jenksii 50:3; 65:2; 70:11; 118:5. 10, 27-30: 119:4-6 smithi 118:6. 11, 12; 119:10-12 ivheatleyi 76:9; 79:28-30; 118:7, 33; 119:7-9 Platytaphius heteropleurus 79:10-12 Poecilospira trochijormis 81:1 Polypylis calathus 69:8 hemisphaerula 5:2-4, 6, 7; 8:9, 10; 47:24, 25; 76:5; 79:7-9 largilUarti 79:7-9 Pompholopsis whitei 76:11 Promenetus exacuous 41:1-10; 42:1, 3, 7. 12; 46:3. 4; 48:4, 5; 50:8; 67:1; 122:14-19, 26-28 exacuous megas 42:2, 4, 5, 8-11, 13; 79:19-21; 122:20-22 hudsonicus 123:17-19 imus 123 :29. 30 rubellus 123:37-39 umbilicatcllus 42:6; 43:1-12; 50:15; 67:2; 123:34-36 Segmenlina nitida 2:1-6; 3:1-4; 47:22, 23; 48:16; 50:24; 69:7; 76:4; 79:1-3 Taphius andvcolus 77:13-15; 131:32-35; 137:1-13 andecolus niontanus 131:27-31 montanus 137:25-27 pronus 137:14-24 subpronus 131 : 36-40 Tropicorbis albicans 134:4-6. 15-19, 29 bourcardianus 132:31. 32; 135:7-19 canonicus 135:20-27 centimetralis 130:30-37; 135:5-8 chile7isis 131:12-14; 135:9-11 530 The Molluscan Family Planorbidae Tropicorbis (continued) decipiens 131:6-11 declivis 133 :25-27 dentiens 141 : 5-7 denlijerus 134:8, 9 fieldi 132:24-30 gradient lift 130:1-12; 135:32-35 gimdlachi 132:33-35 hnvanensis 12:1-11; 46:13; 68:8; 70:4; 130:18-28 heloicus 133:10-13 isthmicus 131 : 1-7 janeirensis 133:18-21; 134:24 kuhnianus 132:6-9 maya 130:13-17 melleus 78:1, 2 meridaemis 132:22. 23; 135:14-16 nigrilabris 78:3, 4; 133:14-17; 134:25 obstriictus 13:1-3; 50:11; 68:7; 76:7; 128:26-33; 129:4, 8, 9; 133:28-35; 134:10, 11, 22 obstructus a7iodontus 133:36-40 obstructus donbiUi 129:17-25; 131:15- 26; 135:21, 23 obstructus dunkrri 129:26-36 orbiculus 77:7-9; 129:1-3, 5-7, 10-16 palUdus 77:10-12; 132:1-5 paparyensis 134:1-3, 20, 26 pedrinus 141:1, 33, 34 peregrinus 130:38-41; 135:1-4 petenensis 133:1-3; 141:2-4 philippianus 130:29-34; 135:12, 13 riisei 13:4-10; 46:11, 12; 50:12; 68:6; 132:15-21 schrammi 133:22-24; 134:7,27 shitneki 134:12-14, 28 stramincus 132:10-14 tepicensis 133 :4-9 trigyrns 135:28-31 Vorticifex binneyi 76:13 tryoni 76:12