ILLINOIS BIOLOGICAL MONOGRAPHS Vol. IV April, 19 1 8 No. 4 Editorial Committee Stephen Alfred Forbes William Trelease Henry Baldwin Ward Published under the Auspices of the Graduate School by THE University of Illinois Reprinted with the permission of the University of Illinois Press JOHNSON REPRINT CORPORATION JOHNSON REPRINT COMPANY LIMITED 111 Fifth Avenue, New York, N.Y. 10003 Berkeley Square House, London, W. 1 Copyright, 1918 by the University of Illinois Distributed May 31, 1919 First reprinting, 1967, Johnson Reprint Corporation Printed in the United States of America NORTH AMERICAN PSEUDOPHYLLIDEAN CESTODES FROM FISHES WITH THIRTEEN PLATES BY ARTHUR REUBEN COOPER Contributions from the Zoological Laboratory of the University of Illinois under the direction of Henry B. Ward, No 127 COPYRIGHT, I9I9 BY THE UNIVERSITY OF ILLINOIS TABLE OF CONTENTS Pages Introduction 7 Historical Data 8 Explanation of Terms 10 Key to the Families, Subfamilies, Genera and Species 11 Order PSEUDOPHYLLIDEA 13 Family DIPHYLLOBOTHRIIDAE 15 Ligulinae Ltihe 1899 16 Ligula Bloch 1782 17 Ligula inlestinalis (Linnaeus 1758) 18 Schistocephalus Creplin 1829 30 Schistocephalus solidus (O. F. Miiller 1776) 30 Haplobothriinae Cooper 1917 42 Haplobothrium Cooper 1914 43 Haplobothriiim globuliforme Cooper 1914 44 Cyathocephalinae Liihe 1899, e. p 53 Cyathocephalus Kessler 1868 53 Cyathocephalus americanus Cooper 1917 53 Bothrimonus Duvernoy 1842 62 Bothrimonus intermedins Cooper 1917 63 Marsipometrinae Cooper 1917 70 Marsipometra Cooper 1917 70 M arsipometra haslata (Linton 1897) 71 Triaenophorinae Liihe 1899 81 Triaenophorus Rudolphi 1793 81 Triaenophorus sp. larv 82 Fistulicola Liihe 1899 88 Fistidicola plicatus (Rudolphi 1819) 89 Family PTYCHOBOTHRIIDAE 93 Ptychobothriinae Liihe 1899 94 Bothriocephalus Rudolphi 1808 95 Bothriocephahis scorpii (Miiller 1776) 96 Dibothrium anguslalum (Rudolphi) 112 Bothriocephalus claviceps (Goeze 1782) 114 Bothriocephalus cuspidatus Cooper 1917 123 Bothriocephalus manubriformis (Linton 1889) 133 Dibothrium laciniatum (Linton) 145 Bothriocephalus histiophorus (Shipley) 147 Bothriocephalus occidentalis (Linton 1898) 149 Clestobothrium Liihe 1899 153 Cleslobothrium crassiceps (Rudolphi 1819) 154 Amphicotylinae Liihe 1902 I'l Abothrium van Beneden 1871 I'l Abothrium rugosum (Batsch 1786) 1'2 Abothrium crassum (Bloch 1779) 186 2941 ILLINOIS BIOLOGICAL MONOGRAPHS 6 Bibliography 201 Explanation of Plates 211 Index of Hosts 237 Index 241 295] PSEUDOPHYLLIDEA FROM FISHES— COOPER INTRODUCTION Soon after commencing the study of Haplobothrhim glohuliforme Cooper the writer (1914, 1914a) saw that, apart from the early and somewhat brief reports and descriptions by Leidy and the later, but yet pioneer work of Linton on both marine and fresh-water species, very little had been done on the mem- bers of the order in America. Consequently the desire for an opportunity to work up other species which had in the meantime been collected at the Canadian Lake Biological Station on Georgian Bay, located at Go-Home Bay, Muskoka District, Ontario, and at the Marine Biological Station at St. And- rews, New Brunswick, grew with the feeling that something of a comprehensive nature ought to be undertaken in order not only to ascertain to what extent European species are to be found in this continent, but also to locate properly in the classification at least some of the new forms formerly described, especially by Linton. Altho the material then at hand was investigated to a certain extent at the University of Toronto, it was not until the writer came to the University of Illinois that it was studied at all thoroly with the aid of other material for comparison from the collection of the University of Illinois, under the care of Professor Henry B. Ward. Supplementary material, which in many cases was all that was available, was obtained by Professor Ward from the United States National Museum and the Bureau of Animal Industry, but apart from a few vials no European specimens could be procured, owing to the present international conflict. On account of the lack of the latter most of the determinations have been made with the aid of the literature only, a fact which the writer feels may necessitate future changes in connection with a few species which have been more or less tentatively regarded to be the same as those in Europe. In all cases, however, the specific details of the American forms have been emphasized, so that if changes have to be made later, the basis for such will be at hand. The writer would like to point out in this connection the comparative lack from a systema- tic standpoint of adequate descriptions of many of the European species which have been known for many years. It was this fact which in the absence of the original material for comparison made the present work one attended with not a little difficulty. In the main the classification of the order adopted by the writer is that proposed by Liihe (1902) and later (1910) retained with only a few modifica- tions. The family of the Caryophyllaeidae is, however, not included, so that the order is considered to be rather that of Carus (1863), with Luhe's later conceptions of the other families. One of the latter must now again be modified considerably owing to the present study of two quite aberrant species, namely, Haplobothrium globulifonne Cooper and Marsipometra hastata (Linton) which have been found by the writer to be very disturbing to the classification. The writer wishes here to tender his thanks in the first place to the Biological Board of Canada for placing means and faciUties at his disposal in connection 8 ILLiyOIS BIOLOGICAL MONOGRAPHS [296 with his earlier collecting at the above-mentioned Canadian Biological Stations; to the University of Illinois for the opportunity of collecting further material at the Marine Biological Laboratory at Woods Hole, Massachusetts, and at the Harpswell Laboratory, South Harpswell, Maine, during the summer of 1916, and to the staffs of these institutions as well as to that of the Marine Laboratory of the United States Bureau of Fisheries at Woods Hole for assis- tance and direction in connection with the same; to the Smithsonian Institute and the Bureau of Animal Industry, from whom valuable material was obtained for comparison, in the latter case thru the kind offices of Dr. C. W. Stiles of the Hygienic Laboratory, Washington; and to the following investigators for alcoholic specimens: Professor O. Fuhrmann, University of Neuchatel, Switzerland, Professor Edwin Linton, Washington and Jefferson College, Pro- fessor E. M. Walker, University of Toronto, Dr. H. J. VanCleave, University of Illinois, Dr. G. R. LaRue, University of Michigan, Dr. A. S. Pearse, Univer- sity of Wisconsin, and Messrs. H. R. Hill and R. P. Wodehouse. Finally to Professor H. B. Ward the writer wishes to express his sincere indebtedness not only for the use of his extensive private library and collections and for the procuring of rare books and specimens, but for his constant and stimulative interest in, and valuable criticism of, the work which has resulted in the following paper. HISTORICAL DATA Apart from Gmelin's (1790) collecting together the data given by the older writers such as Linnaeus, Pallas, Miiller, Goeze, Bloch, Fabricius, Batsch, Schrank and Abildgaard, and Zeder's (1800, 1803) treatises, the first most important work on the bothriocephalid cestodes was the Entozoorum Hisloria Naturalis by Rudolphi (1808-1810). In this he reviewed the earlier literature, making valuable comments on the same, and described species of Ligula, Triaenophorus and Bothriocephalus, the latter name being used for the first time. WTiile Lamarck (1816) dealt with only the more common species, Rudolphi in his second work of major importance, the Entozoorum Synopsis (1819), made some corrections of his earlier publication and further contribu- tions in the way of a few new species. F. S. Leuckart (1819), who did not receive Rudolphi's Entozoorum until after his own work was in print, dealt only with species of the genus Bothriocephalus as conceived by Rudolphi, which then con- tained members not only of the Pseudophyllidea but also of the Tetraphyllidea and the Trypanorhyncha. Nitzsch (1824) briefly defined the species of the same genus, while later Creplin (1839) dealt with them more in detail and erected the new genus Schistocephalus. Drummond (1838) was one of the first to report bothriocephalids from the British Isles, while BeUingham (1844) and Thompson (1844) made further contributions, all three dealing with forms from Ireland. Eschricht (1841) pubhshed some of the earliest data on the internal anatomy of the group, and Kolliker (1843) made a study of the development of the eggs of a few species. The next and perhaps most impor- tant work was that by Dujardin (1845) who, while following Rudolphi in the 297] PSEUDQPHYLLIDEA FROM FISHES— COOPER 9 main, made many valuable additions from original observations. Van Beneden (1849, 1850) first essayed to erect a more comprehensive classification than had hitherto been used, and Diesing (1850) went much farther in his Subtribe I, Gymnobothria, of Tribe IV, Bothriocephalidea, of Suborder I, Aprocta, of Order IV, Cephalocotylea. Baird (1853) reverted to Rudolphi's brief system, in listing forms from the British Museum. Wagener in two papers (1854, 1857) pubHshed studies on the development which even to-day are models of careful work and excellent illustrating. Leidy (1855, 1856) was the first to report forms from America, while Weinland (1858) made a few references to bothriocephalids. Then, until Diesing (1863) re\dsed his classification nothing of systematic importance appeared. Olsson (1867) was one of the first to report species from the Scandinavian countries; later (1876, 1893) he made further contri- butions from the same region. After Willemoes-Suhm's (1869) studies on the development of Schistocephalus dimorp/ius, came Duchamp's (1876) and Donnadieu's (1877) classical experiments on the life-histories of the ligules. Linstow (1878) brought together in a list the forms known up to that time. A few years later Fraipont (1880, 1881) published studies on the excretory system of a number of species which even to-day are perhaps the most impor- tant contributions in that direction. The nervous system was made the object of special inquiry by Lang (1881), while later it was dealt with more at length by Niemiec (1888) and Cohn (1898). After a period in which such works as those with studies on development by Moniez (1881), Zschokke (1884) and Schauinsland (1885) are prominent, come the next reports of species from America, namely, those contained in Linton's first paper (1889). The latter was followed by a second (1890), containing extensions of the first, and later by others (1891, 1897, 1901 and 1901a) dealing with a variety of forms from marine and fresh-water fishes. Further anatomical studies by Lonnberg (1891), Kraemer (1892), Matz (1892) and Zernecke (1895) lead on to Monticelli's (1892) classification, which was the most important since, the time of Diesing, altho Perrier (1878) had in the meantime voiced his ideas along that Hne. The next in order is Ariola's (1896) division of the family "Bothrio- cephaUdae, " in which incidentally were yet to be found errors regarding the position of the bothria. Beginning with 1894 and continuing to 1900 there was in progress the publication of Braun's Cestodes in Bronn's Tierreich, which is by far the most comprehensive work on the group, since it brings together the substance of the most important of the earlier works on the morphology as well as the system of the order. One of the first papers by Liihe, who did recent important work on the group, was that (1896) in which he dealt with the nervous system of Ligula. Further study led him to pubHsh a few years later (1899) his first classi- fication, which was adopted by Braun (1894-1900). In the meantime Lonn- berg (1897) made valuable contributions to the knowledge of the phylogeny of the parasitic flatworms; while Gamble (1896) and Perrier (1897) had erected systems of classification which, however, do not have nearly as much in their 10 ILLINOIS BIO LOGIC A L MONOGRA PHS [298 favor for general acceptance as does that by Luhe. In 1900 Ariola brought out his revision of the family of the BothriocephaUdae, which, however, was shown by Liihe (1901) to be rather of the nature of a compilation, in- volving at the same time several omissions, than a distinct advance in our knowledge. In 1901 there appeared in Lankester's Treatise on Zoology Benham's classification of Cestodes which professedly follows the earlier works of Railliet and Blanchard. Luhe's (1902a) revision of the bothriocephalid system comes next in order. It is this newer system, only sUghtly modified in 1910, that is accepted by the writer with several necessary modifications which are dealt with below. From 1902 until Die Susswasserfauna Deutschlands was published, the literature on the group consists mostly of papers on individual species or mere listings. Spengel's (1905) paper on Die Monozootie der Cestoden ought, however, to be mentioned, since it is one of the latest discussions of a question which occupied a good deal of the attention of many of the older writers. Finally Ward (1910) and the writer (Cooper, 1914a, b) made the latest addi- tions to the American Uterature, while Stiles and Hassall won the gratitude of the younger workers at least by their pubUcation of the section of the Index- Catalogue of Medical and Veterinary Zoology on Subjects: Cestoda and Cestodaria which the writer has found of inesthnable value in the pursuit of his studies. EXPLANATION OF TERMS Owing to the fact that not a little confusion exists in the earliest literature regarding the terms of orientation used for the cestode body, the writer wishes here to explain those that will be employed in the specific descriptions below. Even much later than the time of Diesing (1850) the word "lateral" was used to refer to the flat surfaces of the typical strobila, while "marginal" was and is even yet perfectly clear in meaning; but from the standpoint of bilateral s}Tnmetry both words may mean the same thing. Here they are considered to be synonymous and are used to refer to any part which is situated in or at the edges of the strobila and consequently of the individual proglottides. On the other hand, the word "surficial" is adapted from geology to take the place of the word " flachenstandig " which is used freely in Luhe's papers to mean that the structures in question are located on the broad, flat surfaces of the chain. As is customary, the latter are considered to be dorsal and ventral in position, the ventral surface being that which is nearer the isthmus of the ovary. The end bearing the scolex is called the anterior end and the opposite, the posterior end, despite differences of opinion as to which is which. For the sake of brevity the words, "length," "depth" and "breadth" (or "width") are used instead of the longer terms, diameters in the longitudmal, in the dorsoventral and in the transverse directions, respectively, exceptmg where the organ in question, e.g., the transversely elongated cirrus-sac of the Triaenophorinae, is so shaped that it would be confusing to speak of its obvious length as its width. Otherwise the usual terms of orientation are employed. 299] PSEUDOPHYLLIDEA FROM FISHES— COOPER 11 KEY TO FAMILIES, SUBFAMILIES, GENERA AND SPECIES or PSEUDOPHYLLIDEA FROM FiSHES DESCRIBED IN THIS PaPER 1 (14, 15) Eggs with thick shells and opercula. Opening of cirrus and vagina on the same surface as that of the uterus and ahead of it or marginal. Family DIPHYLLOBOTHRIIDAE Liihe 1910 . . 2 2 (11) Opening of cirrus and vagina surficial 3 3 (8) Genital openings always on the same surface of the strobila . . 4 4 (7) Scolex very short, not distinct from the strobila. Subfamily LIGULINAE Luhe 1899 .. 5 5 (6) Segmentation confined to the anterior end, or (in larvae) absent Ligula Bloch 1782 Type and only species: L. inteslinalis (Linnaeus 1758) , . p. 18 6 (5) Segmentation complete even in the larval stages. Schistocephalus Creplin 1829 Type and only species. Schistocephalus sc'Hdus {O.Y.MuWex 1776) . ... p. 30 7 (4) Scolex (secondary, see below) similar in shape to the first proglottis ; no neck; segmentation beginning immediately behind the scolex, but confined to the anterior end of the worm. Subfamily HAPLOBOTHRIINAE Cooper 1917 . . p. 42 Type and only genus . . Haplobothrium Cooper 1914 . , p. 43 Type and only species: H. globuliforme Cooper 1914 . . p. 44 8 (3) Genital openings of different segments not on the same surface, but alternating irregularly from one surface to the other. External segmentation little expressed. Subfamily CYATHOCEPHALINAE Liihe 1899 .. 9 9 (10) Scolex an unpaired, terminal, funnel-shaped organ. Cyathocephalus Kessler 1868 Only American species: C. americanus Cooper 1917 . . p. 53 10 (9) Scolex with two almost spherical bothria, the apertures of which may be separated or more or less completely fused to form a single terminal opening .... Bothrimonus Duvernoy 1842 Only American species: B. intermedius Cooper 1917 , . p. 63 11 (2) Opening of cirrus and vagina marginal. Subfamily TRIAENOPHORINAE Liihe 1899 . . 12 12 (13) Scolex armed with four three-pointed hooks. Triaenophorus Rudolphi 1793 Only larval forms of two specific types present p. 82 13 (12) Scolex sagittate, or replaced by a pseudoscolex. Segmentation strongly expressed, the individual proglottides very short with leaf-like free lateral portions Fistulicola Liihe 1899 Only American species: F. plkahis (Rudolphi 1819) ... p. 89 12 ILLINOIS BIOLOGIC A L MONOGRA PES [300 14 (1, 15) Eggs with thin shells and no opercula. Opening of cirrus and vagina marginal, that of uterus at the same level or slightly behind it and ventral. Segmentation very distinct and regular. Subfamily MARSIPOMETRINAE Cooper 1917 . . p. 70 Type and only genus: Marsipometra Cooper 1917 . . p. 70 Type and only species: M. hastata (Linton 1898) . . p. 71 15 (1, 14) Eggs with thin shells and no opercula. Opening of cirrus and vagina dorsal and behind the ventral uterus-opening, or marginal in which case sementation is not well expressed. Family PTYCHOBOTHRIIDAE Luhe 1902 . . 16 16 (27) Opening of cirrus and vagina surficial. Subfamily PTYCHOBOTHRIINAE Luhe 1899 . . 17 17 (26) Scolex elongated, with prominent terminal disc. Segmentation well developed, neck absent. Bothriocephalas Rudolphi 1808 . . 18 18 (23) Scolex not pronouncedly constricted posteriorly 19 19 (20) Uterus-sac occupies one-sixth of the transverse diameter of the proglottis B. scorpii (Miiller 1776) . . p. 96 20 (19) Uterus-sac occupies one-third of the transverse diameter of the proglottis 21 21 (22) Scolex small B. clavkeps (Goeze 1782) . . p. 114 22 (21) Scolex large, terminal disc deeply notched surficially, sagittate in lateral view B. cuspidahis (Cooper 1917) . . p. 123 23 (18) Scolex constricted posteriorly 24 24 (25) Terminal disc deeply notched laterally as well as surficially; vagina provided with a bulbous sphincter near its opening . . . . B. manubriformis (Linton 1889) . . p. 133 25 (24) Terminal disc rectangular; no vaginal sphincter B. occidentalis (Linton 1898) . . p. 149 26 (17) Scolex almost spherical; walls of each bothrium fused to form a hollow organ of attachment with a small anterior opening Clestobothrium Liihe 1899 Type and only species: C. crassiceps (Rudolphi 1819) . . p. 154 27 (16) Opening of cirrus and vagina marginal. Subfamily AMPHICOTYLINAE Luhe 1902 . . 28 Onlygenus represented Abothrium van Beneden 1871, 28 (29) Pseudoscolex in adult. Longitudinal muscles in bundles. Vitelline follicles entirely within the longitudinal muscles. A. rugosum (Batsch 1786) . . p. 172 29 (28) Scolex typical, but variously shaped. Longitudinal muscles not in bundles. Vitelline follicles am.ong the longitudinal muscles or outside of them A. eras stm (^Xoch. Ill 9) . . p. 186 3011 PSEUDOPHYLLIDEA FROM FISHES— COOPER 13 Order PSEUDOPHYLLIDEA Carus 1863, nee Luhe 1910, e. p. Polyzootic cestodes with mostly unarmed scolex without rostellum or pro- boscis formation, excepting in the Haplobothriinae where the primary scolex is provided with four protrusible proboscides resembling those of the Try- panorhyncha. Usually with two weakly developed sucking grooves, which in individual cases are modified by the strong development of their walls or by more or less extensive fusion of their edges, so that they may appear funnel- shaped or tubular, which may also unite with each other more or less com- pletely to form an unpaired terminal adhesive organ, or become rudimentary or entirely absent, in which latter case they are replaced by a terminal function- al organ of attachment. The development of a pseudoscolex takes place occa- sionally. External segmentation more or less pronounced, only seldom com- pletely absent. Genitalia in each segment usually single, seldom double. Their development proceeds from ahead backwards and does not continue to a degeneration of the reproductive glands; but the majority of the pro- glottides, being at the same stage of development, bring their sexual products to maturity at the same time, so that in all of them new eggs are formed con- tinuously and all the eggs of the whole animal are at the same stage of embryon- ic development. A surficial opening of the uterus is always present. Testes numerous; vas deferens strongly coiled, without a true seminal vesicle. Ovary near the posterior end of the proglottis, mostly median in the case of single genitaUa, seldom approaching the margin of the strobila bearing the genital opening (that of the cirrus and vagina). Vitelline follicles very numerous, mostly in the cortical, seldom in the medullary parenchyma. Uterus a more or less winding canal, the individual coils of which converge somewhat towards the centre of the proglottis to form the so-called rosette; but in other forms it enlarges to form a capacious cavity, the uterus-sac, from which the duct-like beginning of the uterus is sharply separated. Eggs oper- culate or non-operculate, developing mostly only after being laid, but in other cases within the uterus. The above diagnosis of the order is that of Liihe (1910:11), minus the family Caryophyllaeidae and partly emended to accommodate the subfamily Haplo- bothriinae, in which what is here considered to be the true (or primary) scolex is deprived of bothria but provided with four eversible proboscides quite comparable in structure to those of the order Tr\^anorhyncha. It is evident that what was formerly (Cooper, 1914, 1914a) called the scolex of Haplo- bothrium cannot now be considered to be a true scolex but only the foremost segment of the adult or secondary strobila, which is indicated by its resem- blance internally as well as externally to the segments immediately following. Whether or not a pair of bothria were originally present or are present in the very earliest stages, whether such bothria have become modified into the pro- boscides, or whether the latter have developed from four separate "accessory 14 ILLINOIS BIOLOGICAL MONOGRAPHS [302 suckers" as believed by Pintner (1880) to be the case in the Trypanorhyncha, must remain mere suggestions for the present. Furthermore as to the forma- tion of segments there are in Haplobothrium not only conditions quite similar to those in Bothriocephalus s. str. and other genera in which there is no neck, segmentation beginning immediately behind the scolex, but those reminding one of the proUferation of scolices in echinococcus. In the former, as will be seen below where the process is described more in detail (p. 102), a primary se^mient divides up into secondary segments, these into tertiary segments, and so on until there may be eventually thirty-two or more genital segments corresponding to one primary segment formed immediately behind the scolex. In Haplobothrium a primary strobila divides up into primary segments, these subdivide into secondary segments, the definitive joints of the ordinary stro- bila met with, which in turn may be subdivided again and evidently indefinitely to form new chains. The chief difference between these two cases is one of degree of regularity in the subdivision. Whereas in Bothriocephalus the whole anterior region of the worm is affected, evidently no division taking place after the rudiments of the reproductive organs have become separated from the common rudiment, and the subsegments remain attached to one another, in Haplobothrium not only do the primary segments separate as secondary strobilas, but in the latter only a limited region is involved in further sub- division. On the other hand there is somewhat of a resemblance between this manner of subdivision in Haplobothrium and that of the larval Echinococ- cifer in that the strobilas are developed from an original "nurse." That is, the primary strobila of the former might be looked upon as a nurse from which are developed segments, comparable to the daughter-cysts of an echinococcus, which in turn produce (secondary) scolices and eventually strobilas. In other words there might be recognized at first sight a sort of alternation of generations in the case of Haplobothrium. But this comparison is only a superficial one, for as will be shown below (under Haplobothriinae) the secondary scolex cannot be considered to be a true scolex nor the secondary strobila a true strobila; but the primary strobila with its four proboscides must be regarded as such. Finally, this peculiar method of segmentation reminds one of the asexual bud- ding of some of the ohgochaete worms, particularly as regards the proliferation of subsegments in the anterior region of the first formed divisions; but further than this the comparison can scarcely be carried. 303] PSEUDOPHYLLIDEA FROM FISHES— COOPER 15 DIPHYLLOBOTHRIIDAE Ltihe 1910, char, emend. Polyzootic Pseudophyllidea with unarmed or (seldom) armed scolex. Sur- ficial bothria variously developed; they may be modified to form sucking tubes, each with an anterior and a posterior opening, thru the growth together of their free edges, or an unpaired terminal organ of attachment caa serve as a functional substitute for the rudimentary bothria or result from the more or less complete fusion of both bothria. The whole scolex may be replaced in sexually mature specimens by a pseudoscolex ; or it may be (Haplobothriinae) provided with four protrusible proboscides. Neck present or absent. Exter- nal segmentation mostly present, seldom absent. Genital organs numerous, mostly single in each proglottis, seldom double. Cirrus unarmed (excepting in Haplobothrium), with cleft cuticula. Opening of cirrus and vagina surficial or marginal ; in the first case always on the same surface as the uterus opening and ahead of this as well as always in the median line of the genital complex, also in the median line of the proglottis in the case of single genitalia. Both surfaces of the chain of proglottides, apart from the genital openings, similarly shaped. Receptaculum seminis formed by a local enlargement of the vagina near its inner end, which as a rule is sharply separated from the spermiduct (terminal portion of the vagina). Uterus, a long, more or less winding canal, usually in the form of a rosette, formed by almost transversely directed coils crossing the median line. It may be locally more or less enlarged, but seldom forms an undivided uterus-sac distinct from the uterine duct, as in the Ptycho- bothriidae. Eggs thick shelled, with opercula, excepting in the Marsipome- trinae; their formation is carried on continuously in fully-developed proglot- tides; embryonal development takes place usually after liberation, seldom in the uterus, in which case, however, all stages are found side by side. Parasites of vertebrates. Llihe's (1910:16) diagnosis is here emended to include the new subfamilies Haplobothriinae and Marsipometrinae. In the former not only is the scolex radically different from that of any other member of the family, but the cirrus is armed with minute spines and there is a distinct uterus-sac, separate from the uterine duct as in the Ptychobothriidae; while in the latter there is likewise a uterus-sac and the eggs are not provided with opercula. The cirrus of Haplobothrium, however, would seem to exclude the genus from the family Ptychobothriidae as well as from the Diphyllobothriidae, since it is not "un- armed, with cleft cuticula," but provided with minute yet distinct cuticular spines bearing some resemblance to those of the Acanthophallidae ( Amphi- tretidae), as pointed out elsewhere by the writer (1914:3). But H. globuli- forme is otherwise so nearly related to Diphyllobothrium latum that it does not seem wise to remove it from the family on this account, especially since these spines are so minute and since the evidence points to their being probably of little, if any, functional importance. The uterus on the other hand is quite diff- l(j ILLINOIS BIOLOGICAL MONOGRAPHS [304 erent from that of any of the members of this family in that it is distinctly divided into uterine duct and uterus-sac as in the Ptychobothriidae. It is true that in the genus Sc>'phocephalus one or two of the coils of the uterine rosette becomes much enlarged when the organ is filled with eggs, while in Bothridium, as stated by Liihe (1899:49), "Der Uterus bildet keine Rosettenform, lasst jedoch Uteringang und Uterus s. str. deutlich unterscheiden; letzterer stellt gewissermassen eine zweitheilige Uterushohle dar, indem zwei hinter einander gelegene grosse Hohlraume durch einen kurzen und diinnen Canal miteinander in Verbindung stehen." But in neither case is there a single uterus-sac, distmct and separate from the uterine duct or beginning of the uterus, but only a modified rosette formation. Roboz (1882 :282) in describing the develop- ment of the uterus of Bothridium pithonis said that: "In dieser Weise ist er natiirlich nur in jiingeren Gliedem entwickelt, wahrend er dort, wo die Be- fruchtung schon beendet ist, in Folge der immer starkeren Ansammlung von den mit chitinoser Hiille umgebener Eiem immer grosser wird und sich schliess- lich zu ernem die ganze Mittelschicht ausfiillenden Sack ausbreitet. " It would thus seem to be comparable to that of the Ptychobothriidae in that its func- tional sac is developed by a distal enlargement of the original duct which grad- ually encroaches upon the medulla, but evidently there is no separation of the organ into two distinct parts at any stage as there is in Haplobothrium. And, as emphasized elsewhere by the writer, this separation is present at all stages in the development of the organ, which as a matter of fact proceeds in quite the same manner as that of Bothriocephalus. In Marsipometra, on the other hand, even tho the sac is formed in the same way, it is never very sharply separated from the uterine duct, altho such appears to be the case in the adult. Reference to the specific description below will elucidate this latter point. Finally as regards the fact that its eggs are not provided with opercula, Marsi- pometra stands alone. This character would place it at once in the Ptycho- bothriidae, but it is otherwise so closely related to the subfamily Triaenophor- rinae that the family is here emended to accommodate it. Thus it is seen that on account of these two isolated genera the two families Diphyllobothriidae and Ptychobothriidae are much more closely related than was formerly thought to be the case. LIGULINAE Liihe 1899 Scolex unarmed, very short, abnost triangular, with anterior end, more or less drawn out into a point according to the state of contraction, passing directly into the chain of proglottides or the similarly shaped unjomted body; surficial bothria small, weakly developed. Neck absent. Formation of proglottides complete, confined to the anterior end or (in young animals) absent. Posterior end roimded. Nervous system distinguished by a large number of plexus- forming longitudinal nerves near both chief strands. Genital organs in sexually mature individuals completely developed close behind the scolex. Genital openings surficial, ventral, lying behind or near one another and near the median line. Testes in a simple dorsal layer in the lateral fields of the medul- 3051 PSEU DOPEY LLIDEA FROM FISHES— COOPER 17 lary parenchyma, for the most part lateral to the nerve strands. Ovary and shell-gland median, the former ventral, the latter dorsal. Vitelline foUicles in the form of a mantle in the cortical parenchyma. Vas deferens enlarged to a muscular bulb before entering the cirrus-sac. Receptaculum seminis large, sharply separated from the short and narrow spermiduct. Sexually mature in the intestines of water birds; present as larvae in the body-cavities of teleosts where they grow quite large and develop the rudiments of the reproductive organs; occasionally also observed free in the water which they reach by the rupture of the greatly distended body-wall of the intermediate host. Type genus: Ligula Bloch In the above diagnosis of the subfamily by Liihe (1910:17) the statement that the testes are "in einfacher dorsaler Schicht den Seitenfeldem des Mark- parenchyms grossentheils lateralwarts von den Markstrangen " is somewhat confusing, for it is strictly correct only when the whole number of testes is taken into consideration. In transections of both Ligula and Schistocephalus the nerve strand was actually found to be more than half way from the median line to the margin of the medulla, but the testes were much more closely crowded in the lateral portion of the field, hence making their total number there more than in the median field. But the differences between the two fields on each side in this regard were seen in confirmatory frontal sections to be much greater in Ligula than in Schistocephalus. LIGULA Bloch 1782 Taenia (part.) Auctorum Fasciola (part.) Linnaeus 1758 Fasciola (part.) Linnaeus 1767 Ligula Bloch 1782 Fasciola (part.) Goeze 1782 Bothriocephalus (part.) Nitzsch 1824 Ligula Creplin 1839 Dibothrium (part.) Donnadieu 1877 Bothria as well as external segmentation completely absent from the larvae, both develop simultaneously with the maturation of the sex-organs in the definitive host, where the external segmentation which does not correspond with the internal is confined to the anterior end. Longitudinal and transverse muscles irregularly interwoven in the anterior end, posteriorly separated into an inner transverse and an outer longitudinal layer. Type (and only) species: Ligula intestinalis (L.). 18 ILLINOIS BIOLOGICAL MONOGRAPHS (306 LIGULA INTESTINALIS (Linnaeus [Figs. 1, 2, 78, 98] 1758) LARVAL STAGE : 1713 Taenia 1740 Taenia capitata 1758 Fasciola intcstinalis 1767 Fasciola intestinalis 1781 Taenia cingulum 1782 Ligida piscium 1782 Fasciola abdomindis 1790 Ligida abdominalis 1790 Ligida a. alburni 1790 Ligida a. hramae 1790 Ligida a. carassii 1790 Ligida a. cobiiidis 1790 Ligida a. cyprinorum 1790 Ligula a. gobionis 1790 Ligida a. leiiscisci 1790 Ligida a. trincae 1790 Ligula a. vimbae 1790 Ligida pelromyzontis 1793 Ligula sahclini 1802 Ligida simplicissima 1803 Ligida alburni 1803 Ligida braniae 1803 Ligida carassii 1803 Ligida cobiiidis 1803 Liguli colymbi 1803 Ligida gobionis 1803 Ligida leucisci 1803 Ligida trincae 1803 Ligula vimbae 1810 Ligida acuminata 1810 Ligida cingulum 1810 Ligula constringens 1810 Ligida contortrix 1819 Ligida simplicissima 1819 Ligula crispa 1819 Ligida edulis 1839 Ligida simplicissima 1839 Ligula monogramma 1839 Ligula digramma 1853 Ligula simplicissima 1855 Ligida monogramma 1861 Ligula monogramma 1891 Ligida catostomi 1896 Ligida monogramma 1898 Dibothrium ligula 1899 Ligula abdominalis ADULT stage: 1782 Ligula avium 1782 Fasciola intestinalis Geoffrey 1713 :50 Frisch 1740 : 121 Linnaeus 1758 : 649 Linnaeus 1767 : 1078 Pallas 1781 -.95 Bloch 1782 :2 Goeze 1782 : 187 Gmelin 1790 : 3043 Gmelin 1790 : 3043 Gmelin 1790 :3043 Gmeliu 1790 . 3043 Gmelin 1790 .3043 Gmelin 1790 .3043 Gmelin 1790 :3043 Gmelin 1790 : 3043 Gmelin 1790 : 3043 Gmelin 1790 : 3043 Schrank 1790 : 119 Schrank 1793 : 143 Rudolphi 1802 : 99 Zeder 1803 -.266 Zeder 1803 :263 Zeder 1803 : 262-3 Zeder 1803 :266 Zeder 1803 :266 Zeder 1803 265 Zeder 1803 265 Zeder 1803 .265 Zeder 1803 .295 Rudolphi 1810 24 Rudolphi 1810 20-22, 31 Rudolphi 1810 22-24 Rudolphi 1810 18-19 Rudolphi 1819 134 Rudolphi 1819 134-135 Briganti 1819 209 Creplin 1839 295 Creplin 1839 296 Creplin 1839 296 Baird 1853 95 Leidy 1855 444 \'^an Beneden 1861 139 Linton 1891 66 Zschokke 1896 773, 774, 775 Linton 1898 438 Liihe 1899 52 Bloch 1782 4 Goeze 1782 183 307] PSEUBOPHYLLIDL :a from fishes- -COOPER ADULT STACK 1790 Ligula intestinalis Gmelin 1790 :3042 1802 Ligula simplicissima Rudolphi 1802 :99 1803 Ligula colymhi Zeder 1803 :266 1810 Ligula uniserialis Rudolphi 1810 : 12 1810 Ligula allernans Rudolphi 1810 : 13 1810 Ligula interrupta Rudolphi 1810 :15 1810 Ligula sparsa Rudolphi 1810 :16 1819 Ligula uniserialis Rudolphi 1819 -.132 1819 Ligula allernans Rudolphi 1819 : 133 1819 Ligula inkrrupla Rudolphi 1819 : 133 1819 Ligula sparsa Rudolphi 1819 : 133 1824 Bothriocephalus scmiligula Nitzsch 1824 :98 1839 Ligula uniserialis Creplin 1839 :296 1839 Ligula interrupta Creplin 1839 :296 1844 Ligula sparsa Bcllingham 1l Notropis corniitus Go-Home Bay A. R. Cooper Notropis cayuga Douglas Lake, Michigan H. R. Hill 11 Notropis ktidsonius Douglas Lake, Michigan G. R. LaRue 1> Micropterus dolomieu Go-Home Bay A. R. Cooper l» AmUoplites rupeslris Go-Home Bay A. R. Cooper » Ambloplites rupestris Douglas Lake, Michigan G. R. LaRue » Caslerosteus bispinosus Chamcook Lake, atkinsii New Brunswick A. R. Cooper l> Amhy stoma sp. Sand Hills, Nebraska G. R. LaRue 91 Amby stoma tigrinum Cherry Co., Nebraska G. R. LaRue >I Free on shore Douglas Lake, Michigan H. R. Hill G. R. LaRue A. R. Cooper Adult stage: Falco albicilla Greiphswald Creplin Creplin 1839 : 296 Ciconia alba Hildebrandt Diesing 1850 : 580 Ardea nycticorax M. C. V. Mehlis Parona Diesing Diesing Parona 1850 : 580 Colymbus arciiciis 1850 : 581 Podiceps aiiritus Varese 1902 : 7 Anas boschas fera Mus. Vienna Rudolphi 1819 : 134 Larus argentatus Kainsk, Enissej Middeadorfif Linstow 1903 : 20 Sterna hirundo Mus. Vienna Schneider Rudolphi Schneider 1819 : 133 Mergiis serrator Gulf of Finland 1902a : 13 Nycticorax nycticorax Liihe 1910 : 18 Graculus carbo M. Siebold, Coll. Brit. Museum Baird 1853 96 Fuligida clangula Jemtland Olsson Olsson 1893 15 Xcma minutum Trieste Stossich Stossich 1898 118 Urinator arcticus Liihe Liihe Liihe Liihe Liihe Liihe 1900 1900 1900 1910 1910 1910 18 Rissa tridactyla 18 Stercorarius parasitica 18 Hydrockelidon nigra 18 Herodias alba 18 Haliaetus albicilla 18 311] PSEUDOPHYLLIDEA FROM FISHES— COOPER 23 HOST LOCALITY COLLECTOR AUTHORITY Aquila chrysaetus CoTvv.s comix Luhe 1910 : 18 Luhe 1910 : 18 Podilyrnbus podiceps Merganser sp. Colymbus hoelbeelli Mergiis merganser H. B. Ward H. B. Ward H. B. Ward G. R. LaRue Cooper (the present Urbana, Illinois paper) »» Douglas Lake, Michigan i> The species has also been reported in Europe and Asia from the following additional hosts: Larval stages: Abramis bjorkna, A. blicca, A. vimba, Alburnus alburnus, Ammocoetes branchialis, Aspius alburnus, Carassius car assius , C. vulgaris, Cobitis aculeata, Cyprinus blicca, C. brania, C. carassius, C. gobio, C. lacustris, C. leucis- cus, C. tinea, Gobio fliiviatilis , Leuciscus erythrophthalmiis , L. leuciscus, L. phoxinus, L. pulcheUus, L. vulgaris, Lucioperca lucioperca, Squalius turcicus. Adult stages: Ardea alba, A. ciconia, A. egretta, Ciconia ciconia, C. nigra, Colymbus auritus, C. cristatiis, C. griseigena, C. rubricollis, C. septentrionalis , C. subcristatus, Falco chrysaetos, F. fulvus, Larus canus, L. melanocephalus, L. parasiticus, L. pelecanus carbonis, L. pygmaei, L. ridibundus, L. tridactylus, Mergus albellus, M. merganser, M. niinutus, Podiceps minor, P. nigricollis, P. rubricollis, Sterna nigra, Tetanus chloropus, Urinator stellatus, Xema ridi' undum. As indicated in the above s>Tionymy, the greatest confusion has existed in connection with this species from the time of Linnaeus to that of Liihe (1899), all of the older writers recognizing at least two species, the larval and the adult, and many, several species under each of these. Rudolphi (1810), for instance, accepted four species of the former, "ovariis occultatis, " and the same number of the latter, parasitic in the intestines of birds, "ovariis distinctis. " In his Entozoorum Synopsis (1819) he reduced the number of larval species to two, but retained the same four adult forms as before. The next important move in a systematic direction was by Creplin (1839) who divided Rudolphi's L. sirnplicissima into two larval species, viz., L. monogram- ma and L. digramma, corresponding respectively to the previously known L. uniserialis and L. interrupta (or alternans), which plan was followed by Diesing (1850, 1854, and 1863) while Dujardin (1845) and Baird (1853) followed Ru- dolphi. Diesing (1850:581) erected a third species, L. reptans, to accommodate numerous forms found encysted in the muscles and connective tissues of am- phibians, reptiles, birds and mammals ; but as pointed out by Janicki (1906:519) several larval species were probably included under this heading. Those from avian hosts are not given above since they were found only among the 24 ILLINOIS BIOLOGICAL MONOGRAPHS [312 muscles and iinder the skin, where L. intestinalis has never been found in birds, so far as the available records indicate. Liihe (1910:18) did not include them in his Hst of hosts for the adult stage of the species. Next in order of importance came Donnadieu's (1877) classical experiments in which, after completely reviewing the hterature up to date, he conclusively- proved that the form found in the body cavities of various bony fishes is the larval stage of that present in the intestines of birds. As a result of his work he combined the two forms under a new name, Dibothrium ligula, confusing at the same time Schistocephalus solidus with Ligula intestinalis. The life- history of the species was later studied by Riehm (1882) by feeding methods. Moniez (1881:37, 81) was the first writer to study the histology of the species, while Kiesshng (1882) gave the first description of its general anatomy. As emphasized, however, by Linstow (1901a), Kiessling's work is not very specific, since he ahnost constantly disposed of L. intestinalis by saying that in it conditions were the same as in Schistocephalus solidus. While, apart from Donnadieu and the earlier writers, Willemoes-Suhm (1870:94) was the first to study the development of the embryo with attention to detail, Schauins- land (1885:550) enlarged upon his observations and gave a more or less com- plete description of the process up to the time of the escape of the ciliated larva. Niemiec (1888:2) described the nervous system, and Cohn (1898:134) pointed out its resemblance to Sch. solidus in this regard. Zernecke (1895) in the mean- time dealt in his well known work on the finer structure of cestodes with the parenchyma and the nervous and muscular systems in particular; since then little has been done in that connection. The question of segmentation was studied by Liihe (1898). Later the same writer (1899:52) placed the species in his first classification, stating as his belief that there is only one species of Ligula, viz., L. intestinalis (L). The latter conclusion was also arrived at by Linstow (1901a :628), altho he attributed the specific name to Goeze; while in his latest classification Liihe (1910) maintained the same view. Consequently, taking for granted in the absence of European material for comparison that the latter has been established as a fact for the European forms, the problem is to determine whether the same species occurs here in America. So far as the majority of specific characters are concerned, one must rely on the descriptions of Kiessling and Linstow (1901a) who seem to have been the only Avriters to attend to the details of the reproductive system, — and as metioned above, Kiessling's is quite inadequate in this connection. The only American reports of the species are of larval forms: L. monogramma by Leidy (1855:444) and Dibothrium ligula by Linton (1898:438), the former having also listed (1856:46) the doubtful L. reptans. Luhe (1910:18) gave the dimesionsof the species as 100 to 400 mm. (occasion- ally 1 meter) in length by from 5 to 15mm. in breadth, not distinguishing how- ever, between the larva and the adult in this regard. Linstow (1901:629) reported a larva from Blicca bjorkna 200mm. long, 9 broad and 3.5 thick, adults from Podiceps cristatus and Merganser merganser 160mm. long, 4 broad and 1.5 thick. Concerning these differences he said that: " Wenn man die Geschlechts- 313] PSEUDOPHYLLIDEA FROM FISHES— COOPER 25 form aus Vogeln oft kleiner findet als die Larve aus Fischen, so mag das seinen Gmnd datin haben, dass die letztere sich in der Grosse ihren Wirth anpasst; die grossen Larven in grossen Fischen konnen aber nicht von kleineren Vogeln verschlungen werden. " The largest larval specimen at hand was one from Catostomus commersonii which measured 425mm. in length by 15 in maximum breadth, but the largest adult from Merganser merganser was only 217 by 6mm. In the larva the anterior end is somewhat bluntly rounded (Fig. 1), the bothria being visible as very short grooves passing over the tip, while in the adult they are more elongated and distinct, the end of the strobila being somewhat pro- truded as shown in figure 2. On each surface of the larva there is a deep, median, longitudinal furrow, which however, becomes obUterated in the adult, except- ing anteriorly, by the growth of the reproductive organs, the ducts of which are confined to the median Hne of the strobila. When these are developed the strobila is characterized dorsally by a low median ridge bounded on each side by a quite shallow groove, and ventrally by a greater thickening of the median line, not separated, however, by any grooves from the lateral regions. The whole strobUa gradually tapers from a short distance behind the anterior end, where the maximum breadth is located, to the posterior end. Whereas in the larva it is quite thick, in the adult it is thin and leaf-like, the margins usually appearing wavy in alcohoHc specimens, especially posteriorly. A pseudosegmentation is present in the anterior end of the strobila, but as has been known, especially since Liihe (1898) emphasized the fact, this division of the strobila into segments does not correspond with the internal division into true proglottides. Gemmill (1909:11) counted about 50 of them in the anterior third of the worm, the writer 38 or 39 for a distance of 13mm. from the tip of one adult specimen (Fig. 2) and 36 for 10mm. in another. They vary considerably in length and are often incomplete medially. From the anterior region showang external segmentation to the posterior end both larvae and adults, but particularly the latter, are crossed by very numerous irregular grooves, which give the worm its characteristic appearance apart from the general shape as contrasted, for instance, with the closely related Schistocepha- lus solidus. The smallest larva met with was one from a small specimen of Micro pterus dolomieu, 47mm. in length. It gave the following measurements: length, 4.9mm.; maximum width, 0.54mm. ; \\ddth one-third the length from the anterior end, 0.54mm., two-thirds, 0.37mm.; length of bothrial groove about 0.07mm. The cuticula was found to have a thickness of from 5 to 15/x, compared with 16 to 18yu by Kiessling and 2.1 (!) by Linstow. It appears homogeneous in sections rather than divisible into the three layers described by the former, with some tendency, however, for the outer one-quarter to one-sixth to take the stain much less than the remainder of the tissue, which outer clearer area is often bounded by a very delicate pseudociliated layer. There is a good deal of variation not only in the thickness of the cuticula but also in its structure; and these remarks apply to the larva as well as to the adult. The subcuticula varies from 50 to llO.u in thickness, or 33 to 49ju according to Kiessling and 26 ILLINOIS BIOLOGICAL MONOGRAPHS [314 1 14m to Linstow. Calcareous bodies in the characteristically fine parenchyma, described by Moniez and Zernecke, and given dimensions of 13 by 7.8/x by Linstow, were observed in the largest living specimens from the body-cavity of Catostomus commersonii commersonii to be extremely numerous, spherical to ellipsoidal in shape and to measure from 14 to 19/i in length by 12 to 17 in breadth. The musculature has been well described histologically by Zernecke (1895) ; while KiessUng spoke rather briefly of its arrangement in the late larva. Later Liihe dealt with the system in general (1897a and 1898) and its relation to the nervous system (1896), and Linstow (1901a), gave a concise account of its arrangement. The chief nerve strands are situated in transections between the lateral and median quarters of the transverse diameter of the strobila, in the median frontal plane, that is below the neighboring testes, and with a diameter of 50 to 100/x. The details of the system have been studied by Moniez (1881), Niemiec (1888), Zernecke (1895), andCohn (1898), the latter of whom found conditions pretty much as in Schistocephalus, namely, that each chief strand has associated with it six collateral strands, arranged in three groups of two each. The excretory system was studied by Moniez and Zernecke in considerable detail. Linstow stated that two regions accommodating numerous longi- tudinal vessels are present: (1) an outer, close beneath the vitelline glands, and (2) an inner, between the inner longitudinal and transverse muscles, or as Linstow figured, between the former themselves. In the material studied an outer plexus appeared close beneath, among, or most often just outside of the vitelHne glands (cortical); a second and quite indistinct one among both sets of muscles, and a third, or innermost layer, as prominent as the outermost, almost in the median frontal plane of the medulla. The sets of genitalia, beginning about 10mm. from the anterior end and very closely crowded together in the longitudinal direction, lie from 0.05 to 0.20mm. apart, 0.13 to 0.15mm. being the data given by Linstow. The open- ings are usually almost exactly in a transverse line; but the cirrus and uterus openings alternate irregularly from side to side, that of the vagina being con- stantly in the middle. This alternation of the openings is due to the similar alternation of the internal organs and evidently was the basis upon which the earlier species L. digramma and L. alternans were established. The genital cloaca is a quite irregular transverse depression, 0.18 to 0.20mm. in width and 0.02 to 0.03mm. in length, the respective measurements by Linstow being 0.106 and 0.026mm. "The testes lie in a single row, which is only interrupted by the uterus, on the dorsal side of the medulla. ..." They are from 20 to 40 in number in transections, ellipsoidal in shape, their greatest diameters being transverse, as indicated by the maximum width, length, and depth being, respectively, 115 to 145, 45 to 55, and 80 to 85^. Linstow gave them as 150 to 180)u long by 88 to 156ju wide. The loosely coiled vas deferens is situated above the cirrus-sac 315] PSEUDOPHYLLIDEA FROM FISHES— COOPER 27 (Fig. 78) and roughly divided into two parts by the lateral coils of the uterus^ one part being immediately above the cirrus-sac and the other close to the dorsal body wall. The duct attains a diameter of 35/i when filled with sper- matozoa. Distally it expands into the very small (as compared to that of Sell, solidus) seminal vesicle, situated close to the dorsal wall of the cirrus-sac. The vesicle is from 65 to lOO^i in length by 40 to 90/i in diameter (156 by 86jLt, Linstow), oval in shape, the narrower end towards the cirrus pouch, and pro- vided with only a comparatively feeble musculature. The wall of the struc- ture is richly supphed both internally and externally with nuclei which are respectively those of the lining epithelium and the myoblasts, as in Schisto- cephalus. The epithelium is strongly ciliated. The cirrus-sac (Fig. 78) is an ovoid body, somewhat flattened dorso-ventrally and obliquely by the uterus, and alternating irregularly from right to left, always occupying the opposite side of the median line from the ovarian isthmus and the neighboring female ducts. Its wall is quite thin, while apart from the cirrus proper which occupies the distal two-thirds, the contents consist of loose parenchyma and only a few retractor muscles. The measurements of the organ in sections are: dorsoven- tral diameter, 185 to 215; width, 130 to 160; and length, 130 to 145^^; which are quite at variance with Linstow's diameter of 53/x of what he described as a spherical organ. Within the cirrus-sac the vas deferens is not sharply separated into ejaculatory duct and cirrus proper, altho the latter is quite distinct, closely coiled, and as much as 25yu in diameter. The vagina opens into the common genital cloaca, if one may use that name for the depression mentioned above, in the median line and usually equidistant from the openings of the cirrus and uterus. It passes dorsaliy thru the cortex and the musculature with almost a straight course. Then within the medulla it turns sharply posterolaterally, in which portion of its course it has a diameter of from 15 to 30/^ (5/i, Linstow). Its thin lining of cuticula, directly continuous with that of the genital depression, gradually passes into a nucleated epithelium, in which no distinct cell boundaries appear, just within the cortex. Dorsal to the ovarian isthmus it enlarges into an elongated receptaculum seminis which has a diameter of from 75 to 90/i. Linstow described a spindle-shaped terminal receptacle, 13ju in diameter, and an oocapt as follows: "dorsal von der Ver- einigungsstelle der beiden Keimstocksfliigel liegt der ovale, 0.088mm. lange und 0.066mm. breite Schluckapparat " ; each of which, however, in comparison with that described here by the writer and for Sch. solidus below, seems to have been confused with the other. At least the oocapt of none of the bothriocephalids described here is relatively so large as indicated by Linstow in his measurements and in his figure, nor is the receptaculum as spindle-shaped as shown in the latter. In this connection Kiessling described a swelling of the vagina, 46/x in diameter, which contained spermatozoa. The spermiduct is so short and of such a small cahbre that it is quite difficult to locate it in sections. After pur- suing a horizontal course it unites with the oviduct a short distance from the oocapt (Fig. 98) much as in Sch. solidus. It is from 20 to 25n in length and 6 to 12/i in diameter. The ovary is asymmetrical, as stated by Kiessling but 23 ILLINOIS BIOLOGICAL MONOGRAPHS [316 denied by Linstow, since it consists of a much depressed lateral wing, situated close to the ventral musculature (Fig. 78) and a more median enlarged portion which functions as the isthmus in that the oviduct arises from it. This isth- mus-like region is not in the median line but about 0.25mm. from it, the whole organ altematmg irregularly from right to left, constantly opposing the cirrus- sac on the other side. It varies from 0.55 to 0.64 mm. in width and has a length laterally of 0.12mm. Its imusual situation is evidently due to the closely crowded condition of the reproductive organs and the pressure exerted by the large uterus in the median Hne. Whereas the wing has a maximum dorsoventral diameter of about 60/i, the isthmus is about 95m in depth and roughly ellipsoidal in shape, protruding in sections from the dorsal region of the junction of the wing (Fig. 78). Ova from the isthmus were found to be oval to spherical in shape and from 12 to 15m in diameter (13 to 16m, Linstow). The oocapt is directed horizontally away from the side of the isthmus and from the median line. Its diameter is from 18 to 20m,— with which compare the dimen- sions of 88 by 66m given by Linstow. The oviduct has a diameter of from 15 to 20m. Taking a general dorsal course, after being joined by the spermiduct, it soon receives the common vitelline duct (Fig. 98) which has only a limited enlargement from a previous diameter of 10 to 20 to 30m in the form of a vitelline reservoir, located close to the oviduct with a length of 40m. The vitelline follicles are situated in a layer close beneath the subcuticula and un- broken, excepting in the median ventral line. The individual follicles, very irregular in shape, are 50 to 70m in depth and 15 to 30m in width, Linstow's measurements being 65 by 47m and Kiessling's 6m in the larva. Concerning the shell-gland Linstow said: "Die Schalendruse ist ein 0.088-0. 105mm. grosses Organ, das dorsal von der Mitte des einen Keimstockflugels an der entsprechen- den Aussenwand der Uterus liegt; die Zellen, deren kleiner Kern sich intensiv farbt, sind 0.0039mm. gross. " In the sections studied by the writer it was found to be a quite irregular structure, composed of greatly elongated club- shaped cells with necks of different lengths which unite with the oviduct in a region only about 30m in length and situated just beyond the point of reception of the common vitelline duct (Fig. 98). These cells are so loosely arranged and their proximal attenuated portions of such a fiUform nature that they are very easily overlooked, especially since they are scattered thruout the whole of the dorsoventral diameter of the medulla of the region and are interwoven among the oviduct, the receptaculum, the vitelHne duct and the beginning of the uterus. They form by no means such a compact organ as Linstow's descrip- tion and figure would indicate. The distal ends of the cells are about 15 by 10m in size, while their nuclei are about 4m in diameter. Kiessling described the shell-gland as similar to that of Sch. solidus, and as follows: "Die Schalen- driise besteht aus Drlisenzellen, welche an feinen Stielchen befindUche Blaschen an der Oberflache einer Halbkugel angeordnet sind imd ihre Stielchen als Radien nach dem Mittelpunkte der Kugel senden. " His figures of such a compact region are likewise quite different from conditions described here. The uterus forms a mass of coils, 0.4 to 0.6mm. in diameter in the median 317] PSEUDOPHYLLIDEA FROM FISHES— COOPER 29 line, from which a straight portion passes ventrally thru the musculature and cortex to the opening which is about 20/i in diameter (35^, Linstow). The diameter of the duct is 60ju in the median frontal plane but only half that amount as it passes thru the longitudinal muscles. The measurements of the eggs are according to Kiessling and Linstow, respectively, 49 by 34ju and 65 by 42ju : they were found by the writer to be 50 to 54 by 30 to 33n in sections. Our knowledge of the life-history of the species is confined chiefly to the works of Duchamp (1876), Donnadieu (1877) and Riehm (1882) who firmly established the well-known fact that the larva present in the abdominal cavities of various species of teleosts develops rapidly in the intestines of fish-eating birds. The production of eggs begins after about 36 hours, while the adults live for from three to four days only in the definitive hosts. Apart, however, from these and other closely related details which were brought out by Donn- adieu by means of well conducted and controlled experiments, nothing is known, so far as the writer is aware, of the development of the oncosphere in the intermediate host up to the time when it becomes distinguishable as a small larva. The measurements of the smallest larva found in connection with this study have been given above; another slightly larger specimen was 6.1mm. in length by 1.34mm. maximum breadth. Altho the above description shows many discrepancies between the species as here dealt with and the European form, the writer does not feel justified in separating the two specifically, especially in the absence of European material for comparison. The thickness of the cuticula, and subcuticula, the dimen- sions of the testes, seminal vesicle and cirrus-sac and the diameter of the vagina show the greatest differences, apart from the probable confusion by Linstow of the oocapt and receptaculum seminis, while the measurements of the eggs as here given are somewhat intermediate between those by Kiessling and Linstow. But the fact that the data given by the latter are apparently the only adequate ones for the adult and that there are not a few discrepancies between KiessUng's and Linstow's accounts restrains one from looking upon this, the American form, as new. In dealing with this question of identity it must also be remembered that not only does the species vary so much that, as pointed out above, a great deal of confusion exists in the earlier literature, but that the number of host species of the larva as well as of the adult is very large as compared to other species of bothriocephaUds, hence introducing greater factors for variation. And above all the geographical distribution of the wading and diving birds harboring the mature worms is such that here in America there are many of the same species as well as the same genera that occur in Europe. As the above record of hosts indicates, the species certainly ranges widely over Europe and Northern Asia, so that it would be quite sur- prising if it did not occur here in North America, with the probable region of transition in Iceland and Greenland on the east and northeastern Siberia and Alaska on the west. However apart from Leidy's and Linton's records it has apparently not been reported up to the present. 30 ILLINOIS BIOLOGICAL MONOGRAPHS [,^1 •', The material studied by the writer consisted of the following lot of larvae: Nos. 4706 and 4708 of the collection of the United States National Museum; Ch 18a, 16.411, 16.413, 16.414, 16.419, 17.31 and 17.32 of the collection of the University of Illinois, under the care of Professor H. B. Ward; Nos. 49b, 70 to 79, 1 10 to 1 19, 361 to 370, 427 and 431c of the collection of Dr. G. R. LaRue ; Nos. II, III, IV, and V from the collection of Mr. H. R. Hill; and Nos. 47, 54, 150, 158, 159, 160, 189, 190, 312, 313, 314, 317, 319, and 330 of the writer's collection; and the adults contained in Nos. La 156, 17.184, and 17.185 of the collection of the University of Illinois, respectively from the intestines of Merganser sp., Podilymbus podiceps and Colymbiis holboellii, and No. 387g of the collection of Dr. LaRue from the intestine of Mergus merganser. SCHISTOCEPHALUS Creplin 1829 Taenia (part.) Auctorura Hirudo (part.) Linnaeus 1745 Fasciola (part.) Liiinaeus 1767 Rhytis (part.) Zeder 1800 Halysis (part.) Zeder 1800 Bothriocephalus (part.) Rudolphi 1808 Schistocephalus (part.) Creplin 1829 Bothria and external segmentation developed in the larva. The tip of the scolex retractile. Segmentation complete and corresponding to the internal structure of the animal. Longitudinal and transverse muscles arranged in several alternating layers (three transverse layers enclosing two longitudinal layers). Type (and only) species: Schistocepliahis solidus (O. F. Miiller). SCHISTOCEPHALUS SOLIDUS (0. F. Miiller 1776) [] Mgs. 3, 79, 80] LARVAL stage: 1734 Taenia Frisch 1734 :395 1745 Hirudo depressa alba Linnaeus 1745 :250 1758 Fasciola hepatica Linnaeus 1758 :648 1761 Taenia laia Pallas 1761 :410 1767 Fasciola hepatica Linnaeus 1767 : 1077 1776 Taenia solida Muller 1776 -.219 1780 Taenia gaslerostei Miiller 1780 :22 1780 Taenia gaslerostei Fabricius 1780 :320 1781 Taenia aculissima Pallas 1781 : 76, 78 1786 Taenia gaslerostei Batsch 1786 :224 1788 Taenia solida Schrank 1788 :49 1790 Taenia solida Gmelin 1790 : :3079 1790 Taenia gasterostei Abildgaard 1790 : : 49-58 1800 Rhytis solida Zeder 1800 :297 1810 Bothriocephalus solidus Rudolphi 1810 : :57 1819 Bothriocephalus solidus Rudolphi 1819 : 139, 477 1819 Bothriocephalus solidus Leuckart 1819 : 46 319] PSEUDOPHYLLIDEA FROM FISHES— COOPER 31 1824 Boihriocephalus solidus 1829 Boihriocephalus solidus ? 1863 Schistocephalus rhynchich- thydis 1896 Schistocephalus dimorphus 1896 Schistorhynchus dimorphus 1898 Schistocephalus dimorphus 1898 Schistocephalus solidus 1898 Schistocephalus solidus 1899 Schistocephalus solidus 1909 Schistocephalus solidus ADULT stage: 1782 Taenia lanceolata nodosa 1786 Taenia lanceolata var. [i 1788 Taenia nodularis 1790 Taenia lanceolata nodosa 1790 Taenia gasterostei 1793 Taenia lanceolata nodosa 1800 Halysis lanceolata nodosa 1810 Boihriocephalus nodosus 1819 Boihriocephalus nodosus 1819 Boihriocephalus nodosus 1824 Boihriocephalus nodosus 1829 Schistocephalus dimorphus 1839 Schistocephalus dimorphus 1845 Schistocephalus dimorphus 1850 Schistocephalus dimorphus 1853 Schistocephalus dimorphus 1854 Schistocephalus dimorphus 1858 Schistocephalus solidus 1859 Schistocephalus solidus 1863 Schistocephalus dimorphus 1869 Schistocephalus dimorphus 1877 Dibothrium ligida 1881 Schistocephalus dimorphus 1882 Schistocephalus dimorphus 1889 Schistocephalus solidus 1890 Schistocephalus dimorphus 1893 Schistocephalus dimorphus 1896 Schistocephalus dimorphus 1896 Boihriocephalus zschokkei 1898 Schistocephalus zschokkei 1898 Schistocephalus solidus 1899 Schistocephalus nodosus 1900 Schistocephalus dimorphus 1910 Schistocephalus gasterostei 1911 Schistocephalus dimorphus Nitzsch 1824 : 97 Baer 1829: ;388 Diesing 1863 : 233 Zschokke 1896 : 773 Zschokke 1896 : ;776 Linton 1898 : :427 Cohn 1898 : :126 Miihling 1898 : 33 Liihe 1899 : :52 Scott 1909 :80 Bloch 1782 i !lO Batsch 1786 ; :167 Schrank 1788 : 39 Gmelin 1790 ; 3075 Abildgaard 1790 ; ; 49-58 Rudolpht 1793 : :41 Zeder 1800 ; :340 Rudolphi 1810 :54 Rudolphi 1819 :140 Leuckart 1819 ; :58 Nitzsch 1824 :97 Creplin 1829 :95 Creplin 1839 :296 Dujardin 1845 :622 Diesing 1850 :584 Baird 1853 :92 Diesing 1854 : 19 R. Leuckart 1858 :129 Steenstrup 1859 :475 Diesing 1863 :232 Willemoes-Suhm 1869 :469 Donnadieu 1877 :495 Monniez 1881 :175 Kiessling 1882 Lonnberg 1889 :40 Lonnberg 1890 : 18 Olsson 1893 :15 Ariola 1896 :280 Fuhrmann 1896 Fuhrmann 1898 :144 Miihling 1898 ■.Z2, Liihe 1899 :52 Ariola 1900 :426 Liihe 1910 : 19 Solowiow 1911 : 123 Specific diagnosis : With the characters of the genus. Medium sized worms, length 30 to 300mm., breadth 3 to 9mm. First segment or " scolex " 0.4 to 0.8mm. in length and 1 to 1.3mm. in width. Strobila ovate-lanceolate and depressed, maximum breadth anterior to the middle ; hindermost segments narrower and 32 ILLINOIS BIOLOGICAL MONOGRAPHS [320 flatter, 0.25 to l.Omm. in length by 1 to 3mm. in width, forming an appendage up to 10mm. in length; medium segments 0.1 to 0.5mm. long, posterior borders prominent. Shallow median groove on the ventral surface. Cuticula 15 to 20^t in thickness; subcuticula 40 to GS/x. Layer of internal longitudinal muscles 15 to 50^t in thickness. Nerve strands 30 to 75;u in diame- ter. 25 to 30 excretory vessels in transections. Genital cloaca median, shallow, with a diameter of 90/i; no hermaphroditic duct. Opening of vagina close behind that of cirrus and to one side but not so far as that of the uterus, both alternating irregularly from side to side. Testes extend from the median genital ducts laterally to the edges of the medulla, unbroken from proglottis to proglottis, closely crowded, 240 to 480 in number for each proglottis, 85 to 100/x in depth, 40 to 65 in width and 55 to 85 in length. Vas deferens median, dorsal, closely applied to the seminal vesi- cle, the whole mass 0.30mm. in diameter, the duct itself 35 to 60/1. Seminal vesicle 175 by 150/i, walls 25ju in thickness. Cirrus-sac oval in shape, immediate- ly below the seminal vesicle, 0.185 to 0.203 by 0.203 to 0.212 by 0.166 to 0.185 mm. in dimensions. No inner seminal vesicle. Cirrus proper not sharply separated from the ductus ejaculatorius; whole surrounded by numerous retractor muscles. Vagina 45 to 60/i in diameter just within the medulla. Receptaculum seminis large, 92 to 105)u in diameter. Spermiduct unites with the oviduct close to the ventral wall of the medulla. Ovary with large wings consisting of closely arranged tubules, whole organ 0.6mm. in width, wings 0.10 in length. Ova ISfjL in diameter, their nuclei 5/x. Oocapt 35 to 40/x in diameter, oviduct 25 to 30/x. Vitelline gland unbroken at margins of the proglottis, from proglot- tis to proglottis, and medially, excepting for small areas above and below the proximal reproductive ducts; individual follicles 55 to 90 by 18 to 26/i. Ootype 16 to 20^ in diameter. Shell-gland shghtly to one side of median line. Uterus 85 to 135/i in diameter at its middle; the terminal portion directed dorsoventrally and hned with cuticula distally ; opening at the bottom of a slight invagination of the ventral body wall, formed by the rupture of a pre- existing cuticular membrane. Eggs, 38 to 65 by 22 to 38/z. Habitat: As larvae in the body-cavities and occasionally in the stomach and intestine of bony fishes ; adults in the intestines of wading and diving birds. 321] PSEUDOPHYLLIDEA FROM FISHES— COOPER 33 HOST LOCALITY COLLECTOR AUTHORITY Larval stage: Gasterosteus aculeatus Greenland Fabricius Fabricius 1780 : 320 Coitus poecihpus L. Storsjon, Sweden Olsson Olsson 1893 : 15 Cottus bairdii Swan R., Mont. Everman Linton 1898 : 427 Saltno solar Basel Zschokke Zschokke 1896 : 776 Phoca vUulina Gryphswald Rudolphi Rudolphi 1819 :140 Rhynchichihys gronovii Hayti Weinland Diesing 1850 : 585 Gasterosteus bispinosus Chamcook L., A. R. Cooper Cooper (th e present atkinsii New Brunsmck paper) Uranidea formosa Port Credit, Ontario A. R. Cooper T» jj Gasteroseus cataphradus R. P. Lake, St. Paul Id., Pribilof C. E. Crompton )I >> Ids., Alaska Adult stage : Corvus comix East Prussia Braun Muehling 1898 : 34 Recurvirostra avocetta Schilling Diesing 1850 : 584 Ardea stellar is Genf Fuhrmann Fuhrmann 1896 : 546 Ciconia alba East Prussia Braun Muehling 1898 : 34 Sterna hirundo GrjTJhswald Rudolphi Rudolphi 1819 : 140 Colymbiis septetitrionalis Firenze, Italy Condorelli Parona 1899 : 8 Podiceps nigricollis Bracciano, Italy Parona Parona 1899 :8 Larus ridibundus Rossitten Muehling Muehling 1898 : 34 Anas glacialis Mergus serralor Creplin Olsson Diesing 1850 : 585 L. Storsjon, Olsson 1893 : 15 Jemtland, Sweden Uria troile Abildgaard Diesing 1850 : 585 Ale a tor da Leipzig C. W. Stiles Stiles and Hassall 1894 : 322 Tolanus calidrus Jaederen, Norway Loennherg Loennberg 1890 : 18 Harelda giacialis Pillau Muehling Muehling 1898 : 34 Fuligtda marila Pillau Muehling Muehling 1898 : 34 Haematopus oslrealegus Pillau Muehling Muehling 1898 : 34 Fulica atra Portoferrajo, Id. Elba Damiani Parona 1899 : 7 Puffinus kuhli Portoferrajo, Id. Elba Damiani Parona 1899 :7 Urinator arcticus Liihe Liihe 1910 : 19 Stercorarius parasiticus Nyroca marila 1910 : 19 Luhe 1910 : 19 Lophodytes cucullatus Lincoln, Nebr. H. B. Ward Cooper (the present paper) The species has also been reported in Europe from the following additional hosts: Larval stage: Cottus scorpio, Fulica atra, Gasterosteus pungitius, Totanus calidrus, and Rana escuJenta ; 34 ILLINOIS BIOLOGICAL MONOGRAPHS [322 Adult stage: Alca pica, Ardea cinerea, Ciconia ciconia, C. nigra, Colymbus arcticus, C. crislatus, C. glacialis, C. griseigena, C. immer, C. troile, Corvus corax, Larus argentatus, L. capistranus, L. marinus, Mergus albellus, Mergus merganser, Podiceps cr (status, P. rubricollis, Sterna arctica, S. macroura, S. minuta, S. nigra and Uria grylle. As indicated in the above synonymy this species was known for ahnost a century, at first as the larval form only and then as both larval and adult forms, before it was discovered that the two species recognized from the time of Bloch (1782) were one and the same. Abildgaard (1790), who called the worm T. gasterostei, seems to have been the first to consider the larval form found chiefly in sticklebacks to be the same as that found in fish- eating birds, since on feeding sticklebacks infected with the larvae to geese he obtained the adult form from the intestines of the latter. Yet Rudolphi (1810) did not agree with his conclusions but still considered that there were two distinct species, namely, Bothriocephalus nodosus (adult) and B. solidus (larva). And this continued until Creplin (1829) united both in one species imder a new genus, Schistocephalus dimorphus. Diesing (1863:233) made a new species out of the Schistocephalus found by Weinland (1859) in the island of Hayti in Rhynchichthys gronovii, but later writers have considered that in all probability it was only the well known larval form of this species. Wille- moes-Suhm (1869) was evidently the first to study the development of the fertilized ovum, which was later gone into more thoroughly by Schauinsland (1885:555). Donnadieu (1877), to whom all go back in their considerations of the larval development of Ligula, unfortunately fell into the error of con- sidering Schistocephalus and Ligula to be not only the same specifically but generically. The anatomy was first studied by Moniez (1881:175), more thoroughly by Kiessling (1882), and still later by Furhmann (1896) (under B. zschokkei sp. nov.) and Solowiow (1911). Linton (1897:427) is the only one, apart from Weinland's record which is only a brief foot note, who has reported the species from America. As regards the correct name of the species, it should be noted that, altho Liihe (1899:52) called the "typical and only species" of the genus Sch. nodosus (Rud.) and the larval stage Sch. solidus (0. F. Mliller), he reverted in 1910 to "Schist, gasterostei (Fabr.) ( = Sch. dimorphus Crept.)" without, however, discussing the change. But according to the Rules of Nomenclature, Art. 27 (b), the earliest name of the larval stage must hold, so that, since Liihe himself considered this to be Sch. solidus (O. F. Miiller), the writer makes use of the latter in the present paper. According to Luhe (1910:19) Sch. solidus ranges in length from 30 to 300mm. while the maximum breadth varies from about 3 to 9mm. and is located ahead of the middle of the strobila. As shown in the table below the largest and only sexually mature specimen of the six studied by the writer was only 29mm. in length by 6mm. in breadth. The scolex (Fig. 3) is, as indicated in the above diagnosis of the subfamily, not separated from the first segment into which 't runs insensibly, the whole " head " being thus triangular in shape. The bothria 323] PSEUDOPHYLLIDEA FROM FISHES— COOPER 35 are merely short median grooves which unite at the very tip not only with each other but with a frontal median groove which passes laterally into slight emar- ginations of the edges of the segments. While these emarginations were seen to be present in the anterior segment, gradually disappearing towards the mid- dle of the worm, no such "flat leaflike flaps (bothria) on the lateral margins separated from each other on flat surface by a broad, shallow sulcus," as de- scribed by Linton (1898:428) and shown in his Fig. 4, PL XXVIII, for the first segment were met with; but the posterior border was quite entire, altho as seen in figure 3, not very prominent in the vicinity of the median line in adults as well as in larvae. The bothria of the mature specimen (H. 7 of the table below) were not present, but the region where they would otherwise be was quite smooth, only a shallow, median, frontal groove appearing. The whole strobila is ovate-lanceolate, considerably depressed and provided in the adult with a very shallow median groove on the dorsal surface (Fig. 80) which seems to be due to the slight protrusion of the median reproductive organs, chiefly the cirrus-sacs and seminal vesicles, towards the ventral surface (Fig. 79) and the consequent dragging downward of the dorsal median tissues. Concerning this matter Linton said "5. dimorphus is described as having in the larval state a longitudinal median furrow on each face. These specimens do not exhibit this character; neither do they have anything that can be properly called a costa dividing the two bothria. " While in the specimens studied the dorsal groove was present not only in the adult but (not so well marked) in the larva, a similar ventral groove was also noticed in sections of the anterior end of one of the latter. Both grooves, however, are in either case so shallow as»to be easily overlooked in alcoholic specimens; they seem to be of only second- ary importance since they are apparently quite variable in their nature. While the segments in the anterior region of the strobila are very broad and com- paratively thick, short, and from 0.1 to 0.5mm. in length, posteriorly the stro- bila is considerably smaller and flatter, especially in mature individuals. In larvae the segments are much more irregular in outline and as much as 1mm. long (0.75 in the only ripe specimen studied). The segmented condition of the strobila, in contrast with that of Ligula, is rendered more apparent by the prominent posterior borders of the anterior and middle proglottides which at the margins produce the characteristic saw-tooth effect. The following table gives the measurements of two specimens with those by Linton for comparison: 36 ILLINOIS BIOLOGICAL MONOGRAPHS [324 72 H 7 4727 u. s. N. M. NUMBER Length 17mm. 29mm. 32mm. 6 Maximum breadth 5.5 6 Length of "cauda" 1.64 10 ? Breadth of same 1.1 2-3 2.5 Length of med. sags. 0.16 0.27-0.46 0.25 Length of post. segs. 0.25-0.40 0.40-0.75 ? Length of first seg. 0.46 0.46 0.80 Breadth anteriorly 0.48 0.46 0.80 Breadth posteriorly 1.11 1.11 1.30 Length of bothrium 0.07 Absent ? Condition Larval Adult Larval Since the essential features of the internal anatomy of this species have been worked out by the European workers, only the striking similarities and differences to and from the data given in particular by Kiessling, Fuhr- mann and Solowiow will here be dealt with in support of the writer's contention, in the absence of European material for comparison, that here in America we have the same species as that found in Europe. It will be considered that, as brought out by Liihe in three controversial papers (1897, 1897b, 1899a :7 15) and by Cohn (1898:126, footnote), S. zschokkei Fuhrmann 1898 is synonymous with S. solidus. As a matter of fact many of the data given below will be seen to compare more favorably with those pubUshed by Fuhrmann than with those by either Kiessling or Solowiow. According to Kiessling the cuticula is from 15 to 18/i m thickness and divisible into two layers, of which the inner and lighter is from 8 to 9m thick, while the outer is striated or granular. Fuhrmann described a cuticula only 7^ in thickness and divided into two layers, and Solowiow gave the thickness of the "homogeneous cuticula" as 23//. Minckert (1905a :402) said that the comidian or pseudociliated layer, present in many bothriocephalids, was quite evident in S. nodosus but absent on the posterior borders of the proglottides. Here the cuticula was found to be 15ju in thickness, excepting on the posterior borders where it is only Sji, and divisible into two layers, the outer of which, a little thinner than the inner, was much lighter, granular in consistency or somewhat striated with, however, a more or less uniform external boundary. It seems to be easily separated from the inner stratum, the bounding line, in reality the innermost portion of the external layer, being in most places very light. In fact the brightness of this inner layer of the outer stratum indicates the degree of separation of the two layers in the process of sloughing off the outer, which can be easily followed in sections as described by Kiessling. This description however, applies only to the adult stage. In larvae the cuticula, altho of the same thickness, shows an outer decidedly pseudociliated layer only Ay. in depth. The subcuticula, 88.5At in thickness in the median line according to Solowiow, was found to be from 40 to about 65ai, Kiessling having given the limits as from 29 to 38/:x. While the parenchyma is as described by the 325J PSEUDOPHYLLIDEA FROM FISHES— COOPER 37 authors, very fine meshed, calcareous bodies are present in comparatively small numbers, particularly just beneath the subcuticula of the larva. Their maximum dimensions are 23 by 13)u. The musculature has been well described by Kiessling and Fuhrmann, so that it needs only to be added that in sections of mature proglottides the outer- most layer of transverse muscles as well as the outer longitudinal layer are much less numerous and hence well defined than in the larva. Whereas Kiessling gave the thickness of the external and internal longitudinal groups, which on account of their compact nature were found to be more uniform in thickness than the transverse layers, as 8 to ZZ and 16 to 49ju, respectively, and Fuhrmann as 4 and 8^, the writer found them to be 17 and 30 to 40^1. The nervous system was first studied in detail by Niemiec (1888:9) and later more thoroughly by Cohn (1898:126) who summarized its structure in the following words: "Von dem vordersten Theil, den Ganglien und der Commissur, ziehen die Hauptstrange und 12 Nebennerven riickwarts [six associated with each chief strand]. Die Nebennerven theilen sich dichoto- misch in zwei Ebenen, der frontalen und radiiiren, ein Theil des Theilfasern riickt zwischen aussere Transversal- und Langsmuskeln, der andere bleibt weiter nach innen zu zuruck, und diese Nerven treten einerseits unter einander durch Ringcommissuren, andrerseits durch radiare Fasern mit den Haupt- nerven in Verbindung. " Kiessling gave the diam.eter of the chief nerve strands as 38/i and Solowiow as 67.9;u; here they were found to be from 30 in mature proglottides to 75/z in the anterior segments. The gangUa have a diameter of from 55 to ^5p., as compared with 77ju of Kiessling. In transections from 25 to 30 excretory vessels appear in the medullary parenchyma with diameters ranging from 29 to 63/i. Fuhrmann gave 24 as the number, while Solowiow gave their size as 13.9 to 23.3ju. Foramina secun- daria pierce the cuticula here and there, but they are not very numerous. As indicated in the diagnosis of the subfamily the reproductive organs appear close behind the scolex. In one toto preparation of a larval specimen, number 72 of the above table, the earliest traces of their rudiments were present in the 18th proglottis, or 3.96mm. from the anterior end, while in the only mature specimen, H.7, they were in the 16th proglottis, a few eggs appearing in the uterus of the 17th. The cirrus and vagina open close together in a very shallow and sometimes quite obliterated genital cloaca having a maximum diameter of about 90^, the vagina behind the cirrus, but only very slightly either to the right or left and not according as the uterine opening further back likewise alternates irregularly but with a greater amplitude. The three apertures form almost a right-angled triangle, as described by Kiessling; but, as was pointed out by Llihe (1899a:716) this arrangement is by no means con- stant but varies with the state of contraction or relaxation of the whole 'itrobila and hence cannot be considered as specific. The testes are arranged in a single layer in the dorsal portion of the medulla not only in the larva but also in the adult, as described by Fuhrmann, the majority of the excretory vessels being situated towards the ventral side of the 38 ILLINOIS BIOLOGICAL MONOGRAPHS [326 medulla. They are absolutely continuous from proglottis to proglottis. Their number in transections is from 30 to 40 (30 to 35, Kiessling) and in sagittal sections from 8 to 12 for each proglottis, thus making the total from 240 to 480 or over 300 on the average, which stands in distinct contrast with the number of about 100 given by Fuhrmaim. The latter also gave their dimensions as 80 by 34;u, Kiessling as 16 to 66/i in young and 149/x in mature animals, and Solo- wiow as 68 to 93/x. The writer found them to be from 85 to 100/x in depth, 40 to 65/1 in width and 55 to 85/i in diameter. They are, as indicated by their num- bers, very closely crowded together in the proglottis. The vas deferens forms a compact mass of coils situated in the median line dorsally and slightly pos- terior to the vesicula seminalis to which it is closely applied as a sort of cap. While the diameter of the w^hole organ is about 0.3mm. that of the duct itself varies from 35 to 60/u when distended with spermatozoa. Kiessling gave its diameter as 38ju and Solowiow as 16.3/i. The large thick- walled seminal vesicle (Fig. 80) situated immediately above the cirrus-sac was found to have a maxi- mum depth of 175ju and transverse diameter of 150/x, as compared with the 92ju of Kiessling and the 80)U of Fuhrmann. Its walls are very muscular, about 25/i in greatest thickness, and covered both internally and externally with numerous nuclei which are respectively epithelial and parenchymatous or myoblastic in their nature. Within the cirrus-sac the vas deferens is much coiled but not enlarged to form any secondary vesicle nor sharply separated into an ejaculatory duct and cirrus proper. The sac itself is oval in shape, the ventral end being the smaller, and the proximal end somewhat invaginated by the seminal vesicle. Its size is shown in the following table: KIESSLING FIIHRMANN SOLOWIOW THE WRITER Depth 0.347mm. 0.25mm. 0.204mm. 0.185 to 0.203inm, Width 0.192mm. 0.12mm. 0.174mm. 0.203 to 0.212mm, Length 0.166 to 0.185mm, Its wall about equal in thickness to that of the seminal vesicle is, however, more open in texture, the myoblastic nuclei of the obliquely arranged muscle fibres being scattered thruout its diameter (Fig. 80). It is furthermore, not sharply separated either externally or internally from the surrounding parenchyma nor the numerous stout retractor muscles of the cirrus, respectively. The latter, in fact, constitute practically the whole of the contents of the sac apart from the duct itself. The only protruded cirrus seen had a length of 70/i, as compared with the 0.3945mm. given by Solowiow. The vagina, the opening of which is usually situated about 50^i from that of the cirrus at the bottom of the shallow genital cloaca above mentioned, has a diameter of from 45 to 60/i at the first bend in its course within the medullary parenchyma. Soon after it enters the latter it becomes thin-walled, as pointed out by Fuhrmann, owing to the thinning out of the cuticula and the substitu- tion of the proximal nucleated epithelium for the same, altho more peripherally much flattened nuclei are to be seen beneath the cuticula and crowded close to the basement membrane. In other words the gradual replacement from 327] PSEUDOPHYLLIDEA FROM FISHES— COOPER 39 within outwards of the cuticula for the original epithelium may be followed very easily in the walls of the vagina. The duct gradually enlarges to form a much elongated receptaculum seminis (Fig. 79) with a diameter of 92 to 104/i (9 to 21)u, according to Kiessling!) and sharply separated from the spermiduct, which, however, was not found to unite with the oviduct close to thei dorsal transverse musculature as stated by Fuhrmann, but close to the ventral wall of the medulla. The ovary consists of two large wings (Fig. 79), composed of closely crowded tubules, lying immediately upon the ventral transverse muscles and united by a much smaller isthmus, the whole having a width of 0.64mm. as compared with the 0.28mm. of Solowiow. The average length and depth of the wings are, respectively, 105 and 90/x. Ova from the isthmus and more median portions of the wings of the ovary have a diameter of 13ju while their nuclei are 5/x. The respective measurements by Kiessling and Solowiow are 9 and 6/x and 13.9 to 23.3)Lt and 1 .5 to 2/x. Fuhrmarm stated that one of the most important differences between his Sch. zschokkei and Sch. solidus was the pre- sence in the former of an oocapt, but Liihe (1899a:717) claimed that this structure was in all probability overlooked by Kiesshng. It arises from the posterior aspect of the isthmus almost in the median hne with a diameter of from 35 to 40ju. The oviduct, according to Kiessling has a diameter of 13, or to Solowiow of 27/u; here it was foimd to be from 25 to 30jli between the entrance of the vagina and that of the common viteUine duct, which two points are close together as in L. intestinalis. The common viteUine duct enlarges some little distance from its opening into the oviduct to form a vitelUne reservoir having a diameter of 30^ (23;u, Kiessling). The vitelUne folUcles are extremely num- erous and closely crowded together in a layer with a maximum thickness of 85/Lt, situated between the inner longitudinal and middle transverse muscles (Fig. 79). They are continuous at the margins of the proglottis as they are from joint to joint, and are broken only in Umited elliptical areas above and below the reproductive ducts in the median line, as stated by Fuhrmarm. The dimensions of the individual follicles are from 58 to 87 by 18 to 26/i, the larger dimensions being the dorsoventral diameters, — 56 to 107 by 56/i, ac- cording to KiessUng, and 18 by 27/i after Solowiow. Just beyond the entrance of the common viteUine duct the oviduct enlarges to form the ootype with a diameter of 16/x (20/x, Kiessling) which is surrounded by the shell-gland, situated just above the median frontal plane and somewhat lateral. Thru- out its course the oviduct is lined with an epithelium in which prominent nuclei but no distinct cell boundaries appear and from which numerous cilia protrude into the lumen. In the ootype these cilia are much more noticeable. From the ootype the oviduct passes ventrally with a few coils, then across the median line close above the receptaculum seminis as the beginning of the uterus. The latter gradually enlarges as it passes forward across the median line several times, until at about the middle of its course it has a diameter of 85 to \oSn. As regards the terminal portion of the tube it was found that, as Fuhrmann observed: "Der Endtheil der Uterus verengert sich und ver- laiift von der Dorsalflache [the median frontal plane in which the last trans- 40 ILLINOIS BIOLOGICAL MONOGRAPHS [328 verse coil is situated] direkt ventral, um regelmassig abwechselnd links oder rechts neben der Vagina auszumlinden. " Sections show that the actual opening is formed by the rupture of the bot- tom of a cup-like invagination of the cuticula from the ventral surface, which meets the end of the duct with a diameter of from 25 to 40^1. As Fuhrmann stated, "Dieser Ausfiihrgang der Uterus ist von der Stelle an, wo er ins Rinden- parenchym tritt, wie die Vagina und der Cirrusbeutel, von zahlreichen Paren- chymmuskeln umhiillt und von einer der Korpercuticula ahnlichen Membran ausgekleidet;" but the cuticula seems to appear as such only near the opening, since only half-way back along this dorsoventral limb of the organ flattened nuclei are distinctly seen. In other words the flattened epithelium of the uterus, which, showing only a few scattered nuclei, was described by Kiessling as a "fine, structureless but elastic membrane," passes insensibly into the cuticula near the opening, no distinct line of junction between the two being discernible. This latter statement is likewise applicable to the similar struc- ture of the vagina. The dimensions of the ellipsoidal eggs in the sections of the uterus were found to be 62 to 65 by 33 to 36;u. KiessUng gave them as 49 by 37/i and Fuhrmann as 70 by 29/i. In discussing the latter, however, Liihe (1899a :7 18) remarked that not only did he find variations from 38 by 22 to 56 by 38/i in the size of the eggs in material of B. zschokkei sent to him by Fuhrmann, but that in general even greater variations than these are to be found in other spe- cies according to the various writers. Our knowledge of the life-history of this species dates from the time of Abildgaard (1790) who, as mentioned above, was the first to experiment with the larval individuals found in fishes. Creplin (1829) united the two forms which were considered to be two separate species into one species, evidently on the basis of the previous work, especially Abildgaard's (cf. Donnadieu, 1877:340), while Donnadieu in his elaborate experiments on the life history of Ligula unfortunately did not differentiate between it and Schistocephalus. The development of the fertiUzed embryo into the oncosphere was first studied by Willemoes-Suhm (1869) and later more in detail by Schauinsland (1885:555), since when nothing of special importance has been added, so far as the writer is aware. Hence up to the present nothing is known about the development of the oncosphere into the larva in the intermediate host, as is indeed the case with most of the bothriocephalids. As regards the identity of the material studied with the European species it will be seen from the above comparisons that, while there are many dis- crepancies among the data given by Kiessling, Fuhrmann and Solowiow, those by the latter departing the farthest in many respects, the resemblances so out- weigh the differences as to make the erection of a new species unjustifiable. The thickness of the cuticula, the diameter of the excretory vessels, the dimen- sions of the seminal vesicle, the ovary and the eggs, which constitute the majority of the differences, might easily be explained by differences in age of the material studied. But the number of testes (100) as given by Fuhrmann 329] PSEUDOPHYLLIDEA FROM FISHES— COOPER 41 can scarcely be reconciled with that given here (300+ ), altho his dimensions of the organs agree with these perhaps better than do those by KiessUng or Solowiow. On the other hand there is another factor which may be in the long run more important than a comparison of the details of the anatomy of this evidently highly variable species, namely, the geographical distribution of the hosts. Altho little emphasis can be placed on Fabricius' finding T. gasterostei in the type larval host as long ago as 1780 in Greenland, it must be remembered that here in America there are, as in the case of L. intestinalis, a number of not only the same genera but also of the same species of the larval as well as of the adult hosts as in Europe. From this alone one would be justified in expecting to find the same species of Schistocephalus here, especially since it infests such a number of different host species. But it is a very surprising fact that apart from Linton's report of the larva from Montana evidently no one has up to the present found the form in any of the numerous fish-eating birds of the continent. This evident infrequent occurrence of the species is illustrated by the fact that the material used for the present study consisted of only five lots: Nos. 61b and 72 from the body cavities of Uranidea formosa, taken from the stomach of Lota maculosa, and 190 from the coelom of Gasterosteus bispinosus atkinsii, of the writer's collection; one lot from Gasterosteus cataphr actus from Alaska; and No. 17.192 of the collection of the University of Illinois from the intestine of Lophodytes cucullatus, the only mature specimen available. 42 ILLINOIS BIOLOGICAL MONOGRAPHS [330 HAPLOBOTHRIINAE Cooper 1917 Strobila formed by the subdivision of the segments of a primary strobila. Scolex of the latter a cylindrical, somewhat club-shaped organ bearing four eversible proboscides similar in structure to those of the Trypanorhyncha ; scolex of the secondary (definitive) strobila merely the sUghtly modified fore- most segment, provided With shallow dorsoventral depressions analogous to the bothria of other bothriocephaUds. An elongated neck may be said to be present in the primary strobila. Segmentation of the primary strobila result- ing in the formation some distance behind the scolex of a comparatively small number of long, narrow segments which in turn subdivide anteriorly to form the segments of the secondary strobila. Segmentation in the latter thus beginning immediately behind the secondary scolex, but complete in its anterior region only. Genital organs simple in each proglottis. Genital openings surficial, ventral and median as in the Diphyllobothriinae. Ovary and shell- gland median, respectively ventral and dorsal. Vitelline follicles in the medul- lary parenchyma, as are the testes, both within the nerve trunks. Testes separated into two lateral fields by the median excretory vessel and the genital organs in the median line. Vas deferens enlarged to form a large non-muscular seminal vesicle before entering the cirrus-sac. Cirrus armed with minute spines. Receptaculum seminis medium sized, sharply separated from the spermiduct. Uterus divided into a much coiled, proximal uterine duct and a large uterus-sac, as in the Ptychobothriidae. Type genus: Haplobothrium Cooper. Altho as yet comparatively little is known about the Ufe-histories of the bothriocephaUds, it has been shown that the definitive scolex and strobila develop directly from the larval stage, known as the plerocercoid, which is present in the intermediate host. This is certainly the case with Ligula, Schistocephalus, Diphyllobothrium latum, Cyathocephalus truncatus and Tri- aenophorus. As a matter of fact in all of these the scolex is more or less well formed before the larva reaches the final host; and after that the plerocercoid continues to grow and soon shows the beginnings of segmentation which mark the young strobila. Consequently the writer feels that what in the present paper is called the primary- strobila of Haplobothrium must be looked upon as the true strobila, homologous to the young strobila of other bothriocephaUds. This is contended in spite of the fact that what was formerly considered (Cooper, 1914, 1914a) to be the strobila is quite similar, apart from the absence of external segmentation in its posterior region, to that of other members of the order. Even tho it is provided with a very aberrant scolex region — and the scolex is no more sharply set off from the rest of the larva in other species, such as D. latum — the young imsegmented primary strobila may be considered to be a typical plerocercoid. The nervous system is t>'pical in that it consists of two chief strands united anteriorly by a commissure. The relatively large size of the latter, however, 331] PSEUDOPHYLLIDEA FROM FISHES—COOPER 43 seems to be due to the proximity of the highly specialized proboscides to which it sends large branches. The excretory system is likewise built on the t^'pical plan, the posterior connections with the exterior being, in fact, quite like those of B. scorpii. On the other hand, the terminations of the nervous and excretory systems in the secondary strobila, both anteriorly and posteriorly support the view that the latter is not homologous with the strobila of other bothriocepha- lids. What was formerly described as the ring commissure must now be con- sidered as merely a secondary formation due to the fusion of the severed ends of the chief strands ; which statement is also applicable to the terminal vesicle of the excretory system. And this, in spite of the fact that the secondary scolex is quite similar to the true scolex of other forms in that it is supplied with two sets of muscles which are not found in the foremost segments, but are peculiar to the scolex. Since there is considerable evidence in the literature on cestodes to show that the prominent posterior borders of the foremost segments of many species are developed as accessory organs of attachment or for locomotion (cf . Spengel, 1905:281), the question might well be raised whether external segmentation in Haplobothrium is paUngenetic or cenogenetic in its nature, particularly since it is confined to the anterior region of the secondary strobila. The facts that no such appendages are present in the primary strobila and that the posterior end of the secondary one is not segmented, apart from the consecutive sets of genitalia, would seem to point to the original condition being one in which external segmentation was absent as in Ligula or Triaenophorus. Since, however, in the middle region of the secondary strobila there is an actual correspondence between the external and the internal segments, it is quite probable that the external segmentation is much older than might at first appear, while the ligulate condition of the posterior end may have developed secondarily. It is well to remember, too, in this connection that according to Liihe (1898:285) Ligula has descended from fully segmented bothriocephahds. The subfamily, which up to the present contains only one genus and one species, bears a general resemblance to the Diphyllobothriinae. It differs from the latter, however, in that the genital organs are simple in each proglottis; the viteUine follicles are medullary; the testes are within (i.e., medial to) the nerve trunks; the seminal vesicle is not strongly muscular; the cirrus is armed with minute spines; the receptaculum seminis is medium sized; while the uterus is divided into a uterine duct and uterus-sac as in the Ptychobothriidae. HAPLOBOTHRIUM Cooper 1914, e. p. Haplobothrium Cooper 1914:1-2, 1914a:115 Borders of the terminal disc of the secondary scolex and of the posterior auricular appendages of both scolex and anterior segments provided with min- ute spines which disappear with the appendages farther back. Nervous system consists of two chief strands situated in the medullary parenchyma outside of the vitelline follicles, uniting in the anterior end of the secondary strobila to form a secondary nerve ring, and eight collateral strands, four arranged around 44 ILLINOIS BIOLOGIC A L MONOGRAPHS [3 ?] each main tract, the latter in the jointed portion of the strobila only, but in the true scolex to form an irregular transverse commissure situated among the pro- boscides. Excretory system composed of one large median and slightly dorsal vessel and two smaller lateral and ventral, all uniting in the secondary scolex behind the nerv^e ring to form a vesicle. No genital cloaca; opening of vagina close behind that of cirrus, towards the anterior end of the proglottis, that of the uterus much farther back. Sphincter vaginae present. Vitelline glands in numerous follicles arranged cylindrically around the testes, both continuous from proglottis to proglottis, leaving clear areas opposite the central genital ducts; large vitelline reservoir. Vas deferens provided with a sperm-reservoir at its posterior end near the middle of the proglottis; whole of the course of the duct dorsal to the uterus-sac. Uterus-sac when gravid occupies the whole of the middle of the proglottis. Type and only species: H. globtdiforme Cooper. The genus is here emended owing to the elevarion to subfamily rank of a number of the characters given in my original generic description. HAPLOBOTHRIUM GLOBULIFORME Cooper 1914 [Figures 9, 10, 43, 44, 65-67] 1914 Haplohotkrium globidijorme Cooper 1914:2, 1914a:115 Specific diagnosis: With the characters of the genus. Small worms, pri- mary strobila up to 70mm. in length, secondary to 110mm., with respective maximum breadths of 0.3 and 0.6mm. Primary scolex 0.35mm. in diameter, indefinite in length, bulbs 0.40 to 0.45 by 0.06 to 0.07mm.; secondary scolex, 0.4 to 0.5 by 0.25 to 0.4mm. Auricular appendages disappear at about the 25th segment in normal secondary strobilas. Foremost secondary segments tet- ragonal, middle and posterior much elongated and considerably depressed. Cuticula 3 to 4;u in thickness, subcuticula 25m. Chief nerve strands 18pi in diameter, narrowing intersegmentally. Terminal excretory vesicle 20 to 40m in diameter. Genital organs begin at about the 15th proglottis. Opening of cirrus and vagina 0.02 to 0.07mm. apart. Testes spherical to ellipsoidal in shape, 70 to 115^ in maximum length; about 80 in each segment. Vas deferens median, elongated, only slightly coiled, 10 to 55m in diameter. Vesicula seminalis broadly spindle-shaped, 140 by 90m. Cirrus 20 to 30m in diameter; cirrus-sac, 0.16 to 0.21 by 0.14 to 0.16 by 0.18 to 0.20mm. Vagina 20 to 30m in diameter at its opening, 56m in its enlarged distal por- tion. Receptaculum seminis 30 to 45m in diameter, spermiduct 5 to 10m and very muscular. Ovary hippocrepiform, the limbs directed posteriorly and often fused with each other, the isthmus narrow. Ova from latter 10 to 12m in diameter, their nuclei, 7m. Oocapt 15 to 25m in diameter, oviduct 8 to 15m. 333] PSEUDOPHYLLIDEA FROM FISHES— COOPER 45 Two vitelline ducts, each 6ju in diameter; vitelline reservoir 25 to 55/x; follicles spherical or ellipsoidal in shape, 8 to 50/z in diameter, very numerous and closely crowded. Ootype 20^1 in diameter; shell-gland irregular in shape, poorly developed. Uterine duct enlarged proximally with few coils, smaller distally and more coiled, median, 25 to 55/i in diameter; uterus-sac elongated, fiUing most of the medulla when gravid; uterus opening a small median elongated slit, situated near the posterior end of the sac. Eggs, 60 to 70 by 40 to 43^. Habitat: In the intestine of Amia calva L. HOST LOCALITY COLLECTOR AUTHORITY Amia caha L. (tjT)e host) >» >> M )» Go-Home Bay, Muskoka, Ontario Havana, Illinois Fairp)ort, Iowa A. R. Cooper H. B. Ward Cooper 1914a : 81 Cooper (the present paper) 1) Type specimen: No 33.1 in the writer's collection. Co-types: Nos. 33.2 and 33.3 of the same, in the collection of the University of Illinois In a preliminary paper on the systematic position of this species the writer (1914:1) described the scolex as ". . . unarmed, although the edges of the terminal disc and auricular appendages of both scolex and anterior proglottides are provided with very minute spines. Bothria, two shallow depressions on the dorsal and ventral surfaces, ver\^ simple in structure, " and in the detailed description which followed (1914a) the organ was dealt with as follows (p. 82): "The scolex is quite small, simple externally, and with the unaided eye can scarcely be distinguished from the first joints. It is shaped roughly like a rectangular solid, hollowed out laterally to form simple depressions and dorso- ventrally the shallow bothria or organs of attachment. The summit is some- what prolonged as a low pyramidally-shaped disc, quite comparable to that (" Scheitelplatte ") found in the members of the subfamily Triaenophorinae Luhe 1899. . . . The opposite end of the scolex is modified to form two pairs of auricular appendages closely resembling internally as well as externally those of the foremost joints. " Furthermore, in both papers it was emphasized that the scolex differs Uttle in structure, apart from the nervous and excretory systems, from the first segments, and that the simple bothria seem of Httle functional importance as compared to those of other species while the auricular appendages of both scolex and foremost joints with their borders of minute cuticular spines probably act as accessory organs of attachment. Since then the latter view has been rendered still more highly probable, altho as yet no observations have been made on the hving worms in their relation to the wall of the host's intestine, by the discovery that the so-called scolex (Figs. 9 and 10) is not in reahty the scolex but only a sUghtly modified anterior segment. The true scolex is somethmg quite different from anything present in the whole order so far as the writer is aware. As shown in figures 43, and 44, it con- 46 ILLINOIS BIOLOGICAL MONOGRAPHS [334 sists of the slightly enlarged anterior end of the original plerocercoid or larva from which protrude four proboscides, the whole somewhat resembling a hydra and at once reminding one of the Trypanorhyncha. As will be presently seen the latter comparison is a very apt one. Each proboscis consists of a per- manently protruded base or stump, as indicated in figure 43, about 85^ in length and 45 to 55/i in diameter, and an eversible proboscis proper having about the same diameter. The former is somewhat conical in shape and thickly set with minute, posteriorly directed cuticular spines which pass on to the neighboring portions of the scolex for a short distance. The whole forms at first sight a continuous tentacle gradually diminishing in size to the pointed end. These tentacles attain a length of 0.35mm., including the base, when fully evaginated, and are directed almost at right angles to the longitudinal axis of the larva, their bases being, however, turned slightly forward (Fig. 43). Within the scolex the tentacles are accommodated in elongated cylindrical muscular sacs which are quite comparable in structure to the bulbs of the Trypanorhyncha. These (the sacs) lie freely in the loose parenchymatous tissue in the diagonal diameters of the region. When the proboscides are invaginated, they have a length of 0.45mm. with a diameter of 0.07, or 0.40 by 0.06 when the tentacles are protruded. The walls of the bulb (Fig. 67) are composed of two thick layers of muscles, an outer longitudinal or somewhat obUque — much the heavier of the two — and an inner circular, and a cuticula- like lining, on the inner border of which in transections numerous flattened nuclei appear. The walls are attached to the edge of the stump, and these layers have the same relative arrangement as that of the cuticula and cuticular muscles on the outside of the body, only being in the reverse order. Con- tinuous also with the edge of the stumps are the walls of the proboscis proper, which consist of a thin external layer of cuticula and only feeble cuticular mus- cles. Attached to the wall internally thruout its course are the retractor mus- cles of the proboscis which pass backward and become attached to the posterior end of the bulb. These can be seen best in longitudinal sections where the proboscis is retracted, for then they are closely crowded and much thicker, and their attachment to the inner end of the proboscis is nicely shown. In the retracted condition the latter is, of course, hollow, the narrow cavity often triradiate in transection (Fig. 67) being easily followed into the bulb for about one-third of its length. Closely apphed to the cuticula of the tip of the pro- boscis appear in some cases gland-like cells taking the counterstain quite like those behind the bulbs to be described below. They are shown in figure 67. Apart from the structures abready described, the contents of the bulbs and consequently of the proboscides to a certain extent, consist of a small amount of loose parenchymatous tissue and what is evidently a good deal of nervous tissue coming into the Dosterior end of the organ. Evagination of the proboscides is evidently brought about by the contrac- tion of the muscles in the walls of the bulbs, but the body wall in the vicinity of the latter probably greatly assists since its musculature is well developed. Some distance behind the posterior ends of the bulbs the latter consists of a 335] PSEUDOPHYLLIDEA FROM FISHES— COOPER 47 ring-like layer of loosely arranged main longitudinal fibres occupying the middle one-third of the radius of the nearly circular cross-section; no trans- verse fibres; but comparatively strong cuticular muscles, of which the inner longitudinal layer is the more pronounced. Farther forward this main longi- tudinal group gradually gives off small fibres towards the cuticula as they them- selves diminish in number and size, until at the level of the hinder ends of the bulbs only a few of the latter fibres are left just beneath the subcuticula. An outer series at the same time forms a compact layer situated close to the longi- tudinal cuticular fibres (and hence outside of the subcuticular nuclei) but separated from them by a thin stratum of circular fibres. And this continues to the tip of the scolex, most of the remaining inner longitudinal muscles being located at the ends of the transverse and dorsoventral diameters of the transec- tion. In the region of the bulbs the body wall is thus quite muscular, and in all probability assists the bulbs in evaginating the proboscides by compressing the whole of the parenchyma surrounding them. Between the bulbs and right beneath the tip of the scolex a few transverse and sagittal fibres are to be found, while just beneath the bases of the stumps of the proboscides the outer longi- tudmal muscles unite with the longitudinal cuticular fibres to form O-shaped loops surrounding the diagonal quadrants of the scolex which accommodate the bulbs. These loops are evidently for the control of the direction of the proboscis stumps. Owing to the fact that, as originally stated by the writer (1914a:96), "there is a more or less definite point in the strobila, at or about the 15th proglottis, ahead of which the genital organs do not seem to develop and behind which in older strobilas they appear very quickly, " and the further fact that not only do the auricular appendages of the posterior ends of the proglottides disappear at about the same place constantly, namely, at about the 23rd or 24th segment, it might seem that the (secondary) strobila is composed of a more or less definite and predetermined number of segments. But this is not the case, as will be seen presently when the method of formation of new proglottides is described. As a matter of fact segmentation in this species is carried on after an entirely novel plan, involving the formation of not only new segments but whole chains of them or, indeed, whole strobilas from the original larval or primary strobila as it is here called. The original larva which resembles the bothriocephalid plerocercoid, excepting for the peculiar scolex, gradually elongates with growth, until between a length of 4 or 5mm. the first traces of segmentation appear in the hinder ends of cleared specimens as feeble aggregations of nuclei forming faint dark lines at regular interv^als. In one specimen 4.8mm. in length five intervals were made out, the second last of which was 0.37mm. in length by 0.20mm. in diameter, while the last one was shghtly larger and rounded posteriorly. These primary segments elongate with the growth of the strobila, and the constrictions between them gradually deepen as their anterior and posterior ends enlarge slightly, the former relatively faster than the latter. When a total length of strobila of about 10mm. is reached, the hindermost segment. 48 ILLINOIS BIOLOGICAL MONOGRAPHS [336 itself now about 1.5mm. in length, begins to show faint transverse lines in its anterior end, decreasing in intensity from ahead backwards. These are the earliest traces of the divisions of the primary segments into the secondary seg- ments which will become the definitive joints of the anterior ends of the adult strobilas. In other words the original primary larva, plerocercoid or strobila, divides up into secondary strobilas which eventually separate from each other and grow into the adult chains as described above for the species. But long before separation takes place the entire development of the anterior segments with their characteristic posterior auricular appendages and the formation in particular of the first segment can be followed in these primary strobilas (Fig. 44). Whereas originally (Cooper 1914a:82, Figs. 5 and 6, PI. V) attention was drawn to young scoUces with only 5 to 8 segments, it was found in connec- tion with the present study that the latter number, about 8 in external view or 16 or 17 in cleared specimens, is in reality that developed by the secondary strobilas before detachment from the original chain. The smaller strobilas are now looked upon as having been prematurely and accidentally separated from the posterior end of the primary strobila. The attachment soon be- comes very slight, owing to the rapid deepening of the constriction ahead of the first segment, so that some time before the auricular appendages of the lat- ter are fully delimited posteriorly very little manipulation of even alcoholic specimens, let alone cleared ones, suffices to break up the chain. However, there was found intact in the material at hand one primary strobila 88mm. in length, showing twenty secondary strobilas, including the undifferentiated anterior segments from which they are developed. Furthermore, the last two of these, 10.4 and 11.5mm. in length, showed in their posterior unseg- mented portions the earliest traces of the rudiments of the reproductive or- gans. As has been already intimated the anterior segments form within the secondary or definitive strobilas by a gradual demarcation from head back- wards, first internally in the parenchyma — actually as transverse layers of nuclei (Fig. 44) which will eventually form the posterior auricular appendages — and then externally as shown in the figure. A continued search for evidence in connection with the question of whether or not there is in the secondary strobila a definite number of segments (external and genital combined) brought out further interesting facts. The number was counted in several young strobilas, evidently not long separated from the primary strobila, with the following results in the case of four typical speci- mens: (1) Length, 19mm., number of segments, 45; (2) 27mm., 29 or 30; (3) 26.5mm., 30 (the posterior ones here ripe as in the next specimen); (4) 41mm., 32 segments. It would seem from these data that there is a more or less definite number of segments, which might be considered to be about 30. But in No. 3 segments 9, 10 and 11 were not only much elongated but further subdivided anteriorly; while in No. 4 similar conditions were present in seg- ments 10, 11 and 12, excepting that in the case of the eleventh the aggregations of nuclei indicating the subdivisions were in the posterior end. Similar elonga- ted segments in still other strobilas show this condition in their middle regions. 337] PSEU DOPEY LLIDEA FROM FISHES— COOPER 49 Thus there is a tertiary subdivision of the secondary segments, which must, however, be considered as by no means as regular as the secondary subdivision of the original primary segments. These facts explain the aberrant nature of the strobila in this region, noted formerly by the writer, and the presence in material of chains showing anteriorly very young segments similar to those formed in the oldest attached secondary strobUas but posteriorly much older segments with well-developed auricles and farther back the typical mature proglottides of the ordinary strobila. Consequently it is probable that there is not a definite number of segments formed, but that further, irregular and evidently indefinite subdivision, resulting in the formation of an inconstant number, takes place chiefly in the middle portion of the anterior segmented region of what now must obviously be called the secondary strobila. In the Hght of this method of segmentation certain facts in connection with the nervous and excretory systems that were previously considered to be very unique, to say the least, will now be expUcable. In primary strobilas, even those that are youngest, the excretory system consists, as in tne adult, of a larger median vessel and two lateral vessels which run backward and unite in the posterior end to form a plexus from which very many smaU vessels pass to the exterior by prominent foramina secundaria piercing the cuticula, much as described by Fraipont (1881:11, Fig. 7, PI. II) for Bothriocephalus scorpii. In the yovmgest larva I have been able to find only the median vessel, which becomes greatly reduced in diameter about twice the length of the bulbs from the anterior end is present in the scolex. It forms a simple plexus among the bulbs anteriorly. In primary strobilas, however, in which segmentation has gotten well under way, all three vessels are quite prominent. They pass close to each other as well as to the chief nerve strands, when they traverse the constrictions between the developing secondary strobilas, where the median vessel is somewhat enlarged. As they near the anterior end of the worm they give off numerous branches of their own calibre, and when they meet the large ganglionic mass described below, diverge as four vessels (two on each side) and continue lateral to the bulbs to the tip of the scolex. Here after forming an open plexus among the anterior ends of the former, they unite in a single median frontal loop. As the constrictions between the secondary StrobUas deepen all three vessels likewise become gradually constricted until eventually they are cut off, and the adult conditions are subsequently developed by the simple process of the turning in of both severed ends. And since in these younger forms the median vessel is considerably enlnrged at the region of constriction, it remains thus in the hinder end of tlie adult strobila as well as in the first segment — as described and figured elsewhere by the writer (1914a:93, Figs. 12, 37)— while in the latter it is joined by the lateral vessels to form the characteristic terminal vesicle. The nervous system of the primary strobila consists of two chief strands passing thruout the segments, a quite irregular commissure connecting them anteriorly, and a very large gangUonic mass situated some distance posterior to the proboscis bulbs. The chief nerve strands, which are quite indistinct 50 ILLINOIS BIOLOGICAL MONOGRAPHS [338 at different levels but constantly located in the median frontal plane, diverge as they meet the ganglionic mass in passing forward, and consequently oppo- site the bulbs come to lie close to the subcuticula laterally (Fig. 65). About 0.2mm. from the tip of the scolex they are united by a very irregular but com- paratively large transverse commissure, from which large trimks pass to the neighboring bulbs both forward and backward. This commissure has a length or longitudinal diameter of about O.lOmmi., while its maximum depth between the lateral pairs of proboscides is about 40ju. It gives off large branches anteriad to the lateral walls of the bulbs and caudad to the central walls. In the latter case a large branch leaves the median portion of the com.missure, which is incidentally freely pierced with excretory vessels on each surface, and shortly divides into two, each supplying the central walls of one of the frontal pairs of bulbs (Fig. 65). The anterior branches likewise arise in a common tiaink on each side, which is in reality the continuation of the lateral ganglionic enlargements of the commissure, but they supply the outside walls of the lateral pairs of bulbs. Imbedded in the commissure are numerous nuclei which, on account of their larger size than the neighboring parenchymatous nuclei, are probably ganglionic or nervous in their nature. Just behind the posterior ends of the bulbs and extending from 0.8 to 0.9mm. farther backwards (Fig. 43) there is a large mass of large nucleated cells which in transverse sections (Fig. 66) is seen to occupy the whole of the micduUa (and about the whole of the section) excepting for the excretory vessels. These cells are roughly spherical in shape and have a maximum diameter of 25)u, their nuclei being 5ju. On account of their finely granular consistency and their taking the counterstain quite like the anterior nervous commissure they were interpreted as being ganglionic cells. And this view was supported on closer study by the discovery that they are not only united laterally with the chief nerve strands (Fig. 66), which can scarcely be distinguished from them at various levels, but with each other thru a comphcated plexus of fine longitudinal strands which pass forward to- wards the bulbs and form around their bases an almost solid mass of fibrils (Fig. 43). From this mass large strands from 10 to 15m in diameter pass into the bases of the bulbs, one for each, and are distributed among the retractor muscles of the proboscis which they evidently supply. In the youngest primary strobilas but not in the older ones, this mass of fibrils at the bases of the bulbs evidently connects forward by a few strands with the commissure. Just as the definitive form of the anterior and posterior ends of the excre- tory system is explained by the separation of the secondary strobilas and the subsequent growing over of the ends, so is that of the nervous system, particularly anteriorly. As was noted by the writer (1914a) in connec- tion with the preparation of the original description of this species and shown in figure 11, the nerve-ring is drawn out anteriorly into a point which is directly opposite a small conical pit in the tip of the scolex. This fact, as well as the relatively small size of the nerve-ring, is explained by the contraction of the free end of the "scolex" after separation and the growing together of the ends of the nerve strands to form the ring. The close association of the nerve-ring 339] PSEUDOPHYLLIDEA FROM FISHES—COOPER 51 and the terminal excretory vesicle is also comprehensible in the light of this method of development, for, since the nerve strands are situated close outside the lateral excretor\' vessels at the constrictions, they simply turn in towards the median line and unite immediately ahead of the junction of the latter with the median vessel. As will be gathered from the foregoing description there is a most remark- able resemblance between the scolex of H. globuliforme and that of the Try- panorhyncha not only in the structure of the proboscides but also in the pre- sence of the large mass of ganglionic cells associated with them posteriorly. Each proboscis consists of three parts: (1) a hollow tentacle, capable of eva- gination, (2) a short permanently protruded stump, armed v/ith thickly set minute, cuticular spines, and (3) a comparatively elongated bulb. Of these parts (1) and (3) may be compared respectively with the proboscis and the bulb of Tetrarhynchus or Rhynchobothrius. The proboscis, altho not pro- vided with any kind of armature, is nevertheless supplied with a group of well developed retractor muscles which are evidently analogous at least to the single retractor muscle of the Trypanorhyncha. The bulb is not only provided with a musculature arranged so as to diminish on contraction the volume of the organ, but is also lined with an epithelium-like layer comparable to that of the members of the latter group. But since the bulb extends to the point of exit of the proboscis, there is no part corresponding strictly to the proboscis -sheath of Tetrarhynchus altho the stump would at first sight seem to be such. Fur- thermore, the cells forming the large mass behind the bulbs in Haplobothrium which are here interpreted as ganghonic cells, bear not a little resemblance to those described by Braun (1896:1294) after Pintner (1880), Lang (1881) and Niemiec (1888) as associated with the bulbs of Tetrarhynchus longicolUs (v. Ben.) { = Dibothriorhynchus ruficollis Monticelli) and considered by somx to be ganglionic cells and by others myoblasts. The distribution of the large nerve trunks arising from the nerve commissure is also somewhat suggestive of con- ditions in a few of the tetrarhynchids (cf. Braun 1896:1293). While the writer is not prepared to go further into this comparison he would like to emphasize the significance of the layers composing the walls of the bulbs in H. globuliforme in connection with the possible origin of these most aberrant structures. In discussing the homologies of the proboscides cf the Trypanorhyncha Benham (1901) said: "It appears more probable (Pint- ner) that each proboscis has been developed by the deepening and modification of an ' accessory sucker' of some Tetraphyllidean as its relation to the bothridia and its mode of development closely agrees with these structures. Func- tionally too it is a perfection of the armature plus the accessory sucker of three forms [Acanthocephala, Nemertini, and Taenioidea]; whilst there is no doubt that the 'phyUidea' of the orders are identical. " The fact that here the walls of the bulb, since they are composed of an outer layer of longitudinal muscles, a middle layer of circular fibres and an inner cuticular layer are not only comparable but directly continuous with the cuticula and cuticular mus- cles of the body wall and in the reverse order would seem to lend support to 52 ILLINOIS BIOLOGICAL MONOGRAPHS [340 Pintner's view. Simple invagination of the external layers of the body wall in development would account for these structures, while the proboscis with its retractor muscles might well be formed by the modification of the external lay- ers of an "accessory sucker." 341] PSEUDOPHYLLIDEA FROM FISHES— COOPER S3 CYATHOCEPHALINAE Liihe 1899, e.p. Scolex unarmed, not longer than broad, with two surficial sucking grooves, more or less fused with one another, or a single terminal one having a sucker- like structure. External segmentation little expressed or absent. Genital organs in each segment simple. Genital openings surficial, median. Vagina and uterus open into a common vestibule — in young proglottides near one another — lying behind the male opening and similar to the genital atrium of other cestodes, which may be surrounded by a sphincter-Uke musculature. The genital openings of the different segments do not open on the same surface, but alternate irregularly from one surface to the other. Uterus a coiled canal without uterus-sac. Sexually mature in the intestines of fishes. Type genus: Cyathocephalus Kessler. The above is Liihe's (1910:22) diagnosis modified to read "may be sur- rounded, etc." instead of "is surrounded, etc." in connection with the genital sphincter, since there is no such structure in the species described below. CYATHOCEPH.\LUS Kessler 1868 Taenia (part.) Pallas 1781 Taenia (part.) Batsch 1786 Echinorhynchus (part.) Zeder 1803 Cephalocotyleum Diesing 1850 Cyathocephalus Kessler 1868 Cyathocephalus Grimm 1871 Monobothrium Grimm 1871 Acrobothrium Olsson 1872 Cyathocephalus Zschokke 1884 Cyathocephalus Loennberg 1889 Cyathocephalus Kraemer 1892 Cyathocephalus Olsson 1893 Cyathocephalus Luhe 1889 Cyathocephalus Braun 1900 Cyathocephalus Luhe 1900 Cyathocephalus Liihe 1910 Scolex a single, undivided, terminal, sucking organ, which in its form and structure no longer shows an origin from two fused surficial bothria. External segmentation only slightly indicated. Sphincter surrounding the female genital cloaca apparently little developed. Occurrence: In Teleosts. Type Species: C truncatus (Pallas, 1781). CYATHOCEPHALUS AMERICANUS Cooper 1917 [Figs. 11,82,93,99, 104] ? 1898 Cyathocephalus truncatus Linton 1898:428 1917 Cyathocephalus americanus Cooper 1917 : 35 Specific diagnosis: With the characters of the genus. Small cestodes, up to a length of at least Umm. with a maximum breadth of 1.2mm. Scolex 54 ILLINOIS BIOLOGICAL MONOGRAPHS 342] funnel-shaped, 0.3 to 0.6nim. long and 0.5 to 0.9 broad, with revolute edges. Neck 1.0 to 1.8mm. in length. Segments twice as broad as long, terminal one rounded. Cuticula 5 to 6)u in thickness, with neither hooks nor spines; subcuticula 25 to 50m. Ten to twenty sets of genitalia, beginning 1.5 to 2.0mm. from the anterior end. Strong tendency for the reproductive apertures to lie all on one surface of the strobila. Vagina opens behind the uterus. Neither papillae nor sphincters around the genital openings. Testes in two lateral fields in the medulla of the anterior portion of the proglottis, 60 to 70/li in diameter. Coiled vas deferens anterodorsal to cirrus- sac; no seminal vesicle before entering cirrus-sac nor connective tissue sack surrounding the whole duct. Protruded cirrus 0.2mm. in length by 0.12 in diameter at base. Cirrus-sac ovoid in shape 0.20 to 0.23mm. in length by 0.17 in diameter; no retractors connecting it with the dorsal body- wall; large mass of glandular pigmented cells surrounding it dorsally and laterally. Vagina 12 to 15ju in diameter; no sheath near its opening; receptaculum seminis 50 to 75m. Spermiduct very short and narrow, 25 and 8m respectively. Ovary tubulolobular, fan-shaped; wings extending dorsally and laterally around the ventral genital ducts; isthmus prominent, 0.18 by 0.10mm.; ova in same 13 to 15m in diameter. Oocapt 25m in diameter. ViteUine follicles continuous from proglottis to proglottis, forming a layer 90m thick in the cortical paren- chyma, 20 to 35 in transections. Shell-gland dorsal. Uterine rosette not surrounded by a muscular sac, but the organ is enveloped proximally by numerous glandular cells. Eggs, 40 by 30m. Habitat: In stomach, pyloric ceca and intestine of the host. HOST LOCALITY COLLECTOR AUTHORITY {,7)Coregonus dupeijormis Outer Id., L. Sup>erior J. W. Milner Linton 1898 : 429 »» )» Off Giant's Tomb Cooper Cooper (the present Id., Georgian paper) Bay, L. Huron » » Charlevoix, Mich. >> 1) Type specimen: No. 165A, in the writer's collection. Co-type: No. 165B, in the collection of the University of Illinois. T>-pe locality: Georgian Bay, Lake Huron, off Giant's Tomb Island. Altho the species described here is closely related to C. truncattis of Europe, it presents' so many differences from that species, even barring some probable errors by Kraemer (1892), that it is considered to be new. Probably the same form was reported by Linton (1898:428). 343] PSEUDOPHYLLIDEA FROM FISHES— COOPER s:> As shown in the appended table where the largest specunens at hand are dealt with, this species is considerably smaller than the European species which ranges from 6 to 40mm. in length by 1 .5 to 4 in width. Linton gave these measurements as 7 and 1.2mm. The general shape of the body, however, is the same, as are the proportions of the scolex and proglottides. The border of the infundibuliform scolex (Fig. 11) is thickened and almost constantly rolled backward slightly as in the figures given by Zschokke (1884a, Fig. 9) and Kraemer (1892, Fig. 5). The funnel is about 0.22mm. in depth, and is usually filled with a plug of mucous membrane from the host's alimentary tract. The posterior limits of the scolex are difficult to define since the organ gradually narrows down and then as gradually enlarges again to form the neck. The latter is considered to include that portion of the anterior end of the worm between the narrowest region behind the scolex and the first vitelline follicles which are situated some dis- tance ahead of the first cirrus-sac. The maximum breadth of the strobila is at the posterior end of either the first third or one-half. The segments are as described by various writers for C. truncatus about twice as broad as long, the last one, however, being rounded posteriorly and provided with a notch in the middle which accommodates the exit of the excretory vesicle. They are, furthermore, closely united, as pointed out by Linton (1898:429) when he said "The bodies of these specimens appear to be unsegmented, or, at least, with only very faint indication of division into segments." As a matter of fact numerous transverse wrinkles present in most specimens make it almost impossible without the external evidences of the inner genitaUa to distinguish the limits of the proglottides. And in this respect they agree with C. truncatus^ since Zschokke (1884:38) said concerning the segments: "lis sont solidement fixes les uns aux autres, leurs limites sont difficilement visibles. " The follow- ing table gives the measurements of four of the largest specimens studied: Length 10mm. 9mm. 11mm. 7.5mm. Maximum breadth 1.01 0.92 1.11 1.05 Length of neck 1.48 1.00 1.48 1.8 Breadth scolex, tip 0.55 0.53 0.74 0.64 " , base 0.37 0.42 0.55 0.^0 Length of scolex 0.42 0.33 0.61 0.50 Number of sets of genitalia 13 12 13 10 First cirrus from ant. end 1.85 1.66 2.25 2.01 Remarks Toto Toto Toto Sectioned The cuticula is Sfi in thickness over the scolex as well as on the segments, and is divided into two layers, the outer of which is about one-half as thick as the inner and more or less irregular in structure. However, no such chitinous hooks as described by Kraemer (1892 :10) for the cuticula of the lateral borders were seen, but the whole tissue is freely pierced with numerous foramina secundaria of the excretory system, which in C. truncatus Kraemer considered 56 ILLINOIS BIOLOGICAL MONOGRAPHS [344 to be the points of entrance of nutriment. The thickness of the cuticula, according to the same author, is 19^, an outer irregular layer being S^x and showing a sort of ecdysis ("Hautungsprocess"). This, however, may be simply the separation of the outer layer of the cuticula from the inner which often appears in sections, since he said, "Diese Auffassung wird dadurch erhartet, dass sich an einigen Stellen dieser Belag nicht findet, dafiir eine junge homogene Cuticula, " — the latter being then the inner homogeneous layer. At any rate, it is quite evident that the cuticula of C. triincatus is a much thicker tissue than that of the form described here — and no one else than Kraemer seems to have described it. The subcuticula is comparable to that of C. truncatus in that it varies in thickness from 25 to 40/i. It is composed of considerably elongated columnar cells whose nuclei, 5;u in diameter, are as thick as the cells themselves. Scat- tered spaces in the loose parenchyma, which evidently accommodated cal- careous bodies before they were dissolved in the fixing fluid, were found to be eUipsoidal to almost spherical in shape and to vary from 13 to 25/i in length by 7 to 18 in width. Linton stated that the calcareous bodies of C. truncatus are 10 to 20/u long, Zschokke that they are 8 to lO^i and Kraemer that their size is 30 by 18/i. In general the musculature is as described by Kraemer, but all the groups are comparatively weakly developed (Fig. 82). The longitudinal layer, for instance, is only 20/^ in thickness in the median line posteriorly and about 60/x in the neck region (76^ in C. truncatus) where the dorsoventral and transverse fibres are also much stronger than elsewhere. In the anterior part of the neck, particularly immediately behind the scolex, the fibres of the two latter series are much stronger, altho less numerous than farther back. Just ahead of the posterior end of the funnel they become arranged in an arcuate manner longi- tudinally as well as transversely. Then from there on to the tip of the scolex they gradually become more nmnerous as they concentrate around the funnel of the organ, of which they obviously act as constrictors. Antagonizing these are numerous weaker radial fibres, arranged as in C. catenatus Riggenbach { = Diplocotyle rudolphii Mont.) where they were considered by Riggenbach (1898:639) to be derived from the longitudinal muscles with which they are continuous at the base of the scolex. Altho they mingle freely among the latter, they are still quite separate from them. Thus the writer is inclined to the same view regarding their homologies in C. americanus, since it seems clear that the dorsoventral and transverse fibres, which might otherwise be con- sidered to give rise to them, become modified to form, the circular muscles of the scolex. As a matter of fact only a very few of the longitudinal muscles of the neck pass for a short distance beyond the bottom of the funnel; most of them are inserted in the latter, thus functioning with the radial fibres in enlarging the organ of adhesion. According to Riggenbach these radial muscles are ap- parently absent from C. truncatus. They were not described by Kraemer; but the enlargement of the funnel was considered to be accompUshed by the con- traction of the dorsoventral fibres (cf. his Fig. 1). The outermost layer of 345] PSEUDOPHYLLIDEA FROM FISHES— COOPER 57 circular and longitudinal muscles in the scolex, which are merely extensions of the cuticular muscles of the neck region, are not nearly so strongly developed as in C. truncatus. There is, however, in the neck region, particularly in its anterior portion, a series of outer longitudinal muscles which, altho situated in transections among the outer clear ends of the subcuticular cells and very close to the longitudinal cuticular fibres, are nevertheless quite distinct from the latter. At the base of the scolex they pass inwardly between the cells of the subcuticula and continue farther towards the anterior border of the funnel than do the inner or main longitudinal fibres. Posteriorly they diminish con- siderably in number but may readily be seen in the mature proglottides. The nervous system is arranged in general as in C. truncatus; but the longitudinal trunks are only 26/i thick by 13 wide (0.345mm. according to Kraemer). In the neck they are scarcely enlarged to form ganglia, such as shown in Kraemer's Fig. 5, but each is divided into two distinct dorsoventral halves which gradually diverge as they pass on into the scolex to form four large nerves. There is no single transverse commissure connecting the main trunks behind the funnel of the scolex but instead a number of fine cross-connections which are often difiicult to make out satisfactorily. As regards the excretory system there is an inconstant number of longi- tudinal vessels in transection, evidently more than the six of C. truncatus, which do not occupy definite positions but anastomose freely with each other especial- ly in the lateral portions of the medulla. In the scolex these vessels are smaller and the anastomoses are much more numerous, while posteriorly at least two pass into a quite irregularly shaped terminal vesicle, which, however, in the light of Wolf's (1906) findings cannot be considered to be a true terminal excretory vesicle. As above stated, foramina secundaria are quite numerous in the cuticula. The reproductive organs appear quite close behind the neck, the vitelline foUicles being situated from 1.3 to 2.3mm. from the anterior border of the scolex, and the first cirrus-sacs from 1.6 to 2.2mm. From 10 to 20 sets of genitalia were observed for this species. These follow each other closely and are not separated by any septa or other boundaries, the vitelUne follicles being, in fact, strictly continuous from proglottis to proglottis. The openings of the cirrus-sacs vary from 0.45 to 0.75mm. apart, but as pointed out by Kraemer, these measurements are of little diagnostic value on account of the different states of contraction. As in C. truncatus the reproductive openings are all on one surface of the proglottis but alternate as a unit irregularly from one surface to the other. There is, however, a strong tendency for them to lie all on the one face of the strobila. This alternation also involves the ovary, the isthmus of which is arbitrarily considered in the cestode to be ventral. It usually Hes on the same surface as the reproductive openings, so that when the latter passes to the opposite surface it moves accordingly. This alternation of the openings has, of course, been known ever since Pallas described Taenia truncate in 1781, but, so far as the writer is aware, no one has dealt with the relations between the openings and the ovary noted here. Concerning this matter Kraemer 58 ILLINOIS BIOLOGICAL MONOGR-iPHS [346 said only: "Das Verhalten, dass die Geschlechtsorgane altemirend dorsal und ventral nach aussen miinden, erinnert in gewisser Beziehung, an die altemier- ende marginalen Geschlechtsofifnungen verschiedener Fisch- und Vogeltaenien und wurde bereits von den ersten Beobachter, Pallas und Batsch erkannt, d.h., sie hatten auf beiden Flachen die fortlaufende Reihe der 'Punkte' wahrge- nommen, ohne sie indessen als Ausmiindungen der Sexualorgane zu deuten. Die neueren Beobachter haben sammtlich dieses oben beschriebene Verhalten iibersehen, und geben die Geschlechtsoffnungen als ventral gelegen an. " But whatever is the stimulus which, during the very early stages of development of the sets of genitalia from their rudiments, causes the reversal of the whole proglottis, it would seem to be such at times as to fail to bring about the turning over of all parts of the rudiment. As shown in figure 104, which is a diagram of a sagittal series of seven proglottides including the terminal one, the cirrus and female genital cloaca of number three from the top have gone to the oppo- site surface while the ovarian isthmus, represented by the solid black disc in each segment, has remained on the same surface as those in segments 1, 2 and 4 in the immediate neighborhood. Here the stimulus which brought about the unisurficiality of the latter may have influenced the ovarian portion of the common rudiment of number three and caused it to lag behind, while the more peripheral rudiments of the cirrus, vagina and distal portions of the uterus were freer to move. This arrangement of the parts in the aberrant segment in question naturally causes considerable departures in the courses of the repro- ductive ducts from the normal. The genital openings vary from 75 to 115^ apart, but again as pointed out by Kraemer these data are of very little specific value. The vagina and uterus open into a common genital sinus or cloaca, but unlike conditions in the European species the vagina opens constantly behind the uterus and slightly to one side and not ahead of it. Furthermore, neither papillae nor sphincter muscles are present around either or both genital openings in this species. The female genital cloaca, usually situated at the bottom of a depression and often on a low papilla, ranges from 30 to 60)u in depth. In frontal sections it is seen to be in the form of a transverse slit about 60^t in length, into the ends of which the vagina and uterus empty; that is, the vagina opens diagonally behind the uterus and usually to the right of it. It is lined by a direct continuation of the cuticula from the surface of the segment. The general habit of the reproduc- tive organs is shown in figure 93, which is from a frontal section of a mature proglottis. The majority of the testes are situated in the medullary parenchyma in two fields lateral to the cirrus-sac, or more strictly speaking, in the lateral portions of the region between the cirrus-sac and the ovary of the proglottis ahead, since they usually extend forward to the latter and backward to the anterior ends of the wings of the ovary of the segment to which they belong. While their shape is usaully spherical or somewhat flattened anteroposteriorly accord- ing to the condition of contraction of the segment, their maximum diameter is about 70^. The coils of the vas deferens, altogether about 0.30mm. in dia- 3471 PSEUDOPHYLLIDEA FROM FISHES— COOPER 59 meter, are accommodated in the somewhat confined space dorsal and anterior to the cirrus-sac, extending to the ovary ahead (Fig. 93). Whereas Kraemer gave the diameter of the duct as 0.133mm. or about eight times as large as just before it enters the cirrus-sac, it is only 45^ at the most in this species. Fur- thermore, it is not enlarged to form a seminal vesicle close to the cirrus-sac, as shown in Kraemer's figures 6 and 13, but gradually diminishes in size until as it pierces the wall of the latter its diameter is only 10^. Nor is the whole vas deferens enclosed in a connective tissue sac, such as described by Kraemer. Within the pouch it enlarges considerably to form a thin-walled inner seminal vesicle, situated for the most part near the proximal end of the former but often lying alongside the cirrus proper. This portion of the duct may attain a diameter of 30/x even when empty. Then follows the cirrus proper which is sharply separated from the seminal vesicle ; as a matter of fact it actually pro- trudes backward into the latter with a diameter of 10^ and for a distance of from 15 to 25/x. The extruded cirrus has a maximum length of 200/i, diameter at the base of 120^1, and at the tip of about 40^. The thick cuticula covering the organ is decidedly roughened or irregularly "cleft," especially towards the tip, but not provided with spines of any kind. Incidentally, the protrusion of the cirrus on account of its size, results in the eversion of almost the whole of the contents of the sac. The length of the cirrus within the sac is at least 185^, — it is usually bent once in its proximal portion— while its diameter varies considerably. The layer of parenchymatous and myoblastic nuclei surround- ing the cirrus within the sac is about 10^ in thickness as compared with 5/i in C truncakis. In sections of the extended cirrus most of these nuclei appear in the tip of the organ surrounding a good deal of the cuticula which still remains invaginated; but they are in all probability myoblastic as are others farther back along the course of the retractor fibres. In frontal sections the cirrus-sac is circular in outline (Fig. 93), its maximum diameter being 175m, while in transverse and longitudinal sections it is oval in shape and the diameter (length of the organ) ranges from 200 to 230^. The smaller end is directed ventrally. Its waU is comparatively thin, ill defined, and composed of a som.ewhat loose network of muscular fibres running irregularly obhquely in all directions, so that sections cut in any plane show them almost circularly arranged. Owing to this fact and to the further fact that its innermost fibres are not easily dif- ferentiated from the retractors of the cirrus proper which bulk largely in the contents of the sac, the wall is fairly difficult to locate with emission of the cir- lus. The sac is furthermore not provided with any retractors connecting it with the dorsal body-wall as described by Kraemer for C. truncatiis. Formmg a sort of gland closely applied to that part of the cirrus-sac within the medulla there is to be seen, even in toto preparations, a comparatively large mass of large darkly pigmented polygonal cells (Fig. 93). In frontal sections they Ue on each side of the sac but do not extend much beyond its anterior and poster- ior edges, the whole structure being thus shaped somewhat like a saddle. Each cell is elongate in shape provided with a well-defined wall, prominent tho not especially large nucleus, and very granular and highly pigmented cytoplasm. 60 ILLINOIS BIOLOGICAL MONOGRAPHS [348 the color of the pigment being dark bro-wn. Ahho they are very closely ar- ranged around the wall of the cirrus-pouch and most of them are quite pointed towards the same, their function is pretty much a matter of conjecture; unless perhaps they are the much modified myoblasts of the muscles of the walls of the pouch. This is suggested by the intimate relations of the inner at- tenuated ends of some of them with the latter. No such cells have been de- scribed for the European species, so far as the WTiter is aware. It would seem, however, that certain "radiar gesteUten, kolbenformigen Driisen," merely mentioned and figured by Linstow (1904:308, Fig. 26) as surrounding the cirrus-sac of Bothrimonus pachycephaliis Linstow, are similar to these peculiar cells. But in the latter species they are evidently much less extensive than in C. americanus. Similar glandular cells were also described by Schneider (1902: 76) for Bothrimonus nylandicus Schneider. From its opening which has been dealt with above the vagina proceeds dorsally almost at right angles to the surface of the proglottis, and then within the medulla turns backward with a few coils to expand into a comparatively enormous receptaculum seminis which, on account of its size, can scarcely be distinguished from one of the coils of the uterus. At the turn in its course the duct has a diameter of about 15^ and is hned with a continuation of the cuticula of the female genital cloaca, 5/i in thickness, and surrounded by a layer of circular muscles. As it passes above the ovarian isthmus its cuticular lining gradually diminishes in thickness, so that the senrdnal receptacle is provided with a very thin layer only. While the latter may have a diameter of 75m slight- ly behind the isthmus of the ovary, it narrows dowTi very abruptly before joining the oviduct to a very small spermiduct, 8ju in diameter and about 25/i in length. In distinct contrast with C. truncatus there is no "connective tissue and muscular sac " surrounding the beginning of the vagina, as described by Kraemer, but only the usual mass of nuclei, most of which are subcuticular in their nature. The ovary (Figs. 82, 93) is a tubulolobular organ, the lunbs of which radiate from a ventral isthmus laterally as far as the nerve strands, anteriorly as far as the cirrus-sac, and dorsally thruout the whole of the medulla, thus surrounding the central connections of the genital ducts and the coils of the uterus (Fig. 93). The wings, in whose irregularly shaped tubules young ova in various stages of development are to be seen, connect with the rounded isthmus by narrow portions quite as described and figured by Kraemer, altho he evidently erroneously called the isthmus the "ootyp." The latter in this species has a width of 0.18mm. by a length of 0.10 as compared with the similar measurements of 0.19 and 0.07mm. in the case of C. truncatus. Ova from the isthmus measured from 13 to 15/i in diameter, their nuclei 7 to 8/i and their nucleoH 4^, those of the latter species being 9 to 12/Lt according to Grimm (1871) and IS/i according to Kraemer who gave the diameter of their nuclei as 9/i. The oviduct begins with a rather short oocapt (Fig. 99), 25ij. in dia- meter, and proceeds for only a comparatively short distance, with a diameter of from 15 to 20/i, before being joined by the spermiduct. A Httle farther dorsally it is met by the vitelUne duct which comes from the ventral portion of 349] PSEUDOPHYLLIDEA FROM FISHES— COOPER 61 the medulla just ahead of the isthmus where it is formed by the union of a right and left duct as in C. truncatus. Thruout its dorsoventral course the vitelline duct is expanded to form a vitelline reservoir which may reach a diameter of 40)U. Immediately outside of the longitudinal muscles the vitelline follicles form a compact layer from 70 to 90ju in thickness (152/x in C. truncatus), con- tinuous from proglottis to proglottis and broken only immediately aroimd the reproductive openings. They range in diameter from 30 to 85m, while their number in transverse sections varies from 20 to 35, 45 being given by Kraemer. From its point of origin to a short distance beyond the entrance of the vitelline duct, the oviduct is lined •wnth epitheUal cells showing prominent nuclei but indistinct boundaries, the whole being thus of the nature of a syncitium. But soon this epitheUum becomes modified in that, as the duct continues with a few coils to the opposite side of the proglottis, its cytoplasmic portion gets quite thin, while the nuclei remain more nearly the same size relatively speaking. Then as it further enlarges dorsally the oviduct is surrounded by an incon- spicuous shell-gland. However, no shell-gland such as described by Kjaemer was found in this species. Beyond the ootype the duct, in reality the beginning of the uterus, is enveloped for a considerable distance by numerous unicellular glands which at first sight appear to constitute a second and voluminous shell- gland. This mass of glandular tissue is so extensive in fact, that it occupies in frontal sections about one-half of the posterior half of the uterine rosette (Fig. 93). The individual cells, of which it is composed, are comparatively short, stout and well defined, their nuclei being large and the nucleoplasm clear like the cytoplasm. Most of the coils of this tubular uterus, which may attain a diameter of 0.10mm. or more when filled with eggs (0.038mm. in C. truncatus), are situated just behind the cirrus-sac. Before reaching the opening, the position of which has been stated above, the tube narrows down quickly. Thruout its course it is lined with a much attenuated epithelium, the nuclei of which, however, stand out prominently towards the lumen. In this species there is no muscular sac surrounding the uterus, as described and figured by Kraemer. The largest eggs in the uterus not in a collapsed state were found to be ellipsoidal in shape and 40 by 30/1 in size. Linton gave then- size when pre- served in acetic acid as 50 by 32/i; while the measurements for C. truncatus have been given as 95 by 76^ (Kraemer) and 44 to 51 by 2>3> to 36/x (Liihe, 1910). Since most of the eggs seen in the uteri of the sections made were quite young, many of them not having gone thru the first cleavage as yet, the writer is of the opinion that the size of the egg of this species is probably about the same as that given by Luhe for C. truncatus in Europe. Altho evidently no one has as yet studied the early stages in the develop- ment of C. truncatus, Wolf (1906) discovered that the intermediate host is Gammarus piilex and that the transfer to the final hosts is a direct one. As re- gards the Ufe histor>' of C. americanus the writer can only say that he is of the opinion that Pontoporeia hoyi (Stimpson Mss.) may later be found to be the intermediate host at least in Georgian Bay, Lake Huron, where it constitutes practically the only food of Coregoniis clupeiformis. 62 ILLINOIS BIOLOGICAL MONOGRAPHS [350 In the above description it has been shown that this species differs from the well-knowm C. trmicatus of Europe in a great many points, but in none so radically as the following: The absence of chitinous hooks on the cuticula of the lateral borders ; the presence of radial muscles in the walls of the scolex, and of a number of fine nerve commissures connecting the chief nerve strands anteriorly instead of a single one; the vagina opening behind the uterus opening; the absence of papillae and sphincter muscles surrounding the genital openings; no enlargement of the vas deferens to form a seminal vesicle just before enter- ing the cirrus-pouch; no connective tissue sac surrounding the whole of the coiled vas deferens; the absence of dorsal retractor muscles of the cirrus-sac, and the presence of the pecuUar glands closely surrounding the pouch; no "connective tissue and muscular sac" surrounding the beginning of the vagina; the very different central connections of the genital ducts as regards the ovarian isthmus ("ootyp" of Kraemer); and lastly, the absence of any such "shell- gland " as described by the same author. Consequently it has been considered to be specifically different from the European form and given a new name. The material studied consisted of three lots, Nos. 43, 165 and 382A of the writer's colllection from the stomachs and intestines of several specimens of Coregonus clupeiformis (Mitchell) from Lakes Huron and Michigan as Hsted above. BOTHRIMONUS Duvernoy 1842, char, emend. Bothrimonus Duvernoy 1842 Bothrimonus Dujardin 1845 Bothrimonus Diesing 1S50 Cephalocotylea Diesing 1850 Disymphytobothrium Diesing 1854 Diplocotyle Krabbe 1874 Diplocotyle Monticelli 1890 Bothrimonus Monticelli 1892 Diplocotyle Braun 1900 Bothrimonus Braun 1900 Diplocotyle Ltihe 1900 Bothrimonus Liihe 1900 Bothrimonus Schneider 1902 Diplocotyle Linstow 1903 Bothrimonus Linstow 1904 Scolex with two surficial and almost spherical bothria whose forwardly directed apertures may be separate or more or less completely fused to form a single terminal opening, according to the degree of contraction of the ridge separating the two internally, the latter representing the tip of the scolex in other bothriocephaUds. External segmentation completely absent. Female genital cloaca with more or less well developed sphincter. Vitelline follicles in the cortical parenchyma in two lateral fields. Occurence: In species of Acipenser and in teleosts. Type species: Bothrimonus sturionis Duvemov. 351] PSEUDOPHYLLIDEA FROM FISHES— COOPER 63 As pointed out by Schneider (1902a :72) the two genera Bothrimonus and Diplocotyle were separated by Liihe (1900:10) only on the basis of the differ- ences in degree of fusion of the apertures of the bothria at the tip of the scolex. As a matter of fact the remainders of the generic diagnoses are identical. Schneider stated that the material of his B. nylandicus showed that these differences were simply due to differences in degree of contraction and relaxa- tion of the scolex and in particular of its termination which is the ridge separat- ing the two openings of the bothria either externally or internally. With considerable retraction of this ridge or septum the two openings fuse to form one, while with relaxation of the same and contraction of the bothrial walls the apertures are more or less separate, according to the species present. While in none of the few specimens of the species described below were the openings fused, various stages in the formation of a single terminal and almost circular opening from the two otherwise separate openings were observed in some material from Microgadus tomcod which was, however, too young to be determined with certainty specifically. Consequently, it seems just with the present state of our knowledge of these forms to unite the two genera, Bothrimonus and Diplocotyle, and to retain the older name of Duvernoy, as done by Schneider but not recognized by Linstow (1903; 1904:308). BOTHRIMONUS INTERMEDIUS Cooper 1917 [Figs. 6-8, 45, 81, 94] 1917 Bothrimonus intermedins Cooper 1917 : 35 Specific diagnosis: With the characters of the genus. Small cestodes up to 45mm. in length and 1.6 in breadth. Scolex almost spherical, 0.60mm. long, 0.75 wide and 1 .0 thick. Bothria hemispherical, their apertures ordinarily not fused to form a single terminal opening. Strobila uniform in width from a short distance behind the scolex to the posterior end; 0.6mm. in thickness; more convex ventrally than dorsally. Cuticula 5m in thickness. Nerve strands 15 to 20/i in diameter; each divides into two branches sagittally before entering the scolex; transverse com- missure diffuse. Four main excretory trunks in ripe proglottides, six farther forward passing into the scolex; all in the medullary parenchyma. Reproductive organs 1.5mm. from scolex; up to 66 in number. Weak sphincter around the common female cloaca. Vagina opens close behind the uterine pore which is not quite in the median hne. Testes in two lateral fields and two layers between the excretory trunks, continuous from proglottis to proglottis; spherical in shape, 80 to lOOju in diameter. Coils of vas deferens anterodorsal to cirrus-sac, the duct 30/x in diameter. Cirrus-sac oval, 75 by 45^ ; everted cirrus, 60 by 85/i. Vagina lOju in diameter; receptaculum seminis, 40 to 60^; spermiduct, lO/x. Ovary crescentic in shape, wings tubulolobular; isthmus almost spherical, 0.1mm. in diameter. Oocapt ISfi in diameter, oviduct 15 to 20^. Common vitelline duct 120 by 30^. Vitelline follicles spherical, 60// in diameter; in the lateral thirds of the strobila, continuous at the margins of the same and from 64 ILLINOIS BIOLOGIC A L MONOGRA PHS [352 proglottis to proglottis. Shell-gland obscure. Uterus surrounded by glandu- lar cells proximally; 0.25mm. in maximum diameter. Eggs, 36 by 24^ in dimensions. Habitat: In the intestine of Pseudopleuronedes americanus (Walbaum), the winter flounder, from Brandy Cove, St. CroLx River, at St. Andrews, New Brunswick. Type specimen: No. 206.1 in the writer's collection. Co-type: No. 206.2 from the same, deposited in the collection of the Uni- versity of Illinois. Since 1842, when Duvemoy described Bothrimonus sturionis, the type species and the only one reported for America up to date from a specimen of Acipenser oxyrhynchus Mitchill { = A. stiirio L.) collected by M. Lesueur in 1835, the following species have been found in Europe: Diplocotyle olrikii Krabbe (1874), D. rudolphii MonticelH (1890:205), B.fallax Liihe (1900b:257), j5. nylandicus Schneider (1902a:72), D. cohaerens Linstow (1903:291) and B. pachycephalus Lmstow (1904:307). As pointed out by Schneider (1902:77), D. serrata Linstow (1901:288) evidently does not belong to the genus at all. But with none of these could the material studied in connection with the present description be alligned. Altho it bears resemblances in individual points to B. cohaerens and to B. pachycephalus, doubtless owing to the fact that these have been better described than the others, including B. fallax, and closely approaches B. nylandicus, yet it is so different from the latter that it is con- sidered to constitute a new species. The scolex (Figs. 6-8,) is typical in that it is composed of two surficial and almost hemispherical bothria arranged in the usual manner. These are well separated not only posteriorly from the strobila but laterally from each other by distinct grooves as in B. nylatidicus. In all of the specimens studied the apertures of the bothria, usually circular in shape and about 0.1mm. in diame- ter altho in a few cases somewhat elongated dorsoventrally, were distinctly separate. But since, as shown by Schneider, there is great variation in the extent of fusion of the two apertures owing to differences in degree of contrac- tion even in individual species, this separation is not considered to be of speci- fic, let alone generic, value. The compressed lumen of the bothrium has a transverse diameter of 0.3mm.; while the other measurements of the scolex are as given in the table below. The short unsegmented region between the scolex and the first set of genitalia, which has a length of about 1.5mm., may be considered to be a neck. Excepting for the openings of the reproductive organs and the protruded cirri, there are no external indications of segmenta- tion. Internally this is also the case as regards the vitellaria and testes, which are both strictly continuous from proglottis (set of genital organs) to proglot- tis, as in the genus Bothriocephalus (vide infra). The strobila, which is quite uniform in diameter from the region close behind the scolex, is about one-half as thick as broad and slightly more convex ventrally than dorsally, as in B. nylandicus. None of the specimens at hand were complete posteriorly. The 353] PSEUDOPHYLUDEA FROM FISHES—COOPER 65 following table gives measurements of the three largest specimens of the ma- terial studied: Length 45mm. 38mm. 21mm. Length of scolex 0.55 0.59 0.37 Length of bothria 0.64 0.72 0.66 Breadth of scolex 0.74 0.76 0.72 Depth of scolex 0.90 0.94 1.02 Width of strobila just behind scolex 0.87 0.87 0.74 Maximum breadth 1.34 1.34 1.60 Average breadth 1.16 1.16 1.2 Depth at middle 0.55 0.50 0.61 The cuticula is about Sy. in thickness not only over the general surface of the strobila but also in the interior of the bothria. In the latter situation it is divided into two layers comparable to those described by Schneider (1902a: 75) for B. nylandicus: an outer, occupying about three-fifths of the whole thickness and made up of comparatively long comidia or pseudocilia, and an inner, quite darkly staining stratum. Whereas Schneider stated that "Diese Harchen finden sich uberall auf der ganzen Oberflache des Cestoden mit alleiniger Ausnahme der beiden Hohlraume in den Saugnapfen und der Rinne, welche den Scolex vom Rumpfe scheidet, " the writer found that these were the very places the two chief layers were best seen. The musculature is quite similar to that of B. nylandicus as described by Schneider. All of the series are about equally, but none strongly, developed and each consists of isolated fibres. The arrangement of the fibres in the scolex is quite like that of Clestobothrium crasslceps, there being, however, no sphincters controlling the openings of the bothria. The main longitudinal nerves are situated in the median frontal plane and about two-ninths of the transverse diameter of the strobila from the margins, posteriorly as well as in the neck region. In transverse sections each strand varies considerably in size and shape, but it is constantly considerably com- pressed and has a transverse diameter of from 15 to 20/i. Anteriorly the system differs greatly from that of B. nylandicus. In the latter, according to Schnei- der, the chief strands bend outwardly at enlargements in the region between the scolex and body; and from each of these nerves are given off to the neighboring bothria and one main branch towards the tip of the region to unite with its fellow of the opposite side, thus forming a commissure which is bowed forward. In this species each main trunk divides from 0.25 to 0.40mm. behind the poster- ior borders of the bothria into two branches of equal size which continue for- ward in a strictly sagittal plane as they gradually enlarge. At about the mid- dle of the bothria each of these four trunks gives off large branches to the lateral walls of the former, and then, while approaching the median line and partly fusing with its fellow of the opposite surface, sends off several small branches to those on the other side. The commissure is, therefore, not single but composed of a number of transverse connectives of varying size. The 66 ILLINOIS BIOLOGICAL MONOGRAPHS [354 transverse ridge between the bothria, which represents the tip of the scolex, is also supplied with a number of small nerves from this irregular commissure. In ripe proglottides there are four main longitudinal excretory vessels situated roughly in the median frontal plane, two at the extreme margins of the medulla and two just within the nerve strands. Farther forward these divide into three on each side. The middle one of each lateral trio then divides dorsoventrally into two, while the innermost pair gradually diminishes in size and are soon lost. This leaves three on each side, arranged as a triangle with the base towards the median line and the apex outward. They pass into the scolex and anastomose to form an irregular plexus. But this arrangement of the main vessels is attended with a good deal of irregularity; nor is it the same on both sides of the median Hne. For B. nylandicus Schneider described only two main longitudinal trunks "which divide anteriorly into several canals and form numerous coils, especially in the suckers." The excretory system of B. fallax according to Liihe (1900b :257) is Uke that described here in that there is a triangle of vessels on each side anastomosing with each other and with the nearest ones of the opposite side; but in adition it shows two other vessels which "... verlaufen im Gegensatz zu den diinnwandigen Gefassen des Plexus im Inneren der Markschicht, in der frontalen Medianebene, und zwar der erne nach innen, der andere nach aussen vom Langsnerv^enstamm. Letzter- er erinnert seiner Lage nach an die Verhaltnisse bei den Dibothriocephalinen, insofem als die Mehrzahl der Hodenblaschen nach aussen von ihm liegt. " It will also be seen that the arrangement of the excretory vessels in this species is quite different from that described by Linstow (1904:308) for B. pachycepha- lus Linstow, in which species there are fourteen main vessels situated in the cortical parenchyma among the longitudinal muscles. None of the specimens were complete posteriorly so that the disposition of the system in the true posterior end was not determined. The reproductive organs appear about 1.5mm. behind the scolex almost completely developed. Their openings are in the median line and, unlike B. sturionis Duvemoy, all on the ventral surface, that is, on the same surface towards which the ovarian isthmus is situated (cf. B. fallax Liihe, 1900:10 and Cyathocephalus amerkanus, p. 57). Furthermore, while the male and female openings are from 0.09 to 0.22mm. apart, the sets of genitaUa up to 66 in num- be, are 0.55 to 0.65mm. apart in the longitudinal direction, which distances are, however, of no great specific value owing to the different degrees of con- traction and relaxation of the strobila. The female genital cloaca is an irregu- larly circular opening into which the vagina opens constantly close behind the uterus, as in B. nylandicus, but in the median line, the uterine orifice being in this case the one which is not exactly in line with that of the vagina and the cirrus but alternates irregularly from side to side. There is a weakly developed sphincter surrounding the common female cloaca. It seems, however, to be at least partly confined to the vagmal opening rather than to that of the uterus. As in B. nylandiais, B. pachycephalus and B. cohaerens the testes are situated in the medullary region and in two narrow lateral fields continuous 355] PSEUDOPHYLLIDEA FROM FISHES— COOPER 67 from proglottis to proglottis. As a matter of fact, they are confined to the areas between the two pairs of the four main longitudinal excretory trunks mentioned above. They are usually almost spherical in shape with maximum diameters of 80 to 100^- Transverse and sagittal sections show that, owing to the large size of the median reproductive organs, especially the large uterus, and their consequent inability to expand laterally, they are arranged in two pseudostrata which occupy the whole of the dorsoventral diameter of the medul- la of the regions in question. These two tiers are, however, not nearly as extensive as in B. pachycephdus Linstow (1904:308, Fig. 26). The vas deferens is in the form of a narrow mass of coils, situated immediately anterodorsal to the cirrus-sac or sUghtly to one side, depending on the amoimt of distension and consequent approximation of the uterus of the same proglottis to that of the proglottis ahead. It also extends to the dorsal waU of the medulla; and its diameter is about 30m- Just within the cirrus-sac the vas deferens is sur- rounded for a short distance by radiating gland-like cells, reminding one of those outside of the pouch in C. americanus. But there are no such cells out- side of the cirrus-sac as described for B. nylandicus by Schneider. Then it gradually diminishes from a diameter of 35/i in the ejaculatory region, which immediately foUows, or perhaps includes the glandular region, to about 20m at the middle of the sac. From this point it enlarges quickly and takes on the cuticula and a series of circular muscular fibres to form the cirrus proper which in the distal portion of the pouch may attain a diameter of 50^. The extended cirrus has a maximum length of about 60m and diameter of 85m. The cirrus-sac is oval in shape, the smaller end being outward and the major axis at right angles to the surface. Its depth is 0.25mm. while its diameter is 0.17mm. As in C. americanus its muscular walls are only weakly developed and hence not very distinctly separated from the parenchymatous tissue within and with- out. Apart from the duct the contents of the pouch consists of numerous parenchymatous cells and retractor muscles, the whole forming a quite compact structure. Just within the medulla the vagina turns backward and continues ventrally and posteriorly with a few coils toward the ovarian isthmus. Whereas its diameter is 30m near its opening, half way along its course this is reduced to 10m and enlarged again to 40 to 60m to form the seminal receptacle. Close behind and somewhat dorsal to the isthmus it again becomes sharply restricted to 10m to form the spermiduct. Its whole course is quite as described for B. nylandicus; but in the latter there is evidently no enlargement to form a seminal receptacle or it was overlooked by Schneider, as indicated in his statement: "Sie passiert gleichfaUs auf dem kiirzesten Wege die Subcuticularschicht imd die Muskelschichten, biegt dann in stumpfem Winkel nach hinten um und zieht, immer enger werdend, gegen den Ovidukt hin. In der Nahe des Eileiters wird sie so eng imd diinnwandig, dass die Einmiindungsstelle nicht genau festgestellt werden konnte." The ovary is like that of B. nylandicus in that it is crescentic in shape, the tubulolobular wings extending to the dorsal musculature and surrounding the uterine coils. It is, furthermore, comparable 68 ILLINOIS BIOLOGICAL MONOGRAPHS [356 to C. americanus in that these wings also pass forward from the isthmus — but only halfway along the sides of the uterus — and that the median region of the latter is spherical and somewhat larger than the lateral portions. From the anterodorsal aspect of this enlargement, which has a diameter of about 0.1mm., the oviduct arises as described and figured for B. nylandicus. The diameter of the oocapt is about 25/x, while that of the oviduct beyond its point of union with the spermiduct is from 15 to 20^. The common vitelUne duct, formed by the union close within the ventral musculature of a right and left duct, has a diameter of 30jLt when filled with the yolk cells. The whole of the common duct, 0.12mm. in length, acts as a vitelline reservoir, while the right and left ducts usually contain a good deal of yelk close to their junction. As in B. nylandicus the vitelline follicles are arranged in two lateral fields in the cortical parenchyma, which are not only so restricted as to leave %\'ide median areas free of them dorsally and ventrally but are continuous at the margins of the strobila as well as from proglottis to proglottis. Like the testes they are spheri- cal in shape, closely arranged, and have maximum diameters of 60^. The shell-gland, located just beyond the point of union of the common vitelline duct with the oviduct, is so weakly developed that it is all but absent. The opening of the common vitelline duct into the oviduct was not found to be "from the right side" as in B. nylandicus but irregularly from either side. Nor was there seen any distinct enlargem.ent of the oviduct in the region of the ootype. The first portion of the uterus is very thin-walled, and, especially when free of eggs, quite distinct from the distal portion which attains a diameter of 0.25 mm. The whole duct is so voluminous when filled \vith eggs that it occupies ahnost the whole of the mxedullary region of the proglottis and hence more than one-third of the transverse diameter and closely approximates that of the proglottides ahead and behind, thus crowding the other organs ahnost to the point of obliteration — and this in spite of the fact that its coils, mostly ar- ranged in the sagittal direction, are very close together. The distal end of the duct gradually narrows dowoi in passing ventrally to a diameter of from 35 to 45^i as it pierces the ventral musculature to open ahead of the vagina as above mentioned. No special enlargement of the tube just before its opening, such as was described for B. nylandicus is present in this form; but a considerable length of the proximal portion of the duct is surrounded by glandular cells quite similar to those of C. americanus (cf. p. 61). The maximum dimensions of the eggs are 36 by 24/x as compared to 40 by 25/1 in B. nylandicus. As the above description indicates, this form comes closest to B. nylandicus Schneider, but it diflfers from that species in the followng important points: It is considerably larger; the cuticula lining the bothria is the same as that covering the general surface cf the strobila; the number and arrangement of the excretory vessels are quite different; the structure of the nervous system especially anteriorly is radically different; there are more than twice as many sets of genitalia; there are no gland-like cells just outside of the cirrus-sac; the vagina is expanded proximally into an elongated seminal vesicle; the open- 357] PSEUDOPHYLLIDEA FROM FISHES— COOPER 69 ing of the common vitelline duct into the oviduct is not from the right side only but from either side; the opening of the uterus, and not that of the vagina, is not strictly median but alternating irregularly from side to side, while there is no enlargement of the uterus just before its opening; and finally, but of least importance, there is no fusion of the bothrial apertures. Consequently it seems fitting to consider this form a new species. The material studied consisted of two somewhat fragmentary lots, Nos. 205 and 206 of the writer's collection, from Pseiidopleuronectes americanus (Wal- baum), the winter flounder. 70 ILLINOIS BIOLOGICAL MONOGRAPHS [358 MARSIPOMETRINAE Cooper 1917 Scolex with two typical and fairly deep bothria and a terminal disc. Exter- nal segmentation very distinct and regular. Opening of cirrus and vagina marginal, irregularly alternating; uterus-opening surficial, ventral, at the same level with the genital cloaca or very slightly behind it. Only one set of gen- italia in each proglottis. Testes in medulla between the nerve strands. Mus- cular vesicula seminalis outside of the cirrus-sac absent. Receptaculum seminis large, sharply separated from the spermiduct. Ovary not exactly in the median line but slightly approaching the margin bearing the genital cloaca, ventral, as is the shell-gland. Uterus in the form of a sac developed by the en- largement inwardly of that portion of the duct passing thru the cortical paren- chyma. Eggs without opercula. Type genus: Marsipometra Cooper. As regards the general form of the scolex and the facts that the genital cloaca is marginal and that a vesicula seminalis is absent, Marsipometra comes closest to the Triaenophorinae ; otherwise, however, it is related to other subfamilies. External segmentation is distinct and very regular, a neck being present as in Diphyllobothrium and Bothridium of the Diphyllobothriinae. The uterus- opening is at the same level with the genital cloaca, and not ahead of it as in the Triaenophorinae. Furthermore, as in most of the subfamilies there is only one set of genitaUa in each proglottis. The testes are situated in the medulla between the nerve strands as in the Haplobothriinae. Unlike the structure in the Triaenophorinae, the receptaculum seminis is large and sharply separated from its continuation, the spermiduct, which also obtains for the Liguhnae, Haplobothriinae, Diphyllobothriinae and Cyathocephalus. The ovary is comparable to that of Triaenophorus, Anchistrocephalus and Anonchocephalus (cf. Liihe, 1902:325) in that it is not exactly in the median line but situated towards the margin bearing the genital cloaca. As in the Triaenophorinae, however, the uterus "nie die sogenannte Rosettenform bildend, vor seiner Mundung meist etwas erweitert, ohne dass indessen diese Erw^eiterung ver- haltnissmassig so betrachtlich ist, "wie die sogenannte Uterushohle der meisten Ptychobothriiden. " This latter difference is further emphasized by the fact that at no stage in its development is the beginning of the uterus, which might be considered at first sight to be a true uterine duct, sharply separated from, the enlarged portion as in the Ptychobothriidae. The outstanding feature that the eggs axe nonoperculate has been noted under the remarks on the family. MARSIPOMETRA Cooper 1917 Dibothrium Linton 1897 Bothriotaenia Ariola 1900 Scolex unarmed, sagittate. Neck present; strobila flat, ribbon-shaped: proglottides ahnost rectangular, posterior borders only slightly projecting. 359] PSEU DOPEY LLIDEA FROM FISHES— COOPER 71 Nerve strands far towards the margins, dorsal to the cirrus-sac and vagina. Testes in two lateral fields united ahead of and behind the uterus-sac and central genital ducts. Vas deferens much coiled proximally, only weakly so close to the cirrus-sac. Receptaculum seminis very long. Ovary reniform, wings tubulolobular, isthmus thick. Shell-gland not in the middle of the genital complex but towards the cloaca, ahead of the ovary. Vitelline follicles numerous, not in two lateral fields but continuous from side to side in the anterior and posterior regions of the proglottis, situated among the body muscles. Uterus-sac pouched, occupying the whole of the medulla dorsoven- trally but not transversely. Uterus opening towards the margin bearing the genital cloaca. — ^apaLirlov a little pouch; /xrjTpa the uterus. Type species: M. hastata Linton. Attention is here called to the great similarity between Marsipometra and Haplobothrium in that each is found in an isolated genus of fishes, respectively Polyodon and Amia, which in turn are relegated to isolated famihes and orders. As suggested previously by the writer (1914) in dealing with Haplobothrium, the unique and generalized nature of these two genera is doubtless due to the great age of their respective hosts. On account of the fact that it has a typical bothriocephalid scolex, Marsipometra would seem to be the younger of the two, for evidently a longer period of time must have been required for the development of the peculiar trypanorhynchous scolex and method of segmen- tation of Haplobothrium, if indeed both are not due to extreme degeneration comparatively speaking. MARSIPOMETRA HASTATA (Linton 1898) [Figs. 4, 5, 46, 47, 68, 83, 100, 101] 1898 Diholhrium hastatum Linton 1898:431 1900 Bothriotaenia hastata Ariola 1900:440 1917 Marsipometra hastata Cooper 1917:36 Specific diagnosis: With the characters of the genus. Medium sized ces- todes up to a length of 1 10mm. with a maximum breadth of 3mm. at the middle. Scolex with deep bothria and prominent posterior borders, 1.5 to 2.8mm. in length, 0.5 to 1.8mm. in width anteriorly and 1.3 to 2.0 posteriorly. Sub- cylindrical neck, 0.8 to 1.5mm. wide. First segments very short and wide, middle much broader than long and rectangular in outline, posterior ones quadrate to slightly longer than broad. Whole strobila much depressed. Cuticula 5n in thickness, subcuticula 40 to 50^1. Calcareous bodies 18 by 13yu. Longitudinal musculature weakly developed, that of scolex strong. Nerve strands 15 to 25 ^i in diameter. Four main excretory vessels in the strobila. Genital cloaca 40 to 60/x in depth, at the middle of the margin of the proglot- tis, irregularly alternating; hermaphroditic duct present, also sphincter cloacae. Vagina opens immediately ahead of the cirrus. 72 ILLINOIS BIOLOGICAL MONOGRAPHS [360 Testes ellipsoidal, 60 to 90)u in diameter, 80 to 120 in number, arranged in a single layer in the medulla and interrupted only centrally. Vas deferens a circular mass of coils, 0.25 to 0.30mm. in diameter dorsal to the uterus-sac, or to one side of it. Seminal vesicle Mathin the cirrus-sac, 50 to 60;u in diameter; cirrus proper slender, 0.20mm. in length, 8 to 15/i in diameter.^ Cirrus-sac elongate, flask-shaped, 0.35mm. in length, llO^u in maximum diameter. Vagina 15 to 20/i in diameter; passes to median line ventrally, then dorsal to the uterus. Receptaculiun seminis median, 90/i in diameter. Ovary reni- form, tubulolobular, 0.45mm. wide and 0.18 long; isthmus thick, ventral. Oocapt 40)u long and 18 in diameter. Two ventral vitelline ducts; comm.on vitelline duct 20/x in diameter. Vitelline follicles irregular in shape and size, forming a continuous layer around the proglottis excepting for median circular areas dorsally and ventrally. Shell-gland small, compact, 115 by 55/i. Uterine duct with only a few dorsoventral coils near the median line. Uterus-sac circular in outhne, 1.0mm. in diameter, divided by deep incisions into 5 to 8 pouches; openings opposite the genital cloaca or slightly behind its level in gravid proglottides almost in the medial line. Eggs, 45 by 36/i. Habitat: Intestine of host. HOST LOCALITY COLLECTOR AUTHORITY Polyodon spathula Ohio R., Wash- E. Linton Linton 1898:431 (type host) ington, Pa. >) j> 111. R., Beards- H. J. Vancleave Cooper (the present town, III. paper) » >» L. des AUemands, Georgia H. B. Ward >» >> )> Mississippi R., Keokuk, Iowa H. B. Ward >» >> » Mississippi R., Fairport, Iowa H. B. Ward 9V T\pe specunen: No. 4724, Collection of the United States National Museum. Type locality: Ohio River, Washington, Pennsylvania. This species was originally described by Linton but with so httle attention to the internal anatomy that up to the present it has remained pretty much a species inquirenda et incerta sedis, as pointed out by Luhe (1899c:40; 1900a: 106); altho Ariola (1900:440) placed it in the now obsolete genus Bothriotaenia RailHet. Linton described the color of the living forms as "... at first lemon- yellow; after lying in water for a few minutes the bodies become colorless or faintly bluish translucent, while the heads remained yellowish. " Regarding their method of attachment he said: "Two pits were found excavated in the mucous and submucous layers of the pylorus near the spiral valve, in which the heads of a number of Dihothria were inserted. The length of the worm was re- 361] PSEUDOPHYLLIDEA PROM FISHES—COOPER 73 corded by the same writer as from 25 to 78mm., while the maximum breadth was 2.7mm. As shown in the table below, the largest examined by the writer was one 110mm. in length with a maximum breadth of 3mm., which, however, showed the characteristic opaque white uterus-sac filled va\h eggs in only the last eight proglottides. The scolex (Figs. 4, 5) and strobila are, as described by Linton, "... sagittate (when at rest and contracted), terminated anteriorly with a button shaped tip [the terminal disc] which is bluntly rounded in front and marked off from the remainder of the head by a slight constriction, in life angled posteriorly; pits [bothria] variable in life but usually elliptical, often with anterior margin acuminate and sometimes with posterior margin indistinct. The head is angled posteriorly both laterally [surficially] and marginally, presenting a quite characteristic appearance in the hving worm. Neck subcylindrical, narrower than the head. The segments begin some dis- tance (6 or 8mjn.) back of the head, as faint transverse lines. The first distinct segments are closely crowded much broader than long, median segments squarish [but still much broader than long], posterior segments usually a little longer than broad, rectangular, apparently separating rather easily. . . . Posterior angles of the segments slightly projecting. . . . OutUne of most of the strobilas nearly linear and about the same breadth as the head. All the segments were remarkably regular in outline, no irregularities being ob- served." While this regularity in the form of the proglottides and in their gradual increase in size anteriorly and change of shape posteriorly is especially noteworthy in this species, the WTiter met with a few cases of intercalated tri- angular and aberrantly subdivided segments in the material studied. It should be emphasized, too, that the whole strobila including even the scolex is constantly much flattened dorsoventrally, which also assists in giving the worm the peculiar diagrammatic appearance which is mentioned below. The following table gives the measurements of four specimens, together with those by Linton in the first two colums for comparison: Length Length of scolex 60mm. 2.75 1.8 45mm. 1.85 76mm. 1.48 0.60 0.43 1.35 1.16 0.87 0.36 0.75 2.32 1.5 1.4 2.38 O.W. 39mm. 1.75 0.55 0.31 1.31 0.96 0.88 0.37 0.46 1.38 0.85 1.10 1.38 O.W. 61mm. 2.34 0.73 0.60 1.83 0.98 1.40 0.48 0.80 2.75 0.90 2.85 3.0 Ale. 110mm. 2.01 Width term, disc 0.80 Depth term, disc 0.42 Width at base 2.0 1.7 1.3 1.95 Depth at base 1.10 Width of neck 1.1 1.52 Depth of neck 0.4 0.35 2.5 0.55 2.7 0.68 Length middle segs 0.73 Width of same 2.44 Length post, segs 1.13 2.0 1.52 Wikth of same 2.44 Maximum breadth 3.0 Measured in water alcohol Formol 74 ILLINOIS BIOLOGICAL MONOGRAPHS [362 The cuticula, 5/x in thickness, consists of two layers of equal thickness, an outer irregular and more darkly staining layer, which is sloughed off in many places, and an inner, more homogeneous and lighter stratum between which the outermost portion of the inner layer shows as a dark bounding membrane. Altho only about one-half as thick on the outside of the scolex and still thinner on the inside of the bothria, it is not modified to form minute spines on the edges of the terminal disc nor hinder end of the scolex where such might be expected to be located. Their absence also on the posterior borders of the proglottides (cf. Haplobothrium glohuliforme) is not surprising since these pro- trude only very slightly. The subcuticula varies from 40 to 50/i in thickness and is made up of narrow elongated cylindrical cells with small nuclei, the outer ends of which are dendritic and quite separate from each other as are the bodies themselves. The meshes of the parenchyma are very loose and open, the spaces being large and the strands of the cytoplasmic framework considerably nar- rower than the small nuclei which are located as usual at the intersections but surrounded by only a limited amount of protoplasm. Linton stated that, "The segments contain numerous calcareous bodies, which exhibit a concen- tric structure. " They are to be found fairly plentiful in all parts of the medulla and cortex and even among the subcuticular cells. They are elliptical or oval in outhne, the largest having dimensions of 18 by \2>n. The musculature of this species, excepting that of the scolex, is compara- tively weak, no one series, not even the longitudinal, being especially strong. All groups are prominent, in that they consist of more or less isolated fibres quite diagrammatically arranged. Their conspicuousness is, indeed, amplified by the fine texture of the parenchyma. The frontal or transverse series do not form a compact layer closely applied to the inside of the longitudinal muscles but, as shown in figure 83, a stratum of varying thickness; owing to the degree of separation of the fibres, especially laterally. The myoblastic nuclei of many of them can be easily seen. The sagittal series are, however, quite prominent, and equally distributed from border to border of the strobila. They show their myoblastic nuclei and surrounding cytoplasm very clearly, reminding one of the dorsoventral muscles of Ahothrium rugosum. While the fibres of both these series are only slightly more numerous opposite the posterior borders of the proglottides, where they form more or less distinct septa, they are very well developed in the neck and anterior segments. The longitudinal muscles form only a single layer of loosely arranged fascicles of irregular size in the middle and posterior segments, but in the neck they form a much thicker stratum, showing no distinct bundles and occupying the whole of the space between the transverse muscles and the subcuticular nuclei. Altho, as above mentioned, the posterior borders of the proglottides are not very prominent, there is a representative series of outer longitudinal muscles, best seen in the middle segments where they are situated close to the longitudinal cuticular fibres with which they are easily confused. Concerning the latter all that need be said is that they are well developed and consist of isolated fibres which render the two layers all the more visible. 363] PSEUDOPHYLLIDEA FROM FISHES— COOPER 75 The musculature of the scolex is, as might be judged from its size and its shape, very powerful. While the longitudinal muscles of the neck merely enter the base of the scolex, the transverse and sagittal fibres are directly con- tinuous with the circular and radial fibres, respectively, of the latter. Here, however, the radial fibres are quite separate from the dorsoventrai fibres with which they are considered to be homologous, especially laterally where they pass from the cuticula lining the bothria to the sides of the scolex as in other bothriocephalids with prominent bothrial walls. Farther forward the sagittal muscles proper passing between the bothria are scarce, their function being taken over by the very numerous and closely arranged radial fibres which are quite as plentiful in the median line as laterally. In the terminal disc both transverse and dorsoventrai fibres are again prominent, while the radial ones are absent. Posteriorly the latter pass dowTi along the sharp edges of the beginning of the neck. Frontal sections demonstrate the presence in the edge of the terminal disc as well as in the posterior borders of the scolex of two series of longitudinal arcuate fibres arranged for the control of these prominent ridges. These are perhaps modified portions of the outer longitudinal muscles which are very numerous in the scolex, and converge in the anterior portions of the edges of the .walls of the bothria to become attached to the edge of the terminal disc at the four respective points. The chief nerve strands, from 15 to 25m in dorsoventrai diameter and from 15 to 20m in lateral diameter, are situated far towards the edges of the medulla and in the median frontal plane or somewhat dorsally (Fig. 83). They pass dorsal to the junction between the lateral and middle thirds of the cirrus-sac and consequently dorsal to the vagina. In the neck they are located in the very borders of the medullary parenchyma, but as they enter the base of the scolex they approach the median line somewhat. As they pass on with a vary- ing diameter towards the tip of the scolex, they give off a number of branches to the walls of the bothria and finally enlarge in the terminal disc to form two ganglia, each with a diameter of about 50m, which send off in turn numerous large branches to the immediate neighborhood. Each of these ganglia is divided into two large trunks which, however, continue only a very short dis- tance farther forward before they are joined by two commissures to their fellows of the opposite side of the scolex in such a way that the two branches of the ganglia on each surface of the scolex are connected. In frontal sections each of these commissures is seen to be bowed slightly forward into the tip of the terminal disc and to give off further forward on each side a large branch which passes farther into the latter. The excretory system consists of a varying number of vessels, of which four pursue a more or less constant course thruout the medulla of the strobila. These are found at all levels in transections and are separated from each other in the transverse direction by different distances. The outermost two, how- ever, are slightly larger and have thinner walls than the innermost pa'r. They give off numerous large branches and are connected by various anastomoses with each other and the more peripheral vessels. In the neck they cannot be 76 ILLINOIS BIOLOGIC A L MONOGRA PHS [3 > 4 followed as well, while close to the scolex they lose their identity and break up into a plexus of very small vessels which ramifies forward thruout the latter. In the posterior border of the scolex, however, a small branch on each side takes a straight course just within the nerve strand for a short distance. Flame-cells are quite numerous and readily discernible especially in the medul- lary parenchyma. In young strobilas where no segments have yet been lost, two comparatively large excretory vessels pass backward to the posterior end and empty into a small narrow terminal vesicle. This in a larva 12.4mm. in length was found to be 40^ long by lO/x wide, while the diameter of the excre- tory vessels was 15^. The earliest traces of the reproductive organs in the form of a transverse line in either half of the proglottis (the rudiments of the vagina, cirrus-sac and lateral portions of the vas deferens) appear from 4 to 10mm. from the tip of the scolex, while the first eggs are seen in the uterus-sacs from 25 to 35mm. from the same point. The development of all of the genitalia is very gradual and can be easily followed in good toto preparations, since the diagrammatic nature of the worm, above mentioned, extends to the reproductive system, making this species an ideal one for study. The ciiTUS and vagina open into a common genital cloaca, which is situated in the middle of the margin of the proglottis, wliile the uterus opens on the ventral surface, not in the median line but towards the side occupied by the atrium. The c-loacae alternate irregularly from side to side, from one to ten having been found occupying the same margin in successive proglottides. The following figures represent the number of such segments before the genital aperture changes to the other side in the fifth specimen of the above table: 1, 2, 1, 8, 1, 1, 1, 2, 2, 3, 3, 1, 2, 2, 10, 1, 1, 1, 3, 3, 2, 2, 1, 4, 1, 1, 2, 2,3, 2, 2, 3, 6, 6, 1, 1, 1, 1, 1,3, 2, 1,3, 3, 2 — as far forward as the rudiments could be conveniently traced. The genital cloaca (Figs. 100, 101) is elliptical in outline when viewed from the side, its longer diameter being directed dorsoventrally, while in transverse sections it is squarish in outline. The dorsoventral diameter, longitudinal diameter and depth are, respectively, 70 to 85m, 40 to 55/i and 40 to 60/i. Into the middle of the bottom of this depression opens the hermaphroditic duct which is about 60jli in length, into the bottom of which in turn opens the vagina immediately ahead of the cirrus. Since the cirrus proper is a long slender tube and since the external portion of the hermaphroditic duct is usually found quite tightly closed and the end of the cirrus turned around toward the opening of the vagina, self-impregnation would seem to be quite probable in this species. On the other hand, the fact that the genital cloaca is so well formed and further that it is surrounded by a well developed sphincter and a series of muscular fibres radiating out into the surrounding parenchyma, as shown in figures 100 and 101, argue in favor of its use in cross-fertilization. No protruded cirri were seen, however, in the material at hand. Perhaps both methods of fertilization occur. The testes are spherical to elUpsoidal in shape, their longest diameters being dorsoventral, while their cross-sections are usually circular in outline. In segments where there are as yet only a few eggs in the uteri their dorsoven- 365] PSEUDOPHYLLIDEA FROM FISHES— COOPER 77 tral and transverse diameters are, respectively, 85 to QOju and 60 to SO/i. In the anterior and posterior ends of the proglottis — they are not continuous from segment to segment but separated by the aggregations of sagittal and transverse muscles mentioned above as forming more or less complete septa — they form a single layer situated in the medulla in the median frontal plane, but are widely separated in the middle of the proglottis by the central genital organs and ducts, especially the uterus-sac. Their number ranges from 80 to 120 for each proglottis. While the wall of the testis consists of a very thin membrane from which nuclei protrude inwardly, the contents are such as to show the process of spermatogenesis quite clearly. The vas deferens forms a circular mass of coils, 0.25 to 0.30mm. in diameter, apphed like a cap to the dorsal side of the developing uterus-sac and thus close to the inner end of the cirrus-sac. When the uterus becomes gorged with eggs it is pushed aside somewhat but still retains similar relations with one of the pouches of the for- mer, located in the direction of the genital cloaca (Fig. 68). In the mass of coils the duct is usually distended with spermatozoa to a diameter of 40/x. It gradually narrows down to a diameter of 15ju before entering the cirrus- sac, before which there is, however, no seminal vesicle. But within the pouch the vas deferens enlarges to form a large seminal vesicle, which with a diameter of from 50 to 60)Lt takes only a few coils before passing on as the cirrus proper from which it is sharply separated (Fig. 101). The cirrus is a slender tube from 0.17 to 0.22mm. in length within the pouch and from 15/i in diameter nearest the seminal vesicle to Spt at its opening. It is lined with a thin cuticula which is circularly cleft in its proximal one-third but alm^ost smooth for the rest of its length, nowhere, however, showing anything in the nature of an armament. The cirrus-sac (Fig. 101) is an elongated flask-shaped structure with a maximum diameter proximally of 1 10/x and distally of 40/Lt, and a length of 0.35mm. The neck of the organ usually shows a couple of dorsoventral curves, while about 20/i of its distal end protrudes into the hermaphroditic duct. Its walls are com.paratively thin and composed of an inner layer of circular muscles and an outer weaker and much less compact layer of longitudinal fibres. Apart from the seminal vesicle which occupies almost the whole of the proximal en- larged portion and the narrow cirrus, the contents consist of only a limited amount of parenchymatous tissue and a very few feeble retractor muscles. The whole structure of the cirrus-sac is in fact such as to suggest that the function is that of an organ for the ex-plusion of spermatozoa rather than for the emission of a copulatory organ; altho a few muscles passing from the body wall around the cloaca to the anterior part of the neck of the sac (Figs. 100, 101) would seem to indicate that a small portion at least of the cirrus is protruded, perhaps during self-fertilization. Altho the vagina opens into the hermaphroditic duct directly ahead of the cirrus, it almost immediately curves around the distal portion of the cirrus -sac to the antero ventral side of the latter which it follows closely towards the median line. Close to the wall of the inner end of the cirrus-sac, however, it crosses the distal coils of the vas deferens towards the dorsal sufrace and 78 ILLINOIS BIOLOGICAL MONOGRAPHS [366 skirts the uterus-sac. When it reaches the median Hne above the sack it turns sharply downward and backward. The vagina has a diameter of from 15 to 20/x opposite the middle of the cirrus-sac and is lined with only a comparatively thin layer of cuticula. It very gradually expands after crossing the inner end of the cirrus-sac to form a much elongated and very spacious receptaculum seminis, the diameter of which close to its inner end may be as much as 90/x. This is usually filled in sections with spermatozoa, a stream of which may often be seen passing on into the spermiduct. The beginning of the duct is surrounded by a poorly developed layer of circiilar muscles which are almost absent from the inner expanded portion. The receptaculum is sharply separa- ted from the spermiduct which has a diameter of only 15 to 20/i and a length of 0.12mm. The latter is an almost straight tube passing in the median line from the more dorsaUy situated receptaculum to its point of union with the oviduct close to the ventral wall of the medulla (Fig. 83). It shows best in transections where its walls are seen to be composed of an epithehum of cubical cells lying on a distinct basement membrane, and to be surrounded with a thick layer of nuclei and extremely few, if any, muscle fibres. The ovary (Figs. 68, 83) is a somewhat kidney-shaped tubulolobular organ situated in the posterior half of the proglottis behind the developing uterus-sac with its con- cavity directed forw-ard, and not exactly in the median Une but sUghtly ap- proaching the cloaca. It averages 0.45mm. in width by 0.18 in length. The isthmus, which is almost as long and about one-half as thick as the wings, is located only slightly below the median frontal plane of the medulla. Ova from the same have a diameter of from 20 to 25ju. In gravid proglottides where the uterus is filled with eggs only a small portion of the degenerating ovary remains, and this is accommodated between the two hindermost pouches of the uterus-sac. The oviduct commences in the median Hne anteroventral to the ovarian isthmus as a somewhat cylindrical oocapt, 40^i in length by 18 in diameter and not sharply separated from the rest of the duct (Fig. 83). It passes ventrally with a diameter of 20jli for about 50jLt before being joined by the spermiduct, and then for only a short distance farther anterolaterally along the ventral transverse musculature before meeting the common vitelline duct. The latter is formed by the union in the usual manner of two vitelline ducts coming from the lateral regions of the proglottis along the ventral wall of the medulla. It is quite short, however, and usually contains only a limited amount of yolk, its diameter being at the most only 20^. The vitelhne follicles (Fig. 83) are irregularly eUipsoidal in shape, and situated either just within the transverse muscles, between them and the longitudinal muscles, among the latter or even slightly outside of the longitudinal muscles. While they vary considerably in size and, not being very numerous, are widely spaced, their average maximum diameter is about 50/x. They form a continuous band completely surrounding the medulla, excepting for irregularly circular areas above and below the ventral ducts and organs, in the median line, but are not continuous from joint to joint. On the whole they remind one of the vitellaria of A. crassum. The union of their different ductlets can be easily traced, 367] PSEUDOPHYLLIDEA FROM FISHES— COOPER 79 especially in frontal sections of younger proglottides, since they are com- paratively large and hence quite distinct. The shell-gland is a small compact organ, about 11 5^ in width by 55/x in length, surrounding the oviduct just beyond the entrance of the vitelline duct, or to be more exact, just beyond the first turn taken by the latter in its return to the median line after passing laterally, as above stated. It is thus situated ventrally and a short distance from the median line. Beyond the shell-gland the oviduct continues as the uterine duct which takes only a few dorsoventral turns near the median line before emptying into the uterus-sac. The latter is formed in development by the gradual enlargement dorsally of that portion of the duct which traverses the cortical parenchyma on the ventral surface of the proglottis. Just before eggs appear in the sac this part of the tube can be seen in transections as a spindle-shaped dilatation, whose nucleated epithelial wall is surrounded by a thick layer of nuclei, the whole being, however, not distinctly separated from the proximal portion of the tube (the uterine duct of older stages) at a constric- tion just within the transverse musculature. In proglottides farther ahead this constriction is outside of the transverse muscles in the cortex; so that the uterus-sac must be looked upon, then, as being formed by a gradual enlarge- ment of the distal end of the uterus as it becomes filled with eggs and not as a sac separated in the rudiments from the proximal uterine tract as in the Ptychobothriidae. In one case where only 5 or 6 eggs appeared in the lumen the uterus-sac had a diameter in frontal sections of 80.u; in the next segment following it was enlarged in all directions, somewhat elliptical in outline, with a diameter of 240/x; in the next still larger; and in the fourth somewhat pointed anteriorly. From this region on it quickly enlarges until finally it forms a capacious sac, as much as 1.0mm. in diameter, occupying in gravid proglottides the whole of the dorsoventral diameter of the medulla and almost all of the longitudinal and transverse diameters. In transverse sections it is almost entire in outline, while in frontal sections it is divided into from .S to 8 large irregularly shaped lobes or diverticula, the hindermost two of which enclose the remainder of the ovary and the central connections of the reproductive ducts, as above mentioned. Ventrally, the sac is funnel-shaped towards the small opening which only appears when the proglottis becomes quite gravid. Since the uterus-sacs, even the most gravid ones, are not situated exactly in the median line but towards the margins bearing the genital cloacae, the openings form " ... a zig-zag line of minute pores [which] traverses the median region of one of the broad faces of the strobila, each pore being near the middle of its segment." Linton correctly considered them to be for the escape of the eggs. Anteriorly, where the uterus-sacs do not yet con- tain eggs, these pores — in reality the ventral funnel-shaped portions of the sacs — are located about 0.18mm. on each side of the median line, but posterior- ly they are relatively much closer together, in fact almost exactly in the median line. Furthermore, they are situated directly opposite or slightly behind the level of the genital cloaca. The opening is formed by the rupture of the body 80 ILLINOIS BIOLOGICAL MONOGRAPHS [368 wall in a very small and limited area, and not of a preformed membrane as in the Ptychobothriinae. Concerning the eggs Linton (p. 433) said: "The ova are nearly spherical, with thin shells. They are about 0.04mm. in the greatest diameter. " Those from material preserved in formalin were foimd by the writer to be sometimes spherical in shape but usually ovoid or ellipsoid, with maximum dimensions in the latter case of 45 by 36/x. Neither in sections nor in preparations of eggs from the uterus sacs of material in formol, alcohol or cleared in oil of wintergreen were opercala to be found, but at the one pole of the egg a small boss about 5m in diameter which is often enlarged to form a distinct projection or appendage. Altho development had not progressed in any of the eggs studied so far that the six hooks of the oncosphere were visible, the writer is of the opinion that even in mature eggs no opercula would be found, since its almost spherical shape and the presence of the button-like thickening at one pole are quite like conditions in the nonoperculate egg of Abothrium rugo- sum, for instance, as described and figured by Schauinsland (1885:527) and further, since in the egg of the operculate type, as in that of D. latum or of T. nodtdosus, described and figured by the same writer, the operculum is present long before the hexacanth embryo has developed. As regards the Mfe-history of this species nothing is as yet known. It is noteworthy, however, that very young larvae, such as shown in figures 46 and 47, can be easily recognized on account of the peculiar character of the scolex, so that it would not seem difiScult to pick them out of the intermediate host whatever that may be. AU sizes from the youngest (Fig. 46) to the lar- gest were present in the material studied. The material of this species consisted of Nos. 4724 and 4783 of the collection of the United States National Museum, Nos. 16.292, 16.421 and 17.11 of the collection of the University of Illinois and No. 154 of the writer's collection, all from the intestine of Polyodon spathula, the paddlefish. 369] PSEU DOPEY LLIDEA FROM FISHES— COOPER 81 TRIAENOPHORINAE Liihe 1899 Scolex armed or unarmed, always with two t)T3ical and not very deep bothria, ahead of which the flattened termination of the scolex projects more or less prominently in the form of a ring. External segmentation present or absent, in the former case an unjointed neck being absent. Opening of cirrus and vagina marginal, irregularly altematiag; uterus opening surficial, ventral, ahead of the marginal genital aperture. Genital apparatus always single in each proglottis. No muscular bulb (Eschricht's body) on the inner end of the cirrus-sac. Receptaculum seminis comparatively small, not always sharp- ly separated from the narrow iimer end of the vagina. Uterus a much coiled canal, which while never forming a rosette is usually somewhat enlarged before its opening. Sexually mature in the intestines of fishes and marine turtles; larval condi- tions mostly unknown. Type genus: Triaenophorus Rudolphi. TRIAENOPHORUS Rudolphi 1793 Vesicaria, Cysticerois et Taenia (omn. part.) Auctorum Triaenophorus vel Tricuspidaria Rudolphi 1793 Tricuspidaria Rudolphi 1793 Triaenophonis Rudolphi 1793 Rhytelminthus (part.) Zeder 1800 Rhytis (part.) Zeder 1803 Tricuspidaria Rudolphi 1802 Trioispidaria Rudolphi 1809 Triaenophorus Rudolphi 1809 Tricuspidaria Rudolphi 1810 Tricuspidaria Lamarck 1816 Triaenophorus Rudolphi 1819 Triaenophorus Creplin 1839 Triaenophorus Dujardin 1845 Triaenophorus Diesing 1850 Triaenophorus Baird 1853 Triaenophorus Molin 1858 Triaenophorus Molin 1861 Triaenophorus Diesing 1863 Triaenophorus Olsson 1867 Triaenophorus Lonnberg 1889 Triaenophorus Olsson 1893 Triaenophorus LUhe 1899 Triaenophonis Ltihc 1899 Triaenophorus Braun 1900 Triaenophorus Liihe 1900 Tricuspidaria Stiles and Hassall 1902 Triaenophonis Liihe 1910 82 ILLINOIS BIOLOGICAL MONOGRAPHS [370 Scolex armed with four three-pointed hooks, never replaced by a pseudosco- lex. External segmentation completely absent. Longitudinal nerves dorsal to the cirrus-sac and vagina, close to the lateral borders. Testes between the nerv^e strands only, filling up the whole medullar}- parench\ana so far as this is not occupied by other organs; a testis-free middle field is quite as infrequently present as a pronounced dorsal layer of the testes. Coiling of the vas deferens in its proximal almost medially situated part, that portion passing distad to the cirras-sac only vexy shghtly coiled. Vitelline follicles form a continuous mantle between the subcuticula and the longitudinal musculature, which is broken only at the places where the genital ducts open. Ovary, approaching the lateral bor- der bearing the genital openings, lies on the ventral transverse musculature, yet individual ovarian tubules extend partly thruout the whole medulla. Shell- gland just as infrequently median as the ovary lying behind it, also usually approaching the dorsal surface somewhat. First portion of the uterus only a weakly coiled canal (uterine duct) which passes thru the proglottis transverse- ly and leads into a large single cavity (uterus-sac) which lies not exceptionally ahead of, but yet partly near the ovary, and usually not median but away from the margin bearing the genital openings. The latter also applies naturally to the uterus-openings which breaks thru later. Eggs thick-shelled, operculate. Type species: T. nodulosa (Pallas 1781) Rudolphi 1793. As indicated in the above s}Tionymy the name Triaenophorus has absolute page priority altho Stiles and Hassall (1902:22) have contended that Rudolphi should not have changed the name of the genus in 1819 from Tricuspidaria to Triaenaphorus again, after havdng used it in connection with the specific description in 1810. The change has become so universally established in the literature that it does not seem justifiable to revert to the name Tricuspidaria which is known to only a comparatively small group of zoologists. TRIAENOPHORUS sp. larv. [Figs. 12-18] Since all of the material at hand was larval, not even the earliest traces of the reproductive rudiments showing in toto preparations of the largest speci- mens, it was, of course, impossible to determine the species with certainty. Two types of scolices are present, however, and these agree with the de- scriptions of the organ given by various authors for T. nodidostis (Pallas) and by Olsson (1893:20) and Fuhrmann (1910:88) in particular, for T. robustiis Olsson. It will be seen also in the table below that these two forms are found respectively encysted in the liver, on the visceral organs, or in the wall of the stomach, and encysted in the muscles or free in the intestine of the hosts — in the latter case so firmly attached to the wall as to be deeply imbedded, the mucosa forming a protruding collar around the worm — the only exception being those from the intestines of Esox masquinongy and Stizostedlon vitreum {vide infra). Olsson pointed out that these two species can be readily differ- entiated from each other on account of the situations in which they undergo their development. Whereas the larvae of T. nodulosus are found generally 371] PSEUDOPHYLLIDEA FROM FISHES— COOPER 83 within cysts in the liver of the intermediate hosts, as recorded by a number of writers, those of T. rohustus are constantly encysted in large numbers in the flesh — Olsson having found them in Coregonus albula and C. lavaretus, Luther (1909:58) in C. albula, and Fuhrmann in the "brochet" (? Esox lucius). The scolex of the rohustus type (Figs. 12 and 13) is, as described by Olsson, in the form of a truncated rectangular pyramid, that part immediately behind the terminal disc being considerably constricted and more nearly elliptical in transverse section. As stated by Fuhrmann. "La limite posterieure du scolex de T. rohustus est nettement marquee et les deux bothrias, I'un dorsal I'autre ventral, son tres profonds. ..." This delimitation of the scolex is emphasized by the fact that immediately behind the posterior border of the bothria the dorsal and ventral surfaces of the body of the larva are distinctly concave as are also the lateral surfaces, quite diagrammatically, in fact, as shown in the figures. These concavities extend farther back for a few milli- meters and then gradually flatten out and pass insensibly into the convexities which together form the elliptical outline of the cross-section of the middle of the larva. And it should be emphasized that this was found to be a con- stant feature of all the material studied and not simply due to any possible local collapsing during dehydration. Altho, as shown in the table, the measure- ments of the whole scolex are much smaller than those given by Fuhrmann, as might be expected it is chiefly the structure and size of the trident of hooks that leads the writer to consider this type of larva to belong to T. rohustus. Figure 14 of one of these compares very favorably with those shown in Olsson's figures 31 and 32 and Fuhrmann's figure 2, while the measurements (see table) quite agree with those given by the latter. The base of the trident is com- paratively long or deep (in the sagittal direction), hence the specific name according to Olsson, while not only the full length of the larger hooks but also a good deal of the median ones project thru the cuticula as the functional tips. In figure 14, which is from an alcoholic specimen, these are seen to be darker than the basal piece. The following measurements are given for comparison with Fuhrmann's of adult specimens, which are placed alongside, the data in parentheses being of the opposite trident on the same surface of the scolex in question : Host Esox lucius Leucichlhys arledi After Furmann Length 147.5mm. 123.0m. 183.0mm. 47.0mm. 310-370mm. Breadth (maxi- mum) 1.07 1.16 0.98 1.10 4.00-4.50 Length of sco- lex 0.98 0.96 1.02 1.12 1.14-1.50 Breadth of term. disc. 0.77 0.83 0.84 0.84 0.95 Breadth of sco- lex poster- ly 1.05 1.07 1.30 1.08 1.40-1.50 84 ILLINOIS BIOLOGICAL MONOGRAPHS [372 Host Esolucius Leimchthes arledi After Fuhrmann Width of tri- dent 0.31(0.30) 0.30(0.30) 0.32 0.28 0.29-0.32 Length, mediad 0.25(0.24) 0.23(0.23) 0.27 0.22 0.24-0.28 Length, exter- nally 0.18(0.18) 0.16(0.18) 0.24 0.18 0.18-0.20 Measured in Oil of wintergreen Alcohol Olsson spoke of the larva of T. robustus being provided with a narrower cylin- drical " Cauda" as in certain Tetrarhynchus larvae, and gave the length of one as 120mm., while the anterior portion was approximately 60mm. long. Such structures were seen posteriorly in many of the larger larvae at hand but their lengths and degrees of distinction from the fore-body varied considerably. A medium large one, in a lot from Esox lucius, for instance, had these measure- ments: Length of anterior portion, 48mm., of cauda 24, of scolex 1.16; width of forebody 0.66, of cauda 0.37 (3:1 — Olsson). The specimen from Leucich- thys artedi dealt with in the third column of the above table possessed a cauda 110mm. in length, while that treated in the fourth column had no posterior appendage at all. As for its anatom.ical structure this organ is characterized by very poorly developed cuticula and musculature, and a very loose or open parenchymatous mesh-work. As may be seen by reference to the host record given below the specimens taken from Leucichthys artedi were the only ones belonging to this type of larva which were found encysted. From 26 specimens of the host examined by the writer, 14 cysts, each containing a single larva, were taken. Each fish harbored one or two cysts, but one contained four. The cysts themselves are from 15 to 45mm. in length and 2 to 3mm. in diameter, and cylindrical in shape, with bluntly pointed ends. They are often attentuated at one end to such an extent that at first sight they appear to be terminated by a mere thread. This is found, however, on closer examination to be hollow and to place a more distal, but somewhat smaller portion of the cyst in com.munication with the main body. In situ these cysts are located constantly in the myocommata of the dorsal musculature of the host, from a short distance back of the dorsal fin to close behind the skull, and with their longitudinal axes directed down- ward, inward, and forv/ard towards the spinal column, or, indeed as was seen in one case, actually towards the dorsal aorta. Often they are found doubled on themselves in a V-shaped manner. Their translucent white or somewhat opalescent color is due to the contents, which besides the worm coiled on itself several times consists of a caseous substance, showing thru the thin wall. On the other hand, the other type of larva which is considered by the writer to belong to T. nodiilosus, is characterized by a much shorter, narrower body, smaller at irregular intervals owing to differences of contraction, whence the specific name, and by a quite different scolex provided with the well- 373] PSEUDOPHYLLIDEA FROM FISHES— COOPER 85 known form of trident (Figs. 15 to 16). While the latter and the scolex as seen in surficial view agree in essentials with the descriptions and figures given by- various authors, e.g., Rudolphi (1810:32, Tab. IX, Figs. 6-11), Wagener (1854: 26, Tab. 2, Figs. 17-21), Olsson (1893:20, Figs. 28-32) and Fuhrmann (1910:86, Fig. 1), it cannot be said of the material studied that, as stated by the last writer, " . . . chez T. nodulosus on ne pent voir aucune limite entre le scolex et le cou du Bothriocephale. ..." For in lateral view (Fig. 16) the bothria are distinctly separated from the beginning of the body, which is, as just men- tioned, not nearly so apparent in surficial view. As shown in figure 15, the middle hook of the trident scarcely protrudes thru the cuticula, since it is the root for muscular attaclmient. The upper median hook (cf. Wagener) which does protrude in the adult is evidently not yet developed (Figs. 17 and 18). For a short distance behind the scolex the body is somewhat rectangular in cross-section, the sides of the rectangle being, however, slightly convex and not concave as in the rohustus t>'pe, and hence not so very different from the cross-section of the body farther back. But the material contained in the lot from the intestine of Esox masquinongy does not strictly answer this de- scription since the body just behind the scolex is slightly concave on all sides. Otherwise the specimens are distinctly of the 7iodulosus type. It should be mentioned, too, that one of this lot showed a very short but distinct caudal piece; but this with the general stout appearance of all of them may be account- ed for by the possibility that they have reached the intestine of one of their final hosts and continued their development. Likewise a few of the specimens of the lots from the "white bass" and Stizostedion canadense were provided with short caudal appendages. The smallest example of this type and of all the material, for that matter, at hand was that from Micropterus dolomieu of the accompanying table. Altho it is only a little over two and a half millimeters in length, its posterior end shows that a portion, perhaps a caudal piece, has been torn away. The following table gives measurements of a number of specimens of the nodulosus type, similar to those given above for the robustus type, with Fuhrmann's data for comparison: Catostomus Esox Micropterus Host commersonii masquinongy dolomieu After Fuhrmann Length Piece Piece Piece 2.68 120-180mm. Breadth at middle 0.61 0.37 0.42 0.30 2.50-4.00 Length of scolex 0.92 0.63 0.55 0.55 0.95 Width term. disc. 0.42 0.35 0.37 0.31 0.37-0.47 Width of scolex posteriorly 0.64 0.37 0.37 0.26 0.57-0.60 Width of trident 0.19 0.15 0.15 0.13 0.125 Width of trident medially 0.14 0.13 0.11 0.14 0.073 Width of trident externally 1.11 0.09 0.08 0.10 0.062 Measured in Oil of win tergreen 86 ILLIXOIS BIOLOGICAL MONOGRAPHS [.v4 It will be noticed that in spite of the fact that all of the measurements of the tridents are larger than those given by Fuhrmann, they are considerably smaller than those of the other type. Finally, altho no specimens of either type of larva so young that the hooks had not yet developed were met with, those from the intestine of Stizostedion mtreum were provided with only very small tridents of the nodidosns form, the bases of which were not yet well developed. The whole scolices were a sort of compromise between the two types in shape but of the nodulosiis type as regards size, as shown in the following measurements: Length, 12mm.; width at middle, 0.64; length of scolex, 0.87; width of terminal disc, 0.64; same of scolex posteriorly, 0.80; width of trident, 0.14, length medially, 0.07, ex- ternally, 0.05. Altho these specimens would seem to represent an intermediate stage between the two types of scolex so far as the general shape is concerned, the writer was inchned to consider them as belonging to the nodulosus type; yet it must be said that smaller scolices, e.g., those from M. dolomieu in the table, have considerably larger hooks. On the whole, then, the bulk of the e\ddence given here tends to show that here in America there are probably two species, very closely related to, if not identical \vith, the European T. nodulosus and T. robustus which have been clearly distinguished by Fuhrmann (1910) and also recognized by Liihe (1910: 23). However, no adults have as yet been reported for this continent, so far as the writer is aware. The material studied is here listed as a host record also: LOT HOST LOCVTION LOCALITY COLLECTOH Type robustus: Esox lucius 36 Intestine Flat Rock L. Cooper Muskoka, Ont. 36a, 36b, 36c Esox lucitis Intestine Go-Home R., Muskoka, Ont. Cooper 161, 163, 183, Esox Indus Intestine Go-Home Bay, Cooper 162 Lota maculosa Intestine Off Giant's Tomb Id., Georgian Bay, Lake Huron Cooper 15.47 "Lake Herring" ? Intestine Lake Superior H. B. Ward 186a, 194b, LeucichthMS ariedi Muscles Douglas Lake, G.R.LaRue 195a, 196a, Michigan 197a, 25f, 25g 331, 333, 336, Leucichthys ariedi Muscles Douglas Lake, Cooper 337 Michigan 375] PSEUDOPHYLLIDEA FROM FISHES— COOPER 87 T>'pe nodulosus: Ho?t Location Locality Collector 71 Perca flavescens In liver St. Lawrence R., Iroquois, Ont. Cooper 151, 188 Micropterus dolomieu In viscera Go-Home Bay Cooper 195 Caiosiomus commer- sonii ? Georgian Bay Cooper Eh3b Noiropis delicatus ? Charlevoix, Midi. H. B. Ward 10213 "WTiiteBass" Liver ? H. B. Ward N. S. 28a Stizosledion canadense Stomach wall New Baltimore, Michigan H. E. Ward 40 S. viireum Intestine Flat Rock L. Cooper 35 Esox masquinongy Intestine Go-Home R. Cooper ILLINOIS BIOLOGIC A L MONOGRA PES [376 FISTULICOLA Liihe 1899 Taenia (part.) PaUas 1781 Bothriocephalus (part.) Rudolphi 1819 Bothriocephalus (part.) Leuckart 1819 Bothriocephalus (part.) Dujardin 1845 Dibothriiim (part.) Diesing 1850 Dibothrium (part.) Diesing 1863 Bothriocephalus (part.) Linstow 1878 Bothriocephalus (part.) Cams 1885 Bothriocephalus (part.) Matz 1892 Bothriotaenia (part.) Ariola 1896 Bothriotaenia (part.) Riggenbach 1896 Fistulicola Liihe 1899 Bothriotaenia (part.) Ariola 1900 Fistulicola Braun 1900 FistuUcola Liihe 1902 Scolex unarmed, arrow-shaped (since the posterior borders of the surficial bothria protrude comparatively strongly), may be replaced by a pseudoscolex. Neck absent. Chain of proglottides very thick, so that transections may be nearly circular. Segmentation strongly expressed, the individual proglottides very short with leaf-Uke, free lateral portions. Longitudinal nerves strongly approaching the lateral borders; individual testes, however, are also present outside of them. Pronounced coiling of the vas deferens in its proximal por- tion; the distal part near the cirrus-sac only weakly coiled. Receptaculum seminis comparatively small and obscure, but at the same time sharply set off from the narrow terminal portion of the vagina (the spermiduct), which in contrast with the Ligulinae, Dibothriocephalinae and Cyathocephalinae is comparatively long. Ovary and shell-gland, near the corresponding parts of the female ducts, are, in consequence of the shortness of the proglottides and the strong development of the uterus, forced away from the position which they usually occupy in the Dibothriocephalidae, or towards the ventral surface or the margin bearing the genital openings. Vitelline follicles extraordinarily numerous, not confined to two lateral fields, but in the form of a ring, outside of the longitudinal musculature in the free lateral leaf-like portions of the proglottides. Uterus a comparatively wide, strongly coiled canal; that portion near its opening very muscular. The eggs pass thru their embryonic develop- ment (at least for the most part) in the uterus. Type species: F. plicatus (Rudolphi). 377] PSEUDOPEYLLIDEA FROM FISHES— COOPER 89 FISTULICOLA PLICATUS (RudolpH 1819) 1781 Taenia haeruca 1790 Echinorhynchus xiphiae 1803 Echinorhynchus xiphiae 1809 Echinorhynchus xiphiae 1816 Echinorhynchus xiphiae 1819 Bothriocephalus plicatus 1819 Bothriocephalus truncatus 1829 Bothriocephalus plicatus 1839 Bothriocephalus plicatus 1845 Bothriocephalus plicatus 1850 Dibothrium plicatum 1854 Dibothrium plicatum 1863 Dibothrium plicatum 1869 Bothriocephalus plicatus 1871 Dibothrium plicatum 1878 Bothriocephalus plicatus 1885 Bothriocephalus plicatus 1890 Dibothrium plicatum 1892 Bothriocephalus plicatus 1896 Bothriotaenia plicata 1896 Bothriotaenia plicata 1896 Bothriotaenia plicata 1898 Dibothrium plicatum 1898 Bothriocephalus plicatus 1899 Fistulicola plicatus 1899 Fistulicola plicatus 1900 Bothriotaenia plicata 1900 Fistulicola plicatus 1900 Fistulicola plicatus 1901 Dibothrium plicatum 1901 Dibothrium plicatum 1902 Fistulicola plicatus 1903 Bothriotaenia plicata 1905 Fistulicola plicata 1914 Fistulicola plicatus Pallas Gmelin Zeder Rudolphi Lamarck Rudolphi Leuckart Creplin Creplin Dujardin Diesing Wagener Diesing Cobbold Van Beneden Linstow Cams Linton Matz Ariola Ariola Riggenbach Linton Muehling Liihe Liihe Ariola Braun Liihe Linton Linton Liihe Barbagallo and Drago Spengel Rudin 1781 : 1790 : 1803 : 1809 : 1816 : 1819 : 1819 : 1829 : 1839 : 1845 : 1850 : 1854 : 1863 : 1869 : 1871 : 1878 : 1885 : 1S90 : 1392 : 1896 1896 : 1896 : 1898 : 1898 : 1899 : 1899a 1900 : 1900 : 1900a 1901 : 1901a: 1902a 1903 : 108 3047 162 308 582 136, 470 37 87 297 614 591 71 243 71 36 218 120 746 117 280 223 430 36 37 437 1695 : 98 267 412,448 : 321, 324, 329 412 1905 : 273 1914 :321 Specific diagnosis: With the characters of the genus. Large cestodes with maximum length, breadth and thickness of 250 (about 60 when contracted), 20 and 5mm, respectively, Scolex somewhat orbicular, 2mm, long, 1.3 wide and 1.8 thick; present only in young strobilas which are free in the intestine of the host; later it becomes modified as does a considerable portion of the anterior end of the strobila to form a pseudoscolex which is found deeply im- bedded in the wall of the host's rectum or completely piercing it. Segmenta- tion begins immediately behind the scolex or pseudoscolex. First and middle segments very short and broad, with prominent posterior and wavy borders; posterior joints 0.4, 7 and 3mm. in length, breadth and thickness respectively, funnel-shaped with prominent posterior borders which occupy two-thirds or more of the transverse diameter; terminal segments relatively much longer, narrower and conical in shape, their posterior margins very thin and leaf -like. 90 ILLIXQIS BIOLOGICAL MONOGRAPHS [378 Cuticula 10/x in thickness, subcuticula 50 to 55ju. Calcareous bodies 15 to 25 by 10 to 15At in dimensions, mostly outside of the longitudinal muscles. Latter not in bundles but distributed thruout the cortical parenchyma, separa- ted into outer and inner groups only in young proglottides. Transverse and sagittal fibres likewise diffuse, former more numerous, however, just outside of the medulla. Chief nerve strand 45/i in diameter, situated far towards the margin of the strobila on each side, passing dorsal to the cirrus-sac and vagina. Excretor}' system in the form of a plexus of vessels ramif>'ing thruout the whole of the medulla, of which one just within the nerve on each side is small in caliber but provided with thick muscular walls. No genital cloaca, but the vagina opens immediately behind the cirrus-sac, the outer half of which forms a protruding papilla from 0.4 to 0.6mm. in length and with a marked constriction at its base. Uterus opening about half-way between the median line and the margin bearing the other genital apertures, and on the free posterior portion of the proglottis. Testes polyhedral in shape; closely arranged, forming a dorsal layer con- tinuous from side to side but discontinuous from proglottis to proglottis; 90 to 130, 55 to 75 and 90 to 185pt, in length, breadth and thickness respectively; quite numerous outside of the nerve strands, at least 200 to each proglottis. Vas deferens strongly coiled and compact in the median line, less coiled lateral- ly; median and distal portions lined with ciliated epithelium; no special en- largement at any point in its course to form a vesicula seminalis. Cirrus-sac 0.5 to 0.7mm. in length by 0.2 to 0.4 in maximum diameter; outer half or more forming the pyriform, protruding cirrus, the cuticula over which is deeply cleft. This functional cirrus may be augmented in length by the further evagination of the cirrus proper from the papillary portion of the organ. Immediately within its opening the vagina is surrounded by a sphincter, 0.2mm. in diameter, which is followed by a slight enlargement of the lumen to a diameter of 60/i ; much coiled laterally but straighter medially; 20;u in diameter at the middle of its course; spermiduct inconspicuous. Ovary irregular in shape, median in position and considerably depressed, 0.7mm. in transverse diameter by 0.1 in thickness, isthmus prominent, ova from same 25^1 in maxi- mum diameter. Oocapt 25/i in diameter, oviduct 40At. Vitelline reservoir 75m in diameter when filled with vitelhne material. Vitelline follicles irregular in shape, very numerous; discontinuous from proglottis to proglottis, but form a continuous layer laterally and dorsoventrally in the free posterior borders of the segments. Shell-gland inconspicuous. Uterus in gravid joints occu- pies almost the whole of the medulla; 0.16 to 0.20mm. in diameter at its middle; the terminal portion quite muscular, and sharply separated from the duct immediately before it, 0.2 to 0.3mm. in length by 0.10 to 0.15 in diameter; opening irregular in shape and size. Eggs thick-shelled (2 to 4^) with dimensions of 0.09 to 0.10 by 0.05 to 0.06mm. Habitat: In the rectum — less frequently in the stomach and anterior por- tion of the intestine — of the host. 37' PSEUDOPHYLLIDEA FROM FISHES— COOPER 91 HOST LOCALITY COLLECTOR AUTHORITY Xiphias gladius (type host) Pisa Redi Rudolphi 1809 : 30') Xiphias gladius Baltic Sea Rudolphi Rudolphi 1819 :471 Xiphias gladius Ticini Spedalieri Diesing 1850 : 591 Xiphias gladius Kais.-Koni^ T.piipl'q rf 1819 : 37 Nat'l Kab. J^CUL-tVLli L Xiphias gladius Xiphias gladius Dujardin Diesing I.oAt • fiu Gryphswald Rosenthal 1850 : 591 Xiphias gladius Xiphias gladius M. C. V. Diesing Cobbold 1850 : 591 1869 :71 Lynn, Norfolk, Cobbold England Xiphias gladius Coast of Norway Olsson Eeneden 1871 : 36 Xiphias gladius Xiphias gladius Xiphias gladius Escaut T^Piiprlen 1871 : 36 Holland Ronpflpn 1871 : 36 Firth of Forth, 1871 • 36 Edinburgh LJ \.li\_ \-l\^L L XkJ i X . yJXJ Xiphias gladius Nizza Wagener Carus 1885 : 120 Xiphias gladius Martha's Vine- yard, Mass. Linton Linton 1890 : 750 Xiphias gladius Geneva Ariola Ariola lS96a : 121 Xiphias gladius U. S. National Linton 1S9S : 430 Museum .l„^ 1. I 1 ^ V^ t i. Xiphias gladius Konigsberg Braun Muehling 1898 : 35 Xiphias gladius Siracusa Condorelli Ariola 1900 : 438 Xiphias gladius Naples Ariola Ariola 1900 : 438 Xiphias gladius Casco Bay, Me. U. S. National Museum Linton 1901a : 448 Xiphias gladius Woods Hole, Mass. Linton Linton 1901a : 448 Xiphias gladius Messina, Italy Barbagallo and Drago Barbagallo and Drago 1903 : 412 Xiphias gladius Messina, Italy Janicki Rudin 1914 : 321 Xiphias gladius Woods Hole, H. E. Ward Cooper (the present Mass. paper) "Sunfish" (Mola ?) Woods Hole, V. N. Edwards Cooper (th( i present Mass. paper) This species has been so well described by Linton (1890:746), Ariola (lS96a) and Liihe (1899a, 1900a) that little need be added. The writer would like to point out, however, that as regards a few details the material studied did not agree with the descriptions given by these writers. After referring to the fact that the testes are not arranged in two lateral fields but form a continuous dorsal layer and the further fact that, contrary to Ariola's statement, they are to be found evidently functioning in gravid segments, Llihe (1899a :709) stated that "Ihre Anzahl ('pochi' nach Ariola, 'zahlreich' nach Loennberg) betragt ca. 50 pro Proglottis." In the sections made they were found to be about 200 in number for each proglottis, and sepa- rated from those of the segments ahead and behind by aggregations of trans- verse and sagittal muscles which are, however, so narrow as to give the closely 92 ILLINOIS BIOLOGICAL MONOGRAPHS [380 crowded organs the appearance at first sight of being continuous thruout the strobila. The vagina was described by Liihe ( 1900a :68) as being provided with no cuticular lining within the enlargement just beyond the sphincter, but in the sections made by the writer the cuticula could be followed for about half the length of the whole duct. Peripherally as in the case of that lining the terminal enlargements, it was seen to be thrown into prominent longitudinal folds which in transections were in many places fused together so as to divide the lumen into several passages. Farther on these folds become less pronounced and fused, while their borders towards the center of the lumen gradually become broken up into pseudocilia. Beyond the middle of the course of the duct these pseudociHa seem to pass insensibly into the cilia of the proximal region, while the cuticula is likewise strictly continuous with the nucleated epithelium, there being no distinct region, let alone line of demarcation in either case. It would appear, then, that what are apparently true cilia in the proximal portion of the duct are merely modified cuticular pseudocilia; or from the standpoint of development that the latter, as well as the more peripheral ridges, are formed by the gradual fusion of the former from within outwards. But since this view needs considerable ontogenetic evidence for its support, it must re- main for the present, at least, a mere suggestion of possibility. Otherwise the material studied, which was quite fragmentary, corresponded with the descriptions given by the various authors of the species found on the European side of the Atlantic Ocean, as was brought out by Linton (1890) for the general features. It consisted of No. 13.46 of the Collection of the University of Illinois from the stomach wall of Xiphias gladius, and one speci- men taken by Mr. V. N. Edwards from a "Simfish" (? Mola mola) at the Woods Hole Laboratory of the U. S. Bureau of Fisheries. 381] PSEU DOPEY LLIDEA FROM FISHES— COOPER 93 PTYCHOBOTHRIIDAE Liihe 1902 Scolex unarmed, with two separate and more or less strongly developed bothria, or exceptionally replaced by a pseudoscolex. Neck absent. External segmentation never absent, but frequently incomplete or obliterated thru secondary foldings. Genital organs numerous, but only single in each proglot- tis. Both surfaces of the chain of proglottides, apart from the genital openings similar. Cirrus unarmed, with cleft cuticula. Opening of cirrus and vagina behind the uterus opening, surficial or marginal, in the first case on the opposite surface to the uterus-opening and almost median. No muscular bulb at the inner end of the cirrus-sac. Receptaculum seminis, when present, has the form of a small blind sac situated at the inner end of the vagina. Ovary and shell-gland median. Testes in two lateral fields. Uterus never taking the rosette shape, but usually forming a capacious undivided uterus-sac. Eggs thin-shelled, without opercula; embryonic development in the uterus, and in consequence of exhaustive production of eggs (but dependent on the time of year in the case of many species) all the eggs of the whole tapeworm are at the same stage of development. Sexually mature in the intestine of fishes; larval condition unknown. In his first diagnosis of the family Liihe (1902a:326) emphasized the similar- ity of both surfaces of the strobila (in contradistinction to conditions in the AcanthophaUidae), the unarmed cirrus with cleft cuticula, the peculiar cecal receptaculum seminis and the absence of opercula in the eggs, but described the uterus as follows: "Uterus nie die sogenannte Rosettenfonn annehmend, wohl aber in der Regel eine geraumige Uterushohle bildend, welche die iibrigen Genitalorgane, ohne dass freiUch deren Riickbildung eintritt, buchstablich an die Wand drangen kann, indem die ganze Proglottis in reifen Proglottiden viel- fach als ein einziger sackformiger Eibehalter mit verhaltnismassig sehr diinnen Wandungen erscheint. " The uterus of Haplobothrium answers this descrip- tion in that it is divided into a uterus-sac and uterine duct; but the remaining reproductive organs are distinctly diphyllobothriidian in their nature. Con- sequently, in order to differentiate more clearly the two families, Ptychoboth- riidae and Diphyllobothriidae, and especially since the genus Haplobothrium presents difficulties in this connection, it is necessary to know the developmen- tal relationships between the uterine duct and the uterus-sac in those genera in which they appear. Up to the present no adequate descriptions of the latter have been published, so that here will be given the observations on the development of the uterus to which reference was made above (p. 16), where the conditions in Haplobothrium and Marsipometra were discussed. In Bothriocephalus scorpii the liunen of the uterus-sac appears suddenly and with a diameter of 90^, the rudiment ahead showing as yet no signs of forming a cavity. This enlargement is situated at first, however, in the cortical parenchyma and among the longitudinal muscles, only the inner tip of the 94 ILLINOIS BIOLOGICAL MONOGRAPHS [382 Structure in transections going into the medulla. Just within the inner trans- verse muscles this inner portion of the sac is joined by the uterine duct which with a diameter of 30/i elsewhere is here only 8)u in diameter. Furthermore, in the genital rudiment of the next proglottis ahead there is a distinct demarca- tion between the aggregagion of nuclei that will form the sac and the axial rudiment of the uterine duct. The same separation of sac and duct with the narrowing of the latter just before entering the former is present in the follow- ing segments even where the first eggs are to be seen in the lumen. Thus the eggs must have passed this narrowed region which is a great deal smaller than their diameters. Still farther back where the lumen is about 165^ in diameter there can be seen not only the situation of the sac in the cortex and among the longitudinal m-uscles, projecting as yet only a short distance into the medulla — altho here the bundles of muscles are deflected peripherally — but also the separation of the two parts by a narrow neck only 10^ in diameter. B. cuspido tus shows the same distinct separation oi the uterine duct and uterus-sac in the proglottides where there are already a few eggs in the latter. In Clestobothrium crassiceps conditions were found to be quite the same. When the lumen of the sac attains dimensions of about 60 by 35m and is lined with an epitheUum which takes the counterstain more like a cuticula but shows nuclei on its surface towards the lumen, the uterine duct opens into it with a distinct reduction in diameter. The epithelia of the two are, however, quite similar and continuous, the nuclei being located in a similar mamier in both. Proglottides ahead show that the sac is form.ed by an enlargement of the end of the duct, which takes place first in that region passing thru the cortex quite as in Bothriocephalus. Thus it is seen that the uterus sac of this family is quite different from the functional enlargement of the uterus of the Diphyllobothriidae, with the exception of that of Haplobothrium, since at all stages in its development it is sharply separated from the uterine duct. But as it was not so much this exact separation of the two portions as the constant presence of an " Uterushohle " in this family and its absence in the other, where the " Rosettenf orm " is more commion, that was emphasized by Llihe, and since the structure in Haplo- bothrium is distinctly ptychobothriidian in character, the functional enlarge- ment of the uterus cannot now be considered to be of such systematic impor- tance as was formerly believed. PTYCHOBOTHRIINAE Liihe 1899 Scolex with two surficial sucking grooves, which may be modified by con- siderable growth together of their free edges. Genital openings surficial, those of the cirrus and vagina dorsal, that of the uterus ventral and ahead of the other two. Vas deferens strongly coiled, dorsal. Ovary ventral; shell-gland dorsal. Vitelline follicles usually in two lateral fields in the cortical or medullary parenchyma. Testes com.pletely filling the medulla, mostly marginal to the longitudinal nerves which are well towards the median line. Occurrence: Exclusively in fishes. Type genus: Bothriocephalus (Rud.) Liihe. 383] PSEUDOPHYLLIDEA FROM FISHES— COOPER 95 The above diagnosis lacks the words "seldom armed" after "scolex" which appear in Llihe's latest (1910:24) characterization not only of this subfamily but of the family, because they do not appear in his earlier papers, (1899:41 and 1902a :336, respectively) nor does there seem to the writer to be any occasion for their use. BOTHRIOCEPHALUS Rud. 1808, e. p. Liihe 1899, e. p. Taenia (part.) Auctorum Rhytelmitithus (part.) Zeder 1800 Alyselminthus (part.) Zeder 1800 Rhytis (part.) Zeder 1803 Bothriocephalus (part.) Rudolphi 1809 Bothriocephalus (part.) Rudolphi 1819 Dibothrius (part.) Rudolphi 1819 Bothriocephalus (part.) Leuckart 1819 Bothriocephalus (part.) Dujardin 1845 Dibothrium (part.) Diesing 1850 Bothriocephalus (part.) Baird 1853 Dibothrium (part.) Molin 1861 Dibothrium (part.) Diesing 1863 Bothriocephalus (part.) Carus 1885 Bothriocephalus (part.) Matz 1892 Bothriocephalus (part.) Ariola 1896 Bothriocephalus s. str. Liihe 1899 Bothriocephalus (part.) Ariola 1900 Bothriocephalus s. str. Braim 1900 Bothriocephalus s. str. Liihe 1910 Scolex elongated, with two only weakly developed sucking grooves. Ex- ternal segmentation well developed ; between two consecutive genital segments there is always present a saw-tooth notching of the lateral border, yet a corres- ponding transverse furrow on both surfaces is sometimes lacking. Vitelline follicles in the cortical parenchyma, continuous from proglottis to proglottis, as are the testes. Receptaculum seminis absent. Beginning of the uterus a winding canal (uterine duct) which opens into a large nearly spherical cavity (uterus-sac or uterus s. str.). Uterus opening approximately median, as is the dorsal genital opening. Type species: Bothriocephalus scorpii (Miiller 1776) 96 ILLINOIS BIOLOGICAL MONOGRAPHS [384 BOTHRIOCEPHALUS SCORPII (MiiUer 1776) [Figs. 21, 22, 55-57, 59-61, 71, 84, 95, 105] 1722 Vermis multimembris rhombi 1776 Taenia scorpii 1780 Taenia scorpii 1780 Taenia scorpii (part.) 1786 Taenia scorpii 1788 Taenia scorpii 1788 Taenia scorpii 1790 Taenia scorpii 1799 Taenia scorpii 1800 Alyselminthus hipunctatus 1802 Taenia punctata 1802 Taenia scorpii 1803 Rhytis hipunctata 1810 Bothriocephaliis piinctatus 1819 Bothriocephaliis punctatus 1819 Bothriocephaliis punctatus 1844 Bothriocephaliis punctatus 1845 Bothriocephalus punctatus 1850 Bothriocephalus punctatus 1850 Dibothrium punctatum 1853 Bothriocephalus punctatus 1855 Dibothrium punctatum 1856 Dibothrium punctatum 1858 Bothriocephalus punctatus 1858 Dibothrium punctatum 1861 Dibothrium punctatum 1863 Dibothrium punctatum 1867 Bothriocephalus punctatus 1878 Bothriocephalus punctatus 1885 Bothriocephalus punctatus 1889 Bothriocephalus punctatus forma bubalidis 1890 Dibothrium punctatum 1891 Bothriocephalus punctatus 1892 Bothriocephalus punctatus 1893 Bothriocephalus punctatus forma molellae 1893 Bothriocephalns punctatus 1898 Dibothrium punctatum 1899 Bothriocephalus bipunctatus 1900 Bothriocephalus punctatus 1900 Bothriocephalus bipunctatus 1902 Bothriocephalus bipunctatus 1902 Bothriocephalus punctatus forma puncta- tus vel typica 1902 Bothriocephalus punctatus forma rhombi 1902 Bothriocephalus punctatus forma cotti- quadricornis [mihi] 1910 Bothriocephalus bipunctatus 1917 Bothriocephalus scorpii Specific diagnosis: With the characters of the genus. Large cestodes, up to 950mm. long by 6mm. wide. Scolex, large, elongate, with prominent Leeuwenhoek 1722 : 402 MuUer 1776 ; :219 Miiller 1780 : 179 Fabricius 1780 : 319 Batsch 1786 ; :235 Miiller 1788 : :5-6 Schrank 1788 : :48 Gmelin 1790 : ;3078 Ratke 1799 : ;68 Zeder 1800 ; :236 Rudolphi 1802 : : 109-110 Bosc 1802 : :307 Zeder 1803 ; :296 Rudolphi 1810 : :50 Rudolphi 1819 :138 Leuckart 1819 :40 Bellingham 1844 :254 Dujardin 1845 :617 van Beneden 1850 :160 Diesing 1850 :593 Baird 1853 :89 Leidy 1855 :444 Leidy 1856 :46 Cobbold 1858 :157 Molin 1858 :134 ^Molin 1861 :235 Diesing 1863 -.240 Olsson 1867 : 14, 55 Linstow 1878 :237 Carus 1885 :120 Loennberg 1889 :32 Linton 1890 :731 Loennberg 1891 :51 Matz 1892 :105 Loennberg 1893 :13 Olsson 1893 :16 Linton 1898 :430 Liihe 1899 :43 Ariola 1900 :394 Braun 1900 :1691 Fuhrmann 1902 :446 Schneider 1902a , : 14 Schneider 1902a :15 Schneider 1903 :75 Liihe 1910 : ;25 Cooper 1917 : ;37 385] PSEUDOPHYLLIDEA FROM FISHES— COOPER 97 terminal disc, widest anteriorly; length 1.0 to 3.5mm., breadth 0,3 to 0.5. Bothria long and narrow, shallow posteriorly. First segments subcimeate with weakly prominent posterior borders, longer than broad. Middle and posterior segments much depressed, former very short and broad, latter rela- tively less so and grouped in twos or threes; lateral borders crenulate. Ripe proglottides 2 to 4mm. wide by 0.2 by 0.8 long. Strobila usually incomplete posteriorly. Cuticula 5/i in thickness. Calcareous bodies 13/z in diameter. Inner longitudinal muscles in fascicles. Six chief longitudinal excretory vessels. Opening of the genital cloaca at the bottom of a dorsal median longitudinal depression running thruout mature segments, on a low papilla in each proglot- tis and half-way between the anterior and posterior borders. Vaginal opening immediately behind that of cirrus. Distinct ductus hermaphroditicus present. Testes subspherical, 35 to lOfi in diameter and 30 to 60 in each segment. Vas deferens a compact mass lateral to cirrus-sac and opposite the uterine tube, 0.18 by 0.10mm. Cirrus-sac at right angles to dorsal surface, 115 by 120 by 75 to 80^, extending only a short distance into the medulla; thick layer of nuclei within its wall. Cirrus proper, not protruded, 65 by 15/z. Ovary compact, tubulolobular, 0.33mm. wide by 0.15 long where uterus- sac is not greatly distended. Isthmus only ventral. Oocapt 35^i in diameter. Vitelline follicles in two lateral weakly united fields on each surface, 350 to 540 in number, 35 to 55^ in diameter; vitelline reservoir small. Shell-gland large, 115/i wide by 85^1 deep, median, close behind cirrus-sac. Uterine duct voluminous on both sides of the median line, closely applied to ovary behind. Uterus-sac spherical to flattened anteroposteriorly, occupies one-sixth of transverse diameter of proglottis, alternating irregularly from side to side, or often quite median. Opening in middle of sac, ventral and well forward, formed by the rupture of a distinct membrane. Eggs, 66 to 80^1 in length by 43 to 45/x in diameter, without opercula, form- ing dark brown maculations in ripe proglottides as they show thru the walls of the uterus-sacs. Habitat: In the intestine of the host. HOST LOCALITY COLLECTOR AUTHORITY Coitus scorpius (ty-pe host) Denmark Muller MiiUer 1788 : 6 Cottus scorpius Gr>'phswald Rudolphi Rudolphi 1819 : 139 Coitus scorpius Ireland Bellingham Bellingham 1844 : 254 Cottus scorpius "Oresund e Berg," Sweden Olsson Olsson 1867 : 55 Coitus scorpius Norway Loennberg Loenberg 1890 : 22 Cottus scorpius Grafvema and Naset, Sea of Bahusia Olsson Olsson 1893 : 16 Cottus scorpius Cottus scorpius Arctic Ocean Linstow 1901 : 281 Gulf of Finland Schneider Schneider 1902 : 15 98 ILLINOIS BIOLOGICAL MONOGRAPHS [336 HOST LOCALITY COLLECTOR AUTHORITY Cotlus scorpius Murman-Kiiste Coll. Zool. Mus. K. Akad. Wiss., Petrograd Linstow 1903 : 19 Cottus scorpius White Sea Danilevskij Linstow 1903 : 49 Cotius scorpius North Sea NicoU NicoU 1907 : 70 Cottus scorpius Firth of Clyde, Millport, Scotland NicoU NicoU 1910 : 355 Cottus bubalis England Cobbold Cobbold 1858 : 157 Cottus bubalis Norway Loennlierg Loennberg 1890 : 22 Cottus bubalis Sweden Loennberg Loennberg 1891 : 51 Cottus bubalis Grafvema and Naset Olsson Olsson 1893 : 16 Cottus bubalis North Sea NicoU NicoU 1907 : 71 Cottus quadricornis Pleuronectes boscius Gulf of Finland Schneider Schneider 1903 : 75 Naples Rudolphi Rudolphi 1819 : 139 Pleuronectes flesus "OresundeBerg" Olsson Ariola 1900 : 396 Pleuronectes maximus Denmark Muller Muller 1788 : 6 Pleuronectes maximus Gr>phswald Rudolphi Rudolphi 1819 : 139 Pleuronectes maximus Ireland Belhngham BeUingham 1844 : 254 Pleuronectes maximus Langrunne, Rennes Dujardin Dujardin 1845 : 618 Pleuronectes rhombus Naples Rudolphi Rudolphi 1819 : 139 Pleuronectes rhombus Ireland Drummond BeUingham 1844 : 254 Pleuronectes solea Kais.-Konig. Leuckart 1819 :40 Nat'l Kab. Torpedo ocellata Naples Rudolphi Rudolphi 1819 : 139 Torpedo oculata Cadus aeglifinus Volz Volz 1900 : 55 Arctic Ocean Linstow 1901 : 281 Gadus minutus Naples Rudolphi Rudolphi 1819 : 139 Arnoglossus boscii Naples Rudolphi Ariola 1900 : 396 Arnoglossus pegosa Ariminus Rudolphi Rudolphi 1819 : 139 Arnoglossus solea Trigla adriatica Mus. Vienna Rudolphi 1819 : 139 Hafnia Eschricht Diesing 1850 : 594 Trigla lineata Ireland Drummond Diesing 1850 : 594 Psetta maxima England Siebold Coll., Brit. Mus. Baird 1853 : 89 Platessa plana Pennsylvania Leidy Leidy 1855 : 444 Platessa flesus Platessa passer Rhombus maximus Germany Trieste Liihe 1910 : 25 Stossich 1898 • 116 Italy Molin MoUn 1858 : 134 Rhombus maximus Patavia Molin Molin 1861 : 235 Rhombus maximus "OresundeBerg" Olsson Olsson 1867 : 55 Rhombus maximus Trieste Stossich Cams 1885 : 120 Rhombus maximus Venice Ninni Stossich 1890 : 7 Hhnmhu^ tnaximti^ Wamemiinde Matz 1892 : 105 X\/H/ritK/HJ //* t*»V fr /f US'** Rhombus maximus Rossitten, Cranz, Muehling 1898 : 36 A^ftviitty tto //n*«v * f /t **o Memel RhofKhu^ maximus Trieste Genova Stossich Ariola 1898 : 116 Rhombus maximus Parona and 1900 : 395 Ariola Rhombus maximus Trieste Stossich Stossich 1901 : 97 387] PSEUDOPHYLLIDEA FROM FISHES— COOPER 99 HOST LOACLITY COLLECTOR -AUTHORITY Rhombus maximus Gulf of Finland Schneider Schneider 1902 : l.S Rhombus maximus North Sea Nicoll Nicoll 1907 : 72 Rhombus barbue Volz Olsson Volz Olsson 1900 ■ 55 Rhombus laevis "OresundeBerg" 1867 : 55 Rhombus laevis Grafvema and Naset Olsson Olsson 1893 : 16 Rhombus maeoticus Odessa Nordmann Linstow 1901 : 281 Lophopselta maculaia Martha's Vine- yard, Mass. Linton Linton 1890 : 732 Bolhus vicculatus Woods Hole Linton Linton 1898 : 430 Hemitripterus americana U. S. Nat. Mus. U. S. Nat. Mus. Linton Linton 1898 : 430 Eemitripterus americana Casco Bay, 1898 : 430 Maine Linton 1898 : 430 Hemitripterus americana Woods Hole U. S. Nat. Mus. Limanda ferruginea Block Id. U. S. Fish Com. Linton 1898 : 430 Limanda ferruginea Woods Hole Linton Linton 1901 : 485 Labrus maculatus "OresundeBerg" Olsson Ariola 1900 : 396 Motella mustela Mus. Vienna Ariola 1900 : 396 Mtdlus barbatus Genova Parona Ariola 1900 : 396 Solea monochii Mus. Vienna Ariola 1900 : 396 Acipenser rut hen us Volz Volz Linton Volz Volz Linton 1900 : 55 Scorpaena porcus 1900 : 55 Paralichthys oblongus Woods Hole 1901 : 484 Lota vulgaris Dvina-Fluss Danilevskij Linstow 1903 : 19 Raja clavata Black Sea Pilat Pilat 1906 : 191 Anguilla vulgaris River Dee, Scotland Scott Scott 1909 : 79 Decapterus ptmctatus Woods Hole Sumner, 1913 : 586 Region Osburn and Cole Hippoglossus hippoglossus Woods Hole Sumner, 1913 : 586 Region Osburn and Cole Myoxocephalus aeneus Woods Hole Sumner, 1913 : 586 Region Osburn and Cole Myoxocephalus octodecim- Woods Hole Region Sumner, Osburn 1913 : 586 spinosus and Cole Palinurichthys perciformis Woods Hole Sumner, 1913 : 586 Region Osburn and Cole Paralichthys dentaius Woods Hole Region Sumner, Osburn 1913 : 586 and Cole Pseudopleuronectes ameri- Woods Hole Sumner, 1913 : 586 canus Region Osburn and Cole 100 ILLINOIS BIOLOGICAL MONOGRAPHS [388 HOST LOCALITY COLLECTOR AUTHORITY Sfntnhpr ^rnnibpT Woods Hole Sumner, 1913 : 586 Region Osbum and Cole Trachurops crumenophthal- mus Woods Sumner, 1913 : 586 Regioa Osbum and Cole Urophycis chiiss Woods Hole Sumner, 1913 : 586 Region Osburn and Cole Hetnitripterus americanus Passamaquoddy A. R. Cooper Cooper (the present Bay, New Bruns- paper) wick Hemitripterits americanus Brandy Cove, A. R. Cooper Cooper (the present St. Croix R., paper) New Brunswick Eemiiripterus americanus Woods Hole V. N. Edwards Cooper (the present paper) ? Myoxocephalus aeneus Woods Hole V. N. Edwards Cooper (the present paper) ? Myoxocephalus groelandi- Woods Hole V. N. Edwards Cooper (the present cus paper) Most of the specimens studied ranged in length from 50 to 240mm., but none of them were considered to be complete posteriorly. The smallest measured 28mm. in length and the largest 677mm. The scolex assumes a variety of forms in preserved material, but agrees in general with the descriptions of that of B. scorpii given by all the authors from the time of Rudolphi (1810: 51). Its commonest shape is shown in figures 21 and 22 where it is seen to be quite elongated, somewhat broader and truncated anteriorly and narrow posteriorly. The anterior portion is in reality in the form of a low pyramid, comparable internally as well as externally with the terminal disc of the Tri- aenophorinae. Its base is deeply indented dorsoventrally, that is opposite the bothria, but rounded laterally. The whole scolex is broadest at about its middle and narrowest at its posterior end. A portion of the latter is here con- sidered to be the beginnings of the first segment on account of its being con- stantly set off from the rest of the scolex ahead by a more or less definite groove. The bothrium is in the form of an elongated V, being ordinarily mdest and deepest just behind the terminal disc and much narrower and shallower pos- teriorly where it is not bounded by a definite wall but spreads out on the base of the scolex. In many specimens, however, the scolex is so contracted and the walls of the bothrium so protruded that the latter shows its greatest depth at the middle of the scolex. In lateral view (Fig. 22) the scolex is more nearly oval in outhne since it is a Uttle wider towards the base. From this fact it is conceivable that Midler's (1788, Fig. 7) showing a more "orbicular" scolex in B. scorpii in lateral view may be explained by supposing that he was dealing with a much contracted specimen, altho in justice to the other side of the question, it must be said that the first segments in his figure are by no means contracted. It will be noticed that the figures of the scolex given here agree 389] PSEUDOPHYLLIDEA FROM FISHES— COOPER 101 very closely with that of Scott (1909, Fig. 3, PL V). However, from the fact that he records B. scorpii as having been found in Anguilla vulgaris, it is quite possible that he had in reality B. davkeps (Goeze) which has been found only in eels up to the present, so far as the writer is aware. Segmentation begins immediately behind the scolex, so that there is no true neck. The base of the scolex, nevertheless, has the appearance of a very short neck region from which the foremost segments are cut off as soon as they form. Such in fact is considered to be the case. The anterior part of the strobila on the other hand serves the purpose of a neck in that it shows a divi- sion into subsegments in a manner to be presently described. As regards the habit of the whole strobila and the general shape of the segments, Rudolphi's (1810:51) description of the species is so applicable to this form that it is given verbatim : "Collum nullum. Corpus planum, margine crenato. Artiaili cdipitiproxr mi plerumque longissimi, angustissimi, subcuneati, margine postico untrinque parum exstante, saepe tamen, praesertim post mortem, contracti, ut reliquis vix longiores appareant. Articuli insequentes anticis breviores et sensim latiores; postici subaequales, fere quadra ti, ut plurimum latiores quam longi, interdum quasi ex duobus tribusve confusis compositi, satis magni, margine obtusiusculo hinc inde inciso. Articulus ultimus obtusus. Lima utrinque longitudinalis articulos majores percurrit. Inter utramque faeturae apparatus." Leidy (1855:444) described the strobila of the B. scorpii which he found in Platesa plana as follows: "Neck none. Anterior segments cuneate or tri- angular; posterior ones quadrate; each \nth an appearance of three subdivisions, with the subsegm.ents having a pair of generative apertures, in the course of a longitudinally depressed dark colored line, passing the length of the body." Cobbold (1858:157) said of individuals from Cottus huhalis: "Toward the lower part of the so-called neck, the joints exhibited at the lateral margins indications of division, which became gradually more defined towards the tail. " In the same connection Krabbe (1865:37) stated that, according to Eschricht, "Pen- dant leur developpement ulterieur, 1' augmentation du nombre des articles n'est pas toujours exclusivement due, comme chez les Taenias, a la formation de nouveaux articles engendres par la tete, mais chez quelques especes, telles que les B. dubius, variabilis et fasciahis, [here B. punctatus also] elle est encore produite par la division transversale qui s'opere dans les articles deja formes. " Olsson (1867:55) also referred to multiphcation of segments by transverse division of older ones. Loennberg (1891 :52) denied this statement of Olsson's, but, as pointed out below, the negation is applicable to the posterior mature seg- ments of this form at least, not to the middle segments referred to by the latter. Linton (1890:773) said "Secondary segments appear at about the twelfth segment from the head. These are formed by a division of each segment into two by means of a median transverse line. This is repeated far- ther back in much the same mamier as described under D. nticrocephalum." In this form such subdivision of segments to form daughter segments occurs 102 ILLINOIS BIOLOGICAL MONOGRAPHS [390 all along the strobila from close behind the scolex to well into the region showing the median row of reproductive rudiments, and in such a manner that, in the anterior part of the strobila at least, what is considered to be a primary seg- ment, situated between the most prominent transverse furrows, becomes sub- divided into 2, 4, 8, 16 and finally 32 divisions, each of the latter accommoda- ting two reproductive rudiments. But it must be emphasized that this method of formation of new segments is not strictly followed out, since as it passes backward in development, the primary segment does not always contain 64 genital rudiments. In the first place, some secondary or even tertiary trans- verse furrows become almost as prominent as the primary ones, and secondly, there is at the same time considerable further subdivision not only of the peri- pheral tissues but especially of the rudiments themselves. Close behind the scolex the primary segments are very short (Fig. 55), the first six to ten being divided only into two subdivisions in strobilae of moderate size, but into three or four subdivisions in the largest chains. Farther back this pro- cess of segmentation takes place gradually; but division is usually seen to occur more readily and quickly in the anterior part of the primary segment or of its major subdivisions, i.e., secondary or tertiary, than in its posterior part — occasionally however the reverse being the case. Thus in general there is a sort of dominance of the anterior end of the segment, which one might call a zooid in the sense in which Child uses the word, over its posterior end as regards metamerism. While this method of formation of segments is further obscured by the fact that often one sees intercalated among primary segments, shoeing these features well, others which seem to lag behind in division and are hence younger, and that in much elongated strobilas it is still more difijcult to distinguish between primary and secondary transverse furrows, owing to their being quite smoothed out especially medially, the whole plan is sufficiently clear to warrant its being described with the definiteness here given. Figures 56 and 57 will give a better idea perhaps of the whole method of segmentation than this description. While in figure 55 the primary seg- ments are indicated by asterisks, in figures 56 and 57 the whole drawing is in each case that of a prim.ary segment. Under the heading of the reproductive system below it will be seen that in the mature portion of the strobila the most prominent transverse furrows are described as coming approximately every eighth or sixteenth genital segment. This is due to the fact that the secondary and tertiary furrows, respectively those dividing the primary segments into two then four parts, become quite as pronounced as the primary ones, thus making it very difficult to follow this plan of segmentation beyond the region of differentiation of the genital rudiments. At least three prominent longitudinal grooves run thruout the median and posterior portions of the strobila on each surface, even cutting thru the posterior borders in many places. Their course is not regular and they are accompanied by numerous other shorter and m.ore irregular grooves, some of which, but not all, are due simply to lateral contraction of the segments. 391] PSEU DOPEY LLIDEA FROM FISHES— COOPER 103 The following table gives a list of measurements of representative speci- mens in alcohol: Total length in mm. 234 173 130 51 677 *233 *180 Length of scolex 1.20 1.07 0.81 1.14 1.11 5.00 0.85 Breadth of terminal disc 0.30 0.33 0.26 0.33 0.28 0.29 0.27 Breadth at middle 0.35 0.32 0.30 0.37 0.31 0.11 0.22 Breadth at base 0.28 0.27 0.24 0.35 0.26 0.11 0.16 Length of first segment 0.14 0.16 0.09 0.18 0.33 1.83 0.44 Length of posterior segment 0.85 0.46 0.35? 0.57 ? 0.54? 0.81 Breadth of same 1.83 1.12 0.53? 0.92 ? 1.70 0.99 Maximum breadth of strobila 2.50 1.60 1.05 1.57 3.35 2.80 1.51 *Somewhat stretched during fixation. Since L5nnberg (1891:52) described the cuticula of the species there has been no mention of it in the literature, so far as the writer is aware. It was found to be 5/x in thickness and composed of two layers, the outer of which is about two-fifths of the whole thickness and is made up of rather stout, closely set "cirri" which stain much more readily than does the inner more homo- geneous and lighter layer. These cirri seem to he on a distinct membrane since their proximal (central) ends are all even and distinguishable in some places as dark granules. In sections stained more deeply than those which show the inner layer as a single homogeneous stratum, the latter is divided into two layers, the outer of which is less deeply stained than the inner and about one- half as thick or one-fifth of the thickness of the whole cuticula. The wavy nature of the cuticula and the basement membrane is as described by Lonnberg, but in many places the membrane is separated from the cuticular musculature by a very thin clear space barely distinguishable with high powers. The cuticula covering the scolex is about 4^ thick, the difference between it and that over the proglottides being due to a thinner homogeneous stratum. The outer layer of the cuticula is not modified to form spinelets on the posterior borders of the proglottides, nor on the edges of the terminal disc, as in C. crassi- ceps, but the pseudociUa are somewhat longer and relatively stouter on the scolex and anterior segments than elsewhere. The subcuticula, from 25 to 30m in thickness, has the nuclei of its spindle- shaped cells arranged at various levels so that the space between the cuticula and the vitelline folUcles is, excepting for its outer one-third, well filled with them (Fig. 84). The chalk -bodies, described lay Lonnberg, were not studied in living mater- ial; but spherical spaces which were evidently occupied by them before they were dissolved out by the acetic acid of the fixing agent, were found to be more 104 ILLINOIS BIOLOGICAL MONOGRAPHS [392 numerous, as Lonnberg stated, in the cortical than in the medullary paren- chyma. In the scolex, however, they are somewhat more numerous than in the strobila, in both of which locations they attain a diameter of 13^. Lomiberg (1891:53) gave a good description of the musculature of the species, while Lulie ( 1897a :747) referred to that of the posterior border of the proglottis in the discussion of the arrangement of the muscles of the whole order. In addition to corroborating the findings of these authors, it was noticed by the writer that the fibres of the transverse series are mostly con- fined to the very short regions between the sets of reproductive organs and are most numerous just ahead of the prominent segmental furrows mentioned above, this applying to both the inner and outer lots. Towards the median line each layer of longitudinal muscles is about 35ju in thickness and composed of bundles of various sizes, in which the fibres are very closely arranged. The outer longitudinal muscles, the extension of which into the posterior borders of the segments immediately behind the scolex are only wealdy developed, are in the scolex confined almost completely to very thin bands situated close to the cuticular musculature in the edges of the bothria, as described elsewhere by the writer (1914a:92) ioxH. globuliforme. Lonnberg (1891:54) described the nervous system so well that little needs to be added. The foremost four large branches from the brain complex were not found to be relatively as large as those shown in Lonnberg's Figure la, and the commissure appeared to be divided into two, not distinctly separated, frontal strands, the whole depth of which, including the space between them, was not as much as that shown in his Figure Ic. In the strobila the chief nerve strands, each from 15 to 25/i in diameter, are situated towards the ventral side of the medulla and at the junctions of the lateral and median quarters of the latter, as shown in figure 84. The excretory system of B. scorpii was described in detail by Fraipont (1881:8), while Lonnberg (1891:53) added some further notes on its structure, the former, however, working on living material in which the canals are much more readily seen. In good toto preparations the ''canaux descendants" may be easily seen in segments showing the reproductive rudiments as well as farther forward. Owing to a mere accident, temporary preparations showing the details of the reticulum of descending canals in great detail were made by the writer with more or less constant success. When some pieces of a strobila were being transferred from synthetic oil of wintergreen to a slide for the pre- paration of toto mounts by the further addition of xylol-damar, they suddenly became opaque white and remained so for some time after the damar and cover- glass had been added. This opacity was found to be due to air having been drawn into the excretory canals not only thru their cut ends but thru the foramina secundaria. But since the superficial reticulum and all the finer canals were filled with air, nothing of the arrangement of the larger canals could be made out until a short time had elapsed, or until the preparation had been heated slightly. Then the air in the smaller canals became replaced by the xylol-damar, and the larger canals stood out as very distinct silver 393] PSEU DOPEY LLIDEA FROM FISHES— COOPER 105 threads. This sort of preparation is unfortunately not permanent, since after a few minutes all of the canals disappear, excepting the very largest which can still be followed as in ordinary toto mounts. The results of this method of demonstrating the excretory canals are shown in figure 61, a camera lucida drawing made while the canals were disappearing from view. Three of Fraipont's large "canaux descendants" can be seen together with much of the anastomes among them and at least two branches to foramina secundaria. The largest and most median canal has a diameter of 50^. But contrary to what was stated by Fraipont (1881:9,11), only six of these main channels were found close to the ventral layer of longitudinal muscles in the medullary parenchyma, and not six for each surface of the strobila. Lonnberg stated, and correctly too, that their number is very variable as is their size and course, the whole forming a compHcated reticulum showing the typical "island formation." As regards the termination of the excretory vessels at the posterior end of the strobila, the writer confirms Fraipont's (1881:10) statement that: " Chez un sujet qui a deja perdu des proglottis, les gros canaux longitudinaux sont rompus au niveau du bord libre posterieur du dernier seg- ment. Les ims communiquent directement avec I'exterieur, les autres ne sont renfermes et se terminent en cul-de-sac." But no cases were met with in the material at hand in which it could be considered that no segments had been lost. Towards the scolex the six vessels gradually come closer and closer together until in the first segments they may appear for short distances in two sets of three each, dorsoventrally situated; but farther on become lost in their anastomoses. Entering the scolex there may be seen four, three, or two main canals, but they cannot be followed as such thru many sections, since they soon break up into the reticulum mentioned by Fraipont as ramifying thruout the scolex. Of the generative organs the earliest writers were able to discern only the external openings ("oscula") and the uteri which, showing their contained, dark brown eggs thru the body wall as a longitudinal series of dark punctations, gave origin to the specific names of Zeder (1800) and Rudolphi (1802 and 1810). Concerning these characters Miiller (1788:6) wrote as follows: "Margines corporis depressi intersectione articulorum crenati apparent; oscula in anterioribus articulis nulla adsunt, in posterioribus vera altera in pagina port in macula albida nigricantes, in altera papilla alba subelevata, punctaque seu globuli utrinque dispalati, qui ovida. Oscula seu pori non seriem rectam in corpore. Taeniae sed hinc et illinc divergentem constituunt, alterum in centro articuU, alterum in intersectione constituum. Articuli postici reliquis latiores punctis utrinque dispersis medio autem coacer- vatis papillullamque exhibentibus repleti sunt; horum coacervatio oculo nudo punctum centri nigrum ofifert, armatus vero ovula seu globulos e membrana ovata pellucida punctulis nigricantibus impleta constantes discernit. " Rudolphi (1810:50) described them in these words: "Singuli enim articuli in superficie dorsali nodulum orbicularem, simpUcem vel duplicem, subelevatum, vel albidum vel fuscescentem aut nigrescentem 106 ILLINOIS BIOLOGICAL MONOGRAPHS [394 exhibent ; in superficie autem ventrali nodulus simplex vel duplex, pariter, sed minus, exstans, quasi perforatus videtur; corporeque pellucido nodulis illis linea corporis media, plerumque tamen irregularis oritur. Noduli aperti ovaria sistunt, ovisque ellipticis mediocribus referti sunt, haec etiam saepe circa eosdem effusa sunt. " From these descriptions it is to be seen that while Miiller made correct observations concerning the relations between the positions of the genital openings and the transverse furrows mentioned above, Rudolphi considered the ventral surface to be that on which the openings of the cirrus and vagina are situated and the dorsal that on which the uterus opens to the exterior. Van Beneden (1850) seems to have been the first writer to describe the anatomy, vnih however some errors of interpretation as pointed out by Lonn- berg (1891). After Lonnberg's the best and practically the only description of the genitalia was given by Matz (1892:105), Ariola (1900:394) and Luhe (1910:25) obviously copying in part at least from him. The earliest traces of the reproductive rudiments appear in toto mounts about 35 to 40mm. from the tip of the scolex. From this region backwards they increase in size, but so slowly that in large strobilas there may be an inter- vening stretch of at least 225mm. before the genital sinus appears. Then the rudiments differentiate very quickly, the first eggs appearing in the uterus- sac about 2mm. farther on in one toto mount made. In the largest strobila at hand the first genital sinuses were seen, when the worm was examined in alcohol, about 375mm. from the tip of the scolex, and the first traces of eggs showed thru the ventral body wall about 20mm. farther on. Van Beneden (1850:162) was the first to mention the relations between the external segments and the sets of reproductive organs. He said: "Dans chaque anneau, il y a deux ou trois appareils males et femelles complets; je pense que ces anneaux se divisent encore plus tard, de maniere a n'avoir plus qu' un appareil dans chaque animal," [here "animal" is evidently a misprint for "anneau"]; and further in his footnote referring to the superscript after "complets": "J'ai vu des anneaux qui en contenaient jusqu'a six." In his figure 4, PI. XXI, he showed four parts of the strobila containing evidently three or four sets of reproductive organs in each segment, with the latter sub- dividing so that two sets appeared in each subsegment in the fourth part of the figure. Leidy described the posterior segments of B. scorpii as " ... quadrate ; each with an appearance of three subdivisions, with the subsegments having a pair of generative apertures, in the course of a longitudinally depressed, dark colored line, passing the length of the body." Linton (1890:733) re- ferred to "the phenomenon which the posterior segments present of being welded together in groups of three or four, an appearance which is quite char- acteristic of the posterior segments and which has been alluded to in various descriptions of the species," while further, in connection with the apertures of the reproductive organs: "In the middle of the strobila there sometimes appear to be as many as four or more papillae to a single segment;" and with reference to the specimens from Lophopsetta maculata: "... toward the 395] PSEUDOPHYLLIDEA FROM FISHES— COOPER 107 posterior end of the body the adult segments are arranged in groups of from four to six simple segments, as if the latter were partially fused together, which is another characteristic of this species." From these statements and the further fact that the posterior proglottides have been described as trapezoidal (Stossich), quadrate (Rudolphi, Linton), subquadrate (Diesing), or at most, broader than long (Rudolphi) — actually about twice as broad as long from Linton's (1890:732, 734) description — it is evident that the groups of four sets of reproductive organs (much less frequently three, five or six) shown here in figures 59 and 60, and separated from each other by grooves which in al- coholic material appear to be complete, have been considered to constitute the ripe proglottides. But, as pointed out by Lonnberg, the lesser transverse fvurrows are only "greater wrinkles or foldings of the surface" and do not cut in deep enough to cause the parts immediately ahead to stand out distinctly like the posterior borders of the proglottides of other species, e.g., C. cras- siceps. Such posterior borders, Vv'ith their accompanying "complete" trans- verse furrows, do occur, however, but only at considerable intervals. One case is shown in figure 95, where it will be noticed there is no such distinct separation of the proglottis from the next one ahead. So far as the writer is aware, this has been pointed out only by Liilie (1910:25) who said: "... in reifen GUederstrecken liegen zwischen zwei vollig durchgehenden, aber auch nur wenig hervortretenden oberfiachUchen Querfurchen in der Kegel 16 sehr kurze Genitalsegmente, die ausserUch voneinander nur durch Zackenbildungen des Seitenrandes gescheiden sind. " In this connection it should also be noted that in his description of Finibriaria fasciolaris (PaUas), a taenioid from various water birds, Wolffhiigel (1900:94) remarked that it is comparable to B. scorpii in that "eine bis ins aussergew^hnhche gestiegerte Anzahl von Geschlechts- apparaten in einer Proglottis sich folge. " In a considerable length of one toto mount of this form there were found ahead of and including the region of differentiation of the reproductive rudi- ments the following consecutive number (from behind forwards) of genital segments between the most pronounced transverse furrows, that is in the primary segments in question: 67, 82, 101, 107, 90, 111, 116, using as the cri- terion of a genital segment, especially ahead of the region of differentiation, the aggregation of nuclei in the median hne which will go to form the central organs and ducts of the sytem. There is, however, much difficulty in making these counts on account of rudimentary or intercalated groups of nuclei which, judging from conditions to be seen in the region of differentiation, may or may not form complete sets of genitalia, and above all of the further subdivision of many of these rudiments, which otherwise proceeds in quite the same man- ner (Fig. 57) as that of the external segments in the anterior part of the strobila. Furthermore, there may often be seen either in the anterior part of the region of differentiation or much farther ahead (Fig. 57) a lateral doubling of the developing genitalia. But since no case was met with of two sets of reproductive organs in a ripe genital segment, it was concluded, especially because of the great infrequency of this duphcation, that one or the other rudi- 108 ILLINOIS BIOLOGICAL MONOGRAPHS [396 ment eventually gets the upper hand and develops at the expense of the other. This is borne out by the fact that in half the cases one rudiment was much larger than the other. The above mentioned groups of rudiments were divided and subdivided by less and less pronounced transverse furrows in the following manner : 67 82 101 43 24 35 47 54 47 24 19 10 14 14 21 18 13 16 16 14 12 12 20 12 15 This continued until eventually the groups of four (or five, rarely six) sets of genitaha of the authors could be made out. Each of these in turn was seen to be divided into two groups of two sets each, so that each lateral crenu- lation corresponded to two (or three) of them, i.e., to the l-32nd division de- scribed above (Fig. 57). In ripe segments this arrangement may obtain or the segment may divide again peripherally, so that each crenulation then corres- ponds with one set of genitalia (Figs. 59 and 60). The latter figures show that "complete" transverse furrows are present between every 8 or 9 (some- times 7, or apparently even 3, 4, 5 or 6!) genital segments. However, other more relaxed strobilas in alcohol showed complete furrows only every 16 to 17 sets of genital segments, there often being a group of 5 instead of the much more common group of four — but in the same neighborhood of the strobila just as complete grooves every 8, 9 or 10 sets. This shows that a grouping of the genital segments into lots of approximately 16, as mentioned by Luhe (1910:25) is so irregular that it can scarcely be said to occur "as a rule, " and that the peculiar method of segmentation of the anterior end of the strobila mentioned above (p. 102) is very difficult to follow with any degree of certainty beyond the region of differentiation of the genital rudiments. The genital sinus is situated on a low papilla (Fig. 59) on the dorsal surface, in the median Une and from one-half to two-thirds of the length of the genital segment from its anterior border, while the uterine opening on the ventral sur- face is located much farther forward, even at the bottom of the groove corres- ponding to the indentation of the edge of the strobila, separating the crenula- tions mentioned above. The sinus itself is circular in outUne and from 40 to 45m in diameter by 15 to 20ju in depth. At its bottom the cirrus and vagina open close together, the latter immediately behind the former, thru a sec- ondary sinus or ductus hermaphroditicus, the walls of which are often found protruding thru the opening of the larger vestibule as if to form part of a func- tional cirrus (Fig. 95). The testes are arranged in two lateral fields in the medullary parenchyma, as pointed out by Lonnberg, and are continuous from segment to segment, altho they show some tendency towards division interproglottidally. The number was given by Matz (1892:106) as about 76, with their size as 40.8^, but here it was found to be from 30 to 60, while their size was 35 to 70/^, 60 being the 397] PSEUDOPHYLLIDEA FROM FISHES—COOPER 109 commonest measurement. The vas deferens, filled with sperms, forms a com- pact mass of coils about 0.18 by 0.10mm. in size, lying irregularly to the right or left of the uterine duct or sUghtly behind the sac and unmediately alongside the cirrus-sac, as shown in Fig. 71. The ductus ejaculatorius portion of the vas deferens within the cirrus-sac, that is, that part occupying the lowermost one-third of the latter, has a diameter of from 4 to 6ju. The middle stretch of the duct often expands to 13^, while the distal part, the cirrus proper, has a maximum length of 65m "with a width of 14^. Matz gave the dimensions of the organ (? the cirrus-sac) as 100 by 50^. The cuticula lining the cirrus is pseudo- iliated on its inner (functionally outer) surface, somewhat as is that on the external surface of the worm. The cirrus-sac is located at right angles to the dorsal surface (Fig. 95) and extends only a short distance into the medulla, as compared to other species. It is ovoid in shape, with the narrower end towards the cloaca, and from 115 to 120/i in length by from 75 to 80m in diameter. Its wall is composed of an inner thick layer of circular muscles and a very thin outer layer, the fibres of which are directed somewhat obUquely, the whole being 8m in thickness. As pointed out by Lonnberg and showTi in figure 95, the organ is pecuHar in that its wall is coated both externally and internally with a thick layer of nuclei which are doubtless mostly myoblastic in their nature. An aggregation of nuclei at the lower pole of the sac, surrounding the vas deferens and continuous with the layer of nuclei on the outside of the pouch, are too numerous to be considered as myoblastic nuclei only. They do not seem to be mentioned either by Lonnberg or Matz. Their arrangement would indicate that they are possibly prostatic in their nature, the whole struc- ture having the appearance of a gland. Retractor muscles of the cirrus proper are scarce. This fact, taken in conjunction with the further fact that the wall of the sac is quite thick and powerful, and that Lonnberg saw only a short thick cirrus when protruded, would lend support to the view that the latter is quite small and not very important from a functional standpoint. Concern- ing copulation in tliis species Lonnberg said: "Es ist daher wahrscheinlich, dass die normale Befruchtung so vor sich geht, dass das Sperma in den Sinus genitahs hinausgepresst wird, und davon entweder passiv durch die Kontrak- tion der Sinus genitalis oder aktiv durch eigene Bewegung in die Vagina gelangt. Sowohl die eine als die andere Weise scheint recht mogUch zu sein, well die Miindung der Vagina ganz neben derjenigen des Penis gelegen ist. " The vagina opens into the ductus hermaphroditicus close behind the cirrus. From there it proceeds close along the cirrus-sac to its lower end, and then turns back to pass over the ovarian isthmus and into the generative space. Its diameter is 13m, while its wall is composed of a cuticula 5m in thickness and a thin layer of circular muscles. Its cuticula is retained until the point of union with the oviduct is reached, where the lumen narrows down suddenly to one- half the former diameter (Fig. 105). The ovary with a width of 0.35mm. and a length of 0.15mni., is somewhat irregularly "biscuit-shaped" (Fig. 71) and situated close to the posterior border of the segment or protruding slightly into the segment behind. It is composed of short tubular lobules of varying 110 ILLINOIS BIOLOGICAL MONOGRAPHS 398] size. In transections it is seen to be "concave towards the surface bearing the genital openings" owing to the fact that the ventrally situated isthmus is quite narrow and thick and consequently not well separated from the lobular wings which extend thruout the whole dorsoventral diameter of the medulla and also somewhat enfold the former posteriorly in the median Une. Ova from the isthmus are ISju in diameter, while their nuclei and nucleoli average, re- spectively, 7 and 3fx. The oocapt is quite muscular, and 35m in diameter. The oviduct proceeds dorsally for a short distance only before it is joined by the vagina at a vestibule into which the oviduct itself opens (Fig. 105) by a narrow slit much as in C. crasskeps. The wall of the duct is composed of an epithelium, in which no cell-boundaries could be made out, but provided with ciUa directed towards the uterus. The oviduct continues dorsally for a short distance with the same structure and diameter, nam.ely ISju, to take on the vitelline duct dorsal to the anterior edge of the isthmus. The vitelUne follicles are arranged in the cortical parenchyma in two lateral fields (Fig. 84) which are, however, slightly connected with each other dorsally and ventrally in the median Kne by a few isolated follicles. No large follicle such as that described by Matz in the neighborhood of the ovary was seen in the material studied. The follicles vary somewhat in size, but average 35 to 55/i in diameter, are very closely crowded together — so as to obscure in toto preparations the testes beneath them — and continuous from proglottis to proglottis. The latter fact makes it difficult, if not somewhat umiecessary, to state the number for each genital segment, but using Matz's m.ethod of multiplying the average number seen in transections by that seen in sagittal sections (here the average of several segments was taken), the number varies from 350 to 540, or 440 on the average. Matz gave 490 as the number. Two main vitelUne ducts proceed from opposite sides of the genital segment and unite in the antero -dorsal portion of the genera- tive space to form a very short common duct which from the amount of yolk it usually contains may act as a vitelline reservoir, altho the same function is shared even to a larger degree by the much coiled and distended proximal portions of the separate ducts. A few cases were met with in which small ducts laden with yolk came from foUicles clearly belonging to the genital seg- ment following. This condition is, however, not surprising in view of the con- tinuous arrangement of the follicles themselves. The diameter of the common duct at its point of union with the oviduct is about S/x. The very voluminous shell-gland is situated dorsal to the ovarian isthmus close behind the cirrus-sac, with a depth of 85m and width of 115)u. The uterine duct is quite capacious since it is composed of many coils extending thruout the whole depth of the medulla immediately ahead of the ovary. Proximally it is lined with a syncitial epithelium which distaUy becomes much attenuated. While it is usually situated in the median Kne it may alternate from right to left as a whole accord- ing as the vas deferens does so on the opposite side of the proglottis, the uterus- sac in such cases remaining in the median line. As above noted, the uterus-sacs were called " ovaries " by the early writers. They were seen thru the body wall to be filled with the characteristic dark brown eggs forming dark patches or 399] PSEUDOPHYLLIDEA FROM FISHES— COOPER 111 punctations, hence the specific names bipunctata and punctata. In this species the uterus-sacs were described by Rudolphi, Leuckart (1819:41), et al, as ar- ranged in a single row, in a double row, or alternating thruout the strobila. They were likewise found to alternate irregularly from side to side (Fig. 60) (e.g., r, 1, 1, r, r, 1, r, 1, 1, r, r, 1, etc.) or to be more medially situated (1, m, 1, m, m, m, m, 1, m, r, r, m, 1, 1, m, m, etc.) but never in two rows, ex- cepting in a very few immature genital segments (Fig. 57), unless the alternating condition in much contracted strobilas is considered as such. While the sac has a diameter of about 0.18mm. when the first eggs appear in its lumen, it may reach a length of 0.35mm. and a transverse diameter of 0.22mm. or about one-sixth of that of the proglottis. The combined uterus-sac and uterine duct may in many cases occupy more than one-third of the width of the segment. The hindermost segments, in which the uterus-sacs may be gorged with eggs to a diameter of 0.65nmi., separate from the chain evidently in pairs, the lines of division taking place at the furrows between the larger crenulations men- tioned above. No detached proglottides were found free, however, in the intes- tine of the host, altho Olsson (1867:55) recorded having found such, while Weinland (1858:9) said that, according to Eschricht, the species "which lives in the sculpin of the Baltic {Cottus scorpius) throws off its whole chain of joints every year and then sends out a new one from the neck. " Like that of the distal portion of the uterine duct the wall of the sac is composed of a much attenuated epithelium from the basement membrane of which the nuclei, separated by wide intervals, project into the lumen like bosses. The uterus- opening is situated ventrally in the middle of the uterus-sac, and with regard to the external segmentation either in the middle of the larger (double) seg- ment or in the groove separating it from the next ahead or behind. Circular in outline and 50m in diameter, it is surrounded by an area of radiating nuclei, thought by Lonnberg to be possibly of the nature of a gland for the secretion of a material of use in the passage of the eggs to the exterior. The actual opening is formed by the rupture of a membrane guarding the outlet, which has a thickness of from 15 to 30/i, (cf. C. crassiceps). The fresh egg is ellipsoidal in shape, dark brown in color, and measures from 66 to 80/i in length by 43 to 45m in transverse diameter. The shell was ob- served to be about 9^ thick in living material and not provided with an oper- culum. No mature eggs showing the six hooks of the oncosphere were met with in fresh material in the field. Nothing was discovered regarding the intermediate host or hosts of this species, not even in the way of food-contents, for the stomachs and intestines of the few sea-ravens examined were all found to be empty. Linton (1890 :732) gave as the food of Lophopsetta maculata and Limanda ferruginea, from which he recorded Dibothrium punctatum Rud., "several species of AnneUds, frag- ments of Squilla, and several specimens of a species of Margarita. " No speci- mens smaller than about 25mm. in length were obtained. According to Udmsky's abstract, Pilat (1906:191), working on B. scorpii from Raja clavata of the Black Sea (the only case of the species having been found in a selachian 1 1 2 ILLINOIS BIO LOGIC A L MONOGRA PHS [400 fish, SO far as the writer is aware) estabhshed the fact "dass seine Larven in den verschiedenen Fischen oder Tieren, welche von Rochen {Raja clavaia) gefressen werden, sich befanden." From the foregoing description it is to be seen that this form is very closely related to the B. scorpii (Miiller) of Europe, altho in many respects it is so different as to almost warrant the erection of a new species to accommodate it. However, on account of the fact that several forms of the European species have been reported, namely, B. scorpii forma biibalidis and forma motellae by Lonnberg (1889:32 and 1893:13) and those from Rhombus maximus and Cottus quadricornis by Schneider (1902a:14 and 1903:75), it is considered that here in America one finds the same species as has been found in Europe. And from a comparison of the measurements given above with those given by Leidy (1855: 444) and Linton (1890:732, 734 and 1897:430), it seems that, little as one can rely on external measurements, they also point to definite differences of habit as this worm is found in different host species on this side of the Atlantic. In the table given below under B. claviceps the important diagnostic data of this form are placed alongside those of the European species for the sake of comparison. The material studied consisted of lots Nos. 191, 196, 197, 198, 287, and 288 of the writer's collection from the intestine of Hemitripterus americanus (Gmelin), No. 17.57 of the Collection of the University of Illinois from the same host, and No. 17.56 of the same collection from Myoxocephalus aeneus (?). DIBOTHRIUM ANGUSTATUM (Rudolphi), species inquirenda Linton (1901a :454, 474) reported this species from Poronotus triacanthus, the butter-fish, and Merluccius bilinearis, the silver hake. Regarding speci- mens from the former he said: "9. Dibothrium angustatum Rudolphi. Intes- tine [PI. XXIV, figs., 269, a, b, c] Thirty-seven young strobiles, August 21, 1899. These agree closely with Diesing's synopsis of this species: 'Head elongate, tetragonal, slender, with oblong lateral bothria; neck very short. First segments elongated, very nar- row, succeeding segments shorter, subquadrate. ' The outhne of the head varies with the state of contraction, but the pre- vailing form is linear, oblong or somewhat clavate. Segments slender, almost cylindrical, slightly enlarged at their posterior ends. Dimensions of an alco- hoHc specimen in millimeters: Length of head, 1.16; breadth, anterior 0.33, greatest breadth 0.33, posterior 0.19. Another: Length of head 1.21, breadth anterior 0.22, greatest breadth 0.26, posterior 0.17. Longest head measured 1.92mm. in length to the first distinct segment. The strobiles are linear or nearly so and measured about 25mm. in length." The species was originally created by Rudolphi (1819:476) to accommodate two specimens from Scorpaena scrofa. The diagnosis he gave, however, applies not only to the anterior end of B. scorpii when much elongated, but also to younger specimens of the same. "Ovaria speciei praecedentis [B. punctatus — mihi] cui haec etiam valde affinis est," from the same description 401] PSEUDOPHYLLIDEA FROM FISHES— COOPER 113 Strengthens this fact, as does Diesing's (1850:594) remark that D. angustatum "specie! praecedentis forsan mera varietas. " Dujardin (1845:614) considered the species to be synonymous with Leuckart's (1819:41) B. affinis which the latter pointed out was "ahnlich dem B. punctalus," only smaller and more elongated. An interesting point that Leuckart brought out, which further strengthens the resemblances to B. scorpH, was that "Em grosseres GHed wechselt gewohnlich mit einem kleineren ab. " "Ovaries" were described as being in one row and nearer the anterior than the posterior edge of the proglot- tis, which with the general characters of the segments and scolex point to B. affinis being merely a variety of B. scorpii. Later Diesing (1863:240) added to the diagnosis: "Aperturae genitalium laterales" — that is surficial, and not lateral in the sense of being marginal, as it is now used. Parona (1887:320) gave a description of the external features which differed little from those al- ready published and even with the four figures accompanying it does not permit one to separate the species from B. scorpii. Matz (1892 :121) merely Hsted the species, while Blanchard (1894:701) included it in his genus Bothriocephalus. Ariola (1896:263, 272, 280) made a few brief statements regarding the form, in which, besides giving the length and breadth of the strobila as 8.5 to 9cm. and 0.9mm. respectively and the dimensions of the eggs as 70 by 51/i, he said that ' 'Osservo che esso tan to per le dimensioni del corpo, quanto per i caratteri dello scoUce nulla ha di comune col B. punctatus, che ha una lunghezza totale di circa 50cm., e quindi constituisce una specie propria, quale appunto I'hanno ritenuta il Rudolphi, il Parona, ed altri elmintologi. " He placed the species (p. 280) among those of the genus Bothriocephalus Rud. with dorsoventral bothria, in his classification of the family " BothriocephaUdae s. str. " Stossich (1898 :1 16) reported the species from Scorpaena porous at Trieste, but added nothing of diagnostic value, while Ariola (1900:419) continued to hold his former opinions concerning the form: "E con cio cade il dubbio di Diesing e di Carus, che cioe il B. angustatus possa riguardarsi come una varieta del Botriocephalo puntato, il quale ultimo ne e assai lontano, oltre che per notevoli differenze di tutto il corpo, per i botridii dorsoventraU. " Linton's report of the species has been referred to; and finally Shipley recognized the species in "Numerous frag- ments taken from the intestine of the salmon, Salmo solar. " Thus it is evident that in the hterature there are not sufficient data to enable one to state whether this form is a separate species or not, but much that points to its being only a variety of the quite variable B. scorpii. Nor was the writer lead to any conclusions by an examination of the material which Linton (1901:474) described from Merlmcius hilinearis, contained in No. 6646, U. S. N. M. It was found to be very fragmentary and immature, but on the whole to suggest B. scorpii in miniature. A toto preparation of one of the widest pieces showed no traces of the reproductive rudiments, but six chief excretory vessels, arranged quite like those in B. scorpii, the median pair being the largest, and all of them quite straight as from pronounced elongation of the whole stretch of segments. On the other hand, the long narrow condition of the scolex seemed to be persistent in the material; but, since no strobilas of B. 114 ILLINOIS BIOLOGICAL MONOGRAPHS [402 scorpii nearly so small were at hand for study, the writer cannot say that such characters do not exist in the latter. On the whole it seems best to consider B. angustatus a species inquirenda until more and better material can be studied and comparisons made between the form that appears here in America and that which is found in Europe. BOTHRIOCEPHALUS CLAVICEPS (Goeze 1782) [Figs. 19, 20, 23, 72, 85, 96] 1722 Vermis multimembris Leeuwenhoek 1722 : 490 1780 Taenia anguillae (part.) MuUer 1780 : 208 1782 Taenia claviceps Goeze 1782 : 414 1786 Taenia claviceps Batsch 1786 : 211 1786 Taenia anguillae Batsch 1786 : 233 1790 Taenia anguillae Gmelin 1790 : 3078 1790 Taenia claviceps Schrank 1790 : 46 1800 Rhytelminthus anguillae Zeder 1800 : 215 1801 Taenia claviceps Rudolph! 1801 : 103 1802 Taenia anguillae Bosc 1802 : 307 1803 Rhytis claviceps Zeder 1803 : 293 1810 Bothriocephalus claviceps Rudolphi 1810 : 37 1816 Bothrioc. claviceps Lamarck 1816 : 582 1819 Bothrioc. claviceps Rudolphi 1819 : 136, 472 1819 Bothrioc. claviceps Leuckart 1819 : 49 1824 Bothrioc. claviceps Nitzsch 1824 : 97 1844 Bothrioc. claviceps Belilngham 1844 : 251 1845 Bothrioc claviceps Dujardin 1845 : 618 1848 Bothrioc. claviceps Siebold 1848 : 147 1850 Dihothrium claviceps Diesing 1850 : 589 1853 Bothrioc. claviceps Baird 1853 : 89 1854 Dibothrium claviceps Diesing 1854 : 578 1859 Dibothrium claviceps Polonio 1859 : 225 1859 Dibothrium claviceps Molin 1859 : 8 1863 Dibothrium claviceps Diesing 1863 : 241 1867 Bothrioc. claviceps Olsson 1867 : 56 1885 Bothrioc. claviceps Carus 1885 : 120 1892 Bothrioc. claviceps Matz 1892 : 108 1893 Bothrioc. claviceps Olsson 1893 : 16-17 1896 Bothrioc. claviceps Ariola 1896 : 280 1899 Bothrioc. claviceps Liihe 1899 : 43 1900 Bothrioc. claviceps Ariola 1900 : 393 1902 Bothrioc. claviceps Fuhrmann 1902 : 441, 447 1910 Bothrioc. claviceps Liihe 1910 : 25 403] PSEUDOPHYLLIDEA FROM FISHES— COOPER 115 Specific diagnosis: With the characters of the genus. Large cestodes up to 540mni. long by 2 to 3 wide. Scolex small, elongate, but usually found contracted to an almost spherical shape; 0.5 to 1.5mm. long by 0.3 to 0.5 wide at the middle. Prominent terminal disc. First segments thick, short and crowded; middle, oblong; posterior, or ripe proglottides, usually 2mm. broad by 0.5 to 0.7 long, often quadrate, arranged in groups of two, between which the transverse furrow is not prominent; other transverse furrows well marked. Cuticula 1 to 2jLi thick. Calcareous bodies very scarce. Main longitudinal muscles not in bundles. Four to six chief longitudinal excretory vessels. No genital papilla; genital cloaca funnel-shaped, midway between anterior and posterior borders of the proglottis. Vagina opens immediately behind the cirrus-sac; no separation between common cloaca and hermaphroditic duct. Testes large, subspherical, averaging 58/i long, 64 wide and 60 deep; 50 to 60 for each proglottis. Coils of vas deferens loose, close behind uterus-sac, 0.35mm. wide by 0.07 long. Cirrus-pouch ellipsoidal, 127 to 145^ deep by 81 to 104 in diameter, thin-walled. Ovary compact, 0.45 to 0.55mm. in width, 0.055 in length and 0.18 in depth; isthmus quite thick, ventral. Oocapt 30/z in diameter. Vitelline folHcles not separated into two fields on either surface, 450 to 720 in number, 45, 80 and 85ju in length, width and depth, respectively; vitelline reservoir large, 175 by 65jli. Shell-gland posterodorsal, alternating irregularly from right to left opposite the vas deferens. Uterine duct quite volummous, be- tween ovary and uterus-sac. Uterus-sac transversely elongate, occupying one-third or more of the transverse diameter of the proglottis, usually larger towards the side bearing the opening; openings form a zig-sag ventral row. Egg, 58 to 63/Li long by 37 to 40 ^vide, without opercula; light in color, show only faintly thru the body-wall. Habitat: In the pyloric portion of the intestine of the host. 116 ILLINOIS BIOLOGICAL MONOGRAPHS [404 HOST LOCALITY COLLECTOR AUTHORITY Anguilla vulgaris Anguilla vulgaris Anguilla vulgaris Leeuwenhoek Diesing Diesing Dujardin 1850 : 590 Zeder 1850 : 590 Rennes Dujardin ^ KJ ^y \J m *lJ ^ -> )» On account of the fact that, according to Rudolphi (1810:31), Miiller (1780:208) ascribed four suckers to his Taenia anguillae, we must look to Goeze (1782:414) for the first accurate description of the species. Under the name "Der Kolbenkopf, Taenia claviceps^' he gave the following diagnosis: 405] PSEUDOPHYLLIDEA FROM FISHES— COOPER 117 "In den Gedarmen eines Aals (Muraena Angiiilla), worin sie der Graf von Borke gefunden. Nach dem Berichte dieses genauen Beobachters 4 Fuss lang. So lang hat er ihn noch in keinem Fische bemerkt. Mit der Lupe lassen sich die beiden langlichten Saugwarzen an dem kolbenartigem Kopfe dieses Wurms besser, als unter dem Komposito bemerken. Sie sind deutlicher gegliedert, als die Bandwurmer aus den Hechten. Die Endphalangen mit vielen kleinen Knotigen angefiillt. Dies die Aggregate von Eiern, deren sie im Wasser, worin sie aufbehalten wurden, eine imzahliche Menge von sich gegeben hatten. Die Glieder kann der Wurm kurz und lang machen, wie aus der Zeichnung erhellet. Dieses ist also, wie der Graf hinzusetzt, eine besondere Art von Taenien. " Gmelin (1790:3078) retained the specific name, anguillae, and described the worm as follows : "T. capite sessili distincto crassiore, articulis oblongis vage torulosis: oscuUs duobus in uno latere. . . . Habitat in anguillae intestinis, ad 4 pedes longa, capite anterius truncato, articulis 8 proximis longiore, articulis circiter600, prioribus subquadratis, latitudinelongitudinem duplo, posterioribus orbicularibus: latitudine longitudinem octuplo superante. " Rudolphi (1810: 38) gave the diagnosis which has been followed by most of the authors since, excepting as regards the position of the bothria : ''Caput polymorphum, articulis aUquot proximis simul sumtis longius, cisque crassius subtetragonum, sub motu saepe utrinque aequale, subovale, plerumque depressum, postice increscens, anticeque non raro margine tumido, untrinque exstante, terminatum. Foveae marginales, sive in latere dextro et sinistro (capitis depressi margine) sitae, oblongae, sub motu variabiles, an- tice plerumque latiores, mox planiusculae, mox magis profundae. Collum nullum. Corporis plani et antrorsum angustissimi articuli varii: primi breves; insequentes longiores, tandem subquadrati, quorum singuli antrorsum angus- tiores, margine postico tumidiusculo, utrinque exstante; articulis ultimus obtusus. Posteriorum margo lateraUs alter media saepe parte foramen dis- tinctum habet. Ovarium in eorundem articulorum media parte sacciforme, saepe maculam rubescentem refert" or in more condensed form (1810:37; 1819:136): "B. capite oblongo, bothriis marginaUbus, coUo nullo, articulis anterioribus brevissimis, mediis oblongis, reliquis subquadratis, margine postico tumido." F. S. Leuckart (1819:49) was unable to find a scolex shaped like that figured by Goeze, but concerning the material he studied he remarked: "Der Kopf lang, grossentheils fast \dereckt, zuweilen auch ganz keulen- formig; bei einigen vorn mehr abgestumpft und der Rand scharf hervorragend. Einige hatten rund um den Kopf iiber den Gruben eine schmale Vertiefung. Glieder alle vie) breiter als lang, sehr schmal, besonders die vorderen, zusam- mengezogen. Ovarien habe ich an keinem Examplare wahrnehmen konnen. " While Nitzsch (1824:97) added, erroneously, "... die Geschlechtmiin- dungen am Seitenrade, " Bellingham (1844:251) merely listed the worm from the eel as above recorded. Dujardin (1845:618) made valuable additions to the descriptions of the species but Diesing (1850:589 and 1863:241), Baird 118 ILLINOIS BIOLOGICAL MONOGRAPHS [406 (1853:89), Olsson (1867:56) and Carus (1885:120) did little more than list the worm in their various works; so that it remained for Matz (1892:108) to give the first comprehensive description of the anatomy, particularly of that of the reproductive organs. Later, apart from reports by various workers of the finding of the species, Olsson (1893:16) noted the infrequent occurrence of the worm in the host, an increase in the number of segments by m^eans of transverse division and the variable form of the scclex; Ariola (1896:268, 272, 273, 280; 1900:393), Liihe (1899:43), Braun (1900:1676) and Fuhrmann (1902: 441, 447) dealt with it from a systematic standpoint; and finally Liihe (1910:25) gave a short diagnosis, m.ostly after jSIatz, in placing it in his latest classifica- tion of the Pseudophyllidea. According to Dujardin this species ranges in length from 25 to 540mm. (Ze- der), but Liihe (1910:25) gave the length, presumably of average individuals, as from 100 to 200mm. with a breadth of about 2mm. While the specim.ens from Anguilla rostrate examined by the writer were quite smiall, fragmentary, immature and much elongated, the longest piece, however, not exceeding 20mm., two from Eupomotis gibhosus, measured 155mm. in length by 2.9 in maximum breadth, and were much contracted, as indicated in figure 19 of the scolex. The latter, according to the authors, varies in preserved material from an almost spherical shape, as mentioned by Goeze and Leuckart and shown in the latter's Fig. 28, Taf. II, to the much elongate form shown in Matz's Fig. 16, Taf. VIII. The tip of the organ may be protruded, flattened or even replaced by a shallow groove which passes from bothrium to bothrium in the sagittal plane, depending on the degree of contraction or relaxation. These dift"erences are brought out here in figure 23, the latter being m.ore like that of Matz. In either case a slight notch is to be seen on the surficial edges of the terminal disc, while the bothria are deeper immediately behind these than poster- iorly where they pass insensibly on to the base of the scolex. The segments have been variously described, but Rudolphi's (1819:136) mention of " ... arti- cuHs anterioribus brevissimis, mediis oblongis, reliquis subquadratis, margine postico tumido" may be considered as indicating their condition in average states of contraction. Matz stated that "Die gleich hinter ihm [the scolex] beginnenden Proglottiden sind, wenn nicht contrahiert, ein Viertel oder ein Fiinftel so lang als der Scolex. Die geschlechtsreifen GUeder sind 2mm. breit und ein halb bis drei Viertel mm. lang; man bemerkt an den GHedern haufig sekundare Teilung, wie bei B. punctatus dadurch wohl bewirkt v.ird, dass der Rand des vorhergehenden iiber das nachfolgende Glied sich nicht erhebt, hochstens deutet eine rings herumgehende Furche die Grenze an, wie es auch bei B. pundaim der Fall ist;" while Liihe (1910:25) said "Die letzten Proglottiden nahezu quadratisch oder sogar langer wie breit. " In the material from Eupomotis gibbosus all of the anterior proglottides were found to be much broader than long, on account of the contraction of the strobilae, while those in detached pieces were from four to five times as broad as long, as shown in figure 72. Apart from Matz, Olsson (1893:16) and Luhe (1910:25) have noted secondary division of segments, or as Olsson stated the case, "Hos denna art 4071 PSEUDOPHYLLIDEA FROM FISHES— COOPER 119 framtrader mycket tydligt och allmant en forokning af lederna genom tvar- delning; man finner nasten hvarje led genom en svagt framtradande tvarlinie deladt i tva lika led, hvartdera med hanliga och honliga organ, om moderledet haft sadana. Afven die konlosa leden visa samma forokningssatt, " which, however, is what Dujardin observed in 1845 when he said that "On remarque en ontre que souvent les articles sont tellement unis deux a deux, que chaque couple parait n'en faire qu'un seul avec une vide transverse et deux appareils genitaux, I'un devant I'autre. " This pairing of the ripe proglottides, also shown here in figure 72, is due to the manner of segmentation which is like that described for B. scorpii, only quite regular, since the reproductive rudi- ments appear relatively farther forward in the strobila and seem to be more sta- ble in development. Concerning this method of increase in the number of segments for this species Liihe (1910:25) said, "Zwei aufeinanderfolgende Genitalsegmente ausserlich haufig nur unvolkommen geschieden, indessen fehlen durchgehende Querfurchen auf den Flachen nie auf so weite Strecken wie bei B. punctalus." On account of the great degree of con- traction of the only two strobilas provided with scolices at hand, the primary segments were not followed with entire satisfaction very far beyond the scolex, but the first two were seen to be divided into four sub- segments each — the first one, shown in figure 19, including the four segments to the * at the side of the figure — with some indication of the next division which would result in eight to the primary segment; the third into eight, and so on. There were indications posteriorly, however, that the primary segment consists of at least 32 genital segments or proglottides, but as in B. scorpii the furrows separating sets of 16, 8 and 4 genitalia become almost as prominent as those between the groups of 32, while even those separating pairs are not as faint as Olsson (1893:16) stated and showed in his Fig. I, Tab. II. At all events it should be emphasized that the furrows are more distinct and con- sequently the proglottides better defined, at least externally, than in B. scorpii. In the material studied the segments quickly broaden behind the scolex to 2mm. at a distance of 20mm. from the latter, and then very gradually attain the maximum width. The following table gives the measurements of the three largest specimens at hand: Length of strobila 155mni. 150mm. 43mm. Maximum breadth 2.9 2.9 2.0 Length of scolex 0.44 0.46 0.46 Breadth of terminal disc 0.22 0.20 0.22 Breadth at niiddle 0.28 0.30 0.33 Depth of terminal disc 0.20 0.20 0.20 Depth at middle 0.26 0.20 0.40 Depth posteriorly 0.27 0.27 0.46 Width of ripe joints 2.0 1.6 Length of ripe joints 0.40 to 0.50 0.4 to 0.6 The cuticula, between only 1 and 2/i in thickness, is difl5cult to distinguish from the finely matted and comparatively dense cuticular musculature. The 1 20 ILLINOIS BIO LOGIC A L MONOGRA PHS [408 subcuticula is from 25 to 40^ deep, and the nuclei of its cells are confined to their central halves. No calcareous bodies were seen in the rather fine- meshed parenchyma, altho according to Braun (1896:1262) such were found by Kiichenmeister in this species. The musculature is comparatively weakly developed. The frontal fibres are fine, scattered thruout the medulla and between the longitudinal fibres; while the same may be said of the sagittal series. The longitudinal fibres are com- paratively few and \videly separated from each other, and as stated by Matz, "are not arranged in bundles. " The chief nerve strands, about \lix in diameter, are situated distinctly dorsal- ly in the medulla and between the lateral quarters of the transverse diameter of the segment. Matz described two main excretory vessels, between which is located the nerve strand, on each side of the body, while Dujardin had previously stated that there were four on each side. In the sections made three were seen to follow a constant course on each side, the nerve strand passing between the more median pair. They are shown in figure 85. The medianmost pair are greatly flattened as they pass close against the uterus-sac somewhat ventrally. Up to the time when Diesing (1863:241) incorrectly described the genital apertures as marginal and alternating, the only references to the reproductive organs of this species were to the uterus-sacs which, being gorged with eggs in the posterior segments, could be seen thru the thin body-wall in the medial line. Cams (1885:120) failed to correct Diesing's error, so that it remained for Matz (1892:109) to give the first and apparently only adequate description of the genitalia, dealing with, however, only the differences between them and those of B. scorpii. The earliest traces of the reproductive rudiments appear about 5mm. from the tip of the scolex while the first eggs in the uterus-sacs come at about 55mm. While the opening of the uterus is well towards the anterior edge of the segment, that of the genital cloaca is midway between the anterior and posterior borders. There is no papilla, the opening being a low funnel-shaped depression in which there is no distinction between the external portion of the cloaca and the hermaphroditic duct. The number of testes as determined directly is from 50 to 69, while their average lengths, breadths and depths are 52 to 63/i, 53 to 70u and 58 to 63/i respectively. The similar data as given by Matz are: number, 56, size 36 to 47)Lt. The vas deferens, about 20;i in diameter, forms a mass of open coils, lateral to the cirrus-pouch and posterior to the uterus-sac, thus occupying the opposite side of the median line from that accommodating the bulk of the uter- ine tube. The whole mass of coils is about 0.35mm. wide and 0.07 long. En- tering the base of the sac with a diameter of 8^, it gradually enlarges until at the cirrus proper it is twice that size. The proximal end of that portion within the pouch, however, is often found enlarged to form a sort of inner semi- nal vesicle. The cirrus-sac itself ranges in length from 127 to 145/i and in maximum diameter from 81 to 104. Matz gave the measurements as 109 by 64/x. In comparison with that of B. scorpii the wall is quite thin and there 409] PSEUDOPHYLLIDEA FROM FISHES— COOPER 121 is no dense layer of nuclei just within it, as indicated in figure 96, while the retractor fibres and small amount of parenchyma are quite loosely arranged. From its opening immediately behind the cirrus-sac, the vagina passes downward and backward among the coils of the uterine duct and joins the oviduct at the dorsal edge of the ovary just a short distance from the oocapt. At the middle of its course it is IS^i in diameter. The ovary is from 0.45 to 0.55rmn. wide, about 55jLt long and 0.18mm. deep, being thus considerably flattened anteroposteriorly. The spherical ova in the isthmus have an average diameter by 13)li. The oocapt is 30/x in diameter, while the oviduct at the point of union with the vagina is often slightly narrower than the vagina, in fact about 10/x. Large right and left vitelline ducts unite in the median Une to form the yolk sac which is 175 by 65m in size. The vitelline follicles with max- imiun lengths, widths and depths of 45, 80 and 85/i, respectively, number from 450 to 720, or on the average 570 for each proglottis, as calculated by Matz's method. They are not separated into two fields on each surface but strongly united arovmd the reproductive apertures, unlike the B. claviceps of Matz, the two ventral fields of which were only weakly united while the dorsal were strongly so. The shell-gland is posterodorsal and on the other side of the median line from the vas deferens. The uterine duct is so voluminous (Fig. 72) that it crowds the uterus-sac and vas deferens to the other side of the median line. It alternates irregularly from right to left, as do the latter. The sac itself is situated in the anterior half of the proglottis where it is somewhat flattened in the longitudinal direction and constantly occupies one-third of the transverse diameter, as shown in Matz's Fig. 15. The openings, each about 30^1 wide, form a zig-zag ventral row, since they are not exactly in the median line but as much as 0.3mm. apart. Apart from being somewhat ragged or villous they are not specially noteworthy. While the eggs of the European form have been given as from 56 to 60/i in length, they were here found to be from 58 to 63/x long by 37 to 40/i wide when measured in the formol in which the specimens were preserved. They are light in color and so do not show thru the body-wall as in B. scorpii. From the above comparison it will be seen that altho the individuals from Eupomotis gibbosus (those from which the data were taken) do not exactly agree with the European species, they are sufficiently close to justify their being considered the same. This was made more certain to the writer by the exam- ination of some fragments of the European form, obtained by Professor Waxd from Dr. O. Fuhrmann of Neuchatel, Svidtzerland, who took them from Anguilla vulgaris in "North Germany." But it should be stated that in the latter material the cirrus-sac and ovary are smaller and the uterus-sac much larger, occupying more than half the diameter of the proglottis in many places; or, the reproductive organs seem to become mature relatively earlier, differences in degree of contraction and relaxation being taken into consideration. The material studied consisted of No. 289 of the writer's collection from Anguilla rostrata, Nos. 17.33 and 16.456 from the collection of the University of Illinois, the former from Eupomotis gibbosus and the latter from Anguilla 122 ILLINOIS BIOLOGICAL MONOGRAPHS [410 vulgaris (North Germany), and No, 17.54 of the same collection from Gas- terosteus bispinosus. The most important data of diagnostic value for the two species, B. scorpii and B. daviceps, are here given in the form of a table for the sake of comparison: B. scorpii B. daviceps European data Data by writer European data Data by writer Length 35-600mm. 677mm. 90-540mm. 155mm. Breadth 1-7 3.35 2-3 2.9 Length of scolex 0.9-3.0 1.2 0.5-1.5 0.46 Breadth of scolex 0.3-1.7 0.35 0.5 0.30 Breadth of posterior segments 4.0 1.8 2 2.0 Length of same 0.22 0.35-0.85 0.5-0.75 0.5 Number of genital seg- ments per external seg- ment 16 8 or 16 Less than in B. scorpii See text Number of longitudinal excretory vessels 6, 8, 12 6 4 6 Number of testes 76 30-60 56 50-60 Diameter of same 40.8m 35-70m 36-47M 60-70m Dimensions of cirrus-sac 100x50m 120x80m 109x64m 145x104m Number of vitelline fol- licles 490 350-540 462 450-720 Size of same 30-40m 35-5Sm Arrangement of same In 2 separate Dorsal fields Dorsal fields Dorsals united; dorsal fields; 2 slightly uni- united; ventral ventrals uni- ventral fields ted; 2 ventral fields weakly ted to same weakly united fields weakly united united degree Dimensions of eggs 50-80x40m 66-80x43 45m 50-60m 58-63x37-40m Arrangement of uteri 1 row, alternat- 1 row, alternat- ing, or 2 rows ing, or 2 rows Diameter uterus : diam. Only small 1 :6 1 :3-l :2 1 :3 segment portion of diameter Longitudinal muscles Close together In bundles Not in bundles Not in bundles 411] PSEUDOPHYLLIDEA FROM FISHES— COOPER 123 BOTHRIOCEPHALUS CUSPID ATUS Cooper 1917 [Figs. 24, 25, 69, 70, 86, 102, 106, 107] 1917 Botkriocephalus cuspidatus Cooper 1917 : 37 Specific diagnosis: With the characters of the genus. Medium sized ces- todes up to ISOrnrn. in length by 2.75 in breadth. Scolex large with very prom- inent terminal disc deeply notched surficially; bothria long and narrow and quite deep posteriorly giving the scolex when viewed laterally the appearance of an arrow-head; 3.3mm. long, 1.0 wide at middle, 2.5 deep posteriorly. First segments subcuneate and circular in transection, with prominent posterior borders; middle gradually broaden until much wider than long; posterior two to four and half times wider than long, or 1 to 2.7mm. in width by 0.8 in length. Posterior end of strobila usually rounded, even when segments have already become detached. Cuticula 3.5/x thick, subcuticula SSfx. No calcareous bodies. Longi- tudinal muscles not in bundles. Four main longitudinal excretory vessels. Genital cloaca median, halfway between anterior and posterior borders of proglottis, deep and funnel-shaped. Vaginal opening close behind that of cirrus; hermaphroditic duct obscure. Testes on each side separated into two fields by the nerve strand, inner much narrower than outer; 50 to 60 in each proglottis; 110, 60 and 80/i in maximum width, length and depth respectively. Vas deferens a large compact mass of coils, elongate and lateral to cirrus-pouch, 0.22mm. long by 0.16 in width, alternates irregularly from right to left. Cirrus- sac very large and thin-walled, 0.25mm. in length (depth) by about 0.20 in diameter. Cirrus protruded, 135m long by 85 in diameter. Ovary compact, with limbs often turned forward, 0.60mm. wide, 0.10 long and 0.13 thick; isthmus thick. Oocapt 20 to 25m in diameter. Vitelline fol- licles 800 to 1000; 70, 50 and 45m in maximum depth, width and length, re- spectively; occupying almost the whole of the cortex, strongly united dorsally and ventrally. Common vitelline duct long and narrow. Uterine duct con- fined to one side of the median line, opposite the cirrus-sac, alternating irregu- larly from side to side. Uterus-sac spherical, occupying one-third of the dia- meter of the proglottis; opening median, close to the anterior edge of the latter. Eggs eUipsoidal, 62 to 66m long by 42 to 45 wide, oncospheres not developed within uteri. Habitat: Ceca and intestine of the host. 124 ILLINOIS BIOLOGICAL MONOGRAPHS •112 HOST LOCALITY COLLECTOR AUTHORITY Stizosledion vitreum (type Flat Rock L., Cooper (the present host) Muskoka, Ont. A. R. Cooper paper) Stizosledion vitreum Giant's Tomb Id., Georgian Bay A. R. Cooper Stizosledion vitreum Sandusky, Ohio H. J. VajiCleave Stizosledion vitreum New Baltimore, Mich. H. B. Ward Stizosledion vitreum Port Clinton, Ohio H. B. Ward Stizosledion vitreum Put-in Bay, Ohio H. B. Ward Stizosledion canadense New Baltimore, Mich. H. B. Ward Stizosledion canadense Kansas City, Mo. H. M. Benedict Hiodon tergisus Havana, 111. H. J. VanCleave Hiodon alosoides Keokuk, Iowa H. B. Ward "Pickerel" Gillett Grove, Iowa G. R. LaRue Percina caprodes Douglas Lake, Mich. G. R. LaRue Perca flavesencs Lakes Kegonsa and Monona, Wis. A. S. Pearse Type specimen: No. 174.2 of the writer's collection. Co-type: No. 174.3 of the same collection, deposited in the collection of the University of Illinois. Type locaUty : Georgian Bay, Lake Huron, off Giant's Tomb Island. So far as the writer has been able to ascertain a description of this species has not yet been published, nor have any bothriocephalid cestodes been reported for Stizostedion vitreum (Mitchill), the common pickerel or wall-eyed pike. In general appearance this species does not arrest attention until a fairly close examination is made, since it is comparatively small and when much relaxed not so very different, at least posteriorly, from some of the species of Proteocephalus, one of which evidently not yet reported, was fotmd associated with it in the same host. It is medium sized, attaining a length of about 180 mm. with a maximum breadth of about 2.75mm. The scolex, on account of its comparatively great depth, is more often seen and much more conspicuous from a lateral view (Fig. 25). Dorsoventrally (Fig. 24) it is long and narrow, showing a terminal disc well set off from the bothria, while laterally it is roughly shaped like an arrow-head, as indicated by the specific name chosen, or somewhat comparable to a flask or vase pro- vided with a low conical lid (the terminal disc). The bothria are long, narrow 413] PSEUDOPHYLLIDEA FROM FISHES— COOPER 125 and elongate oval in lateral view, the greatest depth being near the posterior end. They are separated by a prominent lateral groove on each side, which extends from the anterior edge of the first segment to a dorsoventral grooves just behind the disc. The latter itself is deeply notched dorsally and t^entrally and on account of this groove quite prominent laterally. It is thus seen that the walls of the bothria are comparatively thin. During life they are quite mobile, as might be concluded from their general appearance as well as from their anatomy. Altho the greatest dorsoventral diameter of both the cavity and the walls is in the posterior portion of the bothrium, the more functional portion would seem to be the anterior part immediately behind the notch of the terminal disc. On account of its powerful musculature the disc evidently greatly assists the relatively thicker walls of the bothria in that region in forming a more powerful organ of adhesion than posteriorly. The thin walls behind would, on the other hand, better assist the sagittal musculature in maintaining suction by presenting a greater surface internally for appUcation to the mucosa of the host's intestine. The measurements of the organ are given in the table below. The first segments are subcuneate in outline, and show subdivision in a manner similar to that of B. scorpii. Each primary segment is divided into two segments of the second order (Fig. 24), and farther back these in turn into segments of the third order, and so on, until in the region where the reproduc- tive rudiments appear the primary segment contains thirty-two subsegments. This plan can be followed as in B. scorpii even into the region of differentiation, and indeed much more readily since there is much less irregularity due to inter- calated segments and the further subdivision of others. Furthermore, the same sort of dominance of the anterior end of the primary, secondary, tertiary and quaternary segments — that is, until a group of four reproductive rudiments can be recognized — is seen not only in the size of the subdivisions but especially in the first portion of the region of differentiation, in the rate of differentiation of the common rudiment into the different proximal organs of the reproductive system. As soon, however, as the lumina of the uterus-sacs appear, the plan becomes obscured by the gradual enlargement of the posterior borders of the subsegments, even to those of the fifth order. Thus, in turn there may be seen defined, as one follows them backward, groupings of thirty-two, sixteen, eight, four and two sets of genitaUa. Eventually, at the posterior end of medium sized strobilas and for considerable stretches of the largest these pairs become separated, so that the segment contains only one set of reproductive organs. These hindermost segments are usually about four and a half times as broad as long, but in the most relaxed strobilas they may be only twice as broad as long. The ripe segments in some cases may be so much elongated and constricted at their ends that they appear barrel-shaped. This accounts for the apparent discrepancy in the measurements of the third and fourth specimens of the table below. As shown (Figs. 25, 69) the anterior part of the strobila has a dorsoven- tral diameter almost as great as the transverse one — as a matter of fact some parts of the segments are here almost spherical in cross-section — while the 126 ILLINOIS BIOLOGICAL MONOGRAPHS [414 posterior part is comparatively thick and slightly more convex ventrally than dorsally. The strobila as a whole gradually enlarges from the former to the latter. The following table gives the measurements of six of the largest specimens at hand; all dimensions are given in milhmeters. Length Maximum breadth Breadth half way along the strobila Same immediately behind scolex length of scolex Width posteriorly Width of terminal disc Depth posteriorly Depth of terminal disc Length of first (primary) seg- ment Breadth of same posteriorly Length of ripe seg- ment Breadth of same 178 97 66 53 48 2.74 1.67 1.18 0.72 1.75 2.04 1.25 0.80 0.64 0.55 0.80 0.26 0.18 0.18 0.18 3.35 0.68 1.38 0.83 1.11 0.91 0.26 0.40 0.24 0.37 1.37 0.31 0.42 0.50 0.44 2.44 0.27 0.78 0.38 0.60 1.16 0.22 0.18 0.26 0.30 1.52 0.15 0.27? 0.14 0.31 1.03 0.22 0.37? 0.27 0.33 O.SO 0.87 1.14 1.30 0.40 2.74 1.67 0.80 0.66 0.51 38 1.77 1.34 0.18 1.30 0.37 0.48 0.71 0.31 0.26 0.31 0.61 1.34 The cuticula is very thin, being only 3.5ju in thickness, and with the highest magnifications is resolved into two layers — an outer and an inner, the former about one-half the thickness of the latter, and separated from it by a stratum of granules so minute as to more nearly resemble a membrane. The outer surface of the cuticula is provided with a similar membrane, since there are no cirri or pseudocilia whatsoever. A distinct, tho very thin basement mem- brane, is also to be seen. The two strata of the cuticula seem to be of pretty much the same consistency since they stain about the same, altho the outer constantly appears somewhat darker at first sight on account of the proximity of its two bounding membranes. On the scolex the outer layer is modified into extremely short and fine spinelets, which, while absent from the terminal disc as well as the posterior borders of the segments, are well developed in the bothria and out over the edges of its walls. The subcuticula has the usual reticular appearance, is about 58ai in thick- ness and is provided with numerous comparatively large nuclei (5 to 7.5ai in diameter) distributed equally thruout the tissue, excepting for a stratum about 15m in thickness immediately beneath the cuticula, which is almost constantly free of them. This outer layer is, of course, composed oFthe processes of the 415] PSEUDOPHYLLIDEA FROM FISHES— COOPER 127 syncitial cells below, as well as of other structures lying more deeply in the parenchyma. The parench)ana shows nothing of particular interest excepting for the com- paratively large nuclei of its cells. These are on the average slightly larger than those of the subcuticula, the largest being more constantly about 7.5/i in length. No distinct traces of chalk-bodies were found in sectioned material altho numerous branches of the excretory system resemble such when cut transversely. The musculature of this species is especially well developed. The frontal fibres, altho rather small, are quite numerous, considerably isolated from each other, and extend from the layer of vitelhne glands on one surface to that on the other, everywhere intermingUng with the powerful longitudinal series and being discontinuous only where the largest of the reproductive organs are situated. This applies, however, to mature proglottides, for in the segments immediately behind the scolex they are all but absent. In frontal series they are seen to be contmuous from segment to segment but naturally sUghtly more numerous between the sets of reproductive organs, altho they pass freely among the testes. The same description appHes relatively to the sagittal fibres. Dorsoventrally they intermingle with the vitelline follicles. On the other hand, the longitudinal series presents quite a marked difference. As a matter of fact the pronounced development of these fibres seems to be an im- portant characteristic of the species. They form an area on each surface in cross-section about llSn in thickness and consequently so wide as to restrict the cortical and medullary portions of the parenchyma to two narrow regions, respectively about 75 and 90^i in thickness, as shown in figure 86. The indi- vidual fibres are large (as much as 6.5m in diameter), not united into groups as in B. scorpii and continuous as a whole from joint to joint. On account of their great number and matted appearance in frontal or sagittal series it was found impossible to determine their exact length; but it may be said that in all probability they do not extend individually for more than one or at most two sets of genitaUa along the strobila. Only a weakly developed outer longitudinal series is present, altho the foremost segments have prominent posterior borders, as shown in figure 24. What might at first glance be considered as such, are the very large and numerous longitudinal cuticular fibres forming a compara- tively wide area outside of the subcuticular nuclei in the anterior end of the strobila (Fig. 69). As might be expected from the external appearance of the structure the musculature of the scolex is well developed. Powerful sagittal and radial fibres pass for a short distance behind the terminal disc, which region is there- fore, as noted above, the most functional portion of the bothrium. At the middle of the scolex, however, only the sagittal series is very prominent, while posteriorly at the thickest part of the organ, these too disappear almost entirely. The same diminution of the coronal series from in front backwarks is to be seen, although they are at no level nearly so prominent as the other two sets. As in the strobila the longitudinal fibres are very numerous. They pass uninter- 128 ILLINOIS BIOLOGICAL MONOGRAPHS [416 ruptedly into the base of the scolex as two narrow and very thick, dorso- ventral bundles, somewhat trapezoidal in cross-section, and attach for the most part as far forward as the terminal disc to the walls of the bothria in the usual obHque manner. Only a very few pass on to the tip of the scolex. As might be gathered from the prominence of the edges of the terminal disc, its longi- tudinal arcuate fibres are also very well developed, and obviously essentially related to the greater power of adhesion of the anterior part of the bothrium on each face of the scolex. The nervous system consists of two chief strands, from 30 to 35/i in dia- meter, passing thruout the strobila at the junctions of the lateral three-four- teenths with the median four-sevenths of its transverse diameter. These proportions are, however, in other parts of the strobila (especially anteriorly), or in different strobilae, depending on the degree of contraction, often more nearly 1:3:1. They are moreover usually nearer the dorsal surface of the medulla than the ventral. This is on account of the fact that their course is much interfered with by the testes, both having only a limited space in which to accommodate themselves. They pass into the scolex close to- gether— their axes actually about 70/i apart — and then very gradually diverge, only to start to converge again about two-fifths of the length of the scolex from its tip. After diminishing very sUghtly in diameter each enlarges into an anteriorly truncated ganglion, united with its fellow of the other side by a single commissure which is bent slightly forward into the tip of the terminal disc. The anterolateral edges of the ganglia are at once split into two com- paratively large nerves which pass out directly to the edges of the disc and at right angles to the longitudinal axes of the chief strands. This arrangement gives these anterior connections of the nerve strands a very characteristic appearance both in transverse and frontal sections. The main longitudinal channels of the excretory system are at least four in nmnber, only two of which, however, are at all constant in course, if not in size. These occupy a ventral position thruout the strobila, while the remaining^ vessels, two or more in number and connected by numerous and irregular branches, are more dorsal in position. In the foremost segments the ventral vessels are comparatively close together and situated considerably within the nerve strands, i.e., towards the median line (Fig. 69). There they vary from 13 to 15)Li in diameter, the dorsal vessels having diameters as much as 18/z. As all of these main vessels pass backwards in the strobila they diverge con- siderably, and become more and more irregular in course as the reproductive rudiments are neared. The ventral vessels, however, remain more constant in course. In the anterior part of the proglottis they pass just outside of the vas deferens on one side and the uterine duct on the other, while in the posterior region of the genital segment they skirt the edges of the ovary or in many cases pass beneath them. They may attain a diameter of 40/i. Furthermore, while the dorsal vessels are forming a very open plexus by numerous large transverse connections in the lateral portions of the medulla, the ventral pair give off at right angles to their courses many short lateral branches passing among the 417] PSEUDOPHYLLIDEA FROM FISHES— COOPER 129 testes and other median connections more numerous between the sets of repro- ductive rudiments. In mature proglottides only the more regular ventral vessels can be followed with any degree of satisfaction. As the vessels enter the scolex, the dorsal series soon breaks up into an irregular plexus, consisting of large branches and lacunae, situated more particularly in the large posterior portions of the organ; while the ventral pair quickly diminish in size and regularity of course, but do not lose their identity entirely until at least one-half the length of the bothria is passed. In the youngest strobilas at hand what was considered to be the "end proglottis" showed the excretory system as terminating in an irregular plexus from which numerous foramina secundaria passed to the exterior quite as in Fraipont's (1881, Fig. 8, PL II) view of the conditions in B. scorpii. The genitaha have the general habit of the genus. The common genital opening or cloaca, situated dorsally in the median Hne, is usually about half way between the anterior and posterior borders of the proglottis, while the uterus opening on the ventral surface is quite near the anterior border, so close in fact that in much contracted strobilas it may be all but obscured by the posterior border of the proglottis ahead. UnUke B. scorpii both openings are situated at the bottom of comparatively deep depressions, as shown in figure 102, that of the genital cloaca being usually circular in outline, about 0.10 mm. in diameter and 0.11 in depth. In some proglottides, however, it may be so contracted longitudinally as to present a transverse diameter of 0.45mm., with a length of only 0.04 and a depth of 0.13. The ductus hermaphroditicus or secondary cloaca is very shallow in this species, and only about 55ju in dia- meter. In most of the preparations made it was usually occupied by the tip of the cirrus, when the latter was not extruded, the opening of the vagina form- ing a very narrow crescent-shaped sUt close behind it. In some cases, how- ever, both the cloaca and the ductus were so contracted longitudinally that the tip of the cirrus was found almost inserted into the entrance to the vagina. From this fact, together with the comparatively great depth of the cloaca in such states of contraction, it is conceivable that self -impregnation may take place; but nothing in the nature of a cloacal sphincter to assist in this function is present. The testes are continuous from proglottis to proglottis in two lateral fields separated by the median row of proximal organs of the reproductive system. Since dorsoventrally they occupy almost the whole diameter of the medulla, each is further separated into two more or less irregular fields by the nerve strand. The more median field consists of little more than one longitudinal row of the folUcles. The number of testes is usually from 25 to 30 on each side, with a variation of a few in either direction, thus making the total number from 50 to 60 on the average. They are ellipsoidal in shape with their longest axes transverse to that of the strobila, and attain dimensions of O.UOnim. in width (in the transverse direction), 0.060 in length and 0.080 in depth. On account of their large size, as compared with that of B. scorpii, they are natural- ly much more regularly arranged in the proglottis. 130 ILLINOIS BIOLOGICAL MONOGRAPHS [418 The vas deferens forms a very compact mass of coils lateral to the cirrus- sac and extending from the uterus-sac ahead to the wing of the ovary on that side behind. It alternates irregularly from right to left, as does the greater part of the uterine tube which occupies a similar position on the other side of the cirrus-sac. In states of moderate contraction of the proglottis it is about 0.22mm. in length, 0.16 in width and 0.18 in depth. Immediately within the cirrus-sac the vas deferens continues as a thin- walled seminal reservoir, sUghtly coiled and occupying approximately the ventral one-third of the former. It varies from 35 to 80^ in diameter, but in the sections made it was found to contain only a comparatively small number of spermatozoa. Beyond this receptacle the duct narrows down to about 5/i in diameter and continues as the ductus ejaculatorius with many coils, situated in the proximal one-third of the sac alongside the seminal reservoir even when the cirrus is protruded. This portion of the duct very gradually enlarges as its circular muscle fibres become more numerous and its lining thicker and thicker as it merges into the cuticula of the cirrus proper. The latter is about 5/x in tliickness and deeply "cleft," or, to be more precise, broken up into a great number of coral-like vilK by means of irregular separate pittings reaching ahnost to the base of the tissue. The duct may here (at the middle of the cirrus-sac) attain a diameter of 25/i. The cirrus proper is somewhat conical when protruded (Fig. 102) and has a maximum length and width of 130 and 85/x, respectively. However, on account of the similar structure and large diameter (25m) of that part of the duct still invaginated within the sac one is led to think that the organ may reach a much greater length — with probably a considerably smaller diameter. P rom the tip of the cirrus to the inner end of its duct, where the cleft cuticula stops and which point might well be the functional tip of the organ, it is at least 0.28mm. in length. Thus it would seem that the organ functions as a very efficient and powerful intromittent organ. The cirrus-sac is ovoid in shape and comparatively large, being about 250/i in depth (length of longitudinal axis, which is directed dorsoventraUy), 180ju in length and 210 in width, when the cirrus is not protruded, and thus somewhat flattened in the longitudinal axis of the strobila. Its wall is only about 2.5/x in thickness, and composed of very fine muscular fibres the direction of which was not determined with certainty. The contents of the sac consists of a loose parenchymatous tissue, containing many nuclei and numerous retractor muscle fibres. The nuclei, which are situated close around the duct and are comparatively numerous, are in all probability myoblastic in their nature. The retractor fibres pass obliquely upwards and inwards from all points of the wall to their points of attachment to the cuticula of the cirrus. This attachment is seen very nicely when the cirrus is protruded (Fig. 102) , for then the fibres are much elongated and theycan be followed even to the evaginated cuticula. Their myoblastic nuclei are quite easily distinguished, especially in the everted portion of the cirrus. The cirrus- sacs are all in the median Hne, their longitudinal axes being almost constantly in the median sagittal plane. 419] PSEUDOPHYLLIDEA FROM FISHES— COOPER 131 The vagina opens immediately behind the cirrus at the bottom of the genital cloaca with an aperture which forms an arc of a circle. It passes ven- trally in the median hne close to the posterior wall of the cirrus-sac and then, after taking a few coils on a level with the lower border of the isthmus, it joins the oviduct a short distance from the origin of the latter. Thruout its course it is considerably flattened anteroposteriorly, its dimensions being alongside the cirrus-sac about 46 by 18ju. It is provided with a cuticula, 3/x in thickness and thrown into longitudinal folds. It gradually diminishes in size until a diameter of about 15;u is reached — at the ventral border of the ovary — and then enlarges somev.'hat before joining the oviduct in a dorsoventral transverse plane, but without forming a distinct receptaculum seniinis, altho a consider- able length of this portion of the duct is often found filled with spermatozoa. Unlike that of B. scorpii the ovary of this species is a compact organ, 0.60rrLm. wide, 0.10 long (the wings) and 0.13 deep. The elongated oval shaped wings (Fig. 86), usually directed forwards, since the whole organ is situated right at the posterior border of the proglottis and close against the uterus-sac of the next proglottis, are attached by narrow necks to the somewhat wider and bul- bous isthmus. Ova from the latter are oval in shape, measure about 15 by \2n and have nuclei 6/x in diameter with nucleoli 2.5^. As in B. scorpii the wings occupy the whole of the dorsoventral diameter of the medulla, while the median bulbous portion of the isthmus almost reaches the same level dorsally. The oviduct arises dorsolaterally from the isthmus in the somewhat elongated oocapt which has a diameter of 20 to 25^ and a length of from 25 to 30^. Im- mediately beyond the oocapt it gradually enlarges from a diameter of 7 to 20/1 where it is joined by the vagina only a short distance either to the right or left from its point of origin. At the junction of these two ducts there is only a very small vestibule, as in the foregoing species, into which, nevertheless, the oviduct may be seen to open by a longitudinal slit, and from one corner of which it proceeds with a diameter of 6.5/x. After continuing almost directly dorsally with only a few very open coils it is joined at about the level of the upper edge of the isthmus by the common vitelline duct. Thruout its course the epithelium of the oviduct is poorly provided with ciha and is surrounded by only a comparatively small number of circular muscle fibres. The common vitelline duct has a diam.eter just beyond its point of origin with the oviduct of 25ai or more. It is directed transversely above the generative space from the dorsal edge of one horn of the ovary to about the median line, where the separate vitelline ducts unite. In sections it is usually filled with yolk cells. The vitel- line ducts, themselves, pass laterally close in front of the wings of the ovary, and hence between them and the vas deferens and uterine tube. When empty, they have a minimum diameter of only 3^t. The vitelline foUicles, as shown in figure 86, occupy almost the whole of the cortical parenchyma between the longitudinal muscles and the nuclei of the subcuticular cells. They are ellip- soidal in shape, their longest diameters being directed at right angles to the surface of the strobilia. They are longest near the median line and smallest at the edges of the strobila. In general they may be said to be arranged in two 132 ILLINOIS BIOLOGICAL MONOGRAPHS [420 lateral fields continuous from proglottis to proglottis, but the latter are united dorsally and ventrally between the sets of genitalia by the largest which are somewhat more numerous and irregularly arranged ventrally. The average maximum depth, width and length, of the individual follicles are 70, 50, and 45/i, respectively, while the diameter of the smallest lateral follicles, more nearly spherical in shape, is about 25At. Their number as calculated from sec- tions averages from 800 to 1000 for each set of reproductive organs. The shell-gland is situated dorsally and to one side of the median line, the beginning of the uterine tube occupying the other side of the generative space. The latter is here not so much a space enclosed by the ovaries as the region of union of the proximal portions of the generative ducts. That part of the oviduct with which the cells of the gland are connected is only about 60m in length. Beyond the ootype the oviduct gradually enlarges as it passes to the other side to become the uterine tube. Farther ventrally the comparatively large coils of the uterine duct pass back to the same side again and occupy a space lateral to the cirrus- sac, as mentioned above in connection with the vas deferens. Just beyond the shell-gland, where the syncitial nature of its epithelium can be made out, the oviduct has a diameter of 13/i. The uterus-sac is relatively large in this species, spherical in shape and occupies one-third of the diameter of the proglot- tis anteroposterior^ as well as laterally. This applies to proglottides in mod- erate state of contraction, for in much relaxed ones it is somewhat ellipsoidal in shape with its long axis in the median line. The youngest uterus-sac which was seen to contain eggs in the largest and most relaxed strobila at hand was spherical and had a diameter of 0.15mm., while the largest of the same chain, also spherical, was 0.50mm. in diameter. But even when they appear circular in outline from a superficial view, they are not in reality spherical since they lead off funnel-wise ventrally to the uterus-opening. The superficial aspects of the latter have been already dealt with above, so that it will be necessary to state here only that it has quite the same structure as that of B. scorpii, and that the actual aperture when formed is irregularly circular in outline with a transverse diameter of 60 to 85/i. The wall of the uterus-sac just within the opening is in many cases broken up into numerous processes, evidently cuti- cular in their nature, which protrude thru the aperture. The egg is elUpsoidal in shape during life, and from 62 to 66^ long by 42 to 45m wide. None were found to contain oncospheres, but only masses of cells such as shown in figures 106 and 107, the smaller of which obviously represents an earher stage in the division of the latter. While most of these cells are yolk- cells, the large one shown at one end of figure 106 is the undivided egg. The granules of figure 107 are those resulting from the breaking down of the yolk- cells. Eggs sectioned in the uterus-sac showed similar stages in development and confirmed these statements. These measurements and drawings were made on August 2, 1912, so that it is probable that the development of the oncosphere is completed in autumn. Cohceming the life-history of this species it may be said that many of the earliest formed segments are lost long before they become sexually mature, 421] PSEUDOPHYLLIDEA FROM FISHES—COOPER 133 since most of the youngest strobilas were found lacking the end proglottis. Constrictions at about the middle were present in many of them, as if the length of segments behind that region might be thrown off as a whole. Since, however, this is not a constant feature, it is considered to be due rather to the fixation of a wave of contraction passing over the strobila, such as may be seen in living individuals as well as in plerocercoids of other genera of cestodes, e.g., Scolex polymorphus. From the foregoing description it is to be seen that this species of cestode is new. The specific name, here chosen, has reference to the peculiar shape of the scolex as seen from the side: cuspis, an arrow-head. The material studied consisted of Nos. N.B. 6a, N.B. 6d, N.B. 6g, No. 47, No. 50a, No. 54c and P.B. 2 from Stizostedion vitreum, N.B. 38a, 08107, 08108, 08109 and 08110 from Stizostedion canadense, and Ha 34a and Ha 35a from Hiodon tergisus, in the collection of the University of Illinois; Nos. 398, 423 and 481 from S. vitreum in the collection of Dr. H. J. Van Cleave; Nos. 7b from Fercina caprodes and 421 from a "Pickerel" in the collection of Dr. G. R. LaRue; twelve toto preparations from Perca flavescens in Dr. A. S. Pearse's collection; and Nos. 41, 170, 172, 173, 174, 193 and 194 from S. vitreum in the writer's collection. The material from Perca flavescens was larval, while that from Percina caprodes was mature but of a small size. BOTHRIOCEPHALUS MANUBRIFORMIS (Linton 1889) [Figs. 26, 27, 62, 73, 87, 88, 97] 1889 Dibothrium manubriforme 1890 Dibothrium manubriforme 1898 Dibothrium laciniatum 1898 Dibothrium manubriforme 1899 Bothriocephalus laciniatus 1900 Bothriocephalus manubriformis 1901 Dibrothrium lacinlatutn 1901 Bothriocephalus histiophorus 1902 Bothriocephalus manubriformis Specific diagnosis: With the characters of the genus. Large cestodes up to 220mm. in length by 5mm. in maximum breadth. Scolex large, elongate, with prominent terminal disc deeply notched laterally as well as surficially, constricted posteriorly; length 2 to 3.5mm., depth at middle, 1.0, breadth of disc, 1.0. Bothria long and very narrow posteriorly where the walls are quite thick. First segments cuneate with salient posterior borders which are dis- tinctly emarginate; middle, broadly cuneate, less emarginate; posterior or mature, many times broader than long and closely crowded, 5 by 0.2mm.; gravid proglottides, 2 by 0.4mm. Posterior half to two-thirds of the strobila provided with a median line (the combined uterus-sacs). Cuticula 4.5/x thick. Calcareous bodies large, 18 to 26 by 11 to 15m. Longitudinal muscles well developed, in bundles. Anteriorly four chief ex- cretory vessels. Linton 1889 :456 Linton 1890 :728 Linton 1898 ; :425 Linton 1898 :429 Liihe 1899 :43 Ariola 1900 :410 Linton 1901a :437 Shipley 1901 ; ;209 Porona 1902 :7 134 ILLINOIS BIOLOGICAL MONOGRAPHS [422 Genital cloaca median or slightly displaced towards either side, deep and narrow, separated from hermophroditic duct by a narrow velum, half way between anterior and posterior borders of the proglottis. Vagina opens im- mediately behind cirrus or very slightly to one side. Testes ellipsoidal in shape, 64 to 75/x wide, 45 to 60 long, 64 to 80 deep; 60 to 70 in number, dorsal in the medulla. Vas deferens closely applied to inner end of cirrus pouch, 85/^ long, 175 wide and 400 thick, somewhat crescen- tic in the dorsoventral-transverse plane, opposite the uterus-sac. Cirrus-sac long and cylindrical, 0.50 by 0.14mm., inner haK deflected towards the vas deferens, walls very thick, composed mostly of circular muscles. Cirrus short, usually not extending outside of the proglottis, 30 to 35/z in diameter. Vagina with bulbous sphincter near its opening, 50ju long by 70 in diameter. Ovary irregularly branched but compressed anteroposteriorly, 0.45mm. wide; isthmus only ventral. Oocapt 30/i in diameter. Vitelline follicles extremely numerous, 35^^ long, 60 wide and 85 thick. Vitelline reservoir large, 60^t in diameter. Uterine duct voluminous on both sides of the median line, crowding all other organs. Uterus-sacs alternate irregularly from side to side, each 0.45mm. in diameter, encroach greatly on neighboring segments, with thick musculo-glandular funnel-shaped ventral portion. Apertures form two lines on the ventral surface 1mm. apart. Eggs 58 by 34//, dark brown, showing thru walls ofuterus-sacs. Habitat: Intestine of the host. HOST LOCALITY COLLECTOR AUTHORITY Tetrapterus albidus Woods Hole, Linton Linton 1889 : 458 (type host) Mass. Eistiophorus gladius Newport, R. I. Linton Linton 1890 : 731 Tarpon atlanticns U. S. N. M. Woods Hole, Linton Linton 1898 : 435 Istiophorus nigricans Linton 1901 : 448 i=H. gladius) Mass. Tetrapterus imperator Woods Hole, Linton Linton 1901 : 447 i = T. albidus) Mass. Eistiophorus sp. Indian and Pacific oceans A. Willey Shipley 1901 :209 Tetrapterus belone Portoferrajo, Id. Elba Damiani Parona 1902 : 7 Type specimen: No. 4711, Coll. U. S. National Museum. Co-type: No. 16.461, Collection of the University of Illinois. Type locaUty : " Penekese? " Although this species was first described more or less in detail by Linton (1889:456) and further notes were added by the same worker in the following year (1890:728), the writer feels that there is still much to be learned about it in spite of the fact that Ariola (1900:410) was able to indicate the genus to which it belongs and to correct some errors concerning the arrangement of the 423] PSEUDOPHYLLIDEA FROM FISHES— COOPER 135 bothria in his rather brief description, which is inadequate for diagnostic pur- poses. Consequently an attempt is here made to better define the species so far as can be done with the poorly preserved alcoholic material referred- to immediately above. In general appearance the worm arrests attention on account of the very closely arranged posterior genital segments, which give that part of the stro- bila a transversely plicate aspect. On closer view the anterior segments with their " salient " posterior borders and the characteristic scolex are seen (Figs. 26, 62). The latter was described by Linton as follows: "Head cuneate, tetrangular, truncate in front, tapering posteriorly into a cylindrical neck-like part near posterior, then expanding so that the posterior end of the head resembles one of the anterior segments of the body. The general appearance of the head when viewed laterally [surficially] is there- fore somewhat like a ball-bat, the constricted part representing the handle. Two longitudinal fossae [bothria], laterally placed, extend from the anterior part of the head to the constricted part. Each of the marginal lobes thus form.ed is indented at the anterior extremity by a short but deep [only in much contracted m.aterial] secondary fossa, which together with the two lateral fossae, give the head when viewed in front a four-lobed appearance. The edges of the lobes bordering the lateral fossae [the walls of the bothria] are thin- hpped and flexible; anteriorly there is a transverse elevation forming both a lateral and a marginal rim and making an obtuse angle between the front and the side of the head. " This is the pyramidal or somewhat conical terminal disc, so characteristic of the scolex. (Figs. 26, 27). The walls of the bothria are "thin-lipped and flexible" only when protruded considerably; in moderate states of contraction, that is, nearest to what the WTiter considered to be the probable state of rest, they are comparatively thick and especially so in the posterior half of the scolex where in consequence the bothrium is reduced to a narrow vertical sHt. "The marginal lobes, when at rest, have a rounded outline, fullest in the middle, tapering posteriorly, appressed sUghtly anteri- orly, and raised into two small eminences on each side of the secondary fossae. The head in a marginal view is somewhat flask-shaped. Seen from the front the head is squarish, with the angles rounded and the sides deeply cleft, the clefts rounded, the lateral clefts deeper than the marginal. " As regards the segments Linton in continuation stated that: "Immediately back of the head the segments are very narrow, and for a greater or less dis- tance, depending on the state of contraction, maintain about the same width as the base of the head. In some individuals the small anterior segments con- tinue much farther back from the head than in the one figured. The segments are alternately short and long. This characteristic is quite plainly marked in the segments which immediately foUow the head, is still noticeable on the median segments and also on the posterior ones, but is not so plainly marked on the latter as on the two former. " This is due to the manner of subdirision of the segments which is carried out in the same way as in B. scorpii and B. cuspidatus. It can be followed with certainty, however, only in the " anterior " 136 ILLINOIS BIOLOGICAL MONOGRAPHS [424 and middle portions of the strobila and not posteriorly where the segments are very short and crowded close together longitudinally, even tho the latter may not show the rudiments of the reproductive organs. Figure 62 is an outline of a primary segment, the fifth from the scolex in this case, to show this method of subdivision. Dominance of the anterior over the posterior half of the segment as regards rate of division is well shown; and this is seen to be appUcable also to the subsegments even to those of the fourth order. "In one specimen examined," to continue to quote from Linton, "the first six segments did not show this alternation in size. In the next fourteen seg- ments, however, the alternation was quite evident. " This indicates that he noted the division of the segments into subsegments but did not ascertain the exact manner in which it is carried out. "The small anterior segments are terete, subtriangular in outline, narrow in front, wide behind, the length nearly equal to the greatest breadth." It is rather difficult to say to what segments or subsegments the latter part of this statement refers, since it describes not only what is here considered to be the first primary segment, i.e., the largest segment immediately behind the scolex as shown in the figure 26, but also many of the major subsegments of the following primary segments — not all, however, since as indicated in figure 62, the dominance in division mentioned above renders subsegments of the same developmental value different in size. Furthermore, as regards these anterior segments it must be empha- sized that their prominent or saUent posterior borders are distinctly emarginate, which condition, very obvious in the segments immediately behind the scolex, can be followed back to the region where the segments get very broad and short. Concerning this notching of the posterior border, Linton (1889:458) said: "The segments of the first series are sometimes notched or crenulated on the posterolateral margin, with a single median indentation; in others the edge is but slightly wavy; in others it is nearly entire. " In the material at hand, however, this emargination was found as just described in all of the specimens, altho in much contracted strobilae it is at first sight apparently absent. "The succeeding segments are much broader than long. At the widest part the ratio of the breadth to the length is as much as fourteen to one. As the seg- ments increase in width they become much crowded together and thickened. . . . The crowding together of the median segments is not due to contraction, but seems to be a permanent characteristic of the species. " Concerning the posterior segments Linton noted further (1890:729) that in the dead specimen taken from Histiophorus gladius, actually No. 16.461 referred to above, "The margins of the strobila are apparently entire. The segments are very short, with their posterior edges sUghtly wavy on the median segments, thus suggesting those of D. plicatum. The posterior edges of the median seg- ments are crowded together like the edges of the leaves of a book about 0.2mm. apart. Near the posterior end they are not so closely crowded, being about 0.4mm. apart." (Fig. 73). Confirmatory frontal sections showed that this " entire " nature of the edge of the strobila is in reality due to partial decompo- sition; yet at the same time the surficial portions of the posterior borders of 425] PSEUDOPHYLLIDEA FROM FISHES— COOPER 137 the segments did not seem to be much affected. In addition it should be noted that besides being "not so closely crowded" the segments at the extreme posterior end of this strobila are relatively much narrower, as a matter of fact, only two-fifths as wide as the widest part of the strobila. This seems to be quite comparable to the elongation of the posterior end of Schistocephalus when it reaches the final host and matures. Another important characteristic, which should be menrioned here in deal- ing with the external features, is that "In alcoholic specimens a dark median line will be noticed extending from the posterior end to the middle or anterior third of the strobila. This is due to the centrally situated ovaries [uterus- sacs] which are crowded with eggs;" while "a median furrow on one of the lateral [surficial] faces of the body begins toward the anterior and becomes punctate towards the posterior region, where the minute lateral genital aper- tures become visible in a zig-zag row. " The following table gives comparative measurements of several strobilas, the first columns being the data given by Linton: 1 2 3 4711, U.S.N.M. Specimen Data by Linton Data by the writer 16.461 Length of strobila 133mm. 3.50 1.00 140mm. 3.00 0.90 0.80 20mm. 2.10 0.80 0.60 115mm. 2;2.5;1.5 1;1;1.2 220mm. Length of scolex Breadth of terminal disc Breadth just behind terminal disc 2.0 0.94 Breadth at middle of scolex 0.64 0.44 0.81 0.89 1.05 0.58 0.63 0.39 0.54 0.89 Breadth at constriction 0.21 0.31 Breadth posteriorly Depth of terminal disc Depth at middle 0.90 Depth at constriction Depth posteriorly Length of first segment Breadth of same anteriorly Breadth of same posteriorly Maximum breadth of strobila 0.42 0.80 0.28 0.50 0.90 0.12 3.5 5.0 Length of widest segments Breadth of posterior end of stro- bila 2.0 I^ATiTTiiim tViirUnf*^^ of ^amtf* 1.5 Concerning the cuticula little can be said, since the material studied was very poorly preserved. Only in sections of a very young strobila was it seen with any degree of certainty. There it was found to be about 4.5iu in thick- ness, and divided by differences in degree of staining into a dark outer one- 138 ILLINOIS BIOLOGICAL MONOGRAPHS [426 third composed of very closely set "cirri" and an inner two -thirds, which took the stain with great avidity, leaving only a thin outer hghter part which by its contrast in color with the cirrous stratum served to set the latter off dis- tinctly from the much thicker inner and more homogeneous part. The cuticu- la was not found to be in any way specially mxodified on the scolex, altho such might be found to be the case in weU-preserved material. It was naturally retained in its entirety only uithin the bothria. Only in the smallest strobilae could the subcuticula be made out satisfactor- ily. It is from 25 to 40/i in thickness, and composed of somewhat conical cells, the inner ends of which are quite cyhndrical while the outer are much branched, divergent and interlacing. Hence the cyhndrical portions, proximal to the nuclei and usually somewhat smaller in diameter than the latter, are seen to stand out distinctly and quite separately from the much less dense underlying parenchyma. The outer dendritic portions cannot be allotted v.ith certainty to their proper cell bodies on account of this com.plicated mesh-work which they form just beneath the cuticula, but they can be followed to the cuticula, their attachment to which is readily seen. Chalk-bodies in the poorly preserved parenchyma are usually elliptical in outline, \vith maximum lengths and widths of 18 to 26 and 11 to 15/i, respec- tively. They are fairly numerous and scattered thruout all parts of the strobila, being most plentiful in the cortex of ripe proglottides. In the scolex a ver>' few small ones are to be found only in the enlarged posterior portion of the organ, where they are confined to the medulla, no doubt on account of the great development of the musculature. They are also more numerous perhaps in the medullary portion of the parench>Tna of the anterior segments than in the cortical region. In general it would seem that they are developed in that portion of the parenchyma which is little occupied by other tissues or organs, chiefly muscles or genitaUa. The musculature of this species is very well developed and powerful. It was described by Linton (1890:729); but since his description is somewhat difl&cult to follow, the main features of its arrangement will here be given even at the expense of reporting much that has aheady been reported. The frontal series is well developed and consists of two layers on each sur- face of the strobila, an outer, just outside of the thick layer of main longitudinal muscles, and an inner, just within this or bounding the very thin medullary parenchjTna outwardly, as shown in figure 87. In the anterior segments a third series of frontal fibres appears as the posterior flaring border of the seg- ment is approached. It forms a ring around the whole strobila, i.e., connecting with its fellow of the opposite surface laterally, unlike the other two layers, just within the subcuticula or a little more than half way from the outer edge of the layer of main longitudinal fibres to the cuticula. This series as evidently pointed out by Linton, divides just ahead of the bay behind the posterior border of the segment, part of it going to the outer, posterior border and the rest remaining within. WTiile the latter as just indicated does not go far posteriorly, the former passes to the hinder edge of the salient border. In 427 J PSE UDOPH YLLIDEA FROM FISHES— COOPER 1 39 mature proglottides the layer of frontal fibres just external to the main longi- tudinal group is greatly thickened close to the posterior border of the segment. There it forms a transverse ropehke strand, no doubt owing in part at least to the numerous vitelline follicles situated in the cortex between these levels. And this statement applies in like manner, but especially more towards the median Hne of the strobila, to the innermost series of frontal muscles. These, however, are further interfered with chiefly by the uteri and cirrus-sacs. The sagittal or dorsoventral fibres are quite prominent on account of the fact that they are arranged in bundles which in the anterior segments find their way from the medulla out into the cortex between the fasicles of the main longitudinal series. They are less numerous laterally than medially. In mature segments, on the other hand, they are crowded and somewhat oblit- erated medially by the large genital organs, and are consequently more num- erous laterally, that is, beyond the edges of the uterus-sacs. Longitudinal sections show that large nimibers of them pass to the tip of the salient posterior borders of the segments and hence serve to retract the latter. The longitudinal muscles are present in two groups, an inner, or main, and an outer series. The former appears as a very conspicuous layer of large fibres arranged in fasicles or bundles on each surface of the strobila and occupy- ing one-half or more of the dorsoventral diameter of the cortical parenchyma. The latter are on the average much smaller, less numerous, more dispersed, and situated in the portion of the cortex between the outer frontal fibres and the cuticula. In the anterior segments the layer of inner fibres is about lOfx in thickness in the median line, and thins out gradually laterally where it joins its fellow of the opposite surface by a few fibres which lie in the plane of the flat, ribbon-hke medulla (Fig. 87). Linton does not seem to have noticed this lateral union of the two layers, since he said that "It [the longitudinal muscle layer] is, moreover, interrupted at the margins where it is penetrated by the margins of the inner core [the medulla]." Farther back where the segments become very broad and short it averages about 85/x in thickness, while in mature proglottides the thickness amounts to 145/i. At the same time the fasicles, in the anterior segments quite rectangular in outline, the longer diameter being dorsoventral in direction, become more elliptical in transection. In the latter case the individual fibres are circular to elliptical in trans- verse section and have a maximum diameter of 15^. In describing this group of longitudinal muscles in "transverse sections made thru that part of the body which is immediately in front of the segments that contain ripe ova," Linton stated that they "... are very large, altho not at this point in distinct fasciculi." This was not found to be the case in the sections studied by the writer, since fascicuH were seen all along the strobila even in the base of the scolex, altho it is true that anteriorly they are separated by only a small amount of parenchyma besides the bundles of sagittal fibres passing between them. As regards the other series of longitudinal fibres Linton rightly observed that "the longitudinal fibres of the inner part of the granular layer [here described as the outer portion of the cortex] do not differ essentially from those of the longi- 140 ILLINOIS BIOLOGICAL MONOGRAPHS [428 tudinal muscle layer proper, except that they are more scattered. ..." Centrally the individual fibres of this group are of the same diameter as the smallest of the main group, while peripherally they dwindle in size as they approach the cuticula to such an extent that there they are indistinguishable from the longitudinal cuticular fibres. Longitudinal sections show that they bear the same relations to the saHent posterior borders of the segments as are described here for Clestohothrium crassiceps and other species and emphasized by Liihe (1897a). Anteriorly a number of them pass ofif into the posterior border in the typical manner ; but, as might be expected, they are comparatively scarce in the posterior reaches of the strobila. Again, Linton stated that " the longitudinal muscular fibres in general do not lie parallel with each other. " This was found to be more strictly applicable to those within the fasicles, since only a comparatively few fibres pass from fasicle to fasicle longitudinally. But, as in other species, they are continuous from segment to segment as are indeed all of the groups of muscles, so that as far as their general arrangement is concerned, Linton's (1890:731) statements are thoroughly justified: "Longitudinal sections were carried thru several contiguous segments. In these there were no septa to indicate a division of the body into true segments. The only indication of a segmented condition is the superficial character of the projecting posterior edges. The longitudinal muscles are continuous and the ovaries [uterus-sacs] are crowded together so as to form an almost un- broken zig-zag line. So far as any internal characters go, the body is prac- tically continuous." The musculature of the scolex is especially well developed, the sagittal and radial fibres being very numerous. An unusual augmentation in the number of the former appears towards the outside of the walls of the bothria, extending from the dorsal to the ventral surface. Their exact course is ob- scured somewhat laterally in the median frontal plane by the interdigitation of the radial fibres which takes place there, that is, opposite the lateral grooves. As the posterior borders of the scolex are approached they diminish in number and size and eventually disappear. Coming into the base of the scolex as an elliptical ring in cross-section with its thickness almost as much laterally as dorsoventrally, the layer of main longitudinal muscles soon sends out dorso- ventral horns into the walls of the bothria on each side and becomes arranged in general much as in Clestohothrium crassiceps — doubtless an adaptation to the almost closed nature of the bothria. The outer longitudinal fibres are arranged on each side of the scolex as a continuous lateral band between the lateral sagittal fibres just mentioned and the cuticula, and extending from the dorsal to the ventral surface. Each bothrium has a much smaller and thinner band on each side next to the cuticula lining its cavity. The terminal disc is almost completely filled up with very powerful longitudinal arcuate fibres for the protrusion of its edges. In the anterior segments the two chief nerve strands are situated in the medullary parenchyma between the lateral and median quarters of the trans- verse diameter of the strobila. From 18 to 30/z in diameter, they fill up the 429] PSEUDOPHYLLIDEA FROM FISHES— COOPER 141 whole of the medulla dorsoventrally at these points. In mature proglottides they have the same relative positions in the frontal plane, but are located in the ventral one-half of the medulla, their transverse diameter being as much as 50/z. In the scolex each expands opposite the edges of the terminal disc to form a ganglion, which sends out a large branch to each of the two quadrants of the disc on the same side, and connects with its feUow by a sUghtly narrower commissure. Four main longitudinal excretory vessels maintain a constant course thruout the anterior segments. These are arranged in two pairs, a more median and a lateral, not in the same plane in the medulla. The members of the latter are the larger and are situated at the sides of the median one-quarter of the transverse diameter of the segment. All of these vessels are connected at various levels by large branches to form an extensive plexus thruout the medulla. In the posterior crowded segments, however, the main vessels become lost in the plexus, altho here and there they seem to occupy their origi- nal positions thru a few sections. Only two large vessels, probably the lateral pair, giving oft many branches of the same calibre, can be followed with cer- tainty into the scolex. About half way to the summit of the terminal disc they break up into a plexus v/hich ramifies thruout the walls of the bothria. The posterior end of the smallest strobila at hand showed the same sort of communication of a terminal plexus with the exterior thru large side branches and foramina secundaria as in B. scorpii. Linton (1889:457) described the reproductive organs in general in the following words: "In alcohoHc specimens a dark median hne will be noticed extending from the posterior end to the middle or anterior third of the strobila. This is due to the central situated ovaries [uterus-sacs], which are crowded with eggs. The genital apertures are lateral and may be traced in an irregular zig-zag line on one side from about the anterior third of the body. In the mature segments they are rendered obscure, if not wholly obUterated, by the mass of eggs with which the center of the segment is filled," and later (1890: 729, 730) besides giving the external features, quoted above, stated that "The reproductive apertures are near the median hne on one of the lateral sides. They are very close together and rather small. Each aperture represents a pair of sexual organs, cirrus and vagina. Upon making a few longitudinal sections on the lateral [dorsal] face which bears the reproductive apertures, the small vaginal opening comes into view. It opens into the common aperture from behind and near the surface. The large aperture continues into the cirrus- bulb. ..." Linton correctly stated that the common genital openings are arranged "in a zig-zag row" in the median line, as shown in figure 73; but much of this irregular lateral displacement in the mature proglottides would seem to be due to lateral pressure exerted by other organs, probably the gorged uterus-sacs or at least the uterine ducts, since in immature segments where the cirrus-sacs are already well developed, they are almost exactly in the median Une. In sagittal sections the genital cloaca is seen to open to the exterior at about the middle of the length of the very short mature proglottis 142 ILLINOIS BIOLOGIC A L M0N03R.\ PHS [13 0 and to be in many cases just covered by the posterior border of the segment iromediately ahead. It is in the form of a narrow tube, often somewhat enlarged ventrally, with a length of from 85 to 115/x and extending at right angles to the general surface of the strobila. A secondary genital cloaca or ductus hermaphroditicus is present at the bottom of this tube and is separated from the latter by a valve-like muscular extension of its walls (Fig. 88) . Behind this the cirrus is often found partially extended and directed backward towards the opening of the vagina or actually in contact with the vaginal sphincter. No sphincter muscle surrounding the genital cloaca at any level was found, altho a number of frontal fibres of the body muscles, curving around the structure both ahead and behind have the general appear- ance of such a structure. Very early traces of the reproductive rudiments were found in sections of segments 75mm. from the tip of the scolex of one of the largest strobilas studied. The testes, continuous from proglottis to proglottis, are spherical to ellip- soidal in shape, •^-ith their longest axes usually transverse in the latter case. The measurements from sections are as follows: width, 64 to 75/^1 ; length, 45 to 60; depth, 64 to 80. On account of their being closely and irregularly crowd- ed in the very short segments no attempt was made to count them directly; but the average number in the transverse sections (22 to 23) multiplied by the average for each proglottis from sagittal sections of a long series of seg- ments (3 to 4) gave about 67. The correct number is probably between 60 and 70. They are arraaged in a layer in the dorsal half of the medulla, where they show some tendency towards stratification. A few, however, were found outside of the medulla, that is beyond the inner frontal muscles and between fasciculi of the main longitudinal musculature. The vas deferens forms a compact mass of coils, closely appUed dorsolateral- ly to the proximal deflected end of the cirrus-pouch, and alternating irregularly from side to side constantly opposing the uterus-sac. In ripe proglottides it is quite compressed anteroposteriorly by the uterine tube, and also, as a consequence, often extends thruout almost the whole of the medulla dorsoventrally, in which case it is crescentic in outline in transverse sections with the concave side directed towards the median Une so as to somewhat sur- round the cirrus-sac. The average measurements of the mass of coils are: length, 0.085mm; width, 0.175; depth, 0.400. While it was found impossible to measure satisfactorily the size of the duct, gorged with sperms in the mass, it was seen to enter the base of the very muscular cirrus-sac with a diameter of 7.5)u. Within the latter it expands to 15/i and proceeds with this caliber in the form of a compact lot of close and somewhat spiral coils for about one quarter of the length of the pouch. In the second quarter, i.e., from the ventral end of the sac, it pursues a straight course and evidently functions as a quite efl&cient sperm receptacle since it is here usually from twice to three times as large as before. In the dorsal half of the pouch it again dimishes to from 5 to In and continues still in a straight course to the opening as the cirrus proper. Thruout its whole course its wall is very thin, including only a very 431] PSEUDOPHYLLIDEA FROM FISHES— COOPER 143 few circular and longitudinal muscle fibres. Distally the cuticular lining is reduced to a minimiun. Thus the cirrus when protruded, usually for a short distance only, is a comparatively weak structure with thin walls, but a diameter at the base of from 30 to 35/x. It is also quite short since in no place in the sections made was it found extended more than half way to the external opening of the genital cloaca, but more often, as noted above, turned around in the duc- tus hermaphroditicus towards the vaginal opening. Thus it is evidently adapted to the fimction of simply conveying the spermatozoa to the latter orifice in the act of self-impregnation rather than of acting as an intromittent organ in cross-fertilization. The diameter of the retracted cirrus was given by Linton (1890:730) as 0.008mm. The cirrus-sac is comparatively long and cylindrical and extends from the inner boundary of the genital cloaca to the median frontal plane of the pro- glottis. While its dorsal half is situated more at right angles to the surface, its ventral half bends over in the transverse plane to the right or left to become related to the coiled vas deferens in the manner described above. This deflec- tion of its proximal end thus alternates irregularly with the latter, and is always away from the uterus-sac. The maximum length and diameter in the latter case in the dorsal half of the organ are 0.500 and 0.145mm., respectively. As shown in figure 88, and as noted by Linton, the walls are very thick, leaving only a comparatively narrow cavity to accommodate the cirrus; they are com- posed of a very powerfvil inner layer of circular muscles surrounded by a thin layer of longitudinal fibres which do not have any points of attachment to the body-wall, so far as could be determined. The space surrounding the ejacula- tory duct and cirrus proper accommodates the fine and quite long retractor fibres and a small amount of parenchymatous tissue. The retractors are not, however, as large or numerous as in the previous species of the genus in which the cirrus is better developed. The vagina, which opens close behind the cirrus and usually somewhat towards the same side to which the latter is deflected, begins with a bulb-like sphincter, quite like that described and figured by Linton (1898:436) for his Dibothrium laciniatum, dOy. in length by about 90 in maximum diameter. The walls of this structure, 40/x in thickness, are composed of two layers of muscle fibres of equal thickness: an outer of loose circular, and an inner of somewhat radially arranged fibres. The whole organ would thus appear to be adapted to the pumping of the sperms into the vagina. The latter proceeds ventrally with a diameter of about 25/x, after enlarging considerably immediately behind the bulb. It is surrounded by circular fibres only. At the level of the ventral end of the cirrus-sac it joins the oviduct. The ovary, which has an average width of 0.45mm., is irregularly branched in mature proglottides, much compressed anteroposteriorly by the numerous coils of the uterine tube, and often displaced from the median hne by the latter and the spacious uterus-sac. Furthermore, while the isthmus, itself irregular in shape and hence somewhat difficult to distinguish from the rest of the organ, *'lies next the irmer side of the lateral [ventral] muscular wall," the wings 144 ILLINOIS BIOLOGICAL MONOGRAPHS [432 curve upward on each side, sometimes reaching aknost to the dorsal boundary of the medulla. The oocapt is almost spherical in shape with an average diameter of 30/i, and is situated in the median line. The oviduct immediately beyond the narrow outlet of the oocapt is 25/x in diameter. At the point of union of the vagina with the oviduct there seems to be a vestibule, similar to that of B. Scarpa, but this was not made out to the writer's satisfaction. Two vitelline ducts, each about 15^ in diameter, unite at about the level of the oocapt and continue dorsally with the same diameter as the common vitelUne duct. This turns downward again and quickly enlarges to form the vitelline reservoir, which was found to have a maximum diameter, when filled with yoUc cells of about 60/x. The vitelline foUicles are extremely numerous and very closely arranged in the cortical parenchyma in two lateral fields, a median strip being left free of them on each surface of the strobila. They are ellipsoidal in shape, with average maximum lengths, widths and depths of 35, 60 and 85/x, respec- tively. In the material studied they showed considerable tendency towards stratification and on account of this fact, their very varying size and the poor condition of their walls, no satisfaction was experienced in attempting to deter- mine the approximate number for each segment; but it must be well over one thousand from a comparison of the sections with those of B. cuspidatus. The uterine duct begins approximately in the m.edian line, quickly expands between the cirrus pouch and the ovary, first in the direction of the coiled vas deferens and as far laterally as the edge of the ovary, and then crosses the me- dian Une to the opposite side where the mass of coils, occupying the whole dorso- ventral diameter of the medulla, further enlarges gradually in all directions and joins the comparatively large uterus sac. In toto preparations the duct and sac are seen to form a continuous club-shaped mass gorged with eggs and with the larger end, the sac, alternating irregularly from side to side. This irregular alternation of the uterus-sacs was evidently not noticed by Linton since he spoke of only "a dark brown median stripe made by the ripe ova in the crowded ovaries [uteri] "; but Ariola (1900:410) said of them: "Le masse ovariche spesso sono irregolarmente coUocate da una. parte e dall' altra della linea mediana. " Only in sections can one distinguish the sac from the duct, since the two are so closely applied to each other. In dorsoventral view the uterus-sac, itself, is somewhat circular in outline, when not pressed against one of its fellows ahead or behind, and has a maxunima diameter of 0.45mm, Ventrally, however, it is funnel-shaped. As sho^vn in figure 73, it may become so enlarged as to invade the adjoining proglottides to a considerable extent. The aperture is located in the middle of the sac and consequently forms with its fellows two hnes of irregularly alternating pores on the ventral surface of the strobila, about l.Omni. apart. It is only about IO/jl in diameter, and is situated towards the anterior border of the proglottis, often well imder the overlapping posterior border of the segment ahead. The lowermost or funnel-shaped portion of the sac, Uttle more than that which passes through the stratum of longitudinal muscles, is surrounded by a thick layer of material, as shown in figure 97, the nature of which was not determined satisfactorily. It appears 433] PSEUDOPHYLLIDEA FROM FISHES— COOPER 145 to be glandular in nature, altho muscle fibres traverse the mass in several direc- tions, the inner of them being longitudinal and the outer circularly oblique. Altho this structure may have a glandular function in connection with the passage of the eggs to the exterior, it obviously acts as a powerful sphincter controlling the same and permitting perhaps of the laying of only a few at a time. Distal to the outer end of the funnel, where it loses these fibres, the sac continues through the cortical parenchyma as a narrow tube to the pore. The eggs of this species were said by Linton (1889 and 1890) to be of two kinds: "... one yellowish in moimted specimens with a strong shell, in some cases white and opaque; another sort transparent, with a very thin shell." These differences were seen in the material studied, but they were considered to be merely due to differences of age, the thinner-shelled ones being the younger. While the same author gave the length and breadth as 45 to 54/i and 27 to 30/x, respectively, the -^liter found their maximum dimensions to be in sections 58 by 34/z. The material studied consisted of two lots: No. 4711, in the collection of the United States National Museum, from the rectum of Tetrapterus sp. from Penekese, determined by Linton; and No. 16.461 in the collection of the University of Illinois, from the intestine of Histiophorus gladius, obtained from Prof. Linton, and evidently the actual specimen described by him in 1890. The details of the anatomy, here given, were studied from confirmatory sec- tions of the latter. DIBOTHRIUM LACINIATUM Linton Linton (1898:425) established this species on the basis of the material contained in lot No. 4741 of the collection of the United States Museum from Tarpon atlanticus, and again reported it from the same host species in 1901 (p. 437). Liihe (1899:43) in his Ust of the species of the genus Bothriocephalus s. str. remarked that "Von weniger gut bekannten Arten gehoren anscheinend noch hierher Bothriocephalus laciniatus (Lint.) und occidentalis (Lint.);" while Ariola (1900:414) also placed it in the same genus, as he conceived the latter to be constituted. During the study of B. manuhriformis the writer was impressed with the great resemblance between D. laciniatum and it, in all but a few details, the two being, in fact, identical. The measurements for length and maximum breadth, as shown m the comparative table below, agree, while those of the scolex and anterior segments are as near as can be expected from cestode material which is found in various degrees of contraction and relaxation. All of the conditions represented in Linton's (1898) Figs. 7 to 12, PL XXX, were observed in the material of B. manubriformis studied — ^when such obvious errors as, "Fossettes marginal as to head, corresponding to the flat surface of the body, " are taken into consideration— while the description of the external features, excepting that of the posterior segments, applied in detail. But later lot No. 4741, U.S.N.M., was obtained by Professor Ward, and the writer 146 ILLINOIS BIOLOGICAL MONOGRAPHS [434 learned that his suspicions were well founded; for D. laciniatum proved to be identical with B. manubrijormis. The posterior segments "with breadth one and a half times the length" had different proportions from those observed in mature material of the latter species, because they were, altho gravid, of quite youngers trobilas. The material of No. 4741 is, in fact, intermediate between No. 4711 of B. manubriformis and the 16.461 of the same species dealt with above, not so much in size since it does not show the regions so well, as in degree of maturity. The fact that " the segments are not uniform; one segment with a saUent posterior border followed by about two with less salient borders" is due to the irregular manner in which the primary segment divides into sub- segments. The dimensions of the eggs correspond, while the measurements of the cirrus-bulb, vaginal sphincter and calcareous bodies are the same in the two species. Linton stated that in D. laciniatum "The reproductive cloacae lie along the median hne of one of the flat surfaces of the body. The external openings of the uterus He along the median line of the opposite surface. " While the former was found to be the case, the latter was not, for the openings of the uteri he irregularly on either side of the median line as in B. manubriformis. Furthermore, the cirrus-bulb was not found to have "its inner end deflected to the right [left, when we take into consideration the fact that the common genital cloaca of D. laciniatum was considered to open on the ventral instead of the dorsal surface] where it communicates with the vas deferens, which lies in numerous folds in front and to the right of the cirrus-bulb," but to alternate irregularly from side to side according as the uterus-sac and distal end of the uterine duct occupy the other side of the proglottis; while the vas deferens was as described above (p. 142). Altho the vaginal bulb was found to be a little larger in the material of D. laciniatum, its structure and position were also quite as in B. manubriformis. On the other hand no muscle fibres completely encircling both genital apertures, such as shown in Linton's Fig. 5, PI. XXXI, were seen, but what might easily be taken for such were formed by the crossing of much curved and spread longitudinal and transverse fibres of the body wall, in such a manner that the portions intersecting at the four comers r\m in almost circular directions and concentrically parallel to each other so as to give the appearance of the whole forming a complete ring in each case. The genital cloaca was found to be shallower than in the material from Eistiophorus gladius. This is evidently due to the fact that the proglottides were yoimger and not yet gravid as in those from the latter host. The uterus- opening was not found to be "fined with cilia" but with irregular ragged processes which are evidently only portions of the lining of the developing fun- nel and the external duct of the same. FinaUy the position and structure of the ovary, of the vitelline reservoir and of the various layers of the body exactly correspond in the two forms. Consequently the writer feels that there can be no doubt whatever concern- ing the identity of D. laciniatum with B. manubriformis, which fact also seems to be recognized in the Fauna of the Woods Hole Region (Sumner, Osbom and Cole, 1913: 585) where the former is not found among the cestodes, altho 435] PSEUDOPHYLLIDEA FROM FISHES— COOPER 147 the host, Tarpon atlanticus, is hsted. Since B. manubriformis was described before D. laciniatum, the latter must now be considered as a species delenda. BOTHRIOCPHALUS HISTIOPHORUS Shipley The writer would also Hke to call attention in this place to the fact that Shipley's (1901) Bothriocephalns histiophorus agrees in all essentials with B. manubriformis, which is almost to be expected since both are found in the same host genus. The description and figure of the scolex is that of the latter species, altho the true nature of the bothria was not ascertained by Shipley on account of their almost closed condition, which was also seen in many specimens of B. manubriformis by the writer. Consequently it was described, erroneously, as " . . . provided with longitudinal slit-Hke depressions which hardly attain the dignity of suckers situated in the dorsal and ventral plane. " The external features of the strobila are the same in both species, altho Shipley was describ- ing a comparatively young specimen, as shown in his measurements of the scolex and in his figures showing" the size of the uterus-sac. The description and figures of the genitalia agree in almost all details. It is quite apparent, however, that his Fig. V, diagrammatic it is true, is entirely misleading as to the proximal connections of the reproductive ducts, one of which, the ootype, he confused with the isthmus of the ovary. The ova in the latter were found by the writer to be 15;u in diameter in B. manubriformis as in B. histiophorus. His description of these central connections of the genital ducts is certainly not that of the genus Bothriocephalus; for in dealing with the isthmus of the ovary, which he called the ootype, he said that "Into this region opens the small shell-gland, and the ducts of the yolk glands. The shell-gland lies posteriorly to the ovary between the right and left halves of that organ and with the ducts of the yolk glands it opens into the ootype posteriorly. " The measurements of the eggs and the description of the uterus agree with those of Linton's species, excepting that the opening of the uterus-sac '* . . . does not seem to be provided with anything of the nature of a sphincter muscle. . . " Altho the material at hand did not permit of the sectioning of such young stages in the development of the uterus-sac, it would seem from the somewhat varying nature of its funnel-shaped ventral end, described above for B. ?nanu- briformis, that in more anterior proglottides it might be in such a condition as to be easily overlooked. The nature and arrangement of the vitelline glands, the vagina and its bulb or sphincter, the testes in number and position, and finally the cirrus-sac, all considered in connection with his Figs. I-IV, force the writer to the conclusion that, so far as can be determined in the absence of material for study, Shipley's B. histiophorus n. sp. is identical with B. manu- briformis (Linton). Concerning the probable disposal of ripe eggs in B. histiophorus, Shipley made a statement with which the writer can agree, since it seems to be the natural conclusion to arrive at after a study of the varying contents of the uterus-sac along the strobila, namely, "From what I have seen I think it prob- 148 ILLINOIS BIO LOGIC JEL MONOGRAPHS 436] able that eggs pass out from the tapeworm into the alimentary canal of the host and that in B. histiophorus the eggs pass freely out from each proglottis and do not wait until the posterior proglottides break off to make their escape from the parent." In the following table a number of important measurements of B. manu- brifortnis, D. laciniatum and B. histiophorus are given for the sake of com- parison; all dimensions are given in millimeters: D. laciniatum B. histiophorus B. manubriformis Max-imum length of strobila Maximum breadth of strobila Breadth at posterior end Length of scolex Breadth of terminal disc Breadth of scolex at middle Breadth at posterior end Breadth at constriction Depth of terminal disc Depth of scolex, middle Depth at posterior end Depth at constriction Length of first segm.ent Breadth of same anteriorly Breadth of same posteriorly Length of median segments Breadth of median segments Length of posterior segments Breadth of same Length of cirrus-sac Max. diameter of sam.e Length of vaginal sphincter Diameter of same Dimensions of eggs Dimensions of calcareous bodies Number of testes Diameter of ova in ovarian isthmus 154 4 2 2 0.8 0.4 0.6 0.25 0.5 0.55 0.35 0.25 0.7 0.3 0.65 0.3 0.3 1 1.5 0.4 0.14 0.05 0.07 52x35m 17-24x8-14/1 1.8 0.4 0.3 0.16 ("ripe") 0.5 ("ripe") 45x35m 50-70 0.15 220 5 2 1.5-3.5 0.8-1.2 0.64 0.81 0.21-0.44 0.89 0.90-1.05 0.63 0.58 0.39 0.28-0.54 0.50-0.89 1.0 2.50 0.50 0.14 0.05 0.07 58x34/x 18-26x11-15m 60-70 0.15 437] PSEUDOPHYLLIDEA FROM FISHES— COOPER 149 BOTHRIOCEPHALUS OCCIDENTALIS (Linton 1898) [Figs. 28, 89] 1898 Dihothrium occidentale Linton 1898 :437 1899 Bothriocephalus occidentalis Liihe 1899 :43 1900 Bothriocepkalns occidentalis Ariola 1900 :415 Specific diagnosis: Witii tlie characters of tlie genus. Large cestodes witli maximum lengtli at least 310mm. and breadtli 5.5. Scolex small, elongate and somewhat rectangular, constricted posteriorly, 1.3mm. long by 0.46 wide. First segments somewiiat funnel-shaped; middle, densely crowded, ten to twenty times broader than long; posterior narrower and longer, 2 by 0.8mm., in groups of three or four. Cuticula 1.5ju in thickness. Calcareous bodies 18 by 13/i. Longitudinal muscles in bundles, outer series very scarce. Four chief excretory vessels, two much more prominent than the others. Genital cloacae form a narrow zig-zag row, each very shallow, no velum, cloaca and hermaphroditic duct united. Vagina op>ens directly behind the cirrus or a little to one side. Testes divided into two fields on each side by the nerve strand, 75 to 90 in number, 25, 85, and llSfx in average maximum length, breadth and depth. Coils of vas deferens loosely arranged, the duct 25/x in diameter, alternating irregularly from side to side opposite the uterus-sac. Cirrus long and cylindri- cal, 0.23 by 0.06mm., walls comparatively thin, most of the circular muscles being towards the inner end. No vaginal sphincter nor bulb. Ovary soHd, unbranched, 0.5 to 0.6mm. wide, 0.04 long and 0.13 to 0.18 deep. Oocapt 25ju in diameter. Vitelline fol- licles very numerous, the two lateral fields on each surface narrow, leaving a broad median strip free, 25, 60 and 115m m length, breadth and depth, respec- tively. ViteUine reservoir 45/x in diameter. Uterine duct voluminous on both sides of the median Hne, crowding all other organs. Maximum width and length of uterus-sac, 0.65 and 0.25mm., respectively; not encroaching much on neigh- bormg proglottides; ventral portion not especially modified. Uterus-openings alternate irregularly from side to side near the median line, far forward in the proglottides. Eggs 72 to 76 by 38 to 41^, dark brown, showing thru the walls of the distended uterus-sacs. Habitat: Intestine and pyloric coeca of the "rock cod, " Sebastodes sp. Type specunen: No. 4740 in the collection of the United States Museum, collected by T. H. Bean and identified by Professor Edwin Linton. Type locality: Whatcomb, Washington. The material contained in lot No. 4740 of the collection of the United States Museimi, upon which Linton based his species, was examined by the writer and confirmatory sections were made of mature segments; but it was all in such a very poor state of preservation that only a little can be added to the meagre descriptions already published. 150 ILLINOIS BIOLOGICAL MONOGRAPHS [438 Luhe (1899:43) stated under his diagnosis of the genus that "Von weniger gut bekannten Arten gehoren auscheinend noch hierher Bothriccephdus lacinio- tus (Lint.) und occidentalis (Lint.)," while Ariola (1900:415) included it in his compendium of the known species. Since no scolex and only very poorly preserved anterior parts of the stro- bila were found in the above mentioned lot, Linton's description is here given verbatim : "The bottle contained two fragments and portion of pyloric coeca of fish. The fragments measured 190 and 310mm. in length, respectively. Another fragment with scolex was found in one of the pyloric coeca; this was 115mm. in length. Head small, elongated truncate, and somewhat capitate, constricted near posterior end \\'ith prominent posterior margin; fossettes coincide with flat sur- face of body and extend posteriorly nearly to constriction; segments begin immediately behind head, somewhat funnel-shaped, soon becoming densely crowded and much broader, ten to twenty or more times as broad as long, decreasing in breadth and increasing in length again toward posterior end. Posterior segments in groups of three or four, namely, divisions between seg- ments of contiguous groups more distinctly marked than between other adjacent segments. Dimensions of head and segments: Length of head, 1.30mm.; breadth of head, apex, 0.46; middle, 0.46; base, 0.40; breadth of first segment, 0.42; length of first segment, 0.12; greatest breadth, 5.5; length of broadest segments, 0.25 ; breadth of posterior end, 2 ; length of posterior segments, 0.8. . . . The sides of the head which correspond with the lateral margins of the body are medianly depressed toward anterior end. " Concerning the cuticula nothing more can be said than that in the anterior segments where it did not seem to be much eroded, it was found to be only about 1.5/i in thickness. The subcuticular cells are closely crowded together. They form a s>Ticitioid layer, in which the comparatively large nuclei (8/z in diameter) stand out prominently, beginning about 35;u from the surface and extending centrally to the vitelline glands. As pointed out by Linton, "Cal- careous bodies are present in the central core [meduBa] and sparsely scattered elsewhere, but nowhere abundant. . . " The largest of them were found to be 18/i long by 13 wide, thus being vrithin the limits of measurements of those of B. mamibrijormis. In general the musculature is quite comparable to that of B. manubriformis. There is a stratvmi of frontal fibres on each surface of the layer of longitudinal fibres, but no third or outermost group in the anterior segments, doubtless owing to the fact that the posterior borders of the latter are not nearly so prominent. Both layers are related to the uteri and ciiTus-sacs in the same way. The sagittal fibres are m.uch less numerous especially anteriorly. Wliile the main longitudinal m^uscles, arranged in quite the same manner and with the same thickness, namely, 145^, render the cross-section of mature segments similar to that of B. manubriformis at first sight, the fibres of the external group 439] PSEU DOPEY LLIDEA FROM FISHES— COOPER 151 of this series are very scarce, confined to the anterior segments and very difficult to distinguish from the longitudinal cuticular fibres. The nerve strands, each about 35^ in transverse diameter anteriorly and 85/x thick by 45/i wide in mature segments, are situated between the lateral and median quarters of the transverse diameter of the strobila. Unlike con- ditions in the foregoing species, they occupy either the whole of the dorsoventral diameter of the medulla or are situated strictly in the median frontal plane, depending on the degree of lateral contraction. In the anterior segments two main longitudinal excretory vessels are located in the medulla between the nerve strands; while two others, much smaller and outside of the latter, are somewhat difficult to follow. In mature proglottides, however, all four vessels are fairly easily distinguished, especially in transec- tions. "The cirrus and vagina open by a common aperture on the middle of one of the flat surfaces of the body. . . . The vagina is behind the cirrus; in some cases directly behind it, in others a little to one side or other of the median line. " This was found to be in the main true, altho on close examination it is to be seen that the common genital openings form a zig-zag row as in the foregoing species. The uterus-openings, described as opening "externally on the middle of the dorsal surface, " likewise alternate irregiilarly from side to side. Furthermore, while the genital cloaca is situated at the middle of the very short proglottis, the opening of the uterus -sac is in the anterior portion of the segment, often being under the posterior border of the segment ahead. The cloaca itself is very shallow in this species, the openings of the cirrus and vagina being almost at the surface. There is no definite velum separating an inner ductus hermaphroditicus from an outer cloaca as in B. manubriformis. In the sections made, the testes, divided into two fields on each side by the nerve strand, were much compressed anteroposterior^ with average maxi- mum lengths, breadths and depths of 25, 85 and 115)ii, respectively. On ac- count of this crowded condition it was not found practicable to count their number directly in frontal sections, but it was calculated to be from 75 to 90. The vas deferens, averaging about 25^ in diameter, forms a number of loose, open coils extending thruout the whole dorsoventral diameter of the medulla on the side towards which the central end of the cirrus-sac is directed, and alternating irregularly from side to side as does the uterus-sac, but being constantly located on the opposite side of the median line from the latter. As it passes into the base of the cirrus pouch it has a diameter of only 3/i. In the proximal or central one-third of the sac it takes a few turns and then continues as a straight tube, somewhat larger (15/i) and usually filled with spermatozoa, the functional cirrus which is about S/x in diameter. The cirrus- sac is elongate oval to cylindrical in shape, the slightly larger end is ventral, and has a maximum length and a diameter of 230 and 60ju, respectively. It is thus approximately only one-half as large as that of B. manubriformis; nor does it extend ventrally past the lower edge of the layer of main longitudinal muscles. Its wall, as shown in figure 89, is comparatively thin, as pointed out 152 ILLINOIS BIOLOGICAL MONOGRAPHS [440 by Linton, especially in the dorsal half, the innet layer of circular fibres being much more numerous ventrally. Thus there is left a comparatively large space around the ejaculatory duct to accommodate the retractor muslces and a small amount of parenchyma the nuclei of which are situated peripherally much as in B. scorpii. A character which distinguishes this species, however, from others of the genus is the presence of a loosely arranged bundle of muscle- fibres attached to the ventral end of the crrrus-sac and passing downwards be- tween the coils of the uterine duct, beyond which they do not seem to have any definite attachment. Since the myoblasts and nuclei of these fibres are quite prominent, especially some distance from the cirrus-sac, the whole bundle has something of the appearance of an elongated gland. The protruded cirrus has a maximum length of 85/x with a diameter of 30;u. This everted condition of the cirrus, taken in conjunction with the nature of the genital cloaca de- scribed above, and the fact that there is no vaginal sphincter, points strongly to the cross-fertiUzation of at least different proglottides, rather than to self- fertilization. The former would, furthermore, seem possible betv/een con- tiguous segments, since in many cases two consecutive cloacae were found close together and at the bottom of an apparently temporary depression of the dorsal surface. The vagina has no sphincter, but begins somewhat broadly, as shown in Linton's figure 5, only to narrow down quickly to about 5^t half way along its course, which is almost straight ventrally. It expands slightly before joinmg the oviduct but does not form more than a temporarily functional seminal receptacle. The ovary, much compressed anteroposteriorly, is from 0.5 to 0.6mm. wide by only 40^i long at the isthmus, and from 0.13 to 0.18mm. deep. Its limbs are entire but much disturbed in their course laterally by the uterine ducts of contiguous proglottides. The oocapt has an average diameter of 25)u. Beyond it the oviduct enlarges, after constricting as usual, to about 25^ again where it is joined by the vagina. At the latter point there is a vesti- bule as in the last species. Just beyond this the oviduct is joined by the com- mon vitelline duct which is enlarged near the junction to form the yolk reservoir or "central vitelline mass," about 45/x in diameter. The vitelUne follicles are very numerous and closely arranged in the cortex in two lateral fields, leav- ing a broad median strip free of them on each surface of the strobila. Their maximvmi lengths, breadths and depths are 25, 60 and 115/i respectively; they have thus approximately the same bulk individually as those of B. manu- briformis. They are continuous at the edges of the strobila and occupy the central one-half of the thickness of the cortical parenchyma, excepting in the median free strips. While the rather small shell-gland occupies a somewhat limited position dorsally at the level of the ventral end of the cirrus-pouch, the uterine duct takes so many coils, all of which are filled with eggs, in the median portion of the proglottis on both sides of the midline that most of the other structures are all but obUterated — at least at first sight. Both the uter- ine duct and the uterus-sac are arranged pretty much as in B.manubriformis , but the latter is only from 0.27 to 0.37mm. wide by about 0.15 long and about 441] PSEUDOPHYLLIDEA FROM FISHES— COOPER 153 0.35 deep in proglottides where the whole median portion is gorged with eggs. In the widest segments, however, they may attain a width of 0.65mm. by a length of 0.25 but at the same time not encroach so much on the neighboring segments as in the last species; for the length of the broadest segments, as given above, is 0.25mm. The lower portion of the sac is not modified into a funnel-shaped structure, while the actual opening is only about 15ju in diameter. The measurements of the eggs are, according to Linton, 72 to 76ju in length by 38 to 41 in breadth. Such were found in the sections made, but no opercula such as shown in his figure 1 1 ; altho many similar appearances were considered to be only regular breaks in the shell. From the above description it is to be seen that in many respects this species is very close to B. manubriformis. But in others it is sufficiently different to warrant the retention of Linton's designation, the more so in view of the fact that the host was taken from the Pacific coast, the bothriocephalid fauna of which has apparently not yet been touched. CLESTOBOTHRIUM Liihe 1899 Bothriocephalus (part.) Rudolphi 1819 Dibothrius (part.) Rudolphi 1819 Bothriocephalus (part.) Leuckart 1819 Bothriocephalus (part.) Dujardin 1845 Dibothrium (part.) Diesing 1850 Dibothrivim (part.) Molin 1858 Dibothrium (part.) Diesing 1863 Bothriocephalus (part.) Cams 1885 Bothriocephalus (part.) Ariola 1896 Clestobothrium Liihe 1899 Bothriocephalus (part.) Ariola 1900 Clestobothrium Braun 1900 Scolex almost spherical, the free edges of the dorsoventrally situated bothria fused with each other in their whole extent in such a manner that only a small surficial opening near the apex leads into the interior of the spacious, hollow organ of attachment, flattened in the sagittal direction, by means of a short almost sagitally coursing canal which can be closed by a sphincter-like musculature. External segmentation complete. Vitelline follicles in the cortical parenchyma. Receptaculum seminis small. Beginning of the uterus a winding canal which leads into an extraordinarily spacious uterus-sac, dis- torting all other genital organs in ripe proglottides. Uterine opening about median as is the dorsal genital opening. Type and only species: C. crassiceps (Rudolphi). 1 54 ILLINOIS BIOLOGIC A L MONOGRA PHS [442 CLESTOBOTHRIUM CRASSICEPS (Rudolphi 1819) [Figs. 29-31, 48, 49, 58, 74, 75, 90, 103, 108] 1819 Bothriocephalus crassiceps Rudolphi 1819 : 139, 476 1819 Bothrioccphalus pilida Leuckart 1819 :45 1845 Bothriocephalus crassiceps Dujardin 1845 :617 1850 Dihothriiim crassiceps Diesing 1850 :587 1858 Dibothrium crassiceps Molin 1858 : 134 1863 Dibothrium crassiceps Diesing 1S63 :236 1885 Bothriocephalus crassiceps Cams 1885 : 120 1896 Bothriocephalus crassiceps Ariola 1896 :280 1899 Clcstobolhri2{m crassiceps Liihe 1899 :44 1900 Bothriocephalus crassiceps Ariola 1^-00 -.397 1900 Clestobothrium crassiceps Braun 1900 : 1692 1901 Dibothrium crassiceps Linton 1901 : 411, 451,473 1909 Dibothrium crassiceps Johnstone 1909 :87 Specific diagnosis: With the characters of the genus. Medium sized ces- todes, up to 92min. in length, with a maximum breadth of 1.5mm. Anteriorly surface of body with closely arranged transverse furrows, posteriorly segmenta- tion more distict, serrate. Scolex globose, 0.64 to 1.08mm. long, 0.52 to 0.90 broad, and 0.68 to 1.21 thick; divided by longitudinal marginal grooves into two dorsoventral hemispheres, the bothria. Latter large, prominent, oval, their apertures about one-third their length from the apex and connected by a saddle-shaped groove over the tip of the scolex, with prominent lips. No neck, segmentation beginning immediately behind the scolex. Young segments closely arranged, five to six times as broad as long; mature proglottides quad- rate to twice as long as broad, frequently divided on one or both sides by spurious articulations usually behind the uterus-sacs. Cuticula 2 to 5yi thick, subcuticula 20^. Chalk-bodies absent. Muscula- ture well developed, powerful sphincter around orifice of bothrium. Chief nerve strands ventral, 15 to 20^ in diameter. Usually four longitudinal ex- cretory vessels. Genital cloaca median, dorsal, three-fourths to one-half the length of the proglottis from its anterior end, usually just posterior to the spurious articula- tions; hermaphroditic duct within cloaca. Testes in two lateral fields in the medulla; ellipsoidal in shape, 0.125mm. long by 0.04 in diameter, continuous from joint to joint, 40 to 50 in each proglot- tis. Vas deferens forms a wedge-shaped mass of coils ahead of cirrus-sac and alongside of the hinder end of the uterus-sac. Cirrus-sac elliptical to some- what oval, 0.128 to 0.162mm. long by 0.087 to 0.116 wide and 0.098 to 0.116 deep, immediately behind the uterus-sac or lateral to its posterior end. Cirrus- sac and vas deferens together alternate irregularly from right to left opposite the hinder end of the uterus-sac. Opening of vagina close behind that of cirrus. Receptaculum seminis present as a short diverticulum almost parallel to the o\dduct at the point of union of the vagina with the latter, about lOju in diameter. Ovary bilobed, the isthmus narrow and ventral, ova in same 18 by lO^i. Oocapt 20ju in dia- 443] PSEUDOPHYLLIDEA FROM FISHES— COOPER 155 meter. Vestibule at the point of union of the vagina with the oviduct. Vitel- line duct expands into a reservoir 30^l in diameter. Vitelline follicles not in lateral fields, but continuous from joint to joint, 60 by 30 by 50ju in dimensions, about 700 in each proglottis. Uterus-sac elliptical in outline, directed antero- posteriorly in the anterior half of the proglottis, where in gravid segments it occupies almost the whole of the medullary region; 2.20 by 1.34mm. in dimen- sions; in quadrate segments irregularly alternating from side to side as are the uterine openings. Eggs, 75 by 40^. Habitat: In the anterior portion of the intestine of the host. HOST LOCALITY COLLECTOR AUTHORITY Gadus merluccius Naples Rudolphi Rudolphi 1819 : 139 (Type host) (rodiis merluccius Leuckart Leuckart 1819 : 45 Gadus merluccius Patavia Molin Molin 1858 : 134 Gadus merluccius Trieste Stossich Cams 1885 : 120 Gadus euxinus Trieste Stossich Stossich 1899 : 1 Merlangus carbonarius Nizza Wagener Wagener 1854 : 61 Merlangus sp. Merluccius bilinearis Wagener Linton Wagener 1857 : 93 Woods Hole Linton 1901 : 473 Merluccius esculentus Parona Ariola 1896 : 265 Merluccius esculentus Trieste Stossich Stossich 1898 : 115 Merhiccius merluccius Pisa Wagener Wagener 1854 : 68 Merluccius vulgaris Ireland Drummond Thompson 1844 : 439 Merluccius vulgaris Patavaa Molin Molin 1861 : 235 Merluccius vidgaris Pisa Wagener Diesing 1863 : 237 Merluccius vulgaris Padova Molin Diesing 1863 : 237 Merluccius vulgaris Geneva Parona Ariola 1896 : 265 Merluccius vulgaris Portaferrajo, Id. Elba Damiani Parona 1899 : 8 Merluccius vulgaris Pisa Parona Parona 1899 : 8 Merluccius vulgaris Gaeta Ariola Ariola 1900 : 397 Merluccius vulgaris Augusta, Barbagallo and Barbagallo 1903 : 412 Catania Drago and Drago Pomatomus saltatrix Woods Hole Linton Linton 1901 : 451 "AsmaUhake" Calf of Man, England Johnstone Johnstone 1909 : 87 Merluccius bilinearis Passamaquoddy Cooper Cooper Bay, St. Andrews, (the present paper) N.B. Merluccius bilinearis Buzzards Bay, Mass. Cooper )) Merluccius bilinearis Vineyard Sound, Mass. Cooper )> Merluccius bilinearis Casco Bay, Me. South Harpswell Cooper » 156 ILLINOIS BIOLOGICAL MONOGRAPHS [444 In external appearance this species is characterized by the globose nature of the scolex and the serrate margins of the strobila, the former of which was the basis of Leuckart's (1819:45) specific name and which with the latter was emphasized and included in the diagnoses given by all the authors after Rudol- ph! (1819). But another important character which also assists in the ready recognition of the species is the presence of spurious articulations, which, how- ever, are evidently not those mentioned collectively by Wagener (1854:69) as "articulatio spuria." The scolex (Figs. 29-31) is divided by two longitudinal marginal grooves into two dorsoventral hemispheres, the bothria. The latter were considered by Rudolphi (1819:130, 477) and others to be marginal in position, but many years elapsed before this error was finally and definitely corrected by Liihe (1899:35). F. S. Leuckart (1819:45) rightly described and figured the scolex as "medio marginali sulcato, foveis lateraUbus. ..." and "Die Randflache des Kopfes ist breiter als die Seitenflache, die mittelfurche jener ziemhch tief, und bi det an jener Seite eine erhabene, in der Mitte hellere Wolbung. " It seems that Molin (1881:235) fell into the error of considering the marginal or lateral grooves, separating the bothria, to be the bothria themselves, as indicated in his diagnosis: "Caput magnum subglobosum, utrinque sulco longitudinaH laterali, apertura centraU bilabiata antica, bothriis ovaHbus, subter min- alibus, marginahbus, longis"; and in his " Osservazione 2" he said: "Quan- tunque la testa sia molta grossa ed opaca, cio non per tanto potei distinguere il solco menzionato da Diesing [1850:587] il quale pero corrisponde ai lati e non ai margini del corpo, e sembra dividere la testa in due emisferi, Ognuno di questi porta ima fossetta oblimga, ovale, che si estende dall' apice a due terzi della lunghezza del corpo, e sembra di quattro quadrant! suddivisi da due solchi che s'incrocciano. " It is evident from his figure 2, Taf. V, that the "fossetta oblunga" is the entrance to the bothrium, but he does not seem to have observed the actual opening. Matz (1892:103) expressed the opinion that the bothria of this species are dorsoventral in position, while Ariola (1896:280) evi- dently on the basis of former descriptions placed the species among those of the genus Bothriocephalus Rud. with "Botridi marginali." Stossich (1898: 115) also described the scolex as " ... subglobosa, con botridii marginali, subterminaU, ovato-allungati. " Ariola (1900:398) finally corrected his own view of the external structure of the scolex by saying that "Un esame anche superficial dimostra pero che la posizione degU organi di fissazione non e equale fu ritenuta, perche ciascun d'essi corrisponde ad una faccia larga dello strobila, o como si dice, sono dorsoventrah. I pretesi botridii marginali sono dati da un solco circulare, abbastanza profondo, che corre a guisa di un meridiano attomo alio scolice globoso, passando per I'apice, e dividuendolo come in due emisferi, imo destro a I'altro sinistro," thus evidently ignoring the fact that Liihe had already (1899:25) performed the service for students of the group, as he later pointed out with justifiable emphasis (Liihe, 1901:414). The bothria in this species are sac-like structures, formed (phylogenetically) as indicated in the generic diagnosis, by the rolling together of their edges or 445) PSEUDOPHYLLIDEA FROM FISHES— COOPER 157 "walls" and the fusion of the latter for most of their extent "in such a manner that only a small lateral [dorsoventral] opening in the region of the apex leads into the anterior of the spacious, hollow organ of attachment. " The size and shape of the opening itself varies considerably in preserved material. It may be so small (Fig. 29) as to be seen only on very close examination or in sections, or comparatively large (Fig. 49), depending on the stage of contrac- tion or enlargement of the bothria when the individual is fixed or preserved. During life it may be seen to undergo such variations in size while the whole scolex isbeing elongated and retracted during the characteristic sucking move- ments. Rudolphi (1819:477) correctly described the bothria as", . . oblonga profunda et magna in vivis; in mortuis bothrii ostium parvum anticum adesse videtur." In lateral view (Fig. 30) the bothria are seen to be more sharply oval or even conical in outline, as is consequently the whole scolex, owing to the fact that the dorsoventral diameter of the lumen of each is much greater in its posterior half than in its anterior half. It will also be noted more clearly from this aspect that the hinder borders of the bothria project a considerable distance beyond the true anterior end of the strobila. Thus the length of the scolex is not that of the bothrium, as many writers have evidently taken it to be, but as far as can be determined from external views, more nearly that of the marginal sulcus plus an extension of the same to the tip of the scolex, or, where the latter is retracted, to the anterior border of the labia. The breadth of the scolex is here taken for the sake of convenience to be that of the bothrium, since there is very little difference between the two in this regard. The two apertures of the bothria are united over the tip of the scolex by a saddle-shaped groove, the edges of which are somewhat swollen so as to form lip-like struc- tures. This groove has been described and figured for C. crassiceps by Molin (1861:235, Fig. 2, Tab. V) and Ariola (1900:397, Fig. 17, Taf. VIII) and figured by Linton (1901a :Fig. 267, PI. 24), but it does not appear either in the figures given by Wagener (1854 :Fig. 75, Taf. 7; 1857 :Fig. 6, PI. II) or that by Johnstone (1909:87, Fig. 14). It is present in all of the writer's material even to the youngest, but in a few cases the tip of the groove, that is the extreme tip of the scolex, is so prominent as to more or less obliterate the lips (Fig. 49). It is also to be noted that the lateral grooves separating the bothria do not pass thru these lips. This is nicely indicated in Ariola 's figure but erroneously described by him as "passando per I'apice, " and as further figured but in the same relation by Johnstone. Wagener's figure 75 and Linton's figure 266 also give the erroneous impression that this groove passes right over the tip of the scolex. Molin (1861:235), while giving a somewhat confused descrip- tion of the relations between the saddle-shaped structures — which he figures as including the apertures of the bothria more posteriorly — and the lateral grooves, says that he saw in the apex an aperture which not only ended blindly but which was bounded by two eminences, simulating lips. This may have been due to extreme contraction of the tip of the scolex between the lips of this groove. It will be recalled that Leuckart (1819:46) stated in this connection that "An dem Kopfende ist eine kleine Vertiefung in der Mitte; die von den 158 ILLINOIS BIOLOGICAL MONOGRAPHS [446 beiden sich hier vereinigenden Randfurchen herriihrt, wodurch ihre Rander etwas erhabener werden. Die Griibchen sind kaum von der Grosse eines Nadelknopfchens iind tief in Kopfe, so dass es fast scheinen konnte, als waren sie wahre oscula;" but his figure 26, very good in other respects, does not do justice to his description of these terminal structures. Compare also Lonn- berg's (1893: 15-17) B. neglectus, the figure for the scolex of which looks very much like B. crassiceps. There is no neck in this species, but segmentation begins immediately behind the scolex (Fig. 48) and is complete thruout the strobila. These characters were included by Liihe (1899:44) in the diagnosis of the genus: "Aussere Gliederung vollkommen, ein gegUederter Hals fehlt. " As regards this quo- tation, it would appear that the "gegUederter" is either superfluous or a lapsus calami for " ungegliederter. " The anterior border of the first segment, a greater part of which is obscured by the hinder edges of the bothria, is con- stantly somewhat narrower than the latter, but its posterior border is usually about the same width even in such contracted specimens (Fig. 29). Its out- line is somewhat trapezoidal, while its length is slightly greater than that of the segment immediately following. The breadth of this first segment varies anteriorly from 0.40 to 0.92mm. and posteriorly from 0.65 to 1.16 — Linton's measurements are 0.78 and 1.07, respectively. Following this the segments are closely set, five to six times as broad as long, while their somewhat thickened posterior borders protrude on either side (as well as dorsoventrally) so as to give the strobila a serrate appearance (Fig. 48). It is here that the formation of new proglottides takes place by the subdivision of preexisting segments. This serrate appearance is also present in the posterior part of the strobila, where the proglottides are quadrate to twice as long as broad. Posteriorly each serration does not necessarily define the posterior border of a proglottis. This is due to the presence of spurious articulations, possibly included in Wagener's "articulatio spuria." These are furrows which arise laterally, where they do not stand out as distinctly, however, as the true pos- terior borders of the proglottides, but do not pass to the median line. They are not present in all of the posterior proglottides nor are they symmetrically arranged. In the following excerpt from his more complete diagnosis it is to be seen that Rudolphi (1819:477) did not refer to these structures: "Articuli breves, margine posteriore incrassato utrinque exstante, quo corpus serratimi fiat. ArticuH ceterum inaequales, ut passim augustiores et longiores intercurrant. " F. S. Leuckart said only, "Die ersten GUeder am Kopfe schmaler als die tjbrigen, dann folgen fast gleichbreite, die letzte Halfte der GUeder breiter als lang, mit deutUchen, weissen Ovarien," which statement refers to "der beschreibene nicht ganze Wurm . . . 13^" lang." Diesing (1863:236) described the strobila as " . . . el- Upticum, arricuUs ad medium usque increscentibus, inde descrescentibus, marginaUbus posticis utrinque prominentibus, articulo singulo pUca transver- saU diviso ..." The latter has reference obviously to Wagener's " articulo spuria." It is also seen that, as regards the shape of the strobila, he 447] PSEUDOPHYLLIDEA FROM FISHES— COOPER 159 (Diesing) was dealing with much contracted specimens, the length being cited as ranging from one and a half lines to two inches. Ariola (1900:397) gave the following description of the segments: "StrobUa anteriormente assai piu stretto dello scolice, a guisa di pedimcolo; le primi proglottidi sono rettangulari, strette, ma rapidamente si allargano; raggiunta la massima dimensione, la conservano sino all ultimo tratto del corpo, dove nuovamente si restringono. Le proglottidi mature hanno angula posteriori appena visibili; le ultime presentano forma trapezoidale. " And Johnstone (1909:89) stated, "The posterior proglottides are much broader (in the transverse axis of the strobila) than they are long (in the longitudinal axis of the strobila) ; and their anterior extremities are narrower than the pos- terior ones, so that the edge of the strobila appears to be serrated. Secondary- segmentation of the proglottis often occurs. " In fine, Wagener, Diesing, and Johnstone are, to the writer's knowledge, the only writers who have referred to this spurious articulation or subdivision of the segments into false secondary segments — although Liihe (1902:629) repeated the statements of the first two authors. Furthermore, Wagener did not figure the adult strobila of the species to show the structures in ques- tion, but in the legend for his figure 79, Taf. 7 of Dibothrium heteropleurum, — now Amphicotyle heteropleura (Diesing) — says only that "Man sieht die articulo spurio, welche die echten GUeder, wie bei Dibothrium crassiceps, in der Mitte theilt"; and further, as regards the difference in structure of the sides of this species, "Der Schein entsteht durch die noch dichtere Zusam- mendrangung der Falten der wahren und falschen Glieder auf der concaven Seite. " In the legend (p. 61) for his figure 6, the egg of C. crassiceps, he also said that " Jedes Ghed hat in der Mitte eine Falte, die ihm das Ansehen giebt, als bestunde es aus zwei Gliedem. " Thus, there is reason to beUeve that for this species no one (apart from Linton's Fig. 268) has as yet described nor figured what the writer here calls spurious articulations, but that these workers were referring to the secondary division of the segments of the anterior end of the strobila which proceeds in the manner described for B. scorpii et al., altho not so clearly (Figs. 48 and 58). This is borne out by the fact that the spurious articulations described here never reach the median fine of the strobila, much less pass completely across it as do the true posterior borders of the pro- glottides (Fig. 74). In one moderately relaxed strobila the first segment show- ing spurious articulations appeared 11.7mm. from the tip of the scolex, while in another which was quite contracted, especially anteriorly, 4.8mm. In the former case the next two pairs of these structures — and all of these in question happened to be bilaterally symmetrically situated — appeared in the fourth and thirteenth segments following. Posteriorly the uterus-sacs appear as a series of gradually enlarging, dark punctations, as described below, not so pronounced, however, as in B. scorpii. The measurements of the first proglottis showing eggs in the uterus-sac in a fairly relaxed strobila at hand were 0.50mm. in length by 0.92 in breadth, while for one farther back where the uterus-sac was 0.61 by 0.48 160 ILLINOIS BIOLOGICAL MONOGRAPHS [448 mm., they were 1.31mm. in length by 0.82 in width. These measurements are, however, of only relative value. Another strobila of the same age but con- tracted at the time of fixation might show the same regions more like those farther ahead and, thus, in alcohoHc specimens, evidently younger. The following table gives various external measurements of six specimens in alcohol for the purpose of comparison; all dimensions are in milUmeters. Length in mm. Length of scolex (lateral view) Length of bothrium Breadth of same Thickness of same Breadth of segment I, anteriorly Breadth of same, posteriorly Thickness of same, posteriorly Maximum breadth in anterior part of strobila Same in posterior part of strobila 87 0.87 1.08 0.75 0.87 Much contracted Ditto 0.37 1.01 1.11 92 0.59 0.77 0.57 0.64 0.40 0.53 0.38 0.82 1.04 Little 43 more than scolex 0.46 0.43 0.64 0.64 0.52 0.53 0.68 0.58 0.37 0.60 0.53 0.24 0.27 1.06 1.16 29 0.63 1.00 0.67 0.74 0.55 0.74 0.52 1.30 1.48 72 0.83 1.01 0.90 1.21 0.92 1.16 1.38 The cuticula varies in thickness from 2 to 5n, the most common measure- ment being about 2.6/x. Resting on a distinct basement membrane, well shown after the use of Mallory's stain, it is divided into two strata of equal thickness by a granular layer, the components of which seem to be related to the bases of the stout, somewhat club-shaped pseudociha or "hairs "which constitute the outer moiety. While the inner stratum was found to be homogeneous with the stains used, the outer showed two intensities of color, an inner hghter and an outer darker. The former represents the narrowed central ends of the spindle- or club-shaped pseudociha, while the latter is determined by the well- stained bodies of the cirri themselves. Linton (1901:473) said that "the cuticula is covered with minute spines," but Johnstone (1909:89) said, con- cerning these structures: "I can see nothing of this kind in the species before me. " All over the scolex and in the form of a band on the posterior borders of the proglottides (Fig. 103) these cirri become modified into stouter spinelets from two or three times longer than elsewhere and everywhere directed pos- teriorly, quite hke those described by the writer (1914a:85) for Haplobothrium glohuliforme, but much longer relatively; thus indicating their function as accessory organs of attachment. The largest spinelets are in the middle of this band, those at the edges, that is in the anteroposterior direction, gradual- 449] PSEUDOPHYLLIDEA FROM FISHES— COOPER 161 ly merging in length into the pseudocilia of the cuticula of the neighborhood. -Furthermore they are arranged in the same manner on the posterior borders of the spurious articulations and of all of the secondary segments situated in the anterior portion of the strobila. They were referred to by Wagener (1854: 5), Diesing (1863:236) as "articulo singulo . . . postice ciliis instructo," Cohn (1902:55) and by Luhe (1902:238, 247) who considered "dass es sich nicht um in die Cuticula eingesenkte Stacheln handelt, wie bei dem Stachel- kleide so vieler Distomen, sondem nur am Fortsatze der Cuticula, durchaus analog denjenigen, welche Looss an der bereits oben citierten S telle fur Haema- toloechus as per abgebUdet hat. " The subcuticula, about 20^ in thickness, consists of fairly elongated cells, the nuclei of which are situated at their central ends close to the vitelline follicles. Their boundaries are difficult to ascertain, the whole layer thus being more of the nature of a syncitium. For about one-third of their length im- mediately beneath the cuticula the cytoplasm becomes broken up into a num- ber of more or less parallel processes which stand out in distinct contrast with the deeper inner ends of the cells, especially in transverse sections. The parenchyma, everyv/here encroached upon by the voluminous repro- ductive organs, is in the form of a comparatively open reticulum showing no features of special interest. It is naturally most abundant in the posterior flared ends of the proglottides. In small strobilas it is more compact in struc- ture and contains relatively more nuclei. Distinct spaces, formerly occupied by calcareous bodies, such as are readily and distinctly seen in the parenchyma of B. scorpii, were found neither in the scolex nor in the strobila; nor were these structures noticed in living material. The musculature is composed of the typical three sets of fibres, interfered with in the usual manner by the large reproductive organs and their external openings. The sagittal and frontal series are only moderately developed, while the longitudinal series is about 10/z in thickness and situated within the frontal series. Its fibres are arranged in bundles of irregular shape (in cross-section) and width but of this uniform thickness, excepting where they are naturally much flattened out dorsally and ventrally by the distended uterus-sac. They are also continuous from joint to joint. A very weakly developed series of outer longitudinal muscles is present, while the muscles of the posterior border of the proglottis (vide Liihe 1897a) are poorly developed, in fact even less so than in Bothriocephalus. In the scolex the frontal fibres are better developed than the sagittal ones, and pass around the bothrium closer to its lumen than to its external surface, while the latter are mostly confined to the region between the bothria. The inner longitudinal muscles of the strobila pass forward into the scolex, dividing as they meet the lumina of the bothria to pass around them and attach them- selves to the margins of the apertures. They are thus directed somewhat obliquely as shown in Johnstone's figure 18 and described as ". . . running irregularly, probably obhquely, round the walls of the bothrium. These no doubt function as constrictors of the latter. " A few pass on forward to the 162 ILLINOIS BIOLOGICAL MONOGRAPHS [450 tip of the scolex to assist in activating that region. Between the bothria, how- ever, they were found to be separated into dorsal and ventral layers as in the strobila, and not united into a single coronal band, as shown by Johnstone. The bothrial sphincter (Fig. 48) is a powerful bundle of fibres, about 0.07mm. in transverse section surrounding the aperture close to its cuticula. In trans- verse sections of the scolex it appears as a deeply staining mass on each side of the opening, also shown in Johnstone's figure 15. As it crosses the aperture anteriorly it becomes greatly attenuated. This with its comparatively great size at the sides and posteriorly accounts for the ahnost complete disappearance of the aperture in many adult, preserved scolices owing to the powerful con- traction of this muscle from behind forward, thus dimxinishing the opening towards the tip of the scolex. From their arrangement it is to be seen that this sphincter, evidently a modified group of frontal fibres, and the longitudinal muscles in the scolex play a more important role in the movements of the bothria than do the other groups. On account of their obhque course the longitudmal fibres evidently act in diminishing the size of the lumen of the bothrium as well as do the circular frontal fibres of the latter. The nervous system consists of two longitudinal strands which enlarge in tip of the scolex to form two somewhat elongated ganglia. The latter are united by only a few fibres, but they send out comparatively large nerves to the bothria. In the strobila the chief strands, each from 15 to 20yu in diameter, are situated ventrally in the medullary parenchyma, just within the longitudinal muscles and from one-fifth to one-quarter the width of the strobila from its lateral margins (Fig. 90). About halfway along the scolex the strands are about 80/i in diameter ; but the gangUa are somewhat smaller and situated close together about 0.15mm. from the summit. In other words the chief strands enlarge and diverge gradually until the equatorial region of the scolex is reached and then diminish in size as they converge to form the ganglia. A pair of prominent nerves is sent forward on each side to supply the saddle-shaped groove described above. In young strobilas the nerve strands are situated midway between the dorsal and ventral surfaces, and not ventrally. The excretory system consists of a pair of longitudinal vessels, situated ventrally, that is, in the same frontal plane as the chief nerve strands, each vessel being in the anterior end of the strobila about halfway between the nerve strand and the median row of reproductive rudiments. These vessels break up in a very irregular manner into extremely elongated loops, so that for considerable stretches four vessels will appear while again the branchings will be so numerous as to make it very difficult to decide, on looking at a transverse section, which are the main channels (Fig. 48). In other individuals four ves- sels appear, so that one is led to conclude that the pair just mentioned represent the latter, fused at times but separated again to form the loops. But whether these four vessels represent the typical four of other orders is a matter of con- jecture. These main vessels may continue back into the ripe joints close alongside the uterus-sacs, but they usually break up into a very diffuse reticu- lum throughout the medullary parenchyma in the region where the openings 451] PSEUDOPHYLLIDEA FROM FISHES— COOPER 163 of the cirrus and vagina pierce the cuticula in development. Behind this region it was found impossible to trace the main vessels with satisfaction. The system usually passes into the scolex as two vessels, but soon breaks up into an elaborate net-work which ramifies between the bothria and throughout their walls. These branches are shown in Johnstone's figure 15. As regards the conditions of the excretory system in the extreme posterior end of the strobila, the material at hand permits of only negative conclusions. In the youngest strobilas, such as that shown in figure 49, the vessels converge pos- teriorly to open into a notch in the cuticula, there being no definite terminal vesicle such as is presen*- in plerocercoids of the genus Proteocephalus, for instance. From this and the further fact that Wagener (1857:93) showed (Fig. 6, PI. II) the main vessels in a very small strobila, which he examined while it was alive, passing separately to the outside, one is led to conclude that the vesicle, if ever present, must have been situated in the walls of an envelop- ing cyst and disappeared with the latter as in the Trypanorhyncha or the Cyclophyllidea. This seems to have been Wagener's idea of the situation when under his figure 65 (1854:68) he said: "Man sieht keinen pulsirenden Schlauch am spitzen Schwanzende. Es muss dies Thier auf ahnliche Weise entstanden sein, wie das in Fig. 74 dargestellte, " and figure 74 is that of "Di- bothrium (Belones ?)" from Scyllium canicula enclosed in a cyst in the walls of which "man sieht die Gefasse der Cestodenblase. " The earliest reference to the genitaHa of C. crassiceps was by Rudolphi (1819:477) who said: "Ova vel ovaha vel ovata, forsan secundun majorem maturitatis gradum. A B. punctato diversissimus, licet ovaria lateralia fuscescant, sed haec ipsa etiam in B. crassicipite quam in B. punctato majora sunt." The structures called ovaria were evidently the uterus-sacs. F. S. Leuck" art (1819:46) described the reproductive organs of his B. pilula as follows: " . . . die letzte Half te der GHeder breiter als lang, mit deutlichen, weissen ovar- ien. An den unteren Gliedem sieht man oberhalb jedes Eierstockes einen was- serhellen Punkt, wahrscheinlich Oeffnung fur das mannliches Zeugungsglied." From a comparison of this with his description and figure of posterior proglot- tides of B. scorpii, it is evident that he too was dealing with the uteri and their openings, respectively. He also referred to ". . . den schwarzen Punkten des Korpers, die Rudolphi fur Ovarien gehalten" of Redi's worm, which Rudol- phi called (1810:67) Bothriocephaliis gadi merluccii and placed in his "Species dubiae." Wagener (1854a:61) said that "Die Eier haufen sich in obersten Theile der Glieder an. Der Dotterstock verzweigt sich uber das ganze Glied und liegt overhalb der vescicules transparentes van Beneden. Die Gesch- lechtsoffnung ist in der Mitte und lateral." Diesing (1863:236) placed the "Aperturae genitalium laterales in linea mediana." Ariola (1896:265-266) gave the first comprehensive description of the reproductive organs in the following words: "Tuttaria sul corpo si osservano macchie scure molto sporgenti, constituite della massa die uova. Tali riUevi non sono propriamente, nella linea mediana, 164 ILLINOIS BIOLOGICAL MONOGRAPHS [452 ma collocati a destra o a sinistra die essa formando in tal modo une striccia a zig-zag. L'aperture genitale maschile sbocca suUa faccia dorsale, e sulle opposta si apre I'utero. In alcune proglottidi I'ovario e bilobo, la uova sono ellissoidali e mancano di operculo." Liihe (1899:42-44) in defining the characters of the genus gave the general features of the genitaUa, while Ariola (1900:397) enlarged his own 1896 des- cription: "Ovario con numerose uova, talora bilobo; uova eUissoidaU aventi nel diametro longitudinale 67^1 e nel trasversale ?>2. ..." Braun (1900) reviewed the literature on the genus and species up to date, and Volz (1900) discussed the reproductive organs of the species as compared with those of his B. spiraliceps and the position of the openings in connection with brief remarks on the phylogeny of the genus Bothrioccpliahis s. lat. As regards his owti speci- mens Linton (1901:473) said that "Posterior segments show rudiments only of the reproductive organs, but no indication of external genital openings." And later Johnstone (p. 89) remarked that "the genital openings are in the middle Une of the proglottides but near the anterior borders of the latter, " referring evidently, as will be seen later, to the uterine openings only. The rudiments of the reproductive organs appear about three miillimetres from the tip of the scolex as aggregations of nuclei that can just be discerned in toto mounts (Fig. 48). About three millimetres farther posteriorly in mod- erately contracted older strobilas (such as would be obtained if no special care were taken during the fixation of the material) the cirrus and vagina are seen to be just piercing the dorsal surface. Before this region is reached, however, the common rudiment, at first circular and then elongated oval in outline, differentiates into a more anterior portion, the rudiment of the whole uterus, a more posterior less elongated part, the beginnings of the cirrus-pouch and vagina, and a third, connecting the other two near the hinder edge of the proglottis, the nuclear aggregation that will develop into the ovaries and the organs of the interovarial space (Fig. 74). As mentioned in the specific diag- nosis, the first tw^o of these rudiments alternate irregularly from side to side as do the corresponding adult structures. At the same time the testes and vitelline glands are developing in the medullary and cortical portions of the parenchyma, respectively. A distinct genital sinus or cloaca, the opening of which is usually almost circular in outhne, is present (Fig. 75). It varies from 0.05 to 0.09mm. in diameter and is situated, as above noted, nearly in the median line, dorsally, and from three-fourths to one-half the length of the proglottis from its anterior border, usually just posterior to the spurious articulations w^hen they are present. At the bottom of this sinus there is a secondary cloaca ("Gesch- lechstasche" or "Ductus hermaphroditious"), also circular in outline, from 15 to 25m in diameter, and into it open the cirrus and vagina quite close together, the latter immediately behind the former. This secondary sinus is best seen in sagittal sections (Fig. 103). The genital pore (the opening of the main sinus) is elevated slightly above the general dorsal surface of the proglottis, 453] PSEUDOPHYLLIDEA FROM FISHES— COOPER 165 thus appearing as a low cone or crater. No sphincters control the openings of either of these sinuses ])ut the cuticula of the floor of the larger or outer is modified to form coarse, low, rounded and closely set papillae which are evi- dently of special importance during copulation. These papillae would evidently serve to temporarily fasten the structure into the primary sinus of another proglottis, when it is possibly everted with the cirrus. Copulation was not observed in this species during life, nor were any cases of protruded cirrus met with in the material at hand. All of the proximal portions of the reproductive organs, excepting the vitelline follicles, are located in the medullary parenchyma, although the much distended uterus-sac, originally in the latter, extends almost to the cuticula on both the dorsal and ventral surfaces. Figure 75 shows their arrangement in toto. The testes are closely arranged in the medullary parenchyma in two lateral fields, each bounded laterally by the junctions of the dorsal and ventral layers of longitudinal muscles and medially by the other reproductive organs (except- ing the vitelline glands) vrhich occupy in the quadrate proglottides about the middle one-third of the transverse diameter of the strobila and are contiguous from joint to joint. In the quite mature elongated proglottides the testes are ellipsoidal in shape, averaging 0.125mm. in length by 0.040 in diameter, the cross-section being usually about circular in outline. In younger joints and in all those of much contracted strobilas the testes are nearly spherical in shape, measuring about 60/i in diameter, or often slightly longer than broad. They are arranged in a single layer in the medulla, the whole dorsoventral diameter of which they occupy, and are continuous from proglottis to proglottis. From 2 to 4 appear in each lateral field in transverse sections, from 5 to 7 are seen in sagittal sections between the posterior borders of consecutive proglottides, while, so far as could be determined from frontal series directly, the number is from 20 to 25. Thus each proglottis contains from 40 to 50 testes. The vas deferens forms a wedge-shaped mass of closely arranged coils, extending forv\'ard immediately ahead of the cirrus-pouch and alongside the uterus-sac for about two-thirds of its length (Fig. 75) . In proglottides in which the latter is yet comparatively small the vas deferens may pass forward as far as its anterior end. In either case it forms with the cirrus-pouch a mass which alternates from right to left with the uterus-sac. WTien distended with sperms the duct averages about 30/i in diameter; but just before it enters the cirrus-sac anterodorsally it narrows down to 5^. Immediately within the wall of the latter it often enlarges again to form a thin-walled functional vesicula seminalis, or perhaps more correctly ductus ejaculatorius, from 13 to 23/i in diameter. After one or two short turns it diminishes again to about 8/x and then passes on as the cirrus proper. While the proximal portions of the duct do not pass in any definite direction, the latter is situated for most of its length in the longitudinal axis of the pouch. It is about 0.10mm. in length and about 20 to 25)u in diameter at its middle. It is hned with a cuticula, lO^t thick, which is cleft but not armed with bristles of any kind. 166 ILLINOIS BIOLOGICAL MONOGRAPHS [454 The cirrus-sac (Fig. 103), situated immediately behind the uterus sac or lateral to its posterior end, is elliptical to slightly oval in outUne, and measures 0.128 to 0.162mm. long, 0.087 to 0.116 wide and 0.098 to 0.116 deep. The longitudinal axis is directed anterodorsally from the genital sinus and to the right or left, according as it alternates with the uterus-sac. The proximal one-third of the contents of the pouch consists of loose parenchymatous tissue with a few muscle fibres surrounding the ductus ejaculatorius, while the distal two-thirds, that part which accommodates the cirrus proper, is supplied mostly with muscles which actuate the latter. Large fibres proceed somewhat obli- quely from the wall towards the proximal pole of the sac to become broken up or frayed before they are attached to the cirrus tangentially, so as to give the appearance in frontal sections of the latter being surrounded by a com- paratively heavy layer of fine lightly staining circular fibres. A few of the fibres closest to the cuticula of the cirrus were considered to be true circular fibres; but no longitudinal fibres were seen. The wall of the cirrus-sac is from 2 to 3)u thick and is made up of very fine closely matted fibres, the direction of which could not be determined with satisfaction. The sac lies freely in the parenchyma of the region and is not connected by any special muscles to the dorsal or ventral body-walls; nor are the body muscles attached to it as in some cestodes. The layers of the latter are simply pierced and the fibres turned aside in evidently a passive manner. The opening of the vagina is close behind that of the cirrus at the bottom of the secondary genital sinus, or as it has been called by Fuhrmann, "ductus hermaphroditicus " (Fig. 103). From this point the duct courses ventropos- teriorly in the mid-Hne and then parallel to the dorsal surface of the proglottis until it reaches the ovarian isthmus, above which it makes a few turns and quickly diminishes from lOjj, in diameter half way along its course to 10/z. It then dips farther down into the genital space, often enlarging slightly as it does, and soon joins the oviduct at an enlargement of the latter situated a short distance behind the oocapt. Throughout its length it is lined with a ragged or pseudociUated cuticula and surrounded by radially arranged nuclei connected with the cuticula by cytoplasmic strands like those described by the writer for H. globuliforme (1914a:105) and considered to be possibly ex- truded nuclei of the original epithelium as well as the myoblastic nuclei of circular fibres, a layer of which surrounds the duct. There is no vaginal sphinc- ter. In his generic diagnosis Liihe states that the receptaculum seminis is small and in his description of the family Ptychobothriidae (1902:327) says that when present it is "in Gestalt eines kleinen BHndsackchens ausgebildet, welches parallel neben dem Endabschnitte des Oviduktes Kegt and mit der Vagina unmittelbar vor deren Vereinigung mit dem Ovidukt in Vergindung steht." On the contrary it was found to be a comparatively large structure but very difficult to orient in sections made in any direction. It is in the form of a thin-walled sac about 60 by 20)U, wrapped somewhat spirally around the dorsal waU of the above-mentioned enlargement of the oviduct and opening by an 455] PSEUDOPHYLLIDEA FROM FISHES— COOPER 167 aperture equal to its whole diameter into the vagina just at its juncture with this vestibule. But since the vagina constantly constricts a second time to a diameter of about 8^1 before entering the latter, one gets the impression of the receptaculum seminis being a diverticulum of the oviduct rather than of the vagina. Figure 108 of four consecutive sections of a transverse series, showing the union of these ducts, will give a better idea, perhaps, of the nature of the seminal receptacle. In mature proglottides the ovary (Fig. 90) is a bilobed structure situated in the median line, close to the posterior border of the proglottis and immediately ahead of the uterus-sac of the proglottis follo^ving, where the latter is much dis- tended with eggs (Fig. 75). In toto mounts the lobes seem to be quite separate from each other, but in sections the isthmus is easily made out. It occupies the ventral half of the medulla v.'hile the v^ings or lobes extend completely across the space between the layers of longitudinal body muscles. The lobes are about 0.27mm. long by 0.13 wide, while the isthmus is 0.06 to 0.08m-m. in anteroposterior diameter. These proportions are, however, much different in much contracted strobilas or in proglottides in which the uterus-sac is dis- tended with eggs. In both instances the ovary is very much flattened antero- posteriorly and, in the latter case, all but obUterated, as shown in Liihe's figure 8 (1902:326). The ova from that portion of the isthmus where they are ready to be passed on by the oocapt, are elliptical to oval in outUne in sec- tions and measure on the average 18 by lO^i, their nuclei being about 9/i in diameter. The oocapt, situated in the median line at the posterior border of the ovar- ian isthiTiUs, somewhat dorsally, is a spherical to ovoid muscular organ about 20/i in diameter (Fig. 103). Immediately behind it the oviduct constricts to a diameter of only 7 to lO/x and then passes on posteriorly and ventrally either to the right or to the left, gradually enlarging until the above-mentioned vesti- bule is reached, vvhen the diameter is 25 to 30/i. The latter enlargement is less of the nature of a direct continuation of the oviduct than a more or less separate thin-walled structure — the walls of the oviduct up to this point being comparatively thick (Fig. 108) — into which the oviduct opens by a sUghtly elongated aperture. While the wall of the first portion of the oviduct consists of more or less cubical ciliated cells with somewhat indefinite boundaries — ordinarily they stain very densely — that of the vestibule shows only a few scattered nuclei protruding into the lumen. The oviduct continues postero- laterally and ventrally from one corner of the vestibule (that with which the vagina is usually connected) as a tube quickly diminishing from 15 to 10/x in diameter and lined with a ciliated epithelium with prominent nuclei but no distinct cell -boundaries. Close to the anterior wall of the uterus-sac of the succeeding proglottis it turns upward sharply and at about the middle of the dorsoventral diameter of the m.eduUa takes on the vitelline duct. It then skirts the uterus-sac, just mentioned, as it passes to the opposite side of the generative space and slightly forward, to soon become surrounded by the shell-gland. 168 ILLINOIS BIOLOGICAL MONOGRAPHS [456 The vitelline duct at its union with the oviduct has a diameter of S^t; but just beyond this, in the direction of the follicles, it soon enlarges to form a somewhat irregular vitelline reservoir which when filled with yolk may attain a diameter of 30^. Its general course is towards the opposite side of the generative space almost parallel to either surface of the body; but beyond this it could not be traced with satisfaction. The vitelline folUcles fill up almost the whole of the cortical parenchyma from the layer of longitudinal body muscles to the nuclei of the subcuticula, the thickness of the stratum averaging 0.05mm. (Fig. 90). They form a con- tinuous layer around the margins of the proglottides (in transverse sections) and also from proglottis to proglottis, as mentioned above, even extending well into the posterior borders. They are not arranged in lateral fields, but are interrupted only where the uterus sac and genital sinus pierce the body- wall, or in the former case greatly press against the latter. The individual follicles attain a size of 60^ and are very closely crowded together. The number in cross-sections of the proglottis averages 55 and in sagittal sections 13, thus making the average total number for each proglottis 715. The shell-gland is situated in the dorsal portion of the genital space, that part of the oviduct showing the connections being almost horizontal in position and about 18m in diam.eter, that is, a little larger than the oviduct behind that region. The individual cells of the gland are much attenuated, closely ar- ranged and have their nuclei situated in their sUghtly enlarged distal ends. Their connections wdth the oviduct give the wall of the latter a honeycombed appearance when it is seen in longitudinal section. Beyond this region the oviduct gradually enlarges as it passes above the ovarian isthmus to become the uterine tube, the coils of which are accommo- dated opposite the cirrus pouch just behind the uterus-sac. As it proceeds its wall gets thinner and the nuclei protrude more and more into the lumen until many of them are evidently lost. It is noteworthy that the uterine tube in many cases as well as the uterus -sac, especially in younger proglottides, alternates irregularly from right to left according as the cirrus and vas deferens do. These three structures are, in fact, fitted very nicely into the space be- tween the uterus-sac ahead and the ovarian isthmus behind. The uterus-sac is elliptical in outUne, has its longitudinal axis directed anteroposteriorly, and is situated in the anterior half of the proglottis. In very mature segments it occupies almost the whole of the meduUary region, or to be more precise, the middle three-fifths of the diameter of the proglottis, its anterior end extending forward close to the ovary of the proglottis immediately ahead (Fig. 75). Luhe (1902a:326) figured the uterus as, to use his own words, "... in der Kegel eine geraumige Uterushohle bildend, welche die iibrigen Genitalorgane, ohne dass freilich deren Riickbildung eintritt, buchstablich an die Wand drangen kann. indem die ganze Proglottis in reifen Proglottiden vielfach als ein einziger sackformiger Eibehalter mit verbal tnisstnassig sehr diinnen Wandungen erscheint. " But such a degree of restriction of the other genitalia was seen by the writer only in a few of the ripe proglottides of strobilas 457] PSEUDOPHYLLIDEA FROM FISHES— COOPER 169 much contracted longitudinally. There the largest uterus-sac measured 0.8mm. wide by 0.67 long, while the width of the proglottis in question was, at the posterior borders of the spurious articulations, 1.57mm. In fairly re- laxed strobilas it increases in dimensions from 0.18 by 0.14mm., where the first eggs appear in the lumen, to 0.87mm. long by 0.48mm. wide, where the proglot- tis is 0.80mm. wide at its middle, in the latter case, of course, pressing against the dorsal and ventral walls even as far as the cuticula. From a comparison of these measurements, and the further fact that in the case of the former much contracted strobilas there often appears, behind the region showing the nearly obhterated genitaha, a more relaxed one in which the relations of the uterus-sac to the other organs is quite as in the competely relaxed strobilas, one is inclined to conclude that the characters of the family above quoted apply to this species only in the case of proglottides much contracted longitu- dinally. In the quadrate proglottides the smaller, that is, younger sacs alter- nate irregvilarly from right to left, as do the uterine openings, and according as the cirrus pouch and the vas deferens in particular (on account of its above- mentioned position) occupy the opposite sides of the proglottis. Externally, in alcohohc specimens, the uteri appear as a gradually enlarging series of brown punctations caused by the contained eggs showing through the thiimed body wall, as pointed out originally by Rudolphi and other writers. The wall of the uterus consists of a thin membrane on the inside of which a very few scattered and somewhat flattened nuclei indicate its original epi- thelial nature. In young proglottides, where no eggs are to be seen in the small uterine cavities, the wall is composed of an epithehum about 8/i thick, showing prominent nuclei but no distinct cell-boundaries. Furthermore in such early stages the lumina of the uterine ducts, developing in the manner described by Young (1913) and Shaefer (1913)^ are not completely formed nor in connection with the cavities of the sacs, but the uterine apertures are promi- nent. In the first two or three sections of a lOn frontal series, taken from the ventral surface, they appear as distinct somewhat elliptical apertures about 26m in transverse diameter, but in the third or fourth section are closed, only to reopen as the cavity of the uterus-sac, thus showing that the membrane closing the aperture is only about 10^ in thickness. And this closed condition is maintained until the uterus-sac attains the above-mentioned maximum size and becomes greatly distended with eggs. Then the functional opening is estabUshed by the rupture of the membrane which has meanwhile reached a length of 0.046 to 0.058mm. by a width of 0.034 to 0.046, its elliptical outhne thus having been retained. The opening does not become as regular in outhne, however, as the membrane, for the latter remains around the rim as ragged processes, which render the determination of the exact location of the aperture in toto mounts a matter of no little difficulty. The uterus openmg is sur- rounded by a series of radiating cells like those of the opening of B. scorpli described above. The fresh eggs examined in saline solution are elliptical to ovoid in shape, 75 by 40m in dimensions and provided with a thin, very Ught brown shell hav- 170 ILLINOIS BIOLOGICAL MONOGRAPHS [458 ing no operculum. The color is so faint that it can be seen to advantage only when the eggs are in masses or in the uterus-sac. Ariola (1900:397) gave the measurements of the eggs of the European species as 67 by 32ju. The larg- est examined were immature, the contents consisting of large spherical cells only, like those shown by Wagener (1854a) in his figure 6, Taf. I. When the worms are stiU attached to the waU of the intestine of the host between the mucous folds, they often discharge many of their eggs from most of the posterior proglottides when their scoUces are irritated with a blunt needle in order to make them loosen their comparatively firm hold. Forty-four specimens of Merluccius bilinearis were examined at Woods Hole and at Harpswell, but no definite idea of a possible intermediate host was obtained. It was noticed, however, that when the intestine of the fish con- tained much grey chyle, presimiably the result of the digestion of small her- ring— definitely ascertained at South Harpswell to be such in a few cases- and of Pomolobus aestivalis (Mitchill), the blueback — no tape-worms of this species were present; but where amphipoda were found in the stomach or the remains of such in the intestine the worm was plentiful. Furthermore, where nothing was found in either stomach or intestines, other than yellowish chyle in the latter — as in most fish examined — indicating amphipods and other small crustaceans as food rather than small herring, the worm was also common. AU stages from the youngest strobilas, such as that shown in figure 49, to the oldest were found, but none nor any plerocercoids were met with in the course of the thoro dissection of the available stomach contents of the hosts, both fish and crustaceans. In a number of cases, nevertheless, only very young strobilas were found in the intestine of the host, thus pointing to possible sudden infections at different times. Wagener, who figured the youngest strobila that has yet been recorded, in fact nothing much more than the scolex, said nothing more concerning the fife history than that, on account of the ex- cretory vessels opening separately to the exterior in this very young specimen, there might possibly have been a vesicular appendage to the larva in the nature of an enveloping cyst comparable to that described and figure for "Dibothrium. (Belones?) " from Scyllium canicula, concerning which he said (I.C., p. 45): "Vergleicht man diese Form vom Cysticercus mit den vorigen [Cysticercus fascicolaris Rud.], so ergiebt sich, das der Unterschied nur in dem Aufhangebeutel sich findet, der Kopf und Blase verbindet. " A detailed description of the species is here given, not only because it is evidently the only one belonging to the genus, but because descriptive details are so lacking from the European hterature that the determination of the spe- cies is attended with considerable uncertainty. The writer, however, considers that, on the basis of the pubhshed accounts and reports of the species, but in the absence of European material for comparison, the form occurring on this side of the Atlantic Ocean must be looked upon as identical with the C. crassiceps of Europe. The material studied consisted of No. 204, 259, 261, 262, 269, and 282 in the writer's collection from the intestine of Merluccius bilinearis as above listed. 459] PSEUDOPHYLLIDEA FROM FISHES— COOPER 171 AMPHICOTYLINAE Liihe 1902 Scolex with two typical, usually not very deep bothria, which in some forms develop posterior, sucker-like portions. In an isolated case a pseudo- scolex is substituted for the scolex. External segmentation insignificant, at times disappearing thru accessory wrinkling or folding of the surfaces of the proglottides. Opening of cirrus and vaginal marginal, irregularly alternating, with more or less strongly pronounced tendency to unilaterality. Uterus- opening median; uterus-sac always well developed. CoiUng of vas deferens strongly expressed. Occurrence: In fishes. Type genus: Amphicotyle (Diesing 1864) Ariola 1900, e.p. Luhe 1902. ABOTHRIUM van Beneden 1871, char, emend. Liihe 1899 Taenia (part.) Auctorum Rhytis (part.) Zeder 1803 Bothriocephalus (part.) Rudolphi 1809 Bothriocephalus (part.) Rudolphi 1819 Bothriocephalus (part.^ Leuckart 1819 Dibothrium (part.) Diesing 1850 Bothriocephalus (part.) Baird 1853 Dibothrium (part.) Diesing 1863 Bothriocephalus (part.) Olsson 1867 Abothrium Beneden 1871 Abothrium Moniez 1881 Dibothrium (part.) Linton 1890 Abothrium Lonnberg 1891 Bothriocephalus (part.) Matz 1892 Bothriotaenia (part.) Ariola 1896 Bothriotaenia (part.) Riggenbach 1896 Abothrium Liihe 1899 Bothriotaenia (part.) Ariola 1900 Abothrium Liihe 1900 Abothrium Liihe 1910 Scolex not exceptionally elongated, with two powerful but not especially deep bothria. Segmentation in older portions of the strobila usually insigni- ficant on account of superficial wrinkling of the individual proglottides; ripe proglottides essentially broader than long. Longitudinal nerves near the lateral borders, dorsal to the cirrus-sac and vagina. Testes exclusively be- tween the nerve strands. Vitelline foUicles of very irregular shape, in two broad lateral fields, in part at least between the bundles of the longitudinal muscles, the follicles of individual proglottides not especially separated from one another. Ovary scarcely lobed, m.ore or less bean- or kidney-shaped. Shell-gland dorsal to the ovary. Uterus-sac in ripe proglottides occupying the whole of the medullary parenchyma. The openings of the uteri correspond to a more or less prominent m.edian longitudinal furrow of the chain of proglot- tides. Type species: A. rugosum (Batsch). 172 ILLINOIS BIOLOGICAL MONOGRAPHS ABOTHRIUM RUGOSUM (Batsch 1786) [Figs. 32-36, 63, 76, 91, 109] [460 1773 Taenia dccimpoUicaris Strussenfelt 1773 :27 1781 Taenia tetragonoceps (part.) Pallas 1781 :88 1782 "Der runzlichter Fischbandwurm " Goeze 1782 :410 178^ Taenia rugosa Batsch 1786 :208 1788 Taenia tetragonoceps (part.) Schrank 1788 :46 1790 Taenia rugosa Gmelin 1790 :3078 1802 Taenia rugosa Rudolphi 1802 : 107 1803 Rhytis conoceps Zeder 1803 :292 1810 BoihrioccphaJus rugosus Rudolphi 1810 :42 1816 Bothrioceophalus rugosus Lamarck 1816 :168 1819 Bothriocephahts rugosus Rudolphi 1819 :137 1819 Bothrioccphalus rugosus Leuckart 1819 :57 1845 Bothriocephahis rugosus Dujardin 1845 :618 1850 Dihothrium rugosum Diesing 1850 :591 1853 Bothriocephahis rugosus Baird 1853 :88 1863 Dihothrium rugosum Diesing 1863 :239 1867 Bothrioccphalus rugosus Olsson 1867 :53 1871 Ahothrium gadi Van Beneden 1871 :56 1881 Abothrium gadi Moniez 1881 :167 1889 Bothriocephahts rugosus Linstow 1889 :242 1889 Bothrioccphalus rugosus Monticelli 1889 :68 1890 Dihothrium rugosum Linton 1890 :750 1890 Abothrium rugosum Lonnberg 1890 :22 1891 Abothrium rugosum Lonnberg 1891 :75 1892 Bolhriocephalus rugosus IMatz 1892 :113 1894 Bothriotaenia rugosa Blanchard 1894 :701 1896 Bothriotaenia rugosa Ariola 1896 :280 1896 Bothriotaenia rugosa Riggenbach 1896 : 223, 228 1898 Bothriotaenia rugosa Muehling 1898 ; :35 1899 Abothrium rugosum Liilie 1899 ; :39 1900 Bothriotaenia rugosa Ariola 1900 : ;432 1900 A bothrium rugosum Liihe 1900a :101 1901 Dihothrium rugosum Linton 1901: 412,476 1903 Bothriotaenia rugosa Schneider 1903 : :7 1910 Ahothrium rugosum Liihe 1910 : :26 Specific diagnosis: With the characters of the genus. Large cestodes with maximum length, breadth and thickness of 1000, 7 and 2inm., respectively. Scolex present only in very young strobilas, when conical and provided with very weak bothria, changing with age to a pseudoscolex of various shapes, usually imbedded in pyloric cecum of host. Proglottides at first broad and ver>' short, obscured by irregular transverse and longitudinal rugae, then gradually lengthening with age until finally quadrate or longer than broad, Cuticula 5m thick, subcuticula 0.14mm. Small calcareous bodies, 20ju in length. Longitudinal muscles in bundles, transverse forming septa between proglottides. Nerve strands 45^1 in diameter. Two chief excretory vessels anteriorly, passing into 30 to 35 posteriorly. Genital cloaca irregularly alternating, between first and second thirds of edges of proglottides. Vagina opens immediately behind the cirrus and slightly ventral; no hermaphroditic duct. 461] PSEUDOPHYLLIDEA FROM FISHES— COOPER 173 Testes discontin-uous from proglottis to proglottis, ellipsoidal, flattened anteroposteriorly, 40 by 90 by 85^, and 45 to 60 in number. Vas deferens lateral to uterus-sac with few coils before entering the cirrus-sac, 350 by 70 to 80/x. Cirrus-sac ovoid with narrow end outward, 174 to 277// long by 92 to 102ju in diameter. Cirrus straight in outer half of sac, proxunally coiled or dilated. Ovary large, entire, kidney-shaped (isthmus as thick as the wings), 0.6mm. wide, occupying the posterior half of the median portion of early mature seg- ments. Ova conspicuous, nuclei large, 10 to 13ju in diameter. Oocapt 34fj, in diameter. Beginning cf oviduct S-shaped. Right and left vitelline ducts join ventrally; common duct acts as reservoir. Vitelline follicles entirely within longitudinal muscles, discontinuous, intermingling laterally with the testes, irregular in shape and size, largest 30, 90 and 70/i in length, width and thickness, respectively. Shell-gland compact. Uterine duct with only a few coils close to the median hne; uterus-sac very wide and short, or irregularly circular or quadrate surficially, often lobed, 0.75 to 1.6mm. in transverse dia- meter, constantly rounded laterally; openings in median zig-zag row. Eggs, 80 to 98ju long by 75 to 92/i wide, shell quite transparent. Habitat: Intestine of the host with pseudoscolex imbedded in a pyloric coecum. HOST LOCALITY COLLECTOR AUTHORITY Borke Goeze 1782 : 410 Cinfiti^ tyii4'\fpl fi Wagler Goeze 1782 :411 Gadus aeglifinus Warberg Olsson Olsson 1867 : 54 Gadus aeglifinus Bergen Lonnberg Lonnberg 1890 : 22 Gadus aeglifinus Grafverna and Naset Olsson Olsson 1893 : 17 Gadus aeglifinus Arctic Ocean Zool. Mus. d. K. Akad. Wiss., Petrograd Lin stow 1901 : 281 Gadus aeglifinus England Nicoll Nicoll 1907 : 71 Gadus callarias Woods Hole, Mass. V. N. Edwards Linton 1898 : 431 Gadus callarias Arctic Ocean Zool. Mus. d. K. Akad. Wiss., Petrograd Lin stow 1901 : 281 Gadus callarias Murman-Kiiste Zool. Mus. d. K. Akad. Wiss., Petrograd Linstow 1903 : 19 Gadus callarias Nokujev Id., Arctic Zool. Mus. d. K. Akad. Wiss., Petrograd (Baer) Linstow 1903 : 19 Gadus lota Greiphswald Rudolphi Rudolphi 1810 : 43 Gadus merluccius Rennes, France Dujardin Dujardin 1845 : 617 Gadns morrhua Warberg Olsson Olsson 1867 : 54 Gadus morrhua Grand Banks, Newfoundland Lee Linton 1890 : 750 174 ILLINOIS BIOLOGICAL MONOGRAPHS [462 HOST LOCALITY COLLECTOR AUTHORITY Gadus morrhua Bergen Lonnberg Lonnberg 1890 : 23 Gadus pollachius Rennes Dujardin Dujardin 1845 : 617 Gadus pollachius Warberg Olsson Olsson 1867 : 54 Gadus pollachius Bergen Lonnberg Lonnberg 1890 : 22 Gadus pollachius Grafvema & Naset, Sweden Olsson Olsson 1893 : 17 Gadus pollachius Millport, Scotland NicoU NicoU 1910 : 355 Lota vulgaris Lota vulgaris Siebold Baird 1853 : 89 Memel and Muehling Muehling 1898 : 35 Rossitten Lota vulgaris Tvarminne Id., Finland Schneider Schneider 1903b : 8 Morrhua aeglifinus England Cobbold Cobbold 1858 : 158 Morrhua vulgaris England Cobbold Cobbold 1858 : 159 Morrhua vulgaris Belgian coast van Beneden van Beneden 1871 : 56 Merlangus carbonarius England Cobbold Cobbold 1858 : 159 Merluccius vidgaris Warberg Olsson Olsson 1867 : 54 Melanogrammus aeglifinus Woods Hole Sumner, 1913 : 586 Region Osbom and Cole Microgadus tomocod Woods Hole Sumner, 1913 : 586 Region Osbom and Cole Urophycis tenuis Woods Hole Region Snmnpr 19n • '^86 Osborn and Cole Melanogrammus aeglifinus Passamaquoddy Cooper Cooper Bay, New Bruns. (the present paper) Melanogrammus aeglifinus Bay of Fundy, Cooper Cooper Campobello Id. (the present paper) Melanogrammus aeglifinus Freeport, N. S. Cooper Cooper (the present paper) Gadus callarias Campobello Id. Cooper Cooper (the present paper) Gadus callarias Woods Hole V. N. Edwards Cooper Region (the present paper) This species was first described by Goeze (1782:410) under the name of "Der rimzUchter Fischbandwurm " and not as Taenia rugosa, as indicated by many later writers, including such authorities as Liihe, Braun and Ariola. It was Batsch (1786:208) who gave the specific name on the basis of Goeze's description. The latter, in fact, in a foot-note (p. 410) accepted Pallas' T. tetragonoceps to be synonymous with the forms he studied, at least in part, since he recognized that they were at the same time unlike those figured by Pallas after Bloch, from the " Madui-morane " and the " Rheinlachs. " It remained for Rudolphi (1810:42) to give a somewhat more detailed description, which seems to have been accepted by Diesing (1850, 1863) and others, altho Dujar- 463] PSEUDOPHYLLIDEA FROM FISHES— COOPER 175 din (1845:617) and Cobbold (1858:158) made important additions to the knowledge of the species. Van Beneden (1871:56) erected the new genus, which was later accepted by Lonnberg (1891:75) who used his specific name gadi as synonymous with the B. rugosus of the earlier writers. Fraipont (1880:267; 1881:12) added to the knowledge of the excretory system. It was not until some time later, however, that Linstow (1889:242) essayed to give a more detailed description of the whole worm, while Lonnberg (1891 :75) and Matz (1892:113) by their attention to the anatomy, especially of the re- productive organs, laid the foimdation upon which all the writers since have based their conceptions of the species. While the development, especially in its earhest stages, was studied by Schauinsland (1885:527), and later by Saint-Remy (1900:296), the systematic position has since then been dealt with by Blanchard (1894:701), Ariola (1896:272, 274; 1900:432), Riggenbach (1896:223) andLiihe (1899:33; 1900a:47, 96, 101; 1910: 26). Linton (1890:750; 1898:431) is the only writer who has described the species in America. The dimensions of the species are, according to Liihe (1910:26), 400mm. to 1 meter in length by 2 to 5mm. in maximum breadth; whUe Ariola (1900: 433) gave the total length of the strobila as from 16 to 97cm. Linton (1890: 751) worked with specimens from the cod, the largest of which measured 655mm. in length by maximum breadth and thickness (posteriorly) of 6 and 2mm., respectively. The largest studied by the writer was a fairly contracted one (No. 301, below) from Gadus callarias, 416mm. in length by 7mm. in maxi- mimi breadth 100mm. from the incomplete posterior end and 5mm. at the posterior end. As the names used by Goeze, Batsch and Rudolphi indicate, this species is characterized by its transverse wrinkles or folds, often irregular and compli- cated by longitudinal grooves and folds anteriorly but regular and correspond- ing to the internal segmentation posteriorly, and by the general tumid appear- ance of the strobila due to the very large uterus-sacs gorged with eggs. But most striking of all is the presence of a pseudoscolex which is found embedded in the intestinal coeca or intestinal wall of the host, from which it is extracted only by careful dissection. Goeze (1782:412, Figs. 1, 4 and 5) described a scolex, somewhat elongated, sagittate and irregular but otherwise comparable to that of other bothriocephalids, while Rudolphi (1810:43) does not seem to have found anything of such a structure in Gadus lota. Dujardin (1845: 617) was evidently the first to describe the pseudoscolex by saying that, "... la partie anterieure [of the strobila] engagee dans I'appendice pylorique forme una sort de bouchon, un cyhndre irregulier, cartilagineux, long de 18min., large de 4mm., ride ou toruleux et sans ancune trace d' organisation ..." This description, however, was not recognized by Diesing (1850:590), but he accepted Rudolphi's diagnosis, namely, "Caput subsagittatum, bothriis oblongis laterahbus. ..." Baird (1853:89) evidently saw two bothria, probably owing to the fact that he was dealing with specimens from Lota vulgaris (vide infra). Cobbold (1858:158, 159) was well acquainted with the pseudoscolex, since regarding individuals from the cod ("Morrhua vulgaris'') 176 ILLINOIS BIOLOGICAL MONOGILAPHS [464 he said "In a cod examined on the 15th of March, 1885, two specimens of Bothriocephalus rogosus had severally attained a length of nearly fifteen inches, and their anterior segments for an inch or more downwards, were so firmly impacted within the pancreatic coeca, that it was found impossible to dislodge them without injuring the filamentary head and neck. As if to make the anchorage doubly sure, the cartilaginous thickening of the invaded pancreatic coecum had degenerated into a calcareous and contracted cylinder, twisted upon itseK in various ways." Olsson (1867:54) likewise found a pseudoscolex in this species, which he described as being degenerated in Gadus morrhua to a yellow, elongated m^ss which disintegrated on contact with water. It was 18 to 25mm. in length by about one-half a millimetre in diame- ter, while its position was, as usual, in the wall of a pyloric appendage of the host. He also figured a young strobila from Gadus aeglifinus, the scolex of which he considered to have been invaginated. In his new genus and species, Abothrium gadi, van Beneden (1871:56) observed the pseudoscolex stating that "Us ont la tete vers le fond des coecums pyloriques, percent ordinaire- ment les parois et forment, par la gaine, souvent dure et entortillee comme une tabulaire, mie saiUie a la surface de cet organe. " So far as the writer is aware, he gave the first figure of the structure, as it is commonly met with, encased, however, by the walls of the pyloric coecimi in which it was found lodged. Von Linstow (1889:242) described and figured a scolex somewhat similar to that of A. crassum, excepting that the apex was hollowed out to form a six- cornered opening which communicated with both bothria. Linton (1890: 750) foimd pseudoscolices in examples from the codfish, "Gadus morrhua," which were much as described by Olsson, since he said that "each of the specimens in this lot has the head and anterior part of the body buried in the pyloric caeca, where they have undergone degeneration to such an extent that no appearance of bothria remains. Around the parts thus enveloped by the caeca is a yellowish waxy deposit, the degenerated tissue of the caeca. This adventitious tissue invested the worm so closely that it would be absolutely impossible for the parasite to free itself from its host." The next important reference to the scolex was by Lonnberg (1891:75) who, while accepting van Beneden's new genus, Abothrium, referred the species back to rugosum of Batsch, and described the metamorphosis of the anterior end of the strobUa into the well -kno"v\Ti pseudoscolex, accoimting for the various forms, such as figured here. It is noteworthy, however, that he did not state specifically that bothria are present in very young scolices, before this transformation takes place, nor did he give any figures to illustrate the latter. Matz (1892: 114) described and figured a typical scolex for a specimen 36cm. long from Lota vulgaris, while Schneider (1903a:9) in delineating a similar structure for the species from the same host, pointed out its great similarity to the scolex of B. proboscideus { = A. crassum). Perhaps of significance in connection with the question of the metamorphosis of the organ is his statement that "Der ganze Scolex kann sich namlich durch verschiedene Contraction seiner Mus- keln in ein pfeilformiges, oder fast cubisches, oder sogar sichelformiges GebUde 465] FSEU DOPE YLLI DBA FROM FISHES— COOPER 177 verwandeln. " Later Johnstone (1907:170) described the pseudoscolex with considerable detail, finding quite the same conditions as did Linton. On ac- count of never meeting with anything like a typical scolex in adult worms he was led to conclude that "Probably in young codling, recently infected, a stage of the cestode with such a scolex might be found but doubtless with in- creasing age the changes mentioned above occur, and the normal structure of the head disappears. " And lastly, Scott (1909:85) made somewhat similar statements, pointing out that " ... no satisfactory description of this part of the worm [the pseudoscolex] has yet been pubUshed." Thus it is seen that, apart from Olsson's (1867:54) finding in Gadus aeglifinus of a possible young stage in the degeneration of the scolex of this species, no one has, as yet, figured in detail its metamorphosis, Lonnberg, however, giving the only description of the process. On the other hand, a typical scolex has been des- cribed by several writers, as pointed out above, for what has been taken to be the same species in Lota vulgaris, but since there is evidence that the latter is quite different from the species found in marine Gadidae and since the speci- mens from Lota maculosa, studied by the writer, were found to belong to the well known A. crassum, a pseudoscolex must be attributed only to adults of A . rugosum, at least until the confusion which exists in the hterature regarding the form from Lota can be cleared up by further investigation. Two forms of pseudoscolex which were dissected out by the writer from the pyloric ceca of Melanogramnius aeglifinus, the haddock, and Gadus callarias, the cod, are shown in figures 35, 36, respectively, the latter being from the largest specimen at hand; while what is doubtless a younger stage in the degeneration of the scolex is shown in figure 34 from the intestine of a had- dock. A series of transverse sections of the latter, brought out that the inter- nal anatomy was quite suggestive of a typical scolex, that of A. crassum, for example. As shown in the figure, the structure is somewhat flattened in the dorsoventral direction. While there were only faint suggestions of bothria, especially towards the tip, the arrangements of the muscles, nerves and ex- cretory vessels pointed to its being possibly not far removed from the typical form of scolex. This view is supported by the fact that it was found free in the anterior part of the intestine of the haddock, altho, unfortunately, the length of the strobila was not recorded. Among a lot of material taken from several haddock two examples of the true scolex, as it would seem to be at or about the time degeneration sets in, were found. The first one, shown in figure 32, was from the smallest strobila at hand, 22mm. in length, while the other, figure Z3, was from an older chain, only the anterior end of which was present with a length of 32mm. and maximum breadth of 2.5. The second is evidently the older from the standpoint of metamorphosis, since it is more conical and less separated from the neck region which is slightly swollen; while the bothria are disappearing as the whole structure is approaching the stage repre- sented by figure 34. In figure 32 are seen somewhat more efficient bothria, but the shape of the organ points to a considerable amount of degeneration having already taken place. The next stage in the degeneration of the scolex 178 ILUNOIS BIOLOGICAL MONOGRAPHS [466 is represented by figvire 35. Here the structure is likewise not embedded in the wall of the pyloric cecum in which it is found but free in its lumen, the anchorage for the strobila being obtained by the close approximation of the mouth of the cecum around the narrow neck region and the concomitant swelling of the more distal portions. Furthermore, the indications are that a considerable portion of the anterior end of the strobila is involved in the formation of the organ, especially since it is comparatively large. The final stage is that shown in figure 36, where degeneration has gone on to such an extent that there remains only a filamentous, homy or cartilaginous yellow mass, deeply and firmly embedded in the wall of the cecum. Only the tip is shown, there having been about 6mm. more to the region where it left the host tissues and passed insensibly on to the anterior portion proper of the strobila. The latter showed only faint transverse wTinkles and no distinct division into segments, as is seen, with some irregularity, however, in figure 32. This form of pseudoscolex was found, as described by Olsson, Linton and Johnstone, to be surrounded by the tissue of the cecimi degenerated to a yellow waxy mass which, when freed from the surrounding tough tissue, crimibled easily under the dissecting instruments. The strobila, at first almost cylindrical in shape, gradually becomes wider and more depressed until the maximum breadth near the posterior end is at- tained. As regards the form of the segments Dujardin said that, " . . . le reste du corps long de 100 a 140mm., large de 2mm. en avant et de 6.5 en arriere, est libre dans I'intestin et forme d'articles tres coittts, inegaux ou dilates ca et la; . . ."; and Linton stated that, "The body is not dis- tinctly segmented at first, but is crossed by innumerable fine wrinkles. " WTiUe the latter statement is in the main true, and applies particularly to the youngest strobilas, many species show that these rugae, altho much obscured by irregular longitudinal grooves, are simply due to the formation of extremely short seg- ments which correspond proportionately with the much more distinct ones farther back. These segments gradually elongate as they pass backward imtil the end proglottides are often quadrate or even longer than broad, depend- ing on the degree of contraction or relaxation. Linton gave the length of the segments near the middle of the strobila as from 0.7 to l.Omm. and posteriorly 0.45, and the thickness as 2mm. The latter was 2.5mm. in the largest speci- men examined by the writer. The openings of the uteri on the ventral surface of the strobila form collectively a sort of shallow groove, more pronounced, of course, posteriorly but quite obMterated when the segments are considerably relaxed. The anatomy of the species was first given careful attention by Linstow (1889:235). Later Lonnberg (1891:75) and Matz (1892:113) pubhshed more accurate descriptions to which most of the writers since have referred. That of Lonnberg was found, however, to be most applicable to the material at hand from the cod and the pollack, for Matz was dealing with specimens from Lota vulgaris and Linstow apparently confused the two possible species from Lota and the marine Gadidae {vide infra). 467] PSEUDOPHYLLIDEA FROM FISHES— COOPER 179 Linstow included in his conception of the cuticula not only the cuticula proper, which he stated was ?>.Zn in thickness, but also the outer clear zone of the subcuticula which he found to be 49/i thick. In the present study the cuticula was found to be about Sju thick and to be divided into the three zones described by Lonnberg; viz., an outer pseudociUated or ragged layer, occupying almost one-half of the thickness of the whole membrane, a middle homogeneous principal stratum, and an innermost basement membrane which stands out quite distinctly in this species without the use of any special stains. The sub- cuticula was found to average 0.14mm. in thickness, the clear outi'r ends of the elongated cylindrical and closely crowded cells being collectively 23)U thick. The whole cortex in transverse sections has a depth of 0.32mm. Small cal- careous bodies, quite difficult to distinguish from parenchymatous nuclei, are present as described and figured by Lonnberg. They are oval to elliptical in outline and have a maximum length of IQy.. The musculature is well developed, and is peculiar in that the sagittal fibres especially retain their myoblasts, which are very easily recognized in sections. "They extend from the dorsal to the ventral surface and are usually attached to the cuticula with their ends, but often fasten on to the walls of the excretory vessels or other organs. Their number rises considerably with increasing age of the proglottis. Since they pass thru the spaces between the bundles of longitudinal muscles, they are partially arranged in fasicles. These muscles have not only a nucleus, but often also surrounding the same a quite large, spindle-shaped protoplasmic mass; and one easily finds the different develop- mental stages from a spindle-shaped cell to fully developed muscle fibres of typical appearance, where the protoplasm is already transformed and reduced, and only the nucleus persists. " They are only slightly more numerous between the sets of reproductive organs than elsewhere. In tliis region, on the other hand, the transverse series form, as emphasized by Lonnberg, a distinct parti- tion separating all constituents of the genitaha of successive proglottides,the testes and vitelline follicles especially (cf. A. crassum). In transverse sec- tions they form a "plate," bounding the medulla externally on each surface, from which a few fibres pass farther out among the bundles of longitudinal mus- cles. The latter are arranged in two distinct layers, each about 0.15mm. in thickness in the median line, which gradually diminish towards the edges of the strobila where they join thru several small and very irregular bundles. These larger fasicles are further subdivided dorsoventrally into smaller ones of various sizes, aU of which are connected longitudinally, however, by strands passing from one to the other, as pointed out by Lonnberg. In the anterior end of the strobila, as one foUows them forwards, the fasicles of longitudinal fibres become less and less distinct, but extend to the tip of the scolex, or young pseudoscolex, as the case may be, scattering considerably as they go. In sections thru the structure shown in figure iZ, a small number of sagittal and transverse fibres and a very few radial ones, situated between the grooves seen externally proves that it is a scolex, but a poorly developed one, or, as indicated above, one showing early stages in the process of degeneration to form the 180 ILLINOIS BIOLOGICAL MONOGRAPHS [468 pseudoscolex. This latter statement applies in a greater degree to the struc- ture shown in figure 34, since in it still more degeneration is present to the extent that no traces of the radial fibres are to be seen altho there are very shal- low bothrial depressions. In each case there appears in the medulla and among the longitudinal muscles near the tip of the organ a considerable amount of a material which takes the Orange-G counterstain very readily. While this is relatively more abundant in the older of the two pseudoscohces in question and intermingled with a good deal of calcareous material, it is confined more lo the very tip of the younger organ. It represents possibly the first stages in the development of the yellow homy material seen in the oldest and most degen- erate pseudoscohces. Each of the chief nerve strands has a diameter of about 45jLi and is situated usually dorsal to the cirrus and vagina, but occasionally ventral. Linstow (1889:243) gave the diameter as 56//. Near the scolex of the youngest strobila at hand it was found to be only about 34/i and traversed with transverse and sagittal muscle fibres. Within the scolex the two strands gradually converge and become united between the bothria by several weak and indistinct strands in heu of a commissure. The excretory vessels are small and irregular in number and arrangement in the mature segments. Lonnberg gave their number as 10 in young segments and from 30 to 35 in mature proglottides, but anteriorly and in young strobilas, there are two chief canals, as stated by Linstow, close within the nerve strands, accompanied by several smaller ones. They break up in the pseudo- scolex into an irregular plexus and posteriorly in the youngest strobilas empty into the terminal vesicle, sho^Ti in figure 63. The first traces of the rudiments of the reproductive organs were seen 5.2mm. from the anterior end of the smallest strobila found, which v/as 22mm. in length. The genital cloacae alternate irregularly from side to side, altho they may be situated on one side for stretches involving at least five proglottides. Dujardin (1845:617) described them as being unilateral or very irregularly alternating, while Linstow (1889:244) said they were one-sided, and between the middle and hinder one-third of the edges of the proglottides. In the sec- tions made they were found between the first and second thirds, often covered by the edge of the proglottis next ahead and from 35 to 75m in depth. Since the actual opening is usually closed by the longitudinal contraction of the strobila, it is dif&cult to distingtiish it externally from grooves separating con- secutive proglottides or other lateral grooves between irregular rugae. The vagina opens immediately behind the cirrus and slightly ventral, there being no distinct ductus hermaphroditicus. This corresponds with Lonnberg's and Linton's finds, whereas Linstow said that it is opened ahead of the cirrus. The testes are arranged in two lateral fields between the nerve strands and the uterus and ovary in the median Hne. and are strictly discontinuous, that is, separated longitudinally into sets corresponding with the other genitaUa by the transverse muscular septa between proglottides. Their average maximum length, width and depth are, respectively, 40, 90 and 85/x, thus indicating 469] PSEULGPHYLLIDEA FROM FISHES— COOPER 181 that they are usually quite flattened anteroposteriorly. Linstow gave the diameter as 0.06mm. As stated by Lomiberg, they show various stages in the development of spermatozoa quite well. Altho Linstow described them as being arranged in an elongated half-ring on each side, they were found by the writer to occupy all parts of the medulla in the fields indicated, intermingling irregularly with the vitelline foUicles, but in general more num.erous in the median frontal plane. From 23 to 30 are present in each lateral field, thus making the total number for the proglottis from about 45 to 60. The vas deferens forms an elongated mass of coils in the anterior portion of the proglot- tis, which extends from the uterus-sac to the cirrus-sac, near which its coils are fewer in number and more openly arranged. The whole mass has a length (transversely) of 0.35mm. by a diameter (longitudinally) of 0.07 to 0.08. As pointed out by Liihe (1900a) the duct forms within the cirrus-sac a proximal winding ductus ejaculatorius — it is often quite dilated — and a distal straight cirrus proper, which occupies half the length of the sac. The cirrus-sac varies in length from 174 to 277^ and in maximum diameter, medially, since the whole is ovoid with the narrow end outward, from 92 to 102/x. Liihe gave the m.ea- surements as 220 by 75 to 90ju. As noted by the same writer, myoblastic nuclei form such a thick layer outside of the wall and there are so many parenchy- matous nuclei within the sac, that the wall itself is at first difficult to locate in sections. The cirrus proper may have a dorsoventral diamiCter of 40ju. The vagina has a diameter of 20^ as it passes the cirrus-sac, and is fined with a comparatively thick cuticula. Liihe stated that the ventral bow in its course is more median than in A. crassum, but in the material sectioned the very reverse was found to be the case. The ovary of this species is very con- spicuous since it is large (0.6mm.) v/ide compact and somewhat kidney- shaped; Linstow's measurements are 0.14mm. v.ide by 0.12 long. There is no distinct isthmus, or, as Lonnberg stated, there is a very broad one, both longitudinally and dorsoventrally, from the middle of the anterior face of which the oviduct arises either towards the dorsal or the ventral surface. The ova are large and conspicuous because of their prominent nuclei which are from 10 to 13/z in diameter, while their nucleofi are about l.Sp.. Linton (1890: 752) gave these data as 8 to 14 and 2.5/i, respectively. The oocapt has a dia- meter of about 34ju. From it the oviduct proceeds laterally at first, then with a sharp turn back, i.e., ''towards the side opposite the genital-opening," it is joined by the vagina just before it makes a second turn towards the dorsal surface of the proglottis (Fig. 109). The viteline folUcles are, as stated by Lonnberg, entirely within the parenchymatous muscle-sac — and thus discontinuous longitudinally— altho Luhe (1910:26), probably basing his statements on Matz's (1892:113) description, said that they are "... zum Teil noch nach inner von der Langsmuskulatur. " They are arranged in two lateral fields corresponding to those occupied by the testes with which they intermingle freely, altho being situated more peripherally. They are somewhat irregular in shape and size, but usually compressed anterpostenorly, and as much as 90/i wide, 30 long and 70 thick. There is a median field free of them 182 ILLINOIS BIOLOGICAL MONOGRAPHS [470 both dorsally and ventrally. Right and left vitelline ducts passing to the median line close to the ventral layer of transverse muscles unite ventrally to form a common duct, which acts as a yolk reservoir. The imion of the common vitelline (Fig. 109) duct with the oviduct takes place in the median frontal plane, a little aside from the median Hne and just beyond the bend in the oviduct before which is located the point of union of the vagina. The shell-gland is quite compact and situated close to the dorsal wall of the medulla. The uterine duct takes only a very few short coils, mostly in the dorsoventral direction close to the median line, before passing into the very capacious uterus- sac. The latter vies with the large ovary in filUng up the median portion of the medulla, and measures in mature (not gravid) proglottides, 0.74mm. wide, 0.74 long and 0.37 deep, being obviously quite flattened in the antero-posterior direction as are the other organs. In mature proglottides which are quadrate in shape it may be still somewhat elliptical in outUne, as much as 1 .6mm. long by 1.3mm. wide, and show distinct lobations; whereas the widest and most gravid joints may be little else than sacs of eggs, the rest of the reproductive system in both cases having almost entirely degenerated. The uterus-sacs were con- stantly found to be rounded or lobate laterally, as stated by Matz and Liihe. The openings form a somewhat irregular zig-zag row on the ventral surface of the strobila, without, however, being accommodated in a distinct groove. The eggs, taken from gravid uteri and measured in the formalin in which the strobilas were preserved, were, externally, 80 to 98/x long by 75 to 92 wide ; mantle, 67 by 62ijl; "ectoderm " (of Schauinsland), 62 by 54jLi; and oncosphere, 52 by 40;u. The similar data given by Dujardin, which were considered by Lin- stow to be not of this species, were: shell, 80 to 110 by 50 to 57 ij.; "ectoderm, " or inner shell, 51 to 57fx; oncosphere, 48 to SOfx. Linstow's figures, copied by Liihe, were 59 by 43/i. The earliest stages in the development of this species have long been known from the work of Schauninsland (1885:527), who followed it to the escape of the oncosphere enclosed in the non-ciHated mantle. Saint Remy (1900:296-7) thought that he probably saw polar bodies and the male and female pronuclei among other important finds, and came to the conclusion "... que les phenomenes sont essentiellement les memes chez les Bothriocephales et chez les Taenia et se resument dans la constitution de deux enveloppes autour de I'embryon hexacanthe, " Olsson found a small strobila 22mm. in length in Gadus aeglifinus, which he considered to belong to this species; but apart from this there seem to be no other references in the literature to the development of the strobila from the plerocercoid. As stated above, the smallest found by the writer was also 22mm. in length, but no such invagination of the scolex as mentioned by Olsson was observed. As stated above, there is considerable e\adence in the literature of this species to indicate that the form found in marine Gadidae and called A. gadi by van Beneden (1871:56) is not the same as that found in the only fresh- water gadid, viz., Lota. In endeavoring to place a number of specimens from Lota maculosa, it was found that in many points they agreed with the descrip- 471] PSEU DOPEY LLIDEA FROM FISHES— COOPER 183 tion given by Matz for A. rugosum. The scolices are more or less alike, no pseudoscolex (see below, however) being present; the longitudinal muscles are not in bundles; the genital cloacae are irregularly alternating from side to side; the vagina opens ahead of the cirrus instead of behind; the testes are continuous from proglottis to proglottis; the vitelline foUicles are located among the longitudinal muscles and are discontinuous; and the uterus-sacs are rounded laterally. In most of these and in many more points, on the other hand, the form agrees with A. crassum, so that the writer is obUged to consider it to belong to that species. Furthermore, a direct comparison of Matz's description with that of Lonnberg brings out many differences. Lonnberg described a pseudoscolex, calcareous bodies, the longitudinal muscles in bimdles, the other sets of parenchymatous muscles as above described, the vagina opening behind the cirrus and ventrally, testes discontinuous, vitelline follicles within the parenchymatous muscle-sac and also discontinuous, none of which char- acters are to be found in Matz's description, but all of which apply to the material at hand from marine Gadidae. It is to be noted here that Lonnberg accepted the specific name rugosum of Rudolphi instead of the gadi of van Bene- den, which as will be seen presently may not be admissable. Going back, then, to the only other and the earhest description of the anatomy of the spe- cies, namely, that of Linstow (1889:242-5), similar difficulties and confusion are met with, Linstow gave as hosts for the species, which he called B. rugosus Rud., Gadus aeglifinus, G. morrua, Merlangus carbonarius, M. pollachius, Mer- lucius vulgaris, Lota vulgaris, L. molva and Motella mustela. Characters in his description not appUcable to the material studied are: No pseudoscolex, but scolex of a rather peculiar shape and structure terminally; nerve strand 56/x in diameter; 10 excretory vessels anteriorly arranged in two groups of five each; genital cloacae unilateral, between the middle and hinder thirds of the edge of the proglottis; vagina opening ahead of the cirrus; length of cirrus-sac 0.42mm. (!) ; ovary 0.14 by 0.12mm. ; uterus spherical when obviously young; and eggs 59 to 43^. Testes with a diameter of 60/x, vagina 16 to 26/x in diameter at the beginning, and two vitelline ducts, besides a few other minor points in the general anatomy, agree, however, with the species as studied by the writer. Thus it is seen there is by no means anything Uke complete agree- ment as regards details among the three descriptions by Linstow, Lonnberg and Matz. But this does not seem to have inconvenienced many of the writers since then, notably Ariola (1900:432) and even Liihe (1900a) whose references to the position of the vitelline folUcles and the ventral bow in the vagina are at variance with conditions described here; altho Johnstone (1907), Scott (1909) and NicoU (1910) were obviously dealing with the form described by Lonnberg, Schneider (1903a :7-10) seems to have been the only one who pointed out the differences between the form from Lota and that from marine Gadidae. He said: " Bothriotaenia rugosa gleicht sowohl in ihrem Aussehen, als auch in ihrer Anheftungsweise ausserordenthch der Species B. proboscidea, die in unseren Lachsen {Salmo salar) so massenhaft vorkommt. Trotzdem pflegt man aber seit Rudolphi, soviel mir bekannt, immer die in Lota meist vorkem- 184 ILLINOIS BIOLOGICAL MONOGRAPHS [472 mende Form als eine getrennte Species auf zufassen unter derti Namem ' rugo- sa' {Bothriocephaliis rugosus Rud. = Dibothrium rugosum Diesing, u.s.w.), ob- gleich die unterscheidenden Merkmale zwischen B. proboscidea und B. rugosa, die Riggenbach in seinen 'Bemerkungen ueber das Genus Bothriotaenia Railliet' iibersichtlich zusammenstellt, recht unbedeutend sind und vielleicht doch noch in Rahmen der Variationsbreite einer einzigen Species untergebracht wer- den konnen;" and, as regards the latter, in a footnote: "Die von M. Liihe ... als Unterscheidungsmerkmal vorgeschlagene Lage der Dotterstocke zum Theil {B. rugosa), bzw. auschliesslich {B. proboscidea) zwischen den Langs- muskeln, scheint mir auch nicht genugend constant sein, um als Speciesmerk- mal verwandt werden zu konnen. " For material from Lota vulgaris Schneider described a scolex and segments both similar, as he pointed out, to those of B. proboscidea { = A. crassum). The arrangement of the genital cloacae, irregularly alternating but unilateral for long stretches, the openings of the uteri in a longitudinal furrow, the early form of the uterus-sac and the size of the eggs (64.5 by 50 to 52/i), as described by the same worker, all agree with A. crassum as studied by the writer. In conclusion Schneider said: "Uebri- gens habe ich, wie gesagt, auch an die Examplaren aus dem Museum keine Pseudoscolexbildimg bemerkt und zweifle daran, dass B. rugosa und B. gadi ein und dieselbe Art sind," and further, "Es ist mir iibrigens bisher noch nicht gelungen, B. rugosa oder B. gadi in Gadus morrhua des Finnischen Meerbusens aufzufinden, obgleich ich zahlreiche Exemplare des Dorsches seciert habe, und obgleich B. rugosa in Lota vulgaris hier oft genug vorkommt. Auch das scheint gegen die Identitat der Species B. rugosa mit B. gadi zu sprechen. " Thus it is seen that there is considerable detailed evidence that the species from Lota is not the same as that from the marine hosts. One must then go back of Linstow's time in order to determine, if possible, what is the correct name for the latter. Next in retrogressive order is van Beneden's (1871 :56) description of A. gadi, confined to a short footnote which deals with Kttle more than the pseudoscolex. So far as it goes this agrees with Loimberg's A. rugosum and with the material studied by the wTiter. Olsson (1867 :54) was obviously dealing with the same form which he reported from marine hosts only. Diesing (1863 and 1850) copied from Rudolphi, while Cobbold (1858) had the marine form before him, and Baird (1853) had the fresh-water form. In spite of Linstow's objection the writer feels certain that Dujardin (1845) also had the species dealt with here, especially since his measurements of the eggs come nearest to those observed than do those of any other writer. It remains then to enquire into Rudolphi's finding and description, as Leuckart (1819:57) copied from him altho at the same time remarking that "Ist am nachsten mit den B. proboscideus verwandt, imd, wenn er nicht eine Art mit diesem ausmacht zwischen B. proboscideus und B. sagittatus zustellen. " For B. rugosus Rudol- phi (1810:42) described a scolex, comparable to that of his B. proboscideus and to Linstow's description and figure of the organ, no neck, and segments "primi angusti, fere quadrati, insequentes latitudinis ratione habita brevissimi, saepeque inequales, vel hinc inde angustiores; margines obtusi crassiusculi. " 473] PSEUDOPHYLLIDEA FROM FISHES— COOPER 185 This, with "neque ovaria, neque foramina articulorum vidi ..." and the further fact that he obtained his specimens from Gadus lota { = Lola vulgaris), leads the vsriter to beUeve that he was not dealing with the form present in marine hosts but with a form which, if not identical with A. crassum ( = his B, infundihuliformis and B. proboscideus) , was very close to it. One must then go back farther to Batsch (1786:208) where the species T. riigosa was named on the basis of Goeze's (1782:410) description of "Der runzlichter Fischband- wurm" from Gadus mustela ( = Motella mustela), the marine five-breared rockhng of Europe, which the latter called T. tetragonoceps Pallas, with some doubts, however, as discussed under the next species dealt with here. Batsch gave the following diagnosis of T. rugosa: "Taenia (larvata) capite conico cum corpore subconfluente, papillis laterali- ter adnatis usque ad apicem capitis, eisque binis: articuUs brevissimis, dila- tatis, corpore serrato." He used Goeze's figures 1 to 4 and pointed out that he (Goeze) recognized differences between his specimens and Pallas' T. tetragonoceps, for "Er rechnet beyde Wlirmer fur eine Art, und die Glieder nebst dem ganzen Korper haben viel Gleichheit, auch die aussere Gestalt des Kopfs. Doch sind bey diesem letztem die Saugblasen bey weiten nicht so deutUch gezeichnet, und steUen vielmehr, wie sich Gotze ausdriickt, zwey Backenbarte vor. Die Furche auf dem Korper ist auch vorhanden, nur scheint der Korper m.ehr gestreckt, und am Rande mehr zackig zu se^Ti. " Consequently the correct name of the species depends on whether Goeze's description, augmented by Batsch's con- tributions, is considered to be applicable to the material at hand. The largest of Goeze's specimens measured in warm water a yard and half in length by scarcely one-half a hne in breadth; but the latter is decidedly at variance with his figures 1 and 2 which he said were drawn in "natiirlicher Grosse," in which case the width would be from 7 to 15 hnes and the scolex about 17.5 lines in length! For these large specimens — even tho only the first set of measure- ments were taken into consideration — he described and figured nothing of diagnostic value other than a scolex provided with two bothria pretty much of the ordinary type, behind this a "distinctly jointed" and "almost cylindrical" neck and along both surfaces of the posterior closely crowded segments a median longitudinal furrow, all of wliich characters more nearly agree with the proboscideus type of A. crassum rather than with the A. rugosum described here. And since the latter is clearly not T. tetragonoceps Pallas as described by Batsch (1786:204), the only course that seems open is to refer the species to van Ben den's A bothrium gadi. However, in view of the fact that no material from the European ling {Lota vulgaris) was available for a comparative study, the writer does not feel justified in taking this step, but here retains at least tentatively the specific name Abothrium rugosum (Batsch 1786), nee A. rugosum Goeze 1782. The material studied consisted of lots 295, 296, 297, 298, 299, 300, and 302 from Mdanogrammus aeglifinus (L.), the haddock, and 301 from Gadus cal- larias, the cod in the writer's collection; and 17.53 in the collection of the University of Illinois, also from the cod. 186 ILLINOIS BIOLOGICAL MONOGRAPHS [474 ABOTHRIUM CRASSUM (Bloch 1779) [Figs. 37-42, 50-54, 64, 77, 92] 1779 Taenia crassa Bloch 1779 : :545 1780 Taenia sdlmonis Miiller 1780 : : 179, 202 1781 Taenia tetragonoceps (part.) Pallas 1781 : :87 1782 Taenia capite truncato Bloch 1782 ; :410 1782 "Der runzlichter Fischbandwurm " Goeze 1782 : :410 1782 Taenia proboscis suilla Goeze 1782 : :417 1786 Taenia tetragonoceps Batsch 1786 : :204 1786 Taenia proboscidea Batsch 1786 ; :212 1790 Taenia salmonis Gmehn 1790 :3080 1790 Taenia salvelini Schrank 1790 ; :125 1793 Taenia salvelini Schrank 1793 : :141 1795 Taenia salmonis Rudolph! 1795 : ;17 1802 Taenia salmonis Bosc 1802 ; :308 1802 Taenia proboscidea RudolphI 1802 : :106 1803 Rhytis salvelini Zeder 1803 :292 1810 Bothriccephalus proboscideus Rudolphi 1810 :39 1810 Bothriocephalus infundibuliformis Rudolphi 1810 ; :46 1816 Bothriccephalus proboscideus Lamarck 1816 :582 1819 Bothriocephalus proboscideus Rudolphi 1819 : 137, 472 1819 Bothriocephalus infundibuliformis Rudolphi 1819 : 137, 473 1819 Bothriocephalus proboscideus Leuckart 1819 :38 1819 Bothriocephalus infundibuliformis Leuckart 1819 :42 1843 Bothriocephalus salmonis umblae Koelliker 1843 :91 1844 BothriocephMlus proboscideus Bellingham 1844 -.252 1844 Bothriocephalus infundibuliformis BelHngham 1844 :253 1845 Bothriocephalus proboscideus Dujardin 1845 :615 1845 Bothriocephalus infundibuliformis Dujardin 1845 -.616 1846 "Bothriocephalus du Saumon" Blanchard 1847 :116 1850 Dibothrium probcscidetim Diesing 1850 :590 1850 Dibothrium infui:dihulifcrme Diesing 1850 :590 1853 Bothriocephalus proboscideus Baird 1853 :88 1853 Bothriccephalus infundibuliformis Baird 1853 :88 1S63 Dibothrium proboscideum Diesing 1863 :242 1863 Dibothrium infundibidiforme Diesing 1863 :242 1867 Bothriocephalus proboscideus Olsson 1867 :53 1871 Bothriocephalus proboscidea van Beneden 1871 :69 1878 Bothriocephalus infundibuliformis Linstow 1878 :263 1884 Bothriocephalus infundibuliformis Zschokke 1884 :21 1889 Bothriocephalus suecicus Lonnberg 1889 :35 1892 Bothriocepltalus infundibuliformis Matz 1892 :110 1893 Bothriocephalus infundihdiformis Olsson 1893 :17 1893 Bothriocephalus proboscideus Olsson 1893 :17 1894 Bothriotaen ia infundibuliformis Blanchard 1894 :701 1896 Bothriotaenia infundibuliformis Ariola 1896 :280 1896 Bothriotaenic infundibuliformis Riggenbach 1896 :223 1859 Abolhrium crassum Luhe 1899 :39 1900 Bothriotaenia proboscidea Ariola 1900 :433 1900 Abothrium crassum Liihe 1900a -.97 1909 Bothriocephalus proboscideus Scott 1909 :78 1910 Abothrium crassum Liihe 1910 :26 1910 Abothrium crassum Ward 1910 :1184 475] PSEUDOPHYLLIDEA FROM FISHES— COOPER 187 Specific diagnosis: With the characters of the genus. Large cestodes with maximum length, breadth and thickness of 870, 6 and 2mm., respectively. Scolex variously shaped; usually rounded posteriorly and truncated anteriorly; with prominent bothria and terminal disc. First segment may or may not be elongated to form a short neck. Proglottides at first broad and short or more quadrate, cuneate or infundibuliform in shape; in the middle of the strobila, five or more times broader than long; posteriorly, quadrate or as long as broad. Usually a median longitudinal groove down each surface of the strobila formed by emarginations on the posterior borders of the segments. Cuticula 4 to 6/x thick, subcuticula 40 to lOO^t. Calcareous bodies (?) absent in adult strobilas. Longitudinal muscles not in bundles; no muscular septa between proglottides. Nerve strands 25 to 40^ in diameter, dorsal to inner end of cirrus-sac. 12 chief excretory vessels, 6 on each surface just within the transverse muscles, reduced to 6 or 8 anteriorly. Genital cloaca irregularly alternating, but unilateral for long stretches; from one-third to one-half way along the margin of the proglottis. Vagina opens ahead of and sUghtly ventral to the cirrus; no distinct hermaphroditic duct. Testes within the nerve strands, pseudostratified, continuous from joint to joint; elongated dorsoventrally, 95 to 115 by 70 to lOO/x; 40 to 150 in num- ber. Vas deferens lateral, elongated, with few coils before entering the cirrus- sac, 350 to 600 by 100 to ISO^i in dimensions. Cirrus-sac ovoid with narrow end outward, 130 to 380 by 60 to 150/x. Cirrus proper an almost straight tube in outer half of sac. Ovary comparatively small, irregular or somewhat lobed, with thick isth- mus, 0.8mm. wide by 0.13 long. Oocapt 40/z in diameter. Usually two ven- tral vitelUne ducts unite to form a common duct which does not act as a reser- voir. Vitelline folUcles irregular in shape and size, among the longitudinal muscles or outside of them, discontinuous. Shell-gland small, compact, dorsal. Uterine duct with only a few coils near the median line. Uterus-sac trans- versely elliptical or somewhat quadrate and shghtly lobed, rounded laterally filling up almost the entire proglottis when gravid; opening in the median line opposite emarginations of segments ahead. Eggs, 45 to 115 by 30 to 75/lc; ovoid or ellipsoid in shape. Habitat: In the pyloric coeca and intestine of the host. HOST LOCALITY COLLECTOR AUTHORITY Salmo salar Borke Rudolphi BeUingham Dujardin M. C. V. Siebold & Johns- ton (CoU. Brit. Mus.) Goeze 1782 : 417 Salmo salar Salmo salar Salmo solar Salfno Millar Gryphswald Ireland Paris Rudolphi 1819 : 137 Bellingham 1844 : 253 Dujardin 1845 : 615 Diesing 1850 : 590 Salmo salar Baird 1853 : 88 188 ILLINOIS BIOLOGICAL MONOGRAPHS [476 HOST LOCALITY COLLECTOR AUTHORITY Sdmo solar Warberg Olsson Olsson 1867 : 53 Salmo solar Belgian coast van Beneden van Beneden 1871 :69 Salmo solar Wamemiinde Zschokke Braun 1891 : 55 Salmo salar Naset Olsson Olsson 1893 : 17 Salmo solar Phine R., Basel Zschokke Zschokke 1896 : 776 Salmo salar nobilis Murman-Kuste Zool. Mus., Kais. Akad. Wiss., Petrograd Linstow 1903 : 20 Salmo salar sebago Lake Sebago, Me. Ward Ward 1910 : 1184 Salmo alpinus Salmo alpinus Mus. Vienn. Rudolphi Olsson 1819 : 137 Jenitland Olsson 1876 : 149 Salmo alpinus Lakes Nackten, Storsjon, Lock- nesjon Olsson Olsson 1893 : 17 Salmo carpio L. Garda, Italy Ninni Stossich 1890 : 7 Salmo caspius Karabugas-Strasse Maximovic Linstow 1903 : 20 Salmo fario Ireland Bellingham Bellingham 1844 : 252 Salmo fario Rome Condorelli Ariola 1900 : 435 Salmo fario Vyg-Fluss Danilevskij Linstow 1903 : 20 Salmo hucho Mus. Vienn. Rudolphi 1819 : 472 and Bremser Salmo lacustris Benaco Largaiolli Ariola 1900 : 435 Salmo namaycush Shoal Id., Lake Superior Milner Ariola 1900 : 435 Salmo salvelinus Schrank Stiles & Hassall 1912 : 402 Salmo salvelinus Zeder Stiles & Hassall 1912 : 403 Salmo salvelinus Mus. Vienn. Rudolphi 1819 : 137 Salmo salvelinus Diesmg Milner Diesing Ariola 1850 : 591 Salmo siscowet Outer Id., Lake 1900 : 435 Superior ? Salmo thym^llus Salmo thymallus vexillifer Salmo trutta Coll. Vienn. Leuckart 1819 : 43 M. C. V. Diesing Bellingharr 1850 : 591 Ireland Bellingham I 1844 : 253 Salmo trutta Coll. Brit. Mus. Olsson Baird Olsson 1853 : 88 Salmo trutta Lakes Storsjon, 1893 : 17 Halen, Refimds- sjon, Sallsjon, & Ockesjon, Jemt- land Sdmo trutta Miu^nan-Kiiste Zool. Mus. d. Kais. Akad. Wiss., Petrograd Linstow 1910 : 281 Salmo umbla M. C. V. Diesing Zschokke Zschokke 1850 : 591 Salmo umbla Zschokke Zschokke 1884 : 21 Coregonus fera 1884 : 21 Coregonus lavaretus Lakes Storsjon and Nalden Olsson Olsson 1893 : 17 477] PSEUDOPHYLLIDEA FROM FISHES— COOPER 189 HOST LOCALITY COLLECTOR AUTHORITY Coregonus oxyrhynchus Warberg Olsson Olsson 1867 : 53 maraena Trutta fario Genfersee, Basel Zschokke Zschokke 1896 : 776 Truita lacustris Rhine R., Basel Zschokke Zschokke 1896 : 776 Trutta lacustris Bodensee Hofer Hofer 1904 : 221 Trutta salar East Prussia Muebling Muehhng 1898 : 35 Truita trutta Wamemiinde Zschokke Braun 1891 : 55 Trutta variabilis Zschokke Zschokke 1884 • 21 Thymallus vulgaris Thymallus vulgaris Zschokke Zschokke 1884 • 91 Storsjon, Jemtland Olsson Olsson 1893 : 17 Thymallus vulgaris Baikal-See Zool. Mus. d. Kais. Akad. Wiss., Petrograd Linstow 1903 : 20 Esox lucius Zschokke Zschokke Olsson Zschokke 1884 : 21 Perca fluviatilis Osmerus operlanus Zschokke 1884 : 21 Bonan, Gestricia, Olsson 1893 : 17 Gulf of Bothnia Clupea harengus Ostsee Schneider Schneider 1902 : 28 Lota vulgaris Storsjon, Jemt- land Olsson Olsson 1893 : 17 Lota vulgaris Dvina-Fluss Danilevskij Lmstow 1903 : 20 "Trout" Loch Tay WilHamson Scott 1909 : 78 Salmo salar St. Andrews, N.B., Cooper Cooper Bay of Fundy (the present paper) Cristivomer namaycush Giants Tomb Id., Cooper Cooper Georgian Bay, (the present paper) L. Huron Cristivomer namaycush Port Credit, Ont., Cooper Cooper Lake Ontario (the present paper) Cristivomer namaycush L. Temagami, H. B. Ward Cooper Ont. (the present paper) Cristivomer namaycush Charlevoix, Mich. H. B. Ward Cooper (the present paper) Cristivomer namaycush Pentwater, Mich. H. B. Ward Cooper (the present paper) "Lota lota" Charlevoix H. B. Ward Cooper (the present paper) Lota maculosa Port Credit Cooper Cooper (the present paper) Lota maculosa Potaganissing, G. R. LaRue Cooper and Sitgreaves (the present paper) Bays, L. Huron Lota maculosa Charlevoix, Mich. Cooper Cooper (the present paper) Coregonus clupeiformis Giant's Tomb Cooper Cooper Island (the present paper) Coregonus clupeiformis Potaganissing G. R. LaRue Cooper Bay, L. Huron (the present paper) Salvelinus fontinalis Harrietta, Mich. G. R. LaRue Cooper (the present paper) 190 ILLINOIS BIOLOGICAL MONOGRAPHS [478 This species, originally given the specific name of Taenia crassa by Bloch (1779:545), was on the one hand confused with A. rugosum and on the other hand given the new name Taenia proboscis suilla by Goeze (1782:410 and 417, resp.) according as it was found in Gadus or in Salmo salar. This confusion was evidently due to the fact that the latter followed Pallas (1781) in caUing it T. tetragonoceps; for, as he said, "Pallas setzt ihn mit Recht I.e. unter die neuen Arten. [In the footnote, he considered that T. tetragonoceps PaUas, Taenia crassa Bloch and T. capite truncato Bloch were all synonymous]. Er hat ihn in verschiedenen Fischen, im Rhein- and Elb-lachs, auch in kleinem Lachs (Eriox) am grossten im Babeljau, im Dorsch, in Schollen und Aalen ; der Graf von Borke in der Teufelsmoraene und Meergrappe; D. Bloch in der Madui- Moraene und im Rheinlachs gefunden." But in spite of this, he expressed doubt on the synonym of the forms from the Gadidae and from the Salmonidae in the next paragraph: "Da aber die Zeichnungen des Pallas von der Abbildung des D. Blochs von diesem Wurm, so sehr verschieden sind; und die letztere die namliche ist, die mir der Graf von Borke von dem Fischwurm aus dem Aal zuge- schickt hat; so vermuthe ich fast, dass es dennoch verschiedene Arten sind;" and immediately supported this contention by comparing Loewenhoek's "Vermes multimembres ex Anguilla" (vide supra = 5. claviceps) with Pallas form and pointing out differences. Elsewhere (p. 417) he described under the name "Der Schweinriissel Taenia Proboscis Suilla: articulis foliaceo sinuosis. " from Salmo salaris L. what was without doubt the B. proboscidea of later writers. Goeze's diagnosis of this form is as follows: "Vom Graf von Borke aus einem siebenpfundigem Lachs {Salmo salaris L.). Besonders in den Blinddarmen. Der Kopf wie ein Schweinsriissel, mit vier langlichten flachen Saugblasen. Gleich hinter dem Kopfe, ohne Hals, die Blatterformigen ausgeschweiften GUeder. Ich will nicht mit Gewissheit be- haupten, dass dies eine ganz besondere Art sey. So hatte ihn der Graf von Borke gesehen und der Kopf unterscheidet sich von andern. Diese Zeichnung, die ich hier liefre, war auch dem Hr. D. Bloch, mitgetheilet. " The explanation (p. 418) of the figures 1 and 2, Table XXXIV, here referred to, indicate, incidentally, that he considered the bothria to be lateral instead of dorsoventral in position. Rudolphi (1810:39, 46, resp.) gave the first diag- noses of the two species, viz., B. proboscideus and B. infundibuliformis, which were later united by Zschokke (1884:21) and Matz (1892:110) into one species, now known as A. crassum. Rudolphi's later (1819:137) condensed diagnoses are here given for the sake of comparison : "2. Bothriocephalus proboscideus R. B. capite bothriisque marginalibus oblongis, collo nullo, corpore depress© medio sulcato, articuUs brevissimis, antrorsum attenuatis. " "5. Bothriocephalus infundibuliformis R. B. capite bothriisque oblongis, coUo nullo, articulis variis, primis rugaeformi- bus, sequentibus subinfundibuliformibus, reliquis brevioribus. " In the same work (pp. 472, 473) he pointed out resemblances between these two species in that, as regards B. proboscideus, "Specimina maxima in intestinis Salmonis 479] PSEUDOPHYLLIDEA FROM FISHES— COOPER 191 Huchonis reperta, quae Bremserus mecum communicavit ad speciem insequen- tem (praesertim parte anteriore) transitum faciunt;" and under B. infundibuli- formis, the following species, concerning the same specimens: "... quae parte anteriore cum B. proboscideum arguunt." Leuckart (1819:38, 42) ac- cepted Rudolphi's two species and gave good figures of the scolices and anterior ends of the same; but recognized two forms of B. proboscideus, viz., "a. Collo nullo; corpore medio sulcato. Habitat in Sahnonis salaris appendicibus pyloricis. b. Collo brevissimo; corpore medio non sulcato. Habitat in Sahnonis Huchonis intestinis." He further pointed out and corrected the errors of Pallas, Bloch and Goeze regarding the scolex, and concerning B. infundibuliformis said : "Komme B. proboscideus am nachsten, ist aber gewiss eine von ihm verschiedene Art, obgleich Bremser . . . sagt, dass er beide Arten nicht gem trennen mogte." Bellingham (1844:252) was evidently the first to comment on the relation be- tween the number of individuals of this species and the condition of the host, when he said, "I have found the B. proboscideus in such numbers in the in- testines and pyloric appendages of the Salmo salar as almost completely to block up these parts, which contained nothing besides but a white tenacious mucus. The fish in which they were most numerous were amongst the finest in the market; which would help to prove, that in these animals at least, the presence of entozoa in the alimentary canal is not to be regarded as the result of disease." He pointed out the great variation due to different states of contraction or relaxation of the scolex and segments and also that B. infundi- buliformis from Salmo trutta "... resembles generally the B. proboscideus, but differs from it in some respects. " While Olsson (1867 :53) and Van Beneden (1871:69) found only B. proboscideus, others recognized Rudolphi's two spe- cies; so that it remained for Zschokke (1884:21-25) to compare the two species in detail and point out that they must be considered only different forms of the same species. Later investigations into the anatomy by Matz (1892:110), who, however, studied only the proboscideus form from Trutta trutta and Salmo salar, were considered to have established this contention, altho Olsson (1893 : 17) still reported both of the older species with some doubt as to the use of the name B. infundibuliformis. Blanchard (1894:701), Ariola (1896:280), and Riggenbach (1896:223) evidently accepted only the comhmdiWou Abothrium crassum (Bloch) which is now generally accepted. Ariola (1900:433), however, called the species Bothriotaenia proboscidea (Batsch), thus disregarding the fact that Batsch (1786:212) renamed Bloch's T. crassa. In general appearance the material studied agreed with the descriptions of both B. proboscideus and B. infundibuliformis of the early writers; for the for- mer type from Salmo salar, the Atlantic sahnon, would at first sight be consid- ered to belong to a different species from those taken from the fresh- water hosts. The largest of the latter was one from a specimen of Cristivomer namaycush, which measured 856mm. in length by a maximum breadth of 3mm., while the largest from the salmon measured 754mm. in length, 6mm. in maximum 192 ILLINOIS BIOLOGICAL MONOGRAPHS [480 breadth and about 2mm. in thickness. One from Coregonus clupeiformis measured 292 by 1.8mm. and another 185 by 2mm., while those from Lota maculosa were all small, fragmentary and mostly immature. The dimensions are according to Liihe (1910:27) about 300mm. in length by about 1.5 to 3.5 in breadth; to Zschokke (1884:23) 350 by 4mm.; and to Ariola (1900:435) 250 to 400 by 2 to 4mm. Thus it is seen that as regards size the two forms are more nearly alike in Europe than here. Consequently one is not surprised to read in the comparison by Zschokke, "En effet je trouvais souvent dans le meme poisson, meme dans le meme appendice pylorique des exemplaires dont les uns se rapprochaient evidemment du Bothriocephalus proboscideus, tandis que les autres presentaient les caracteres de Vinfundihuliformis. Souvent aussi les caracteres des deux especes etaient reunis sur im seul individu, par exemple le cou assez prononce avec des proglottis en forme de batons, ou point de cou avec les proglottis infundibuliformes bien caracterises. " In preserved material the scolex assumes a great variety of shapes, from the much elongated form with the "neck" of Olsson (1893:17) and earher writers shown in figure 37, to that from Salmo salar, shown in figure 39. Altho the latter is much the largest and apparently quite different from the former, scolices quite Uke it excepting for size were seen in specimens from the lake trout, and all stages between these two extremes were observed. The form with the neck, it may be said, is much more common in the youngest strobilas and plerocercoids (Figs. 53, 54). Regarding this structure Zschokke (1884:24) said that, "a I'etat de forte contraction le cou disparait presque completement. " Those from Lota maculosa, the ling, need special mention since, as shown in figure 38, the terminal disc and anterior half of the organ of fixation is in many instances greatly swollen to form a sort of pseudoscolex which is usually found imbedded in the walls of the pyloric ceca of the host or often simply protruding into the lumina of the ceca. But this modification was found only in the older strobilas; in the younger chains the scolex is as shown in figures 41, 42, which are drawn to the same scale. The largest with this first form of scolex was 30mm. in length by 1.2 in breadth, while the shortest with the swollen end was 20 by 1.0mm. ; so that somewhere between the lengths of 20 and 30mm. the imbedding of the scolex with the concomitant enlarge- ment of the terminal disc takes place. Several intermediate stages were seen, and the swollen scohces were varied in shape and degree of intactness. The latter might seem to point to the condition being due to mechanical or physical means, but this is offset by the fact that the material was in good histological condition when sectioned. The segments also vary considerably in shape, the first ones being in speci- mens from fresh-water hosts distinctly cuneate or infundibuliform and sUghtly broader than long, the middle ones relatively broader and shorter, and the posterior segments especially in the older chains very short and crowded. Furthermore, in larger and older strobilas of the fresh-water form the posterior kind of segment, that is, the very short broad form, is found relatively farther forward, and the hinder end of the same quite similar, excepting for size, to 481] PSEU DOPEY LLIDEA FROM FISHES— COOPER 193 the worms from the sahnon. In the latter the segments, as shown in figure 39, are at first short and broadly cuneate and at once become still shorter and more crowded. On the whole the marine form of the species appears to be constantly in a better state of nutrition than the fresh-water form. As the measurements given here indicate, the strobila is much wider and thicker and the scolex much larger; but what attracts one's attention at first sight is the clear-cut nature of the scolex and segments of this, the proboscideus type, which led Bellingham (1844:252) to describe it as "a very beautiful species," as compared to the other form. In the latter the posterior, much-crowded pro- glottides, especially, are often irregularly swollen transversely or longitudinally jiO as to present appearances in many cases quite like those to be seen in A. rugosum. Much of this may, however, be due to osmotic action when the worms are near the point of death with the possible low resistance of the body- wall of the posterior segments when growth and development have gone on to such a stage that they are Uttle more than sacs filled with eggs. As pointed out by various writers the posterior borders of the segments are provided in the median line and on both surfaces with a distinct notch or emargination, which together form a longitudinal groove on each face of the chain. This is quite pronounced in the strobilas from the salmon but often not so marked in those from the whitefish, lake trout and ling. In these it is confined more to the posterior stretches of the segments and greatly exaggerated by the above mentioned irregular sweUings which, however, do not cross the longi- tudinal groove formed by these notches. Often this groove may be present in the segments close to the scolex and again in posterior ones but absent in the middle stretches, where, of course, the emarginations are either ahnost 'ibsent or all but obhterated by the degree of relaxation. On the contrary, Olsson (1893:17) often found the groove only in the middle portions of the infundibuliformis form. Many specimens also show the condition described by Leuckart (1819:42) when he said, "Die hinteren Rander dieser GUeder scheinen allerdings etwas verdickt und stehen an den Korperrandern sehr hervor. " In the anterior segments of considerably relaxed or especially young strobilas something of the manner of segmentation can be seen. This was found to take place much as in the genus Bothriocephalus, altho the writer was not able to distinguish the primary segments to his satisfaction. What was considered to be such is shown in figure 64, a sketch of segments beginning 27mm. from the anterior end of the strobila in question. The idea of domi- nance of the anterior portions over the posterior portions in segmentation, as brought out under B. scorpii, is here shown very nicely. In the proboscideus type of strobila the same method of subdivision was followed in the anterior segments, altho with greater diflaculty on account of the fact that the segments are so closely crowded in the longitudinal direction. Olsson (1867:53) noticed the subdivision of the segments producing an alternation of larger segments with smaller ones, and he considered it to be an articulatio spuria similar to that described by Wagener (1854:69) for Amphicotyle heteropleura and by Krabbe (1865:384) for B. scorpii and other species. Later Olsson (1893:17) 194 ILLINOIS BIOLOGICAL MONOGRAPHS [482 states that transverse divisions occured in B. infundibuliformis as well as in B. proboscideus. Finally, as regards the external features, it should be noted that the posteriormost, yet ripe proglottides of the smaller strobilas from the fresh-water hosts are quadrate in shape, often as long as broad, and usually somewhat narrower than the mature segments ahead. These, as stated by Olsson (1893:17), show practically nothing more in the way of reproductive organs than the lobed uterus-sacs. The following measurements of the scolex are given for the sake of comparison: HOST Salmo solar Cristivomet namaycush Lota maculosa Length 1.01mm. 0.70mm. 0.87mm. 0.71mm. Width of terminal disc 0.74 0.42 0.47 0.41 Width of bothrium (middle) 0.94 0.52 0.38 0.60 Length (laterally) 0.88 0.70 0.74 0.64 Depth of terminal disc 0.56 0.33 0.44 0.36 Depth posteriorly 1.25 0.40 0.55 0.68 The anatomy of the species was studied by Matz (1892:110), later writers referring to his work, altho Zschokke (1884:24), Lonnberg (1889:35) and Olsson (1893:17) made some valuable contributions, while Liihe (1899a and 1900a) dealt with it from a comparative standpoint. Most of them, however, con- fined their attention almost entirely to the reproductive organs. The cuticula, from 4 to 5/.t in thickness, is divisible into two layers besides the basement membrane, an outer and darker occupying about one-third of the thickness of the whole, and quite smooth, and an inner, quite light layer. It is slightly modified on the posterior borders of the segments to form minute spinelets which are evidently formed by the sphtting of the somewhat thickened outer layer. This modification is, however, not so well marked as in other species. The subcuticula, from 60 to 100/i in thickness, extends from the cuticula to the longitudinal muscles, thus occupying the outer one-half of the cortex. Its nuclei are confined to its inner half, thus leaving the outer ends of the cells free. The whole tissue requires good fixation and preservation to show these features which in the older proglottides and longer strobilas are otherwise affected by the general degeneration coincident with the development of the enormous nimiber of eggs produced by this species. And it should be stated here that this is more apphcable to the large marine form than to those from fresh-water hosts. So far as the writer is aware no calcareous bodies have been described for this species. They were found only in the smallest strobilas with a maximum diameter of 15ju. The parenchyma is in the form of a very fine reticulum, the spaces of which form the bulk of the tissue. Unlike A. rugosum the longitudinal muscles of the parenchyma are not arranged in fasicles; nor do the transverse fibres form a septum between even the anterior segments. The latter are often more numerous towards the pos- terior end of the segments, as are the sagittal fibres, but they do not prevent 483] PSEUDOPHYLLIDEA FROM FISHES— COOPER 195 the testes from being continuous from proglottis to proglottis, nor the anterior end of the uterus-sac from protruding considerably into the proglottis imme- diately ahead; In the material from Loia maculosa the myoblastic nuclei and protoplasm of the sagittal fibres are almost as prominent as in A .rugosum. There is a weakly-developed series of external longitudinal muscles arranged in relation to the posterior borders of the anterior segments as described above. The musculature of the ordinary form of the scolex is typical. Trans- verse or circular, sagittal or radial, and longitudinal muscles are about equally developed, the latter entering the base of the organ in scattered groups, altho not distinctly fascicled, and extending to the tip. A series of well developed longitudinally arcuate fibres, arranged around the border of the terminal disc is present, quite as described by the writer elsewhere (1914a :92) for Haploboth- rium glohuliforme. In the enlarged scolex from L. maculosa, altho the general arrangement of the musculature is retained, the number of fibres is greatly diminished and the whole ensemble indicative of not a little degeneration. This is emphasized by the fact that in the unenlarged portion of the organ there is to be seen in sections a deposition of material which stains much Uke that described above for the young pseudoscoHces of A. rugosum. This is absent, however, from the enlarged terminal portion. In the form from the salmon the chief nerve strands reach a maximum dorsoventral diameter of about 100/x by a transverse diameter of 40/i. They are located at the extreme lateral limits of the medulla, all of the testes coming between them, as pointed out by Liihe (1900a), and pass dorsal to the inner end of the cirrus-sac and consequently to the vagina, as mentioned by Matz (1892:112). In the scolex the chief strands enlarge at the level of the border of the terminal disc to form two ganglia which are united by a small transverse commissure, the whole arrangement being quite comparable to that present in B. cuspidatus. Zschokke (1884:25) said that "Les canaux excreteurs sont paralleles et voisin des bords lateraux," while Fraipont (1881:12) described the system as follows: "La vesicule terminale est petite. Le systeme des canaux descen- dants est fort compUque; ils fournissent des branches laterales de volume tres variable; les unes volumineuses, les autres excessivement greles. Les branches forment un reseau a mailles tres inegales. Des canaux tres fins peuvent partir directement des gros troncs. Dans la tete, les canaux descendants forment un reticulum tres complique. Cretaines ramifications tres fines se terminent par des entonnoirs ciHes identiques a ceux du B. punctatus." In mature pro- glottides about six of these descending canals are seen on each surface of the strobila, as stated by Matz, those on the ventral surface, altho of varying size, being constantly the largest. The outermost of these passes ventral to the cirrus-sac, while the corresponding dorsal one is much more median in position. All of the vessels He just within or sometimes among the inner transverse mus- cles but not so much among the vitelhne follicles as Matz found. In the first segments these twelve canals become reduced to three or four, irregularly arranged on each side of the median sagittal plane, of which one or two may 196 ILLINOIS BIOLOGICAL MONOGRAPHS [484 course outside of the nerve strand for considerable stretches. Only one large vessel, just within the nerve strand, passes into the base of the scolex on each side. These two are quickly reduced in size and disappear at about the middle of the scolex. In the youngest plerocercoids, such as shown in figure 50, there was seen at the posterior end a cuticular sac or invagination about 45/1 in length by 10/i in diameter, much resembling an excretory vesicle. But since no vessels connected with this structure as in ^ . rugosum, its nature was not satisfactorily determined. On the other hand, the vessels of a young stro- bila which had evidently just lost some segments did not open on the concave posterior end but were lost in the parenchyma some distance from the end after considerable anastomosing. The earliest traces of the reproductive rudiments appear in the marine type about 45mm. from the tip of the scolex while the first eggs are to be seen in the uterus 63mm, from the same point. The same data for a considerably relaxed strobila from Coregonus chipeiformis are respectively 62 and 225mm. Olsson (1893:17) found the first testes to appear in a 200mm. strobila from Salmo alpinus 95mm. from the anterior end, while 20mm. farther the uteri began to show. Depending a great deal on the amoimt of relative contraction of the proglottides, the genital cloaca is situated from one-third to half way along the margin of the segment, altho Matz (1892:112) stated that its location v/as between the first and second thirds of the edge of the proglottis. He also said that they (? the cirrus-sacs) always opened on the left margin of the strobila; but Liihe (1899) corrected this error by stating that altho they are situated on one side for long stretches, in reality they alternate from side to side. The writer also found them to be irregularly alternating but unilateral thru many proglottides. In one strobila from a whitefish, for instance, they vrere found to be arranged as follows, the numbers representing the numbers cif proglottides in which they are on the same side before changing to the opposite margin: 16, 3, 2, 5, 41, 21, 19, 7, 7, 8, 13, 3, 4, 11, 28, 9, 7, 9, 35, 10, 26, 9, 7, 9, 35, 11; while in a stretch of gravid proglottides from Cristivomer twamaycush, the lake trout, the data are: 27, 2, 80, 4, 3, 2, 13, beyond which the cirrus-sacs had so degenerated that it was found impossible to follow them ^dth satisfaction in the toto preparations. Zschokke (1884:25) erroneously de- scribed the cirrus-pouch as being "... situee vers le milieu de la face ventrale de chaque proglottis," while "L' orifice femelle se trouve en dessous, vers le bord posterieur du proglottis," thus leading Lonnberg (1889:35) to establish the new species B. suecicus which Matz (1892:111) considered with obvious justification to be synonymous with his B. infundibuliformis, or A . crassum as it is now known. The cloaca itself is tubular, from 50 to 60/x in depth in the fresh-water from and about 175/1 in the marine form. In either case there is no sharply separated hermaphroditic duct, the cirrus and vagina opening very close together at the bottom of the pore, the latter constantly ahead of and more or less ventral to the former. Matz stated that the testes were about 300 in number, 72/t in size, and ex- tended from the median line to the lateral nerves, while Liihe (1900a) described 485] PSEUDOPHYLLIDEA FROM FISHES— COOPER 197 them as being between the uterus and the marginal nerves as in B. imbrkatus. In the present study they were found to pass to the median line and dorsal to the uterus-sac in the anterior portion of the proglottis but to be prevented from doing so posteriorly by the ovary and the ducts in its immediate neighbor- hood. They are not all in the same horizontal plane but arranged in two or three pseudostrata (Fig. 92). Their number is from 40 to 150 in each proglottis with an average of 90, and their dimensions from 95 to 115/i in depth by 70 to 100 in transverse diameter, being roughly circular in frontal sections. The vas deferens forms an elongated mass of coils of quite the same shape and ar- rangement with the fewer coils before entering the cirrus-sac as in yl. rugosum. Its dimensions are 0.35 to 0.60 by 0.15 to 0.18mm. In the proximal one-third to one-half of the cirrus-sac the male duct forms a mass of coils, the ejaculatory duct, which may or may not become enlarged with sperms to form at least a temporary inner seminal vesicle, while in the distal half of the pouch it con- tinues in an almost straight course as the cirrus proper with a maximum dia- meter of 20a£. The cirrus-sac varies in dimensions from 130 to 220 by 60 to 105)U in the fresh-water form and 255 to 380 by 120 to 150/x in the form from Salmo salar, and is ovoid in shape with the smaller end, often quite pointed, towards the genital cloaca. Matz gave the length of the cirrus-sac as 255fi for the form from the European salmon and salmon trout. The wall is com- paratively thinner and there are fewer parenchymatous nuclei around it or within it among the conspicuous retractor muscles than in A. rugosum. The vagina opens constantly ahead of the cirrus and more or less ventral to it as pointed out by Matz (p. 112). From this point it bends backward and gradually downward, thus making a bow which lies below the coils of the vas deferens, and then courses mediad parallel to the anteroventral border of the latter. Near the median line, however, it again rises to pass over the lateral border of the ovary before gaining the oviduct. There is thus a broad ventral bow to the vagina, which, contrary to Liihe's statement, is more median than in A . rugosum. Opposite the cirrus-sac the vagina may be found enlarged to a diameter of 35yu. The ovary is quite irregular or only very roughly kidney- shaped as stated by Liihe (1900a), and has a maximum diameter in the marine form of 0.8mm. by a length of O.lSmm.. As in yl. rugosum, there is a very broad isthmus, with the posterodorsal part of which the oviduct is connected by the oocapt which has a diameter of 40ju. The oviduct receives the vagina in the median coronal plane. Usually two small vitelUne ducts passing along the ventral floor of the medulla unite in the median line to form a common duct v/hich is not enlarged to form a reservoir; but in the material from Lota two others were seen to unite dorsally to form another common duct, while the ventral duct formed a number of anastomoses with its tributaries before uniting with the oviduct. Matz described the vitelline follicles as irregular in shape, discontinuous from proglottis to proglottis and located among the longi- tudinal muscles, there being about 29 "on the surface," presumably in trans- verse sections. The writer likewise found them to be quite irregular in shape and to range in location from among the inner longitudinal muscles to distinctly out- 198 ILLINOIS BIOLOGICAL MONOGRAPHS [486 side of them and even among the subcuticular nuclei in the proboscideus form. In toto mounts of anterior segments they may be seen to be quite discontinuous and, as pointed out by Llihe (1900a), arranged in two lateral fields on each surface, there being a few, however, in the median ventral line. The com- bined ootype and shell-gland is a small inconspicuous compact structure lying close to the dorsal wall of the medulla as in A . rugosum. The uterine duct also takes only a very few coils before expanding into the capacious uterus-sac. Matz described the latter as being not round as in B. scorpii and B. claviceps, but pointed towards each side, which points do not disappear when the sac is filled with eggs, while Liihe (1910:17) repeats this statement. In the material studied by the writer only the young uterus-sacs, much elongated in the transverse direction, were found to be pointed laterally, but the mature struc- tures, i.e., when filled with eggs, distinctly rounded or only very broadly pointed in some cases (Fig. 77). In doroso ventral view the sac varies in shape from an elHptical or quadrate, lobed organ, filling up most of the proglottis in the fresh- water form, to a transversely much elongated cavity in the proboscideus form, so enlarged in mature joints that the strobila in such gravid regions is little else than a tube filled with eggs. The openings are situated in the median line on the ventral surface, each one being just opposite the posterior emargin- ation of the segment immediately ahead. Matz states that the egg measures 54.5 by 40.9/x, but the writer found them of quite different sizes when removed from gravid segments in the 5% formalin solution in which they were preserved. In general, two sizes were seen, small ones with thicker darker shells and larger ones with thinner lighter shells, but at the same time all intermediate sizes between these forms. Those from the fresh- water form of the species measured 55 to 115 by 35 to 75fj,, while those from the form from Salmo salarwere 45 to 110, by 30 to 75/i, thus showing that so far as the size of the eggs goes, at least these two forms are one and the same species. So far as the writer is aware the development of the egg of this species has been studied only by Koelliker (1843:91) and later by Braun (1889:668, etc.) in review. Several writers have described various young plerocercoids. The youngest found by Olsson (1867:53) was only 2mm. in length and had only three segments, a neck and several longitudinal spiral excretory canals, of which two extended to the anterior part of the head. The triangular caudal piece of this young strobila had a median sinus posteriorly, thus indicating, perhaps, in the light of the present contributions, that a portion had already diasppeared. Leuckart (1878:605) spoke of the simplicity of the development of the plerocercoid, while Zschokke (1884:27) believed that he had found the larvae of B. infundibuliformis in numerous cysts on the outside of the walls of the ahmentary tract of Perca fluviatilis, Trutta vulgaris, Esox lucius, Salmo umbla, Thymallus vulgaris and Lota vulgaris. They were also found on the liver, the spleen, the ovaries and the peritoneum of the same fishes, with their scoHces ordinarily invaginated and with lengths of from 2 to 6mm. In 1893 Olsson again referred to the plerocercoids and younger strobilas. In Lota vul- 487] PSEUDOPHYLLIDEA FROM FISHES— COOPER 199 garis he found young strobilas, still possessing the rounded caudal piece but no neck, with the habit of invaginating their scolices. In a Salmo salar he found on July 4th similar young " scolices " (plerocercoids) not only free in large numbers in the intestine of the host posterior to the pyloric ceca but also present along with the anterior ends of adult strobilas in the ceca themselves. Again in June he found a great many young strobilas in S. alpinus. These facts, togeth- er with the further fact that the adult worms have been found in the hosts during every month of the year, points to infection of the final host with the pleroceroids at all times of the year. Of chief interest in this connection is the finding by Schneider (1902:28) of young plerocercoids 2 to 7mm. long free in the stomach and intestine of Clupea harengus membras L., which he believed to be the young stages of Bothriotaenia proboscidea (Batsch), as he called the species. They were found in greater numbers towards the latter part of June than at other times during the summer. Concerning the sig- nificance of the location of the larvae in these herring, he said: "Daher muss ich armehmen, dass dieser Fisch nicht der erste, sondern der zweite Zwischen- wirth des Bandwurmes ist. Erster Zwischenwirth, in welchem der Wurm sein Cystenstadium durchlauft, muss wohl ein Arthropode (Kruster oder Insecten- larve) sein, der dem Ostseeheringe sehr oft zur Nahrung dient. Falls meine Annahme richtig ist, woran ich nicht zweifele, das Clupea harengus membras L. derjenige Zwischenwirth ist, mit dem der Ostseelachs direct die Larven von B. proboscidea in seinen Darmkanal aufnimmt, so erklart sich leicht das Zustandekommen solcher Wasserinfectionen, wie sie an den Ostseelachsen beobachtet werden." Liihe (1910:12) briefly reviewed the findings of these bothriocephalid larvae in various hosts up to date and pointed out that those of Diphyllobothrium latum have often been confused with those of A . crassum and that in many cases it is doubtful whether either was certainly at hand. Ward (1910:1184) reported the species from Salmo salar sebago and Cristovomer namaycush, but was unable to throw any hght on the life-history altho he in- vestigated the Sebago smelt as the possible intermediate host. No larvae were found in the latter, but concerning the infection of the final host, he said: "This is worthy of note that all of these parasites were full grown; not a single specimen was found which was not discharging ripe proglottides. Consequently the infestation must have taken place somewhat earlier in the year. " The youngest lots of material studied by the writer were two taken from Lota maculosa from Lake Ontario, off Port Credit, near Toronto, on Nov. 5 and 8, 1912, and one from the intestine of a young Cristovomer namaycush from the same locality on the latter date. The lot from the lake trout con- tained all stages from that shown in figure 50 to the largest which by compari- son with adult specimens from the same host were found to belong to this species. While no stages were found between that shown in figure 52 and that shown in figure 50 altho two others were only very slightly larger than the latter, it seems reasonable to consider the latter itself to belong to this series and to represent the earliest stage of the same. Figures 53 and 54, two later stages, are given to show the manner of beginning of the segmentation and the early 200 ILUNOIS BIOLOGICAL MONOGRAPHS [488 dropping ofif of two or more very immature segments from the hinder end. The first indication of this is probably represented in figure 52, altho the strobila in figure 53 does not show it. The relative ages, however, of these two is difficult to state definitely since the first one is more contracted longitudinally than the other. On the other hand, two intermediate in length between those shown in figures 53 and 54, were indented posteriorly, thus showing that some of the earliest segments had already been lost. Thus it is seen that at a very early period in the development of the strobila of this species there are lost a few of the first-formed segments in much the same way as the bladder of the cysticercus of the taenioid cestodes is cast off in the final host. The material studied consisted of lots 86, 87, 88, 303 and 304 from Salmo salar, 38a, b, c, d, e, and o, 66, 67, 164, 167 and 192 from Cristivomer namaycushy 42 and 166 from Coregonus clupeiformis, and 61, 62, 381, and 387 from Z,o/Tionym mit Schistocephalus nodosus Rud.? Zool. Anz., 21:143-45. 1902. Sur un nouveau Bothriocephalide d'oisseau (Plychobothrium armatum). Arch. parasit., 5:440-48. 1910. Triaenophorus robustus Olsson dans les lacs Neuchatel et de Bienne. Bull. soc. sc. nat. Neuchatel, 36:86-89. Gamble, F. W. 1896. Platyhelminthes and Mesozoa. Cambridge Natural History, 2; 96 pp., 47 ill. London. Gemmill, J. F. 1909. A Specimen of Ligula simplicissinta, Rudolphi; with Notes on the Life-History of the Ligulinae. Glasgow Naturalist, 2:6-12. Gmelin, J. F. 1790. Caroli a Linne . . . Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, diflerentiis, synonymis, locis, 1:3021- 3910. Lipsiae. GoEZE, J. A. E, 1782. Versuch einer Naturgeschichte der Eingeweiderwiirmer thierischer Korper, 480 pp., 44(35) pi. Blankenburg. Grimm, O. 1871. Zur Anatomie der Binnenwiirmer. Zeit. wiss. Zool., 21 :499-504. HOFER, B. 1904. Handbuch der Fischkrankheiten. Stuttgart, 1906. Htjntsman, a. G. 1915. Fresh-Water Malacostraca of Ontario. Contrib. Can. Biol., Fasc. II, Suppl., 47th Ann. Rep. Dep. Mar. Fisheries. Ottawa, Canada. JanickIj C. V. 1906. Studien an Saugethiercestoden. Zeit. wiss. Zool, 81:505-97, 6 pi. Johnstone, J. 1907. Internal Parasites and Diseased Conditions of Fishes. Trans. Biol. Soc. Liver- pool, 21:170-203. 1909. Internal Parasites and Diseased Conditions of Fishes. Trans. Biol. Soc. Liver- pool, 32:87-100. Kessler, K.. T. *1868. Beitrage zur zoologischen Kenntnis des Onegasees und dessen Umgebung. Beil. Arb. russ. naturf. Vers. Petersburg, 1868, 183 pp., 8 pi. [Russian text.] KlESSLtNG, F. 1882. Ueber den Bau von Schistocephalus dimorphus Creplin und Ligula simplicissima Rudolphi. Arch. Naturg., 1 :241-80, pi. 14-15. 204 ILUNOIS BIOLOGICAL MONOGRAPHS [492 KOELLIKER, R. A. VON 1843. Beitrage zur Entwickelunggeschichte wirbelloser Thiere. Arch. Anat., Physiol., wissensch. Med., p. 68-141, pi. 6-7. Krabbe, H. 1865. 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Fauna Arct., 3; 31 pp., 2 pi. 1903a. Marine Schmarotaer in Siisswasserfischen. Verh. naturf. Ges. Basel. 16:118- 57, 2 pi. 499] PSEUDOPHYLLIDEAN CESTODES FROM FISHES— COOPER 211 EXPLANATION OF PLATES ABBREVIATIONS be bothrial cavity ns nerve strand bo bothrial opening 0 ovary bs bothrial sphincter oc oocapt c cirrus od oviduct cm circular muscles ot ootype cs cirrus-sac p proboscis cu cuticula rs receptaculum seminis cvd common vitelline duct s subcuticula dh hermaphroditic duct t testis dm dorsoventral muscles td terminal disc ec excretory canal tm transverse muscles ed ejaculatory duct tid uterine duct ev excretory vesicle uo uterus opening fa female atrium lis uterus sac fd fertilization duct ut uterus g genitaha V vagina g<^ genital atrium vb vestibule gc ganglionic cells vd vas deferens to isthmus of ovary vg vitelline glands Im longitudinal muscles vo vaginal opening nc nerve commissure vs vesicula seminalis The lines in the figures have the following values: 0.05mm. in figures 63, 67, 105, 106, 107, 108; 0.2mm. in figures 14, 17, 18, 88, 94, 97, 99, 101; and 0.5mm. in all other figures, unless otherwise stated in the explanation of the figure. 212 ILLINOIS BIOLOGICAL MONOGRAPHS [500 EXPLANATION OF PLATE Fig. 1. Ligula intestinalis, anterior end of larva, showing scolex. Fig. 2. Ligula inlestindis, anterior end of adult. Fig. 3. Schisiocephahis solidus, anterior end of larva. Fig. 4. Marsipometra hastata, scolex, surficial view. Fig. 5. Marsipometra hastata, same specimen, lateral view. Fig. 6. Bothrimonus intermedins, scolex, surficial view. Fig. 7. Bothrimonus intermedins, same specimen, lateral view. Fig. 8. Bothrimonus intermedins, same specimen, terminal view. Fig. 9. Baplobolhrinm globuJiforme, secondary scolex, surficial view. Fig. 10. Haplobothrium globuliforme, same specimen, lateral view. Fig. 11. Cyaihocephalus americanus, scolex, toto preparation. Fig. 12. Triaenophorus, larva, robustus ty-pe, surficial view. Fig. 13. Triaenophorus, same specimen, lateral view. Fig. 14. Triaenophorus, same specimen, one of the tridents of hooks. Fig. 15. Triaenophorus, larva, nodulosus type, surficial view. Fig. 16. Triaenophorus, same specimen, lateral view. Fig. 17. Triaenophorus, same specimen, a trident, terminal view. Fig. 18. Triaenophorus, same specimen, surficial view. Fig. 19. Bothriocephalus claviceps from Eupomotis gibbosus, scolex, surficial view. Fig. 20. Bothriocephalus claviceps, same specimen, lateral view. Fig. 21. Bothriocephalus scorpii, scolex, surficial view. Fig. 22. Bothriocephalus scorpii, same specimen, lateral view. Fig. 23. Bothriocephalus claviceps from Anguilla rostrata, scolex, surficial view. Fig. 24. Bothriocephalus cuspidatus, scolex, surficial view. Fig. 25. Bothriocephalus cuspidatus, same specimen, lateral view. Fig. 26. Bothriocephalus manubriformis, scolex, surficial view. Fig. 27. Bothriocephalus manubriformis, same specimen, lateral view. Fig. 28. Bothriocephalus occidentaUs, scolex. After Linton. Fig. 29. Clestobothrium crassiceps, scolex, surficial view. Fig. 30. Clestobothrium crassiceps, same specimen, lateral view. Fig. 31. Clestobothrium crassiceps, same specimen, terminal view. Fig. 32. Abothrium rugosum, scolex of young strobila. Fig. 33. A bothrium rugosum, later stage in degeneration of same. Fig. 34. Abothrium rugosum, still later stage. Fig. 35. Abothrium rugosum, pseudoscolex from lumen of pyloric coecum of host. Fig. 36. Abothrium rugosum, pseudoscolex from wall of coecum. Fig. 37. A bothrium crassum, scolex from Cristivomer namaycush. Fig, 38. Abothrium crassum, enlarged scolex from Lota maculosa. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV COOPER PSEUDOPHYLLIDEAN CESTODES PLATE I sou PSEU DOPEY LLI DEAN CESTODES FROM FISHES— COOPER 213 PLATE II 214 ILLINOIS BIOLOGICAL MONOGRAPHS [502 EXPLANATION OF PLATE Fig. 39. A bothrium crassunl, scolex of specimen from Salmo solar, surficial view. Fig. 40. Abothrium crassum, same specimen, lateral view. Fig. 41. Abothrium crassum, young scolex from Lota maculosa. Fig. 42. Abothrium crassum, same specimen, lateral view. Fig. 43. Haplobothrium globuliforme, primary scolex, toto preparation. Fig. 44. Haplobothrium globuliforme, primary strobila, toto preparation. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 39 40 fk M m COOPER PSEUDOPHYLLIDEAN CESTODES PLATE II 503] PSEUDOPHYLLIDEAN CESTODES FROM FISHES— COOPER 215 PLATE III 216 ILLINOIS BIOLOGICAL MONOGRAPHS [504 EXPLANATION OF PLATE Fig. 45. Bothrimonus intermedius, scolex and anterior end, toto preparation, showing fore- most sets of genitalia. Fig. 46. Marsipometra hastata, plerocercoid, siirficial view. Fig. 47. Marsipometra hastata, older plerocercoid, surficial view. Fig. 48. Clestobothrium crassiceps, toto of scolex and anterior end. Fig. 49. Clestobothrium crassiceps, toto of young strobila, surficial vi ew. Fig. 50. Abothrium crassum, plerocercoid from Cristivomer namaycush, surficial view. Fig. 51. Abothrium crassum, same specimen, lateral view. Fig. 52. Abothrium crassum, young strobila from same host. Fig. 53. Abothrium crassum, older strobila from same host. Fig. 54. Abothrium crassum, still older strobila, showing dropping off of segments posteriorly. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV z. lif* 50 49 r k~. 51 52 COOPER PSEUDOPHYLLIDEAN CESTODES PLATE III 505] PSEU DOPEY LLIDEAN CESTODES FROM FISHES— COOPER 217 PLATE IV 218 ILLINOIS BIOLOGICAL MONOGRAPHS [506 EXPLANATION OF PLATE Fig. 55. Botkriocephalus scorpii, three anterior primary segments, to to preparation. The stars at the side indicate the extent of the segments. Fig. 56. Botkriocephalus scorpii, one farther back, also toto. Fig. 57. Botkriocephalus scorpii, another, showing reproductive rudiments. Fig. 58. Clestohotkrium crassiceps, primary segment with reproductive rudiments, toto preparation. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV Wii' 08 COOPER PSEUDOPHYLLIDEAN CESTODES PLATE IV 507] PSEU DOPEY LLI DEAN CESTODES FROM FISHES— COOPER 219 PLATE V 220 ILLINOIS BIOLOGICAL MONOGRAPHS [508 EXPLANATION OF PLATE Fig. 59. Boihriocephalus scorpii, outline of mature segments. Fig. 60. Boihriocephalus scorpii, toto of same specimen. Fig. 6L Boihriocephalus scorpii, portion of strobila showing excretory vessels. Fig. 62. Boihriocephalus manubriformis, anterior primary segment. Fig. 63. Abolhrium rugosum, terminal excretory vesicle. Fig. 64. Abolhrium crassum, anterior segments of strobila from Coregonus clupeiformis, toto. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV COOPER PSEUDOPHYLLIDEAN CESTODES PLATE V 509] PSEUDOPHYLLIDEAN CESTODES FROM FISHES— COOPER 221 PLATE VI 222 ILUNOIS BIOLOGICAL MONOGRAPHS [510 EXPLANATION OF PLATE Fig. 65. Eaplohothrium globvliforme, transection thru primary scolex. Fig. 66. Eaplohothrium globidiforme, transection thru the ganglionic mass behind the. pro- boscides. The reference line is 0.1mm. long. Fig. 67. Haplobothrium glohdiforme, transection thru a single proboscis bulb. Fig. 68. Marsipomeira hastaia, toto of ripe proglottis. Fig. 69. Botkriocephalus cuspidaius, transection thru an anterior segment. Fig. 70. Botkriocephalus cuspidatus, toto of ripe proglottides, posterior in deeper optical section. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 67 ns 69 70 COOPER PSEUDOPHYLLIDEAN CESTODES PLATE VI 511] PSEU DOPEY LLI DEAN CESTODES FROM FISHES— COOPER 223 PLATE VII 224 ILLINOIS BIOLOGICAL MONOGRAPHS 1512 EXPLANATION OF PLATE Fig. 71. Bolhriocephaliis scorpii, toto of two segments. Fig. 72. Bothriocephalus davkcps from Eupomolis gibbosus, toto of mature proglottides. Fig. 73. Bothriocephalus manubrifonnis, toto of mature proglottides. Fig. 74. Clcstobothrium crassiceps, segments showing spurious articulations. Fig. 75. Clestobothrium crasskeps, toto of mature proglottis. Fig. 76. Abothrium rugosum, frontal section of mature proglottis. Fig. 77. Abothrium crassum, Xolo oi n^e. proglottis of strobila from CorfgoM«5 clupeiformis. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 77 us 73 0 uo 75 72 74 uo us ■Aa • ... - vi_ COOPER PSEUDOPH\TLLIDEAN CESTODES PLATE VII 513] PSEUDOPHYLLIDEAN CESTODES FROM FISHES— COOPER 225 PLATE VIII 226 ILLINOIS BIOLOGICAL MONOGRAPHS (514 EXPLANATION OF PLATE Fig. 78. Ligula inlestinalis, median portion of a transection thru the genital cloaca. Fig. 79. Schislocephalus solidus, median jxtrtion of transection thru ovary. Fig. 80. Schislocephalus solidus, median portion of transection thru the seminal vesicle and cirrus-sac. The reference line is 0.3mm. long. Fig. 81. Bothrimonus intermedius, transection thru the ovarian isthmus. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 79 W^^m^M^ SI ns vs cs '■'J%^ '"^^Mlm^ -• 1 I I COOPER PSEUDOPHYLLIDEAN CESTODES PLATE VIII 51SI PSEU DOPEY LUDEAN CESTODES FROM FISHES— COOPER 227 PLATE IX 228 ILLINOIS BIOLOGICAL MONOGRAPHS [516 EXPLANATION OF PLATE Fig. 82. Cyathocephalus amerkanus, transection thru ovarian isthmus. Fig. 83. Marsipometra hastata, transection thru ovarian isthmus. Fig. 84. Bothriocephalus scorpii, transection thru ovary. Fig. 85. Bothriocephalus claviceps from Eupomolis gihbosus, transection thru ovary. Fig. 86. Bothriocephalus cuspidatus, transection thru ovary of mature proglottis. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV ns ns 84 CXX)PER PSEUDOPHYLLIDEAN CESTODES PLATE IX 517] PSEU DOPEY LLIDEAN CESTODES FROM FISHES— COOPER 229 PLATE X 230 ILLOINIS BIOLOGICAL MONOGRAPHS [SIS EXPLANATION OF PLATE Fig. 87. Bothriocephalus manubriformif , transection thru anterior region. Fig. 88. Bothriocephalus manubrifortnis , cirrus-sac and vaginal bulb from a transection. Fig. 89. Bothriocephalus occidentalis, cirrus-sac from a transection. The reference line is 0.1mm. long. Fig. 90. Clestobothrium crassiceps, transection thru the ovary. Fig. 91. Abotkrium rugosum, transection thru the ovary. Fig. 92. Abotkrium crassum, transection thru the ovary of a specimen from Sdmo solar. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV COOPER PSEUDOPHYLLIDEAN CESTODES PLATE X 5191 PSEU DOPEY LU DEAN CESTODES FROM FISHES-COOPER 231 PLATE XI 232 ILLINOIS BIOLOGICAL MONOGRAPHS [520 EXPLANATION OF PLATE Fig. 93. Cyathocephalus anuricanus, frontal section of ripe proglottis. Fig. 94. Bothrimonus intermeditis, median sagittal section. Fig. 95. Bothriocephalus scorpii, median sagittal section, composite. The reference line is 0.3mm. long. Fig. 96. Bothriocephalus daviceps from Eupomotis gibbosus, median sagittal section. Fig. 97. Bothriocephalus manubriformis, transection thru uterus opening. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV vd cs 97 Vc;^ Mt)) L •- 93 94 COOPER PSEUDOPHYLLIDEAN CESTODES PLATE XI 521] PSEUDOPHILUDEAN CESTODES FROM FISHES— COOPER 233 PLATE XII 234 ILUNOIS BIOLOGICAL MONOGRAPHS [522 EXPLANATION OF PLATE Fig. 98. Ligula intestinaits , union of vagina and vitelline duct with oviduct. The reference line is O.lnim. long. Fig. 99. Cyathocephalus amerkanus, oocapt containing an ovum. Fig. 100. Marsipomelra haslala, genital cloaca from frontal section. Fig. 101. Marsipomelra haslala, cirrus sac from a transection. Fig. 102. Bothriocephalus cuspidalus, median sagittal section, composite. Fig. 103. Clcslobotkrium crassiceps, median sagittal section, composite. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 103 102 98 cvd 100 uo 101 oc COOPER PSEUDOPHYLLIDEAN CESTODES PLATE XII 5231 PSEU DOPEY LLIDEAN CESTODES FROM FISHES— COOPER 235 PLATE XIII 236 ILLINOIS BIOLOGICAL MONOGRAPHS 1524 EXPLANATION OF PLATE Fig. 104. Cyaihocephalus americanus, diagram of median sagittal section. Fig. 105. Bothriocephalus scorpii, portion of section, showing union of vagina with oviduct. Fig. 106. Bothriocephalus cuspidatus, young egg, showing an early stage in development, drawn from life. Fig. 107. Bothriocephalus cuspidatus, older egg, many-celled stage. Pig. 108. Clestobothrium crassiceps, four consecutive sections thru union of vagina and ovi- duct, showing the receptaculum seminis. Fig. 109. Abothrium rugosum, union of vagina and common vitelline duct with oviduct. The reference line is 0.02nim. long. ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME IV 108 104 109 105 cvd 107 106 COOPER PSEUDOPHYLLIDEAN CESTODES PLATE XIII 525] PSEUDOPHYLLIDEA FROM FISHES— COOPER 237 INDEX OF HOSTS Abramis bjorkna, 23 blicca, 23 brama, 21 vimba, 23 Acipenser oxyrhynchus, 64 ruthenus, 99 sturio, 64 Alburnus albumus, 23 lucidus, 21 Alca pica, 34 torda, 33 Alosa ohiensis, 21 Ambloplites rupestris, 22 Ambystoma sp., 22 tigrinum, 22 Ameiurus, 21 Amia, 71 Amia calva, 45 Amoetes branchialis, 23 Anas boschas fera, 22 glacialis, 33 Anguilla acutirostris, 116 anguilla, 116 migratoria, 116 rostrata, 116 vulgaris, 99, 116 Aquila chrysaetus, 22 Ardea alba, 23 ciconia, 23 cinerea, 34 egretts, 23 nycticorax, 22 stellaris, 33 Arnoglossus boscii, 98 pegosa, 98 solea, 98 Aspius alburaus, 23 rapax, 21 Atherina mocho, 21 B Bass, white, 87 Blicca bjorkna, 21 Bothus maculatus, 99 Brochet, 83 C Carassius carassius, 23 gibelio, 21 vulgaris, 23 Catostomus aniens, 21 commersonii, 25, 85, 87 commersonii commersonii, 22 latipinnis, 21 Chondrostoma nasus, 21 Ciconia alba, 22, 33 ciconia, 23, 34 nigra, 34 Clupea harengus, 189 harengus membras, 199 Cobitis aculeata, 23 taenia, 21 Colymbus arcticus, 22, 34 auritus, 23 cristatus, 23, 34 glacialis, 34 griseigena, 23, 34 hoelbeelli, 23 immer, 34 rubricoUis, 23 septentrionalis, 33 subcristatus, 23 troile, 34 Coregenus albula, 83 clupeiformis, 54, 189 fera, 188 lavaretus, 83, 188 oxyrhynchus maraena, 189 wartmanni, 21 Corvus corax, 34 comix, 22, 33 Cottus bairdii, 33 bubalis, 98 poecilopus, 33 quadricomis, 98 scorpio, 33 scorpius, 97, 98 Cristi vomer namaycush, 189 Cyprinus albumus, 21 blicca, 23 brama, 23 carassius, 23 gobelio, 23 lacustris, 23 leuciscus, 23 tinea, 23 238 ILLINOIS BIOLOGICAL MONOGRAPHS [526 D Decapterus punctatus, 99 E Esox lucius, 21, 83, 84, 86, 189 masquinongy, 85, 87 Eupomotis gibbosus, 116 F Falco albici!la, 22 chrysaetos, 23 tulvTjs, 23 Fulica atra, Zi Fuligula clangula, 22 marila, i3 G Gadidae, 178 Gadus aeglifinus, 98, 173 callarias, 173, 174 euxinus, 155 Iota, 173 merluccius, 155, 173 minutus, 98 morrhua, 173, 174 morrua, 183 mustela, 173 pollachius, 174 Gammarus pulex, 61 Gasterosteus aculeatus, 2>i bispinosus, 116 bispinosus atkinsii, 22, 33 cataphractus, 2>i pungitius, a Gobio fluviatilis, 23 gobio, 21 vulgaris, 21 Graculus carbo, 22 H Haematopus ostrealegus, 3i Hake, small, 155 Haliaetus albicilla, 22 Harelda glacialis, ii Hemitripterus americana, 99, 100 Herodias alba, 22 Herring, lake, 86 Hiodon alosoides, 124 tergisus, 124 Hippoglossus hippoglossus, 99 Histiophonis gladius, 134, 146 sp., 134 Hybognathus nuchalis, 21 Hydrochelidon nigra, 22 I Istiophorus nigricans, 134 L Labrus maculatus, 99 Larus argentatus, 22, 34 canus, 23 capistranus, 34 marinus, 34 melanocephalus, 23 parasiticus, 23 pelecanus carbonis, 23 pygmaei, 23 ridibundus, iZ tridactylus, 23 Leucichthys artedi, 83, 84, 86 Leuciscus erythrophthalmus, 23 leuciscus, 23 phoxinus, 23 pulchellus, 23 nitilis, 21 vulgaris, 23 I-imanda ferruginea, 99 Lophodytes cucullatus, 33 Lophopsetta maculata, 99 Lota, 178 Lota lota, 189 maculosa, 41, 86, 189, 194 molva, 183 vulgaris, 99, 174, 189 Lucioperca lucioperca, 23 Sandra, 21 M Melanogrammus aeglifinus, 174 Merganser, 22 Merganser merganser, 23, 34 sp., 23 Mergus albellus, 23, 34 merganser, 22 minutus, 23 serrator, 22, 33 Merlangus carbonarius, 155, 174 pollachius, 183 sp., 155 Merluccius bilinearis, 112, 155, 170 esculentus, 155 merluccius, 155 vulgaris, 155, 174 Microgadus tomcod, 63, 174 Micropterus dolomieu, 22, 85, 87 Mola, 91 Mola mola, 92 Morrhua aeglifinus, 174 americana, 21 vulgaris, 174 Motella mustela, 99, 183 MuUus barbatus, 99 Muraena anguilla, 1 16 cassini, 116 527] PSEUDOPHYLLIDEA FROM FISHES-COOPER 239 Myoxocephalus aeneus, 99, 100 groenlandicus, 100 octodecimspinosus, 99 N Nemachilus strauchi, 21 Notropis cayuga, 22 cornutus, 21, 22 delicatus, 87 hudsonius, 22 Nycticorax nycticorax, 22 NjToca marila, 33 O Osmerus mordax, 21 operlanus, 189 Paralichthys dentatus, 99 oblongus, 99 Palinurichthys perciformis, 99 Perca flavescens, 22, 87, 124 fluviatilis, 21, 189 Percina caprodes, 124 Petromyzon branchialis, 21 Phoca vitulina, 21, 33 Pickerel, 124 Platessa flesus, 98 passer, 98 plana, 98 Pleuronectes boscius, 98 flesus, 98 maximus, 98 rhombus, 98 solea, 98 Podiceps auritus, 22 cristatus, 24, 34 minor, 23 nigricollis, H rubricollis, 23, 34 Podilymbus podiceps, 23 Polyodon, 71 Polyodon spathula, 72 Pomatomus saltatrix, 155 Pomolobus aestivalis, 170 Pontoporeia hoyi, 61 Poronotus triacanthus, 112 Psetta maxima, 98 Pseudopleuronectes americanus, 64, 99 Puffinus kuhli, 33 R Raja clavata, 99 Rana esculenta, 33 Recurvirostra avocetta, 33 Rhombus barbue, 99 laevis, 99 maximus, 98, 99 moeoticus, 99 Rhynchichthys gronovii, 3i Rissa tridactyla, 22 Rock cod, 149 S Salmo alipinus, 188 carpio, 188 caspius, 188 fario, 188 hucho, 188 lacustris, 188 namaycush, 188 salar, 2,2,, 113, 183, 187, 188, 189, 194 salaris, 190 salar nobilis, 188 salar sebago, 188 salvelinus, 21, 188 siscowet, 188 thymallus, 188 thymallus vexillifer, 188 trutta, 188 umbia, 188 Salvelinus fontinalis, 189 Scardinius erythrophthalmus, 21 Schizopygopsis kozlovi, 21 Scomber scomber, 100 Scorpaena porcus, 99, 113 scrofa, 112 Scyllium canicula, 163 Sebastodes sp., 149 Siluris glanis, 21 Solea monochii, 99 Squalius cephalus, 21 turcicus, 23 Stercorarius parasitica, 22, 33 Sterna arctica, 34 hirundo, 22, 33 macroura, 34 minuta, 34 nigra, 23, 34 Stizostedion canadense, 85, 87, 124 vitreum, 86, 87, 124 Sunfish, 91 T Tarpon atlanticus, 134, 145 Tetrapterus albidus, 134 belone, 134 imperator, 134 sp., 145 Thymallus vulgaris, 189 Tinea vulgaris, 21 Torpedo ocellata, 98 240 ILLINOIS BIOLOGICAL MONOGRAPHS [528 Totanus calidrus, 33 chloropus, 23 Trachurops crumenophthalmus, 100 Trigla adriatica, 98 lineata, 98 Trout, 189 Trutta fario, 189 lacustris, 189 salar, 189 trutta, 189 variabilis, 189 vulgaris, 198 u Uria grylle, 34 troile, 33 Uranidea formosa, 33 Urinator arcticus, 22, 33 stellatus, 23 Urophycis chuss, 100 tenuis, 174 X Xema minutum, 22 ridibundum, 23 Xiphias gladius, 91 529] PSEUDOPHYLLIDEA FROM FISHES-COOPER 241 INDEX Abothrium, 171, 176 Abothrium crassum, 12, 78, 176 186 gadi, 172 nigosum, 12, 74, 172, 193 Acanthocephala, 51 Acanthophallidae, 15 Acrobothrium, 53 Alyselminthus, 95 AJyselminthus bipunctatus, 96 Amphicotyle, 171 Amphicotvle heteropleura, 159, 193 Amphicotylinae, 12 171 Amphitretidae, 15 Anchistrocephalus, 70 Anonchocephalus, 70 Aprocta, 9 6 Bothriudium, 16, 70 Bothridium pithonis, 16 Bothrimonus, 11, 62 Bothrimonus cohaerens, 64 fallax, 64, 66 intermedius, 11, 63 nylandicus, 60, 63, 64 pachycephalus, 60, 64 sturionis, 62, 64 Bothriocephalidae, 9 Bothriocephalidea, 9 Bothriocephalus, 95 Bothriocephalus affinis, 113 angustalus, 114 bipunctatus, 96 daviceps, 12, 101, 198, 114 crassiceps, 154 cuspidatus, 12, 94, 123, 135, 195 dubius, 101 du Saumon, 186 tasciatus, 101 gadi merluccii, 163 histiophorus, 133, 147 imbricatus, 197 inlundibuliformis, 185, 186 laciniatus, 133, 145, 150 manubriformis, 12, 133, 145, 147, 149 neglectus, 158 nodosus, 31 occidentalis, 12. 145, 149 pilula, 154 plicatus, 89 Droboscideus, 176, 186 punctatus, 96, 112, 118, 195 punctatus forma bubalidis, 96 forma cottiquadricornis, 96 forma motellae, 96 forma punctatus vol typica, 96 forma rhombi, 96 rugosus, 172 sagittatus, 184 sabnonis umblae, 186 scorpii, 12, 43, 49, 93, 96, 112, 119, 125, 135, 152, 159, 193 scorpii forma bubalidis, 112 forma motellae, 112 semiligula, 19 solidus, 30 spiraliceps, 164 suecicus, 186 truncatus, 89 variabilis, 101 zschokkei, 31 Bothriotaenia, 70, 88, 184 Bothriotaenia gadi, 184 hastata, 71 infundibuliformis, 186 plicata, 89 proboscidea, 183, 186 rugosa, 172 C Caryophyllaeidae, 7, 13 Cephalocotylea, 9, 62 Cephalocotyleum, 53 Ceatoda, 10 Cestodaria, 10 Cestodes, 9 Clestobothrium, 12, 153 Clestobothrium crassiceps, 12, 65, 94, 103, 140, 154 Cyathocephalinae, 11, 53, 88 Cyathocephalus, 11, 53, 70 Cyathocephalus americanus, 11, 53, 66 catenatus, 56 truncatus, 42, 53 Cj^ticercus, 81 Cysticercus fasciolaris, 170 242 ILLINOIS BIOLOGICAL MONOGRAPHS [540 D Dibothriocephalinae, 88 Dibothriorhynchus ruficollis, 51 Dibothrium, 17, 70, 88, 95, 153, 171 Dibothrium angustatum, 112 belones, 163 clavireps, 114 crassiceps, 154 hastatum, 71 heteropleurum, 159 infundibuliforme, 186 laciniatum, 133, 145, 1-^7 ligula, 18, 19, 31 manubriforme, 133 microcephalum, 101 occidentale, 149 plicatum, 89, 136 proboscideum, 186 punctatum, 96 rugosum, 172 Dibothrius, 95, 153 Diphyllobothriidae, 11, 15, 93 Diphyllobothriinae, 42, 70 Diphyllobothrium, 70 Diphyllobothrium latum, 15, 42, 80, 199 Diplocotyle, 62 Diplocotyle cohaerens, 64 olrikii, 64 rudolphii, 56, 6^ serrata, 6^ Disymphytobothriiun, 62 E Echinococcifer, 14 EchinorhjTichus, 53 Echinorhynchus xiphiae, 89 F Fasciola, 17, 30 Fasciola abdominalis, 18 hepatica, 30 intestinalis, 18 Fimbriaria fasciolaris, 107 Fistulicola, 11, 88 Fistulicola plicatus, 11, 89 Gymnobothria, 9 H Haematoloechus asper, 161 Halysls, 30 Halysis lanceolato nodosa, 31 Haplobothriinae, 11, 13, 15, 42, 70 Haplobothrium, 11, 13, 15, 43, 71, 93 Haplobothrium globulifonne, 7, 11 15 44 74. 104, 160, 195 ' ' Hirudo, 30 Hirudo depressa alba, 30 L Ligula, 17, 42 Ligula abdominalis, 18 abdominalis albumi, 18 abdominalis bramae, 18 abdominalis carassii, 18 abdominalis cobitidis, 18 abdominalis cjprinorum, 18 abdominalis gobionis, 18 abdominalis leucisci, 18 abdominalis trincae, 18 abdominalis vimbae, 18 acuminata, 18 alburni, 18 alternans, 19 avium, 18, 19 bramae, 18 carassii, 18 catostomi, 18 cingulum, 18 cobitidis, 18 colymbi, 18, 19 constringens, \S contortrix, 18 crispa, 18 digramma, 18, 19 edulis, 18 gobionis, 18 interrupta, 19 intestinalis, 11, 17, 18, 19,39 leucisci, 18 monogramma, 18, 19 nodosa, 19 petromyzontis, 18 piscium, 18 reptans, 19 salvelini, 18 simplicissima, 18, 19 sparsa, 19 trincae, 18 uniserialis, 19 vimbae, 18 Ligulinae, 11, 16. 70,88 M Marsipometra, 12, 16, 70, 93 Marsipometra hastata, 7, 12, 71 Marsipometrinae, 12, 15, 70 Monobothrium, 53 Nemertini, 51 N 541] PSEUDOPHYLLIDEA FROM FISHES— COOPER 243 Proteocephalus, 163 Pseudophyllidea, 13, 15, 118 Ptychobothriidae, 12, 15, 43, 70, 79, 93, 166 Ptychobothriinae, 12, 80, 94 R Rhytelminthus, 81, 95 Rhytelminthus anguillae, 114 Rhytis, 30, 81, 95, 171 Rhytis bipunctata, 96 claviceps, 114 conoceps, 172 salvelini, 186 solida, 30 S Schistocephalus, 8, 11, 17, 26, 30, 42, 137 Schistocephalus dimorphus, 9, 31 gasterostei, 31 nodosus, 31 rhynchichthydis, 31 solidus, 11, 24, 30, 31 zschokkei, 31 Schistorhynchus dimorphus, Scolex polymorphus, 133 Scyphocephalus, 16 T Taenia, 17, 18, 30, 53, 81, 88, 95, 171 Taeniae, 105 Taenia acutissima, 30 anguillae, 114 capitata, 18 capite truncate, 186 cingulum, 18 claviceps, 114 crassa, 186 decimpoUicaris, 172 gasterostei, 30, 31 haeruca, 89 lata, 30 lanceolata nodosa, 31 lanceolata var. ^ 31, nodularis, 31 proboscidea, 186 proboscis suilla, 186 punctata, 96 rugosa, 172 salmonis, 186 salvelini, 186 scorpii, 96 solida, 30 tetragonoceps, 172, 186 truncata, 57 Taenioidea, 51 Tetraphyllidea, 51 Tetrarhynchus, 51 Tetrarhynchus longicollis, 51 Triaenophorinae, 10, 11, 16, 45, 70, 81 Triaenophorus, 11, 42, 70, 81, 82 Triaenophorus nodulosus, 80, 82 robustus, 82 Tricuspidaria, 81 Trypanorhyncha, 13, 42, 45 V Vermis multimembris, 114 multimembris rhombi, 96 Vesicaria, 81 ILLINOIS BIOLOGICAL MONOGRAPHS PUBLISHED QUARTERLY UNDER THE AUSPICES OF THE GRADUATE SCHOOL BY THE UNIVERSITY OF ILLINOIS VOLUME IV Urbana, Illinois 1918-1919 Editorial Committee Stephen Alfred Forbes William Trelease Henry Baldwin Ward TABLE OF CONTENTS VOLUME IV MtnCBXBS FAOIS 1 Life History Studies on Moatasa Trematodes. By Ernest Carroll Faudt. With 9 platea and one text figure 1-120 (Distributed March 6, 1918) 2 The Goldfish {Carassius carassius) as a Test Animal in the Study of Toxicity. By Edwin B. Powers. With graphs and tables 121-194 (Distributed July 28, 1918) 3 Morphology and Biology of Some Turbellaria from the Mississippi Basin. By Ruth Higley. With 3 plates 195-288 (Distributed December 31, 1918) 4 North American Pseudophyllidean Cestodes from Fishes. By Arthur Reuben Cooper. With 13 plates 288-5^2 (Distributed May 31, 1919) AY 5 1977 PLEASE DO NOT REMOVE CARDS OR SLIPS FROM THIS POCKET UNIVERSITY OF TORONTO LIBRARY QL Cooper, Arthur Reuben 391 North i\merican pseudophyl- C4C75 lidean cestodes from fishes Hygiene