Life Sciences Contribution Royal Ontario Museum 1 O7 Redescription of Type Specimens of the Bryozoan Heterotrypa from Upper Ordovician Rocks of the Credit River Valley, Ontario, Canada Madeleine A. Fritz ROM ‘be eg J + . o.2@ may cht 2 en = ash! te mn ng a re ' “a “Pa iy yi Ne Digitized by the Internet Archive | in 2011 with funding from University of Toronto ere BP 8 ee fi Many 0 Pag “uy >. ee are Se es or teint es ee a Be Si de i bas’ pela Na rt ay s : _ " Se ¥r : 4 d * a, eat § Moe af hs 43 ’ : : , SN emesis (ne Oras " Ara es sees ,] Povy Pea ee 5 ‘ Ge 7 ca.) - http://www.archive.org/details/redescriptionofOOfrit . eS .*) Ve ae LIFE SCIENCES CONTRIBUTIONS ROYAL ONTARIO MUSEUM NUMBER 101 MADELEINE A. FRITZ Redescription of Type Specimens of the Bryozoan Heterotrypa from Upper Ordovician Rocks of the Credit River Valley, Ontario, Canada Publication date: 25 January 1975 ISBN 0-88854-169-4 Suggested citation: Life Sci. Contr., Roy. Ont. Mus. ROYAL ONTARIO MUSEUM PUBLICATIONS. IN. LIFE, SCIENCES The Royal Ontario Museum publishes three series in the Life Sciences: LIFE SCIENCES CONTRIBUTIONS, a numbered series of original scientific publi- cations, including monographic works. LIFE SCIENCES OCCASIONAL PAPERS, a numbered series of original scientific publications, primarily short and usually of taxonomic significance. LIFE SCIENCES MISCELLANEOUS PUBLICATIONS, an unnumbered series of publications of varied subject matter and format. All manuscripts considered for publication are subject to the scrutiny and editorial policies of the Life Sciences Editorial Board, and to review by persons outside the Museum staff who are authorities in the particular field involved. LIFE SCIENCES EDITORIAL BOARD Chairman: WALTER M. TOVELL Editor: J.C. BARLOW Associate Editor: A. R. EMERY Associate Editor: D. W. BARR MADELEINE A. FRITZ is a Research Associate in the Department of Invertebrate Palaeontology, Royal Ontario Museum, Toronto, Ontario. PRICE: $1.75 © The Royal Ontario Museum, 1975 100 Queen’s Park, Toronto, Canada PRINTED AND BOUND IN CANADA AT THE BRYANT PRESS LIMITED Redescription of Type Specimens of the Bryozoan Heterotrypa from Upper Ordovician Rocks of the Credit River Valley, Ontario, Canada Abstract Dyer (1925) described three new species and two new varieties of Heterotrypa from the Upper Ordovician rocks outcropping in the valley of the Credit River some 20 miles west of Toronto, Ontario. These types, located in the Department of Invertebrate Palaeontology of the Royal Ontario Museum, are redescribed, using qualitative and quantitative analyses and improved illustrations. In addition, data for Ulrich’s type of H. prolifica as given by Utgaard and Perry (1964) were used for comparison with Dyer’s plesiotype of that species. Introduction The Upper Ordovician rocks that underlie Toronto and vicinity are included in the Georgian Bay Formation (Liberty, 1969). Before 1969 two formations were recognized, namely, Dundas (Parks, 1924) and Meaford (Foerste, 1924). These two formations were correlated respectively with the Maysville and Richmond of Ohio. The Meaford Formation was divided by Dyer into three members in de- scending order: Meadowvale, Streetsville, and Erindale. The rich, well-preserved bryozoan fauna contained in these rocks was first described by Parks and Dyer (1922) and Dyer (1925). Armstrong (1945) restudied some of the Parks and Dyer species as part of a revision of the genus Stigmatella. Because the descriptions of these early investigators do not meet present standards, I began in 1969 a study of the type specimens designated by the above authors and located in the Department. of Invertebrate Palaeontology of the Royal Ontario Museum (Fritz, 1970, 1971, 1973). The more detailed descriptions resulting from this study should serve as a basis for work in the future, when further systematic collecting will most certainly reveal species at present unknown. Furthermore, this increased knowledge of the fauna will permit closer comparison with similar assemblages known elsewhere than has hitherto been possible. Materials and Methods The type specimens of the following taxa constitute the material dealt with herein: Heterotrypa definita Dyer, 1925 Heterotrypa prolifica (Ulrich, 1890) (determined here to be H. [Atactopora] sub- ramosa Ulrich, 1879) Heterotrypa robusta Dyer, 1925 Heterotrypa simplex Dyer, 1925 Heterotrypa simplex maculosa Dyer, 1925 (considered here to be a new species, H. maculosa) Heterotrypa subpulchella parvulipora Dyer, 1925 (considered here to represent a new species H. meafordensis Fritz, new status). In addition, data of H. prolifica as given by Utgaard and Perry (1964) was used for comparison with Dyer’s plesiotype of that species. The holotype of H. micro- stigma Cumings and Galloway, located in Indiana University, was studied in order to determine its relationship to H. robusta. The external features of the zoaria (i.e. shape of the colony, character of the surface) were observed with the aid of a hand lens, but the internal structures of each species were determined by means of thin sections. The mensuration of the number of zooecia in 2mm in the intermonticular areas and measurements in millimetres of the maximum dimension of zooecial apertures in the monticular and intermonticular areas were made with the aid of a binocular microscope and a micrometer scale calibrated to .01 mm. The number of entire mesopores and the number of entire acanthopores in 1 mm? were obtained by using a compound microscope and a reticle calibrated to 1 mm?. Statistical computations were made on the 1BM 370/165 computer at the University of Toronto Computer Centre. As most of the samples had heterogeneous variances it was not possible to test differ- ences among means using parametric statistical methods. Instead, the samples were tested for differences in dispersion using the non-parametric Mann-Whitney U-Test (Siegel, 1956). In the tables probability ranges associated with significance tests are designated with asterisks as follows: *** = P < 0.001; ** = P < 0.01; += P< 0.1; not-significant = ms*="P > 005: Systematic Palaeontology Order Trepostomata Ulrich 1882a, b Family Heterotrypidae Ulrich 1890 Genus Heterotrypa Nicholson 1879 Through a misidentification, originally detected by Ulrich (1882a), Nicholson (1879) designated a type species for Heterotrypa that did not fit the concept of the genus as utilized by Nicholson, Ulrich (1895) and all subsequent workers. Utgaard and Boardman (1965) reviewed the nomenclatorial problem of the type species of Heterotrypa and proposed to the International Commission on Zoological Nomen- clature that Monticulipora frondosa D’Orbigny, 1850 be designated the type species of the genus Heterotrypa. This proposal was approved and published as Opinion 838 (1968) of the International Commission on Zoological Nomenclature. Nicholson’s description of Heterotrypa (1881) is somewhat fuller than the original of 1879: “‘Corallites of two kinds, the larger ones subpolygonal, partially separated by the development of numerous smaller, circular or irregularly shaped tubes, of which there is no more than a single row between any pair of larger tubes. Walls thickened towards the mouths of the tubes, and often apparently amal- gamated in this region. Spiniform corallites usually present, but sometimes wanting. Tabulae conspicuously more numerous in the smaller tubes than in the larger ones.” Boardman and Utgaard (1966) presented the following emended definition of Heterotrypa: Zoaria are frondose, ramose, or less commonly incrusting. In exozone, individual zooecial walls can be extremely variable in thickness, and in some species are conspicuously moniliform. In longitudinal section, the zooecial boundary is commonly a conspicuous dark line in inner exozones and a broad zone of abutting laminae or completely obscured in outer exozones. In some earlier species of the genus, zooecial boundaries are narrow and well defined throughout exozones. Wall laminae are broadly convex on either side of the boundaries and lighter colored zooecial linings are common in thicker-walled specimens. Walls generally are amalgamate in appearance and mural lacunae are prominently developed in several species. Diaphragms are generally few in endozones, but are moderately abundant in some species. In exozones, diaphragms are commonly closely and regularly spaced, thin, planar and perpendicular to zooecial walls. Locally, diaphragms are widely or irregularly spaced, convex, or cystose. Intermonticular mesopores range from abundant and regularly arranged in some species to scattered or essentially absent in others. Mesopores commonly develop monili- form chambers at proximal ends and tend to become smaller or are terminated distally within exozones. Mesopore diaphragms commonly are noticeably thicker and more closely spaced than zooecial diaphragms. Mesopore walls are thinner and more irregular in thickness than zooecial walls. Acanthopores are of at least two kinds within the genus, regular acanthopores limited to exozones, and endacanthopores originating in both endozone and exozone. Exozonal acanthopores are present in most species, generally between zooecial corners, and either extend throughout the exozone or are shortened and restricted to a part of the exozone. The shortened acanthopores are commonly offset and occur in concentrated zones within a zoarium. The fully extended acanthopores can be either centered or offset. Endacanthopores originating in endozones occur in all species. Some endacanthopores originate in inner exozones also in most species. Both types extend into exozones and generally terminate within broader exozones so that shallow tangential sections show few if any endacanthopores. Some endacanthopores are oblique to the axis of zooecial voids in the exozone. Endacanthopores occur in zooecial corners and are typically centered in petaloid clusters of several zooecia. They are generally larger and never smaller in diameter than exozonal acanthopores. Monticules generally have a central cluster of a few to many mesopores surrounded by larger zooecia than those in intermonticular areas. Within monticules, acanthopores can be larger in diameter and walls thicker than those in intermonticular areas. Type Species Heterotrypa (Monticulipora) frondosa D’Orbigny 1849 A feature not often referred to in the study of trepostomes is the granular nature of the zooecial wall laminae. Cumings and Galloway (1915) using magnifications 287 demonstrated clearly that the concentric laminae comprising the walls revealed the presence of granules which varied in size according to their particular location. The granular nature of the wall is especially well shown in sections studied in this project (Figs. 4, 5). Using the scanning electron microscope (SEM) the morphology and possible function of these granules might be revealed. Heterotrypa definita Dyer, 1925 Figs. 1A-C, 5E-F Original Description (Dyer, 1925) The coarse branching zoaria of this well-defined species are found in great numbers in the bryozoan reef in the Strophomena varsensis zone of the Erindale member. The branches are large, commonly reaching 15 mm in diameter. Maculae, each made up of about 20 mesopores, are arranged evenly over the surface with an average distance of two millimetres between them. In tangential sections H. definita resembles H. simplex maculosa Dyer of the Streetsville member in that the acanthopores are arranged very similarly, one to each angle of junction of the zooecial walls. It differs, however, from that species in the distribution of mesopores. In H. definita they are gathered into maculae as well as being distributed evenly throughout the whole zoarium, while in H. simplex maculosa they are found only in the maculae. In addition, the groups of mesopores are never surrounded by zooecia of larger than average size in the former as they are in the latter. The most striking characteristic of this species is observed in the longitudinal sections. At different periods of growth of the zooecia the walls become so swollen that a long continuous line of swellings can be followed for the whole length of the section, in one instance for a distance of three millimetres. The diaphragms are comparatively numerous, an average of 10 being found in each tube, but they are entirely wanting in the axial zone. In the same manner as the swellings referred to above, the diaphragms occur at similar levels in the various zooecia, giving the appearance of continuous horizontal lines in the vertical section. In some cases the lines of diaphragms coincide with the lines of swelling, and in other cases they alternate with them. This species has been placed in the genus Heterotrypa on account of the numerous diaphragms, thick walls, and general resemblance to undoubted members of that genus from the Credit River Section. In one feature, however, it greatly resembles Stigmatella, namely, in the possession of periodic thickenings which is considered by Ulrich and Bassler as one of the characteristics of the latter genus. The coarse, branching surface covered with maculae, and the periodic thickening of the walls form a combination of features by which this form is easily distinguished from any other species of bryozoa. 4 wyryyyy UE, Fig. | A-c. Heterotrypa definita, Dyer, X30. A-B. Tangential sections (ROM 12154). ou Longitudinal section (Rom 12154). Emended Description Dyer based his description of the microstructure of H. definita upon sections from syntype ROM 12155, an embedded specimen which gave no clue to the shape of the zoarium. Syntype ROM 12154, a well-preserved specimen free from the matrix, revealed the zoarial form. This specimen is herein selected as a lectotype. Dyer assumed that this specimen belonged to the same species, although he made no sections to substantiate the assumption. However, from a study of sections now available it is clear that the two are conspecific. EXTERNAL FEATURES Zoarium of large, round to slightly compressed branches given off dichotomously (Dyer, 1925), diameter ranging from 13 to 20 mm; before bifurcation zoarial mass reaches width of 35 mm. Surface with small, inconspicuous monticules, 1.5 to 2 mm apart measuring from centre to centre, and composed of larger zooecia than in the intermonticular areas; centre of monticules with cluster of mesopores. TANGENTIAL SECTION Zooecial apertures angular in deep sections where wall thin, subangular to sub- circular to circular near surface where wall thickens (Fig. 1A, B), 7 to 12 entire zooecia in 2 mm (Table 1); thickness of zooecial walls ranges from 0.01 mm (or less) in deep parts of section to 0.03—0.05 mm in sections near surface, and up to 0.07 mm in monticules; wall concentrically laminated, laminae granular, at surface wall dense owing to closely packed laminae, in peripheral zone median light- coloured ring, at greater depth light-coloured ring replaced by faint black line of demarcation. Mesopores 5-6 in 1 mm? in intermonticular area (Table 1). Acantho- pores abundant, 25—43 in | mm? in intermonticular area (Table 1), seldom inflecting near surface but strongly inflecting in subsurface sections, diameter range 0.01 to 0.04 mm, commonly 0.03 to 0.04, situated usually at the angles of junction of adjacent zooecia and composed of dense concentric laminae with small central lumen. Monticules with larger zooecia than those in intermonticular areas and with clusters of small mesopores in centre, the clusters often exhibiting a stellate arrangement (Fig. 1A, B). Maximum diameter zooecial apertures in mm in mon- ticules 0.14-0.19 (Table 1). Maximum diameter of zooecial apertures in inter- monticular areas 0.09-0.13 mm (Table 1). LONGITUDINAL SECTION Zooecia curve broadly from axial to peripheral zone intersecting zoarial surface either at right angles or somewhat obliquely; several periods of growth represented (Fig. 1c). Walls very thin in axial zone with periodic fine crenulation, thickening greatly and becoming slightly moniliform from base of the peripheral zone; wall laminated, laminae convex outward, diverging from light-coloured central area usually at an angle of about 40-45° and passing into diaphragms. Diaphragms straight or slightly oblique, virtually absent in the thin-walled axial zone, their apparent absence possibly due to destruction, numerous throughout the peripheral zone where 10 to 12 occur in a given zooecium, spaced from one-half to two tube diameters apart, the broader spacing being in the subperipheral area. Sections passing through a monticule show clearly the central cluster of small mesopores with closely spaced diaphragms. Acanthopores flanked by laminae which extend outward and diverge from central light-coloured lumen at a relatively low angle then pass into zooecia and mesopores; acanthopores often cut across trend of zooecia. 6 SU O'ETT su OLY su 0'L8 su 0'9L su ¢°L8 onsneVg PQ) AouiYAA-uUPpy (070-10) 100°0+ 610 (97'0-SZ'0) 100°0+ $70 (9T-8) 970+ 0°9T (OI-S) €TOFOTT (OI-6) ‘A'S F uvayy DSOWDAGNS *H OI OT (7Z'0-r1'0) 700°0+ LI‘0 (67'0-61'0) 900°0+ 7720 (ZI-S) VG ik (07-0) EC LEGS (¢°6-6) ——— ‘A'S F uvayy vaiyfiyjoid * Oc 0c Oc Oc 0c vale Je;NdUOWII}UI UI BI9900Z JO JaJOWILIp JeInjiode WiNnUIxeyy S3[NIIJUOW UI P19900Z Jo JojoweIp yeinjiode wnurxeyy vale IV[NONUOU!II}UI UI ,WW | Ul SoIOdoyjULOR 911]Ud JO JoquINNy vole Iv[Nd}UOUWII}UI UI ,WUI | Ul SaIodosaw situa JO Jaquinyy vole IJE[NOYWUOWIIIUI UI WW Z Ul BID900Z JO JaqUINN ‘SoSsuvI 9JOUNP SaSoyJUIIVd UI SIINGIY ‘SIIJOWNIU Ul UDAIS 918 SJUDWOINSvITA, “(6L “d ‘PO6T ‘A1IIq puv plves}y WO usyv} VsOwDGns *}] 10J vyep MEY) °(291f/401d wWAUOUAS) DsOWDAGns *F] pue (9Z7ZZT WOU) VIYYO1d Ddfisyo1aja HY JO uostaedwoyd °Z aIquy xxx 00 + 00 xa 00 su QTL su ¢°98 onsneg Q AouzyM-uuepy (070-10) 100°0+ 610 (97'0-S7'0) 100°0+ $70 (91-8) 9r'0+0°9T (OI-S) ECOTOM (01-6) "Q'S F uray DSOWDAQGNS * Ol Ol (€1°0-60'0) c00'0+ T'0 (610-110) 700'0+ 02'0 (€p-S7Z) LOD aa ve (9-¢) 60°0+ 9°¢ (ZI-L) LOORCIO ‘aS F uray pyiuifap *H 0c Oc Oc 0c 0c Bale Ie[NSYUOWII}UI UI BIN900Z JO JO}AWIvIP [eINjJode WNWIxeyy S9]NoUOW UI BIN900Z JO JOJOWILIP JeINjJode WNWIxeyy Bale Iv]NOUOWII}UI UI ,WUI [ UI SalodoyyUKOR JINNUS JO JOQqUINN vale Je;NONUOWII}UI UI ,WWW | Ul SaJOdosau a11jUd JO JoquUINN, Bale Ie;NOUOUIIIyUI UI WU Z Ul BID800Z JO JaquINN ‘sosuvl 9}0UNP Sasoy}UIIVd UT SOINSIY] ‘SOIJOUN[IU UT UDAIS JIB SJUDWIINSBITA] '(6L “4 ‘p96, ‘ALIOg puv plees}Q WOIy Udyv) [291/04d WIAUOUAS] DSOWDAGNS “FT IOJ vJep MBY) “VIYYyOI1d “FF pue vpUyap vdh4yosajayy JO uostivdwoy ‘[ a[quyl Remarks In placing this species in the genus Heferotrypa, | agree with Dyer that the thick walls and numerous diaphragms in the peripheral zone warrant the generic designation. Utgaard and Perry (1964), without examining Dyer’s types, stated that H. subramosa from their Indiana-Ohio fauna, which they regard as a synonym for H. prolifica Ulrich, differs from H. definita ‘“‘as the latter species lacks larger zooecia in the monticules than in the intervening areas and lacks diaphragms in the axial region’. The present study has shown that diaphragms are not lacking in the axial region and that H. definita possesses larger zooecia in the monticules than in the intervening areas although they are smaller than in the specimens of the above authors. Furthermore, the striking central clusters of mesopores in H. definita, which are characteristically stellate in shape, are a distinctive feature not observed in Indiana specimens. The two species show significant quantitative differences in the number of acanthopores in 1 mm?, in the apertural diameter of zooecia in mm in the monticular area, and in the apertural diameter of zooecia in the intermonticular area (Table 1). My conclusion, therefore, is that H. definita and H. subramosa are significantly different. Among the associated Credit species, H. definita and H. robusta are stout, ramose forms that might be confused. See H. robusta below for description of differences. Locality Meaford Formation, Upper Ordovician, Mullet Creek, Credit River, Erindale, Ontario (ROM 12154); Section 10, West Side, Credit River, north of home of William Crozier (ROM 12155). Type Lectotype ROM 12154; paralectotype ROM 12155. Heterotrypa prolifica (Ulrich 1890) Figs. 2A-B, 5C Atactopora subramosa Ulrich, 1879 Heterotrypa prolifica Ulrich, 1890 Heterotrypa prolifica Dyer, 1925 Heterotrypa subramosa Utgaard & Perry, 1964 Dyer (1925) referred to this species as follows: ‘‘This species occurs in the bryozoan reef in the Strophomena varsensis zone of the Erindale member. It differs from the type species in a few minor details. The acanthopores in the Credit River forms are a little larger than in the type and show a slight variation in size. There is also a greater tendency toward the grouping of mesopores in the type species. In Ohio, according to Shideler, H. prolifica ranges from the Lower Arnheim to the Upper Whitewater and, accordingly, is of little use for purposes of exact correlation.” 8 te, Dy 1 YY) y Ge Ye % Birt ye a Zi Fig. 2 A-D, X30. A-B. Heterotrypa prolifica Ulrich. c-p. Heterotrypa simplex Dyer. A. Tangential section, ROM 12226. c. Tangential section, ROM 12159. 4 Be Longitudinal section, ROM 12226. pb. Longitudinal section, RoM 12159. Fig. 3 a-c. Heterotrypa robusta Dyer, 30. B. Tangential section, ROM 12156. A. Longitudinal section, ROM 12156. c. Tangential section, ROM 12157. Emended Description EXTERNAL FEATURES Zoarium frondescent to ramose, frondescent fragment measures 20 20 X 7 mm; only bases of branches preserved, diameter of largest branch 6 mm. Surface with prominent, low-rounded morticules 2 to 2.5mm apart measuring from centre to centre. Acanthopores protrude at surface, giving it a spiny appearance. The dis- tinctive monticulose surface distinguishes this species from any other Heterotrypa in the collection. TANGENTIAL SECTION In deep sections zooecial apertures angular to subangular, becoming subcircular to nearly circular near surface (Fig. 2A). Zooecial wall 0.01 to 0.02 mm thick in deep sections, average width towards surface 0.05 mm, but may reach 0.09 mm in monticules; number of zooecia in 2mm 9 to 9.5 (Table 2). Wall concentrically laminated, dark and thick at growing edge where laminae compact, below this zone prominent light-coloured ring present; at depth where wall thin, faint dark line of demarcation often visible, thin ring of light-coloured laminae lines zooecial cavity. Mesopores, generally triangular or quadrangular, in axial region commonly situated between adjacent zooecia, some mesopores pinch out or become smaller before reaching surface where zooecial apertures are more circular. 0-20 mesopores in | mm? in intermonticular area (Table 2). Acanthopores range in diameter from 0.01 to 0.1 mm, most fall within range 0.03 to 0.5 mm, number in 1 mm? in inter- monticular area 5 to 12 (Table 2). Monticules composed of larger zooecia than those in intermonticular area, and a few small, angular mesopores indiscriminately disposed, apertural diameter of zooecia in monticules 0.19 to 0.29 mm (Table 2), apertural diameter of zooecia in intermonticular area 0.14 to 0.22 mm (Table 2). LONGITUDINAL SECTION Zooecia curve broadly from axial zone to periphery intersecting zoarial surface at low oblique angle (Figs. 2B, 5c). Zooecial wall thin and straight in axial region, thickening progressively from base of peripheral zone to surface and becoming moderately moniliform, diaphragms often join wall where monilae thickest (Boardman, 1960). Wall dense at growing edge where laminae compact, below which, throughout mature zone, median light-coloured area; as wall becomes thin in axial zone faint dark line of demarcation visible. Wall laminae relatively coarse, alternating light and dark incolour, convex outward in peripheral region, diverging at a low angle from median light band and merging with the light-coloured, laminar lining of zooecial cavity to continue into diaphragms in zooecia and mesopores. Diaphragms straight in axial zone, one to two tube diameters apart; more closely spaced as growth proceeds, in peripheral zone some are less than one tube diameter apart, are straight, concave, oblique, or even cyst-like (Figs. 2B, 5c). Mesopores in peripheral zone often bead-like, with diaphragms closer than in zooecia. Acanthopores in peripheral zone with central lumen, on either side of which laminae diverge at moderate angle and pass into zooecia and mesopores. Acanthopores protrude beyond zoarial surface. Remarks It is clear that Dyer’s plesiotype is closely related to Atactopora subramosa Ulrich (1879), and to Heterotrypa prolifica Ulrich (1890). In their study of H. subramosa iy from Ohio and Indiana, Utgaard and Perry (1964) considered these two species as synonyms. It should be noted, however, that the zoarium of H. prolifica, as originally described, possessed low, rounded tuberosities (1.e. monticules), a charac- teristic feature of the Credit Valley type, while H. swbramosa, as originally described, lacked monticules. Utgaard and Perry (1964) made no point of this difference, although the specimens they described possessed monticules. Qualitatively the present taxon is similar to the fauna from Ohio and Indiana in external form and in all microscopic counts. When the Credit species is compared quantitatively with data available from Utgaard and Perry’s type, no significant difference is noted; therefore, from the available evidence I am of the opinion that Dyer’s plesiotype should be designated H. subramosa. Locality Meaford Formation, Erindale Member, Cooksville, Ontario. Type Plesiotype ROM 12226. Heterotrypa robusta Dyer, 1925 Figs. 3A-C, 4A-C Original Description (Dyer, 1925) In the Streetsville member, several specimens of a coarse, ramose, smooth-surfaced bryozoan were found, in which the zoarium varies from 12 to 15 mm in diameter. In tangential sections, the outstanding features of the species are the strong inflection of walls by the acanthopores and the fact that most of these acanthopores are found between the angles of junction of the zooecial walls. They are fairly numerous and of medium size. The zooecial tubes are small, 11 being found in a space of two millimetres. The mesopores are not numerous and are usually distributed evenly throughout the zoarium but are occasionally gathered into maculae. In some parts of the tangential sections, distinct dark boundaries are seen between the adjacent zooecial walls, while in other parts of the same sections no evidence of a separa- tion is visible, the walls being completely fused. Less diversity is seen in the immature region where the walls are usually separate. The variability in this respect leads to the conclusion that the fusion of the walls is not a specific feature. A similar conclusion was reached with regard to other species. In view of these observations the writer is inclined to question the value of subdividing the trepostomatous bryozoans into Infegrata and Amalgamata. In longitudinal sections the axial portion is seen to be comparatively small, with a diameter not more than one-half that of the whole zoarium. In this axial part the tubes run upward and outward with very thin and crenulated walls. There are no diaphragms. On reaching the mature zone, the tubes turn abruptly and run directly to the surface of the zoarium at the same time becoming thick-walled. In this zone the walls are even and straight with a slight suggestion of periodic thickening. Diaphragms are present with a distance equalling one tube diameter between them. Mesopores and acanthopores are seldom seen in longitudinal sections. Emended Description EXTERNAL FEATURES Zoarium of stout, slightly compressed branches, maximum diameter 18 & 25 mm, surface with small monticules occurring at regular intervals of 2 to 2.5 mm, meas- IZ ured from centre to centre. Prominent, small rounded elevations of various sizes, representing aborted branches and best shown on syntypes 12157, 12158, give the surface a knobby appearance. TANGENTIAL SECTION Dyer’s sections are poor; new sections prepared for this study have furnished detail hitherto unrecognized. Zooecial apertures near surface subangular to circu- lar, walls thick, moderately inflected by acanthopores (Figs. 3c, 4c); walls in deeper sections somewhat thinner, zooecial apertures petaloid owing to pro- nounced inflection of acanthopores (Figs. 3B, 4B); in thinner-walled axial zone acanthopores only slightly inflecting, confined to angles of junction of zooecia. Zooecia 10 to 11.5 in 2 mm (Table 3), walls 0.01 to 0.02 mm thick in axial zone, 0.04 to 0.07 mm thick in mature zone to 0.09 mm thick in monticules; wall con- centrically laminated, dense at surface because of closely packed laminae below surface wall with median light-coloured ring; in axial zone, where wall thinnest, faint dark line of demarcation present. Mesopores mostly subcircular, few and small in intermonticular areas, number in 1 mm? in intermonticular area 1 to 4 (Table 3). Acanthopores abundant, 42 to 58 in 1 mm? in intermonticular area (Table 3), diameter 0.02 to 0.07 mm, small central lumen surrounded by concentric laminae. Zooecia on periphery of monticules larger than those in intermonticular areas, centres of monticules with groups of relatively large mesopores. Maximum apertural diameter in mm of zooecia in monticules 0.14-0.20 (Table 3). Maximum apertural diameter in mm of zooecia in intermonticular area 0.10-0.16 (Table 3). LONGITUDINAL SECTION Zooecia usually curve out broadly from base, in late axial region turn abruptly to intersect zoarial surface nearly at right angles (Fig. 3A). However, where an over- growth occurs initial zooecia subprostrate for short distance, then straighten and continue to surface where they open approximately at right angles (Fig. 34). Zooecial walls thin, straight, or sinuous in axial zone with periodic fine crenulation, at wide intervals a solitary monila occurs at same level across section; walls throughout the long peripheral zone becoming moniliform; wall laminae in latter zone alternating light and dark in colour, light colour believed due to presence of very fine granules; laminae convex outward, diverging at moderate angle of between 30 and 40° from light-coloured median area; at depth where wall thinnest median light area replaced by faint dark line of demarcation. Diaphragms few in axial zone, one or two in sub-peripheral zone, numerous in peripheral zone, straight to concave, spaced usually one to two zooecial diameters apart; where diaphragms located adjacent to wall monilae (Boardman, 1960), i.e. usually where monilae thickest, monilar laminae show most clearly passage into diaphragms. Mesopores rarely detected except where section cuts a monticule, in which case several adjacent mesopores occur each with diaphragms spaced apart one or two tube diameters. Acanthopores best observed in mature zone where the small central lumen is flanked by laminae which diverge outward at a moderate angle and pass into the zooecia and mesopores. Remarks Dyer stated that H. robusta resembled H. microstigma Cumings and Galloway (1913) more closely than any other species. I have examined the holotype of Hf. microstigma, 104646, 9122-22,23 from Waynesville (Lower Richmond) in Cut 13 I3 ee (€1'0-60'0) (910-010) vale Je[NIUOWIIU! su ¢9O¢T 7000+ 10 0c ¢00'0+ 10 07 UI BID9900Z JO JaJOWeIp [eInjJode UMNUWIxep] (61'0-VI'0) (0Z'0-VI'0) sajnonuow Ul su ¢°861 700°0+ C0 OC ¢b00'0+ 70 0Z BIN900Z JO JOJOWeIp jeinjiade wUNUWIxeyy (€p-SZ) (8¢-Zr) vale IeyNONUOUWIII}UI axa OV LOW eve 07 007 I + 8°8r 02 UI ,UILU [| Ul SaIodoyjUKoR oINUA Jo JaquUINN (9-¢) (p-T) BOIv Ie]NSTYUOUIIUI xx «x OO 600+ 17'S 0c 0970+ 17 07 UI ,WIUW | UI SaIodoOsauw 334U9d JO JaquUINN (ap) (C'IT-O1) vaIe Ie]NdYUOWII}UI aa SEL LOO CG 07 ScLO+S OL 07 UI WU Z Ul BID800Z JO JaquUINN onsne1g Q Aouyry A-uUReypy “TSF uvay u "TS F uray uU ojluyfap *H DISNGOA “HT S—_—aerrrrrr ‘Sasuvl 9}OUNp SasayjUoIEd UT SAINI] “SA1OUNT|[W UT UdATS 918 SJUdWAINSvayA] ‘V}UYap “FT pue vjsNqGo4 Ddfisjo1aja zy YO uostaedwoD “p ajquy, oo (81°O-Z1'0) (910-010) vale IE|NOTYUOWII}UI su ¢°89] €00°0+ rI'0 OC £00'0+ TO 07 UI BID90OZ JO JO}9WIIP [eINjJade wWinwuIxeyy (ZZ'0-0Z'0) (07'0-V1'0) sajnonuoU UI xxx S°C c00'0+ 70 07 7000+ 70 07 BI9900Z JO JOJOWIIP [einjJode wnwixepy (99-65) (8¢-@r) Bore Ie[NIUOUAUI +e 00 €0S'O+F L'19 Oc 007 1+ 8°8P 07 ul ,WUWI | Ul SoJOdoyjUROR aINUD JO JoquINN (Z-0) (p-1) Bae Ie[NIUOWIIIUI xx« O'6E CElTO+S0 07 097 OFZ 07 ul ,WUW | Ul SaJodosaw aiUd JO JoquUINN (OI-8) (ST 1-O0D) baie Ie[NOUOWIIIUI x OLE 1I9T'0+0°6 OC SCL OFS OI 0 Ur WU ¢ Ul B19900Z JO JIqUINN onsneig ¢Q Aouiiy A-uuepy “A'S F uvapy u ‘TSF urapy u DUISIJSOADIU * FY] DISNGOd *H sss ‘saduvs a}OUNp SosoyjUudIUd UT SIINBIL] ‘SOOUT|[IW UL UDATS JI SpUDWOINSKIA, “PUFIZSO4OIW “FT pue DjSNgos DdfisjosajzaTY JO uostavdwoy “¢ 91qe]. 14 on the Big Four Railroad near Weisburg, Indiana, which was kindly lent to me by the late Professor T.G. Perry of Indiana University. The Waynesville Formation is not now recognized by the Indiana Geological Survey, and the entire Maysville and Lower Richmond up to the Saluda Limestone is included in the Dillsboro Formation. Externally the zoarium of this type does not exceed 7 or 8 X 11 mm in diameter as compared with 18 & 25 mm in H. robusta. Qualitatively zooecia in H. robusta are smaller, mesopores more numerous, and acanthopores fewer than in H. microstigma. Quantitatively the two species differ significantly in number of zooecia in 2 mm in intermonticular area, number of entire mesopores in 1 mm? in intermonticular area, number of entire acanthopores in 1 mm? in intermonticular area, and in the maximum apertural diameter of zooecia in monticules (Table 3). I believe the two species to be distinctly different. H. robusta and H. definita are similar in the shape of the zoarium, but the knobby surface of the former is lacking in the latter. However, they differ in microscopic detail. In H. robusta the centres of the monticules are composed of relatively large and small mesopores whereas in H. definita the centres of the monticules have conspicuous clusters of numerous small mesopores of character- istic stellate shape, mesopores in the intermonticular space are fewer, and acantho- pores are more numerous in H. robusta than in H. definita. The two species com- pared quantitatively (Table 4) show that significant differences occur in the number of zooecia in 2mm in the intermonticular area, in the number of mesopores in 1 mm? and in the number of acanthopores in 1 mm? in the intermonticular area. They therefore represent separate species. Locality Meaford Formation, Upper Ordovician, Credit River, Streetsville, Ontario. Type Syntypes ROM 12156, ROM 12157, ROM 12158. Heterotrypa simplex Dyer, 1925 Figs. 2C-D, 5D Dyer’s Description (1925) This species is rather common in the Streetsville member where it forms ramose or sub- ramose, smooth-surfaced zoaria, with an average diameter of 10 mm, as in H. simplex maculosa (Plate vil, Figure 10). In tangential sections, it is seen that the tubes are of a very uniform size and rather small, twelve being found on the average in a distance of two millimetres. Mesopores are entirely absent. Acanthopores are numerous, comparatively small, and the regularity of their distribution is remarkable, one being found at each angle of junction of the zooecial wall. Very rarely is a departure from this occurrence found. In vertical sections, Heterotrypa simplex is almost identical with H. robusta (Plate u, Figure 7). The structure is so similar, as thus revealed, that a repetition of the description is unnecessary. In internal characters, Heterotrypa simplex resembles H. solitaria, Ulrich, of the Fairmount, but this species is frondescent rather than ramose in its manner of growth. From all other species of Bryozoa occurring in the Credit River Section, the present species may be distinguished by the very regular arrangement of the acanthopores and the entire absence of mesopores. 1) Emended Description EXTERNAL FEATURES Known only from a small fragment consisting of round to flattened branches 8 to 10 mm in diameter, surface with small, slightly elevated monticules, 1-13 to 2 mm apart, measuring from centre to centre, composed of zooecia larger than in inter- monticular areas and a few relatively large mesopores; acanthopores numerous and prominent. TANGENTIAL SECTION Zooecial apertures angular to subcircular and thick-walled at surface becoming angular and progressively thinner-walled at depth (Figs. 2c, 5p), 11 to 12 commonly in 2mm (Table 5), walls 0.01 to 0.02 mm thick in deep sections, 0.03 to 0.05 mm thick near surface, maximum 0.07 mm in monticules; wall concentrically laminated, dense at surface where laminae compact, below which, in peripheral zone, laminae display light-coloured ring; at greater depth where wall thinnest, laminae obscure, faint dark line of demarcation present. Mesopores few in intermonticular area (Figs. 2c, 5p), number in 1 mm? 0 to 3 (Table 5). Acanthopores numerous, 28 to 46 in | mm? in intermonticular area (Table 5), situated in the zooecial angles, never inflecting, 0.01 to 0.04 mm in diameter, normally 0.03 mm, composed of laminae Surrounding a small central lumen. Monticules with larger zooecia and with thicker walls than in intermonticular areas and with very few mesopores not in clusters (Figs. 2c, 5p), maximum apertural diameter of zooecia in mm in monticu- lar area 0.14 to 0.22 (Table 5); maximum apertural diameter of zooecia in inter- monticular area 0.09 to 0.13 (Table 5). LONGITUDINAL SECTION Zooecia swing outward in a broad curve to open at approximately right angles on reaching surface (Fig. 2D); walls thin in axial zone, straight to finely crenulate, thicken gradually from outer axial and inner sub-peripheral zones, becoming relatively thick, in places moniliform in moderately long peripheral zone; wall concentrically laminated, laminae best seen in peripheral zone, convex outward, diverging at an angle of 35° to 40° from a median light-coloured area (lumen) then passing into diaphragms. Laminae granulose, alternating light and dark, light laminae possibly more finely granulose. Diaphragms in the outer axial zone where one or two occur, thereafter diaphragms mostly straight, numerous, com- monly 3 to | tube diameter apart (Fig. 2p). Acanthopores best observed in peripheral zone where they at times cut across the trend of a zooecium, consist of a light-coloured, central lumen, from which laminae diverge at a moderately low angle and pass into diaphragms in zooecia or mesopores. Remarks Dyer stated that H. simplex resembled H. solitaria Ulrich (1883). I have not had access to Ulrich’s holotype (USNM 43664) but after carefully reading his description and examining his figures | have come to the conclusion that the two species have little in common. The closest relationship between H. simplex and the present fauna is with H. robusta and H. definita. The one small fragment of the type of H. simplex which exists has the knobby surface of H. robusta. Also, when the two are compared qualitatively they differ in microscopic detail, namely, number of zooecia in 2 mm in intermonticular area, 16 iY, 7. S Fig. 4 a-c. Heterotrypa robusta Dyer, X60. B. Deep tangential section, Rom 12156. A. Longitudinal section, Rom 12156. C. Tangential near surface, Rom 12157. number of entire mesopores in | mm? in intermonticular area, number of entire acanthopores in 1 mm? in intermonticular area, maximum apertural diameter of zooecia in monticules, and maximum apertural diameter of zooecia in monticules, and maximum apertural diameter of zooecia in intermonticular area (Table 5). Compared quantitatively, the two differ significantly in the number of zooecia in 2mm in intermonticular area, number of entire mesopores in | mm? in inter- monticular area, number of acanthopores in 1 mm? in intermonticular area, and in the apertural diameter of zooecia in mm in the intermonticular area (Table 5). H. simplex and H. definita are similar in zoarial shape but the latter lacks the knobby surface; furthermore, the monticules in H. simplex lack the central, stellate clusters of small mesopores characteristic of H. definita. In H. simplex the number of zooecia in 2 mm in the intermonticular area is 11 to 12, compared with 7 to 12 in H. definita (Table 6), and fewer mesopores occur in | mm? in H. simplex. When compared quantitatively, the two species show significant differences in the number of zooecia in 2 mm (Table 6) and in the number of entire mesopores in 1 mm? (Table 6). Locality Meaford Formation, Streetsville, Ontario. Type Holotype RoM 12159. Heterotrypa simplex maculosa var.noy., Dyer, 1925 Figs. 54-B, 6A-B Original Description (Dyer, 1925) The above variety differs from Heterotrypa simplex only in the occurrence of maculae. These are placed at wide irregular intervals over the surface of the zoarium and are not raised above the general level of the zoarial surface. They are composed of mesopores, five to twenty in number, and in certain places are surrounded by zooecia larger than the average. In both Heterotrypa simplex and H. simplex maculosa, quite definite boundaries be- tween the zooecia are seen in sub-mature regions, but, as in Heterotrypa robusta, the walls become fused in the mature regions. The variety occurs in the Streetsville member, very often in association with Heterotrypa simplex. Emended Description EXTERNAL FEATURES Zoarium ramose, round branches with diameter 10 mm, flattened branches 7 by 15 mm. Surface with small, closely spaced, slightly elevated monticules (maculae of Dyer) averaging 1.5 mm apart, measuring centre to centre, centres composed of groups of mesopores surrounded by larger zooecia. TANGENTIAL SECTION Zooecial apertures angular at depth, subangular to subcircular, nearly circular where wall thickest at zoarial surface (Fig. 6A), generally 10.5 to 12 in 2mm 18 (Table 7). Zooecial walls 0.01 mm (or less) thick in deep parts of section, typically 0.02 to 0.03 mm thick in sections near surface, and as much as 0.07 mm thick in monticules; wall concentrically laminated with light-coloured median ring in peripheral region, faint dark line of demarcation in axial region. Mesopores almost absent inintermonticular areas (Table 7). Acanthopores numerous, situated in the zooecial angles and not inflecting the apertures (Table 7), fairly uniform in size, diameter commonly 0.02 to 0.03 mm, composed of laminae surrounding a small central lumen. Monticules with central clusters of small mesopores, numbering as many as 25 in a cluster, and surrounded by zooecia larger than those in the inter- monticular areas (Fig. 6A). In monticules diameter (mm) of zooecial apertures in 1mm? 0.15 to 0.23 (Table 7); in intermonticular area diameter of zooecia in 1 mm? 0.09 to 0.13 (Table 7). LONGITUDINAL SECTION Zooecia curve broadly (locally sharply) from axial into peripheral zone then continue in a straight course to intersect zoarial surface at right angles or nearly so (Fig. 6B); walls straight, wavy, occasionally finely crenulate in axial portion, gradually thickening in outer axial region, thickening appreciably and becoming periodically moniliform throughout passage of relatively long peripheral zone; wall laminated, laminae convex outward and diverging at a low angle and passing into the diaphragms; diaphragms appear in outer axial region, becoming more numerous in peripheral zone where they are spaced from 3 to 2 tube diameters apart. Acanthopores, prominent in peripheral zone, appear to be a facsimile of their counterpart in Heterotrypa simplex. Sections cutting through a monticule show central cluster of small mesopores with closely set diaphragms, the cluster bounded by larger zooecia. Remarks The presence of clusters of small mesopores comprising the centres of the mon- ticules (maculae of Dyer) distinguish this subspecies from H. simplex; otherwise the two are very similar when compared qualitatively. Quantitatively significant differences occur in the number of entire acanthopores in 1 mm? in the inter monticular area (Table 7), and in the mm measurements of maximum apertural diameter of zooecia_in the monticules (Table 7). The only other associated taxa, having clustered mesopores, with which H. simplex maculosa might be confused is H. definita. In the former the clusters of mesopores are solid (or nearly so), in the latter they are more loosely assembled, characteristically stellate in shape. Compared quantitatively the two differ significantly in all computed measurements (Table 8). H. simplex maculosa is herein considered to be the species, H. maculosa. Locality Meaford Formation, Streetsville, Credit River, Ontario. Type Syntypes ROM 12160, 12175. 19 Heterotrypa meafordensis Fritz, 1974 (New Status) (Heterotrypa subpulchella paryvulipora Dyer, 1925, var. nov.) Fig. 6C-D Dyer’s Original Description (1925) Among the older collections of Bryozoa from Streetsville in the Royal Ontario Museum of Palaeontology, one specimen was found which closely resembles Heterotrypa sub- pulchella (Nicholson), of the Maysville of Ohio. In form it is a flattened sub-ramose mass, measuring 32 mm in length, 20 mm in width, and 13 mm in height. It probably branched, since the broken bases of branches are still seen. Maculae are scattered over the surface of the zoarium, with an average distance of one millimetre between them. They are scarcely raised above the general surface of the zoarium. The variety resembles the type in tangential sections, particularly in the character of the maculae, which consist of mesopores to the number of 10 or 15 in each, surrounded by zooecial tubes of distinctly larger than average size. The acanthopores are numerous and vary considerably in size, some of them being abnormally large. They are usually found between the angles of junction of the zooecial walls. The zooecia of the new variety are smaller than in the type of the species, 11 to 12 being found in two millimetres, in the former; while in the latter, no specimens have been recorded in which they are more numerous than nine in two millimetres, and according to Nicholson there are only six to seven tubes in this distance. This is the most outstanding difference between the two forms. Another difference is that in H. subpulchella parvulipora, the mesopores are confined to the maculae, while in Nicholson’s species they are sometimes found between the maculae. The two forms are very similar in vertical sections. They possess thin, crenulated walls, with the average number of diaphragms for the genus to which they are referred. Even here, however, there is a different, H. subpulchella having more diaphragms in the axial region than H. subpulchella parvulipora. Emended Description EXTERNAL FEATURES -Zoarium fragmentary, composed of branches given off irregularly, largest of which is 10 mm in diameter; surface with randomly disposed, mamelon-like elevations 1 mm in height, diameter at base 2 to 4mm, suggesting aborted branches; small flat-topped monticules approximately 2 to 2.5mm apart occur. Pyritization has obliterated the microstructure except in certain areas. TANGENTIAL SECTION Zooecial apertures subangular to nearly circular in sections near surface, angular and with thinner walls at depth (Fig. 6D); 11 to 11.5 commonly in 2 mm (Table 9), zooecial walls 0.01 to 0.02 mm thick in deep sections, 0.02 to 0.06 mm near surface and up to 0.09 mm thick in monticules; wall concentrically laminated, individual Fig. 5 a-F, X60. A-B. Heterotrypa simplex maculosa Dyer. Longitudinal section, RoM 12175. B. Tangential section, ROM 12175. c. Heterotrypa prolifica Ulrich Longitudinal section, ROM 12226. D. Heterotrypa simplex Dyer Tangential section, ROM 12159. E-F. Heterotrypa definita Dyer. E. Longitudinal section, Rom 12154. F Tangential section, ROM 12154. ‘a 20 i pe MMP Qi" UW. %G WM tits laminae with granules very clearly visible at growing edge, below which median light-coloured ring present, replaced at depth by thin dark line of demarcation. Number of mesopores in intermonticular area | to 6 (Table 9). Acanthopores situated in zooecial angles, seldom inflecting, commonly | to 3 where three zooecia are in conjunction, composed of concentric laminae surrounding a central lumen, diameter 0.02 to 0.06 mm, | to 4 in 1 mm? (Table 9). Monticules with central clusters of mesopores, surrounded by zooecia larger and with thicker walls than those in intermonticular area. In monticules diameter of zooecia in mm 0.18 to 0.24 (Table 9). In intermonticular area diameter of zooecia in mm 0.10 to 0.14 (Table 9). LONGITUDINAL SECTION Zooecia curve broadly outward to open at surface nearly at right angles (Fig. 6c); wall thin, straight or coarsely crenulated in axial zone, thickening gradually from the outer axial zone and early peripheral zone, becoming relatively thick and moniliform throughout remainder of peripheral zone (Fig. 6C); walls concentrically laminated, individual laminae clearly defined, dark in colour alternating with clear areas where laminae are more finely granulose. Laminae convex outward diverging from central area at relatively low angle and passing into diaphragms. Diaphragms absent in early axial zone, | or 2 present in passage to peripheral zone, becoming numerous thereafter and spaced from 4 to 2 tube diameters apart. Acanthopores in peripheral zone show convex laminae diverging from comparatively large lumen at moderately low angle to continue into zooecia and diaphragms. Remarks This variety is not to be confused with Heterotrypa parvulipora Ulrich and Bassler (1904), the type specimen of which comes from the Catheys Limestone of the Trenton, along Love Branch of Catheys Creek in Maury County, Tennessee. | disagree with Dyer in his associating the “variety” with H. subpulchella Nicholson (1875): for one reason the zoarium of H. subpulchella consists of “‘ramose com- pressed branches which may be quite frondescent and are partially hollow cen- trally.”” Furthermore, in the matter of internal structure the most striking difference lies in the non-crenulate, non-moniliform character of the zooecial walls in H. subpulchella, an obvious feature of Dyer’s “variety”. Of the associated fauna, H. meafordensis and H. robusta are alike in shape and knobby surface, but in thin sections the zooecial walls of the present form are coarsely crenulated with occa- sional prominent monilae. The monticular pattern resembles that of H. definita in that the central clusters of mesopores are somewhat stellate in shape, but differs from it in the knobby surface of the zoarium. Fig. 6 a-D, 30. A-B. Heterotrypa simplex maculosa Dyer. A. Tangential section, RoM 12175. B. Longitudinal section, rom 12175. c-D. Heterotrypa meafordensis, Fritz. c. Longitudinal section, rom 12161. D. Tangential section, Rom 12161. 22 j “., Wy 23 All three species referred to in the foregoing remarks are compared quantitatively in pairs in Table 9, where A represents H. meafordensis, B H. robusta, and C H. definita. Resulting analysis shows: A and B differ significantly in number of zooecia in 2 mm in intermonticular area, in number of entire mesopores in 1 mm? in intermonticular area, in number of acanthopores in | mm? in intermonticular area, and in maximum diameter of zooecia in monticules. A and C differ significantly in number of zooecia in 2 mm in intermonticular area, in number of entire mesopores in 1 mm? in intermonticular area, in number of acanthopores in 1 mm? in intermonticular area, and in apertural diameter of zooecia in mm in monticules. B and C differ significantly in number of zooecia in 2 mm in inter- monticular area, in number of entire mesopores in | mm? in intermonticular area, and in number of entire acanthopores in 1 mm? in intermonticular area (Table 9). From materials available for study it is concluded that Dyer’s variety represents a distinct species for which I suggest the new name Heterotrypa meafordensis on the grounds that, as shown, the term “‘parvulipora” is preoccupied. Locality Meaford Formation, Streetsville, Ontario. Type Holotype ROM 12161. 24 So rrr (€1°0-60'0) su Q'I9T 7000+ I'0 OC (61'0-rI'0) SU C’6ET 7000+ 70 Oc (€b-SZ) SU O'I9T LOTHE'VE 0Y6 (9-¢) xxx 00 600+ 7's OC ied) xx O'8C LTO+76 OC onsneig ¢ Aouiry -uueyy “A'S F uray u puafop “H (€1'0-60'0) €00°'0+ 1'0 (ZZ'0-v1'0) 600';0 +70 (9b-87) OIF Le (¢-0) STO+0' (ih) 600F 1 IT ‘A'S F ueayy xajduis "YY 0c 0c Oc 0c 0c vale Je]NUOUIIIIUI UI BIDJ0OZ JO Ja}OWIpP [eInjjode wWnuIxey Sa[NdyUOW UI BI9900Z JO JoJOWeIpP [eInjode wnwIxeyy BOIe IV[NOVUOWII}UI Ul ,WU | Ul SarodoyjUROR aINUS JO JaquINN Roe IL[NYUOWII}UI UI ;WW [ Ul SaJOdosou aiNUd JO JaquINN vole Ie[NOUOWII}UI UI WW Z Ul BID900Z Jo JaquINN nn nn ‘sasuvl oJ0Uap SasayjUaIEd UT SIINSIY ‘SAIVOU|[IW Ul UDATS 91 SJUDWIOINSvayA] ‘DZ2UYap * FT pu xajduius pdfisjo1aja 7 JO uostiedwiod “9 aIqQu]. eer =O (910-010) xOTTT ¢00'0+ T'0 OC (0Z'0-vT'0) su C/E] p00'0+70 OC (8S-Zr) xxx OT O07 1+ 8°8Pr 0c (p-T) xx O76 0970+ I'C OC (I I-01) xxx O'19 CCL OFS OL OC onsneis 9 Aouyry-uuepy “T'S F uvopy u DISNGOA “FT Boe IB]NII}UOUWII}UI so]NoNUOU Ul Bole JV[NOYUOWII}UI vole Te[NOVUOWI9}UI vole IB[NOYUOUWII}UI (€1°0-60'0) €00'0+ 10 07 UI BID900Z JO JOJOWeIP |vInjJade wWNuIxeyy (7Z°0-V1'0) ¢00';0+ 70 07 BIN900Z JO JaJOWIP [eInjJode WnwWIxepy (9-87) OLLIE Le OZ UI ;WU | Ul Sarodoy}URoR INU Jo JaqUNN (€-0) STO+OT 07 UI ,WU | Ul SaJOdosawi a11}Ua JO JaquINN Gay 600+ tr TT 07 UI WU Z Ul vID900Z JO JaquInNy "T'S F uvopy u xajduis * ir ‘sasuvl 9j0Uap Sasayjuoted UT SOINSI] “SOIJIW||IUL UT UDAIS 91v SJUWOIMSKIA] ‘DISNgod “FT pue xa;dwis vdfisjosaja Fy JO uostivduloy ‘s aque 25 (€1°0-60'0) # SETI 700'0+ T'0 (61'0-¥1'0) xxx O'9 t00'0+ 7'0 (€p-SZ) xa O'LO LOVEE (9-S) + OO 600+ F's (ZI-L) xa O8E LOOT C6 onsneig Q Aauiiy A\-uueypy "TSF uray] piuyop *H 0c Oc Oc Oc Oc (€1'0-60'0) Z00'0F 10 (€Z°0-ST'0) S00';0+Z'0 (8t-ZE) LULE8 tr (b-0) 8ST OFr'I (ZI-S'O1) OVOFITII ‘ASF uvaypy psojnovul Xajduiis * FY 0c Oc 0c OC Oc bole Iev[NOYUOUWI9}UI UI BIN900Z JO Jo}IUIBIpP jeinjiade WINUWTXe J] Sa[NoUOW UT BI9900Z JO JQ}9UvIP [eINjJode wiNUWIxepy vale Ie[NIYUOWII}UI Ul ;WW | Ul saJodoyjURoR dIUAa JO JaquINN vale IE;NOUOWIIIUI UI ,WWW | Ul SaJOdosaw aU JO JAaqUINN BaIB IJE[NOYUOWIIIUI Ul WU Z Ul BIDB00Z JO JAqUINN ‘sasuvl ajJousp SasayjuaIEd UI SAINSI,] ‘SOIJOUN[TW UT UdAIS 31v SJUDWIOINSKATA, “Y7ZUIfap *FY puv vsopnovu xaj;duus vdfisjo1aja FY JO uostavdwioy *g a1quy (€1°0-60'0) su O'PST £00°0+ 10 (ZZ'0-11'0) + OSTI c00'0+7'0 (9-87) +a SC8 OVI+P Le (€-0) su go] S7O+FO0'T (i=t) su Q’LST 600+ PIT onsneig Q Aouiry A-uueyy “A'S F uvapy xajduis *}] Oc OC Oc (€1°0-60'0) c00'0+ 10 (€Z°0-ST'0) c00'0+ 70 (8t-7E) LOVTtS CV (p-0) 8c 0+ 7'I (ZI-S'O1) OVO+T II “A'S + UvI|l Oc Oc 0c psojnovul Xajduas * HY vale Ie]NOUOWIIVUI UI BID3900Z JO JO}OWIVIP JvINyJode WiNnUIxe sa[nouOW Ul B19900Z JO Jo}OWvIP JeIN}Jode WNWIxeyA] vaIv Ie]NOUOUWII}UI ul ,WWW | Ul SaJOdoyjULOR aINUD JO JaquINN BIIV IE|NOUOWIIU! UI ;WW | Ul SaJodosaw aiNUa JO JaqUINN BIIV JETNSUOWIIIUI UI WW Z Ul BIDI00Z JO JAQqUINN ‘SosuBI 9J0UIP SasoyjUdIVd UT SIINSIY ‘SIIJIWAT][[TW UT UDAIS J1v SJUDWIINSKIyA] “Xa/duus “FY pue vsopnovwu xajduus pdfisjo1aja 7 JO uostvdwoy “Lf Iquye 26 su COT OYE SU CPP] OVV (€T°0-60'0) (910-010) (v1'0-O1'0) SUQ'LOT GOV 700'0+ T'0 OC ¢00'0+ T'0 Oc €00'0+ 10 SU C’861 OE xxx O0€ O8V (61'0-VI'0) (070-10) (bZ'0-8T'0) xxa OSC GPV 700'0+ 70 OC 7000+ 70 Oc €00'0+7'0 xxx OD OPE x*x00 OF8V (€p-SZ) (8S-Zh) (p-T) x*% 00 GeV LO THEE OC OC 1+ 8°87 OC CCOTS ZT xxx 00 O74 xx&a O19 OVV (9-¢) (p-1) (9-1) x* O10] GV 600+F1'S OC 097 OF TZ Oc O8EOFS'E xxx CEL OV xxx OTE OPV (ZI-L) (CII-OD) (IS) xxx 669 GeV LTO+7 6 OC C7LO+S OF Oc LSOO+C TT osneis 9 AouiyA-uuey “A'S F uray u “T'S F uray u “aS F uray puuyap H+ vIsngol"H sisuapiofoau "HE W 0c Oc 0c Oc OC BOIL IV|NUOWIIJUI UI BIDI0OZ Jo Ja}OWIpP jeInjsode winwIxep Sa[NONUOUI UI PIDa00Z Jo JoJoWIVIp [einjiode WiNnWIxeyy BOIV IL[NIUOWAII}UT UI ;WU | ul soIOdoyjULdR d1]Ud JO JAQUINN vole IV]NOYUOWII}UI UI ;,WU | UI SoJOdOsaWI a11Ua JO JaquINN BIIV IV|NOUOUWII}UI UI wu Z UI vI9300Z Jo JaquinN eee eee eee ee er LLL ‘Sasuvl djJOUNp SdSayjUsIEd UI SIINSI,] ‘SOIJOW|[TU Ul UdAIS 91v SJUDWIANSvIy\] “YZUIfap ‘FH pue vysnqo. * PY ‘sisuapsofoaw vdfisjo1aja yz] JO uostswdwior) *6 3/quL 27 Conclusions The striking similarity of the taxa described in this paper affords evidence that the assemblage represents an evolving population in which closely related forms were subjected to successive pressures resulting in minor changes in the skeletal struc- tures. In modern taxonomy they might possibly be regarded as subspecies. Herein, however, they are considered to represent separate species. Heterotrypa simplex maculosa becomes Heterotrypa maculosa and Heterotrypa subpulchella parvulipora is given the new name Heterotrypa meafordensis. In ROM’s Department of Invertebrate Palaeontology, the remaining treposto- matous bryozoan types from the Toronto region belong to the Family Monticu- liporidae. Study of remaining types is now in progress. Ultimately I propose to publish separately a table to include data on all the redescribed types in the ROM such as Tables 6 and 7 by Corneliussen and Perry (1973), in which the authors coded the observable characters within a species as present or absent. Several advantages accrue from tables of this sort: e.g., they indicate what characters were sought and this is important in that ideas concerning the taxonomic value of given characters change from time to time. Furthermore, now that numerical taxonomic techniques are commonly employed, the included raw data may serve a useful purpose in future studies. Acknowledgments To Dr. Allan Baker, Assistant Curator, Department of Ornithology, Royal Ontario Museum, I am indebted for his generous assistance in calculating the Mann-Whitney U-tests. The late Professor T.G. Perry, Indiana University, lent the holotype of Hetero- trypa microstigma Cumings and Galloway, IU 4646, 9122-22,23 from the Waynes- ville (Lower Richmond), Cut 13 on the Big Four Railroad, near Weisburg, Indiana. Thanks are expressed to Mr. John Monteith, Curatorial Assistant, Department of Invertebrate Palaeontology, ROM, for the restoration of original thin sections and for the preparation of well-oriented new sections necessary for the research, and to Miss Joan Burke for her expert secretarial assistance during the preparation of the text and for the typing of the manuscript. The photomicrographs were taken by Mr. Brian O’Donovan, Department of Geology, University of Toronto. Sincere appreciation is expressed to Dr. John Utgaard, Department of Geology, Southern Illinois University, Carbondale, Hlinois, and to Dr. Alan Horowitz, Department of Geology, Indiana University, Bloomington, Indiana, who kindly read the manuscript. 28 Literature Cited ARMSTRONG, H. S. 1945 Stigmatella in the Ordovician of the Central Ontario Basin. J. Paleont., 19(2): 149-157. BOARDMAN, R. S. 1960 ‘Trepostomatous Bryozoa of the Hamilton Group of New York State. Prof. Pap. U.S. Geol. Surv., 340: 1-87. BOARDMAN, R. S. AND J. UTGAARD 1966 A revision of the Ordovician bryozoan genera Monticulipora, Peronopora, Heterotrypa, and Dekayia. J. Paleont., 40(5): 1082-1108. CORNELIUSSEN, E. F. AND T. G. PERRY 1973 Monotrypa, Hallopora, Amplexopora and Hennigopora (Ectoprocta) from the Browns- port Formation (Niagaran), western Tennessee. J. Paleont., 47(2): 151-220. CUMINGS, E. R. AND J. J. GALLOWAY 1913. The stratigraphy and paleontology of the Tanner’s Creek section of the Cincinnati series of Indiana. 37th Rep. Indiana Dep. Geol. Nat. Resour., 1912: 353-479. 1915 Studies of the morphology and histology of the Trepostomata or monticuliporoids. Bull. Geol. Soc. Am., 26(3): 349-374. D’ORBIGNY, A. D. 1849 Prodrome de paléontologie stratigraphique universelle des animaux mollusques & rayonnés, faisant suite au cours élémentaire de paléontologie et de géologie strati- graphiques. Vol. 1. Paris, V. Masson. 394 pp. DYER, W. S. 1925 The stratigraphy and paleontology of Toronto and vicinity. Part v. The Paleontology of the Credit River section. Rep. Ont. Dep. Mines, 1923, 32(7): 47-88. FOERSTE, A. F. 1924 Upper Ordovician faunas of Ontario and Quebec. Mem. Geol. Surv. Brch. Can., 138: 1-255. FRITZ, M. A. 1970 Redescription of type specimens of the bryozoan Hallopora from the Upper Ordo- vician of Toronto Region, Ontario. Proc. Geol. Ass. Can., 21: 15-23. 1971 The trepostomatous bryozoan Stigmatella catenulata diversa Parks and Dyer (1922), a synonym for Mesotrypa diversa (Parks and Dyer). Life Sci. Occ. Pap., R. Ont. Mus., 18: 1-6. 1973 Redescription of type specimens of bryozoan Stigmatella from the Upper Ordovician of the Toronto Region, Ontario. Life Sci. Contr., R. Ont. Mus., 87: 1-31. INTERNATIONAL COMMISSION ON ZOOLOGICAL NOMENCLATURE 1968 Heterotrypa Nicholson, 1879, and Peronopora Nicholson, 1881 (Bryozoa: designation of type-species under the plenary powers). Bull. Zool. Nom., 24(6): 335-336. LIBERTY, B. A. 1969 Palaeozoic geology of the Lake Simcoe area, Ontario. Mem. Geol. Surv. Brch. Can., S55; 1E201F NICHOLSON, H. A. 1875 Corals of the Cincinnati Group. Jn Description of the corals of the Silurian and Devonian systems. Rep. Geol. Surv. Ohio, 2(2): 183-223. 1879 On the structure and affinities of the “‘tabulate corals”’ of the Palaeozoic period, with critical descriptions of illustrative species. Edinburgh, W. Blackwood. 342 pp. 1881 On the structure and affinities of the genus Monticulipora and its sub-genera, with critical descriptions of illustrative species. Edinburgh, W. Blackwood. 240 pp. PARKS, W. A. 1924 Upper Ordovician at Toronto, Ontario. Bull. Geol. Soc. Am., 35(1): 103-104 [Abstract]. PARKS, W. A. AND W. S. DYER 1922 ‘The stratigraphy and paleontology of Toronto and vicinity. Part 1. The Molluscoidea. Rept. Ont. Dep. Mines, 1921, 30(7): 1-59. SIEGEL, S. 1956 Nonparametric statistics for the behavioral sciences. New York, McGraw-Hill. 312 pp. 29 ULRICH, E. 1879 1882a 1882b 1883 1890 1895 ULRICH, E. 1904 UTGAARD, 1965 UTGAARD, 1964 30 oO. Descriptions of a new genus and some new species of bryozoans from the Cincinnati Group. J. Cincinn. Soc. Nat. Hist., 2(3): 119-131. American Palaeozoic Bryozoa. J. Cincinn. Soc. Nat. Hist., 5(3): 121-175. American Palaeozoic Bryozoa. J. Cincinn. Soc. Nat. Hist., 5(4): 232-257. American Palaeozoic Bryozoa. J. Cincinn. Soc. Nat. Hist., 6(2): 148-168. Part 11. Palaeontology of Illinois. Section vi. Palaeozoic Bryozoa. Jn Worthen, A. H. Geological Survey of Illinois. Volume 8. Geology and palaeontology. Edited by J. Lindahl. Springfield, Ill., Published by authority of the Legislature of Illinois, pp. 285-677. On Lower Silurian Bryozoa of Minnesota. Minn. Geol. Nat. Hist. Surv., Final Rep., 3(1): 96-332. O. AND R. S, BASSLER A Revision of the Paleozoic Bryozoa. Part 1. On the genera and species of Tre- postomata. Smithson. Misc. Collns., 47: 15-55. J. AND R. S. BOARDMAN Heterotrypa Nicholson, 1879, and Peronopora Nicholson, 1881 (Bryozoa, Treposto- mata: proposed designation of a type species in conformity with generally accepted usage. Z.N. (S.) 1693. Bull. Zool. Nom., 22(2): 112-118. J. AND T. G. PERRY Trepostomatous bryozoan fauna of the upper part of the Whitewater Formation (Cincinnatian) of eastern Indiana and western Ohio. Bull. Indiana Dep. Conserv. Geol. Surv., 33: 1-111. =rAG ee ties tape ~ ISBN 0-88854-169-4