植物研究雑誌 J. J. Jpn. Bo t. 73: 73: 26-34 (1 998)

1 Permineralized Permineralized Matoniaceous Fossils from the Cretaceous of Japan )

Harufumi NISHIDA a，Akira YOSHIDA b and Makoto NISHIDA b

aLaboratory aLaboratory of Geosciences and Biology ，Faculty of Science and Engineering ， Chuo University ， Kasuga Kasuga 1-13-27 ，Bunkyo-ku ，Tokyo ，112-0003 JAPAN; bpaleontological bpaleontological Laboratory ，Research Institute of Evolutionary Biology ， 2-4-28 2-4-28 Kamiyoga ，Setagaya-ku ，Tokyo ，158-0098 JAPAN (Received (Received on September 1 ，1997)

A fossil matoniaceous rhizome ，Tricyclopteris japonocretacea gen. et sp. nov. is described described from the Upper Cretaceous of Hokkaido ，Japan. The rhizome has a tricyclic solenotele solenotele with endarch primary xylem. A matoniaceous petiole or rachis ，Matoniostipes mesozoica mesozoica Nishida (1973) from the Lower Cretaceous of Choshi ， Chiba Prefecture ，is emended and reexamined for comparison. It has loose parenchyma (Seward 1899) near protoxylem protoxylem like the petiole of living Matonia pectinata. Matonia pectinata is also characterized characterized by a small cavity parenchyma (Holder ， 1925: Ogura ， 1972) near protoxylem in in the rhizome ， while it does not occur in Tricyclopteris. (Continued (Continued from Y oshida et al.， Res. Ins t. Evolu t. Bio l. Sci. Rep. 8: 85-94 ， 1996)

Introduction on a badl y preserved specimen from the Jurassic The Matoniaceae is a rather small family of of lndia (Sharma and Bohra 1978). leptosporangiate leptosporangiate fern. The family consists of Tidwell and Skog (1992) described two two living genera Matonia (2 spp.) and genera of different ages from Tasmania. Mid- Phanerosorus (1 sp.). Thespeciesarerestricted Mesozoic Tasmanopteris has a polycyclic to to the paleotropical regions and prefer habitat siphonostele and Tertiary Heweria has similar in in forest floor or margin ，though it is well structure. However ，Tidwell and Skog (1992) known from the fossil records that the family state possible Mesozoic origin of Heweria. was cosmopolitan during the Mesozoic. Matoniostipes mesozoica (Nishida 1973) is Fossils that are comparable to the the first record of permineralized matoniaceous Matoniaceae are being found ever since the fossil in the world from the Lower Cretaceous Triassic. Triassic. lmpression or compression fossils of Chiba Prefecture ，J apan. It is emended by such as Phlebopteris Brongniart (1 836) (= reexaminations of type specimen. The fossil Laccopteris Laccopteris Presll838) (the Upper Triassic to which will be described here is a fern rhizome the the Cretaceous) and Matonidium Schenk collected by the first and third authors from the (1871) (1871) (J urassic and Cretaceous) have shown Upper Cretaceous of Yubari City ，Hokkaido. worldwide distribution. Delo ωsorusSk ωog(1988) It has a tricyclic stele characteristic of a

i臼s an Ame 口r-lC 咽 matoniaceous rhizome. The rhizome is com- Cretaceous. Cretaceous. These are all impression or com- pared to the early described fossils and living pression foliage. The first record of Matonia ，and is designated here as a new permineralized permineralized matoniaceous rhizome is based genus of the Matoniaceae.

一一 26 一一 February February 1998 Journal of Japanese Botany Vo l. 73 No. 1 27

Materials Materials and Methods consisting of scalariform tracheids and xylem Specimen No. 82301 is a permineralized parenchyma ， lacking cavity parenchyma fern fern rhizome 6 mm long and 4 mm in diameter ， near protoxylem. Each stele surrounded by with with fairly well preserved histology. It is cy- sclerenchyma tissue consisting of thick - walled lindrical lindrical in original shape ， but one-third of it is cells. degenerated degenerated or lost during the diagenesis. The Etymology. The genus name originates from specimen specimen is embedded in a calcareous nodule the tricyclic stele of rhizome. found found from the riverbed of the Yubari River ， Tricyclopteris japonocretacea H. Nishida ， along along downstream from Hakobuchi dam ， A. Y oshida & Nishida ， sp. nov. Ohyubari ， Yubari City ，Hokkaido ，J apan. The Species diagnosis. As that of the genus. nodule nodule containing the fossil also include ma- Etymology. The specific epithet means the rine rine fauna and shows lithological features of fossil occurrence (J apan) and age (Cretaceous). the the nodules derived from the Upper Creta- Deposition. Micropreparations of the holotype ceous ceous Middle or Upper Yezo Group (Turonian- specimen (No. 82301) is housed in the Labo- Santonian) ，which are widely distributed along ratory ofPhylogenetic Botany ， Faculty of Sci- the the Yubari Rive r. A cyatheaceous tree fern ence ，Chiba University ， Japan. petiole ，Thyrsopterorachis (H. Nishida and Description. Rhizome cylindrical ， without Nishida Nishida 1979) has been described from the prominent dorsiventrality ， 4.0 mm in diameter same area. GeologicaI information should be and with tricyclic stele. The outer and middle referred referred to the previous paper (H. Nishida and steles amphiphloic solenostele ，and the inner a Nishida Nishida 1979). Micropreparations were made protostele (Fig. 2). Epidermis eroded and los t. by ordinary peel method (Joy et al. 1956) using Hypodermallayer consists of sclerenchyma of 1.8% hydrochloric acid as an etching reagen t. 2- 3 cells thick; cells rectangular in cross sec- We used micropreparations of Matonia tion ，12.5-25μm in diamete r. Outer cortex 3- pectinata pectinata made by the late Pro f. P. Maheshwari ， 5 cells wide ，composed ofthick-walled paren- India ， for comparison. chyma ， while inner cortex 7-10 cells wide ， Micropreparations Micropreparations of the type specimen of composed of thin- walled ce Il s; ce Il s 65-75μm Matoniostipes Matoniostipes being deposited at Chiba Uni- in diameter (Fig. 2). Each stelar ring sur- versity versity were compared to the fossil rhizome. rounded by a sclerenchyma sheath of 5-7 cells thick. thick. The sclerenchyma cells 25-37.5μmm Results Results diameter(Figs. 3，4 and 6). Endodermis mostly Taxonomic treatment degraded. Diameter of stelar rings 2.0 mm in Class Class Filicopsida the outer ， 0.9-1.0 mm in the middle and 0.2 Order Filices Leptosporangiatae mm in the central protostele. In the external Family Matoniaceae C. Presl (1 847) stelar ring ， the xylem plate slightly undulates Genus Tricyclopteris H. Nishida ，A. in the inner contour (Fig. 2，between arrows). Yoshida & Nishida ， gen. nov. The xylem chiefly endarch or rarely mesarch Type species. T.japonocretacea H. Nishida ， with ca. 15 protoxylem points.. Metaxylem A. A. Yoshida & Nishida sp. nov. (Figs. 2-6). tracheids have scalariform wall thickening. Diagnosis Diagnosis of the genus. Permineralized fern The most part of phloem degenerated. Xylem rhizome with tricyclic stele; outer and middle mass of the central protostele centrarch and stelar stelar rings amphiphloic and with chiefly consists of less than 10 ce Il s (Fig. 4). Cavity endarch endarch or a few mesarch xylem; innermost parenchyma absent near protoxylem (Fig. 5). stele stele ectophloic centrarch protostele; xylem Affinity. the slender elongated rhizome with 28 28 植物研究雑誌第73 巻第1号 平成10 年2月

Fig. Fig. 1. Cross section of rhizome of living Matonia pectinata showing tricyclic solenostele. Each stelar stelar ring is surrounded by sclerenchyma sheath. Inner contour of the outer ring undulate. U pper side side of rhizome to the righ t. Scale bar: 1 mm. Fig. 2. Cross section of rhizome of Tricyclopteris japonocretacea japonocretacea gen. et sp. nov. ，showing tricyclic stele ， sclerenchyma sheath ，and xylem plate folding folding (between two arrowheads). Scale bar: 0.5 mm. Abbreviations. Abbreviations. Ab: abaxial side ，Ad: adaxial side ， ed: endodermis ， oc: outer cortex ， p: parenchyma ， ph: phloem ， px: protoxylem ，sc: sclerenchyma sheath ， vb: vascular bundle ， x: xylem. xylem. February February 1998 Journa1 of Japanese Botany Vo l. 73 No. 1 29

Figs.3-6. Figs.3-6. Tricyclopterisjaponomesozoica gen. et sp. nov. Fig. 3. Part of outer stelarring ， showing amphiphloic amphiphloic concentric bundle with endarch xylem and surrounding sclerenchyma sheath. Scale Scale bar: 100μm. Fig. 4. Stelar rings enlarged. Scale bar: 100μm. Fig. 5. Outer stelar ring enlarged ， showing absence of cavity parenchyma near protoxylem. Scale bar: 50μm. Fig. 6. Part of of middle stelar ring enlarged. Scale bar: 50μm. 30 植物研究雑誌第73 巻第1号 平成10 年2月

tricyclic tricyclic stele structurally characterizes some parts (Fig. 2，between arrowheads). Tricyclopteris. Tricyclopteris. The amphiphloic concentric The slender rhizome of Tricyclopteris re- bundles bundles and xy lem maturation ，which is chiefl y sembles that of Phanerosorus which is 3 mm endarch endarch or rarely mesarch ， are also character- in diameter ， while Matonia rhizomes range istic istic features. The stelar configuration and from 9 to 10 mm in diamete r. Howeve r. the presence of endodermis attribute the stele of Phanerosorus is dicyclic. Tricyclopteris Tricyclopteris to leptosporangiate ferns. In the Matonia rhizome is characteristic in having living living leptosporangiate ferns ， a polycyclic stele cavity parenchyma near protoxylem (Holder occurs occurs inAcrostichum ，Dennstaedtia ，Matonia ， 1925) (Figs. 7 and 8). Such cavity parenchyma Pteris ，Saccoloma ，and Thyrsopteris (Bower is absent in Tricyclopteris (Fig. 5). 1918 ，1926 ， 1928; Ogura 1972). Acrostichum ， Sharma and Bohra (1 978) reported a Saccoloma and Thyrsopteris differ from Matonia-like silicified rhizome with tricyclic Tricyclopteris Tricyclopteris in having nests of medullary stele from the Jurassic of Rajmahal Hills ， bundles bundles in the pith. The vascular cylinder of India. It is 0.9- 1. 2 cm in diameter and is Pteridaceous Pteridaceous ferns such as Pteris and thicker than Tricyclopteris. The three stelar Dennstaedtia Dennstaedtia shows polycyclosteley with vari- rings are amphiphloic having mesarch xylem able able thickness; usually thicker on dorsal side plate instead of chiefly endarch one in and resulting in a slight dorsiventrality of the Tricyclopteris. The xylem plate is 3-5 cells rhizome rhizome anatomy. thick instead of 1-3 in Tricyclopteris. tricyclic A tricyclic stele similar to Tricyclopteris is Matonidium sp. from Belgium Wealden reported reported in Pteris podophylla Swartz of the (Seward 1910) is a permiileralized rhizome Pteridaceae Pteridaceae (Troop and Mickel 1968). Al- with poorly preserved internal structure and though though the specimen of P. podophylla is not cannot be comp 訂 ed to Tricyclopteris. available available to us ， the general structure of Tidwell and Skog (1992) described two Tricyclopte Tricyclopte ris does not fit that of Pteris. The matoniaceous genera ， Tasmanopteris and outer outer ring of polycyclostely in the pteridoid Heweria from Tasmania ，Australia. Although ferns ferns is distorted in configuration (Bower Heweri αis found from the Tertiary sediments ， 1923) ，unlike a complete circle ofTricyclopteris its preservation type and possible reworked and Matonia. nature suggested the Mesozoic origin (Tidwell Tricyclopteris Tricyclopteris rhizome is slender in com- and Skog 1992). Heweria resembles Matonia pared pared to that of Matonia pectinata. Thinner in having uniseriate ，multicellular epidermal xylem plate of Tricyclopteris is probably due hairs. The tri- to hexacyclic stele of Heweria to to the size difference. Though the innermost differs from tricyclic stele of Matonia and stele stele is solenostelic in mature M. pectinata ，it Tricyclopteris. is is protostelic like Tricyclopteris in a slender Tasmanopteris is characteristic in having rhizome rhizome (Tansley and Lulham 1902 ，1905). In mucilage canals in cortex ，which are absent in

M. pectinat α， ， the dorsal side of the external He v. ノeria andMatonia. Tricyclopteris also lacks vascular vascular cy linder is undulated especiall y along mucilage canals in the cortex. Three 恥1esozoic its its inner contou r. This undulation corresponds genera ， H のveria ， Tasmanopteris and to to that more characteristically expressed in the Tricyclopteris differ from Matonia in the ab- inner inner contour of petiole vascular bundle. In sence of cavity parenchyma near protoxylem. Tricyclopteris ， the inner contour of the outer Tidwell and Skog (1992) reported exarch vascular vascular cylinder does not undulate signifi- xylem maturation for living Matonia and two cantly ，however ， the xylem plate is folded in fossil genera they described. However ，we February February 1998 Journal of Japanese Botany Vo l. 73 No. 1 31

Fig. Fig. 7 ，8. Magnified cross section of Matonia pectinata rhizome ， showing endarch to mesarch xylem ， and protoxylem areas accompanied with cavity parenchyma. Scale bar: 100μm. Figs. 9 ，10. Matoniostipes mesozoica Nishida. Fig. 9. Half of cross section ofthe specimen ， showing C-shaped C-shaped vascular bundle with deeply incurved adaxial ends. Scale bar: 500μm. Fig. 10. Enlarged Enlarged vascular bundle ， showing parenchyma cells near protoxylem areas. Scale bar: 250μm. 32 植物研究雑誌第73 巻第1号 平成10 年2月 could could notconfirm any exarch xylem inMatonia in the cortex which are present in Matonia we have examined ， nor in Tricyclopteris (Figs. (Ogura 1972). 2 and 3). Discussion. From the Upper Cretaceous of Hokkaido ，a large number of permineralized Matoniostipes Matoniostipes mesozoica Nishida in Bo t. fern fragments belonging to a diverse a町 ayof Mag. Tokyo 86: 189 (1 973). genera and families have been described since Emended description. Permineralized fern Stopes and F吋ii (1 910) first described petiole petiole or rachis with matoniaceous vascular schizaeaceous fertile pinnule ，Schizaeopteris ， arrangemen t. Vascular bundle C-shaped with and a fragment of cyatheaceous tree- fern deeply deeply incurved adaxial ends in cross section; midrib ，Fasciostelopteris ，from Ohyubari ， inner inner contour strongly undulate. Protoxylem Hokkaido. According to Nishida (1 991) the present present at inner corner of each constriction. following genera are known to date: Loose parenchyma present on inner side of Cyathocaulis Ogura ， Cyathorachis Ogura ， each each protoxylem. Vascular bundle surrounded Loxsomopteris Skog ， Paracyathocaulis H. by thin sclerenchyma sheath; sclerotic cells Nishida ， Solenostelopteris Kershaw ， 15-35μm in diamete r. Hypodermal tissue Thyrsopterorachis H. Nishida & Nishida ，and consists consists of severalla yers of thick - walled cells ， Yezopteris Ogura. Nishida (1 991) also listed

8-12μm in diamete r. Outer cortical tissue preliminarily a dennstaedtioid petiole or ra 四 consists consists of large parenchyma cells ，28-45μm chis ，and a gleichenioid petiole. in in diameter ， smaller toward vascular bundle. Except for Loxsomopteris (Loxsomaceae) Convex part of wavy xylem plate 10-15 and Solenostelopteris (family incertae sedis) ， tracheids tracheids thick; tracheids ovoid or cocoon- most genera above belong to the Cyatheaceae shaped shaped in cross section ，38-75μm in short and in a broad sense. Schizaeopteris has been com- 55-140μm in long diameters. pared to the extant genus Anemia of the Affinity. Affinity. Matoniostipes mesozoica is a fern Schizaeaceae since it was first described by

petiole petiole or rachis having a vascular a汀 ange- Stopes and Fujii (1910). Yoshida et al. (1996b) ment of Matonia-type (Ogura 1938 ， 1972); a confirmed this affinity based on spore mor- continuous continuous C-shaped configuration with deepl y phology. Recently an Osmundites petiole incurved incurved adaxial ends. Its xylem plate is flat (Osmundaceae) was added to the Hokkaido along along the external side ， but the inner side is Cretaceous flora (Yoshida et al. 1996a). highly corrugated. Another feature of Tricyclopteris is a representative of the Matoniostipes Matoniostipes is a loose parenchyma mass Matoniaceae new to the flora. associated associated with protoxylem ，which is also The Matoniaceae is known to have had a present present in the petiole of Matonia pectinata world-wide distribution throughout the (Seward 1899). Such parenchyma occurs in Mesozoic ， beginning with the Upper Triassic the the outer ring of tricycle stele in the rhizome of foliage Phlebopteris followed by Matonidium ， Matonia pectinata. This parenchyma is simi- Nathorstia ，etc. The permineralized specimens lar lar to the protoxy lem cavity parenchyma which known to date; Matoniostipes mesozoica was found by Holden (1925) in the rhizome of Nishida (1 973) ，a matoniaceous rhizome M. pectinata. As the loose parenchyma was (Sharma and Bohra 1978) ， Tasmanopteris

overlooked overlooked in the original description (Nishida richmondii Tidwell & Skog (1 992) ，H の， veria 1973) ，we emend here the diagnosis of kempii Tidwell & Skog (1 992) and Matoniostipes. Matoniostipes. Matoniostipes ，however ， diι Tricyclopteris japonocret α cea H. Nishida et fers fers from Matonia in lacking mucilage canals al. (present paper) show similar distributional February February 1998 Journal of Japanese Botany Vo l. 73 No. 1 33 pattern pattern to that inferred from foliage the record. 一一一一一 1971. Weichselia reticulata (StokesetWebb) Fontaine Structurally ，Matoniostipes closely resem- from the Wea1den of Be1gium. Mem. Ins t. Roy. Soc. Na t. Belgique Belgique 166: 1-33. bles bles Matonia in having loose parenchyma near Bower F. O. 1918. Studies in the phy10geny ofthe Fi1ica1es VI 1. protoxylem ， but differs from the latter in lack- Pteroideae. Ann. Bo t. 32: 1-68. ing ing mucilage canals in the cortex. Among four 一一一一一一 1923. The Ferns. 1. Cambridge University Press ，Cam- bridge. bridge. 359 pp. rhizomes ，Heweria most resembles Matonia 一一一一一 1926. The Ferns. II. Cambridge University Press ， in in having epidermal attenuate hairs. Cambridge. 344 pp. 一一一一- 1928. The Ferns. III. Cambridge University Press ， One of the largest relatives of the family is Cqmbridge. 360 pp. Weichselia Weichselia (Stiehler 1857) attaining to a con- Brongniart A. 1836. Histoire des vegetaux fossiles; ou recherches siderable siderable size. Weichselia has a massive stem botaniques et geologiques sur les vegetaux renfermes dans les les diverges couches du globe: vo I. 1: 369 -4 88. bearing bearing helically arranged large fronds with Edwards W. N. 1933. On the Cretaceous fern Paradoxopteris ， thick thick petioles ，5 cm in diamete r. The and its connexion with Weichselia. Ann. Bo t. 47: 317-341 ， permineralized permineralized petiole of Weichselia is known pls.14. Holden H. S. 1925. On the occurrence ofca vi ty parench yma and asParadoxopteris(Edwards asParadoxopteris(Edwards 1933 ， Alvin 1971) tyloses in ferns. J. Linn. Soc. London 47: 141-153. having having up to 12 rings of vascular bundles. Joy K. W. ，Willis A. J. and Lacey W. S. 1956. A rapid cellulose Besides Besides many similarities ， Weichselia differs peel technique in palaeobotany. Ann. Bo t. 20: 635-637. Nishida Nishida H. Diversity 1991. and significance of late Cretaceous from the Matoniaceae in having non-laminar permineralized plant remains from Hokkaido ， Japan. Bo t. fertile fertile pinnules ， polycyclic petiole traces ， Mag. Tokyo 104: 253-273. bipinnately bipinnately compound leaves ，and different 一一一一- and M. Nishida. 1979. Thyrsopterorachis ， gen. nov. ， a tree rachis fern from the Upper Cretaceous of Hokkaido ， a町 angement of soral sporangia (Alvin 1968 ， Japan. Bo t. Mag. Tokyo 92: 187-195. 1971; 1971; Taylor and Taylor 1993) and is some- Nishida M. 1973. On some petrified plants from the Cretaceous of of Choshi ，Chiba Prefecture V I. Bo t. Mag. Tokyo 86: 189- times treated as a separate family 202. Weichseliaceae Weichseliaceae (Alvin 1971). Ogura Y. 1938. Anatomie der Vegetationsorgane der Pteridophyten. Pteridophyten. Handb. d. Pflanzenana t. 1. Ab t. 1. 7，Tei I. 2. Gustav Gustav Fischer ，Be r1 in. 476 pp. We wish to express our hearty thanks to Dr. 一一一一一一 1972. Comparative anatomy of vegetative organs of Yasuji Yasuji Fukuda ，Principal of Musashi High the Pteridophytes. Gebruder Borntraeger ，Berlin. 502 pp. School ， for his adequate suggestion to the Presl C. 1838. Laccopteris. In: Sternberg G. K. (Ed.) Versuch einer einer Geognostischen Botanischen Darstellung der Flora histology histology of the fossi l. Gratefulness is also due der Vorwel t: 11 (7-8): 81-220. Leipzich. to to the staff of the Laboratory of Phylogenetic Schenk A. 1871. Beitr 益ge zur F10ra der Vorvel t. IV. Die Flora Botany ， Faculty of Science ，Chiba University der nordwestdeutschen Wea1denformation. Pa1aeoritog r. 19: 203-262 ，pls. 22 -4 3. for for granting us permission to use laboratory Seward A. C. 1899. On the structure and affinities of Matonia facilities. facilities. pectinata ， R. B r.， with notes on the geological history ofthe Matoniaceae. Matoniaceae. Phi l. Trans. Roy. Soc. London ，Se r. B. 191 ・ 171-209 ，pls. 17-20. Endnote 一一一- 1910. plants ，Fossil 11. 624 pp. Cambridge Univ. Pr.， l)Structure l)Structure and affinities ofthe petrified plants London. from the Cretaceous of N orthern J apan and Sharma B. D. and Bohra D. R. 1978. A petrified matoniaceous rhizome rhizome from Amaηola in the R 司mahal HiIIs ， India. Saghalien Saghalien 24. Contributions from the Research Palaeobotanist 28: 457 -4 60 Institute Institute of Evolutionary Biology ，No. 117. Skog J. E. 1988. Reassignment of Aspidium heterophyllum to a Supported Supported by a Grant-in-Aid for Scientific new genus in the family Matoniaceae. Ame r. J. Bo t. 75: 1120-1129 Research Research from the Ministry of Education ，Sci- Stiehler A. W. 1857. Beitrage zur Kenntniss der vorweltlichen ence ，Literature and Sports to H. N. Flora des Kreidegebirges im Harze. Palaeontog r. 5: 47-70 ， 4 pls. Stopes Stopes M. C. and F吋ii K. 1910. Studies on the structure and References References affinities affinities of Cretaceous plants. Phi10s. Trans. Roy. Soc. Alvin Alvin K. L. 1968. The spore-bearing organs of the Cretaceous London Se r. B 210: 1-90 fern fern Weichselia Stiehle r. J. Linn. Soc. (Bo t.) 61: 87-92 34 植物研究雑誌第73 巻第1号 平成10 年2月

Tansley Tansley A. G. and Lulham R. B. 1902. On a new type of fern- Dennstaedtiaceae and related ferns. Amer. Fern J. 58: 64- stele ，and its probable phylogenetic relations. Ann. Bo t. 16: 70. 157-164. 157-164. Y oshida A. ， Nishida M. and Nishida H. 1 996a. A permineralized 一一一 -and 一一一一一 1905. A study of the vascular system of Osmundaceous petiole from the Upper Cretaceous of Matonia Matonia pectinata. Ann. Bo t. 19: 475-519 ，3 pls. Hokkaido ，Japan. Res. Ins t. Evolu t. Biolog. Sc i. Rep. 8: 49- Taylor Taylor T. N. and Taylor E. L. 1993. The Biology and Evolution 56. of of Fossil Plants. Prentice ha l1， Englewood Cliffs. 982 pp. 一一一一， Nishida H. and Nishida M. 1996b. Permineralized Tidwell Tidwell W. D. and Skog ，J. E. 1992. Two new fossil matoniaceous schizaeaceous fertile pinnules from the Upper Cretaceous stem genera from Australia. Rev. Palaeobo t. Palyno l. 70: of Hokkaido ， Japan. 1. Schizaeopteris. Res. Ins t. Evolu t. 263-277. 263-277. Bio l. Sci. Rep. 8: 85-94. Troop J. E. and Mickel J. T. 1968. Petiolar shoots in the

西国治文 a，吉田彰¥西田誠 b .日本の白亜系 産マトニア科鉱化化石 北海道夕張市大夕張の夕張川川床から採集され 比較のため観察を行った現生の Matonia pectinata た上部白亜系エゾ層群に由来するノジュール中か の葉柄には原生木部内側に柔組織が観察された.

ら見つかった根茎鉱化化石をマトニア化の新属・ この組織は Seward (1899) がloose p 訂 enchyma とし 新種，T; ηcyclopteris japonocretacea として記載した. て報告しているが，同様の組織が千葉県銚子市の この根茎化石は細く 内皮を伴う 3 重の同心円状 下部白亜系産マトニア科葉柄化石 Matoniostipes の維管束を持つ.外側の維管束は完全な環状，髄 mesozoica Nishida (1973) にも見られた. Holden 内維管束群を欠く 維管束環に背腹性がない，な (1925) はこれに似た柔組織を Matonia pectinata の どの点でマトニア科と見なされる.外側の二つの 根茎に見出しており 根茎と葉柄の柔組織はお互 維管束環は両師型の環状中心柱で，木部は主とし いに関連があると考えられる.この柔組織は て内原型，中央のものは原生中心柱である.外側 Matoniostipes mesozoica を特徴づけるので，同種の の維管束環は内側がやや波状となり，約 15 の原生 記載を改訂した. 木部を持つ.原生木部の内側に柔組織を伴わない. c中央大学理工学部， b 進化生物学研究所)