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SMITHSONIAN INSTITUTION
UNITED STATES NATIONAL MUSEUM
Bulletin 77

THE EARLY PALEOZOIC BRYOZOA OF
THE BALTIC PROVINCES

BY

RAY S. BASSLER
Curator of Paleontology, U.S. National Museum

L28ecaesee!

W ASHINGTON
GOVERNMENT PRINTING OFFICE
1911

_ BULLETIN OF THE UNITED STATES NATIONAL MUSEUM

Issuep Drcemprr 23, 1911.

: ROE By,
i)

Hiaeuh dA

PEGE UM

ADVERTISEMENT.

The scientific publications of the United States National Museum
consist of two series—the Proceedings and the Bulletins.

The Proceedings, the first volume of which was issued in 1878, are
intended primarily as a medium for the publication of original, and
usually brief, papers based on the collections of the National Museum,
presenting newly acquired facts in zoology, geology, and anthropol-
ogy, including descriptions of new forms of animals, and revisions of
limited groups. One or two volumes are issued annually and dis-
tributed to libraries and scientific organizations. A limited number
of copies of each paper, in pamphlet form, is distributed to specialists
and others interested in the different subjects, as soon as printed.
The date of publication is printed on each paper, and these dates are
also recorded in the tables of contents of the volumes.

The Bulletins, the first of which was issued in 1875, consist of a
series of separate publications comprising chiefly monographs of
large zoological groups and other general systematic treatises (occa-
sionally in several volumes), faunal works, reports of expeditions,
and catalogues of type-specimens, special collections, etc. ‘The ma-
jority of the volumes are octavos, but a quarto size has been
adopted in a few instances in which large plates were regarded as
indispensable.

Since 1902 a series of octavo volumes containing papers relating
to the botanical collections of the Museum, and known as the Con-
tributions from the National Herbarwwm, has been published as
bulletins.

The present work forms No. 77 of the Bulletin series.

RicnHarp RaTHBUN,
Assistant Secretary, Smithsonian Institution,
In charge of the United States National Museum.

Wasuineton, D. C., December 1, 1911.

III

TABLE OF CONTENTS.

Page

PERIELOCUIGL (OMe esa or Sate, ine eae Are ieee ene ty urement Nee aS Og Be al a 1
Distribution of Early Paleozoic Perec AN 2d SERS ROLLINS Ar, ER te RCO AP 3
General (Geolovy of Baltic Russia..::-25--2-2-.2.-).. 2.222. e2<---0 SEAT iA Cae 4
Corio EIS Ura ceierae cet Rete trel tte Pere en, So pale eects Mybeia, ots) eepS ok 8
Aten iere)l ayy ana assoclaledestratasece a eee eee a eee 10

Ayre Umeulitesamdstomentec sc. cmes oa cers Shs wee ate cs tennis Socal meee 10
Ordoyvicitanand Harly Silurian strataressssserescss sass soos eee eee 11

Ag SME DIC hy ONE Ila DOs wma. ctr h ster ml ALM oe eh vice Mane cunt eae a ee cae 11

Buen Glatieonite sandstones. vada ce Ave a sees cise - ae ee ae 11

Bree Glaucomiberlimestone: oe \es tase. cent neers nae yen be oS eee 12

Drop Orthoceras HMmes One yc. tecne! eiacrscrr is opleles eatin cise erate ae 13

Cale chinespheritesplimestonessesa-erea seen: sane eee ee eee 13

Crank kersishale steccen secs ee ae ince ys Sem oe eka tS 14

Ors rmlitter Wed sae tre ce tanner ys ayer ees oie ee eee eee ee 15

Die dewe dimestonierr sem eure Pers web DN teat Peake Sl 15

DS MINE re Deda cases nea hes sence Seat htas S LU Ra SEMEN ile, &v colea 15
WrsmWassr emai Declan ese a oases tai Vents aie eaten Baer. Sore oe ate 15

iE aViesen bere lim es LOMe sete nee re scenes aaa sloth se aacisee eee sae 16

asi ekholmuan dibs orkh olla ie sass ee sehen ee ae eee eee 16
leontolosy: of thexbal te STeaumces cose ees see se scat thc ce haere once e ees 19
Ordovician formations of Upper Mississippi Valley.........-...-.-...--------- 25
LOLS Ph viV CTs ROU Pret sar mec untar ota ua Mis Mice vernon ene Ce mia L ace Sule 26
BECK SRV eT OO UP sate ee hye. Even mame anos eet a) earn a oe Ree en ie 27
The Bryozoan faunas of American Bier River and earliest Trenton deposits. . 27
Ordovician and Early Silurian strata of Arctic America..............-.-..--- 32
SLA orale comrelatlOnsee anon saya us Cais feb nmol eae 0 eee eee. 36
SEITE RIES Ey OZOAT PIAL AS sae erm Nels seta Ween ee Ny Lee cya ede etey ne re, ive ee ee 45
“ATSTRTR OMIT OE 5 ace Pe a ce gn Sa oe rg 46
ip leorra liye eee se weet oleh cae ene tele mae Golhaa rahe a He tece etal © Siateoete 48
Range of Baltic Ordovician and Early Sic Eareaae. So te Peet eter CoN er ate 49
Descriptions of genera and species.........--.-.-- RURAL NS SUR RR: Be 54
CURIOS LOTTE II os Sy fe ee RR a RU re RL Sa iE ae I ANS eR ye 54
Cyclostoma tars es re Ue No MMe ne aoe oe en reer Aa 58

(Cre SWCD Sl Siete iy slate satin Pa ae cell Si IS te ae Bs Ace are US aes Dre pee 112
shirepostomia tamer saemn erin neuelen ) hes Ie ELAM CON Ger n atte NOM a Wt OS uM oa aie 176
Mmaloamatas sae cee ers ee eee cy mete ein a Oe 2 Daan ene ame 177
inteoralgmes set ates ae rte sae ayn ce ie MOR ence Rn s cra tse Catal cs 265
Wadetermined.ceners. and spectes savas teu hes Wen say Ones wees Slate 339
EPaplanantonlonplavessee a san.as fase eee oe ees Seika We neo aime n na Sale ge ones 350
MiaG Ieoreas Sepa He cies Cy epee SR Mak a eneT tab ada UR ce ie ctr eau ae 375

Me cl rah ln ey

LIST OF ILLUSTRATIONS.

PLATES.

Facing page.
1. Geologic map of the Russian Baltic Provinces. (After von Schmidt.)..... 350
2. Early Paleozoic Bryozoa of the Baltic Provinces...........-22.---------- 352
3. Early Paleozoic Bryozoa of the Baltic Provinces........-.....--.----..-- 354
4, Early Paleozoic Bryozoa of the Baltic Provinces...........-..----.------ 356
5. Early Paleozoic Bryozoa of the Baltic Provinces.........-.......-------- 358
6. Early Paleozoic Bryozoa of the Baltic Provinces...........--.----.--...- 360
7. Early Paleozoic Bryozoa of the Baltic Provinces..........--.-....------- 362
8. Early Paleozoic Bryozoa of the Baltic Provinces..........-...--.-..-: Siete (i!
9. Early Paleozoic Bryozoa of the Baltic Provinces...............----.----- 366
10. Early Paleozoic Bryozoa of the Baltic Provinces..............----.---.-- 368
il, Karly Paleozoic Bryozoa of ‘the Baltic Provinees.:...........2.---2-.-.-- 370
12. Early Paleozoic Bryozoa of the Baltic Provinces.............-...---.---- 372
13. Early Paleozoic Bryozoa of the Baltic Provinces..............----------- 374
TEXT FIGURES.

Page.

Fie. 1. Map of Baltic Sea area, showing distribution of Ordovician and Silu-
MAMNtratae, MCAUHEL VOD OCUMMNIG Cs) rae 5 a= coin torre ckaete ia nei rete Pe 5

2. Map of the North Polar region, showing distribution of Silurian strata

in North America and northern Europe, with the hypothetical
Bronce wines aa AtetaW Cllens) sm. \-easetecimeiac eaciac & aiievainie aihetace 40

3. Generalized paleogeographic map, showing supposed distribution of
land and water during Black River and early Trenton times..... 43

4. Bathymetric chart of the North Polar Seas, suggesting routes of
migration for marine organisms. (After Nansen.)...............- 44

5. Vinella repens. a, two colonies, natural size; 6, portion of one of the

colonies, X 18; ¢, another portion of same zoarium, X 18; d, another

specimen, natural size, attached to a fragment of shell; e, small
POLLoN ot same; ls. (AtterUilnichs) ey. sete ctet- cecbeyeyaye sie << 56

6. Heteronema priscum. a, a colony attached to a valve of Obolus,

< 4; 6, a portion of the same, X 20; ¢, parts of two colonies, X 35,

with one growing over another; d, small portion of another zoarium,
GOD ee Ip escty ares ny Se Ze een Ra MepeRA Sen cee Sater otc Re WE ia 58

7. Stomatopora arachnoidea. a, portion of a delicate zoarium, x 9;
b, part of the same, X 20, illustrating the detailed structure...... 60

8. Corynotrypa delicatula. Specimens figured by Ulrich as Stomato-

pora proutana. a, fragment of a zoarium, X 9; 6 and ¢, two groups
of zocecia, X 25; d, several zocecia of unusual size, X 25......-..- 62

9. Corynotrypa barberi. a, portion of the type-specimen, X 9, incrust-

ing a bifoliate bryozoan; b, several zocecia, X 20; c, part of a small
colony, X 9, growing upon a species of Heliolites............... 63

10. Corynotrypa inflata. a and 6, zoarium, natural size, and a portion,

X 9; ¢, three zocecia of same, X 18, showing the porous wall; d,

a vertical section of a zoecium, X 18; e and f, small portion of a

colony, incrusting Rafinesquina alternata, X 9 and X 18; g, out-

= ; line of zocecia, X 18, showing three ‘‘gems” springing from one

Arce mite’ len CO NGbeD RIC De ae aes ates ots ne einai. ae akan cas So 65
VII

VIII

rca:

12.

13.

14.

15.
16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

LIST OF ILLUSTRATIONS.

. Corynotrypa abrupta. a and 6, portions of the type-specimen, X 9
BA, SK DO eae Nee tye secs sets icy tc aiene gee age eye toe te eee
Corynotrypa abrupta. aand 6, portion of a zoarium, X 9and x 20,
IMCrushine/a CLInold COMM joel ieee leew tae er
Corynotrypa schucherti. a and 6, portions of the type-specimen,
incrusting a Streptelasma, X 9; c, several zocecia of the same,

Corynotrypa dissimilis. a and 6, a typical example of the species,
X 9 and X 20, incrusting the epitheca of the bryozoan Diplotrypa
nummiformis; c and d, poorly preserved specimen of the species,
x 9and X 20, growing upon a specimen of Heliolites...........

Mitoclema boreale. Fragment of a zoarium, X 9......--....--...---

Mitoclema? mundulum. a and )b, fragments, natural size, and
< 9; ¢, original of 6, X 18, showing surface character. (After
Ulrich.) d, portion of young example, X 9............- eas

Protocrisina exigua. a to e, Wiman’s views of Crisinella oeilensis.
a, fragment, natural size; b, celluliferous surface, x 10, showing
the circular zocecia and accessory pores; c, noncelluliferous face,
X 10; dand e, two transverse sections, X 19. /fto7z, Ulrich’s views
of Protocrisina exigua. /, two fragments, natural size; g, cellu-
liferous face, X 18, with zocecial openings and accessory pores;
h, noncelluliferous side, X 18, with pores; 7, transverse section,
SOUS reise & sects: a eevsic oie laveienale ere oreiere a sans eee spon eloee oe ae

Protocrisina ulrichi. a, portion of a zoarium, natural size; 6b, another
fragment, showing the noncelluliferous side, natural size, and
enlarged eight diameters; c, celluliferous side of another fragment,

Ceramopora spongiosa. a, portion of a zoarium, natural size; band c,
tangential section, X 9, and portion of same, < 20; d, tangential
section of three zocecia, X 20; e and /, vertical sections, X 9 and

Ceramopora invenusta. a, tangential section, * 20; 6, tangential
section, X 20; c, vertical section, X 20, through a zoarium.......
Ceramopora intercellata. a, edge view of the fragmentary type, x 1;
b and c, tangential section, X 20, and a portion, 35; d, vertical
section, X 20, through one layer of the zoarium..................
Ceramoporella granulosa minor. a, tangential section, < 20; 6, ver-
tical section, X 20, through a single layer of zocecia.-...........
Ceramoporella uxnormensis. aand 6, tangential section, X 20 and
> 35:.¢; verticaleection, “ZOlcn uses cece cee ee ee eee oe
Ceeloclema crassimurale. a, fragment of a zoarium, natural size, with
end view of the same showing the central tube; b, tangential sec-
tion, X 20; ¢, vertical section, X 20, through one side of a zoarium.
Ceeloclema laciniatus. a, Eichwald’s type-specimen, natural size, of
Coenites laciniatus; 6, surface of the same, enlarged............-
Crepipora schmidti. a, vertical section, « 20; b, tangential section,

Crepipora lunatifera. «a, the type-specimen, incrusting Hormotoma

insignis (Hichwald), two-thirds natural size; b, view of the zocecia
at the surface, X 9; cand d, tangential sections, X 20 and X 35,
illustrating zocecial structure; e, vertical section, 20, through
the 70arLUm oo ies s he ck ec ale oki a aie eh no ge
Crepipora incrassata. a, edge view of the type-specimen, natural
size; b, tangential section, X 20; c, vertical section, X 10, cut-
ting two layers of zocecia; d, portion of a vertical section, & 20...

Page.
66

66

67

68
70

70

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74

77

79

80
82
83
84

85

87

88

90

Fie. 29

30.

31.

32.

33.

34.

30.

36.

37.

38.

39.

40.

41.

42.

43.
. Escharopora subrecta. a and b, a typical specimen, natural size, and

LIST OF ILLUSTRATIONS.

Anolotichia rhombica. a, tangential section, < 20; b, another tan-
gential section, X 20; c, vertical section, X 20; d and e, two por-
tions:ola, vertical scctionemmyserene os. oak Pk ee

Anolotichia brevipora. a, vertical section, X 20, exhibiting short,
immature, and mature regions; b, tangential section, X 20, with
tubules in lunaria; ¢;portionof same, KX 352..98-..02. 5252-22252

Anolotichia revalensis. a, vertical section, < 9; 6, portion of the
same, X 20; c, a normal tangential section, X 20................-

Anolotichia impolita. aand 6, surface of a well-preserved example,
xX 9, and X 18; c, small portion of a tangential section, X 18,
showing lunaria and tubuli; d, vertical section, < 9 (after Ulrich) .

Anolotichia impolita. a, fragment of zoarium, natural size; b and ec,
tangentialtand veriicalisections;xeS sass sate oce eee. lee

Anolotichia sacculus.. a, a type-specimen, natural size, with most of
the zoarium exfoliated and showing the impression of the epitheca;
b, vertical section, X 20; c, tangential section, X 20; d, another
tangential section, < 20; e, two lunaria, X 35, exhibiting num-
berand! distribution obtulmiees tes. 2 sass oc eee

Favositella interpuncta. a, vertical section, X 20; 6, tangential sec-
tion, X 20, with structure of zocecia and mesopores.............-

Favositella exserta. a, edge view of a zoarium, natural size; 6, sur-
face view, X 9, of the sectioned type; c, tangential section, < 20,
exhibiting the small prominent lunarium; d, vertical section, x 9,
through portions of two layers; e, portion of the same, X 20, illus-
trating wall structure im: more detail). .--..-2222-2-22-4s-5--.---

Favositella discoidalis. a and b, top and side views of a zoarium,
natural size; c, surface of same, < 9; d, tangential section, X 20;
e and f, vertical section, X 9, illustrating slight variation in struc-
GUM ey Seas eesey seers Spars tothe UA SS vs laceg seat She Shock altaye eiais is SseIMaene Seve

Favositella? punctata. a, celluliferous side of a zoarium, xX 2; b,
basal side of same specimen, X 2; c, tangential section, x 20; d,
VC TIC ASE THOU UD G7, lees nie ay aes A aay 2 ele pate SA acm Pesoll ae

Scenellopora socialis. a and 6, copy of Eichwald’s views of Ceramo-
pora socialis; a, zoarium, natural size, incrusting an Echinos-
pherites; 6, one of the groups of zocecia of the same, enlarged. ...

Fistulipora primeva. a, the type-specimen, natural size; b, sur-
face of same, X 8; ¢c, tangential section, < 20; d, vertical section,
DGo bem poriioniohsamelseetionis swan we eels oe ae ek

Chilotrypa immatura. a, a fragment, X 2, with a few zocecial aper-
tures enlarged; b, tangential section, x 20, showing arrangement
and shape of zocecia; c, vertical section, X 20, with expanding
and contracting central tube; d, transverse section, K 20.......-

Ptilodictya flabellata. a, zoarium, natural size, parted along the
mesial lamina; b, view enlarged, showing longitudinal arrange-
TMETU LY ON ZO OF CLAS serena pe Sena ee NESS | Lee Meee IE

Ptilodictya gladiola. Tangential section, < 20......-..2..-22:---

the basal portion of the same, X 9; c, view of the central part of
the same zoarium, < 9; d and e, two specimens, natural size,
broader than usual; /, surface of the lower part of another example,
X 18, showing unusual conditions; g, tangential section, < 18,
cutting the immature and mature parts of the zoarium; h, portion
OU AVELMCAMEECHION: YON OU is eG ee Bla ae a

Ix

Page.

92

94

96

97

98

99

101

102

104

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108

110

111

114
115

x

Fie. 45.

46.

47.

48.

49.

50.

51.

52.

53.

55.

56.

97.

58.

60.

61.

LIST OF ILLUSTRATIONS.

Pheenopora ensiformis. Wiman’s illustrations of the Borkholm form
of this species; a and b, two small zoaria, natural size; ¢, surface,
S< 10; d; transverse section; SLO see So Ss oe Se eee
Arthropora simplex. a, several segments in their natural position,
life size; b, surface of a well-preserved fragment, < 18; c, several
zocecial apertures of the same, < 35; d, tangential section, x 18;
e; werticalisection, <-US a5 Ane ie SoS Eaters ee
Graptodictya perelegans. a, tangential section, X 20, of the type-
specimen; 6, several zocecia, X 40; c, vertical section, X 20; d,
transverse SECTION) DXn 20. Sy eee age Sees Oe le Sree
Graptodictya bonnemai. a, portion of a zoarium, natural size; b,
tangential section, X 20; cand d, several zocecia of the same, X 40,
with one still further enlarged, x 60; e, vertical section, X 20....
Graptodictya proava. a, Hichwald’s view-of the type-specimen of
his Coscinium proavum, natural size; 6, tangential section of
Hall’s type of Clathropora flabellata, X 30..-..............-..--
Graptodictya proava. a, tangential section, X 20, cutting the stri-
ated edge of a branch and the adjoining zocecia; 6, portion of the
samme: A402, vertical section, >< 20.25.05. oo: ee eee
Graptodictya obliqua. a, the type-specimen, natural size; b, tangen-
iialssection,/)<20: te! averticaliseciion=>@ 20 as.2 ean
Stictoporella cribrosa. a, nearly complete zoarium natural size;
b and c, surface of a specimen with numerous mesopores, X 9 and
a portion X 18; d, vertical section, X 18; e, tangential section of an
average specimen, <1 8 spsc52 5 bei ek as ene ee Ge eee
Stictoporella cribrosa. aand 6, tangential and vertical sections, X
24, of a well-developed Russian example...

: Seinone gracilis. a, Eichwald’s original ane (Bschara saci:

b and c¢, copies of Bichwald’ s illustrations of Micropora gracilis; b,a
zoarium, natural size, and c, surface of same, enlarged...........-
Stictoporella gracilis. a, tangential section, X 20; b, vertical sec-

Rhinidictya mutabilis. a, a young specimen, described as variety
minor, natural size; 6, the usual mature specimen; c, surface view,
x 9, of a young example; d, several apertures of the same, X 35;
e, surface of original of figure b, X 9. (After Ulrich.).............
Rhinidictya exserta. a and 6, two typical fragments, natural size;
c, tangential section, X 20, through mature zone of an old example;
d, vertical section, X 20, of the same specimen..................-
Rhinidictya exserta. a, Eichwald’s original view of this species;
b, view of hisisecond specimen 22 Sail. 2. nen eee

. Phyllodictya flabellaris. a, vertical section, X 20, showing the long,

zocecial tubes; b, minute structure of the interzoccial spaces, X
60; c, tangential section, < 20, with portion of a macula and adjoin-
ing zocecia; d, several zocecia of the same section, X 35.........-
Phyllodictya varia. a, portion of a large zoarium, natural size; 6,
fragment with subparallel margins, natural size; c, surface of the
same, X 9; d, two rows of apertures, X 18; e, surface of an old zoa-
rium, X 9; /, vertical section, X 18; g, tangential section, X 18..
Pachydictya elegans. a, tangential section, X 18; 6, a single zoce-
cium of the same section, X 35; c, transverse section, < 18, Pachy-
dictya foliata, showing the median tubuli distinctly ...........-

Page.

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Fie.

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69.

70.

(8

72.

73.

14,

75.

76.

LIST OF ILLUSTRATIONS.

. Pachydictya elegans. a, nearly complete zoarium, natural size,
branching more frequently than usual; 6, enlargement of surface
of same, X 18; c, fragment, <X 1.5, with young Streptelasma at-

Pachydictya flabellum. aq, fragment, natural size; b, surface of
same, enlarged; c, transverse view of branch. (Copied from
Richwald’s figure of Stictopora flabellum.)................-.-----

Pachydictya flabellum. a, tangential section, X 20; 6, another
tangential section, < 20, showing the appearance in the early
portion of the mature zone; c¢, tangential section of a young exam-
ple, X 20, with open mesopores; d, the usual aspect of vertical
sections, X 20; e, vertical section, < 20, of young specimen. ....

. Pachydictya cyclostomoides. Eichwald’s view of Micropora cyclo-

stomoides. aand 6, fragment, natural size, and a portion enlarged -

. Pachydictya cyclostomoides. a, tangential section, < 20, showing

the large oval zocecia; 6, vertical section, X 20.............-.---

. Pachydictya bifurcata. aand b, two fragments, X 1.5; c, tangential

section, < 20; d, portion of a transverse section, X 20, with well-
UGE VA exo lM ma ELON eswaY UN OKDU Tea eae os soed ee Ns ee hsm Lees Mes ones eye Se
Pachydictya bifurcata. a tog, Wiman’s figures of Rhinidictya bork-
holmiensis. a to d, four fragments, natural size; e, surface of frag-
ment, < 10; /, vertical section, x 10; g, transverse section, X 10;
h to j, Eichwald’s figures of Stictopora scalpellum; h, fragment,
natural size; 7, surface, enlarged; j7, end view of same.......------
Coscinium prenuntium. a, tangential section, x 20; 6, vertical
IS @liohimt Seo SA Dior sa odes mec INT A Lee a ne RRR eG lege one Soa eg
Arthrostylus conjunctus. a, lateral view of the central portion of a
segment, < 18; 6, small portion of noncelluliferous side of same,
papa tan (Ati ere Willer Ghai) ee geek ats VR ee eae ee!
Arthrostylus obliquus. a, side view of portion of a segment, < 18;
b, noncelluliferous side, X 18, of the upper portion of a segment.
(GANG SxcWilO) I Tai(eha pcp ean eg PANE OK cles TARR Bulivis ety she a eS ea
Helopora divaricata. a, fragment, natural size, and x 7; 6, portion of
the same, X 18; c, transverse section, X 18. (After Ulrich.).....
Arthroclema armatum. a, large segment of the primary series, show-
ing a sharply defined, articulating socket, natural size, and x 18;
b, opposite side of another segment of the primary set, X 18; c¢, a
segment of the tertiary series, < 18; d, complete segment of the
secondary set, o<0l Sis ((Aiber Olney) ee os neat oe nose
Sceptropora facula. a, single segment of this fine species, X 18; 8,
vertical section, X 18, through an entire segment; c, transverse
section, X 18, cutting the lower end of a segment; d, transverse
section, < 18, through the expanded celluliferous portion. (After
ALU) Liste Tie ree erect tira a aes areata NM Ngati th one ins eer
Sceptropora francisa. a, group of three segments, natural size; 6,
the largest segment, 9; ¢, basal portion of the same specimen,
< 20; d, tangential section, X 20; e and//, vertical and transverse
SYST RANE! SCAR ee eat BR ed UR SE EC a A
Nematopora delicatulaand N. consueta. a, zoarium, natural size, and
< 18, of Nematopora delicatula; 6, transverse section of same.
(After Ulrich.) cand d, two fragments, natural size, and X 18, of
the Trenton specimens referred by Ulrich to N. delicatula and
here renamed N. consueta.....---..-------- beet erly eat eo

XI

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87.

88.

89.

90.

DU

LIST OF ILLUSTRATIONS.

. Nematopora ovalis. a, zoarium, natural size, of the form described
by Ulrich as Nematopora quadrata; 6, portion of the same, X 18;

c, vertical section, X 18; d, transverse section, X 50; ¢, fragment of
Nematopora ovalis, natural size, and X 18, with five rows of zocecia;

f, another fragment, natural size, and X 18, with only four rows.
(Aiiter Uirichis) 5452 3s se Nine eae ase i. eee ae eee
Nematopora fragilis. a, fragment, natural size, showing mode of
branching; 6, portion of the same, < 18; c, transverse section, X 50;

a) yerticalysectiony 18 qu (Adter Uilrich\.) see cu a. eee sere eee
Nematopora lineata. a, fragment, natural size; 6, surface of same,
< 18; c, vertical section, X 18; d and e, two transverse sections,

< 18; f, portion of e, X 50, showing minute axial canals and wall
siructure.) \(Atter/ Ulrich?) 255. 22S yee eee eee
Glauconome plumula. a to d, fragments of four zoaria; e, noncellu-
liferous side, X 10; f, celluliferous face, X 10; g and h, two trans-
verse sections: << l0uai(Alter Waman: 22 eae eee eee ee
Glauconome strigosa. Wiman’s figures of this species, described by
him as ‘species No. 1”; a and b, two fragments, natural size;

c, view, X 10, of the celluliferous face; d, side view, X 10; e, trans-
VECO SECTION COs hear Nhe stayed ane Siete) See A ee
Rhombopora esthoniz. a, fragment of zoarium, natural size; 6, tan-
gential section, X 20; c, portion of another tangential section, X 20,
cutting a macula; d, vertical section, X 20; e, transverse section,

Nematotrypa gracilis. a, fragment of zoarium, natural size; 6, tan-
gential section, < 20; c, portion of the same, X 40; d, tangential
section, X 50; e, vertical section, X 20; /, transverse section, X 20,
showaneverowwitirironlcentrall oxds*)52c ej. eee ae eee eae

Lichenalia concentrica. a, epithecal side of a fragmentary specimen;
b, portion of a tangential section, < 20; c, a tangential section, X 20;
d, a tangential section, X 6; e, a portion of a tangential section,
x 20; f, a vertical section, X 20; g, a more diagrammatic vertical
Section, 5% 20a ose ete idee ee alk a Se ec

Chasmatopora tenella. Celluliferous face enlarged. (After Hich-
wretch) saa)- ayers i i i hee ete eeiink Ss ell Pep Nas acai aya aia See

Chasmatopora reticulata. Ulrich’s figures of Phyiloporina reticulata,
a and 6, two fragments, natural size, exposing the reverse side;
c, portion of b, X 9; d, portion of a, X 9, showing broader branches;
e, celluliferous side of a fragment, X 18.......-.-.-----........-.

Chasmatopora furcata. HEichwald’s views of Polypora furcata. a,
zoarium, natural size; 6, an enlargement of the nonporiferous
side, showing distinct rows of papillee; ¢, celluliferous face en-
lareed eh a ean Aes vids o eee sumee Sek piss jee se ea ae

Pseudohornera bifida. Eichwald’s views of Thamniscus bifidus.
a and 6, zoarium, natural size, showing the noncelluliferous side,
and: portion of the isame, enlarcede ance eenes see e one er ee eee

Pseudohornera bifida. a, tangential section, X 20; 6, vertical section,
> 20 3"e transverse: SeCtlOn, << 20M aase ia else semen ete ee eee

Pseudohornera bifida. a, an ordinary specimen, natural size; b,
noncelluliferous side of a larger, more complete zoarium, X 2; ¢,
BUTIACE VOL SAIIVe CAs See Eee ee res See ee pea

Pseudohornera orosa. Wiman’s views of his species Thamniscus
orosus. a and 6, two views, natural size, of the many-branched
zoarium; c, noncelluliferous side of a specimen, X 10; d, cellulif-
eroussurtace, < WO sek See eg a a ete ee Ba alee ee ne a et

Page.

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94.

95.

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98.

99.

100.

101.

102.

103.

104.

105.

106.

107.

108.

LIST OF ILLUSTRATIONS.

Fenestella striolata. a, zoarium, natural size; b, nonporiferous side
enlarged; c, small portion of poriferous side, enlarged. (After
TD Glaty, ea Mole Veoe ates ch A a AU gr aa ae Ba ea ee ae Se A

Monticulipora arborea bispinulata. a, one of the type-specimens,
natural size, incrusting a brachiopod fragment; 6 and c¢, tangential
section, X 20, and a portion, X 30; d and e, a vertical section,
Se Okan clip SOES Oper ee ee aye erate sre Se mee ih eyo a Re che

Monticulipora dagoensis. a, tangential section, < 20; 6, portion of
SAIMEM Crash Cs VELLICAlSeCHIOMNe 2 0c ates ce cer = aegis

Orbignyella germana. a, the type-specimen, natural size; b, view
of the usual characters seen in tangential section, < 20; c, tangen-
tial section, X 20; d, portion of the same, X 35; e, vertical section,
X 20, with acanthopores little developed; /, another vertical sec-

Orbignyella expansa baltica. a, tangential section, X 20; b, several
zocecia of the same, X 35; ¢, vertical section, < 10, through an
entire zoarial layer; d, portion of the same section, X 20.-.....-....

Homotrypa similis. a, surface of a Minnesota specimen, X 18; 6,
two portions of a tangential section, X 18, c, vertical section, X 18.
CAtter Wirichy ite scm sa Sonn eifas Sere Mule Mammen selec ate sien) o=.crae

Homotrypa similis. a, fragment of a branched zoarium, natural size;
b, tangential section, X 20; ¢, vertical section, X 20.....--...--

Homotrypa subramosa. a, fragment of a zoarium, natural size; b,
surface of an ordinary fragment, x 9; c, a tangential section, « 18;
d, tangential section, < 18; e, vertical section of a typical example,
SLs ey CAtiters Wilt cay) ieee She ae alle PER ee Se Seelolaneyata cle ote 6

Homotrypa subramosa. a, tangential section of a Russian specimen,
X 20; 6, several zocecia of the same, X 60; c, two portions of a ver-
tiealiseehiont py a20s easy See eS eee Sees bo ice

Homotrypella instabilis. aand 6, two fragments, natural size; c, sur-
face of a well-preserved example, < 18; d, tangential section,
< 18; e, another tangential section, < 18; /, small portion of a
tangential section, X 50; g, vertical section, X 18. (After Ulrich.)

Homotrypella instabilis. a, 6, and c, vertical sections, X 20; d, tan-
gentialisections C202 nse see alee ee ees ee oS as

Homotrypella cribrosa. a, vertical section, X 20; 6, tangential sec-
tions <520 ctsevierall 7O0eClayeG.oo! satu sasee ce noes ees ee

Homotrypella hospitalis crassa. Ulrich’s views of Atactoporella
crassa. a, tangential section, < 18, of the Minnesota type; 5, ver-
tical section of the same, X 18; c, several zocecia in tangential sec-

Homotrypella hospitalis crassa. a, a Russian example, natural size;
b, tangential section, X 40; c, tangential section, X 40; d, e, and f,
three vertical sections, < 20, illustrating the characters in various
DartsrOle MeyZOA GUIs i here be ese ioe Muy Slay sys aie lan slerb ain hate my

Mesotrypa discoidea orientalis. a, 6, and c, top, basal, and side
views of a zoarium, natural size; d, tangential section, X 20; e, a
portion of the same, X 40; f, vertical section, X 20..........--.---

Mesotrypa egena. a, side view of type-specimen, natural size; b,
tangential section, X 20; c and d, portions of the same, X 35;
e and f, two portions of a vertical section, X 20...........-------

Mesotrypa expressa. a, side view of the type-specimen; 6, view of
the same example fractured lengthwise; c, tangential section,
X 20; d, a portion of the same, X 35; e€ si f two vertical sections,

XIII

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Fie. 109.

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i:

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114.

115.

116.

117.

118.

119.

120.

121.

122.

123.

124.

125.

LIST OF ILLUSTRATIONS.

Mesotrypa milleporacea. a, the epithecal side of a fragmentary zoa-
rium, natural size; 6 and ¢, a tangential section, < 20, and several
zocecia, < 35; d, tangential section of the same specimen, X 20;
ep vertcaltseenion, O@ 208. -- pete sata Naa) sueldelo dee ae eee eee

Mesotrypa milleporacea parva. a, a zoarium, X 2; 6 and ¢, a tan-
gential section, X 20, with several zocecia, X 35; d, vertical sec-
UELOWDep> Gor’\! aes eR Ree enn EMRE ey SE tins 6 hme ne 5 -

Dekayella preenuntia and varieties. a, fragment of a variety, natu-
ral size; 6, tangential section, X 18, of the typical form; c, tan-
gential section, X 18, of variety simplex; d, and e, small portions
of two tangential sections, °50; f, vertical section, X 9, of speci-
men with numerous mesopores: g, minute structure of walls in
sections; S501 22 ease RR SE ae a sete eee

Leptotrypa hexagonalis. a, the original type of the species, natural
size, incrusting a Hyolithes; 6, surface of the same, X 12. (After
Ulrich.) ¢, a fragment of limestone with a Hyolithes incrusted by
thisidelicatesbryozoant 3550 Se Cee Se Aerie

Leptotrypa hexagonalis. a, tangential section of the American type
of the species, X 20; b, several zocecia of the same section, X 30;
é, Mebucal section, OC 20s os oe a aes se eee einen ee ee eee

Leptotrypa hexagonalis. a, tangential section, X 20; of a Russian
example; 6, vertical section, X 20; ¢, a vertical section, X 20; d,
tangential seetions e208 fake. Be. ESE tree

Stigmatella massalis. a, side view of the type-specimen, natural
size; b and c, tangential section, X 20, and a portion of the same,
35; d, vertical section, X 8; e, portion of the same section, X 20;
f, part of vertical section, < 20, through a macula................

Stigmatella inflecta. a, side view of the type-specimen, natural size;
b, tangential section, X 20; c, another tangential section, X 20;
d, several zocecia of the same section, X 40; e, vertical section,

Stigmatella foordii. a, a large specimen of Callopora foordii, of the
natural size; b, tangential section of the same; c, vertical section
of thersamies: (CAtter Nicholsont)&: 25: 2b SSS Leh Ree ee

Stigmatella foordii. a, vertical section, X 20; b, tangential section
< 20; c, portion of the same section, X 35; d, another portion,
< 85; e, several zocecia of a tangential section, X 50.........-...-

Stigmatella claviformis. aand 6, two of the club-shaped zoaria, nat-
ural size; c, view of zocecia in tangential section, X 18; d, vertical
section through the middle of a zoarium, X 18. (After Ulrich.)..

Constellaria varia. a, fragment of a zoarium, natural size; 6, surface
of a mature specimen, X 9; c, tangential section, X 18; d, small
portion of the same, X 50, with two mural tubuli; e, vertical sec-
tion of average example, X 18. (After Ulrich.)..............-..-

Constellaria varia. a, tangential section, X 20, cutting several rays
of a macula; 6, vertical section, X 20, passing through a macula. .

Constellaria varia. a, vertical section, X 20, of a small example; 5,
transverse section of the same specimen, X 20.........-----+----

Stellipora revalensis. a, vertical section, X 20; 6, tangential sec-
tion, X 20, illustrating structure of two rays of a cluster..........

Stellipora apsendesoides. A zoarium, X 3, attached to a specimen
of Eghinospherites...: <.cs.-ce- uae eee eeee ee aoe Here EEee ene

Nicholsonella gibbosa. Eichwald’s figures of Heteropora gibbosa;
a, zoarium, natural size; 6, the surface enlarged............--..--

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Fic. 126.

1278

128.

129.

130.

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132.

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135.

136.

137.

138.
139.

140.

LIST OF ILLUSTRATIONS.

Nicholsonella gibbosa. a and 6, top views of two irregular zoaria,
natural size; c, side view of a third specimen of more regular form;
d, an example with low monticules, viewed from above; e, tan-
gential section, 20, through a macula; /, portion of the same
section, X 20, cutting the ordinary zocecia; g, several zooecia, X 40,
illustrating the minute structure; h, verticalsection, X 8; 7, portion
aigtheysam eisectiony \@2Nerere ares kot ok Oe. eee eck ote
Dianulitesfastigiatus. a, side view ofa zoarium, showing the epitheca;
b, top or celluliferous surface, enlarged; c, edge view of a broken
fragment, enlarged, illustrating the uneven fracture; d, the type-
specimen of Dianulites detritus Hichwald, natural size. (After
LONG ON; eG (eae ee eS GN eee Aa tet aa ets
Dianulites fastigiatus. a, vertical section, X 9; 6, part of the same
section, X 20, showing the wall structure; c, tangential section,
X 20; d, another part of the same section, X 40..........-.....
Dianulites petropolitana. a, tangential section, XX 20; 6, vertical
section, X 8; c, several tubes of the same, X 20............-..-
Dianulites petropolitana. a, tangential section of the form “‘hexa-
porites,’’ 20; 6, small portion of the same, X 35; ¢, several
zocecia of a tangential section, X 35; d, vertical section, x 8,
passineuihrovohyva,,.Macula cme kiccance eect iss Aerie claves a ssaese
Dianulites petropolitana. a and 6, side and basal views; c and d,
tangential section, < 20, and wall structure of same much en-
lanced e.andapyvertical.cection, )< 9, and: >@20eeees see sasee see =
Dianulites petropolitana. Ulrich’s views of Monotrypa (Chaetetes)
cumulata, a and c, tangential section, < 9, and a small portion,
xX 35, showing wall structure; 6, vertical section, X 9..-......-..-

. Dianulites grandis. a, the type-specimen, two-thirds natural size, in

side view; b, view showing simplicity of structure seen in the
ordinary tangential section, 8; c, portion of the same, X 20;
d, tabulation in vertical section, X 8, cutting four layers of zocecia;
e& severalitubesof asimeledayer; 20. . <ckeci nee nce ee ee wei oe
Dianulites collifera. a and 6b, type-specimen, natural size; c, sur-
face, X 9; d, the usual aspect presented in tangential sections,
X 20; e, vertical section of several tubes, X 20; f, a zocecium,
455 pill aatancential: seChlome jersey ate e = eu
Bythopora suberacilis. a, an ordinary fragment, natural size; 6,
suriace of specimen, X 9; c, tangential section of a poorly preserved
fragment, < 18; d, vertical section, X 18. (After Ulrich.)-..-....
Bythopora suberacilis. a and b, tangential and vertical sections,
X 20, of a well-preserved Russian example...............-.-----
Eridotrypa eedilis. Copies of Hichwald’s figures of Cladopora eedilis.
aand c, two fragments of the natural size; b and d, enlargements of
ihe sane yee CUM SANS mai ate IS a setin, aS eee eel oe
Eridotrypa edilis. Copies of Ulrich’s figures of Eridotrypa mutabilis.
a, specimen of average size; 6, surface of another example, X 18;
c, tangential sections, X 18; d, a zocecium of the same section, X 50;
CaeViCRb Cl SECTION, Sul Saiew ary leet fe ase See a ee a ele 6
Eridotrypa eedilis minor. Copied from Ulrich’s figures of Eridotrypa

XV

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244

mutabilis minor. a, b, and c, three average fragments; d, surface —

of a fragment, X 9; e, tangential section, < 18; /, vertical section,

Eridotrypa exigua. a, group of fragments, natural size; 6b and c, two
Olt i ISIE OS”) en Sree key os ere AY aN ASS eee Se eeg os

XVI

Fie. 141.

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146.
147.

148.

149.

150.

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152.

153.

154.

155.
156.

157.

158.

LIST OF ILLUSTRATIONS.

Lioclema vetustum. a, a zoarium, natural size, incrusting an
Echinospherites; 6, tangential section, 20; ¢, portion of the
pame: < (353d svertvealisection << 20k AY ok Aca ae eee

Lioclema spineum. a, tangential section, < 9; b, the detailed struc-
ture of an acanthopore, X 40; ¢, portion of a tangential section,
$1205) d: vertical: section.) 2020 282 BR Ae ee eee

Lioclemella clava. a, the type-specimen, natural size; b, tangential
section, < 20; c, vertical section, < 8; d, portion of the same, 20.

Orbipora distincta. a and 6, basal and celluliferous sides of a young
zoarium, natural size, described by Eichwald as Chaetetes hemi-
sphericus; c, side view of the same specimen; d, celluliferous
surface enlarged. CAtter Mich waldi)) 22 (sigs oe apn ae eee

Orbipora distincta. a and 6, top and side views, natural size, of one
of Eichwald’s type-specimens of Orbipora distincta; ¢, celluliferous
face enlarged; d, worn portion of zoarial base enlarged; e, vertical
section; f, g, and h, views of a larger example; 7, side view of
zooeclaltubes: « (Atter Biichywalldt)s = sees oe eee Ce

Orbipora distincta. a, tangential section, X 20; 6b, vertical section,
< 8; c, small portion of the same section, X 20....-.-.......---

Orbipora distincta. a, tangential section, < 20; 6, a portion of a zoce-
Gla. wall, “<< B5 sis eR is ee

Orbipora solida. a, side view, natural size, of the type-specimen;
6, tangential section, <X 20; c, vertical section, X 8; d, another
vertical section, X 20.....--------- SEeiap taste Fes EAN 3 ae ee eae

Orbipora acanthophora. a, type-specimen, natural size; 6, tangen-
tial section, X 20; c, several zocecia of the same section, x 20;
ds, vertical section yc 620) cis tie 2k ree ea se ee ee

Orbipora indenta. a, the type zoarium, natural size; b, tangential
section, X 20; c, portion of the same section, 35; d, vertical
pection, S< 20: sick Peels NEU ck ai aed a re | pny ae

Esthoniopora communis. a and 6, two vertical sections, X 20.....-

Esthoniopora communis. a, side view of an average specimen, natu-
ral size; b, basal view showing epitheca and cicatrix of attachment;
c, tangential section, X 20, of average zocecia; d, several zocecia of
the same section, X 35; e, vertical section, X 8; /, portion of the
SAME SECHOM, OX ZO se Lee Lae ee ees re 2 pal 1a US ee ene ete

Esthoniopora communis. 4a, tangential section, X 20; 6, vertical sec-
tion, < 20; c, a zocecial tube of the same section, < 20; d, vertical
section, < 20l.0. 2 ae Cen Cae ic, Ok Re ee

Esthoniopora communis. a, tangential section, X 20; b, vertical sec-
tion, X 6, through a single zoarial layer; c, a portion of the same,

Esthoniopora communis. An unusual form of zoarium, natural size. .
Esthoniopora curvata. a and 6, side and basal views of a normal
example, natural size; c, tangential section, < 20; d, vertical section
x 8, through portions of two layers; ¢, another vertical section, X 20.
Petalotrypa folium. a, surface of the type-specimen, X 9; }, tan-
gential section, X 20; c, a few zocecia of the same, < 40; d, vertical
BECtLOMy, TAO es ME ey in ik 20 te ea ge Caen Aa Rar ce
Trematopora primigenia. a to ¢, three fragments, natural size; d,
base of a zoarium, life size; e, surface of a typical example, X 9;
f, surface of another specimen, X 18; g, the usual appearance in
tangential section, X 18; h, several zocecia of the same section, X 50;
4, vertical) section, 18: . (After Ulnich:.)22 29. esse eee

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269

LIST OF ILLUSTRATIONS. XVII

Page.
Fie. 159. Trematopora kuckersiana. a, tangential section, 20; b, vertical

section, X 20; c, another vertical section...........-....2....-.- 270
160. Trematopora cystata. a and b, two fragments, natural size; c, tan-

gential section, X 20; d, several zocecia, X 40; e, vertical section of a

Joramchis: sisi eae Saeed eae vier ues ui shad el 271
161. Batostoma magnopora. a, small specimen of natural size; 6, tan-

gential section, X 18; c, part of axial region in transverse section,

xX 183d, vertical section of zoarium with a narrow mature zone, x 9.

Cher Wilniche esse hse erae le Cee Oa ae ire A os 273
162. Batostoma magnopora. a, a small Russian example referred to the

species, natural size; b, tangential section of same specimen, X 20;

cand d, vertical section, X 10, and a portion, X 20............... 273
163. Batostoma fertile. aand b,a large and a small specimen, natural size;

c, surface of the larger specimen, X 9; d, tangential section of the

same example, < 18; ¢, vertical section, natural size, and a portion,

x SC MiterWlnichy): seh 24. Sele eed ta eee ee 275
164. Batostoma fertile circulare. a and 6, surface of a typical example,

x 9, with a portion, x 18; ¢ and d, two tangential sections, 18,

from different parts of the mature zone. (After Ulrich.)............ 276
165. Batostoma mickwitzi. a, tangential section, < 20; 5, vertical section,

8; c, several tubes of the mature zone, X 20, in vertical section;

dy vertical section; </ 20s ses) 2228. ew i oad es Pee 277
166. Batostoma winchelli. aand 6, two fragments of natural size; c, sur-

face of a, X 9 and X 18; d, tangential section, X 18; e, small por-

tion of a tangential section of a young specimen, X 18; /, several

zocecia of figure d, X 50; g, vertical section, < 18, of an ordinary

Specimens: (Giiter: Wiriehy ier eo SO. eae Boe IS 2 278
167. Batostoma winchelli spinulosum. a, a Russian example, natural

size; b, tangential section, X 20; c, several zocecia of another

tangential section of the same specimen, X 20, exhibiting the

normal development of acanthopores noted in American examples;

diwerticali section | xo 20 Hae 282 WP RHIS eSek 1 SE a 279
168. Batostoma winchelli spinulosum. aand 6, tangential section,’ x 18,

and a single zocecium, X 50, with numerous acanthopores. (After

Wiievehi.): Se oil 1 a ae arenes ia). cea ian eae en ant toe 280
169. Batostoma granulosum. a, the sectioned type-specimen, natural

size; b, tangential section of mature zone, X 20; c, vertical section,

170. Hemiphragma tenuimurale. a, the Russian example sectioned,

natural size; b, view of tangential section; c, vertical section, X 20. 282
171. Hemiphragma tenuimurale. Ulrich’s views of the Minnesota types.

a, surface of specimen, < 9; 6, vertical section, X 18; c, tangential

SEC HOT GAS SUSIE LB SRO AB ee eas alee 288
172. Hemiphragma irrasum. Views of the Minnesota types, after Ulrich.

a and 6, two fragments, natural size; c, surface of an average

example, X 9; d and e, tangential sections, 18; /, vertical

BOC HOMOL-DTAMCHT SON. Gis PAU Se oO, 284
173. Hemiphragma irrasum. a, view, natural size, of a zoarium; 6,

tangential section of the same specimen, X 20; c, several zocecia.

Soon Guvierticalisection Ore ted ile Raced tee tk see ee oo 285
174. Hemiphragma panderi. a, vertical section, x 20; 6, the usual view
seen in tangential section, X 20; c, portion of same, X 40.....-.-- 286

92602°—Bull. 77—11——2

XVIII

Fie. 175.

176.

tie

178.

179.

180.

181.

182.

183.

184.

185.

186.

187.

LIST OF ILLUSTRATIONS.

Hemiphragma glabrum. a and 6b, two fragments, natural size;
c, basal portion of a zoarium, natural size; d, tangential section,
X 20; e, vertical section, X 20; f, several zocecia of a tangential
section wea bs ek cde ie Lemna Beets) nla eR ee
Hemiphragma pygmeum. a, side view of a typical specimen, X 2;
b, an ordinary tangential section, < 20; c, portion of the same, X 35;
d, wertical:sections e020 sane Wace eee Se ee eee ee
Hemiphragma multiporatum. a, side view of the type-specimen;
b, tangential section, X 8; c, portion of the same, X 20; d, vertical
section, X 20, including a macula; e, a part of the same sec-

Hemiphragma subsphericum. a and }b, two portions of a tangential
section, X 20 and x 8, in each case cutting a macula; ¢, zocecia of
the same section, < 40; d, vertical section, X 8; e, part of the
same section x<e20e 1s wots TAs ene a Ee eee

Hemiphragma subsphericum. a to d, four views of zoaria, natural

Hemiphragma rotundatum. a, side view of the type-specimen,
natural size; 6, tangential section of the type, X 20; c, a vertical
section, X 20, illustrating the tabulation of both zocecia and
mesopores;) di afew zoceciaw abate: feceeto: See eee eee

Hemiphragma maculatum. a, a fragment, < 2, exhibiting portions
of two macule; 6, tangential section, X 20, through the inter-
macular zocecia; c, several zocecia of the same section, x 40; d,
Vertical section 620 ied ees, Ae eet fe a ee Re

Hemiphragma batheri. a and b, two fragments, natural size; c, a
tangential section, X 20; d, vertical section of a branch, x 20....-

Anaphragma mirabile. a, view of branch, natural size; 6, tangential
section, X 20; c, several zocecia of another part of this section, X 20;
d, a vertical section, X 9; e, portion of the same section, X 20,
showing the structure in more detail.............-......-.-------

Anaphragma mirabile cognata. a, view of fragment, natural size; 6,
tangential section, X 20; c and d, vertical section, X 8, and a por-

Dittopora claveeformis. a, tangential section, < 20; 6, vertical sec-
tion of the same specimen) S@204% -. (Asati Pen. See
Dittopora annulata. Copy of Hichwald’s illustrations of Cheetetes
annulatus. a, fragment of a normal mature zoarium, natural size;
b, small portion of the same magnified; c, end view of a fragment en-
larged; d, view of cellsin section; eand /, fragment of an old example
and a portion enlarged; g, end view of branch, magnified. .......-
Dittopora annulata. a, tangential section of a mature example, X 20,
passing through the outer deposit of interzocecial tissue in which
the mesopores are barely visible; 6, another tangential section,
< 20, cutting a macula at a lower level and exhibiting the meso-
pores; c, vertical section, X 20, of a young example, showing the
occurrence of semidiaphragms in the bend from the immature to the
mature region; d, similar section of an older specimen, X 20, with
the mesopores well developed and their outer portions filled by

188. Dittopora colliculata. Eichwald’s figures of Trematopora colli-

culata. aand 6, fragment of zoarium, natural size, and surface of
same, Venlarged.2/<.. (5 idiae ee Se ae ee ear a ee Eee peace

Page.

288

289

291

292

293

294

296

297

298

300

303

304

305

Fie. 189.

190.

191.

192.

193.

194.

195.

196.

197.

198.

199.

200.

201.

202.

°

203.

LIST OF ILLUSTRATIONS.

Dittopora colliculata. a, tangential section of a young example, 20,
showing the characteristic shape of zocecia and the larger set of
acanthopores; 0, vertical section of the same specimen, X 20.....

Dittopora colliculata. a, small portion of a tangential section, < 20,
with the walls of the mesopores visible. The large and small set
of acanthopores are clearly developed; 6, another tangential sec-
tion, X 20, with the mesopores and small ancanthopores obliter-
ated by the interzocecial tissue. This thin section was prepared
from a specimen identified by Dybowski as Trematopora pustu-
lifera; c, vertical section, X 20, showing the occurrence of semi-
diaphragms only in the bend to the mature zone .............-.--

Monotrypa jewensis. a, profile view of a small zoarium, natural size;
b, surface of the same specimen, X 10; ¢, vertical section, < 8,
illustrating the crinkled walls and few diaphragms; d, portion of the
same section, X 20; e, tangential section, 20, cutting a macula;
jf, another tangential section, X 20, with numerous young zoecia
mesembluinpy meso pOLestse hes «Suse MS SUES es De Sees ow oe

Diplotrypa petropolitana. Nicholson’s illustrations of Monticulipora
(Diplotrypa) petropolitana, introduced for comparison. a, profile
view of an average specimen, natural size; b, basal view of same
showing wrinkled epitheca; c, tangential section, X 20; d, vertical
section through an immature and a mature zone, X 20.......--

Diplotrypa petropolitana. a, tangential section, < 20; 6, a portion
of the same, X 35; c, vertical section, X 8; d and e, portions of
DeViCrviCASectlOmy GZ OMe es Are CeRe tee tat VAL Ue AE Rec

Diplotrypa petropolitana. a, small portion of a tangential section,
xX 8; 6, parts of same section, <X 20; c, vertical section, x 8;
Ge PORTION POL Sale yy xera 0 Suse ene a ALE cee Ie OS OE

Diplotrypa petropolitana. a, vertical section, X 8; 6, portion of the
same section, X 20; ¢, another portion, < 20; d, vertical section,
< 20, through a macula; e, a tangential section, X 20-......-----

Diplotrypa bicornis. a, an example natural size; 6, and c, two views
of the surface, enlarged. Copied from Eichwald’s figures of Cerio-
OLA TCORMIG + saeco enias Are 2 Oe te om thee, ON ASB oo

Diplotrypa bicornis. a, vertical section, X 20; 6, small portion of
the same section enlarged; c, a tangential section, X 20.......-.--

Diplotrypa bicornis. a, tangential section, X 20; 6, part of the same
section, X 40; c, vertical section, X 20; d, vertical section, < 40- -

Diplotrypa moniliformis. a, side view of a zoarium, natural size;
b, tangential section, X 20; c, vertical section, < 8; d, portion of
t'elsamlersec tion tye 2OMIES: Salat A REE ee SENG EL UE ere

Diplotrypa hennigi. a, side view of a zoarium, natural size; },
tangential section, X 20; c, vertical section, X 20....----.....-

Diplotrypa westoni. a and 6b, side and basal views of a zoarium,
natural size; c, tangential section, X 8; through a macula and
adjoining zocecia; d, portion of the same section, < 20; e, vertical
section, X 8; cutting a macula; /, several tubes of thesame, X 20. -

Hallopora multitabulata. a, view of typical specimen, natural size;
b, surface of the same, X 9; ¢, surface of a finely preserved exam-
Die. Saal Shad, wericaly sections O40. ele Me, PRIS. oe

Hallopora goodhuensis. a and 6, two fragments of natural size;
c, surface of a specimen, X 9; d, axial region of a transverse sec-
LOH Gel eh a CAMLeL WO lnich.) 525s ace soca sees cers emie ce ek wed etesiocme

XIX

Page.

307

308

311

313

314

315

316

317

318

319

321

322

324

326

327

XxX

Fie. 204.

205.

206.

207.

208.

209.

210.

211.

212.

213.

214.

215.

216.

217.

218.

219.

220.

221.

LIST OF ILLUSTRATIONS.

Hallopora goodhuensis. a, tangential section, X 20, of a small speci-
men; 6, vertical section of the same specimen, X 20.-...........
Hallopora wesenbergiana. a, tangential region, X 20; 6, tangential
section, X 20; c, vertical section, <X 20, showing characteristic
baloulation seep et ee a Ss BE Re ar ALR ee
Hallopora splendens. a, fragmentary specimen, natural size; 6, tan-
gential section, X 20; c, usual aspect of tangential sections, < 20;
d, vertical section, X 20; e, another vertical section, X 20........-
Hallopora dumalis. a to d, view of four representative fragments,
life size; e, surface of the slender specimen, X 9; /, surface of
another specimen, X 18; g, vertical section, x 18; h, tangential
sections 18). <(Adter Uirichs) caucus Pe. Lee eee
Hallopora undulata. a and 6, typical specimens of the natural size;
c, surface of original of figure 6, X 9; d, vertical section, x 18.
(Atter Wilnich:)e. Si aca. mee Lee pppoe re US. Se coe eee
Hallopora tolli. a, small fragment, natural size; 6, tangential section,
X 20; cand d, two portions of a vertical section, X 20, exhibiting
tabulavions «...2sassieine Sowers a ose eee et eee
Hallopora elegantula. a, tangential section, < 18; 6, transverse
section, X 18; c, tangential section, X 20, through the mature zone;
dand e, two vertical sections, X 18 and X 20, showing slight differ-
ences; f, surface view of several zocecia, X 20 .-.......------.---
Hallopora ? dybowskii. a, tangential section, X 20, with zooecia less
angular than usual; 6, vertical section, X 8, showing curved
diaphragms; c, several tubes of the same, X 20...............---
Hallopora ? dybowskii. a, side view of a small example, natural
size; b, basal view; c, an average tangential section, < 20; d, ver-
tical section, X 8; e, portion of the same, X 20; /, a long vertical
BEC HOT: SOBs eee ea a es as oe es ee
Hallopora ? tenuispinosa. a, an ordinary fragment, natural size;
b, tangential section, X 20; c, portion of the same, X 35; d, vertical
section, < 20; e, portion of a transverse section, X 20.....-..--..-
Archeopora lamella. Eichwald’s views of his type-specimens, one
(a and 6, natural size and enlarged) showing mesopores, and the
second (¢ and d) apparently with solid interzocecial spaces.....--
Archeopora angulosa. aand 6, the incrusting type-specimen, natural
size and enlarged, showing angular zocecia and open mésopores.
(After Bichwald.): 3: 202 S74 dade beni eas Ja
Archeopora punctata. aand b, the type-specimen, natural size and
enlarsed«: \(Aiter Michwald)ees S388 iec eas. ois eee eee
Archeopora radians. a and b, the type-specimen, natural size and
enlarged, (Adter Hichwald).222 2803.3 [Saeed doe e eee
Calamopora reticulata. a and 6, zoarium natural size and surface
enlarced- «(After Bichwald) sic 2S. Sou. eh saa: See
Dianulites apiculatus. a to d, four views of Eichwald’s type of
Cheetetes apiculatus; e, celluliferous surface enlarged. (After
Eichwalds\5\tecil et eet ice 2 cutee tee er sie en pee ae ae
Micropora rhombica, Fragment of zoarium, enlarged. (After
Bichwald.)ovcsatss par edange Be ok eee ee a le ee eo cee =
Myriolithes fastigiatus. a, the type-specimen, natural size and
slightly enlarged. (After Hichwald.)...................2.2.---

Page.

328

328

330

Bol

332

333

335

336

337

339

340

341

341

342

343

344

345

346

LIST OF ILLUSTRATIONS. XXTI

Page.
Fia. 222. Orbipora fungiformis. a and 6, celluliferous and epithecated sides
of the type-specimen; c, celluliferous surface enlarged; d, basal
Sider emlanme die termine yep emai alpaca se acai eae a Mila, dab Sie wae cs Dae 346
223. Pteropora pennula. aand b, Eichwald’s views of the type-specimen,
marbiralustverandsenmlaraedey as sna ere er nae ee ae 347
224, Pteropora exilis. a and 6, zoarium natural size, enlarged. (After
Bac hnwall cle) \aiacierase eae eter ect Mei tee Nay MB rasa Ser Pea Sar 347
225. Stictopora scalpelliformis. a, Eichwald’s figure of the surface en-
larged; 6 and c, Hichwald’s original figure of the same species.... 348

226. Vincularia megastoma. a and 6, type-specimen, X 1 and enlarged;
€, cross-section of same. (After EKichwald.)......-...:..-...---- 348

Aton

THE EARLY PALEOZOIC BRYOZOA OF THE
BALTIC PROVINCES.

By Ray 8. Bassuer.
Curator of Paleontology, United States National Museum.

INTRODUCTION.

The Cambrian and Ordovician strata of Baltic Russia have been
the occasion of many paleontologic memoirs, mainly because the
rocks are composed in part of unconsolidated materials yielding an
abundance of most beautifully preserved fossils. The exquisite
preservation of these specimens, especially the trilobites, is attested
in museum collections the world over. The large number of species
in these strata is evident when it is known that in 1860, in his Lethea
Rossica, Kichwald described or recorded the occurrence of no less
than 500 Ordovician forms and that since then many more species
have been added to the faunal list by other students. In this host
of species only a few American forms were recognized, indeed, almost
invariably no attempt has been made by either European or American
students to identify trans-Atlantic species. The splendid trilobite
fauna of the Russian Ordovician is undoubtedly the best known and
most completely described. Next in importance come the brachio-
pods and echinoderms, particularly the cystids, which have received
very detailed study. The mollusca, although numerous in described
species, still require much investigation, but the ostracods and the
bryozoans are the least known of all the classes.

In the present work I have endeavored to present as complete a
study of the Russian Ordovician Bryozoa as the available collections
would allow. It was my intention to limit the work to this subject,
but in the course of study several additions have been made. First,
the description of a single Cambrian form, of especial interest in being
the oldest known bryozoan, was added. Then, when the studies
were nearly completed, the authorities of the British Museum sent to
the United States National Museum for determination, two collec-
tions of Bryozoa obtained by Dr. F. A. Bather, from certain Ordo-

1

2 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

vician formations on the island of Oeland, in the Baltic Sea. These
contained faunas so intimately related to those of the Russian prov-
inces that I have incorporated the results of their study. In addi-
tion I have presented an account of the stratigraphy and detailed
lists of species of both the Baltic area and the American region which
the Russian faunas and formations most closely resemble. The
study of these bryozoan faunas has indicated that the greater part
of the Russian Ordovician section may be directly correlated with
the Black River group of America, while the Upper Lyckholm and
Borkholm limestones are the equivalents of the Richmond group.

Recent studies based upon paleontologic and diastrophic criteria
have indicated that the Richmond group of America, with its equiva-
lent in Baltic Russia, the upper part of the Lyckholm and the Bork-
holm limestones, should be classed as earliest Silurian. The bryozoan
faunas of these several formations afford ample evidence of this fact,
thus making it advisable to add their description and discussion to
the present work.

Summing up; the paleontologic portion of this paper includes the
description of a single Cambrian bryozoan, of numerous Ordovician
species from the Baltic provinces of Russia and Sweden, and, finally,
of the faunas of the early Silurian, the Upper Lyckholm and the
Borkholm limestones.

In the course of a general study of the West-European Paleozoic
rocks in the summer of 1903, Prof. Charles Schuchert, at my
request, gathered as many Bryozoa as possible from the Ordo-
vician rocks outcropping in the shore region of Esthonia, Russia,
between St. Petersburg and Reval. He was fortunate in hay-
ing as companions during this trip Prof. Friedrich von Schmidt,
and Dr. August von Mickwitz, whose authoritative knowledge of the
geology and paleontology of the region made these collections of
unusual value for stratigraphic purposes. Later, through Prof.
Schuchert, these collections were increased by the generous gift to
the United States National Museum, from Dr. Mickwitz, of his fine
lot of Russian Ordovician Bryozoa, this gift being made upon the
conditions that the collection be studied and a named set
be returned to the donor. Prof. George Mikhailowski, director
of the University Museum at Dorpat, was also kind enough
to loan collections of these fossils in his museum, which were of
especial value since they had been studied and labeled by Dybowski.
I am also indebted to Dr. F. A. Bather, of the British Museum, for
the loan of the bryozoan material collected by him from several of
the Swedish formations on the island of Oeland. In this way a con-
siderable amount of material was at my disposal for study, and a
detailed comparison of these various bryozoan faunas with those from

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 3

America was made possible. My studies on these collections have
been in progress for some years, but other duties, as well as the large
amount of labor required to study and illustrate the faunas, have
prevented prompt publication.

During the progress of these studies I have had the continued
advice of my friends, Dr. E. O. Ulrich, of the United States Geological
Survey, and Prof. Charles Schuchert, of Yale University, to both of
whom I am under obligations. As many of the Russian forms have
proved to be identical with American species described by Dr. Ulrich,
it has been my especial good fortune to enjoy the benefit of his mature
judgment upon difficult and debatable points. Prof. Schuchert has
kindly read and criticized that part of my manuscript dealing with
the geology and stratigraphy. I am also indebted to Miss Fran-
cisca Wieser, who, in her usual skilled manner, has prepared many
of the drawings and has retouched all of the photographs illustrating
this volume. The illustrations of the internal structure were drawn
under a camera lucida by myself.

In order that a representative collection of these bryozoan faunas
should be available to European students, the United States National
Museum has forwarded an almost complete set of the species herein
described to the British Museum. On the other hand, the authorities
of the British Museum have deposited a good set of Ordovician bryo-
zoans from the island of Oeland in the collections of the United States
National Museum. As a result of this exchange of material, the
collections of both institutions have practically a complete representa-
tive set of these species. A second quite complete set has been
placed in the Mickwitz collection, now preserved in the museum at
Reval.

DISTRIBUTION OF EARLY PALEOZOIC BRYOZOA.

The exceeding richness of the North American Ordovician strata
in Bryozoa has long been known, and ‘‘monticuliporoids” from the
Cincinnati and other regions usually form a part of every paleonto-
logical collection. At the present time about 500 species of Bryozoa
have been described from American strata of this geologic period,
and an equally large number of new forms is known. With further
searching it is almost inevitable that many more new species will be
discovered—indeed, a conservative estimate would place the described
species at not more than one-third of the probable number of Ordo-
vician forms. The oldest known American form is a new species of
Nicholsonella occurring in the Beekmantown rocks of Arkansas.
Exclusive of this occurrence, the class is unrepresented in America
until the Stones River division of the Mohawkian is reached, when a
prolific fauna is encountered.

4 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Fortunately for correlation purposes the described forms are
almost entirely from standard Ordovician sections in which the
position and range of each species is fairly well known. Thus, in
New York and Canada at least the characteristic bryozoans of the
various horizons have been determined; in the Cincinnati uplift a
large fauna has been described; in Illinois the faunas of formations,
either poorly represented or absent in the other regions, are partially
worked out, while, finally, the species of the Middle Ordovician in
Minnesota have been published in considerable detail.

In marked contrast with this prolific representation is the exceed-
ing scarceness of Bryozoa in most of the Ordovician areas of Europe.
In the British Isles very few species have been noted, partly because
the strata here are mainly slates and sandstones, indicative of condi-
tions ill fitted for bryozoan life. Similar conditions obtain in the
Bohemian Ordovician, and correspondingly few bryozoans are
known. The Ordovician of Spain and France has likewise yielded
few specimens of this class. However, certain limestones in Scandi-
navia and most of the Ordovician and early Silurian formations of
western Russia abound in Bryozoa, and it is with the faunas of these
two areas that the present work is concerned.

GENERAL GEOLOGY OF BALTIC RUSSIA.

The lower Paleozoic formations of Russia outcrop in a broad belt
extending from Lake Ladoga westward to the islands of Oesel and
Dago, where they are hidden to a great extent by very recent deposits.
The extent of outcrop and the larger unconformities are indicated on
the accompanying map published by Dr. F. von Schmidt (PI. 1),
which is introduced to show the location of the various fossil localities
in addition to the geology. This belt of outcrop continues under the
Baltic Sea in a broad curve to the southwest, for essentially the same
formations of the lower part of the section are exposed on the island
of Oeland. The Borkholm limestone is known to outcrop under the
Baltic because of the numerous bowlders containing this fauna in the
drift on the island of Gothland. These drift bowlders have been
carefully studied by Wiman, who has published an excellent paper
upon the subject entitled ‘‘Uber die Borkholmer Schicht im Mittel-
baltischen Silurgebiet.”! The accompanying sketch map (fig. 1),
modified after a chart by von Schmidt, shows the distribution of
the Ordovician and Silurian rocks in this western portion of the
Baltic area.

The Cambrian and Ordovician deposits of the area are of unusual
interest in that they are made up in considerable part of unconsoli-

1 Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, No. 10, 1902, pp. 149-222, pls. 5-8.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 5

dated materials. Their strata in certain portions of the Baltic
provinces have apparently never been covered by younger deposits
and have been so little disturbed that the sediments often have
remained as originally deposited. As a result the included fossils
are in an especially fine state of preservation.

In spite of this apparently undisturbed condition of the strata
both the paleontologic and stratigraphic records show great time
breaks in the sequence. Thus the entire Middle Cambrian is wanting,
and, according to the present results, the greater portion of the
North American Ordovician section is absent.

\

WY Obersilur.
Untersilur:

Fic. 1.—MapP oF BALTIC SEA AREA, SHOWING DISTRIBUTION OF ORDOVICIAN AND SILURIAN STRATA. (AFTER
: VON SCHMIDT.)

The Cambrian and Ordovician strata of the Baltic area have been
divided by von Schmidt into six general divisions, designated by the
letters A to F. In an earlier classification the same author recog-
nized three zones with several subdivisions. The lettered divisions
have since had geographic names applied to most of them, although
in a few cases a lithologic designation, or the name of a characteristic
genus of fossils has been retained. These several classifications are
tabulated on the following page.

6 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Table of Cambrian and Ordovician formations in Russia.

[After von Schmidt.]

yon Schmidt’s
terms.
Formation. peak eee eee
Later. Older.
Ordovician:
Borkholmdimestone st)! 2h oe sesso eee eto eee one F2 |Zone3
iyekholm limestone! ss: S252 ace eae oese eee eee it 2a
Wesenberg limestone: 535.5 ashe se we = eee eee ee eee 2
Jewe limestone: 20.0. 252i Secon see sis ssateee aeoee eeeeese 1b
Itfer limestone

CK ersish ales 2 2. ot eye ee eee SES eet ee ee
Echinospherites limestone
Orthoceratite (Vaginoceras) limestone
Glauconite limestone

Glauconite sandstone
Cambrian:

Dictyonemashaless 2 esa ek eo cee eee ee

Ungulite sandstone

Hee Uewecgun’

Blue clay and associated formations
Granite

Since the publication of the above table three divisions have been
recognized in formation D. The Jewe limestone has been restricted
to the lower division, D1; shaly strata succeed the limestone beds
of D1 and form the Kegel beds, D2, while D3, consisting of very
fossiliferous, thin bedded blue limestones and shales, forms the closing
member of the formation. The Orthoceratite limestone is often
cited simply as the Orthoceras limestone, and is so designated
throughout the present work.

The long-continued researches of the late Prof. F. von Schmidt
upon the Cambrian and Ordovician rocks of the Russian Baltic
provinces have resulted in such a detailed knowledge of the geology
that the stratigraphic section is now fairly well known. Pander,
von Kichwald, de Verneuil, Keyserling, Holm, and Lamansky have
contributed in a lesser degree to the stratigraphy, while, in addition
to these, von Schmidt, von Mickwitz, von Huene, Jaekel, Koken,
Pahlen, Dybowski, Wysogorski, and Bonnema have published re-
searches on the paleontology of the region. The paleontological
work of these authors has not, as a rule, been of a general nature,
although Eichwald’s Lethza Rossica is an important exception.
Thus, von Schmidt has elaborated the Ordovician trilobites in great
detail, while similarly Koken has monographed the gastropods,
Jaekel has studied the cystids, and Dybowski has described some -
of the monticuliporoids. More recently, Bonnema has published
upon the Ostracoda of the Kuckers shale.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 7

A number of authors have attempted correlations of the Russian
Cambrian and Ordovician rocks with the North American sequence,
but the ideas of most of these are reflected in the following table
adapted from Credner’s tables on pages 397 and 420 of his ‘‘Ele-
mente der Geologie:”’

Table of Cambrian and Ordovician strata.

[Adapted after Credner.]

Baltic Russia. North America.

Pent. borealis beds............--.--- Hudson River shale.
aT edS tens er et casn orem emone
Borkholm beds......-.

Lyckholm beds.....--

Wesenberg beds
Kegel and Jewe beds...-...-.-.-----
Brandsenielers eyes sascw ese ceee]

Utica shale.

Lower Silurian.

Black River limestone.

Trenton limestone.
Birdseye limestone.

Glauconite limestone and sands..... Chazy limestone.

Dictyonema shale............-- Sigoe Calciferous sandstone.

Obolus sandstone to the lowest con- |f Potsdam group.
Wanibriansesseeeeeses SlOMErALOM gee soaccseS sone ee aces \St. John (Acadian) group.

Blue clay to the top of the Olenellus | Georgia group (Olenellus series).
mickwitzi zone. Lowersandstone.

The basis for correlation of the Ordovician portion of this table is
rather difficult for the American student to determine. Probably
there is none other than an arrangement of the formations in the two
areas upon the supposition that corresponding strata are or should
be present in each.

Probably the best expression of opinion as to this correlation is
that given in the table on page 8, translated from Kayser’s tables,
pages 74 and 119 of his ‘‘ Lehrbuch der Geologie,” 1908, although this
offers the same objection. Here, however, the identification of the
strata ranging from the Orthoceras (Vaginaten) limestone to the
Wesenberg, with the Mohawkian, and the Lyckholm-Borkholm
series with the Cincinnatian, is more in line with the results brought
out from a study of the bryozoan faunas.

8 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

.

Table of Cambrian and Ordovician strata.

[Adapted after Kayser.]

European Russia. North America.
Upper Silurian....... Strata with smooth Pentamerus..... Oswegan (Clinton-Medina beds).
Borkholm and Lyckholm beds.....| Cincinnatian.
Wesenberg beds.........------------ Mohawkian.
Jewe, Itfer, Kuckers beds -......... Trenton limestone.
Echinospherites limestone......-.-- Black River-Birdseye limestone.
Lower Silurian (Or-
dovician).
Vaginaten limestone.............-.. Ch: :
Glauconite limestone ...........---- \ azy limestone. . .
Quebec group
of Canada.
Glauconite sand, Dictyograptus | Beekmantown lime
shale. stone.
Upper Cambrian or | Ungulite sandstone...............-- Potsdam sandstone.
Olenus- (Dicello-
cephalus) beds.
MiddlesCamprian: or=|22 32545 pe sae see ee St. John or Acadian group.

Paradoxides beds.

Lower Cambrian or | Fucoid sandstone, Blue clay, sand..| Georgia group.
Olenellus beds.

Von Schmidt’s descriptions of the stratigraphy of the Russian
Cambrian and Ordovician are contained in several papers, chief of
which is his ‘‘ Revision des Ostbaltischen Silurischen Trilobiten.’’
In 1882 a short description of these strata by the same author ap-
peared in the Quarterly Journal of the Geological Society of London,?
while still another article appeared in 1897, in the Guide of the Excur-
sions of the Seventh International Congress. From various sources,
but mainly from these several articles and from the collections in the
United States National Museum, I have compiled the following
notes on the stratigraphy of the region concerned in the present paper.
The stratigraphic relations of the rocks forming these notes are graph-
ically represented in the accompanying composite columnar section.

CAMBRIAN STRATA.

The sparing development of Cambrian rocks in the Russian Baltic
area is a striking feature. These rocks occur in a long, narrow belt
either paralleling or outcropping along the cliffs of the Gulf of Finland.
A lower blue clay and an upper sandstone deposit, usually not ex-
ceeding a combined thickness of about 100 feet, are the important

2On the Silurian (and Cambrian) Strata of the Baltic Province of Russia, as compared with those of

Scandinavia and the British Isles.
3 VII Congress Geol. Internat., 1897, pt. 12.

= =
a

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

Composite section of Cambrian-Early Silurian strata of Baltic Russia.

9

Period.

Silurian.

Ordovician.

Cana-
dian

Cambrian,

American
equiva: J epee tae rca au Description of strata.

abt Early Silurian limestone.

Sx 15° Formation F.

aS F 2. Borkholm limestone.

1) Massive. siliceous. white limestone.

EE F 1. Lyckholm limestone (upper part).

SS Gray to yellow argillaceous limestone with many

Re corals, Halysites, Calapcecia, Heliolites. etc.

BS 50! Middle Ordovician strata.

Derm F 1. Lyckholm limestone (lower part).

Magnesian limestone holding Maclurea, Subulites,

and other gastropods closely related to American
Trenton species.
Formation E. Wesenberg limestone.
30" Fossiliferous yellow shale and thin limestone inter-
bedded.
Formation D.
D 3. Wassalem beds.
ery fossiliiterous thin bedded blue limestone and
shale.
D 2. Kegel beds.
100° Shaly, fossiliferous limestone.
Ee D 1. Jewe beds.
& Siliceous limestone and shale holding many fossils,
g
ra
ia) Formation C.
> 30° C 3. Itfer limestone.
g Rather massive, siliceous limestone,
z © 2. Kuckers shale.
3 Unusually fossiliferous bituminous shales, with
B thin limestone bands.
Bi
fo 50’
nd
°
=
(22)
oo =| C 1. Echinospherites limestone.
= Thin bedded limestone with many trilobites and
> eystids.
=
°
a 50’
q
&
¥
8 ¢¢Obere Linsenschicht.” Zone of phosphatic pebbles.
ra Formation B.
=| B 8. Orthoceras (Vaginaten) limestone.
© 20° Rather massive gray limestone crowded with ceph-
LI alopods.
s «Untere Linsenschicht.” Zone of phosphatic pebbles.
=| B 2. Glauconite limestone.
Thin bedded, light green to reddish limestone,
sandy in the lower part.
40’
B 1. Glauconite sandstone. '
Unconsolidated green sand. Middle Ordovician
brachiopods in upper part.
10’ Dictyonema shales, A 3.

Dark brown to reddish bituminous clays holding
wg graptolites,particularly Dictyonema flabelliformis.
z 8 S 10’ Upper Cambrian, Ungulite sandstone, A 2.
mas Unconsolidated, yellow sandstone. Upper layers

crowded with Obolus apollinis.

g

ea 60’

a = Lower Cambrian, blue clay and associated strata, A 1.
nfossiliferous sandstone correlated with the Fu-
coid sandstone of Sweden.

Sandstone and clays holding Mesonacis mickwitzi.

g Plastic blue to green clay.
% 300”

)

o

a}

Lower sandstone with glauconite grains.

Pre-Cambrian granite.

10 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

formations, although locally other sediments are present. These two
predominating members gave rise to Schmidt’s divisions Al and A2.

Al. Blue clay and associated strata—This division, corresponding
to the Lower Cambrian of the general time scale, is composed mainly
of plastic, blue to green clay with sandy layers, resting directly-upon
pre-Cambrian gneiss and granite. In a well boring near St. Peters-
burg, a maximum thickness of 300 feet for these clays and associated
sandy layers was noted. Interbedded with the clay are sandy layers
which, in the lower part of the division, sometimes form a well-defined
bed of sandstone. Glauconite grains supposed to be casts of foramini-
fera, and doubtful remains of algz, are the only organic remains noted
in these lowest beds. Alternating clay and sandstone strata holding
large numbers of a very small Orthoceras-like fossil named Volbor-
thella, and fragments of stalks and arms, probably of cystids, termed
Platysolenites, succeed the more typical unfossiliferous blue clay
which forms the middle division of the formation. Other fossils of
this horizon are Mesonacis mickwitzi, two species of Scenella, meduse,
and the brachiopod, Mickwitzia moniifera. 'The meduse and the
last-mentioned species are known from the Lower Cambrian Eophy-
ton sandstone of Sweden. This fact, in connection with the occur-
rence of Mesonacis, fixes the age of the strata. Thirty to fifty feet of
unfossiliferous sandstone succeed this Russian equivalent of the
Eophyton sandstone, and upon stratigraphic grounds are correlated
with the Fucoid sandstone, the next higher member of the Lower
Cambrian in Sweden.

A2. Ungulite sandstone-——The Lower Cambrian is followed by an
unconsolidated yellow sandstone quite distinct from the underlying
Fucoid sandstone, but bearing a conglomerate composed of fragments
of the latter at its base. Phosphatic brachiopods, chiefly Obdolus
apollinis, are exceedingly abundant in the upper beds of this division
which has received the name of Ungulite sandstone on account of the
resemblance of this brachiopod’s muscular impression to the mark
of a horse’s hoof. The change of sedimentation and the basal con-
glomerate are indicative of a gap between the two formations, the
length of which can not be determined from the Russian section.
Comparison with the Swedish section places this Ungulite sand-
stone in the Upper Cambrian.*

Until the present time, the Cambrian strata of Russia, as well as
of other countries, have yielded no bryozoans, but the valves of a
number of specimens of Obolus from the Ungulite sandstone were
found to be incrusted with a ctenostomatous-like bryozoan described
here in later pages as Heteronema priscum.

1Prof. Schuchert has called my attention, too late for correction in tne text, to the fact that the
sandstone holding Obolus apollinis in Sweden is now referred to the basal Ordovician by the Swedish
geologists. If this correlation be correct, Heteronema priscum, the oldest-known bryozoan, is of more
Tecent age than hitherto supposed.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 11
ORDOVICIAN AND EARLY SILURIAN STRATA.

Very fossiliferous limestones and shales compose the greater portion
of the Russian Ordovician. The lowest strata are of dark colored
bituminous shales or plastic clays formerly regarded as of Cambrian
age, but, with later evidence, now assigned by some authors to the
lowest Ordovician. Following these beds is a glauconitic sandstone
and then come the more calcareous strata of Middle and Upper
Ordovician and Early Silurian age.

A$. Dictyonema beds.—The uppermost strata of Schmidt’s Cambrian
division A are dark brown to reddish bituminous shales and clay,
named for their characteristic fossil Dictyonema flabelliforme. These
strata, which are thin—indeed often absent—are correlated with
similar graptolite beds in Scandinavia, England, and elsewhere, and
are probably the only equivalent in Russia of the American Beekman-
town. Bryozoans are unknown in these strata.

B1. Glauconte sandstone —Resting upon the eroded Dictyonema
shale, or upon the lower Ungulite sandstone, are loose, more or less
unconsolidated green sands of variable thickness, although seldom
exceeding 10 feet. These strata have been considered as the base of
the Ordovician by von Schmidt, and in the latest edition of Kayser’s
‘‘Lehrbuch der Geologie, II, Geologische Formationskunde,” the
Dictyonema shale and the Glauconite sandstone are correlated with
the American Beekmantown. The unconformable position of the
Glauconite sandstone, and the presence of Middle Ordovician fossils
in its upper portion, are indicative that it is, in part at least, the initial
deposit of the succeeding limestones and shales.

A very detailed account of the strata and faunas of formation B has
been published by Lamansky* who recognizes two subdivisions in B1,
namely, a lower subdivision (Bla), with the phosphatic brachiopods,
Obolus siluricus and O. lingulxeformis, reminders of Cambrian time,
as the characteristic fossils, and an upper subdivision (B1b) holding
species of Megalaspis and of Orthis. These Cambrian-like brachiopods
are probably persistent forms with little stratigraphic value, but the
fauna occurring in the upper part of the greensand where the sand
grains are associated with dolomitic material and clay, is composed
of typical Middle Ordovician fossils. These species are listed in the
accompanying table, where it may be noted that brachiopods and
trilobites make up practically the entire list. Comparing this with
the preceding and succeeding groups of species, it becomes evident
that this is clearly not a derivative of the underlying Cambrian fauna.
The general association is much like the succeeding Ordovician faunas,
even though entire classes, such as the echinoderms, bryozoans, etc.,
are unrepresented. Gradually and without break the Glauconite

1 Die Aeltesten Silurischen Schichten Russlands (Etage B); Mem. Comite Geol., new ser., vol. 20, 1905,

92602°—Bull. 77—11——3

12 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

sandstone passes into the Glauconite limestone. The Glauconite
sandstone is apparently the record of a transgressing sea and its
several parts may therefore be of different ages. No bryozoans have
been found in division A38. Likewise none has been recorded from
division B1, although it is probable that some of the bryozoans listed
as occurring in B2 will also be found in the upper part of B1.

B2. Glauconite limestone——The presence of scattered glauconite
grains gives this limestone a light green tinge, although in places it is
of a reddish color with scattered greenish spots. The lowest beds are
sandy and are marked by the trilobite Megalaspis planilimbata
Angelin. The upper beds contain less glauconite and more shale.
Throughout gastropods are wanting and cephalopods are rare, but
trilobites, brachiopods, and bryozoans are not uncommon. Orthis
parva Pander, Porambonites reticulatus, P. altus, P. parvus, and
Clitambonites plana of the same author are the predominating brach-
iopods, while Dittopora claveformis Dybowski, D. annulata Eichwald,
Stictoporella gracilis (Hichwald), Dianulites fastigiatus Eichwald, D.
petropolitanus Dybowski, and Diplotrypa bicornis Eichwald, are the
most abundant of the described bryozoans.

Among the trilobites the genus Asaphus is well represented, and
species of Pterygometopus, Cheirurus, Lichas, and Ampyz are present.
The peculiar Bolboporites and the cystid genera Glyptocystites and
Echinoencrinites make their first appearance here.

A local movement at the end of this division gave rise to slight
erosion and to the formation in Esthonia of a thin zone of phosphatic
concretions known to the Russian geologist as the ‘‘Untere Linsen-
schichten.”’ West of Reval this band is absent and the Glauconite
limestone is followed by a sandstone phase of the overlying Orthoceras
limestone. The time break here is slight since the change in fauna is
not great.

In his studies Lamansky has recognized three subdivisions in B2 in
the government of St. Petersburg, and has described and listed their
faunas. The lowest subdivision (B2a) is composed of rather compact,
brightly colored limestone layers, rich in glauconite, and 5 to 10
inches thick. This zone, which altogether is only about 6 feet thick,
is known as the ‘‘horizon with Megalaspis planilimbata, M. limbata,
and Asaphus priscus,” and contains a fauna of which brachiopods
related to those of the underlying division Bib form a considerable
part. The strata of subdivision B2b are less compact, thinner lime-
stone layers with some shale, also amounting to about 6 feet in thick-
ness. Glauconite is less abundant in this zone, which receives its
designation from the characteristic trilobites Asaphus bréggerv and
Onchometopus volborthi.

Subdivision B2c, the ‘‘horizon with Asaphus lepidurus and Mega-
laspis gibbus,” is a gray, rather compact limestone 8 to 10 feet thick,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 13

holding less glauconite than either of the two preceding zones. As
the list shows, its fauna is closely related to the preceding as well as
the following strata.

Lamansky’s subdivisions of B2 and B3 were published after the
bryozoans studied were collected, so that Iam unable to place the
species in their proper zones.

B38. Orthoceras limestone.—This is a hard gray limestone varying
from 8 to 20 feet in thickness and crowded with individuals belonging
to several species of Orthoceras and Vaginoceras. The names Ortho-
ceratite, Orthoceras, Vaginoceras, or Vaginaten limestone have at
various times been applied to these rocks. Of these, I have selected
the name Orthoceras limestone for use in the present work. The
phosphatic concretionary layer at the base of the Orthoceras lime-
stone has already been mentioned, as has also the sandy phase of the
formation west of Reval. The fauna of the limestone is large and
includes a considerable number of cephalopods and gastropods, both
of these groups being very sparsely represented in the underlying
strata. The trilobites, however, lead in the number of species, with
the gastropods second in importance. Among the trilobites are
species of Asaphus, Ampyz, Megalaspis, Pterygometopus, and Cybele, as
well as many other genera. The gastropod genera Maclurea, Oxydis-
cus, Salpingostoma, Raphistoma, Bucania, Holopea, Clisiospira, and
Sinuites, well known in American deposits, are represented. The
brachiopods are more abundant than the gastropods in individuals
if not specifically, but the bryozoans are rather sparsely represented
and belong almost entirely to new species. Orthis, Clitambonites,
Porambonites, Plectambonites, and Rafinesquina are, as usual in these
deposits, the most important of the brachiopod genera.

The Orthoceras limestone has been studied carefully by Lamansky,
who recognizes three horizons, namely, B3a, the horizon holding
Asaphus expansus and A. lamansku, B3b, with Asaphus raniceps as
the characteristic fossil, and B3c, with Asaphus eichwaldi and
Piychopyge globifrons as horizon markers. The fauna of each of these
divisions is indicated in the lists on pages 19 to 25.

Following the Orthoceras limestone is another concretionary layer
known as the ‘‘Ober Linsenschicht.’”’? As many new species and a
decided change in lithology occur above this layer, the Russian geolo-
gists begin a new formation with the next horizon.

C1. Echinospherites limestone—Formation C is divided into two
well-defined members, namely, C1, a thin-bedded limestone named
after its characteristic fossil, a species of Echinospherites, followed by
C2, a bituminous shale deriving its name from exposures at Kuckers,
Esthonia. A third member, C3, a hard limestone 20 to 30 feet thick,
with numerous siliceous concretions, has been distinguished at a few
localities as the Itfer limestone. The most characteristic fossils of

14 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

the lowest division, C1, are a cephalopod, Orthoceras regulare Schlot-
heim, in the lower bed, Cla, and the concretionlike cystid Echino-
spherites distinguishing the upper part of the division, Clb. The
Echinospherites, EL. aurantium, is an especially noteworthy fossil on
account of its abundance and wide distribution. In America a species
of Echinospherites that I am unable to distinguish from EF. aurantiwm
is abundant at numerous localities in the Middle Ordovician rocks of
the Appalachian Valley and in the Kimmswick limestone of Black
River age in the Mississippi Valley.

Trilobites, gastropods, cystids, and brachiopods are as numerous in
the Echinospherites limestone as in the underlying Ordovician forma-
tions, and are represented by essentially the same genera. A bryozoan
fauna of 23 species, of which 11 are new, is described in the following
pages. Of these 23 species, 6 are characteristic fossils of the Black
River group of North America.

C2. Kuckers shale (Brandschiefer)—Faunally, the bituminous
shales and thin-bedded limestones making up the several members of
division C2 are closely related to the limestone of C1, although the
bryozoans and ostracods are developed in greater abundance both in
species and individuals. The thin bands of bituminous shales in C2
are often crowded with bifoliate and other delicate bryozoans (see
pl. 12), while the more solid zoaria of the trepostomatous Bryozoa
sometimes entirely compose the thin limestone layers. The strata of
this stage, which average from 30 to 50 feet in thickness, are well
shown at Kuckers, near Jewe, north of Lake Peipus, but the bryozoans
herein described from this formation come from other localities, prin-
cipally Baron Toll’s estate, near Jewe, Esthonia. Most of the Kuckers
fossils are probably the best preserved of all from the Russian Ordo-
vician strata, but they have not received the detailed study given to
the faunas of other Baltic formations.

A fauna of 46 species of Bryozoa was found in the collections from
the Kuckers, with 14 species common to Russia and the Black River
group of America.

The ostracode fauna has been carefully studied by Bonnema,! who
recognizes 34 species distributed among well-known American Middle
Ordovician genera, such as Primitiella, Tetradella, Ceratopsis, Cteno-
bolbina, Ulrichia, and Bollia. None of these is identified with Ameri-
can forms, although the species are in many instances closely allied.
Species closely related to these Kuckers forms occur in the underlying
and overlying Ordovician rocks in Russia, but they await description.

The trilobites are less numerous than in the underlying strata, but
their genera are essentially the same. The recorded brachiopods are
few in species, but this portion of the fauna has not received especial
attention.

1 Beitrag zur Kenntnis der Ostrakoden der Kuckersschen Schicht (C2), Mitteilungen aus dem Mineralo-
gisch-Geologischen Institut der Reichs-Universitat zu Gronongen, vol. 2, pt. 1, 1909,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 105)

C3. Itfer beds—tIn the vicinity of Itfer, north of Wesenberg, in
Esthonia, a hard limestone 20 to 30 feet in thickness, bearing siliceous
concretions, succeeds the shaly Kuckers zone and forms a passage
bed to the richly fossiliferous Jewe formation. Although the
described species are less numerous, the fauna of these Itfer beds is
essentially the same as in the other members of division C. Only one
bryozoan from these Itfer beds, Batostoma granulosum, has come to
my notice.

D1. Jewe limestone.—Very fossiliferous, impure limestone and shale,
averaging 100 feet in thickness, compose formation D, in which three
divisions are recognized by the Russian students, (1) a lower zone of
siliceous limestone and shales well exposed near Jewe and termed the
Jewe limestone, (2) more shaly strata known as the Kegel beds, and
(3) very fossiliferous thin-bedded, blue limestones and shales well
shown at Wassalem, whence they derive their name. The species of
these three divisions are much alike, and likewise are quite similar
to many of the forms in formation C.

The cystids, trilobites, and gastropods are the only groups of D1
which have hitherto received detailed study. The collections of
bryozoans from the Jewe limestone were not very extensive, but they
showed 29 species, of which 8 are identical with American Middle
Ordovician forms.

D2. Kegel beds—The shaly strata making up this division have
received probably less study than the Jewe limestone, judging from
the list of described species, but from a few samples before me, I should
judge the fauna to be a large and varied one. A fragment of lime-
stone less than half a cubic inch in size, preserved only for a trilobite
head upon it, was found upon thin sectioning to contain no less than
9 species of Bryozoa. This fragment and a few additional specimens
afforded the 12 species of Kegel bryozoans noted in this paper.

D3. Wassalem beds.—The thin-bedded, blue, argillaceous limestone
and shale of this division is the most fossiliferous of all the Russian for-
mations as far as bryozoans are concerned. Some of the layers are
literally one mass of these organisms, as is evident from plate 13,
which represents the surface of one of the thin limestone layers.

The preservation of the specimens from D3 is most beautiful on the
exterior, but the interior is sometimes destroyed by a form of dolomi-
tization. Similar conditions of preservation prevail in the Ordovician
(Decorah shales) bryozoans of Minnesota, and the lithologic resem-
blance of the strata comprising the Russian division D3 to these
American beds is most striking. This lithologic similarity is borne
out in the bryozoan faunas of the two areas, for of the 43 species now
known from the Wassalem, 26 are American Middle Ordovician forms.
A glance over the table on page 50, giving the list of species with their
distribution, will show the large percentage of typical Black River

16 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

species. The large number of species determined from the Wassalem
beds was made possible by the study of the Mickwitz collection
which was especially rich in bryozoans from this division.

E. Wesenberg limestone——Succeeding the Jewe limestone is an
equally fossiliferous and widespread formation of thin limestone and
shale named from its occurrence at Wesenberg. Both the limestones
and shales of the Wesenberg are of a yellowish color and seldom
-exceed 30 feet in thickness.

The fauna of the Wesenberg limestone is strikingly like that of the
lowest Trenton strata of the United States, classed under the names
Clitambonites, Nematopora, and Fusispira beds. Several species of
Clitambonites occur in the Wesenberg, and in America the earliest
occurrence of the genus is in the bed named for it. At least one of
the species in the two areas is not very dissimilar. Other species of
brachiopods which are common to the two beds, or are represented
by closely related forms, are Dalmanella testudinaria (small variety),
Plectorthis plicatella, Plectambonites sericeus (variety), Strophomena cir.
scofieldi, and Rafinesquina cfr. deltordea.

The Russian Wesenberg pelecypods have not been studied in detail,
but specimens before me, in a few cases, resemble American forms.
The gastropods of both areas are well known and show some similarity;
thus the large Pleurotomaria insignis Eichwald is certainly the same
as Hormotoma major Hall, from the earliest Trenton of Missouri and
Minnesota, and the Russian examples of Maclurea neretoides Goldfuss
are close to American species. Among the corals a Protarea and a
Streptelasma like S. profwndum, are represented in each area. Con-
siderable resemblance is shown in the bryozoans, indeed, a slab of the
Wesenberg limestone covered with numerous examples of Hallopora
goodhuensis, Eridotrypa edilis and variety minor, Pachydictya elegans,
and with the incrusting Corynotrypa wmflata, resembles very greatly
material from the Clitambonites bed.

F.. Lyckholm and Borkholm.—The uppermost strata of the Baltic
region assigned to the Ordovician by authors, comprise gray to white
limestones attaining a thickness of 65 feet and restricted to Esthonia
and the islands of Worms and Dago. Schmidt recognized two zones
in this formation, which he designated F, a lower Lyckholm zone
(F1), of gray and yellow, sometimes dolomitic limestone, and an
upper Borkholm zone (F2), of hard, white siliceous limestone. The
faunas of the Borkholm and of the upper part of the Lyckholm are
essentially the same and upon their evidence no necessity exists for
recognizing two zones. The bryozoans, ostracods, and corals of
these beds are of genera and often of species characteristic of the
- Richmond formation of America. Among the corals, for example, are
species of Tetradvum, Favosites, Heliolites, Plasmopora, and Calapecia,
an assemblage of forms that, on the whole, is distinctly Silurian in

EARLY PALEOZOICG BRYOZOA OF THE BALTIC PROVINCES. 17

character. A similar coral zone is widespread in the Richmond
group of western North America, where it follows argillaceous and
magnesian rocks of Galena-Trenton age.

. Although there is no direct evidence in published work, it seems
probable that a similar Galena-Trenton zone underlies the coral beds
of the Lyckholm. In a fauna collected from the lower Lyckholm by
Prof. Schuchert, every species is closely related to forms from the
typical Galena of the Mississippi Valley, and elsewhere in North
America. At many places to the north, west, and east of Minnesota
the Galena fauna is followed directly by the coral bed of the Rich-
mond. In America the lithology of these Galena-Trenton and
Richmond strata is so similar that both have been uniformly included
in a single magnesian limestone formation. Without the evidence
of the fossils the presence of a great time break in this formation
might not be suspected. The bryozoans of the lower Lyckholm
are, like those of the American Galena, distinctly Trenton in character,
while those of the upper Lyckholm and Borkholm include char-
acteristic American Richmond species.

These latter strata also contain small forms of an undoubted
Atrypa, Leptena rhomboidalis, a typical Streptis, a Stricklandinia,
and other brachiopods of Silurian affinities. Of the 19 species of
Bryozoa identified in the Lyckholm, 5 can not be considered in
correlation, as they are here described for the first time. Five
additional species of the list either are known to come from the
lower beds of the formation or are long ranged geologically. Of
the remaining 9, Corynotrypa abrupta Bassler, Nematopora fragilis
Ulrich, and Anaphragma mirabile Ulrich and Bassler are charac-
teristic Richmond fossils, while Corynotrypa dissimilis (Vine),
Pachydictya bifurcata (Hall), Glauconome plumula Wiman, Orbigny-
ella expansa baltica, new variety, and Hallopora elegantula (Hall)
are either identical or closely related to typical Silurian bryozoans.
Thus on the evidence of the bryozoans the upper Lyckholm is of
early Silurian age.

The bryozoan fauna of the Borkholm is clearly of Silurian age,
since practically every species is of a well-known Richmond or early
Niagaran type. The list of the strictly Borkholm species, with
their occurrence in America or their American representative added
in parentheses, follows:

List of Borkholm Bryozoa.

Corynotrypa dissimilis (Vine) (Niagaran of America.)
Ptilodictya flabellata Kichwald (Pittlodictya expansa Hall).
Ptilodictya gladiola Billings (Richmond of America).
Pachydictya bifurcata (Hall) (Niagaran of America).
Sceptropora facula Ulrich (Richmond of America).

18 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Nematopora lineata (Billings) (Richmond of America).

Glauconome plumula Wiman (Glauconome sp., Niagaran of America.)

Glauconome strigosa (Billings) (Richmond of America).

Lichenalia concentrica Hall (Niagaran of America).

Hallopora elegantula (Hall) (Niagaran of America).

Chasmatopora tenella (Eichwald) (Chasmatopora angulata Hall, in early Niagaran
of America).

Fenestella striolata Eichwald (Fenestella granulosa Whitfield, Richmond of America).

Protocrisina exigua Ulrich (Richmond of America).

Phenopora ensiformis (Hall) (Early Niagaran of America).

Pseudohornera orosa (Wiman).

Tn the following table I have given the figures showing the total
number of bryozoan species in the various Russian formations in
the first column and the number of American species common to
the two areas in the second. With scarcely an exception, all of
these American Middle Ordovician species are from the Black River
eroup and the earliest Trenton, while the American species, found
also in the upper Lyckholm and Borkholm, are all of early Silurian

types.

Summary of Baltic and American Ordovician and Early Silurian Bryozoa.

Number

Total num-| ©! Species
Formation. ber of Bal- common ite

tic species. and Baltic

areas.
pes Sl he UE ee OE es ee ee
Early Silurian.
Borkcholmblimestone) G2) meeeeer eee ne eee eee cease ee Peer ae eee eae Sere eet 15 10
Lyckholm limestone (F1) (including the lower part, of possible Middle Ordovi-
GEER) Yue roueacaeas ene sessosSesedesrerbossseeacHas ssacesaseeEebosoSeoseoccce 19 10
Middle Ordovician.

Wesenherg limestone (E)...-...-..------------------ +--+ 22-2222 renee eee 24 10
Titeseallersa | ose (CDE)) 55 Suenos ass secsse 5 cocoace sos coo Ssonocoscocsaasoszacceeansas: 43 26
Kegel beds (D2)....-.-..---------------- 2-2-0222 eee eee eee 12 1
Nawellimestome GD) peisee eee seers ena oreeic sees eer nee e eee EEE eee 29 8
iititsre) os (C8) aise pooStonesenboeue sees ebesnoosS ooseoss=csusdss5sas0s56e55ss5eoce 1 0
Kickers shale (C2) eee ae oe se esate = leaned ole elal= ee ale ele l= aie odio eal 46 11
Echinospherites limestone (C1)......-..---------------- +--+ --++-+2--- 2-22-22 23 6
@rthoceras limestone (B38)... ------------ 22-2 22-22 ow oe ee 14 2
Glauconite limestone (B2).......-.-------------- +--+ 2-22 - eee eee 11 2

Summarizing the foregoing remarks, it would appear, from a
study of the Bryozoa, at least, that the Russian Baltic section is
far from complete; indeed, is composed of fragments only of the
great North American sequence. Thus the entire Cambrian is repre-
sented by only a few hundred feet of strata, and all of the Canadian
by the thin Dictyonema beds, probably of Beekmantown agp.
Beginning with the invading Glauconite sandstone and continuing
until the close of the Wesenberg, the faunas are uniformly of Middle
Ordovician age and represent the Black River and earliest Trenton
formations of the American section. A later Trenton horizon is
probably represented in the lower Lyckholm. The remainder of

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 19

the Lyckholm and all of the Borkholm are, in American terms, of
Richmond (earliest Silurian) age.

PALEONTOLOGY OF THE BALTIC AREA.

Although it was my intention to treat only of the Russian Ordo-
vician bryozoan faunas, it became necessary, in order to get an
idea of- the associated forms, to compile lists showing the distribu-
tion of the other groups of organisms. As such lists of these Russian
species have never been assembled in one publication, they are
reproduced herewith for the benefit of future workers on these faunas.
These lists, however, do not contain all the species that have been
named, for Hichwald especially has described a large number which
are not included because they have never been assigned to any
horizon other than the ‘‘calcaire 4 Orthoceratites,’’ which includes
all of the formations from -B to F, inclusive. Similar lists of the
Ordovician fossils of the upper Mississippi Valley are given in part 2,
volume 3, of the Minnesota Geological Survey, to which the student
is referred when making comparisons between the two areas. The
following lists, however, do not include the Bryozoa, which are
tabulated on a later page.

MISCELLANEOUS. Petraia darcoceras Dybowski, F1.

Petraia silurice Dybowski, F1.
Pholidophyllum tubulatum Schlotheim, F2.
Proheliolites dubitus Schmidt, F1.

Propora bacillifera Lamansky, F1, F2.
Propora cancellata Lamansky, F2.
Propora conferta Edwards and Haime, ?F1, F2.
Propora tubulata Edwards and Haime, F1.
Protarea vetusta Hall, F1.

Protarea sp., E.

Streptelasma cfr. profundum Hall, E.
Streptelasma corniculum Hall, F1.
Streptelasma elongatum Phillips, F2.
Streptelasma europxum Roemer, F1, F2.

Astylospongia globosa Hichwald, B3.
Aulocopella cepa (Roemer) F1.
Aulocopium aurantium Oswald, F1, ?F2.
Cyclocrinus spasski Kichwald, D3, F1.
Mastopora concava Hichwald, D1, BE.
Phyllograptus sp., B3.
Receptaculites eichwaldi Schmidt, D1.
Receptaculites orbis Hichwald, C1.
Siphonia cylindrica Eichwald, B1.
Solenopora spongioides Dybowski, D3, D1, C1, F1.
(=S. compacta Billings).
Stromatopora mammillata Schmidt, F2.

ANTHOZOA. Calapeécia cribriformis Nicholson, F2.
Syringophyllum organon Linnzeus, F2.
Acantholithus asteriscus Roemer, F1, F2. Tetradium sp., F2.
Alveolites? hexagona Schmidt, Fi. ACHR.
Coccoseris megastoma var. minor Lamansky, F1.
Coccoseris micraster Lamansky, F1. A steroblastus foveolatus (Hichwald), B3.
Coccoseris microporus Hichwald, F2. A steroblastus sublevis Jaekel, B2a.
Coccoseris ungerni Hichwald, F1. A steroblastus tuberculatus Schmidt, B3.
Coelophyllum amalloides Dybowski, F2. A steroblastus volbortht Schmidt, B3.
Columnaria fascicula Kutorga, F1, F2. A sterocrinus munsteri Eichwald, B2a.
Cyathophyllum middendorfii Dybowski, F2. Blastoidocrinus sp., B3.
Endophyllum contortiseptatum var. precursor Weis- | Bolboporites sp., B3a, B3b.
serm, F2. Bolboporites semiglobosa Pander, B2a, B2b, B2c.
Favosites asper d’Orbigny, F2. Bolboporites triangularis Pander, B2a, B2b, B2c.
Halysites catenularius Linneeus, F1, F2. Bolboporites triangularis var. wncinata Pander, B2a,
Halysites escharoides Lamarck, F1, F2. B2b, B2e.
Halysites parallela Schmidt, F1, F2. Caryocystites aranea Schlotheim, C1.
Halysites undulata Kiaer, F1, F2. Caryocystites balticus (Kichwald), C1.
Heliolites hirsutus Lamansky, F1. Chirocrinus atavus Jaekel, B3.
Heliolites interstinctus, Linneeus, F1. Chirocrinus degener Jaekel, B3, C1.
Heliolites parvistella Roemer, F1. Chirocrinus giganteus Leuchtenberg, B2a, B2b.

Labechia conferta Edwards and Haime, F1. Chirocrinus granulatus Iaekel, C2.

20

Chirocrinus insignis Jaekel, B3.

Chirocrinus ornatus Hichwald, B3.

Chirocrinus penniger (Eichwald), B3.

Chirocrinus radiatus Jaekel, B3.

Chirocrinus striatus Jaekel, B3.

Chirocrinus sculptus Schmidt, B3.

Chirocrinus volborthi (Schmidt), B3.

Cryptocrinus levis Pander, C1.

Cyathocrinus? exilis Hichwald, B2b, B2e.

Cyathocystis plautine Schmidt, C1.

Cyathocystis rhizophora Schmidt, D3.

Cystoblastus kokeni Jaekel, C2.

Cystoblastus leuchtenbergi Volborth, C1.

Dactylocystis mickwitzi Jaekel, D3, E.

Dactylocystis schmidti Jaekel, D3.

Echinoencrinites angulosus Pander, B2a, B2b, B2c,
B3.

Echinoencrinites angulosus var. compta Jaeke!, B3.

Echinoencrinites angulosus var. quadrata Jaekel, B3.

Echinoencrinites levigatus Jaekel, Bsa.

Echinoencrinites lahuseni Jaekel, B3.

Echinoencrinites reticulatus Jaekel, B2c, B3.

Echinoencrinites senckenbergi Muller, B3a.

Echinoencrinites senckenbergi var. interlevigata
Jaekel, B3a.

Echinoencrinites striatus (Pander), B3.

Echinospherites aurantiwm (Gylenhahl), C1, C2, C3,
D1, D3.

Echinospherites difformis Jaekel, C3, D3.

Echinospherites pirum Jaekel, C3, D3.

Erinocystis angulata Jaekel, B3.

Erinocystis sculpta Jaekel, B3.

Erinocystis volborthi Jaekel, B3.

Glaphyrocystis compressa Jaekel, F1.

Glaphyrocystis wohrmanni Jaekel, F1.

Glyptocystites sp., B3a.

Glyptocystites giganteus Linnzeus, B2c.

Glyptosphzrites leuchtenbergi Angelin, B3.

Haplocrinus? monile Kichwald, B2a, B2b, B2c.

Hemicosmites extraneus Hichwald, D3.

Hemicosmites grandis Jaekel, F 1.

Hemicosmites levis Jaekel, C1.

Hemicosmites malum Pander, Cl.

Hemicosmites pocillum Jaekel, D3.

Hemicosmites pulcherrimus Jaekel, D3.

Hemicosmites rudis Jaekel, D3.

Hemicosmites tricornis Jaekel, F2.

Hemicosmites verrucosus Kichwald, F1.

Hybocrinus dipentus Lindstrom, C1, C2.

Mesocystis pusyrewskii Hofiman, B2b, B3.

Pentacrinus? antiquus Eichwald, B2c.

Protocrinites fragum HKichwald, C1.

Scoliocystis pumila (Hichwald), B3.

Scoliocystis thersites Jaekel, B3.

A number of other species of echinoderms, espe-
cially crinoids, were described by Eichwald, but
almost all of them require restudy to determine
their exact position in the section. Among these
was the first echinoid, Bothriocidaris globulus
Eichwald.

BRACHIOPODA.

Atrypa imbricata Sowerby, F1, F2.
Atrypa marginalis Dalman, F2.
Atrypa cf. nodostriata Hall, F2.
Atrypa undifera Schmidt, F2.
Aulacomerella angusta Huene, F1.

BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Aulacomerella macroderma (Eichwald), F1.
Christiania oblonga (Pander), C1.
Clitambonites adscendens (Pander), B3b, B3e, C1.
Clitambonites anomala (Schlotheim), D, E.
Clitambonites concava (Pahlen), B3b, B3c.
Clitambonites emarginata (Pahlen), E.
Clitambonites hemipronites (de Buch), C1.
Clitambonites inflera (Pander), B3a, B3b, B3c, C1.
Clitambonites ingrica (Pahlen), B2a, B2b, B2c.
Clitambonites marginata (Pahlen), C2.
Clitambonites ornata (Verneuil), B3b, B3c.
Clitambonites plana (Pander), B2a, B2b, B2c.
Clitambonites plana var. alia (Pahlen), B2a, B2b.
Clitambonites plana var. excavata (Pahlen), B2e.
Clitambonites pyramidalis (Pahlen), C2.
Clitambonites pyron (Eichwald), B3b, B3c, C1, D.
Clitambonites radians (Eichwald), B3a.
Clitambonites sinwata (Pahlen), F1, F2.
Clitambonites squamata (Pahlen), C2.
Clitambonites trigonula (Kichwald), B3b.
Clitambonites verneuili (Hichwald), F1, F2.
Clitambonites wesenbergensis (Pahlen), E.
Craniella? papillifera Huene, F1.

Dalmanella testudinaria (Dalman), C1, D, E.
Dinobolus schmidti Davidson, F1.

Discina gibba Lamarck, F2.

Eleutherocrania gibberosa Huene, F1, F2.
Leptena imbrex Pander, B3a, B3b.

Leptzna nefedjewi Kichwald, B3a, B3b, B3e.
Leptzena rhomboidalis (Wilckens), F2.
Lepizna schmidti Tornquist, F1, F2.

Lingula birugata Kutorga, B3a, B3b, B3c.
Lingula lata Pander, B3e.

Lingula longissima Pander, B2b, B2c.
Lingula quadraia Eichwald, F1.

Lycophoria nucella Dalman, B3a, B3b, B3e.
Obolus siluricus Eichwald, B1.

Obolus linguleformis Mickwitz, B1.

Orthis abcissa Pander, B2a, Blb.

Orthis actoniz Sowerby, F1, F2.

Orthis bocki Lamansky, B1b.

Orthis callactis Dalman, B3a, F1.

Orthis calligrama Dalman, B3a, B3b, Bae, C2.
Orthis christianiz Kjerulf, B1b.

Orthis concinna Lamansky, F1.

Orthis elegantula mut. estona Wysogorski, F1.
Orthis extensa Pander, B3a, B3b.

Orthis flabellulum Sowerby, F1.

Orthis incurvata Lamansky, B1b.

Orthis lyckholmensis W ysogorski, F1.

Orthis obtusa Pander, B2b, B2c.

Orthis obtusa var. eminens Verneuil, B3a.
Orthis orthambonites Verneuil, B2a, B2c.
Orthis oswaldi von Buch, F1, F2.

Orthis parva Pander, B2a, B2b, B2c.

Orthis parva Pander, var., B3a, B3b.

Orthis parvula Lamansky, B1b.

Orthis recta Pander, B1b.

Orthis sadewitzensis Roemer, F1, F2.

Orthis schmidti W ysogorski, B2a.

Orthis solaris von Buch, F1.

Orthis striata Pander, B1b.

Orthis tetragona Pander, B2a, Bib.

Orthis tetragona var. lata Pander, B1b.

Orthis transversa Pander, B1b.

Orihis transversa var. latestriata Lamansky, B1b.
Orthis vespertilio Sowerby, F1.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

Phithedra rivulosa Kutorga, B3c.
Platystrophia biforata (Schlotheim), E.
Platystrophia biforata lynx Hichwald, F1, F2.
Platystrophia bifurcata (Eichwald), C1.
Platystrophia chama (von Buch), C2.
Plectambonites sericeus (Sowerby), E, F2.
Plecitambonites transversa (Pander), C1.
Plectella eminens Lamansky, Bib.
Plectella extensa Lamansky, Bib.
Plectella gracilis, Lamansky, B1b.
Plectella media Lamansky, B1b.
Plectella obtusa Lamansky, Bib.
Plectella semiovata Lamansky, Bib.
Pleciella unciniata Lamansky, B1b.
Pleciorthis plicatella (Hall), E.
Porambonites equirostris Schlotheim, C1.
Porambonites altus Pander, B2a, B2b, B2c.
Porambonites broggert Lamansky, Bib.
Porambonites deformata Eichwald, C1.
Porambonites gigas Hichwald, E, Fl. ~*
Porambonites intercedens Pander, B3a, B3b, B3ec.
Porambonites parvus Pander, B2a, B2b, B2c.
Porambonites planus Pander, B2a, B2b, B2c.
Porambonites reticulatus Pander, B2b, B2c.
Porambonites teretior (Kichwald), C2.
Porambonites triangularis Pander, B2a, B2b, B2c.
Pseudocrania antiquissima Eichwald, B3c.
Pseudocrania cranoides Huene, F1, F2.
Pseudocrania depressa Kichwald, D.
Pseudocrania petropolitana Pander, B2b, B2c.
Pseudocrania planissima Hichwald, C1, C2.
Pseudocrania scutella Huene, B3a, B3b, B3c.
Pseudometoptoma concentricum Huene, F1, F2.
Pseudometoptoma curvatum Huene, F1.
Pseudometoptoma monopleurum Huene, Fi, F2.
Pseudometoptoma siluricum Eichwald, B3c.
Rafinesquina imbrez (Pander), C1.
Siphonotreta unguiculata Hichwald, B3a, B3b, Cl,
C2.
Siphonotreta verrucosa Eichwald, B2b, B2c.
Streptis sp., F2.
Stricklandinia sp., F2.
Strophomena assmussi Verneuil, D, F1.
Strophomene deltoidea Conrad, E, F1.
Strophomena exrpansa Sowerby, F2.
Strophomena jentzschi Gagel, B3a, B3b, B3c.
Strophomena luna Tornquist, F1, F2.
Strophomena rugosa Blainville, D, E.
Strophomena near scofieldi Winchell and Schuchert,
E.
Strophomena semipartita Roemer, F1.
Strophomena tenuistriata Sowerby, F1, F2.
Triplecia dorsata (Hisinger), C2.
Triplecia insularis Eichwald, F1.

CEPHALOPODA.

Cyrtoceras angulosum Schmidt, F1.

Cyrioceras archiaci Verneuil, B3c.

Cyrtoceras sphinz Schmidt, F1.

Discoceras antiquissimum (Eichwald) F1, F2.
Endoceras commune Wahlenberg, B3c.
Endoceras duplez Schlotheim, B3hb, B3c.
Endoceras hasta Eichwald, F1.

Endoceras trochleare Hisinger, B3a, B3b, B3c.
Endoceras vaginatum Schlotheim, B3a, B3b, B3c.
E£stonioceras ariense Schmidt, B3c.
Estonioceras imperfectum Schlotheim, B3ec.

21

Estonioceras perforatum Schroeder, B3c.
Gomphoceras sp., E.

Gomphoceras litwus Hisinger, C1.
Gomphoceras odini Verneuil, C1.
Orthoceras arcuolyratum Hall, F1.
Orthoceras atavus Broégger, B1b.
Orthoceras calamitewm Portlock, F2.
Orthoceras cuneolus Eichwald, F1.
Orthoceras exaltatum Eichwald, F1.
Orthoceras fenestratum Eichwald, F1.
Orthoceras ibex Eichwald, F1.
Orthoceras regulare Schlotheim, €1.
Planctoceras falcatum Schlotheim, B3e.

PTEROPODA.
Conularia sp., B3a.
Conularia buchi Kichwald, B2c.
Conularia quadrisulcata Leuchtenberg, B3b.
Conularia ef. trentonensis Hall, F1.
Hyolithes acutus Eichwald, B3c.
Hyolithes striatus Eichwald, C2.
Tentaculites sp., E.
Tentaculites anglicus Salter, F1.
Tentaculites annulatus Schlotheim, F2.

PELECYPODA.

Ambonychia radiata Hall, F1, F2.
Modiola devera Eichwald, F1.
Modiola incrassata Eichwald, F1.

Twenty-eight species of Ordovician peleeypods
belonging to Avicula, Pterinea, Modiolopsis,
Cypricardia, Grammysia, and other genera, are
described by Eichwald, but arenotmore definitely
located geologically.

GASTROPODA.

Bucania contorta Hichwald C1, D1, D2, Cl, F1.

Bucania cornu Koken, F1.

Bucania crassa Koken, F 1.

Bucania crassiuscula Koken, D1, D2.

Bucania cycloides Koken, D2.

Bucania cycloides Koken, mut., F1.

Bucania radiata (Kichwald), C1, C2, C3, D1, D2,
E, Fl.

Bucania radiata (Kichwald), mut. macer Koken, B3.

Bucania salpinz Koken, C1.

Bucaniella conspicua Koken.

Bucaniella decurrens (Hichwald), B3.

Bucaniellajugata Koken, Cl.

Bucaniellajugata Koken, mut., C2.

Bucaniella lateralis Koken, D1, D2.

Bucaniella lineata Koken, D1, D2.

Bucaniella obtusangula Koken, C1, D1, D2.

Bucaniella revaliensis Koken, B3.

Bucaniella rudicosiata Koken, C1.

Bucaniella silurica (Eichwald), B3.

Bucaniella undata Koken, C1.

Clisiospira ingrica Koken, B3.

Cyclonema lineatum Koken, D2.

Cymbularia aequalis Koken; F1.

Cymbularia angusta Koken, C1.

Cymbularia cultrijugata Koken, D1, D2.

Cymbularia galeata Koken, C1, C2.

Cyrtolites grandis Koken, C1.

Carinaropsis rostrata (Hichwald), Ci, D1, D2, ?7E.

Carinaropsis rostrata (Hichwald), mut., B3.

Eccyliopterus centrifugus Koken, C1.

22 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Eccyliopterus increscens (Eichwald), C1.
Eccyliopterus increscens (Eichwald), mut., C2.
Eccyliopterus tolli Koken, C2.

Ectomaria kirnaensis Koken, F1-.

Ectomaria nieszkowskii Koken, F2.

? Eunema piersalense Koken, F1.

? Eunema rupestre (Kichwald), F1, F2.

? Eunema rupestre var. sulcifera Kichwald, F1.
?£Lunema schmidti Koken, F1, F2.
Euomphalus carinifera Koken, F1.

Euomphalus devexus Hichwald, C1, C2, C3, D1, D2.

Euomphalus dimidiata Koken, F2.
Euomphalus gradatus Koken, F1, F2.
Euomphalus helocoides Koken, F2.
Euomphalus laminosus Koken, F1.
Euomphalus turbiniformis Koken, D1, D2.
Gonionema angulosum Koken, C1.
Gonionema angulosum var. cingulata Koken, B3.
Gonionema gradatum Koken, B3.
Gonionema reticulatum Koken, B3.
Helicotoma superba Koken, F2.

Holopea ampullacea Hichwald, F1.

Holopea ampullacea var. coronata Koken, F1.
? Holopea eichwaldi Koken, B3, Cl.

Holopea nitida Koken, B3.

Isospira bucanioides Koken, D1, F1.
Lytospira anguina Koken, C3.

Lytospira evolvens Koken, C1.

Lytospira tubicina Koken, B3.

Lytospira valida Koken, F1.

Maclurea dilatata Koken, B3.

Maclurea heliz Richwald, B3, Bae.
Maclurea neritoides Eichwald, F1.
Maclurea planorbis Koken, B3.
Murchisonia exilis Fichwald, H, F1.
Murchisonia insignis Kichwald, F1.
Murchisonia insignis Hichwald, mut., E.
Murchisonia meyendorfi Koken, F2.
Murchisonia scrobiculata Koken, F1.
Murchisonia spectabilis (Schmidt), F1.
Oxydiscus ingricus (Verneuil), B3.
Oxydiscus planissimus (Kichwald), D2.
Paleacmea constricia (Eichwald), C1.
Platyceras constrictum Koken, D1, D2.
Platyceras meyendorfi Koken, D2.
Pleurotomaria baltica Eichwald, E.
Pleurotomaria chamzconus Koken, F1.
Pleurotomaria elliptica (Hisinger), B3, C1, C2, K.
Pleurotomaria elliptica (Hisinger), mut., C3.
Pleurotomaria inflata Koken, C1, C2, B3.
Pleurotomaria lahuseni Koken, D1.
Pleurotomaria lenticularis Hall, EK.
Pleurotomaria maritima Koken, C1.
Pleurotomaria nodulosa Schmidt, F1.
Pleurotomaria notabilis Hichwald, F1.
Pleurotomaria notabilis Eichwald, mut., C3.
Pleurotomaria notabilis Eichwald, mut., C2.
Pleurotomaria notabilis Kichwald, mut., D1, D2.
Pleurotomaria notlingi Koken, F1.
Pleurotomaria numismalis Koken, F1.
Pleurotomaria plicifera Eichwald, F1.
Pleurotomaria rossica Koken, C1, C2.
Pleurotomaria rotelloidea Koken, F1.
Pleurotomaria rudissima Koken, B3.
?Polytropis cingulata Koken, B3, Cl.
Pollicina corniculum EKichwald, B3.
Pollicina crassitesta Koken, B3.

Pycnomphalus borkholmensis Koken, F1, F2.
Raphistoma acutangulum Koken, C2.
Raphistoma acutangulum Koken, mut., D1.
Raphistoma applanatum Koken, B3.
Raphistoma lineolus (Eichwald), B38, C1.
Raphistoma marginale Koken, C1.
Raphistoma marginale Koken, mut., C2.
Raphistoma marginale Koken, mut., C3.
Raphistoma marginale Koken, mut., D1, D2.
Raphisioma mutans Koken, C1.

Raphistoma qualteriatum Schlotheim, B3, B3a, B3b,

B38e.
Raphistoma scalare Koken, C1.
Raphistoma scalitoides Koken, B3, ?C1.
Raphistoma wesenbergense Koken, E.
Salpingostoma carrolense Koken, C1.
Salpingostoma compressum (EKichwald), C2.
Salpingostoma dilatatum (Eichwald), F1.
Salpingostoma locator (Hichwald), B3, B3e.
Salpingostoma megalostoma (Kichwald), Cl.
Sinuites sp., B3a.
Sinuites sp., B3e.
Sinuites sp., B3b.
Sinuites bilobatus Sowerby, F1.
Sinuites bilobatus Sowerby, mut., D1, D2.
Sinuites bilobatus Sowerby, mut., E.
Sinuites nanus Wichwald, B3, C1.
Sinuites naviculoides Koken, B3.
Sinuites rugulosus Koken, .B3, C1.
Sinuites rugulosus Koken, mut., C2.
Subulites amphora Kichwald, D1, D2.
Subulites bullatus Koken, F1.
Subulites gigas Kichwald, F1.
Subulites inflatus Hichwald, E, F1.
Subulites peregrinus (Schlotheim), C1, C2.
Subulites subula Koken, HE, F1.
Subulites subula var. revaliensis Koken, C1, C3.
Subulites wesenbergensis Koken, E.
Temnodiscus accola Koken, C1, C3, D1, D2.
Temnodiscus secans Koken, B3.
Trochonema minor Koken, F2.
Trochonema panderi Koken, F2.
Trochonema peraltum Koken, F2.
Tryblidium esthonum Koken, F2.
Tryblidium lindstromi Koken, F2.
Turbo balticus Koken, C1, D1, D2.
Worthenia aista Koken, F1.
Worthenia borkholmensis Koken, F2.
Worthenia esthona Koken, F1.
Worthenia esthona Koken, mut., D1, D2.
Worthenia esthona Koken, mut., C2, C3.
Worthenia initialis Koken, B3.
Worthenia mickwitzi Koken, C1, C2, C3, D1, D2.
Worthenia mickwitzi Koken, mut., E.

Worthenia silurica (Hichwald), C1, C2, C3, B3, D1,

D2, F1.
Worthenia tolli Koken F2.
Worthenia vermetus Koken, F1.

OSTRACODA.

Bollia granulosa Krause, C2.

Bollia minor var. kuckersiana Bonnema, C2.
Bollia minor var. robusta Bonnema, C2.
Bollia ornata (Krause), C2.

Bollia ornata var. latimarginata Bonnema, C2.
Ceratopsis cornuta (Krause), C2.

Ceratopsis schmidti Bonnema, C2.

A,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 23

Ctenobolbina carinata (Krause), C2.

Ctenobolbina kuckersiana Bonnema, C2.

Ctenobolbina (Entomis) obliqua var. kuckersiana
(Bonnema), C2.

Ctenobolbina (Entomis) oblonga var. kuckersiana
(Bonnema), C2.

Ctenobolbina (Primitia) rossica (Bonnema), C2.

Cytherellina jonesii Bonnema, C2.

Cytherellina krausei Bonnema, C2.

Cytherellina ruedemanni Bonnema, C2.

Cytherellina ulrichi Bonnema, C2.

Entomis quadrispina Krause, C2.

Entomis variolaris Bonnema, C2.

Eurychilina (Primitia) decumana (Bonnema), C2.

Eurychilina (Primitia) dentifera (Bonnema), C2.

Eurychilina (Entomis) flabellifera (Krause), C2.

Eurychilina (Primitia) kapteyni (Bonnema), C2.

Eurychilina (Primitia) kuckersiana Bonnema, C2.

Leperditia brachynota Schmidt, F2.

Macronotella kuckersiana Bonnema, C2.

Primitia esthonica Bonnema, C2.

Primitia molli Bonnema, C2.

Primitia tolli Bonnema, C2.

Primitiella kuckersiana Bonnema, C2.

Tetradella calkeri Bonnema, C2.

Tetradella calkeri var. convera Bonnema, C2.

Tetradella (Strepula) kuckersiana Bonnema, C2.

Tetradella (Strepula) kuckersiana var. acuta Bon-
nema, C2.

Ulrichia ef. bidens Krause, C2.

Ulrichia kuckersiana Bonnema, C2.

Although not as abundant as in the Kuckers
shale, Ostracoda are present in all the Russian
formationsexcept Aand B1. A few of them have
been described, but not definitely placed in the

section.
TRILOBITA.

Acidaspis kuckersiana Schmidt, C2.

Acidaspis kuckersiana var. mickwitzi Schmidt, D2.

Agnostus glabratus var. ingrica Schmidt, B2a, B2b.

Agnostus glabratus var. insignis Schmidt, B2c.

Am~phion brevicapitatus Lamansky, B2b, B2c.

Amphion fischeri Eichwald, B3a, B3b, B3c, B2e.

Ampyt dubius Schmidt, Cla.

Ampyz knyrkot Schmidt, B2c.

Ampyz linnarssoni Schmidt, B2a.

Ampyz nasutus Dalman, B2c, B3a, B3b.

Ampyz rostratus Dalman, Clb, C2.

Ampyz volborthi Schmidt, B3a, B3b.

A patocephalus serratus Sars and Boeck, Blb, B2b,
B2a, B2c.

Arges wesenbergensis Schmidt, E, F1.

Asaphus acuminatus Sars and Boeck, B3a.

Asaphus broggerit Schmidt, B2b.

Asaphus cornutus Pander, Cla.

Asaphus cornutus var. holmi Schmidt, Cla.

Asaphus delphinus Lawrow, Cla.

Asaphus deverus Eichwald, C1b.

Asaphus deverus var. applanata Schmidt, Cla.

Asaphus eichwaldi Schmidt, B3b, Cla.

Asaphus eichwaldi var. expansoides Lamansky, B3c.

Asaphus eichwaldi var. lepiduroides Lamansky,
Bac.

Asaphus erpansus Dalman, B3a.

Asaphus kowalewskii Lamansky, B3c, Cla.

Asaphus lzvissimus Schmidt, Cla.

Asaphus lzvissimus vat. laticauda Schmidt, Cla.

Asaphus lamanskii Schmidt, B3a.

Asaphus latus Pander, Cla.

Asaphus latus var. plautini Schmidt, Cla.

Asaphus lepidurus Nieszkowski, B2c.

Asaphus major Schmidt, B3b, B3c.

Asaphus nieszkowskii mut. itferensis Schmidt, C3.

Asaphus nieszkowskii mut. jewensis Schmidt, D1.

Asaphus nieszkowskii mut. kegelensis Schmidt, D2.

Asaphus nieszkowskii cf. lepidus Tornquist, Clb, C2.

Asaphus ornatus Pompeckj, Cla, Clb.

Asaphus pachyophthalmus Schmidt, B3c.

Asaphus platyurus Angelin, Cla.

Asaphus platyurus var. laticauda Schmidt, Cla

Asaphus priscus Lamansky, B2a.

Asaphus raniceps Dalman, B3b.

Basilicus kegelensis Schmidt, D1.

Basilicus kuckersiana Schmidt, C2.

Basilicus lawrowi Schmidt, Cla, Clb.

Bronteus laticauda Wahlenberg, F1.

Calymmene senaria Conrad, F2.

Calymmene stacyi Schmidt, F1, F2.

Ceratolichas inerpectatus Schmidt, C2.

Chasmops brevispina Schmidt, D1.

Chasmops bucculenta Sjogren, D1, D2.

Chasmops eichwaldi Schmidt, F1, F2.

Chasmops marginata Schmidt, D1, D2.

Chasmops maxima Schmidt, D1, D2.

Chasmops mutica Schmidt, D1, D2.

Chasmops nasuta Schmidt, Cla.

Chasmops odini Hichwald, Clb, C2.

Chasmops odini var. itferensis Schmidt, C3.

Chasmops precurrens Schmidt, Cla, Clb.

Chasmops wenjukowi Schmidt, D1.

Chasmops wesenbergensis Schmidt, E,F1.

Chasmops wrangeli Schmidt, C3.

Cheirurus ersul Beyrich, Cla.

Cheirurus cf. glaber Angelin, F1.

Cheirurus gladiator Eichwald, Clb.

Cheirurus ingricus Schmidt, B3b.

Cheirurus insignis Schmidt, B3a.

Cheirurus macropthalmus Kutorga, Clb.

Cheirurus ornatus Dalman, B2c, B3b, B3c.

Cheirurus spinulosus Nieszkowski, C1b, C2, C3.

Conolichas equilobus Steinhardt, D1, D2.

Conolichas schmidti Dames, D2.

Conolichas triconicus Dames, C3.

Crotalurus barrandet Volborth, B3a, B3b, B3c, Cla.

Cybele affinis Schmidt, Cla.

Cybele bellatula Dalman, B3a, B3b.

Cybele hellatula var. wohrmanni Schmidt, B2c.

Cybele brevicauda Angelin, KE, F1.

Cybele coronata Schmidt, C2.

Cybele grewingkii Schmidt, D1, D2.

Cybele kutorgze Schmidt, C3, D1, D2.

Cybele panderi Schmidt, B3a, B3b, B3c, Cla.

Cybele revaliensis Schmidt, C1b.

Cybele rex Nieszkowski, C2, C3.

Cybele wortht Hichwald, Cla, Clb.

Cyphaspis planifrons Kichwald, C2.

Cyrtometopus affinis Angelin, B3a, B3b, B3c.

Cyrtometopus aries Schmidt, Cla, Clb.

Cyrtometopus cf. aries Schmidt, B2a, B2c.

Cyrtometopus clavifrons Dalman, B2a, B2b, B2e.

Cyrtometopus gibbus Angelin, B2b.

Cyrtometopus plautini Schmidt, C2.

Cyrtometopus primigenius var. lamanskiit Schmidt,
Bib.

24 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Cyriometopus pseudohemicranium Nieszkowski, D1.

Cyrtometopus pseudohemicranium var. dolichoce-
phala Schmidt, C2, C3.

Cyriometopus tumidus Angelin, B2c.

Diaphanometopus volbortht Schmidt, B2c, B3a.

Encrinurus multisegmentatus Portlock, E, F1, F2.

Encrinurus seebachi Schmidt, E, F1.

Har pes spasskii Hichwald, B2c, B3a, Cla.

Har pes wegelini Angelin, F1.

Harpides plautini Schmidt, B2a, B2b, B2c.

Homolichas angustus (Beyrich), F1, F2.

Homolichas deflexus (Sjogren), D2.

Homolichas depressus (Angelin), C2.

Homolichas eichwaldi (Nieszkowski), E,? F1.

Homolichas pahleni Schmidt, D1.

Hoplolichas conicotuberculatus Nieszkowski, C1b, C2.

Hoplolichas furcifer Schmidt, Cla.

Hoplolichas plautini Schmidt, Cla, Clb.

Hoplolichas tricuspidatus (Beyrich), Cla, C1b.

Hoplolichas tricuspidatus var. longispina Schmidt,
C2.

Mlenus angustifrons Holm, F1, F2.

Ilznus ariensis Holm, Cla.

Tllenus atavus Eichwald, Cla.

Illnzus cecus Holm, F1.

Tllenus centrotus Dalman, B2a, B2b, B2c, B3b.

Tllznus centrotus var., B3a.

Illenus chiron Holm, Clb.

Tllenus chudleighensis Holm, Cla.

Mlxnus crassicauda (Wahlenberg), Cla, Clb.

Tllenus dalmani Volborth, Cla.

Tllznus esmarckii Schlotheim, B3a, B3b, B3c.

Tllenus intermedius Holm, Cib.

Tllenus jewensis Holm, D1, D2.

Tllznus ladogensis Holm, B3a.

Tllznus laticlavius Eichwald, B38b, B3ec.

Tllznus linnarssoni Holm, C2, C3, D2, E, F1.

Tlzxnus masckei Holm, F1.

Milxnus oblongatus Angelin, Cla, Clb, C2, C3.

Ilznus.oculosus Holm, Cla.

Ilznus plautini Holm, Cla, Clb.

Iilznus revaliensis Holm, B3c.

Tllenus romeri Volborth, Clb, F1, F2.

Tllenus schmidti Nieszkowski, Cla, Clb.

Mznus sinuatus Holm, Cla.

Mlznus sphzricus Holm, C2, C3.

Meznus sulcifrons Holm, Cla.

Tllxnus tauricornis Kutorga, Cla, Clb.

Mlenus triquetrus (Volborth), C1b.

Tsotelus platyrhachis Steinhardt, F1.

Isotelus remigium Hichwald, E.

Isotelus robustus Roemer, F1, F2.

Leiolichas illenoides Nieszkowski, D1, D2.

Megalaspides schmidti Lamansky, B1b.

Megalaspis acuticauda Angelin, B2c, B3a, B3b.

Megalaspis centron Leuchtenberg, B3a.

Megalaspis gibba Schmidt, B3a, B3b.

Megalaspis gibbosa Schmidt, B2c.

Megalaspis heros Dalman, B3b, B3e.

Megalaspis hyorrhina Schmidt, B2b.

Megalaspis knyrkoi Schmidt, B2c.

Megalaspis kolenkot Schmidt, B2b.

Megalaspis lawrowi Schmidt, B3a, B3b, Cla.

Megalaspis limbata Sars and Boeck, B2a.

Megalaspis longicauda Leuchtenberg, B3c.

Megalaspis mickwitzi Schmidt, B2c.

Megalaspis planilimbata Angelin, Blb, B2a.

Megalaspis planilimbata var. leuchtenbergi Laman-
sky, Bib.

Megalaspis pogrebowi Lamansky, B1b.

Megalaspis polyphemus Brogger, B2a.

Menocephalus minutus (Nieszkowski), C2.

Mesonacis (Olenellus) mickwitzi (Schmidt), Al.

Metopias celorhin Angelin, B2c, B3a, B3b, B3e, Cla.

Metopias hubneri Eichwald, Cib.

Metopias kuckersianus Schmidt, Cib, C2.

Metopias pachyrrhina Dalman, B3a, B3b, B3c.

Metopias pachyrrhina var. longerostrata Schmidt,
B3a, B3b.

Metopias platyrhina Schmidt, B3a.

Metopias verrucosa Kichwald, B3b, B3c, B2e.

Nieszkowskia cephaloceras Nieszkowski, C1b, C2.

Nieszkowskia tumidus Angelin, Cla, Cib.

WNiesczkowskia variolaris (Linneeus), Clb, C2.

Nileus armadillo Dalman, B3a.

WNileus armadillo var. depressa Sars and Boeck, B2b,
B2e.

Niobe emarginula Brogger, B3a, B3b.

Niobe frontalis Dalman, B3a, B3b.

Niobe lzviceps Dalman, B1b, B2a.

Niobe lindstromi Schmidt, B2b.

Niobe volborthit Schmidt, B3a.

Ogygia dilatata var. panderi Schmidt, C2.

Ogygia dilatata var. plautini Schmidt, Cla.

Onchometopus schmidti Lamansky, B2e.

Onchometopus stacyi Schmidt, B3c.

Onchometopus volborthi Schmidt, B2b, B2e, C3.

Pharostoma denticulata Eichwald, Cla.

Pharostoma nieszkowskii Schmidt, C2.

Pharostoma pediloba Roemer, E, F1.

Platylichas cicatricosus Loven, F2.

Platylichas docens Schmidt, F1.

Platylichas hamatus Schmidt, F1.

Platylichas laxatus McCoy, F1.

Platylichas margaritifera Nieszkowski, F2.

Platylichas st. mathiz Schmidt, D1.

Platymetopus dalecarlicus Angelin, F1.

Platymetopus holmi Schmidt E.

Platymetopus lzvis Eichwald, F1.

Platymetopus lineatus Angelin, F1.

Proetus kertelensis Schmidt, F1.

Proetus ramisulcata Nieszkowski, F1, F2.

Proetus wesenbergensis Schmidt, E.

Proetus wohrmanni Schmidt, B2c, B3a.

Pseudasaphus globifrons Hichwald, B3c.

Pseudasaphus tecticaudata Steinhardt, Cla, Clb, C2.

Pseudasaphus tecticaudata var. precurrens Schmidt, —

B3e, Cla.
Pseudosphzrexochus conformis Angelin, F1, F2.
Pseudosphzrexochus hemicranium Kutorga, Clb.
Pseudospherexochus pahnschi Schmidt, D2.
Pseudosphxrerochus roemeri Schmidt, F1, F2.
Pterygometopus exilis Hichwald, Clb, C2.
Pierygometopus kegelensis Schmidt, D2.
Piterygometopus kuckersiana Schmidt, C2.
Pterygometopus levigata Schmidt, C3, D1, D2.
Pterygometopus nieszkowskiz Schmidt, E.
Pterygometopus panderi Schmidt, Cla, Clb.
Pierygometopus sclerops Dalman, B2b, B2c.
Pterygometopus trigonocephala Schmidt, B2c, B3a,

B3b.
Ptychometopus volbortht Schmidt, B2a, B2b, B2c.
Piychopyge angustifrons Dalman, B2a, B2b, B2e,

B3a, B3b.

Ww

—— ee See

ee

Pa a, A, A_POST ee a,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 25

Piychopyge angustifrons var. gladiifera Schmidt, B3a | Remopleurides elongatus var. elongata Schmidt, C2.

Piychopygecincta Brogger, B2c. Remopleurides emarginatus Tornquist, F1.
Ptychopyge globifrons Eichwald, B3c. _ | Remopleurides nanus Leuchtenberg, B2a, B3a, B3b
Ptychopyge inostranzewi Lamansky, B1b. B3e, Cla.
Piychopyge knyrkot Schmidt, B2c. Spheretochus angustifrons Angelin, C3, F1.
Piychopyge limbata Angelin, B2c, B3a. Sphezrexochus conformis Angelin, F1, F2.
Piychopyge pahleni Schmidt, B2a, B2b, B2c. Sphezrezochus roemeri Schmidt, F1, F2.
Piychopyge plautini Schmidt, B2b, B2c. Spherocoryphe cranium Kutorga, C1b, C2.
Ptychopyge truncata Nieszkowski, B2c. Sphzrocoryphe hubneri Schmidt, C3.
Piychopyge truncata var. bréggeri Schmidt, B2c, | Sphxrocoryphe granulata Angelin, F1, F2.

B3a. Trinucleus seticornis Hisinger, F1.

ORDOVICIAN FORMATIONS OF UPPER MISSISSIPPI VALLEY.

The general time scale of early Paleozoic deposits in North America
is indicated in the table on page 38, but of all these formations only
those of the Ordovician and early Silurian need be discussed in the
present work, since the Cambrian, Ozarkian, and Canadian contain,
with two possible exceptions, no Bryozoa.

In the preceding pages I have pointed out that the bryozoan faunas
of Baltic Russia from formations hitherto assigned to the Ordovician
(Lower Silurian), are closely allied to those contained in strata of
Middle Ordovician and early Silurian age in northern North America,
and especially in the upper part of the Mississippi Valley. The strati-
graphy and paleontology of these two time divisions have received
much study in Iowa, and more especially in Minnesota, so that the
section in these two States can now be used for comparison. The
composite section and a discussion of the individual beds follows:

Composite geologic section of Ordovician, northeastern Iowa and southeastern Minnesota.

Feet.
Pel aotuniam (AiCMmMoOMd STOUP)). o2 2 6c. ce ade ee chee Nee ice ees _—
Ordovician:
Trenton group—
Stewartville dolomite—
(b) Porous, soft, yellowish dclomite and mottled magnesian lime-
stone (Maclurea bed) containing the Maclurina manitobensis
Pena eee bao ee eg eee cate as Se Ma Mae MS a ay one ee bey Soria wy Suatats 0-100
(a) Unfossiliferous, sandy mudstone.........-....-...=-----..---- 0-20

Prosser limestone—
(c) Cherty, nonmagnesian, light blue, fine-grained limestone.... 10-20
(6) Thin bedded, occasionally shaly, fine-grained, bluish lime-
stone containing the Fusispira bed fauna. Locally the
basal strata of this division contain the fauna of the Nema-
[HCO] LOLs |e re Vat es See ule tee eis ae Cea Lee tear et ees ee 20-35
(a) Thin bedded, shaly limestone containing large examples of
Receptaculites owent at the top and the Clitambonites bed
PAUTIAIAT TAO WASel=. sae prraccis Nets Sea a aia eke AINE oe ee? 20-45
Black River group—
Decorah shale—

26 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Ordovician—Continued.
Black River group—Continued.

Decorah shale—Continued. Feet.

(e) Gray, greenish or blue shale with nodular gray limestone in

the upper part and knotty, calcareous masses in the re-

mainder. (Fucoid bed.) Dinorthis pectinella and Camaro-

cladia rugosa abundant, but other fossils are rare and are of
species found in the underlying bed.................----- 0-10

(d) Blue shale weathering greenish gray, with fossiliferous, even or

knotty plates of limestone. Fossils abundant. (Phyllopo-

PUMA DEM) cz ake las Si eters eles Me aes OU ce ee en 10-15
(c) Green to blue shales with numerous bryozoans and mollusca.
(Ctenodonta bed. )is cst so Ree ee eee 0-10

(6) Greenish blue shale with a few thin plates of limestone.
Fossils numerous, chiefly bryozoans. (Rhinidictya bed.).. 0-34
(a) Soft green shales and irregular layers of limestone with numer-
ous fossils, particularly bryozoans. (Stictoporella bed.).... 3-10
Platteville limestone (Lowville age)—
(b) Blue to gray fine-grained dolomite weathering brownish to
yellow. Fossils occurring as casts, numerous in certain

layers) (Vanuxemia bed))a¢ 32 se eas eee 0-12
(a) Thin bedded, fine-grained, locally somewhat argillaceous
limestone, often cobbly or shaly toward the base.......-..-- 15-28

Stones River group—
“‘Lower Buff” dolomite—
Bluish gray dolomite, weathering grayish buff, more or less cellu-
lose, usually thick bedded in the middle part, thin and impure
above, and sometimes conglomeratic and sandy at the base.
Mosstls fews 22s sccc05 <2 oo. pete See eens See 6-13
Glenwood shales— ;
Soft green shale or clay, the lower part of a rusty color, and com-
monly with grains of quartz sand derived from the underlying
be Peter see i.e L2 S ne Te a shee Teen ee ee 1-6

STONES RIVER GROUP.

The best development of this group is in its type-locality, central
Tennessee, where its several formations are quite fossiliferous. Hach
of the Stones River faunas seems to be of southern origin and to have
little in common with those of the Black River. With the exception
of one or two species of the long-lived Corynotrypa, not a single
bryozoan of the many known Stones River forms is strictly identical
with any in the Black River group or in the Baltic Ordovician. The
few fossils found in the St. Peter sandstone, Glenwood shale, and
‘Lower Buff” dolomite, comprising the Stones River of the Minne-
sota-lowa basin of. deposition, likewise have little relationship to the
faunas of later times and need not be mentioned further. A con-
siderable number of species has been recorded from the ‘‘Lower
Buff”? dolomite, but, almost without exception, these belong to the
lower members of the Platteville limestone described later.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. ilk
BLACK RIVER GROUP.

The extensive development of this group in the Minnesota-lowa
area was pointed out about 15 years ago by Ulrich, and is indicated
by the same writer in his recent work upon the revision of the Paleo-
zoic systems of North America. During Black River time, oscilla-
tions of the continental sea were frequent and are manifested in
numerous unconformities. At no single locality are all of the divi-
sions noted in the composite section developed, but most of these are
present at and in the vicinity of St. Paul. To the south in Minnesota
and in northern Iowa the overlaps are more pronounced and the
hiatuses more frequent. Farther south, in eastern Missouri, the
Black River deposits of Minnesota and Iowa are overlapped by the
uppermost division assigned to the group, the Kimmswick formation,
a crystalline limestone containing specimens of Hchinospherites which
can not be distinguished from the common Baltic species. The
faunas of the several Black River formations are quite large and
characteristic. They have been described by Ulrich, Clarke, Schu-
chert, Winchell, and Scofield, in the third volume of the ‘‘Geological
and Natural History Survey of Minnesota,’ where the Black River
group is referred to as the ‘‘Trenton shales,” or as the “‘Black River
shales.”’ Complete lists of these various faunas are given in the
introduction to part 2 of the volume. Here the Black River shales
are divided into four beds, named in ascending order, according to
the characteristic fossils, the Rhinidictya bed, Ctenodonta bed,
Phylloporina bed, and Fucoid bed. In this introduction, the Sticto-
porella bed, forming the lowest division of the ‘“Trenton shales’”’ of
previous reports, was assigned to the Stones River group, but more
extended study on the part of Ulrich has convinced him that this
bed should form the introductory strata of the Black River shales,
or, as they are now known, the Decorah shales. Trenton shales,
Black River shales, and Decorah shales, as the terms are employed
for this area, are, therefore, synonymous. The underlying Upper
Buff and Lower Blue limestones of the region contain the fauna
characteristic of the Lowville formation of New York, and, following
the more recent stratigraphic work, they are regarded as the lowest
division of the Black River group. To this division the name
Platteville limestone has been applied by Bain.

THE BRYOZOAN FAUNAS OF AMERICAN BLACK RIVER AND
EARLIEST TRENTON DEPOSITS.

The earliest Black River deposits of the upper Mississippi Valley
are of blue to gray fine-grained dolomitic and argillaceous limestone
apparently little suited to bryozoan life, although fossils of other
classes are often quite numerous. The few bryozoans that do occur

92602°—Bull, 77—11—_—4

28 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

are almost always found on the surface of thin-bedded limestone
layers containing more calcareous material than usual. As indicated
in the following table, but a single species of this fauna has been
noted in Russian strata.

BRYOZOA OF THE PLATTEVILLE LIMESTONE IN MINNESOTA: 1!

Rhinidictya trentonensis Ulrich.
Rhinidictya nicholsoni Ulrich.
Rhinidictya pediculata Ulrich.

Escharopora angularis Ulrich.
*Leptotrypa hexagonalis Ulrich.

The soft green shales and thin-bedded limestones comprised in the
first division of the Decorah shale, the Stictoporella bed, frequently
contain so many bryozoans that other fossils, in comparison, seem
to be wanting. Several species of Stictoporella, Pachydictya frondosa,
and Anolotichia impolita, are characteristic of the bed, but a majority
of the species pass into the succeeding beds of the Decorah shale.
Of the entire fauna, 38 species, 14 are present in the Baltic Middle
Ordovician, where most of them occur in the formations ranging
from B3 to D3.

cy

BRYOZOA OF THE STICTOPORELLA BED.

*Corynotrypa delicatula (James).
Berenicea minnesotensis Ulrich.
Favositella laxata Ulrich.
*Anolotichia impolita Ulrich.
Ceramoporella distincta Ulrich.
Ceramoporella inclusa Ulrich.
*Rhinidictya mutabilis Ulrich.
Rhinidictya exiqgua Ulrich.
Rhinidictya fidelis Ulrich.
Rhinidictya trentonensis Ulrich.
Pachydictya foliata Ulrich.
Escharopora angularis Ulrich.
Escharopora ? limitaris Ulrich.
*Hscharopora subrecta Ulrich.
*Arthropora simplex Ulrich.
Stictoporella angularis Ulrich.
*Stictoporella cribrosa Ulrich.
Stictoporella angularis intermedia Ulrich.
Stictoporella frondifera Ulrich.

* Arthrostylus obliquus Ulrich.
*Helopora divaricata Ulrich.
*Chasmatopora reticulata (Hall).
Monticulipora grandis Ulrich.
Homotrypa minnesotensis Ulrich.
Homotrypa exilis Ulrich.

Homotrypa separaia Ulrich.
Aspidopora parasitica Ulrich.
*Dekayella prenuntia simplex Ulrich.

*Dekayella prenuntia nxvigera Ulrich.

Hallopora angularis (Ulrich).
Hallopora incontroversa (Ulrich).
*Batostoma fertile Ulrich.
*Batostoma fertile circulare Ulrich.
Batosioma ? decipiens Ulrich.

* Hemiphragma irrasum Ulrich.
Stomatotrypa ovata Ulrich.
Nicholsonella ponderosa Ulrich ?.
Leptotrypa informis Ulrich.

The lithology of the next bed, named the Rhinidictya bed on
account of the large number of Rhinidictya mutabilis contained in
it, is very similar to the underlying Stictoporella bed. The simi-
- larity is borne out by the faunas, which differ only because of tae
new species introduced. Of the bryozoans, 58 species have been
described, and of these 23 are known in the Baltic strata
underlying F1.

1 Tn this and the following lists, all species marked (*) are common to Russia and America.

Se ee

t= 3

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES., 29

BRYOZOA OF THE RHINIDICTYA BED.

*Stomatopora arachnoidea (Hall). *Homotrypella hospitalis crassa (Ulrich).
*Corynotrypa barberi Bassler. - Homotrypa intercalaris Ulrich.
*Corynotrypa delicatula (James). *Homotrypa subramosa Ulrich.

Berenicea minnesotensis Ulrich. Aspidopora parasitica Ulrich.

Spatiopora labeculosa Ulrich. Mesotrypa infida Ulrich.

Favositella laxata Ulrich. Mesotrypa ? spinosa Ulrich.
Ceramoporella inclusa Ulrich. Bythopora herricki Ulrich.

*Rhinidictya mutabilis Ulrich. a *Bythopora subgracilis (Ulrich).
Rhinidictya mutabilis major Ulrich. *Dekayella prenuntia Ulrich.

Rhinidictya mutabilis senilis Ulrich. *Dekayella prenuntia simplex Ulrich.
Rhinidictya exigua Ulrich. Dekayella prenuntia echinata Ulrieh.
Phyllodictya frondosa Ulrich. Dekayella prenuntia multipora Ulrich.
*Phyllodictya varia Ulrich. * Hallopora undulata (Ulrich).
Pachydictya fimbriata Ulrich. * Hallopora multitabulata (Ulrich).
*Escharopora subdrecta Ulrich. Hallopora ampla (Ulrich).

Escharopora confluens Ulrich. *Batostoma magnoporum Ulrich.
Escharopora ? limitaris Ulrich. Batostoma varium Ulrich.

*Arthropora simplex Ulrich. *Batostoma winchelli Ulrich.
*Stictoporella cribrosa Ulrich. *Batostoma winchelli spinulosum Ulrich.
Helopora alternata Ulrich. Batostoma minnesotense Ulrich.
Arthroclema striatum Ulrich. Batostoma ? decipiens Ulrich.

Arthroclema cornutum Ulrich. * Hemiphragma wrrasum Ulrich.
*Chasmatopora reticulata (Hall). Stromatotrypa ovata Ulrich.
Monticulipora incompta Ulrich. *Trematopora ? primigenia Ulrich.
Atactoporella typicalis precipta Ulrich.. Trematopora ? primigenia ornata Ulrich.
Atactoporella insueta Ulrich. Tremato pora ? prémigeniaspinulosa Ulrich.
*Homotrypella instabilis Ulrich. Nicholsonella laminata Ulrich.
Homotrypella multiporata Ulrich. Nicholsonella ponderosa Ulrich.
Homotrypella ovata Ulrich. *Stigmatella claviformis Ulrich.

The Ctenodonta bed division of the Decorah shales is scarcely
distinguishable from the Rhinidictya bed at most localities. In
Goodhue County, Minnestoa, it contains few bryozoans, but an
abundance of Mollusca of which species of Ctenodonta are most com-
mon. The few bryozoans registered from this bed show an unusual

percentage common to Russia and America.

BRYOZOA FROM THE CTENODONTA BED.

*Corynotrypa delicatula (James). *Stictoporella cribrosa Ulrich.
*Spatiopora lineata incepta Ulrich. Dekayella prenuntia echinata Ulrich.
*Rhinidictya mutabilis Ulrich. *Hallopora undulata (Ulrich).
Rhinidictya mutabilis major Ulrich. Batostoma varium Ulrich.
Pachydictya fimbriata Ulrich. *Stigmatella claviformis Ulrich.

Following the Ctenodonta bed are shales much resembling those of
the Rhinidictya bed, and like them, crowded with Bryozoa. Here,
however, the bifoliate forms are less abundant and monticuliporoids
predominate. Phylloporina, or, as it should now be called, Chasma-
topora, is present, often in great numbers, giving the name to the divi-
sion. The Fucoid bed which succeeds the Phylloporina contains a

30 BULLETIN 177, UNITED STATES NATIONAL MUSEUM.

limited fauna, mainly because it seems ill-suited for bryozoan life.
The few species occurring in it are listed below with those of the
Phylloporina bed. The entire bryozoan fauna amounts to 50 species,
with 16 occurring also in the Baltic area.

BRYOZOA OF THE PHYLLOPORINA AND FUCOID BEDS.

* Vinella repens Ulrich. Atactoporella ramosa Ulrich.
*Stomatopora arachnoidea (Hall). *Homotrypella cribrosa Bassler.

* Corynotrypa delicatula (James). * Homotrypella hos pitalis crassa (Ulrich).
*Corynotrypa inflata (Hall). Homotrypa minnesotensis Ulrich.
Proboscina tumulosa Ulrich. *Homotrypa subramosa Ulrich.
*Ceramoporella granulosa minor Bassler. Homotrypa tuberculata Ulrich.
Crepipora subxquata Ulrich. Prasopora simulatriz Ulrich.
Favositella laxata Ulrich. Prasopora contigua Ulrich.
Ceramoporella inclusa Ulrich. Prasopora conoidea Ulrich.
Celoclema trentonense Ulrich. Prasopora lenticularis Ulrich.
Ceramophylla frondosa Ulrich. Bythopora alcicornis Ulrich.
*Rhinidictya mutabilis Ulrich. *Eridotrypa xdilis (Hichwald).
Rhinidictya mutabilts major Ulrich. *Hridotrypa xdilis minor (Ulrich).
Rhinidictya paupera Ulrich. Dekayella prenuntia echinata Ulrich.
Rhinidictya exigua Ulrich. Dekayella trentonensis (Ulrich).
Eurydictya multipora (? Hall). *Hallopora multitabulata (Ulrich).
Pachydictya occidentalis Ulrich. Hallopora ampla (Ulrich).
Trigonodictya conciliatrix Ulrich. * Hallopora dumalis (Ulrich).
Arthropora bifurcata Ulrich. Hallopora pulchella (Ulrich).
Stictoporella rigida Ulrich. Hallopora pulchella persimalis (Ulrich).
Stictoporella dumosa Ulrich. Calloporina crenulata (Ulrich).

* Arthrostylus conjunctus Ulrich. Batostoma montuosum Ulrich.
Arthroclema pulchellum Billings. * Hemiphragma irrasum Ulrich.
Chasmatopora hallt (Ulrich). Stellipora antheloidea Hall.
Chasmatopora corticosa (Ulrich). *Stigmatella claviformis (Ulrich).

The Fucoid bed closes the Black River in Minnesota, but in north-
ern Iowa a shaly gray limestone filled with a variety of Prasopora in-
sularis forms the last apparent member of the group. Numerous
bryozoans occur iu this bed, but lists of the species have never heen
published. However, the fauna is essentially the same as the under-
lying Black River shales with about 40 per cent of the species present
in the Russian deposits.

As indicated in the correlation table on page 38, the Trenton strata
of the upper Mississippi Valley comprise only the lower portion of this
group. In Minnesota the group may be divided into four faunal
zones. The lowest consists of yellowish to light green shales with in-
terbedded thin, impure limestones. Fossils of all classes are rather
numerous, although the bryozoans as usual make up the largest part
of the fauna. A species of Clitambonites is one of the characteristic
fossils and has given the name to the bed. Thirty-six species of
bryozoans have been recorded from the Clitambonites bed, and of
these, 16 occur also in the Baltic Middle Ordovician. The similarity

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. ol

of the Clitambonites bed to the Wesenberg limestone has been
remarked upon in a preceding paragraph.

BRYOZOA OF THE CLITAMBONITES BED.

*Stomatopora arachnoidea (Hall).
*Corynotrypa delicatula (James).

* Corynotrypa inflata (Hall).
Ceramoporella interporosa Ulrich.
*Rhinidictya mutabilis Ulrich.

* Pachydictya elegans Ulrich.
Pachydictya acuta Hall.
*Graptodictya proava (Eichwald).
Esscharopora recta Hall.
Phxnopora incipiens Ulrich.
Arthropora bifurcata Ulrich.
Arthropora reversa Ulrich.
Helopora mucronata Ulrich.
Arthroclema pulchellum Billings.
Monticulipora arborea Ulrich.
Monticulipora cannonensis Ulrich.
*Homotrypella hospitalis crassa Ulrich.
Hemotrypella ovata Ulrich.

Homotrypella mundula Ulrich.
*Homotrypa subramosa insignis Ulrich.
*Homotrypa similis Foord.
Homotrypa callosa Ulrich.
Prasopora insularis Ulrich.
Aspidopora elegantula Ulrich.
*Hridotrypa edilis (Kichwald).
*Hridotrypa xdilis minor Ulrich.
Dekayella trentonensis Ulrich.

* Hallopora multitabulata (Ulrich)
FHallopora ampla (Ulrich).

* Hallopora goodhuensis (Ulrich).
Calloporina crenulata (Ulrich).

* Hallopora dumalis (Ulrich).
Batostoma humile Ulrich.
*Hemiphragma wrasum Ulrich.

* Hemiphragma tenuimurale Ulrich.
Leptotrypa acervulosa Ulrich.

- bryozoan species herewith given.

The two next faunal zones of the Minnesota-Trenton, the Nemato-
pora bed and the Fusispira bed, have been combined in the list. of
It will be noted that of the 40
species in these beds only 14 are common to the American and Baltic
areas. No bryozoans have been found in the Maclurea bed which
terminates the Minnesota-Trenton. The next overlying rocks are
of earliest Silurian (Richmond) age, and contain the fauna of the
upper Lyckholm and Borkholm limestones, at least so far as the
bryozoans and corals are concerned.

BRYOZOA OF THE FUSISPIRA AND NEMATOPORA BEDS.

*Stomatopora arachnoidea (Hall).
*Corynotrypa delicatula (James).
* Corynotrypa inflata (Hall).
Berenicea minnesotensis Ulrich.
Diastoporina flabellata Ulrich.
Favositella laxata Ulrich.
Celoclema trentonensis Ulrich.

* Mitoclema ? mundulum Ulrich.
Rhinidictya exigua Ulrich.
Rhinidictya minima Ulrich.
Pachydictya pumila Ulrich.
Pachydictya acuta Hall.
Pachydictya magnipora Ulrich.
Nematopora conferta Ulrich.

* Nematopora consueta Bassler.
Nematopora granosa Ulrich.

* Nematopora ovalis Ulrich.

Helopora quadrata Ulrich.
Helopora mucronata Ulrich.

* Arthroclema armatum Ulrich.
*Chasmatopora reticulata (Hall).
Monticulipora grandis Ulrich.
Prasopora simulatrix Ulrich.
Prasopora selwyni Nicholson.
Prasopora oculata Foord.
Prasopora affinis Foord.
Homotrypa callosa Ulrich.

* Homotrypa similis Foord.
Mesotrypa quebecensis Ari.
Mesotrypa discoidea Ulrich.
Mesotrypa ? rotundata Ulrich.
*Eridotrypa xdilis (Eichwald).
*Eridotrypa exigua Ulrich.

* Hemiphragma tenuimurale Ulrich.

32 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Hemiphragma ottawense (Foord). *Dianulites petropolitana Dybowski (Mon-
Diplotrypa limitaris (Ulrich). otrypa cumulata Ulrich).
Diplotrypa neglecta Ulrich. *Constellaria varia Ulrich.

Monotrypa intabulata Ulrich.

Tabulating the preceding lists of bryozoans with the total number of
American species and the number of species common to American
and Baltic areas, it will be noted, as may be determined from the

following table, that on an average about 35 per cent of the species .

are alike in the two regions.

Summary of American and Baltic Ordovician bryozoa.

Number of
Total : species
2 number of | common to
Formation. American | American
species. | and Baltic
areas.
Trenton group:
Fusispira and Nematopora DCSE =: Saket as pens ee ees eps be eet eg er ae 40 14
Chigamibonibes pede re eee eee ete eee ee ae eer ere ee 36 16
Black River group:
Decorah shale—
Tah AMO) NOMA INA « sc ese werces sobeesoscusesessccurnsascosesssassese = 50 16
(Oirerereys lara) Volos se casa ac eacesa a sas apace seosasee ocdsbcHeScoseestos 10 6
igor ChO AE) Clos tcosccudsecasos sees + sesso Tessosedancesseteauecsccss 58 23
SLE BO PO HEN ako Cl eee ae ee ee ee eee 38 14
Pleyel han HONS ==. Sec seadesssacsunocseoseteelseccesascescesesscscage: 5 i

This percentage of common species is almost duplicated in the
summary of Baltic and American forms given on page 50, where the
species are tabulated with reference to the Russian formations.
Excluding the Lyckholm and Borkholm bryozoans believed to be of

early Silurian age, there are 134 Ordovician species described in this .

work, with 52 common to the two areas, thus giving practically the
same percentage. This similarity of percentages leads me to believe
that, even with more work upon these bryozoan faunas, the number
of new species will be counterbalanced by the chenern of American
forms in such a ratio as to maintain about this same figure.

ORDOVICIAN AND EARLY SILURIAN STRATA OF ARCTIC AMERICA.

The northward extension of the early Paleozoic strata in America
is of importance to substantiate the assumption that the Baltic
faunas usually entered this country from the north. As far back as
1854 siliceous limestones holding Black River or Chazy fossils were
reported by Alexander Murray as occurring on islands in Lake Nipis-
sing, northern Ontario. Later N. H. Winchell* described this lime-
stone as resting unconformably upon the gneiss and trap rocks of the
islands, and published the following list of fossils determined by
K. O. Ulrich:

1 Amer. Geologist, vol. 18, 1896, pp. 178-179.

Soe ee ee Se

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 33

BLACK RIVER FOSSILS FROM ISLANDS OF LAKE NIPISSING, ONTARIO.

Ormoceras tenuifilum Hall. *Batostoma winchelli Ulrich
*Hscharopora subrecta Ulrich. *Callopora multitabulata Ulrich.
Helopora mucronata Ulrich. Rhynchotrema inequivalvis Castelnau.
Escharopora ? limitaris Ulrich. Leperditia fabulites Conrad.
Rhinidictya mutabilis var. major Ulrich. | Aparchites neglectus Ulrich.

* Phyllodictya varia Ulrich.

This list is evidence of the equivalence of the Nipissing strata with
the Black River strata of Minnesota and Iowa. The species marked
with an asterisk occur in the Baltic deposits, where also nearly every

one of the other bryozoan forms is represented by a variety or closely
related species.

Middle Ordovician faunas are known from a number of localities
in the far North. These areas have been discussed and the fauna of
the most important fossiliferous locality, Silliman’s Fossil Mount, at
the head of Frobisher Bay, Baffin Land, has been described by
Schuchert in an article entitled ‘“On the Lower Silurian (Trenton)
Fauna of Baffin Land.” + These various localities have been regis-
tered upon the accompanying paleogeographic map (fig. 3), and Schu-
chert’s conclusions as to the extent of the deposits and his summary
of results are copied below:

From the foregoing description of localities it appears that Middle Lower Silurian
horizons are very extensive in eastern Arctic America. Such are known in places
on either side of Hudson Strait, Frobisher Bay, the interior of Baffin Land, and to the
north of this land at various localities between latitudes 79° and 80° north. As far
as known, these strata unconformably overlie very ancient crystalline rocks, and are
in turn overlain by Upper Silurian beds of Niagara or Wenlock age. Lower Cambrian
rocks are found in southern Labrador, but in the region of Baffin Land such are not
known to be present. Here, then, there seems to be a complete break from the Lau-
rentian to the Trenton, followed by another break paleontologically, in the absence
of the Cincinnatian beds, and probably the lower horizons of the Upper Silurian.
The Lower Silurian fossils of this area indicate nothing older than the typical Tren-
ton of New York and the Galena of Wisconsin and Minnesota, and nothing younger
than the Utica stage of the United States. The thickness of these beds is not less than
900 feet, and probably exceeds this.

This summary is based on information known to the author, and, while the evidence
is meager, the essential geological age and the sequence of the rocks of Baffin Land
seem to be established [pp. 148-149].

* * * * * * *

The only Lower Silurian horizons known in northeastern Arctic America are of
Trenton and Uticaage. The latter zone appears only on the north shore of Frobisher
Bay, but the Trenton is found in various places from the north shore of Hudson Strait
to latitude 81° north. The Lower Silurian is thickest on Akpatok Island, where it is
from 400 to 500 feet in depth. Dr. Bell, however, estimates the entire thickness of
these strata in this region to be not less than 900 feet.

1 Proc. U. S. Nat. Mus., vol. 22, 1900, pp. 143-177.

34 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In Baffin Land, and apparently elsewhere in Arctic America, the Lower Silurian
strata rests unconformably on old crystalline rocks. To the north of Baffin Land, the
former are overlain by beds of Niagara or Wenlock age.

The Trenton faunas, occurring in various places around the insular Archaean nucleus
of North America, have much in common, and this indicates that the conditions at
that time were very similar, while the sea was in communication throughout. As
yet, however, the distribution of the strata, together with their faunas, are well known
only to the south and southeast of the Archaean nucleus, yet that of the west (Mani-
toba) and of the northeast (Baffin Land) show direct communication.

The Baffin Land fauna had an early introduction of Upper Silurian genera in the
corals Halysites, Lyellia, and Plasmopora. In Manitoba similar conditions occur in
the presence of Halysites, Favosites, and Diphyphyllum. Other Upper Silurian types
do not appear to be present.

The Trenton fauna of Silliman’s Fossil Mount, at the head of Frobisher Bay, has 72
species, of which 28 are restricted toit. This faunashows an intimate relationship with
that of the Galena of Minnesota, Iowa, and Wisconsin. Fifty-seven per cent of the
species of Baffin Land also occur in the Galena of the regions just mentioned.

The Trenton fauna of Baffin Land shows that the corals, brachiopods, gastropods,
and trilobites have wide distribution, and are therefore less sensitive to differing hab-
itats apt to occur in widely separated regions. On the other hand, the cephalopods,
and particularly the pelecypods, indicate a shorter geographical range. The almost
complete absence of Bryozoa in the Baffin Land Trenton contrasts strongly with the
great development of these animals in Minnesota and elsewhere in the United States

[p. 175].

Most of the fossils upon which Schuchert’s studies were based are
in the collections of the United States National Museum, and the
opportunity is thus afforded of comparing them directly with other
Ordovician faunas and of making more detailed correlations. The
results of a second study of these northern faunas lead to the follow-
ing conclusions:

(1) It is improbable that Utica strata occur in the far north, since
the only fossil noted of any value in making such a correlation is
Triarthrus becki, which is now known to occur also in the oldest
Trenton. Of course it is possible that an arm of the sea extended
northward during Utica time and allowed the deposition of these
particular strata.

(2) The Trenton age of the principal Ordovician deposits was
determined by Schuchert by the percentage composition method.
He found that of the 72 species known from the Silliman’s Mount
locality, 54 were common to other areas. Comparing these 54 with
known horizons in Minnesota, it was found that 10 occur in the Low-
ville, 17 in the Black River, 38, or about 70 per cent, in the Trenton,
and 11 in the Cincinnatian. This prevalence of Trenton species
seemed to be a good indication of the presence of a single fauna of
that particular age. However, this method of correlation is open to
some objections and has often been the occasion of error. In this
particular example, the fossils were derived from the débris of a con-
siderable thickness of strata, and there is just as much if not more

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 35

reason for believing that the Lowville, Black River, Trenton, and
Richmond rocks are actually present in the section as for assuming
that only Trenton strata occur. The former view is strengthened
by the unquestioned stratigraphy of areas further south and west.
Ulrich’s identification of recent collections made by Kindle in Alaska,
has shown the occurrence of a Black River fauna followed by a coral
fauna of Richmond age. In Manitoba and elsewhere in Canada, the
early Trenton strata (Maclurea bed) are succeeded by the Earliest
Silurian Richmond group. The same succession of Richmond strata
upon Trenton or older rocks is present in various parts of the Rocky
Mountain area of the United States, especially in the Big Horn Moun-
tains, and even as far south as El Paso, Texas. The most prevalent
zone of the Richmond group contains numerous corals of Silurian
genera; Halysites, Lyellia, Plasmopora, and Calapecia. This is the
same fauna noted on other pages of this work as present in the upper
Lyckholm and Borkholm limestone of Baltic Russia. The 11 ‘‘Cin-
cinnatian’’ species recorded by Schuchert from Silliman’s Mount
includes this same coral fauna, and it therefore seems certain that
the Richmond group is represented in the section. The Richmond
age of these corals was further evidenced by the fact that two very
characteristic brachiopods, a variety of Platystrophia acutilirata and
of Plectambonites sericeus came to light when I carefully searched a
fragment of limestone adhering to one of the corals. This particular
variety of Plectambonites is highly characteristic of the Richmond in
America and Europe. It is distinguished by the occurrence of small
teeth along the edge of the cardinal area of the dorsal valve.

The 38 strictly Trenton species, when compared with Minnesota
faunas, are found to be characteristic of the Clitambonites, Nemato-
pora, and Maclurea beds of the Minnesota-lowa composite section,
or, in other words, probably occur in strata equivalent to the early
Trenton (Stewartville and Prosser limestone) of the more southern
area. The species of Fusispira, Maclurea, Maclurina, Receptaculites,
Ischadites, and other genera listed by Schuchert as occurring in the
Suliman’s Mount fauna, and elsewhere only in the Minnesota Trenton,
are associated with a gray, fine grained rock which, when carefully
prepared, furnished asmall fauna of Ostracoda including a Leperditia
with Trenton affinities, but more especially the two bryozoans char-
acteristic of the Nematopora bed in Minnesota, Nematopora ovalis
Ulrich and Pachydictya pumila Ulrich.

Concerning the occurrence of Lowville limestone at Silliman’s
Fossil Mount, the evidence is not as conclusive as that for the Lower
Trenton and Richmond divisions, indeed, it is probable that only the
equivalent of the Decorah shale is present since the 10 Lowville
species listed by Schuchert occur also in that formation. Schuchert’s
list, however, shows enough characteristic Black River species to

36 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

make it certain that some part of this group is represented in the
section. Many of the specimens of these particular species show a
slight difference in color and preservation from the Trenton forms
discussed above. The more recent study of this Baffin Land fauna
disclosed the presence of at least six species of Bryozoa, so that the
remarks above concerning the practical absence of these forms are
less to the pomt. Indeed, it is believed that the bryozoans are
present, but because of their uninteresting aspect to the usual student,
were not collected.

Summing up, it seems probable from Schuchert’s results, combined
with the more detailed correlations of the present paper, that the
geologic section at Baffin Land consists of Black River strata resting
upon the old crystalline rocks, followed by an early Trenton forma-
tion equivalent to the Stewartville and Prosser limestones of Minne-
sota, and this in turn succeeded unconformably by the widespread
coral zone of the Richmond group. The same succession of strata,
so far as the Trenton and Richmond divisions are concerned, is present
on Akpatok Island, near the south shore of Hudson Strait, where the
species listed below were collected. Those marked with an asterisk
are characteristic Richmond forms, while the remaining refer to
Trenton and possibly Black River species: ~

Receptaculites oweni Hall. Orthis (Dinorthis) meedsi arctica Schuchert.
*Streptelasma robustum Whiteaves. Orthis (Hebertella) bellirugosa (Conrad).
*Calapecia canadensis Billings. Orthis (Dalmanella) testudinaria (Dalman).
* Rafinesquina lata Whiteaves. Platystrophia biforata (Schlotheim).
*Leptena unicostata (Meekand Worthen). | ?Rhynchotrema inequivalvis (Castelnau).
Plectambonites sericea (Sowerby). Cyrtoceras manitobense Whiteaves.

Orthis tricenaria Conrad. ,
STRATIGRAPHIC CORRELATIONS.

The exact position within the Ordovician system of the Russian
formations under discussion can be determined only by comparison
with sections in other parts of the world. The Baltic section has rather
generally been regarded, especially by European geologists, as an
- excellent illustration of continuous sedimentation from some time
in the Cambrian on well into the Silurian. The error of this view
must be apparent to all who will compare the Baltic sequence with
the much greater development of corresponding parts of the geo-
logical column in America. The exceeding inadequacy of the Baltic
section as the type for the Hopaleozoic is graphically shown in the
accompanying correlation table.

In the foregoing pages I have attempted to show (1) that, judging
from the bryozoan faunas, the strata ranging from the Glauconite
sandstone to the Wesenberg should be correlated with the American
Black River; (2) that the Wesenberg and early Lyckholm show

_ EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 87

affinities with the early Trenton; and (3) that the upper Lyckholm and
Borkholm closely resemble certain divisions of the Richmond group,
relations more definitely indicated on the correlation table. I have
also pointed out that there is a striking similarity in the lithology of
several of the corresponding formations in Russia and America. This
resemblance, as also the faunal similarity, is particularly notable in
comparing the Baltic succession with the section in central and
northern North America.

Finally, from a study of the lists given on pages 19 to 25, it will
be evident that there are comparatively few fossils of other classes
than the Bryozoa and corals common to the two areas. The reasons
for this unequal community of species are perhaps to be sought in
natural and inherent differences in modes of dispersal pertaining to
the several classes. While it is possible that I have recognized too
many species of Bryozoa as common to the two areas, it is to be said,
on the other hand, that my specific work has been checked up by the
foremost authority on fossil Bryozoa. Furthermore, specific discrimi-
nation has been carried to a greater degree of refinement than ever
before attempted, and this refinement naturally affects all the species.
If the species had been less closely drawn, a much greater percentage
of those common to the two areas would doubtless have resulted.
Respecting the other classes the possibility is recognized that future
and similarly close comparative study will show a decidedly greater
community of species, but it seems altogether unlikely that the per-
centage will ever approximate that attained by the Bryozoa.

BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

38

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EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

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Sith) BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The foremost American students of paleontology and paleogeog-

raphy have recognized three major faunal realms in the Northern —

Hemisphere, each of which was a center of development and dispersal.
These three realms are, first, the Atlantic; second, the Arctic; and,
third, the Pacific. Whenever opportunity offered, the faunas of one
or more of these oceanic basins invaded the submerged portions of
the continent. Most frequently but a single fauna occupied the
interior of the continent; occasionally faunas from two of the major
regions of dispersal were present, and rarely all three may have been
represented contemporaneously. For North America the South
Atlantic center of dispersal was probably the most important, at

Fic. 2.—MApP OF THE NORTH POLAR REGION, SHOWING DISTRIBUTION OF SILURIAN STRATA IN NORTH
AMERICA AND NORTHERN EUROPE, WITH THE HYPOTHETICAL SHORE LINES. (AFTER WELLER.)

least in earlier and middle Paleozoic times, with the Arctic center
second in importance. The Ordovician and Silurian faunas of the
Baltic region and the central and northern parts of North America
have so much in common that it seems probable they were all derived
from the Arctic region, from which, whenever the opportunity
afforded, they migrated into the adjacent continental areas. The
identity of the middle Silurian faunas of North America and northern
Europe has been established by Weller (fig. 2), but the earlier Silu-
rian and Ordovician faunas have not hitherto been believed to show
any similar community. This belief may rest on the fact that the

EL EIT TOTO IE OLE OTE IW NIE 33

np eeeri-

EARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 41

classes of organisms which require a shore line for migration have
been most studied in the two areas and sufficient resemblances
between them have not been noted. The types which are less de-
pendent on continuity of shore line are the corals, crinoids, ostracods,
and bryozoans, and these show the greatest similarity in the two
areas. The trilobites, gastropods, and other classes usually requiring
such a shore line only occasionally exhibit identical species. Some
of their species suggest forms of the Mississippi Valley, but as a rule
these faunas are strange to the American paleontologist and would
serve very poorly for exact correlation with the American strata.
However, the classes to which a shore line is not essential for migra-
tion show numerous species in common. ‘Thus, the bryozoans, which
in the Baltic area have received comparatively little attention, show
as a result of the present study that 65 species out of 161 are common
to this region and to America.

In correlating the Russian strata, hitherto referred to the Ordo-
vician, with only middle Ordovician and early Silurian strata of
America, other factors than faunal similarity must be considered.
According to the correlation table on page 38 all strata of Chazyan,
upper ‘Trenton, and of Cincinnatian time are unrepresented in the
Baltic section if the presence of numerous identical species is to be
counted a good eriterion in correlation. Excepting the long-lived
Corynotrypa delicatula and a few other cyclostomatous bryozoans, so
far as America is concerned, not a single species of the numerous
Mohawkian bryozoans is known in the underlying formations. Simi-
larly, the upper Trenton and Cincinnatian strata contain no species
of bryozoans in common with the underlying early Trenton and older
rocks. With the large number of species that has been described,
this is most conclusive evidence for the distinctness of the faunas
and upon these data alone the correlation of the Russian strata here
advocated would be justified.

The Black River strata containing the greatest percentage of Rus-
sian species are thickest in the northern part of North America and
overlap to extinction southward. For example, the southernmost
outcrops of the Decorah shale are in northern Tennessee where they
occur very locally overlying the Lowville limestone and are here
never over a few feet in thickness. Similarly, the lower Trenton
horizon designated as the Clitambonites and Nematopora beds in my
section on a previous page, overlap southward until in southern Ten-
nessee, where they rest upon the Lowville limestone, they are only
a few inches in thickness. Besides this, there is diastrophic evidence
that the seas of this time entered the continent from the north.
In Russia, on the other hand, we have no stratigraphical evidence
of corresponding overlaps of Ordovician strata upon any rocks
younger than the Dictyonema shales.

49 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Possibly future researches will reveal localities where the Glauco-
nite sandstone and overlying strata rest upon rocks younger than
the Dictyonema beds, which may be correlated with the American
Chazyan, and thus afford physical as well as faunal proof of the age
of the Russian beds.

It is of course possible that the lower part of the Russian section
succeeding the Dictyonema shale should be correlated with the
American Chazyan. The Russian faunas from B1 to the upper part
of F1 are remarkably uniform in character, changing only with the
introduction of new species. They seem to have developed almost
continuously, the few breaks in the sequence being of minor impor-
tance. As these faunas are limited to northern areas, their center of
origin and dispersal was undoubtedly the Arctic Ocean, from which
they invaded whenever opportunity offered. Itis perhaps impossible,
as yet, to fix the date of their origin, consequently we can not prove

that they did not tenant the Arctic Ocean and possibly invaded the ~

Baltic Basin as early as Chazyan time. Nor is it improbable that
they continued existence in these northern provinces even to the
close of the Ordovician. However, in the absence of definite evi-
dence tending toward such conclusions we are obliged provisionally
to rely on faunal similarity with the standardized American sequence
in determining the relative ages of the Russia Ordovician formations.

Respecting the upper part of the Baltic section, comprising the
upper Lyckholm and Borkholm, the range of possible error in corre-
lation with American deposits is much narrower and the problem on
the whole much less involved. As shown on page 35, the highly
characteristic Borkholm coral fauna is well developed in Arctic
America. Here it follows immediately on beds containing faunas
comparable with those found in Russia in a similar position with
respect to the upper Lyckholm and Borkholm. It was also shown
that these lower beds are strictly equivalent and presumably con-
temporaneous with the Black River and early Trenton formations in
the upper Mississippi Valley. As the middle Ordovician position of
these American strata is unquestionably established, a similar assign-
ment of their Russian equivalents seems, at least for the present,
justifiable.

In the more southern portions of Canada and in the United States
the coral zone of the Lyckholm-Borkholm is recognized at many
localities. It is well developed in the so-called Noix odlite of Mis-
souri and Illinois, which holds not only the same genera, but in many
cases identical species of corals with distinct Silurian affinities. This
odlite, as well as the underlying formations of Richmond age, contain
the bryozoans which have been noted also in the upper Lyckholm
and in the Borkholm formations. Though similar to the preceding

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 43

Ordovician faunas in Russia and Arctic America, of Arctic origin and
development, the upper Lyckholm-Borkholm fauna is more sharply
distinguished from the lower Lyckholm and preceding faunas than the

DURING BLACK RIVER (DECORAH) AND EARLY TRENTON (PROSSER) TIMES. ACTUAL OUTCROPS SHOWN
IN BLACK.

latter are from each other. This fact offers another argument for
the belief that a line passes through the Lyckholm that represents a
very considerable time break and adds to the plausibility of the cor-
relation of the Wesenberg as not younger than early Trenton.

92602°—Bull. 77—11 5

44 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

On the accompanying paleogeographic map (fig. 3) I have plotted
all of the localities discussed in the preceding pages as well as other
areas where Black River and early Trenton strata are known to
contain the faunas under discussion. Except for local variations of
minor importance the distribution of these two formations in America
is essentially the same, so that this map will serve for both. Although

Bathymetrical Chart
of

Sea Level to 200M Fa Neng NORTH POLAR
(ed SEAS

200Hto1000% > fy Fridtjof Nansen

NE SDE
Aap
am]

Fic. 4. BATHYMETRIC CHART OF THE NORTH POLAR SEAS, SUGGESTING ROUTES OF MIGRATION FOR MARINE
ORGANISMS. (AFTER NANSEN:)

the Ordovician rocks of the Baltic area fail to outcrop some distance
east of St. Petersburg, due perhaps entirely to overlap by younger
strata, they may extend across northern Russia under cover, for
outcrops are known in the Ural Mountains and along the shore of the
Kara Sea. The latter locality is of particular interest in the present
connection, for here, along the shores of Yugor Strait, Nansen

an ae

—————————— ee

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 45

collected a fauna which Kiaer ‘ correlated with the Baltic C1. With
such an eastward extension of the Baltic Ordovician faunas, it is
quite possible that in time they may be proven to be circum-polar.
East of the Ural Mountains and west of Alaska little of the Ordovician
geology is known, so that here, in drawing the outlines of the Black
River-Early Trenton Sea, I have simply followed the present day
coast.

In this connection Nansen’s bathymetric chart of the North Polar
Seas, which I have introduced (fig. 4), is of interest in showing possi-
ble routes of migration for marine faunas. Believing in the perma-
nence of continental land masses and oceanic deeps, it is thought that
essentially similar conditions prevailed in early Paleozoic times.

THE BRYOZOAN FAUNAS.

Although the bryozoans in many instances constitute the larger
portion of a fauna, the study given them is almost invariably less
than that of any other class. This is due to the fact that they have a
reputation for being one of the most difficult classes of organisms.
Their small size requires the use of a hand lens or a microscope, and
in the fossil forms frequently the preparation of thin sections. Yet
the necessity for thin sections is to the advantage of the student, for
by their use he is less liable to error. It is in this very fact that the
fossil Bryozoa are so valuable to the stratigrapher. In areas where
other fossils are too imperfect or ill preserved for identification, the
merest fragments of bryozoans can be identified with certainty by
properly prepared thin sections. Again, the bryozoans are of great
importance to the stratigraphical geologist because they occur
usually in great abundance over wide areas and preserve their specific
characters with little change.

Of the various classes that are represented in the Ordovician rocks
of Baltic Russia, bryozoans in all probability rank first in number of
species and individuals. As indicated on some of the plates at the
end of this volume, certain shales are often crowded with them and
thin limestone bands are frequently one mass of their fragmentary
remains.

All of the trepostomatous bryozoans and many of the Cryptos-
tomata and Cyclostomata require thin sections for their initial study.
Directions for the preparation of such thin sections have been given
in the report of the ‘‘Geological Survey of Illinois,” volume 8, 1890,
page 292; in the ‘Final Report of the Geological and Natural History
Survey of Minnesota,” volume 3, 1893, page 100; in ‘‘Bulletin 173 of
the United States Geological Survey,” 1900, page 122, and, more
recently, in the ‘‘Thirty-second Annual Report of the Indiana

1J. Kiaer in Nansen’s North Polar Expedition, vol. 4, No. 11, 1902.

46 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Geological Survey,’’ 1907, page 736. As detailed directions are given
in each of these volumes, it is unnecessary to repeat them here.

It is of course needless to make thin sections of every specimen.
After a species has been determined, the internal characters of other
specimens believed to belong to the same species can be determined
by slightly etching with acid whatever parts one wishes to study,
and, after moistening the etched areas, examining them under a
hand lens. With this very simple method, the structural details can
be seen distinctly. Comparison then with sectioned material or with
species which have been described and figured will in most cases
serve to establish the identity of the specimen.

Most of the terms employed in the description of fossil bryozoans
are defined in the following notes on terminology:

TERMINOLOGY.

Zoarvum.—The composite structure formed by repeated gemma-
tion. Although fairly constant for each species, the form which
results is very variable. Gemmation in a plane produces unilamimar
sheets, which are sometimes free, but are often parasitic Gncrusting)
upon other organisms; in the former case the protecting covering on
the under side is the epitheca. Hollow branches lined with an
epitheca are a special form of this mode of gemmation. Two
unilaminar sheets growing erect, back to back, form a bilaminar or
bifoliate expansion or frond. The epithece of the two layers of
zocecia thus brought together form a mesotheca (mesial or medial
lamine). The small pores seen in the mesotheca, or between the
walls of adjoining zoccia of certain species when thin sections of
well-preserved specimens are examined under the microscope, have
been given the name of median tubult by Ulrich.

Zowecium.—The cavity inhabited by the animal. The bounding
wall is constructed of laminated tissue. In particularly well-pre-
served specimens, thin sections reveal very small tubular passages
penetrating the walls of adjoining zocwcia. To these Ulrich has
applied the name communication pores. As will be noted in the
descriptions of certain species in this work, the Ceramoporide show
especially well-marked pores of this nature.

In some forms, especially among the Trepostomata, the zoccia
have the form of elongated tubes, which are crossed by partitions
termed diaphragms. The general term tabule is sometimes em-
ployed in place of diaphragms. The opening upon the surface of the
zocecium or of the vestibule among the Cryptostomata is the aper-
ture. Itis often closed by a zowcial cover (closure or operculum).

One side of the zoecial cavity in some of the Trepostomata is lined
with a series of superimposed vesicles, the cystuphragms; their purpose
or use is unknown.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 47

Among the Cryptostomata plates frequently project from the walls
into the cavity; that upon the posterior wall of the zocwcium is the
superior hemiseptum, that upon the outer wall the inferior hemiseptum.
The opening of the zocecium among the Cryptostomata is the orifice;
the tubular shaft which is left above the orifice as the surface of the
zoarium is thickened by strengthening or protective tissue is the
vestibule.

Macule.—A common surface character among a large number of
Paleozoic bryozoans and many more recent species is the occurrence
at regular intervals of areas made up of larger zocecia and more
numerous mesopores, or of mesopores alone. ‘These areas or spots
of special development are designated under the general name of
maculz. When the macule are elevated, they are known as monti-
cules or tubercles, according to the sharpness of elevation.

Mesopores (interstitial cells). —Tubular structure occurring between
the zocecia; they are usually smaller than the zocecia and are angular
or irregular in outline in cross sections. The number and size of the
mesopores varies greatly sometimes even in the same species. If
diaphragms are present they are invariably more abundant in the
mesopores, thus affording a ready means of discriminating between
the zocecia and mesopores. The development of mesopores is prac-
tically restricted to the peripheral portion of the zoarium and their
use simply to fill up whatever spaces were left between the zowcia.
Mesopores are, therefore, simply cells filling the interzocecial spaces.

An interesting development of mesoporelike cells has been noted
in many of the Russian massive bryozoans, such as Diplotrypa bicornas,
Esthoniopora communis, and Dianulites petropolitana. In old exam-
ples of these species the basal portion of the zoarium shows no true
zocecia, but in their place are numerous thick-walled, closely tabulated,
mesoporelike cells. With age more and more tissue is deposited
upon the walls until finally the openings of the mesopores are prac-
tically obliterated. Possibly the zoarium of such massive species
rested in muddy deposits during life, and normal zoecia developed
only where a food supply was available. The Russian specimens of
Leptoirypa hexagonalis which have been invariably found incrusting
a species of Hyolithes likewise develop a basal layer of such thick-
walled mesopores. In every case this layer is found only on the flat
side of the Hyohthes. Other species which incrust Hyolithes, such as
Mesotrypa expressa, likewise show this layer only on the flat side of
the shell. If this layer of smaller cells is developed only on the basal
portion of the zoarium, its occurrence on the flat side of .the Hyolithes
is probably indicative that the bryozoan attached itself to only dead
shells which would naturally drop to the bottom flat side down.

Interspace.—The part of the surface of the zoarium between the
apertures of the zocecia.

48 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Vesicular tissue-—In a number of forms the space between the
zocecia is occupied by tissue composed of irregularly superimposed
vesicles. This probably served to give strength to the zoarium and
to protect the zoccia.

Acanthopores.—Small cylindrical tubes usually situated at the
angles of junction of adjoining zoecia, forming spinelike projections
upon the surface. Thin sections show that the acanthopore is not a
mere surface ornament but is a tube inclosed in the wall substance of
the zocecium and developed generally only in the mature region.
This tube, with its inclosing wall substance, sometimes reaches a size
as great as that of the ordinary mesopore.

Lunarium.—iIn the Ceramoporide and Fistuliporide especially,
the posterior portion of the zocecial wall is more or less thickened and
elevated above the general surface and curved to a shorter radius to
form the crescentic structure known as the lunarium.

BIBLIOGRAPHY.

Although the list of articles dealing with the Russian Ordovician
Bryozoa is not a small one, practically all of value that has been pub-
lished is contained in Dybowski’s “ Chaetetiden der Ostbaltischen Silur-
Formation” and in Eichwald’s ““Lethza Rossica.” As neither of these
works is easily obtained, the illustrations and some of the observa-
tions of both authors have been incorporated in the present work, in
the effort to embody in this volume all available information regarding
the subject. The following list is believed to contain most of the
publications referring to the Russian Ordovician Bryozoa:

LIST OF PUBLICATIONS.

1825. Ercawautp, Epouarp von. Geognostico zoologicee per Ingriam marisque Bal-
tici provincias nec non de Trilobitis observationes.

1829. Zoologia Specialis, vol. 1, pp. 179-189, 198-201, pls. 2, 3.

1830. PanpER, C. H. Beitrag zur Geognosie d. Russlands.

1833. Gotpruss, Aucust. Petrefacta Germanie, vol. 1, pp. 23-41, pls. 8-12.

1837. Kuroraa, 8. Zweiter Beitrag zur Paleontologie und Geognosie Dorpats.

1840. Ercowatp, Epovarp von. Uber das Silurische Schichtensystem von Esth-
land.

1840-1842. Die Urwelt Russlands durch Abbildungen erlfiutert, pt. 1, pp.
1-106, pls. 1-4; pt. 2, pp. 1-184, pls. 14.

1842. Kurorea, S. Verhandlungen der mineral Gesellschaft zu St. Petersburg.

1845. LonspaLe, Wittiam. Description of some characteristic Paleozoic Corals of
Russia, in Verneuil and Keyserling’s Geology of Russia in Europe and the
Ural Mountains. [Bryozoa, pp. 626-632. ]

1846. Keysertinc, ALEXANDER VON. Wissenschaitliche Beobachtungen auf einer
Reise in der Petschora-Lande im Jahre 1843.

1851. Mine-Epwarps, Henri, and Hare, Junes. Monographie des polypiers fos-
siles des Terrains Palaeozoiques.

1854.

1856.

1858.

1860.

1860.

1877.

1879.

1881.

1900.

1902.

1905.

BARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 49

EicHwaLD, EpouarRD von. Die Grauwackenschichten yon Liv- und Esth-
land. Bulletin de la Société Imperiale des Naturalistes de Moscou, vol. 27,
pp. 86-89.

Beitrag zur geographischen Verbreitung der fossilen Thiere Russlands.
Bulletin de la Société Imperiale des Naturalistes de Moscou, vol. 29, pp. 91-96,
448-466.

Scumipt, FrrepERIcCH von. Untersuchungen tiber die silurische Formation
von Esthland, Nord-Livland und Oesel. Archiv ftir Naturkunde Liy-, Esth-
und Kurlands, vol. 2, ser. 1, pp. 1-247, 465-474.

EicHwaLp, EpovarpD von. Lethea Rossica, vol. 1, Ancienne Periode, pp.
355-419, 434-435, 450-452, 475-494, pls. 23-28.

Mrnz-Epwarps, Henri. Histoire naturelle des Coralliaires ou polypes pro-
prement dits, vol. 3.

DysowskI, Wiapistaw. Die Chaetetiden der Ostbaltischen Silur-Formation,
134 pp., 4 pls.

NicHoutson, H. AtLEynE. On the structure and affinities of the Tabulate
Corals of the Paleozoic period, with critical descriptions of illustrative species,
342 pp., 15 pls. [Bryozoa, pp. 253-327, pls. 12-15.]

On the structure and affinities of the genus Monticulipora and its sub-
genera, with critical descriptions of illustrative species, 240 pp., 6 pls.

Nickses, Joun M.,and Basster, R.S. A Synopsis of American Fossil Bryozoa.
Bulletin 173, U. S. Geological Survey, 663 pp.

Wian, Cart. Uber die Borkholm Schicht im Mittelbaltischen Silurgebeit.
Bulletin of the Geological Institution of the University of Upsala, vol. 5,
pt. 2, pp. 149-222, pls. 5-8.

Lamansky, W. Die Aeltesten Silurische Schichten Russlands (Etage B). Me-
moires du Comité Géologique, St. Petersburg, vol. 20.

RANGE OF BALTIC ORDOVICIAN AND EARLY SILURIAN BRYOZOA.

In the following table I have arranged all of the species recognized
as valid in the present volume in biologic order, and have indicated
their geologic range in both Russian and American formations. The
latter are abbreviated as follows:

Platteville = P; Cltambonites = C; Stictoporella = St; Nemato-
pora=N; Rhinidictya=R; Fusispira=F; Ctenodonta=Ct; Rich-
mond=R; Phylloporina=Ph; Clinton=Cl.

BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

50

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54 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.
DESCRIPTIONS OF GENERA AND SPECIES.
Order CTENOSTOMATA Busk.

The Paleozoic fossils referred to this order of the Bryozoa have
been made the subject of a small monograph‘! to which the reader
is referred for a more detailed discussion than can be given at present.
As remarked in that work, little is known about these peculiar types
of fossil Bryozoa, and, while their classification with the Ctenostomata
is perhaps a little better than a mere working theory, it rests mainly
on highly suggestive resemblances between the fossil organism and
the supposed corresponding parts of living forms, and on conjectures
as to the unknown parts. Again, their reference to the Ctenostomata
is supported by more and stronger arguments and opposed by fewer
objections than when comparison is made with any other class of
organisms. As these fossils are comparatively rare in American
strata, which have been searched quite thoroughly for them, it is
not surprising that only a few specimens have been found in the
Russian and Swedish deposits. However, the few examples that
have appeared in the various collections studied have been fairly
well preserved and their identification with American forms can be
made with a correspondingly greater degree of certainty.

With a possible exception, the various species referred to as Paleo-
zoic Ctenostomata have been thought to be founded upon the creep-
ing bases of the zoarium and not upon the zocecium itself. The pos-
‘sible exception was in the case of Rhopalonaria in which it was
assumed that the fusiform swellings are really the zocecia instead of
the creeping base. The zoccia in both Rhopalonaria and Vinella
were probably deciduous and were developed by budding from these

ores.

i The chemical composition of the zoarium of the recent Ctenosto-
mata and of their supposed fossil representatives does not entirely
agree, although in each instance it differs from that of the other orders
of Bryozoa. In the recent Ctenostomata the zoartum is horny or
membraneous. The Paleozoic representatives contain more cal-
careous matter, although a considerable portion of their constitution
is corneous and shows a style of preservation quite unlike that of
associated bryozoans. Quite frequently these fossil forms have been
so changed that their substance now occurs as black and corneous,
or is replaced entirely by iron pyrites.

The Ctenostomata may be briefly defined as follows: Zoccia
usually isolated and developed by budding from the internodes of a
distinct tubular stolon or stem. Orifice terminal, with an operculum
of sete. Zoaritum horny or membranaceous. Marsupia wanting.

1 Ulrich and Bassler, Smiths. Misc. Coll., vol. 45 (Quart. issue, vol. 1, pts. 3 and 4), 1904, pp. 256-294, pls.
65-68.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 55
Family VINELLID Ulrich and Bassler.

All of the forms referred to this family are fossil and are believed
to represent merely the creeping base of the zoarium. This base
consists of simple, delicate, partially ramifying, tubular threads,
which, in one genus, are arranged without any regular order, in a
second proceed from more or less definite centers, and in a third are
locally jomted. The second of these, Vinella, is represented in the
collections under study by its type species, Vinella repens, while the
first is recognized very doubtfully for the reception of a very inter-
esting new form, Heteronema priscum.

Genus VINELLA Ulrieh.!

' Vinella Utricn, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p. 173.—MiILuER,
North Amer. Geol. and Pal., First App., 1892, p. 685.—Vine, Proc. York-
shire Geol. Polyt. Soc., vol. 12, 1892, p. 84.—Utricu, Geol. Nat. Hist. Surv.
Minnesota, vol. 3, pt. 1, 1893, p. 112.—Poora, Syst. Sil. Centre Boheme, vol.
8, pt. 1, 1894, p. 17.—Simpson, Fourteenth Ann. Rep. State Geologist New
York for the year 1894, 1897, p. 604.—NicKLEs and Basser, Bull. 173, U.S.
Geol. Surv., 1900, p. 19—Utricu and Basster, Smiths. Misc. Coll., vol. 45,
1904, p. 273.— Basser, Bull. 292, U.S. Geol. Surv., 1906, p. 12.

Zoarium parasitic, consisting of very slender, tubular threads or
stolons, arranged more or less distinctly in a radial manner. Surface
of threads with a single row of small pores. These may be wanting
locally, and vary considerably in the degree of their separation.
Zocecia unknown, probably deciduous.

Genotype.— Vinella repens Ulrich. Middle Ordovician of America
and Europe.

VINELLA REPENS Ulrich.

Text fig. 5.

Vinella repens Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p. 174,
fig. 1—Vinz, Proc. Yorkshire Geol. Polyt. Soc., vol. 12, 1892, p. 84, pl. 3,
figs. 14.—Utricx, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893,
p. 114, pl. 1, figs. 1-5.—Simpson, Fourteenth Ann. Rep. State Geologist New
York for the year 1894, 1897, p. 604, fig. 222 —U.ricu and Basser, Smiths.
Misc. Coll., vol. 45, 1904, p. 274, pl. 68, figs. 1-3.

Original description.—Zoarium repent, the stolons delicate, thread-like, often longi-
tudinally striate, straight or flexuous; from 0.06 to 0.11 mm. in diameter; bifurcating
often and sometimes arranged in a radial manner about a central node. Where best
preserved, very small pores arranged uniserially along the center of the upper surface
of the threads; about 11 in 2.5mm. Zocecia unknown, probably deciduous.

Three specimens of this species have been identified in the Russian
collections, one from the Jewe limestone (D1) incrusting a ramose
bryozoan, and two from the Wesenberg limestone (E) growing upon

1 In the synonymy throughout this work, only those references deemed of importance to the student in
the present connection are given. More complete citations can be found in Bull. 173, U. S. Geological
Survey.

56 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

brachiopod shells. Although all three are in a fair state of preserva-
tion, they add no new features to the original description given above.

Vinella repens is a characteristic Black River fossil in America,
and the occurrence of such typical examples of the species in the
same general horizon in Russia is only another instance of the strati-
graphic value of these delicate bryozoans. The fine radiating threads
of this species are so different from any other associated bryozoan
that comparisons are unnecessary. Usually the preservation is by

Fig. 5.—VINELLA REPENS. @, TWO COLONIES, NATURAL SIZE, ATTACHED TO THE INNER SIDE OF A VENTRAL
VALVE OF STROPHOMENA SEPTATA; 0, PORTION OF ONE OF THE COLONIES, X18. THE PORES ARE ABSENT,
PROBABLY NOT HAVING BEEN PRESERVED; c, ANOTHER PORTION OF SAME ZOARIUM, X18, SHOWING A
NUCLEUS WITH FIVE DIVISIONS OF THE TUBULAR STOLON RADIATING FROM IT. THIS PORTION OF THE
SPECIMEN ALSO PRESERVES SOME OF THE PORES MARKING THE POINTS WHERE THE ZOGCIA WERE ATTACHED,
d, ANOTHER SPECIMEN, NATURAL SIZE, ATTACHED TO A FRAGMENT OF SHELL}; €, SMALL PORTION OF SAME,
X18, WITH THREE TUBES LYING PARALLEL WITH EACH OTHER. ‘THE LONGITUDINAL LINES ARE STRONGER
THAN USUAL. PHYLLOPORINA BED OF BLACK RIVER (DECORAH) SHALES AT ST. PAUL, MINNESOTA.
(AFTER ULRICH.)

the black iron pyrites, which gives a clue in the identification of poor
specimens.

Occurrence —Not uncommon in the Phylloporina bed of the Black
River (Decorah) shales in Minnesota. Less common in the Jewe
limestone (D1) at Baron Toll’s estate (Cat. No. 57507, U.S.N.M.),
and in the Wesenberg limestone (EZ) at Wesenberg, Esthonia (Cat.
No. 57179, U.S.N.M.).

Typical American specimens of this species are in the collections of |
the British Museum.

HARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 57

Genus HETERONEMA Ulrich and Bassler.

Heteronema UnRicu and BassieR, Smiths. Misc. Coll., vol. 45, 1904, p. 278.

Original description.—Zoaria, so far as known, consisting of usually simple, or
locally jointed, delicate, sparsely ramifying, tubular, creeping threads, arranged
without apparent order. Pores rarely observed, apparently always in a single row.

Genotype.— Heteronema capillare Ulrich and Bassler. Silurian, isl-
and of Gothland.

The species referred to this genus represent the simplest forms of
the Vinellide and are distinguished from the type genus Vinella first
because of this extremely simple structure, but mainly on account
of the absence of the highly characteristic nuclei and consequent
radial arrangement of the threads. The following new species forms
such a regular network by dichotomous branching that it must be
doubtfully referred to Heteronema. A species from the Upper Ordo-
vician (Maysville formation) of Ohio has a somewhat similar growth,
and it is possible that with more knowledge these two will be
referred to a new genus. H. priscwm is of further interest in that
it is the oldest known bryozoan. The Ctenostomata are usually con-
sidered the simplest of bryozoans, and theoretically species of this
order should obtain in. the oldest rocks. The discovery of such a
simple type of the order in the Cambrian is therefore in keeping with
our knowledge of the class.

HETERONEMA PRISCUM, new species.
Text fig. 6.

This species is founded on a number of specimens, all of which
consist of large or small patches incrusting the smooth shells of the
brachipod Obolus. It was at first believed that these incrustations
represented a reticulate surface ornamentation, but this view was
soon disproved by the different composition of the threads and
mainly by the fact that in some specimens one set of threads was
growing over another.

The zoarium consists of thin, dark, corneo-calcareous threads bifur-
eating dichotomously so uniformly that a rather regular network
results. The individual meshes of this network average 0.4 mm. in
diameter, while the threads themselves are less than 0.02 mm. wide.
Frequently, as shown in figure 6 c, one zoarium may be noted grow-
ing over one or more previous incrustations. Upon examination
under a high power of the microscope small pores rather regularly
arranged are seen along the middle line of the threads, while the
zoarial substance itself appears very faintly granulose. The threads
are not always of uniform diameter and occasionally are somewhat
bulbous.

58 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

As noted in the general remarks upon the Ctenostomata, the refer-
ence of these fossil forms to that order seems the best arrangement
under the circumstances. In the case of the present species particu-
larly its unquestionable reference to the Bryozoa must be substan-
tiated by future discoveries.

NE
Fic. 6—HETERONEMA PRISCUM. @, A COLONY ATTACHED TO A VALVE OF OBOLUS, 4; b, A PORTION
OF THE SAME, X20, ILLUSTRATING THE METHOD OF BRANCHING; ¢, PARTS OF TWO COLONIES, X35, WITH
ONE GROWING OVER ANOTHER; d, SMALL PORTION OF ANOTHER ZOARIUM, X50, SHOWING THE MICRO-
SCOPIC STRUCTURE OF THE THREADS. UNGULITE SANDSTONE (A2), UPPER CAMBRIAN, JEGELECHT
FALLS, ESTHONIA.

Occurrence.—An abundant species in the Upper Cambrian (Ungu-
lite) sandstone (A2) at Jegelecht Falls, Esthonia.

Cotypes.—Cat. No. 57180, U.S.N.M.

British Museum collections, one specimen.

Order CYCLOSTOMATA Busk.

The bryozoans belonging to this order have a simplicity of struc-
ture highly characteristic in both zoaria and zoecia. The zocecia are
especially simple throughout the order, so that the classification is
based almost entirely upon their arrangement and method of growth.
The recent forms show that this same simplicity extends to the poly-
pide, and that the larve of the different families are practically
identical. The zocecia are simple, calcareous tubules with plain,
uncontracted, usually rounded apertures and with minutely porous
walls. The interzocwcial spaces may or may not be filled with solid
strengthening deposits. Marsupia and appendicular organs are want-
ing, but the ovicell is present in the form of a large cell or an inflation
of the zoarial surface set aside for reproductive purposes,

The simplest Cyclostomata are comprised in Busk’s families Diasto-
poride and Idmoneide and in the Entalophoride of Reuss, all of
which have numerous fossil species. Each of these families is rep-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 59

resented, although somewhat sparsely, in the Russian strata under
discussion.

The much-debated Ceramoporide and Fistuliporide are more
numerously represented both in genera and species. These families,
considered by many authors as tabulate corals but by Ulrich as
trepostomatous bryozoans, were doubtfully referred by the latter in
1900 * to the Cyclostomata. Further studies have shown the wisdom
of this course, and I believe enough evidence can now be assembled
to establish the Ceramoporide and Fistuliporide as undoubted
Cyclostomata. Both have the minutely porous wall structure of
typical members of the order, and, in addition, most of their genera
show ocecia exactly as in recent forms.

Family DIASTOPORID/ Busk.

Only the simplest of the diastoporoid genera are represented in
the Russian collections, and most of their species prove to be iden-
tical with American forms. The same condition holds for the
Idmoneide and the Entalophoride, but the remaining families, while
represented by the same genera, have in most cases new, although
analogous, species.

Genus STOMATOPORA Bronn.

Stomatopora Bronn, Pflanzenth., 1825, p. 27.—D’Orsteany, Pal. Francais, Terr.
Cret., vol. 5, 1854, p. 833.—Haime, Bry. Foss. Form. Juras., 1854, p. 159.
Stomatopora (part) Pictrt, Traite de Pal., ed. 2, vol. 4, 1857, p. 142.—Htncxs,
British Marine Polyzoa, 1880, p. 424.—Zirrez, Handbuch d. Pal., vol. 1,
1880, p. 598.—Uxricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p.
149.—VineE, Proc. Yorkshire Geol. Polyt. Soc., vol. 9, 1887, p. 186.—MimeER,
North American Geol. and Pal., 1889, p. 325.—Utricu, Geol. Surv. Illinois,
vol. 8, 1890, p. 367; Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
115; Zittel’s Textbook of Paleontology (Eng. ed.), vol. 1, 1896, p. 260.—
Smpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894,
1897, p. 597.— NickiEs and BassteEr, Bull. 173, U. 8. Geol. Surv., 1900, p.
20.—Cumines, Amer. Journ. Sci., ser. 4, vol. 17, 1904, p. 75; 32nd. Ann.

Rep. Dept. Geol. Nat. Res. Indiana, 1907, p. 757.
Aulopora (part) GotpFuss, Reuss, Hatz, NicHotson.

Zoarium of delicate, adnate, uniserially arranged, subtubular
zocecia with subterminal, exsert apertures and minutely porous walls.

Genotype.—Stomatopora dichotoma (lamouroux). Jurassic of
Europe.

Previous definitions of the genus Stomatopora have included the
simple unilinear species with clavate zoccia and with constricted
apertures. These have been recently classed under the new genus
Corynotry pa.”

1 Zittel’s Textbook of Paleontology, English edition. vol. 1, p. 267,
? Bassler, Proc. U. S. Nat. Mus., vol. 39, 1911, pp. 497-527,
92602°— Bull. 77116

60 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Species of Stomatopora have also been classed with the coral genus
Aulopora, which has a somewhat similar growth and cell aperture.
This coral, however, in addition to other differences, is invariably of
much larger size and lacks the porous walls of the bryozoan.

STOMATOPORA ARACHNOIDEA (Hall).
Text fig. 7.

Aulopora arachnoidea Hatt, Nat. Hist. New York, Pal., vol. 1, 1847, p. 76, text fig.,
pl. 26, figs. 6a-c.—NicHotson, Pal. Ohio, vol. 2, 1875, p. 216, pl. 23, figs. 1, 1b.

Stomatopora arachnoidea NicKLES and BassueER, Bull. 173, U. S. Geol. Surv., 1900,
p. 419.—Cumrines, 32nd. Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p.
885, pl. 32, figs. 2—2c.

The American specimens referred to this species occur in all the
divisions of the Middle and Upper Ordovician, and in the Richmond
group of earliest Silurian age. The various Russian examples having
the characters of typical
Stomatopora agree in all
respects with S. arach-
noidea, save that they
are of slightly more
delicate growth. This
difference is not even
of varietal importance,
since, as shown from
the study of American
examples, a large num-
ber of specimens would

Fic. 7—STOMATOPORA ARACHNOIDEA. @, PORTION OF A DELICATE undoubtedly remove it.
ZOARIUM, X9, GROWING UPON THE CELLULIFEROUS SIDE OF A The zoarium in
SPECIES OF HELIOLITES; 0, PART OF THE SAME, X20, ILLUS- 3
TRATING THE DETAILED STRUCTURE. LYCKHOLM LIMESTONE Stomatopora arachnoidea

(F1), HOHENHOLM, ISLAND OF DAGo. is of slender, delicate
incrusting, frequently dividing, more or less parallel edged branches
made up of simple zocecia arranged in a single series. The apertures
are circular, somewhat exsert, and are almost as wide as the branches,
4 to 5 in 2 mm.; walls of zoecia finely porous.

There is no chance to confuse this species with any associated
bryozoan, save, possibly, the various forms of Corynotrypa. The
latter agree in their simple, unilinear, adnate growth, but differ
decidedly in their club-shaped zoecia.

Occurrence—in America this species is found throughout the
Middle and Upper Ordovician and earliest Silurian at various local-
ities in the United States and Canada. The occurrences in Russia
are (1) in the Echinospherites limestone (C1), 4 miles east of Reval,
where a specimen was found incrusting a ramose bryozoan (Cat. No.
57182, U.S.N.M.); (2) a small example incrusting a crinoid plate in
the Kuckers shale (C2), Baron Toll’s estate, near Jewe (Cat. No. 57181,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 61

U.S.N.M.); and (3) several large colonies growing upon the cellulif-
erous face of Heliolites, from the Lyckholm limestone (F1), at Hohen-
holm, island of Dago, Baltic Sea (Cat. No. 57183, U.S.N.M.).
Numerous specimens from American localities are in the British
Museum.
Genus CORYNOTRYPA Bassler.

Corynotrypa BAsSsLER, Proc. U.S. Nat. Mus., vol. 39, 1911, p. 501.
Stomatopora (part) of authors.

This genus was recently instituted for the reception of species
hitherto assigned to Stomatopora, in which the zoarium consisted of
adnate, simple, subtubular zocecia arranged unilinearly but of a
distinctly oval-pyriform to elongate-clavate shape. The zocecium
is further distinguished by having its proximal end constricted and
united to the preceding zoceclum by a narrow stolon of variable
length; the distal portion of the zocecium is expanded and bears the
aperture which is subterminal, circular, and surrounded by a more
or less distinctly elevated peristome; zocecial walls, as in Stomatopora,
finely porous.

The points of agreement and difference between Stomatopora and
Corynotrypa may be easily discerned by comparing the illustration
of S. arachnoidea (fig. 7) with the views of (. delicatula and other
species figured on the following pages. In discriminating species
of Corynotrypa, the characters which have been found to be most
valuable are the size and shape of the zocwcium and its angle of
divergence obtained by measuring the rate of expansion of its sides,
beginning at the distal end of the stolon. The slender, tubular
connecting portion designated the stolon is the most variable of all
characters and is consequently of little aid in the separation of species.

Genotype.—Corynotrypa delicatula (James). Ordovician and early
Silurian of North America and Europe.

CORYNOTRYPA DELICATULA (James).
Text fig. 8.

Hippothoa delicatula JAMES, Paleontologist, No. 1, 1878, p. 6.

Stomatopora delicatula NicktEs and BasstER, Bull. 173, U. 8. Geol. Surv., p.
419.—BassuER, Proc. U. 8. Nat. Mus., vol. 30, 1908, p. 55, p!. 3, figs. 4-7.

Stomatopora proutana MituER, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p.
39, pl. 1, figs. 4-406.—Uxricu, Geol. and Nat. Hist. Surv. Minnesota, Final
Rep., vol. 3, pt. 1, 1893, p. 117, pl. 1, figs. 8-12.

Rhopalonaria pertenuis ULRicu, Fourteenth Ann. Rep. Geol. and Nat Hist. Surv.
Minnesota, 1886, p. 59.

Stomatopora tenuissima Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890,
p. 175, fig. 2; Geol. and Nat. Hist. Surv. Minnesota, Final Rep., vol. 3, pt. 1,
1893, p. 116, pl. 1, figs. 16, 17.

Stomatopora delicatula-tenuissima NickLES and BasstER, Bull. 173, U. 8. Geol.
Surv., 1900, p. 419.

Corynotrypa delicatula BAssuerR, Proc. U. 8. Nat. Mus., vol. 39, 1911, p. 506, text
figs. 3a, 4-7.

62 BULLETIN 17, UNITED STATES NATIONAL MUSEUM.

This neat, incrusting fossil is extremely abundant in America,
where it is known in most of the Ordovician formations, beginning
with the Stones River. Jn Russia, on the contrary, it appears to be
less common, although specimens have been found in divisions C2,
D1, and D3. The zoccia in the specimen from the Wassalem beds
are larger than in the more common form of the species and agree
exactly with examples from the lower beds of the Black River group —
of Minnesota and elsewhere. The other localities, however, afford
specimens of the more typical size, and the range in this respect is
therefore the same as in the American examples.

In both the large and smaller forms the zoarium is Incrustmg and
consists of uniserially arranged, slender, club-shaped zocecia, increas-

Fig. 8.—CORYNOTRYPA DELICATULA. SPECIMENS FIGURED BY ULRICH AS STOMATOPORA PROUTANA,.
@, FRAGMENT OF A ZOARIUM, X9; 6 AND c, TWO GROUPS OF ZOG@CIA, X 25; d, SEVERAL ZOGSCIA OF UN-
USUAL SIZE, X25. BLACK RIVER (DECORAH) SHALES, ST. PAUL AND MINNEAPOLIS, MINNESOTA. (AFTER
ULRICH.)

ing gradually in size from the narrow proximal end to the rounded
anterior portion. The aperture is small, subterminal, with a slightly
elevated border, and about one-third the diameter of the anterior
third of the zocecia. The measurements for the two forms are as
follows: Typical specimens have zocecia 0.04 mm. in diameter at the
proximal end, increasing to 0.12 to 0.15 mm. at the widest part of the
rounded anterior portion. The zocecia vary from 0.6 to 0.8 mm. in
length, and 8 to 10 occurin 5mm. The larger form varies from 0.8
to 1.1 mm. in length and from 0.2 to 0.3 mm. in diameter at the ante-
rior portion. The stolon is of variable length, as shown in figures
8a and 8c. The angle of divergence in both large and small zoccia
is about 15°.

While Corynotrypa delicatula is closely related to several American
forms, there is but one Russian bryozoan near enough to require
detailed comparison. This is C. barberi, occurring in the Lyckholm
beds on the island of Dago. Comparison of figures 8 and 9 will show

BARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 63

that the latter species has much larger zowcia, expanding more ab-
ruptly at the anterior end instead of increasing gradually in size.
C. inflata has shorter zocecia and a greater angle of divergence, while
C. abrupta has a still greater rate of expansion. The other Russian
species referred to the genus, C. dussemilis and C. schucherti, are much
coarser in every way.
Occurrence.—The original types were found in the Lower Cincin-
natian strata at Cincinnati, Ohio, but the species occurs abundantly
in nearly all the divisions of the Stones River and higher Ordovician
rocks of North America. It is also well represented in the Richmond
formation now assigned to the earliest Silurian. In Russia the known
occurrences are as follows: (1) A specimen with rather large zoccia,
incrusting a bifoliate bryozoan, in the Wassalem beds (D3) at Uxnorm,

Fig. 9.—CORYNOTRYPA BARBERI. @, PORTION OF THE TYPE-SPECIMEN, X9, INCRUSTING A BIFOLIATE
BRYOZOAN; b, SEVERAL ZO@CIA, X20. MIDDLE ORDOVICIAN, OTTOSEE FORMATION, KNOXVILLE, TEN-
NESSEE; c, PART OF A SMALL COLONY, X9, GROWING UPON A SPECIES OF HELIOLITES. EARLY SILURIAN,
LYCKHOLM FORMATION, HOHENHOLM, ISLAND OF DAGO, ESTHONIA.

near Reval (Cat. No. 57114, U.S.N.M.); (2) a typical example grow-

ing upon a fragment of Rhombopora esthoniz, from the Jewe lime-

stone (D1), Baron Toll’s estate, near Jewe (Cat. No. 57505, U.S.N.M.);
and (3) the impression of an example on the figured specimen of

Anolotichia sacculus from the Kuckers shale (C2) at the same locality

(Cat. No. 57506, U.S.N.M.).

The collections of the British Museum contain numerous specimens

of the species from American localities.

CORYNOTRYPA BARBERI Bassler.

Text fig. 9.

Corynotrypa barberi BasstER, Proc. U. 8. Nat. Mus., vol. 39, 1911, p. 509, text
fig. 8.

At first sight this species seems to be only an exceptionally large
form of Oorynotrypa delicatula, but upon closer inspection other dif-
ferences may be noted. These are, especially, the rapid swelling of

64 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

the zocecia after the stolonal portion has been left behind, and the
marked difference between the stolon and the zocecium proper. In
C. delicatula the angle of divergence is so small (15°), and the increase
in the zocecial diameter so gradual that it is difficult to discriminate
between the stolon and the zocecium proper. C. barberi, however,
with equally slender and long stolons, has an angle of 30°, which is
sufficient to cause the zocecium to stand out prominently. Compari-
sons of equally magnified views of this and related species indicate
the unusually large size of the zoccium in C. barberi, although its
stolon has practically the same dimensions as the more delicate forms.
The dimensions of the species are as follows: An average zocecium,
including the stolon, is 1 mm. long and 0.23 mm. wide at its greatest
diameter. The angle of divergence, as noted before, is 30°.

Occurrence.—Common in the Middle Ordovician (Ottosee) shales
in east Tennessee and southwest Virginia. Specimens indistinguish-
able from the types occur in the Lyckholm limestone (F1), incrust-
ing Halysites, at Hohenholm, island of Dago, Baltic Sea.

Holotype.—Cat. No. 57105, U.S.N.M.; Paratype, Cat. No. 57106,
U.S.N.M.

One specimen from the Lyckholm limestone, island of Dago, is in
the collections of the British Museum.

CORYNOTRYPA INFLATA (Hall).
Text fig. 10.

Alecto inflata Hatt, Nat. Hist. New York, Pal., vol. 1, 1847, p. 77, pl. 26, figs. 7a, 6.

Hippothoa inflata Nicuotson, Pal. Ohio, vol. 2, 1875, p. 268, pl. 25, figs. 1-10.

Stomatopora inflata Vine, Quart. Journ. Geol. Soc. London, vol. 37, 1881, p. 615.—
Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p. 176, fig. 3e; Geol.
and Nat. Hist. Surv. Minnesota, Final Rep., vol. 3, pt. 1, 1893, p. 117, pl. 1,
figs. 13-21; Zittel’s Textbook of Paleontology (Eng. ed.), 1900, p. 261, fig.
412B.—Simpson, Fourteenth Ann. Rep. State Geologist New York for the
year 1894, 1897, p. 597, figs. 202-204.—RurpremAnn, Bull. New York State
Mus., No. 49, 1901 [1902], p. 12, pl. 1, figs. 2, 3.—Cumines, Thirty-second
Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 886, pl. 32, figs. 1, la.

Corynotrypa inflata BassuER, Proc. U.S. Nat. Mus., vol. 39, 1911, p. 515, text figs.
ey ae) Tee

A single specimen from the Wesenberg limestone has characters
so typical of this abundant American form that I have no hesitancy
in identifying it as above. The essential characters of Corynotrypa
inflata are as follows:

Zoarium adnate, usually upon ramose or solid bryozoans or bra-
chiopods; zocecia typically short, pyriform, with the stolon but
slightly developed; eight or nine zoccia in 5 mm.; angle of diver-
gence averaging 40°. Exclusive of the stolon, a single zocecium is
0.4 mm. long and 0.26 mm. wide. The aperture has a distinct peri-

HARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 65

stome, is direct, circular, about 0.09 mm. in diameter, and situated
near the anterior end.

Occurrence.—The original types came from the Trenton rocks of
New York, where the zoarium is of more delicate growth than in the
higher formations; but specimens of C. inflata are generally abundant
in all of the Middle and Upper Ordovician and earliest Silurian (Rich-
mond) formations of North America. Typical examples have been

a

&

f @?P
S
3

Fig. 10.—CORYNOTRYPA INFLATA. d@ AND b, ZOARIUM, NATURAL SIZE, AND A PORTION, 9; Cc, THREE ZOG@CIA
OF SAME, X18, SHOWING THE POROUS WALL; d, A VERTICAL SECTION OF A ZO@CIUM, X18. LOWER PORTION
OF THE TRENTON FORMATION AT CANNON FALLS, MINNESOTA. @€ AND f/f, SMALL PORTION OF A COLONY,
INCRUSTING RAFINESQUINA ALTERNATA, X9 AND X18; g, OUTLINE OF ZOG@CIA, X18, SHOWING THREE
““GEMS” SPRINGING FROM ONE PARENT CELL. UPPER ORDOVICIAN (MAYSVILLE), CINCINNATI, OHIO.
(AFTER ULRICH.)

found in the Middle Ordovician (Wesenberg) limestone (EK), at Wesen-
berg, Esthonia, Russia (Cat. No. 57115, U.S.N.M.).
Numerous specimens from American localities are in the collections
of the British Museum. .
CORYNOTRYPA ABRUPTA Bassler.
Text figs. 11, 12.
Corynotrypa abrupta BassuER, Proc. U. 8. Nat. Mus., vol. 39, 1911, p. 517, text
figs. 16, 17.
Zoarium adnate, consisting of frequently branching, elongated, rather
large, clavate zocecia, much swollen at the anterior end. The tubular

66 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

proximal stolonal portion is almost threadlike, being not more than
0.04 mm. in width. This diameter is retained until the anterior

third or fourth is reached, when the zocecium abruptly swells, with .

an angle of divergence of 50°, and becomes rounded, with a diameter
of , 0.20). to, 0.25) mm.) vAm
average zoccium and its
stolon is 1.0 mm. long, but
in individual zoccia of the
same zoarlum the threadlike
proximal portion may range
in length from less than 0.10
mm.tolmm. The swollen
anterior zocecial portion,
however, is fairly constant in
: its measurements, as no devia-
Fig. 11—CORYNOTRYPA ABRUPTA. @ AND Db, PORTIONS OF : i LEN ie
THE TYPE-SPECIMEN, X9 AND X20, INCRUSTING A FRac- t1ON from a width ranging be-
MENT OF RHYNCHOTREMA CAPAY. RICHMOND GROUP, tween 0.20 mm. and 0.25 mm.
IRON RIDGE, WISCONSIN. :
and a length of 0.32 mm. to
0.40 mm. has been observed. The apertures are round, subterminal,
bordered by a slightly elevated rim, and small, averaging only about
0.09 mm. in diameter.

Corynotrypa abrupta is easily distinguished from all other species
of the genus by the narrow stolon and the very abrupt swelling of the
zocecium proper. In related species such as C. inflata (Hall) and C.
delicatula (James), the angle of divergence is less, giving a different
shape to the zoeciumasawhole. The
extreme variation in the length of
the narrow proximal portion is noted
above, and is indicative of the fact
that this part of the zocecium is the
least stable in simple _ species of
Cyclostomata.

Occurrence-—The American speci-
men illustrated in figure 11, upon
which the species is based, incrusts a
fragment of Rhynchotrema capax and
was found in the highest beds of the. ¥ie.12—CorynorryPa ABRUPTA. a AND b,

Maguoketa shale of the, Richmond, |/208?08/0" 4\esnuu O22) as
CRUSTING A CRINOID COLUMN. EARLY

group, at Tron Ridge, Wisconsin. The SILURIAN, LYCKHOLM FORMATION, KERTEL, ~

5 . v D ESTHONIA.
Russian examples assigned to the ““**? °* °*° ?

species were found associated with Calapacia cribriformis Nicholson,
Halysites sp., Streptelasma, and other fossils of the coral bed, in the
Lyckholm limestone (F1), at Kertel, island of Dago.

Holotype.—Cat. No. 54173, U.S.N.M.; Paratype, Cat. No. 57109,
U.S.N.M.

er ee

——

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 67

CORYNOTRYPA SCHUCHERTI Bassler.
Plate 6, fig. 1; text fig. 13.

Corynotrypa schuchertti BassteR, Proc. U. 8. Nat. Mus., vol. 39, 1911, p. 525,
text fig. 26.

Zoarium branching frequently, uniserial, incrusting, in the case of
the type-specimen, an example of Streptelasma. Zocecium com-
paratively large, averaging 1 mm. in length, irregularly club-shaped,
the anterior half swollen, with a maximum diameter of 0.40 mm.,
tapering gradually in the posterior half to the narrowest part with a
width of 0.15 mm., where it joins the distal end of the preceding one.

Fig. 13.—CoRYNOTRYPA SCHUCHERTI. @ AND b, PORTIONS OF THE TYPE-SPECIMEN, INCRUSTING A STREP-
TELASMA, X9; c, SEVERAL ZOG@CIA OF THE SAME, X20. WESENBERG LIMESTONE (EE), WESENBERG,
ESTHONIA.

Apertures subterminal, surrounded by a slight border, and with a
diameter slightly more than one-third that of the zocecium.

This species, which is named in honor of Prof. Charles Schuchert,
who collected the type-specimen, is related most closely to the com-
mon American form C. inflata, but differs conspicuously, however,
in having larger, less regular, more elongate and less rapidly expand-
ing zocecia. In general, C. schucherti is intermediate in its character
between C. inflata and C. dissimilis.

Occurrence.—Rare in the Wesenberg limestone (KE) at Wesenberg,
Esthonia.

Holotype-—Cat. No. 57111, U.S.N.M.

British Museum collections, one specimen.

68 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

CORYNOTRYPA DISSIMILIS (Vine).
Text fig. 14.

Stomatopora dissimilis VINE, Quart. Journ. Geol. Soc. London, vol. 37, 1881, pp.
615, 616, figs. 1-8; vol. 38, 1882, p.50.—BasstER, Bull. 292, U.S. Geol. Surv.,
1906, p. 15, pl. 4, figs. 15-19.

Stomatopora recta RINGUEBERG, Bull. Buffalo Soc. Nat. Hist., vol. 5, 1886, p. 20,
pl. 2, figs. 15, 15a.

Stomatopora minor Hennia, Arkiv fur. Zool., Kong. Sven. Vet.-Akad. Stockholm,
vol. 3, No. 10, 1906, p. 24, pl. 3, fig. 6. ,

Aulopora, species, Hatt, Nat. Hist. New York, Pal., vol. 2, 1852, pl. 50, figs.
27, 29.

Corynotrypa dissimilis BASSLER, Proc. U. 8. Nat. Mus., vol. 39, 1911, p. 523, text
fig. 23.

The identification of this species in Russian strata is based on speci-
mens from the Lyckholm limestone differing in no appreciable manner

Fig. 14.—CoRYNOTRYPA DISSIMILIS. @ AND b, A TYPICAL EXAMPLE OF THE SPECIES, X9 AND X20, INCRUSTING
THE EPITHECA OF THE BRYOZOAN DIPLOTRYPA NUMMIFORMIS. SILURIAN, ROCHESTER SHALE, LOCKPORT,
NEw YORK; ¢ AND d, POORLY PRESERVED SPECIMEN OF THE SPECIES, X9 AND X20, GROWING UPON
A SPECIMEN OF HELIOLITES. EARLY SILURIAN, LYCKHOLM FORMATION, KERTEL, ISLAND OF DAGo
ESTHONIA.

from the common Middle Silurian Corynotrypa dissimilis. The zoa-

rium is parasitic, consisting of uniserial branching zocecia, subcylin-

drical or club-shaped, 0.15 to 0.20 mm. in diameter at the proximal
end and increasing slowly to twice this width at the widest portion
of the distal end. Average zocecia are 1.15 mm. in length, with

5 to 6in 5 mm.; the apertures are subterminal, bounded by a shghtly

developed, rim-like border and so large that they occupy more than

three-fourths of the zocecial diameter. The typical form of the spe-
cies, however, is well marked transversely by fine wrinkles or stria-
tions. In the Russian specimens these striations are absent entirely,
the surface being smooth and minutely porous as in other species
of the genus. Aside from the absence of transverse striations, the
zocecia in these specimens show a tendency to be slightly larger and

———————_——————

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 69

relatively more expanded at their anterior end, differences which
the study of more material will probably remove, and which are
insufficient for the recognition of even a variety.

Occurrence.—The earliest appearance of C. disstmilis is in the Lyck-
holm limestone (F1), at Kertel, island of Dago (Cat. No. 57112,
U.S.N.M.). It has also been found in the Borkholm limestone (F2)
at Borkholm, Esthonia (Cat. No. 57113, U.S.N.M.). The types of the
species are from the Buildwas beds of the Wenlock shales, Shropshire,
England. The species occurs also in the Silurian beds, island of Goth-
land, where it has been given the name Stomatopora minor by Hennig.
It is abundant in the Rochester shales at Lockport and other locali-
ties in western New York, and at Grimsby, Ontario, and in the Os-
good beds at Osgood, Indiana.

Family ENTALOPHORIDA Reuss.

The Entalophorids comprise ramose Cyclostomata with the circu-
lar apertures exsert and opening on all sides. The single genus
discussed in the present paper was instituted for American Paleozoic
forms and has been placed by some writers as a synonym of the recent
genus Spiropora Lamouroux, but the latter, according to Ulrich, has
a definite central axis from which the zoccia originate, while, in
species of JMitoclema, this axis is absent and the tubes have their
origin in the manner of ordinary ramose forms. These two genera,
although probably closely related, exhibit the same differences dis-
tinguishing genera in other families.

Genus MITOCLEMA Ulrich.

Mitoclema Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 150; Geol.

Surv. Illinois, vol. 8, 1890, pp. 336, 369; Geol. Nat. Hist. Surv. Minnesota, vol.

3, pt. 1, 1893, p. 122.—Smrson, Fourteenth Ann. Rep. State Geologist New

York for the year 1894, 1897, p. 598.—NickLEs and Basser, Bull. 173, U.S.

Geol. Surv., 1900, p. 22.—BassteEr, Bull. 292, U. S. Geol. Surv., 1906, p. 18.

Zoarium ramose, cylindrical, consisting of long tubular zoccia,

which are thin-walled and prismatic in the axial region, diverge

gradually from the center, and bend abruptly outward near the

surface, often becoming free and much exserted; apertures terminal,
circular, usually arranged in regular transverse or subspiral series.

Genotype.— Mitoclema cinctosum Ulrich. Middle Ordovician of

Kentucky and Tennessee.

MITOCLEMA BOREALE, new species.
Plate 6, fig. 8; text fig. 15.

Zoarium of small, ramose, cylindrical, frequently bifurcating
branches, averaging 0.8 mm. in diameter. Interzoecial surface
smooth, minutely but clearly porous. Zocecia tubular, with rounded
apertures, 0.15 mm. in diameter, projecting only slightly above the
general surface of the branch, and arranged in ascending spiral rows.

70 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Measuring along one of these rows, four zocecia may be counted in a
distance of 2 mm.
Mitoclema boreale is distinguished from all other species of the genus
by the slight projection of the apertures above the zoecial surface.
Externally the species has a great resemblance
to Diploclema trentonense Ulrich,! with which I
had at first identified it, but thin sections
showed it to be distinct. A section across the
end of a branch, failed to reveal the bifoliate
features characteristic of Dzploclema, but
showed instead that the zoccia proceeded
from the center of the branches as in the type-
Fig. 15.—MITOCLEMA BOREALE. species of Mitoclema.
Fracment or a zoartum, Occurrence-——Abundant in the Wesenberg
X9. WESENBERGLIMESTONE limestone (HK) at Wesenberg, Esthonia, where
(E), WESENBERG, ESTHONIA. 3 :
the figured specimens were obtained. Less
common in the Orthoceras limestone (B3) at Port Kunda (Cat. No.
57186, U.S.N.M.) and in the Wassalem beds (D3) at Uxnorm,
Esthonia (Cat. No. 57185, U.S.N.M.).
Cotypes.—Cat. No. 57184, U.S.N.M.
One specimen from Wesenberg is in the British Museum collections.

MITOCLEMA ? MUNDULUM Ulrich.
Text fig. 16.

Mitoclema ? mundulum Uxricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890,
p. 177, figs. 4 a-c; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
1238, pl. 2, figs. 4-6

Fig. 16.—MITOCLEMA? MUNDULUM. @AND b, FRAGMENTS, NATURAL SIZE, AND X9; C, ORIGINAL OF Db, X18,
SHOWING SURFACE CHARACTER. NEMATOPORA BED OF TRENTON, CANNON FALLS, MINNESOTA. (AFTER
ULRICH.) d, PORTION OF YOUNG EXAMPLE, X9. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, NEAR
JEWE, ESTHONIA.

A single specimen from the Kuckers shale, Baron Toll’s estate, has
all the characters of young specimens of Mitoclema? mundulum

1 Geol. Surv. Illinois, vol. 8, 1890, p. 369, pl. 53, figs. 9-9c.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. Gy

described by Ulrich from the Lower Trenton shales of Minnesota.
Ulrich’s description is as follows:

Zoarium ramose, very small, the branches cylindrical, 0.5 or 0.6 mm. in diameter,
with faint transverse striee or wrinkles over the spaces between the zocecial apertures.
The latter are drawn out tube-like, about 0.15 mm. in diameter, and project strongly
upward and outward from the surface of the small stems. Their arrangement is in
rapidly ascending spiral series, with four or five in 2mm. As near as can be deter-
mined from the material at hand, the zocecial tubes diverge equally to all sides of the
branches from an imaginary axis.

Occurrence.—Common in the Nematopora bed of the Trenton, at
Cannon Falls, Minnesota. Apparently rare in the Kuckers shale
(C2), Baron Toll’s estate, near Jewe, Esthonia.

Plesiotype.—Cat. No. 57187, U.S.N.M.

Family IDMONEID Busk.

This family is represented in the Ordovician and early Silurian
rocks by the single genus, Protocrisina, which is possibly incorrectly
placed here. Typical Idmoneide are most abundant in the late
Cretaceous and Cenozoic times.

Genus PROTOCRISINA Ulrich.

Protocrisina Uuricu, Geol. Surv. Illinois, vol. 8, 1890, p. 369.—Pocta, Syst. Sil.
Centre Boheme, vol. 8, pt. 1, 1894, p. 16.—Uxricu, Zittel’s Textbook of Paleon-
tology (Eng. ed.), 1896, p. 262, text fig. 417.—NicKLEs and Basser, Bull.
173, U. 8. Geol. Surv., 1900, p. 21.

Protocrisina is a somewhat unusual genus distinguished from all
other genera of similar growth by the occurrence of small pores on
both sides of the branches. The generic characters are as follows:

Zoarium consisting of narrow, bifurcating branches, celluliferous
on one face only; zocwcia subtubular, with prominent, circular aper-
tures arranged in intersecting diagonal series; on both faces small pores
uregularly distributed.

Genotype—Protocrisina exigua Ulrich. Earliest Silurian (Rich-
mond) of the United States, Canada, and Sweden.

Only a single species has hitherto been recognized in this genus, but
the collections of the United States National Museum now contain
representatives of at least five distinct forms. The genotype was
described from specimens obtained in the Richmond group, but the
same species or a closely related variety was recognized in the early
Trenton strata of New York and Canada. The latter form was
described by Hall as Gorgonia? perantiqua,: but his description and
figures were, like many others of that early period, hardly sufficient
for the certain identification of the species. Hall’s type-specimen,

1 Nat. Hist. New York, Pal., vol. 1, 1847, p. 76, pl. 26, figs. 5a, b.

a2: BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

in the collection of the American Museum of Natural History, proves
to belong to a valid species of Protocrisina, differing from the genotype
in its more luxuriant growth of rigid, closely placed, remotely bifur-
cating branches spread upon a plane. The zocecial structure is very
similar in the two species and, although the close relationship of
Protocrisina exigua Ulrich and P. perantiqua (Hall) is recognized, it is
believed that the difference in growth is sufficient for specific recog-

Fig. 17.—PROTOCRISINA EXIGUA. @ TO €. WIMAN’S VIEWS OF CRISINELLA GILENSIS. @, FRAGMENT,
NATURAL SIZE; 0, CELLULIFEROUS SURFACE, X10, SHOWING THE CIRCULAR ZOG@CIA AND ACCESSORY PORES;
Cc, NONCELLULIFEROUS FACE, X10; d AND ێ, TWO TRANSVERSE SECTIONS, X10. BORKHOLM DRIFT, OLE
MyRk, ISLAND OF GOTHLAND. f TO 7, ULRICH’S VIEWS OF PROTOCRISINA EXIGUA. {, TWO FRAGMENTS,
NATURAL SIZE; g, CELLULIFEROUS FACE, X18, WITH ZO@CIAL OPENINGS AND ACCESSORY PORES; h, NON-
CELLULIFEROUS SIDE, X18, WITH PORES; i, TRANSVERSE SECTION, X18. FERNVALE LIMESTONE OF RICH-
MOND GROUP, WILMINGTON, ILLINOIS.

nition. This same close relationship between Black River or early
Trenton and Richmond species has been noted in a number of
instances. Three well-marked new species are known. The first is
described in the present work as Protocrisina ulrichi, while the sec-
ond and third, which await description, are not uncommon in the
Nematopora bed of the Trenton in Minnesota, and in the Middle
Ordovician (Ottosee) shales of eastern Tennessee, respectively.

|
|
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HARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 73

PROTOCRISINA EXIGUA Ulrich.
Text fig. 17.

Protocrisina exigua Uuricu, Geol. Surv. Illinois, vol. 8, 1890, p. 405, pl. 29, figs.
4-4e; pl. 53, figs. 11-lle; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p.
262, text fig. 417 —Cumines, Amer. Journ. Sci., ser. 4, vol. 20, 1905, pl. 7,
fig. 53.

Crisinella wilensis Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, 1902, p.
181, pl. 6, figs. 12-16.

In the small bryozean fauna described by Wiman from drift bowl-
ders of the Borkholm formation is a species, Crisinella wilensis so
similar to the American Protocrisina exigua that I am forced, even in
the absence of specimens, to consider them synonymous. The
figures of both Ulrich’s and Wiman’s species are reproduced here,
and show at a glance their practical identity. Indeed, the only dif-
ference to be observed is that Wiman has omitted the small pores on
his figure of the nonecelluliferous side, although he shows them dis-
tinctly on the other face. These pores are so easily overlooked that
their omission is probably due to faulty observation rather than to
real absence.

The original description of Protocrisina exigua is as follows:

Zoarium ramose; branches slender 0.6 mm. wide, 0.3 to 0.45 mm. thick, dividing
dichotomously at a very acute angle at intervals varying from 2 to 7 mm. Cel-
luliferous side strongly convex, smooth, with four, occasionally only three, series
of zocecia. Reverse faintly convex, flattened or slightly concave in the central part,
finely striate, the striz often minutely granulose. Zocecia subtubular, thin-walled
within, with prominent tubular mouths. Apertures subcircular, 0.09 mm. in diameter,
5 or 54 in 2 mm. vertically; arranged in oblique rows. A small number of circular
pores, 0.04 mm. in diameter, are scattered over both the reverse and celluliferous faces.

Occurrence—Common in the Fernvale shales of the Richmond
group in Illinois and other States where these strata outcrop. The
Kuropean examples were obtained from drift bowlders of the Bork-
holm limestone (F2) at Ojle Myr, island of Gothland.

Specimens from American localities are in the collections of the
United States National Museum and the British Museum.

PROTOCRISINA ULRICHI, new species.
Plate 12; text fig. 18.

Zoarium of ramose, slender branches, averaging 0.4 mm. in width,
dividing dichotomously at rather regular intervals of about 4 mm.
and at an angle averaging 35°. Celluliferous side slightly convex,
with two rows of quite regularly arranged zoccia, noncelluliferous
side smooth and flattened with a distinct sulcus along its mid-length.
Zocecial apertures oval, 0.15 mm. in their longer diameter, arranged
alternately in distinct diagonal and also longitudinal rows; measur-
ing longitudinally, 5 to 6 zocecia in 2 mm. The accessory pores are
extremely small, circular to elongate, and are abundant on both sides

74 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

of the zoarium. On the celluliferous face they are almost entirely
restricted to the middle length and occur in a unilinear series. The
same restriction to the mid-length is present on the noncelluliferous
face, where, however, the pores open at the bottom of a suleus
extending the full length of the
branch. Occasionally a few of
the same pores are found outside
of this middle line.
The above description ap-
plies to the normal or average
branches. Old examples show
greatly thickened stems with the
regular arrangement of the
zocecial apertures and accessory
pores quite indistinct. When
0 compared with other members
Ne of the genus, the common occur-
Fic. 18.—PROTOCRISINA ULRICHI. @, PORTION OF A yence of the pores along a middle

ZOARIUM, NATURAL SIZE; b, ANOTHER FRAGMENT, : x uae :
SHOWING THE NONCELLULIFEROUS SIDE, NATURAL line is the most distinctive char-

SIZE, AND ENLARGED EIGHT DIAMETERS. ee acter of P. ulricha, but other fea-
MEDIAN ROW OF PORES IS MOST CONSPICUOUS;

C, CELLULIFEROUS SIDE OF ANOTHER FRAGMENT, tures are the large size of the aper-
x 8, EXHIBITING THE REGULAR ARRANGEMENT OF t d tl ° a ]
THE ZOGCIA AND ACCESSORY PORES. KUCKERS ures an 1e1r regu ar arrange-
SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA. ment in two longitudinal rows.
Occurrence—Not uncommon in the Kuckers shale (C2), Baron
Toll’s estate, near Jewe, Esthonia.
Cotypes. Cat. No. 57188, U.S.N.M.

British Museum collection, three specimens.

Family CERAMOPORID Ulrich.

This very characteristic family of Bryozoa is well represented in
the Russian deposits by new or described species of all its genera save
two unusual types, Ceramophylla and Chiloporella, each of which is
known only from a single species. In America, specimens of cera-
moporoid bryozoans are often exceedingly abundant, but the collec-
tions from Russia have yielded comparatively few examples of the
rather numerous species determined. This, however, may be due
to a lack of systematic collecting rather than to actual scarcity of
material. The family is one of the most important of Paleozoic
bryozoans and is undoubtedly the progenitor of the equally important
Fistuliporide, so prolific in Silurian, Devonian, and Mississippian
rocks. The Ceramoporide are sparsely represented in the Silurian
and the family is essentially an Ordovician one.

Externally a ceramoporoid may be identified by its more or less
oblique aperture with a portion of its margin elevated into an over-
arching hood known as the lunarium. This elevated portion accen-
tuates the oblique aspect of the aperture and often gives an imbri-

;
)

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 75

eated appearance to the zoccia. The internal structure in the
family is equally characteristic, in fact, so much so that the term
“‘ceramoporoid structure” has its own definite meaning. Thin sec-
tions, magnified 20 or more times, show that the cell walls are
minutely porous and are composed of irregularly laminated and
intimately connected tissue. Microscopic examination is, however,
not necessary for a preliminary determination of a ceramoporoid
because the intimately connected tissue forming the cell walls, from
its very nature, will show no distinct fracture. If a trepostomatous
bryozoan be broken, the fracture will be clean-cut and clear, sepa-
rating adjoining cells, but in the case of a ceramoporoid, the break
will proceed through or across the walls indiscriminately, and present
a dull, structureless surface such as would be produced in an amor-
phous body. This style of fracture, however, is not limited to the
Ceramoporide but is present in the Fistuliporide and all the families
referred to the Cyclostomata. Undoubtedly this order of Bryozoa
must have had a different chemical composition from other orders
like the Trepostomata. The latter seem to contain more crystalline
calcite in their structure, while the Cyclostomata apparently have
more corneous material as a part of their skeleton. Certain genera,
Ceramopora especially, distinctly show large pores piercing the walls
and thus connecting adjoining zowcia and mesopores. Good ex-
amples of such connecting pores are illustrated on the following pages.
The zoccia in the different members of the family are sometimes in
contact but more frequently they are separated by more or less
irregularly shaped mesopores which are free from any connecting or
strengthening tissue. The Fistuliporide, on the other hand, may be
said to differ principally in having the inter-zocecial spaces occupied
by vesicular tissue. Such vesicular tissue, although poorly devel-
oped, is shown in the primitive fistuliporoids described on later pages
as Histulipora promeva and Chilotrypa immatura.

Various methods of growth obtain in the Ceramoporide, and in
some cases the shape of the zoarium constitutes a good generic char-
acter. Another genus, on the contrary, may include a variety of
forms of growth, in which case it must be distinguished by other
features such as the development and shape of the lunarium, the
occurrence of minute tubules traversing the lunarium lengthwise,
and the presence or absence of mesopores. These distinctive features
are cited under the discussion of the individual genera. The chief
characters of the family have been described by Nickles and Bassler
as follows:

Zoarium variable; maculz or clusters of mesopores or of zocecia larger than usual
at regular intervals; zocecia tubular, at first prostrate, continue obliquely or directly
to the surface, often with a few diaphragms; apertures commonly oblique, provided
with a lunarium; mesopores generally present, always irregular and usually without
diaphragms; walls minutely porous, formed of intimately connected and irregularly
laminated tissue.

92602°—Bull. 77—11——7

76 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Genus CERAMOPORA Hall.

Ceramopora Hatt, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 400; Nat. Hist.
New York, Pal., vol. 2, 1852, p. 168.—Picret, Traite de Pal., vol. 4, 1857,
p. 170.—Etcuwatp, Lethza Rossica, vol. 1, 1860, p. 412.—Zrrren, Hand-
buch d. Pal., 1880, p. 617.— VINE, Quart. Journ. Geol. Soc. London, vol. 36,
1880, p. 358.—Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p.
156.—Forrste, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 169.—H ah
and Simpson, Nat. Hist. New York, Pal., vol. 6, 1887, p. xviii.—JameEs and
James, Journ. Cincinnati Soc. Nat. Hist., vol. 11, 1888, p. 36.—MiuuErR,
North Amer. Geol. and Pal., 1889, p. 296.—Uzricu, Geol. Surv. Illinois,
vol. 8, 1890, pp. 380, 462.—Pocta, Syst. Sil. Centre Boheme, vol. 8, pt. 1,
1894, p. 112.—Utricu, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p.
267.—Simpson, Fourteenth Ann. Rep. State Geologist New York for the year
1894, 1897, p. 563.—NicKLEs and Bassxter, Bull. 173, U. S. Geol. Surv.,
1900, p. 23.—BassuER, Bull. 292, U. S. Geol. Surv., 1906, p. 18.—Hnnie,
Archiv. fur Zool., vol. 4, No. 21, 1908, p. 1.

This, the typical genus of the family, is sparsely represented in
American deposits, where, however, all the valid species so far
described occur in the Silurian. The discovery of several undoubted
forms in the Russian Ordovician is, however, only in line with what
would be expected of the geological distribution of the genus. A
number of genera were represented in the species originally assigned
to Ceramopora by Hall and others, but in 1890 Ulrich? restricted
the genus to the type species C. imbricata, making its discoidal growth,
peculiar spongy basal tissue in connection with the indefinite wall
structure, large mural openings, and absence of diaphragms, the
characteristic features. Since that time additional species have
been discovered so that at present growth in the genus may be free,
discoid, lamellate, massive, or incrusting, the basal spongy layer may
be absent and diaphragms may or may not occur. In addition to
the ceramoporoid structure, the diagnostic features of the genus are,
externally, the occurrence of large, irregular zoccia, comparatively
large and equally irregular open mesopores, prominent but often
poorly defined lunaria, and, internally, the presence of especially
large openings in the walls, allowing communication between the cells.
While this delimitation of the genus seems rather mdefinite when
compared with more sharply defined genera in the family, the very
irrecularity of the lunarium, zocecium, and mesopores, gives such an
unusual aspect to a zoarium that species may be determined with-
out much trouble. Indeed, the recognition of a species of Ceramopora
is a matter more readily performed by a study of actual specimens
than by its description.

Genotype—Ceramopora imbricata Hall. Niagaran of the United
States and Canada.

1 Geol. Surv. Illinois, vol. 8, pp. 380, 462.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 77

CERAMOPORA SPONGIOSA, new species.

Text fig. 19.

Zoarium a small, explanate mass several centimeters in diameter
and less than 5 mm. thick. Celluliferous surface smooth; noncellu-
liferous basal side lined with a strongly wrinkled epitheca. The
macule in young expansions are small, slightly depressed areas from
which the zoccia radiate; in old examples they are represented by
clusters of irregular, thick-walled mesopores. Zocecia large, 4 to 5 in 2
mm., irregularly polygonal in outline, with occasional mesopores.
Walls of both zocecia and mesopores irregular in shape and thickness.

Fig. 19.—CERAMOPORA SPONGIOSA. a, PORTION OF A ZOARIUM, NATURAL SIZE, SHOWING CONCENTRIC
RINGS OF EPITHECA; 6 AND Cc, TANGENTIAL SECTION, X9, AND PORTION OF SAME, X20, SHOWING THE
NUMEROUS CONNECTING PORES; d, TANGENTIAL SECTION OF THREE ZOG@CIA, X20, EXHIBITING STRUCTURE
OF WALLS AND OF THE LUNARIUM; € AND f, VERTICAL SECTIONS, X9 AND X20, WITH TABULATION AND
CONNECTING PORES. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

z

Lunarium of considerable size but so irregular in old specimens that
it can hardly be separated from the equally irregular zocecial wall.
In young exampies the relations of the zocecia, mesopores, and lunaria
are more clearly shown. Here the zocecium is more rounded and has
a distinct, slightly elevated, hood-shaped lunarium overarching the
proximal fourth of the zocecial cavity. Mesopores are represented in
such specimens by shallow pit-like depressions just behind the
lunarium.

While a considerable variation is shown at the surface of speci-
mens according to their age, the internal characters of the species

78 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

are more constant. The most obvious feature of thin sections is the
unusual number and size of the connecting pores, which give almost
a spongy aspect. The views seen in tangential sections are shown in
figure 19 b, c,d, where it may be noticed that the lunarium is not
clearly outlined from the rest of the zoccial wall. The mural pores
are perhaps shown more clearly in vertical sections, especially under
a high power of magnification, as in figure 19f. A few delicate
diaphragms placed irregularly are developed in the tubes.
Ceramopora spongiosa is the oldest known species of the genus

and differs from all other forms in its few mesopores, large, indistinct.

lunarium, and numerous connecting pores.

Occurrence.—Not uncommon in the Wassalem beds (D3) at
Uxnorm, near Reval, Esthonia.

Holotype.—Cat. No. 57189, U.S.N.M.

Thin sections of the type-specimen are in the collections of the
British Museum.

CERAMOPORA INVENUSTA, new species.

Plate 6, fig. 3; text fig. 20.

This bryozoan presents the most unusual surface characters of
any species known to me, indeed, the zocecial and mesopore walls
are so irregular and bear so many knob-like acanthopores or granules
that specimens show considerable resemblance to certain sponges or
to stromatoporoids. . This unusual appearance pertains only to the
mature portions of the zoarium, for young specimens have the usual
imbricated cells and lunaria of a ceramoporoid.

The zoarium is incrusting; the type-specimen, an expansion over
5 cm. long, is growing upon a large gastropod, while other examples
are incrusting ramose bryozoans. The zocecial surface is smooth,
with distinct macule of thick-walled mesopores distributed at inter-
valsof4to5mm. The zoccia are large, 3 to 4 in 2 mm., direct, and,
except in young stages, show little trace of a lunarium. The aper-
tures are irregularly rounded and are frequently indented by the
expanded zoccial walls. The latter are thick but the thickness varies
on account of the presence of numerous large, granular-like acantho-
pores. Whenever one of these structures is developed, the walls
expand to accommodate it, thus giving the irregular or indented effect
seen at the surface and in tangential sections. Such granules or
modified acanthopores are known in a number of ceramoporoids,
especially in certain species of Ceramoporella, but they are unusually
well developed in the present form. Mesopores are numerous and
sometimes isolate the zocecia completely.

Tangential sections bring out particularly the thick, irregular cell
walls and the numerous large granules or acanthopores. The luna-
rium, although scarcely distinguishable, is represented in such sec-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 719

tions by a slight thickening of the wall. The cell walls are unusually
contorted in the macular spaces, which, as shown in figure 20 a, are
composed almost entirely of mesopores. Vertical sections show the
usual short, immature region with thin walls bending gradually into
the thick walled mature zone. Diaphragms are absent in all of the
sections studied.

The incrusting zoarium, thick-walled, irregularly rounded zoccia

Fig. 20.—CERAMOPORA INVENUSTA. @, TANGENTIAL SECTION, X20, THROUGH A MACULA AND NEIGHBOR-
ING ZOGCIA; 6, TANGENTIAL SECTION, X20, SHOWING THE IRREGULAR ZOG@CIA AND NUMEROUS GRANULES
OR ACANTHOPORES; C, VERTICAL SECTION, X20, THROUGH A ZOARIUM EXHIBITING THE CHARACTERISTIC
COMMUNICATION PORES. WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

with large granular structures, indenting the aperture, gives an aspect
to the present form quite different from any other species of the genus.

Occurrence—Not uncommon in the Wesenberg limestone (E) at
Wesenberg, Hsthonia. ©

Holotype-—Cat. No. 57190, U.S.N.M.

A fragment of the type-specimen and thin sections are in the collec-
tions of the British Museum. ,

CERAMOPORA INTERCELLATA, new species.

Plate 6, fig. 2; text fig. 21.

Externally this new form has less resemblance to Ceramopora than
the two species just described; but thin sections bring out the char-
acteristic ceramoporoid structure, and especially numerous connect-
ing mural pores. The type-specimen is a flat, epithecated expansion,
consisting of two superposed layers of zocecia, as shown in figure 21 a.
The celluliferous face bears the apertures of large polygonal zocecia,
nearly always completely isolated by numerous irregularly polygonal
mesopores. The poriferous side is smooth, but exceptionally large

80 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

macule composed entirely of mesopores are present at intervals of
5mm. A portion of a macula with several zocecia and their interven-
ing mesopores is shown on plate 6, figure 2. A lunarium occupying
about one-fifth of the apertural wall is present, but it is little elevated
and is hardly distinguishable either at the surface or in thin sections.
An average zocecium is 0.40 mm. in diameter and three may be counted
in a distance of 2 mm.

The essential internal characters are believed to be shown in the
accompanying figures. After leaving the immature region, which,
as in other incrusting or lamellate ceramoporoids, is quite short, the
zocecial walls thicken and numerous connecting pores are developed.

mma LLIN
IME .

Fig. 21—CERAMOPORAINTERCELLATA. @, EDGE VIEW OF THE FRAGMENTARY TYPE, X1; 0 AND c, TANGEN-
TIAL SECTION, X20, AND A PORTION, X35, EXHIBITING THE INDISTINCT LUNARIUM AND CONNECTING PORES;
d, VERTICAL SECTION, X20, THROUGH ONE LAYER OF THE ZOARIUM. LYCKHOLM LIMESTONE (F1),
HOHENHOLM, ISLAND OF DAGO, ESTHONIA.

A few thin diaphragms are inserted in both the zoccial tubes and the
mesopores. The connecting pores are equally conspicuous in the
tangential section, where also the lunarium may be detected as a °
slight thickening of the posterior portion of the zocecial wall.

The lamellate growth, large, angular zocecia, isolated by numerous
mesopores, and the large macule, are characters so different from
other species of Ceramopora that comparison is unnecessary.

Occurrence.—Apparently rare in the Lyckholm limestone (F1) at
Hohenholm, island of Dago.

Holotype-—Cat. No. 57191, U.S.N.M.

A thin section of the type-specimen is in the collections of the
British Museum.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 81

Genus CERAMOPORELLA Ulrich.

Ceramoporella Uuricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 156.—
Miter, North Amer. Geol. and Pal., 1889, p. 297.—Uuricu, Geol. Surv.
Illinois, vol. 8, 1890, pp. 380, 464; Geol. and Nat. Hist. Surv. Minnesota, vol,
3, pt. 1, 1898, p. 328.—Pocra. Syst. Sil. Centre Boheme, vol. 8, pt. 1, 1894.
p. 15.—Utricu, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p.
267.—Simpson, Fourteenth Ann. Rep. State Geologist New York for the
year 1894, 1897, p. 564._NickiEs and Bassier, Bull. 173, U.S. Geol. Surv.,
1900, p. 23.—BassteR, Bull. 292, U.S. Geol. Surv., 1906, p. 20.—Cumines,
Thirty-second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 742.

Zoarium of incrusting layers, which by superposition may form
masses; zocecia short, tubular with thin walls; apertures oval, ob-
lique, the lunarium forming a hood; mesopores abundant, often com-
pletely encircling the zocecia.

Genotype.—Ceramoporella distincta Ulrich. Upper Ordovician
(Eden and Maysville) of the Ohio Valley.

Until recently this genus has included all of the parasitic Ordovi-
cian ceramoporoids, but the discovery of the foregoing Russian
species of incrusting, although otherwise typical Ceramopora in Ordo-
vician strata, causes this conception to be modified. Ceramoporella
includes two well-marked sections or groups of species, one in which
the zocecia are inclined to be rhomboidal or polygonal in outline and
more or less in contact, and another with rounded or ovate apertures
and numerous mesopores. One or more distinct species of each sec-
tion usually occur in each of the Ordovician formations, while a few
species are of such generalized types of structure that they range
through several formations and can be distinguished at best only as
varieties. The new variety following belongs to the latter category.

CERAMOPORELLA GRANULOSA MINOR, new variety.
Text fig. 22.

In 1890 Ulrich described a new species of Ceramoporella from the
Fernvale shale division of the Richmond group, at Wilmington, IIli-
nois, naming it C. granulosa * because of the numerous, acanthopore-
like granules occurring in the walls. Further study has shown that
this same species, variously modified, occurs in most of the Ordovi-
cian formations commencing with the Black River. Only one of
these varieties has received a name, but all of them differ from the
type form in minor details only. Thus, the present form differs only
in having slightly smaller zocecia and fewer granules.

In the species itself as well as in the varieties, the zoarium is in-
crusting a foreign body and by the superposition of several layers
forms masses of some size. The zoarial surface is smooth and granu-
lose, with the usual macule. Zocecial apertures oval, opening at the

1 Geol. Surv. Illinois, vol. 8, p. 466, pl. 41, figs. 2, 2¢.

82 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

surface directly, from 0.2 to 0.3 mm. in diameter, about 6 in 2 mm.

Numerous small mesopores are present among the zocecia and usually
isolate them. Lunarium narrow but prominent, occupying one-
fourth to one-third of the wall’s circumference. Thin sections show
the usual laminated wall tissue of the Ceramoporide. The granules
or acanthopore-like structures are most pronounced in tangential
sections.

Fic. 22. CERAMOPORELLA GRANULOSA MINOR. @, TANGENTIAL SECTION, X20, SHOWING FEW GRANULES
AND GENERAL ARRANGEMENT OF ZOG@CIA AND MESOPORES; b, VERTICAL SECTION, X20, THROUGH A SINGLE
LAYER OF ZOG@CIA. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

Occurrence.—The new variety minor is described from specimens
occurring in the Jewe limestone (D1), Baron Toll’s estate, near Jewe.
Tt is also known from the Wassalem beds (D3) at Uxnorm, Esthonia,
and from the Black River (Decorah) shales of Minnesota.

HolotypeCat. No. 57192, U.S.N.M.

The collections of the British Museum contain a specimen from the
Jewe limestone, Baron Toll’s estate.

_ CERAMOPORELLA UXNORMENSIS, new species.

Text fig. 23.

Zoarium incrusting, forming expansions several millimeters thick
and as many centimeters in width. Surface smooth but with clusters
of larger zocecia from which the ordinary ones radiate. Zocecia with
moderately thick walls; apertures subrhomboidal to irregularly polyg-
onal, oblique on account of the small but distinct overarching
lunarium. Zocecia arranged in rather regular radiating series about
the maculz; five zoccia in 2mm. Mesopores few, often entirely
absent.

The most conspicuous feature of thin sections is the unusual thick-
ness and distinctness of the lunarium, characters which are not so well
shown at the surface. In vertical sections the zocecial tubes are
prostrate and thin-walled in the axial region, but thicken and show the
characteristic laminated wall structure in the peripheral zone. Both
regions are without diaphragms.

Although closely allied to several American Ordovician species,
such as Ceramoporella ohioensis (Nicholson) and C. whitei (James), the

BARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 83

present form may be distinguished by its unusually thick and dis-
tinct lunarium. The type-specimen is in such condition that the
surface could not be figured, but by slight etching, such a view as
shown in figure 23a is obtained.

Fig. 23._CERAMOPORELLA UXNORMENSIS. @ AND b, TANGENTIAL SECTION, X20 AND X35, ILLUSTRATING
THE SHAPE OF ZOG@CIA AND THE THICK LUNARIUM; C, VERTICAL SECTION, X20. WASSALEM BEDS (D3),
UxXNORM, ESTHONIA.

Occurrence.—Apparently rare in the Wassalem beds (D3) at
Uxnorm, Esthonia.

Holotype.—Cat. No. 57194, U.S.N.M.

Thin sections of the type-specimen are in the collections of the
British Museum.

Genus CQ2®LOCLEMA Ulrich.

Celoclema Uxricn, Journ. Cincinnati Soc. Nat Hist., vol. 5, 1882, p. 137; vol. 7,
1884, p. 49.—NicKLEs and Basser, Bull. 173, U.S. Geol. Surv., 1900, pp. 24,
211.—BassLER, Bull. 292, U. 8. Geol. Surv., 1906, p. 21.—Cumines, Thirty-
second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 742.

Diamesopora (part) Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 380, 467; Geol.
Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 330.

Diamesopora Uuricu, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 268.

Zocecia very much as in Ceramoporella but differing in forming a
zoarium of ramose, hollow branches lined internally with a striated
epitheca.

Genotype.—Diamesopora vaupelt Ulrich. Upper Ordovician (Eden)
of the Ohio Valley.

This genus is readily distinguished from related members of the
Ceramoporide by its zoarial characters. Five species have been
described from the American Ordovician and Silurian deposits, while
at least three new forms await description. The following new
species is closely related to one of the undescribed American Middle
Ordovician forms, but differs from this as well as all other species of
the genus in its larger zocecia and unusually thick walls.

84 BULLETIN 77, UNITED STATES NATIONAL MUSEUM. ’

C@LOCLEMA CRASSIMURALE, new species.
Plate 7, fig. 12; text fig. 24.

This new species is founded upon a single fairly well preserved
specimen 18 mm. long and 5 mm. in diameter. The zoccial layer
averages a millimeter in thickness, while the axial tube, now filled
with clay, varies from 1 to 1.5 mm. in diameter. The zoccial
apertures are rather large, 4 in 2 mm. measuring along their greater
leneth, and are irregularly oval in shape. Macule are present at
regular intervals, and form depressed spaces from which the zocecia
radiate somewhat irregularly. Mesopores are numerous, small, and
very irregular in shape and position. Both zocecia and mesopores

Fig. 24.—C@LOCLEMA CRASSIMURALE. @, FRAGMENT OF A ZOARIUM, NATURAL SIZE, WITH END VIEW OF
THE SAME SHOWING THE CENTRAL TUBE; b, TANGENTIAL SECTION, X20, EXHIBITING THE THICKNESS OF
WALLS, OBSCURE LUNARIUM, AND SMALL, IRREGULAR MESOPORES; C, VERTICAL SECTION, X20, THROUGH
ONE SIDE OF A ZOARIUM. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

have unusually thick walls. The lunarium is inconspicuous both at
the surface and in thin sections.

Although closely related to the typical forms of the genus, C. crassi-
murale proves upon comparison to have larger zocecia and thicker
walls than any described form. None of the associated bryozoans
has a central tube, and this fact alone will aid in its determination.

Occurrence.—Rare in the Jewe limestone (D1), Baron Toll’s estate.
Specimens which are believed to represent the parasitic base of this
species have been found in the Jewe limestone associated with the
type-specimen, and also in the Wassalem beds (D3), at Uxnorm. At
the latter locality no specimens of the erect, hollow stems have been
noted.

Holotype.—Cat. No. 57195, U.S.N.M.

British Museum’s collections, thin section of the type-specimen.

————————————

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 85

CG@LOCLEMA LACINIATUS (Eichwald).
Text fig. 25.

Cenites laciniatus Excowaip, Lethzea Rossica, vol. 1, 1860, p. 459, pl. 27, fig. 9.

EKichwald has given two figures, here reproduced, of a ceramopo-
roid bryozoan from the ‘‘calcaire & schiste argileux inflammable,”
which I have little hesitancy in identifying as a species of Celoclema
occurring in the Kuckers shale. His description cites the type-speci-
men as an incrusting lamella with the surface irregularly undulating.
The specimens before me agree exactly with
Kichwald’s figure of the zocecia, and, more-
over, appear to be incrusting, undulating
lamelle, but careful examination showed
that they represent in reality the flattened
‘sides of a hollow, tubular, ramose zoarium.
Such zoaria spread out at their base into an
incrusting expansion, and it is possible there-
fore that Eichwald’s type represents the base __

: Fig. 25—C@LocLEMA LACINIA-
instead of the flattened branch. Atanyrate, ows. a, E1cHwat’s tyPE-
I believe that the recognition of Cenites ‘FBCMEN, NATURAL sux, oF

read : at COENITES LACINIATUS; b, SUR-
laciniatus as a species of Celoclemaisin keep- rack or tHe same, ENLARGED.
ine with the facts. KUCKERS SHALE (C2), EsTHo-

5 5 NIA. (AFTER EICHWALD.)

Theinternal structure, although poorly pre-
served in the specimens studied, agrees in all respects with that of
typical Celoclema. The zocecial apertures as shown in Eichwald’s
enlargement of the surface, are arranged in diagonal rows with a dis-
tinct, although little arched, lunarium. Measuring along one of these
rows, four zocecia occur in 2mm. The hollow zoarium of this species,
when uncrushed, is about 5 mm. in diameter; the zoecial layer itself
is less than 0.5 mm. thick.

Occurrence.—Apparently rare in the Kuckers shale (C2) at Erras
and Reval, Esthonia. (Cat. No. 57197, U.S.N.M.)

Genus CREPIPORA Ulrich.

Crepipora Utrics, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 157.—MILLER,
North Amer. Geology and Paleontology, 1889, p. 299.—Uricu, Geol. Surv.
Illinois, vol. 8, 1890, pp. 380, 469; Geol. and Nat. Hist. Surv. Minnesota, vol.
3, pt. 1, 1893, p. 322.—Pocra, Syst. Sil. Centre Boheme, vol. 8, pt. 1, 1894,
p. 15.—Utrica, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 268.—
Stupeson, Fourteenth Ann. Rep. State Geologist New York for the year 1894,
1897, p. 566.—Nickizs and Bassier, Bull. 173, U. S. Geol. Surv., 1900,
p. 23.—Hennie, Archiv fur Zool., vol. 4, No. 21, 1908, p. 9.

Zoarium incrusting lamellate or massive, or in one species form-
ing hollow branches; zocecia long, tubular, thin-walled, with dia-
phragms; apertures angular or subpyriform, lunarium not over-
arching, its ends.usually projecting; mesopores generally restricted
to the macule, which are elevated or depressed.

86 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Genotype.—Crepipora simulans Ulrich. Upper Ordovician (Mays-
ville) of the Ohio Valley.

Crepipora is closely related to the genus Ceramoporella, incrusting
forms of the former being very similar to such species as Ceramoporella
_ uxnormensis described on page 82. Perhaps the most obvious generic
difference is the practically complete restriction of the mesopores to
the macule in Crepipora, although other equally good characteristics
are the more direct zoccial apertures, the better developed macule,
and the greater distinctness of the lunarium.

The zoarial growth in Creprpora varies from thin, incrusting sheets
to solid massive or hemispherical, and in one case regular hollow
branches. The surface shows thin-walled, erect, rhomboidal to polyg-

onal zocecia, each having a small but distinct lunarium on the proxi- —

mal edge. Macule of mesopores developed at regular intervals are a
feature of the surface, where they appear as minutely porous elevations
or depressions. In thin sections the macule and lunaria are most
evident, although the ceramoporoid structure described under the
discussion of the family is likewise conspicuous.

At least 15 new or described American species of Crepipora are
known, and these, in addition to the three new forms here defined,
make the genus one of the more prolific members of the Ceramoporide.
The three Russian forms have little relationship with each other
specifically, but are good examples of the range of structure in the
genus. The first, C. schmidti, is closely related to the genotype
C. simulans, from the middle Cincinnatian strata of the United
States, differing particularly in having considerably larger zoccia.
The second species is unusual in the irregular angularity of its zocecia,
its very distinct crescentic lunarium, and the unusual development
of mesopores. C. incrassata has particularly thick walls, but a quite
unusual character seen only in this species, so far as known, is the
rounded, ovicell-like structure noted in the thin sections of the type-
specimen.

The occurrence of these cystlike bodies in an undoubted species of
Crepipora is of great interest in its bearing upon the zoological posi-
tion of the ceramoporoids and related monticuliporoids. ‘These two
groups, together with the fistuliporoids, have been assigned to the
alcyonarian corals by most writers, but with the present discovery in
Crepipora, ovicell-like structures are now known to occur in repre-
sentatives of each group. This fact, together with others indicating
the bryozoan relations of these disputed organisms, will be discussed
in another paper at a later date.

een OE ee

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 87

CREPIPORA SCHMIDTI, new species.
Text fig. 26.

Cir. Crepipora simulans Utricu, Geol. Surv. Illinois, vol. 8, 1890, p. 470, pl. 39,
figs. 4, 4a; pl. 40, figs. 3, 3a; text fig. 8b, p. 320.

This species is represented in the collections by only the type-
specimen, which is a small, well-developed zoarium incrusting a
gastropod. Although samintle | in this respect, the greatest thickness
of this zoarium does not exceed 2mm. Other specimens undoubtedly
will show a greater thickness of the individual crust or will be made
up of a number of crusts growing successively upon each other. The
maculz are indistinctly marked in the specimen at hand, but, as in
similar incrusting species, they are composed of clusters of mesopores
surrounded by slightly larger zocecia. Zocecial apertures compara-
tively large, direct, rhomboidal to subpolygonal in shape, averaging
0.4 mm. in their greater diameter; walls of zocecia thin. Four to

Fig. 26.—CREPIPORA SCHMIDTI. @, VERTICAL SECTION, X20, SHOWING LAMINATED WALL STRUCTURE; ),
TANGENTIAL SECTION, 20, WITH SIMPLE POLYGONAL ZOGCIA AND CRESCENTIC LUNARIA. JEWE LIME-
STONE (D1), BARON TOLL’S ESTATE.

. five zocecia may be counted in a length of 2 mm. Lunarium well

marked at the surface where it overarches the aperture slightly,
occupying about one-fifth of the wall, but not extending into the
zocecial cavity. The lunarium is quite distinct in tangential sections
but shows no additional characters to those noted at the surface.
Vertical sections exhibit a very short, thin-walled, immature zone in
which the zoecia are prostrate, and a longer mature region where
they are direct and have thicker walls. Diaphragms are thin and
very few or wanting entirely.

- The chief difference between this new species and the closely related
American form, Crepipora simulans Ulrich, lies in the size of the
zocecia. C. schmidti has four to five zocecia in 2 mm., while C. simu-
lans has seven in the same distance, thus making the diameter of the
former about one-half again as great. Another incrusting Russian
species, Crepipora lunatifera, from the Wesenberg formation, differs
in having still larger zocecia, more distinct crescentic lunaria with
their ends projecting into the noah cavity, and zocecia of an irregu-
larly angular shape.

88 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The specific name is in honor of the late Dr. Friedrich von Schmidt,
in appreciation of his life-long work upon the geology and paleontology
of the Russian Ordovician.

Occurrence.—Apparently rare in the Jewe limestone (D1), Baron
Toll’s estate, near Jewe, Esthonia.

Holotype —Cat. No. 57198, U.S.N.M.

CREPIPORA LUNATIFERA, new species.
Text fig. 27.
Zoarium forming a broad but thin crust upon foreign objects, with

the individual layers less than a millimeter in thickness. The type-
specimen consists of several fragmentary zocecia incrusting an exam-

Fig. 27.CREPIPORA LUNATIFERA. @, THE TYPE-SPECIMEN, INCRUSTING HORMOTOMA INSIGNIS (HICH-
WALD), TWO-THIRDS NATURAL SIZE; 0, VIEW OF THE ZO@CIA AT THE SURFACE, X9; ¢ AND d, TANGENTIAL
SECTIONS, X20 AND X35, ILLUSTRATING ZO@CIAL STRUCTURE; €, VERTICAL SECTION, X20, THROUGH THE
ZOARIUM. WHESENBERG LIMESTONE (HE), WESENBERG, ESTHONIA.

ple of the large gastropod Hormotoma insignis (Hichwald). The sur-
face of these zoaria is smooth with no conspicuously marked macule,
although groups of large zowcia clustered about a few mesopores are
present. Such groups, although easily overlooked, may be detected

pe 6 EEE

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 89

both at the surface and in tangential sections, by the fact that the
lunaria are directed away from their centers. The zoccia are
arranged in somewhat curved series about the macule, but this regu-
larity is obscured by the usually irregular shape of the apertures.
The latter may be said to be irregularly rhomboidal in outline as a
rule, with a small but very distinct crescentic lunarium at the proxi-
mal angle. With the introduction of an occasional mesopore, the
rhomboidal shape is destroyed and an irregularly angular aperture
results. Zocecial walls thin. Lunaria small, crescentic, with the
ends projecting into the zocecial cavity. Mesopores more numerous
than usual in the genus, averaging about one to every four zocecia.

In tangential sections the shape of the zocecia and the small, dis-
tinct, crescentic lunaria are the salient features. Vertical sections
show very simple zocecial tubes without tubule and with walls exhib-
iting the loose porous structure of the ceramoporoids.

The difference between this and the preceding species has been
mentioned under the description of the latter. No other incrusting
Russian Ordovician bryozoan has so distinct a lunarium, so.that this
character alone will aid in the recognition of C. lunatifera.

Occurrence.—Rare in the Wesenberg limestone (E) at the quarries,
Wesenberg, Esthonia.

Holotype.—Cat. No. 57199, U.S.N.M.

One specimen and a thin section of the type-specimen are in the
collections of the British Museum.

CREPIPORA INCRASSATA, new species.
Text fig. 28.

Zoarium massive, the type and only specimen being of an irregular,
discoidal shape, 13 mm. at its greatest height, and 40 mm. in its
longer diameter, composed of four superimposed layers of zoccia.
The upper ceiluliferous side is slightly convex, while the lower side,
which is uneven and somewhat wrinkled, shows either the bases of
the zocecia or their basal covering forming the epitheca. The cellu-
liferous surface is smooth and bears macule of mesopores, which,
although inconspicuous to the eye, are readily seen with a lens or in
thin sections. The zoccial apertures open upon the surface directly,
are polygonal in outline, have comparatively thick walls, with their
proximal fourth elevated and slightly arched over the cavity. This
overarching portion, the lunarium, is not distinctly separated from
the rest of the wall as in other species of the genus. An average
zocecium is 0.4 mm. in diameter but counting from a macula and
including the larger zocecia next to the cluster of mesopores, four and
one-half zocecia may be measured in 2 mm. Mesopores are present
but are confined to the maculz exclusively.

While the massive growth, large, thick walled, direct zocecia, with
broad, rather indefinite lunaria, are suflicient to recognize this species,

90 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

its most interesting characters are brought out in thin sections. In
tangential sections, the thick zoecial walls and the large, somewhat
undefined lunarial thickening, are characters which would be expected
from a study of the surface. The rounded cyst-like bodies seen in
zocecial tubes in vertical sections, are, however, most unexpected,
and are structures which are here noted for the first time in this
group of the ceramoporoid bryozoans. The significance of these
bodies and the bearing of this discovery upon the zoological position
of the whole group have been mentioned in the remarks under the
genus. I can only add here that their occurrence in the tubes as
well defined, rounded vesicles, distinct from the diaphragms and
attached at one side to the zoecial wall, is indicative of their physio-
logical importance. From comparison with recent species, they

ie
Fig. 28.—CREPIPORA INCRASSATA. @, EDGE VIEW OF THE TYPE-SPECIMEN, NATURAL SIZE; b, TANGENTIAL
SECTION, X20, SHOWING THE THICK WALLS AND OBSCURE LUNARIUM; C, VERTICAL SECTION, X10, CUTTING
TWO LAYERS OF ZOGCIA; d, PORTION OF A VERTICAL SECTION, X20, ILLUSTRATING OVICELL-LIKE BODIES
AND STRUCTURE OF WALLS. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

would seem to bear most resemblance to the ovicells of cyclostomatous
bryozoans.

Vertical sections also show the porous, laminated wall structure
and the thin, delicate diaphragms occurring in this genus. In the
present form the latter average their own diameter apart in the
mature portion. The massive zoarium, thick walled, polygonal
zocecia, large, indefinite lunarium, and, internally, the rounded
bodies occurring occasionally in the tubes, distinguish C. incrassata
from all other species of the genus.

Occurrence.—A single specimen was presented to the United States
National Museum by Dr. August von Mickwitz, who found it in the
Wassalem beds (D3) at Uxnorm, Esthonia.

Holotype.—Cat. No. 57200, U.S.N.M.

British Museum’s collections contain a fragment of the type-
specimen and thin sections.

+ i A OG Eee

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EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 91]

Genus ANOLOTICHIA Ulrich.

Anolotichia Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 381, 473; Geol. and Nat.
Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 326; Zittel’s Textbook of Pale-
ontology (Eng. ed.), 1896, p. 268.—NickLEs and Bassuer, Bull. 173, U. S.
Geol. Surv., 1900, p. 24.

Zoarium ramose, digitate, laminate, or incrusting; zocecial tubes
long, subpolygonal, intersected by remote diaphragms; lunarium
elevated at the surface, traversed by two to six minute, vertical,
closely tabulated tubes; mesopores sparingly developed.

Genotype ——Anolotichia ponderosa Ulrich. Earliest Silurian (Rich-
mond) of Illinois.

When this genus was established by Ulrich, the genotype and
another species were all that were known possessing the character-
istic minute lunarial tubes. Since then four or five new forms have
been identified in American strata, and these, with the new Russian
species here described, constitute a fair representation for the genus.
With the discovery of these additional species, the shape of the
zoarium pertaining to the genus has been extended to include para-
sitic and free explanate forms. Several writers have considered the
occurrence of minute tubuli traversing the lunarium longitudinally
a character of too little importance for generic recognition, but their
presence in at least eleven distinct species seems sufficient answer to
such criticism. Sardeson, in describing Anolotichia impolita, in his
discussion of the ‘‘Problem of the Monticuliporidea,’ ! seems to
regard the lunarial tubes as deceptive lucid spots at the tooth-like
points of the lunarium, and not distinct pores at all. I may be
misjudging him as his language is not clear to me, but, nevertheless,
it is a fact that distinct tubuli, varying from one to seven in different
species, do penetrate the lunarial walls and retain their structure no
matter whether the cells are filled with calcite or clay. Moreover,
these small tubes are crossed at frequent intervals by distinct tabulee,
an occurrence which I have verified in a number of instances and
which indicates to me that these pores certainly contained modified
polyps or were occupied by some other definite structure.

In its wall structure, Anolotichia is a typical ceramoporoid, and,
aside from the lunarial tubuli which form the most distinctive generic
character, the genus is closely related to Chiloporella and Orepipora,
Thin sections are almost always a necessity in distinguishing the
lunarial tubuli, although sometimes they may be seen distinctly
under a hand lens when the surface is rubbed smooth and then
shghtly etched with acid. Hitherto, mural pores, allowing communi-
cation between the zocecia as in Ceramopora, have not been observed
in Anolotichia, but their occurrence in several undoubted species of
the latter genus was discovered in the course of the present study.

1 Journal of Geology, vol. 9, Nos. 1 and 2, 1901, pp. 1, 149.
92602°— Bull. 77—11——8

92 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

ANOLOTICHIA RHOMBICA, new species.
Plate 2, fig. 9; plate 6, figs. 6, 7; text fig. 29.

Dianulites rhombicum Dysowsx1, Die Chaetetiden der Ostbaltischen Silur:
Formation, 1877, p. 33, pl. 1, fig. 9.

Not Chetetes rhombicus NicHouson, Quart. Journ. Geol. Soc. London, vol. 30,
1874, p. 507, pl. 29, figs. 11-110.

This well-marked form, for which I have adopted the specific name
applied to it by Dybowski, is a common and characteristic fossil of
the Wesenberg beds. It was intelligently described by Dybowski,
who, however, very erroneously considered it to be the same as
Nicholson’s Chetetes rhombicus. The latter is a synonym of Cheete-

Fig. 29.—ANOLOTICHIA RHOMBICA. a, TANGENTIAL SECTION, X20, WITH PORTION OF A MACULA REPRE-
SENTED; b, ANOTHER TANGENTIAL SECTION, X20, WITH THE LUNARIUM INCONSPICUOUS, BUT EXHIBITING
CONNECTING PORES; C, VERTICAL SECTION, X20, WITH STRUCTURE OF WALLS AND CONNECTING PORES
VISIBLE; d AND €, TWO PORTIONS OF A VERTICAL SECTION CUTTING THE WALLS BOTH VERTICALLY AND
LONGITUDINALLY, AND EXHIBITING THE CONNECTING PORES. WESENBERG LIMESTONE (E), WESENBERG,
ESTHONIA.

tes (now Rhombotrypa) quadrata Rominger, a very abundant ramose

trepostomatous bryozoan highly characteristic of the Richmond

group in North America. The only point of agreement between the
two species is the frequently rhombic shape of their zocecia, the one
character that misled Dybowski. Through the courtesy of Dr.

Mikhailowski, I have had the opportunity of studying an authentic

specimen, indeed probably the type-specimen, of Dybowski’s Dianu-

lites rhombicus, and I am, therefore, able to make the above identifica-
tion with certainty.

The zoarium of Anolotichia rhombica is of thin, free, undulating
masses with a wrinkled epitheca on the basal side and a smooth,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 93

celluliferous surface. The specimen shown on plate 6, figure 6, is
40 mm. in its greatest width, and does not exceed 2 mm. in thickness.
By the superposition of several layers of zoccia, the thickness of a
zoarium may reach as much as 6 or 8 mm. The celluliferous face
bears indistinct macule of zocecia slightly larger than the average at
regular intervals of about 4 mm., but such areas are best determined
by the radiate arrangement of the zocecia about them. The maculz
sometimes occupy the central portion of low, domelike elevations,
but a plain, smooth, celluliferous surface is of more frequent occur-
rence. Zocecia large, 4 to 5 in 2 mm., with thin walls and direct
subrhomboidal apertures. Mesopores few, with an occasional one
scattered among the zocecia, but most frequently restricted entirely
to the macule. Lunaria usually a well marked, erect crescent, situ-
ated in the acute angle of the zocecium, and directed away from the
maculz.

The essential features of the internal structure are believed to be
shown in the accompanying figures, so that it will only be necessary
to call attention to afew points. The vertical section is exceptionally
like that shown in explanate species of many other ceramoporoid
bryozoans, with the exception that the cell walls are pierced by
distinct connecting pores which give a beaded aspect to the walls.
None of the various vertical sections studied has shown a trace of
diaphragms, so that these are apparently wanting entirely. The
large connecting pores penetrating the zocecial walls are plainly
visible in both vertical and tangential sections, but especially in the
former. Their appearance in specimens with clay-filled zocecia is
shown in figures 29 ¢ to e, the pores themselves being occupied by
solid, earthy material and thus sharply marked off from the calca-
reous wall of the zocecium itself. When the zoccial tubes have been
filled with calcite, the pore is naturally not so distinctly visible,
although it can still be discerned without difficulty. In figure 29 ¢
the zocecial walls are cut across directly so that their edges only are
visible, but in figures 29 d and e, portions of the same section, the
flat side of a wall has been included in the section. The latter figures,
therefore, show transverse views of the pores in the shaded areas
and vertical sections of them in the remaining portions.

The occurrence of four to six tubules in each lunarium is the most
striking feature of tangential sections. Their appearance and the
general shape, size and position of the lunarium, are shown in figure
29 a. The rhomboidal shape of the zoccia so characteristic of sur-
face views is not as well marked in thin sections, especially where
mesopores are introduced. The aspect of part of a macula and its
surrounding zocecia is illustrated in figure 29 b. In both figures, the
disconnected walls showing here and there are indicative of the con-
necting pores so well shown in the vertical sections.

94 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Compared with other species of Anolotichia, the present form shows
most resemblance to A. revalensis, new species, from the Orthoceras
limestone. The latter, however, has distinctly larger polygonal
zocecia, practically no mesopores, and is decidedly more robust.
An undescribed form in the Rhinidictya bed of the Black River
(Decorah) shales at St. Paul, Minnesota, is probably the American
representative, differing mainly in having fewer lunarial tubuli.

Occurrence—Common in the Wesenberg limestone (E) at Wesen-
berg, Esthonia; also found in the Chasmops limestone at Ribeck and
Hulterstad Church, island of Oeland.

Cotypes—Cat. No. 57201, U.S.N.M.

Specimens and thin sections from Wesenberg and from the island
of Oeland are in the collections of the British Museum.

ANOLOTICHIA BREVIPORA, new species.
Text fig. 30.
The type-specimen of this species incrusted the inner side of the
living chamber of a cephalopod. In the process of weathering, the

shell has been completely removed, leaving the bryozoan with the
celluliferous side buried in the rock, and the basal membrane exposed.

Fic. 30.—ANOLOTICHIA BREVIPORA. @, VERTICAL SECTION, X20, EXHIBITING SHORT, IMMATURE, AND
MATURE REGIONS; 6, TANGENTIAL SECTION, X20, WITH TUBULES IN LUNARIA; C, PORTION OF SAME, X35,
SHOWING STRUCTURE OF LUNARIUM IN DETAIL. KUCKERS SHALE (C2), REVAL, ESTHONIA.

The surface characters of the species can not be figured at present,
but the thin sections show a structure so distinct from other species
that there should be little trouble in its identification. One especial
feature is the unusual tenuity of the zoccial layers, and the extreme
brevity of the mature and immature regions. While several layers

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 95

may be superposed and thus form masses a millimeter or more thick,
an individual layer is not more than 0.35 mm. thick. As illustrated
in figure 30 a, the vertical section shows a very short, thin-walled
immature region which passes almost directly into an equally short
mature zone, where the walls are thickened and assume the ceramo-
poroid structure, and mesopores are introduced. Tabule are wanting
in both regions.

The view shown in the tangential section, figure 30 b, is precisely
the same that can be obtained by examination of the celluliferous
surface after it has been slightly etched and moistened. The lunaria
are rather indefinite in themselves, but the occurrence of three or
four distinct lunarial tubes along the posterior third of the zoccial
wall plainly indicates their position. That the lunarium is present
and arises into an arch and that the tubuli are distinct structures
is shown in the lower part of figure 30 6, where the section has cut,
only the most elevated portions of the zoarium. The distinctness
of these tubuli and the indistinctness of the lunarium itself is further
illustrated in figure 30 c.

The zoccia are irregularly rhomboidal to subpolygonal, thin-walled,
and average 0.45 mm. in diameter. About four occur in 2 mm.
Mesopores are few, averaging less than one to a zoarium.

The extremely thin incrusting zoarium, thin-walled, polygonal
zocecia, indistinct lunaria, and quite distinct lunarial tubuli are char-
acters which separate Anolotichia brevipora from all other species of
the genus.

Occurrence.—Kuckers shale (C2), Reval, Esthonia.

Holotype-—Cat. No. 57202, U.S.N.M.

Fragments and thin sections of the type-specimen are in the col-
lections of the British Museum.

ANOLOTICHIA REVALENSIS, new species.

Plate 6, figs. 4, 5; text fig. 31.

Two well-preserved specimens, one an expansion of considerable
size and four or more millimeters in thickness, incrusting a large
gastropod, and a second smaller and much thinner example parasitic
upon a cephalopod, form the types of this new species. The thin
sections figured below are of the larger specimen, while the thin,
smaller example is illustrated on plate 6. While these two type
examples show a parasitic growth for the species, it is possible that
other specimens will prove to be free, lamellate expansions. Zoaria
of the latter method of growth commence as parasitic expansions,
which, with increasing size, become free.

The surface of this species is without conspicuous macular eleva-
tions, but the macule are distinctly visible areas 4 mm. apart, from
which the zoccia radiate. The zocecia are conspicuously large and

96 BULLETIN 77, UNITED STATES NATIONAL MUSEUM,

irregularly polygonal, with thin walls; three to four zowcia in 2
mm. The lunarium is comparatively small, occupying about one-
fifth of the zocecial wall, but it arises from one of the angles as a
distinct crescent, its ends projecting into the zoecial cavity, but
the structure as a whole not overarching it. Mesopores few, their
usual number being shown in the tangential section, figure 31 c.
Excepting that the tubes are of greater diameter on account of the
larger zocecia, the vertical section shows the same characters noted in
the description of Anolotichia rhombica. Connecting pores are pres-
ent but are not as numerous as in that species. The zoecial
walls are of considerable thickness compared with similar species and
show the laminated structure clearly. In addition to the points

Fic. 31.—ANOLOTICHIA REVALENSIS. @, VERTICAL SECTION, X9, WITH TWO LAYERS OF ZOGCIA; b, PORTION
OF THE SAME, X20, ILLUSTRATING LAMINATED WALL TISSUE; Cc, A NORMAL TANGENTIAL SECTION, X20.
ORTHOCERAS LIMESTONE (B3), REVAL, ESTHONIA.

pertaining to the zocecia, mentioned above, the occurrence of distinct
lunarial tubuli, varying in number from three to five, can be seen in
tangential sections.

Care is necessary in separating Anolotichia revalensis from the
similar A. rhombica, but it is believed that the larger size and irregu-
larly polygonal shape of the zocecia in the former are sufliciently
different from the smaller and more distinctly rhomboidal form of the
latter. The other explanate ceramoporoids have a zocecial structure
which is not comparable to that of the present species.

Occurrence.—Apparently uncommon in the Orthoceras limestone
(B3) at Reval, Esthonia.

Cotypes.—Cat. No. 57203, U.S.N.M.

British Museum collections, specimen and thin section.

HARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 97

ANOLOTICHIA IMPOLITA (Ulrich).
Plate 7, fig. 11; text figs. 32, 33.

Crepipora impolita Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minne-
sota, 1886, p. 77.

Anolotichia impolita Unricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 327, pl. 28, figs. 15-20; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 268, fig. 437 A-C.—SarpzEson, Journ. Geol., vol. 9, 1901, p. 13, pl. A,
fig. 12.

In the collections made by Prof. Schuchert from the Kuckers
shale, on Baron Toll’s estate, are five small, ramose bryozoans which
have all of the characters of young specimens of the abundant
American form Anolotichia impolita. The only differences I can
point out in the Russian specimens are, first, a slight decrease in the
size of the zoecia; second, a slightly obliquely directed lunarium; and,
a b

Fig. 32.—ANOLOTICHIA IMPOLITA. @ AND 0, SURFACE OF A WELL-PRESERVED EXAMPLE, X9, AND X18; c,
SMALL PORTION OF A TANGENTIAL SECTION, X18, SHOWING LUNARIA AND TUBULI; d, VERTICAL SECTION, X9.
STICTOPORELLA BED OF BLACK RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.)

third, a less polygonally outlined zocecium. However, as all of these
specimens have a very narrow, mature region, and the zoarium itself
is small, there is little doubt that they are only young stages of a
species growing into more robust branches. Almost all of the
American specimens of Anolotichia wmpolita are of heavy, full-grown
zoaria, but a few examples before me show the youthful condition.
After carefully comparing these and the Russian specimens, I am
convinced that more mature fragments of the latter could not be
distinguished even as a variety from the American species. Both the
American and Russian examples are illustrated here, and comparisons
of figures 32 and 33 will show their identity of structure.

Ulrich’s description of the species is as follows:

Zoarium large, bushy, consisting of abundantly and irregularly divided solid
branches, the latter varying from 5 to over 20 mm. in diameter. At the base the

branches may coalesce, and here they are always stronger than at their terminations.
Rarely the zoarium is not branched, but occurs as an irregular mass with lobe-like

98 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

excrescences. Zocecia large, with moderately thin walls, direct, hexagonal or sub-
rhomboidal apertures. The latter are subequal (there being no distinguishable
clusters of large ones), are arranged in rather regular series with 1lin5mm. Lunarium
well developed, appearing as a small crescentic elevation usually in one of the angles.
Mesopores few, sometimes appearing to be absent entirely, occasionally forming small
clusters of from two to six.
Internal characters.—In tangential sections the walls of contiguous zocecia appear to
be thoroughly amalgamated, the lunarium is represented by two or three small lucid
spots (lunarial tubuli) on one side of the tube, the end ones projecting slightly into
its cavity. In vertical sections the tubes are scarcely to be called vertical even
in the axial region, curv-
ing outward with a uni-
form curve from the be-
ginning. Their walls are
composed ofrapidly alter-
nating dark and lighter
shades of schlerenchyma,
so that they appear more
or less distinctly lineate
transversely. ‘The cause
of these lines, which are
closest in the peripheral
part of the zoarium, is
unknown, unless the light
ones, which are of uni-
form width and, espe-
cially in the axial region,
narrower than the dark

bands, represent rows of

Fig. 33.—ANOLOTICHIA IMPOLITA. d@, FRAGMENT OF ZOARIUM, NATURAL fs
SIZE; b AND ¢, TANGENTIAL AND VERTICAL SECTIONS, X18, INTRODUCED perforations. , Exce ed 7
FOR COMPARISON WITH FIGURE 32. KUCKERS SHALE (C2), BARon 108 ly delicate dia-
TOLL’S ESTATE, ESTHONIA. phragms, their diameter

or more apart, occur
chiefly in the outer and middle part of the tubes. The axial portion of transverse
sections is very nearly like tangential, the only difference being that the walls are
a little thinner and small tubes comparatively more abundant.

Occurrence.—Very abundant in the Stictoporella bed of the Black
River (Decorah) shale at various localities in Minnesota and Iowa.
Rather uncommon in the Kuckers shale (C2), Baron Toll’s estate,
near Jewe, Esthonia.

Plesiotype.—Cat. No. 57204, U.S.N.M.

One specimen from Baron Toll’s estate is in the collection of the
British Museum.

ANOLOTICHIA SACCULUS, new species.
Text fig. 34.

Zoarium a small, sack-like body, narrow at the lower end, broad in
the upper portion. The two type-specimens are of about equal size,
but the more perfect one, shown in figure 34a, is about 15 mm. high and
12 mm. at its greatest width. The zoccial layer forming this hollow
body is less than a millimeter in thickness, with the zocecial apertures

EARLY PALEOQZOIC BRYOZOA OF THE BALTIC PROVINCES. 99

opening «2 the outer side, and the inner, noncelluliferous face bearing
a veil wrinkled epitheca. The two specimens known were broken
from the solid rock so that most of the zocecial layer adhered to the
matrix and left the clay filled central space with a mold of the epith-
eca to represent the zoarium. In figure 34 a, a portion of the
zocecial layer itself is seen adhering to the clay mold, which, however,
represents the shape of the zoarium equally well.

Surface of zoarium smooth, macule inconspicuous, but, as in other
species of the family, readily determined by the radial arrangement
of the zocecia about them. At the surface the zocecia are subrhom-
boidal in outline, have rather thick walls which bear a small, distinct

Fig. 34.—ANOLOTICHIA SACCULUS. @, A TYPE-SPECIMEN, NATURAL SIZE, WITH MOST OF THE ZOARIUM
EXFOLIATED AND SHOWING THE IMPRESSION OF THE EPITHECA; b, VERTICAL SECTION, X20; c, TANGEN-
TIAL SECTION, X20, SHOWING NUMEROUS MESOPORES AND INDISTINCT LUNARIA; d, ANOTHER TANGENTIAL
SECTION, X20, WITH THE NORMAL OCCURRENCE OF LUNARIA AND TUBULI; €, TWO LUNARIA, X35, EXHIBIT-
ING NUMBER AND DISTRIBUTION OF TUBULI. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

lunarium in the acute angle; about four zowcia in 2mm. The luna-
rium occupies about one-fifth of the apertural wall and bears four or
five of the tubules characterizing the genus. Mesopores are few at
the surface, averaging about one to a zocecium (see fig. 34 d), but
deep tangential sections show them in comparative abundance (fig.
34). Insuch sections the zocecia are oval-shaped and the lunarium
is poorly developed. Vertical sections show the characteristic
lamination and porous structure of the walls common to all ceram-
oporoids, and in addition indicate that diaphragms are absent.

The hollow form of growth is sufficient to distinguish the present
species from others of the genus, although other differences may be
noted by comparing the figures with those of the other species of
Anolotichia here described.

100 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Occurrence.—Kuckers shale (C2), Baron Toll’s estate, Esthonia.

Cotypes.—Cat. No. 57205, U.S.N.M.

A thin section of one of the type-specimens is in the collection of the
British Museum.

Genus FAVOSITELLA Etheridge and Foord.

Favositella ErHERIDGE and Foorp, Ann. and Mag. Nat. Hist., ser. 5, vol. 13,
1884, p. 472.

Bythotrypa Uuricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
324; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 268.—NicKLES
and BassteEr, Bull. 173, U.S. Geol. Surv., 1900, p. 24.

Specimens of the type-species of the genus Favositella have recently
come into the possession of the National Museum, and, upon being
sectioned, have proved to belong to the same generic group well
described by Ulrich under the name of Bythotrypa. The figures by
Etheridge and Foord illustrating the internal structure are accurate
and sufficient for the identification of the species, but the title of
their article and their description of the genus, written evidently
with the supposed relationship of Favositella to Favosites in mind, are
so misleading that the identity of Bythotrypa and Favositella has
hitherto not been noted. With the two described species of Bytho-
trypa, several new American forms, the three species described in the
present paper, and the type-species of Favositella, as well as one or
two undescribed forms from the European Silurian, Favositella
attains a specific representation equal to that of many of the other
ceramoporoid genera.

The authors of Favositella recognized distinct ‘‘mural pores of a
large size, remote and irregularly disposed” in their thin sections,
which caused them to consider the genus as related to Havosites.
They further state that ‘‘in some specimens the mural pores have
been filled with chalcedony of a concentric structure. It may be
noted that the pores are so large as to be seen on a polished surface.”
The specimens and thin sections used in my study of Favositella
wnierpuncta, the type-species, show these same pore-like structures,
but I am unable to recognize them as pores for the very simple reason
that in sections they appear, not in the zocecial tissue or penetrating:
the walls, but isolated in the zoecial cavity. Thus, in a tangential
section, these ‘‘pores’’ may be seen as individual, round bodies in the
clay-filled zocecial cavity, or in the mesopores, with no relation to the
walls. From their position and composition it is evident that they
have nothing to do with the bryozoan itself, but are simply rounded,
siliceous bodies included in the other material filling the cell cavity.
The appearance of these included bodies in thin sections is shown at
¢ in figure 35.

Curiously enough, mural pores do exist in this species, as is indicated
in the accompanying figures of a tangential and a vertical section.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 101

They are most apparent in the latter because more opportunity 1s
afforded to show them as they pierce the walls. However, these
‘pores do not differ from the usual pores seen in other ceramoporoid
genera, so that their occurrence can not be considered as an important
generic characteristic. The minute structure of the zocecia in F.
interpuncta, the style of lunarium, arrangement and occurrence of
mesopores, is precisely the same as in Bythotrypa laxata, the genotype
of Bythotrypa. Moreover, each species has the same internal struc-
ture, particularly the loose, irregular, vesicular tissue formed by
mesopores.

Ulrich has given a clear, concise definition of Bythotrypa which I
quote, as it applies without change to the genotype of Favositella.

FIG. 35.—FAVOSITELLA INTERPUNCTA. @, VERTICAL SECTION, X20, SHOWING THE LOOSE VESICULAR-LIKE
TISSUE DEVELOPED IN THE MATURE REGION, THE PORES CONNECTING ADJOINING ZOG@CIA AND AN INCLUDED
CONCENTRIC BODY AT Cc; b, TANGENTIAL SECTION, X20, WITH STRUCTURE OF ZOGECIA AND MESOPORES AND
ONE OF THE INCLUDED SILICEOUS BODIES AT c. WENLOCK SHALE, WENLOCK, ENGLAND.

Zoaria massive or lamellate. Zocecia forming long continuous tubes, intersected
by thin diaphragms, their walls minutely crenulate and with thestructure character-
izing the ceramoporoids. Lunarium well defined, large, projecting above the rest of
the aperture margin. Mesopores numerous, open at the surface, interiorly forming a
species of vesicular tissue unusually loose and irregular in construction.

The loose, irregular vesicular tissue formed by the mesopores is the
character most relied upon in separating species of Bythotrypa, or,
as they should now be designated, Favositella. This tissue is similar
to the vesicular filling of the interzoccial spaces in the Fistuliporide.
As remarked by Ulrich, Bythotrypa represents probably a premature
evolution of the fistuliporoid type that either became extinct or was
reabsorbed into the parent stock. The Silurian occurrence of the

102 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

genus in rocks containing typical Fistuliporide would suggest that
it represents a more permanent line of development, possibly giving
rise to such genera as the Devonian Pinacotrypa.

Genotype.—Favositella interpuncta (Quenstedt).1 Silurian (Wen-
lock shale) of England.

FAVOSITELLA EXSERTA, new species.
Text fig. 36.
Zoarium a lamellate expansion several centimeters in width and

usually about 4 mm. thick. Under surface, as usual in such forms
of growth, wrinkled and covered with an epithecal membrane.

Fig. 36.—FAVOSITELLA EXSERTA. @, EDGE VIEW OF A ZOARIUM, NATURAL SIZE, IMBEDDED IN THE ROCK; D,
SURFACE VIEW, X9, OF THE SECTIONED TYPE; C, TANGENTIAL SECTION, X20, EXHIBITING THE SMALL PROM-
INENT LUNARIUM; d, VERTICAL SECTION, X9, THROUGH PORTIONS OF TWO LAYERS; €, PORTION OF THE
SAME, X20, ILLUSTRATING WALL STRUCTURE IN MORE DETAIL. KUCKERS SHALE (C2), BARON TOLL’S
ESTATE, ESTHONIA.

Zoccial apertures rather large, direct, subpolygonal, and nearly
equal in size, 0.47 mm. in diameter, on the average with three to four
in 2mm. Lunarium small, occupying less than one-seventh of the
zocecial wall, but so sharply elevated that it is a prominent surface
‘feature. Walls of both zoccia and mesopores quite thin. Meso-

1 Favosites interpuncta Quenstedt, Petref. Deutschl., Abth. 1, 1881, p. 10, pl. 148, fig. 9.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 103

pores irregularly angular, of variable size, sometimes nearly as large
as the zoccia, and frequently abundant enough to surround a zocw-
cium. They are most abundant in the macule which are developed
at more or less regular intervals, but are not a conspicuous surface
feature.

In tangential sections the thin-walled cells with the small, although
well developed, thick, crescentic lunarium form the important fea-
ture. Vertical sections show less important specific characters,
although here the generic characters are best illustrated. These are,
first, the ceramoporoid wall structure with small mural pores and
fine, transversely laminated tissue, and, second, the loose vesicular
structure formed by the mesopores. A few thin diaphragms occur
in the tubes. The vesicular structure is formed by the great irregu-
larity of the mesopore walls, allowing them at times to coalesce.
Sometimes an oblique or irregularly placed tabula occurs in the
mesopores and by its position increases the vesicular appearance.

The small but sharply elevated lunarium externally, and the loose,
vesicular internal structure, are diagnostic of the species.

Occurrence.—Apparently common in the Kuckers shale (C2), Baron
Toll’s estate, near Jewe, Esthonia.

_ Holotype.—Cat. No. 57177, U.S.N.M.
Specimens and thin sections in the collections of the British Museum.

FAVOSITELLA DISCOIDALIS, new species.
Text fig. 37.

Cir. Bythotrypa laxata Uuricu, Geol. and Nat. Hisv. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 325, pl. 28, figs. 21-25.

Zoarium a small, discoidal mass, with a concentrically wrinkled
epitheca on the flat basal side, and the upper surface slightly convex.
None of the specimens examined exceeds 20 mm. in diameter and
6 mm. in height. The zoecial apertures open directly at the sur-
face, are large, nearly equal in size, and range in shape from subovate
to obscurely polygonal. An average single zowcium is 0.6 mm. in
diameter, with three usually occurring in 2 mm. The lunarium,
although clearly developed and occupying nearly one-fourth of the
zocecial circumference, overarches the aperture but slightly. Meso-
pores few for the genus, the number shown in the accompanying
illustrations (figs. 37 c, d) being the maximum seen. Seldom do the
mesopores attain the size of the zocecia from which they can always
be distinguished when almost as large, by the absence of a lunarium.
As in other species of the genus, the mesopores, at more or less regular
intervals, cluster together and form macule, which, however, in the
present form, are small and inconspicuous. ;

In tangential sections the zocecia are seen to vary from subangular or
polygonal to subovate in outline, their shape being determined by the

104 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

number of intervening mesopores. The mesopores are usually small,
irregular in shape, and few in number. Both zocecia and mesopores
have thin walls which have the indefinite structure characteristic of
the Ceramoporide. The lunarium is ill-developed in some of the
zocecia and at best it appears only as a thickened border occupying
the posterior fourth of the zocecial walls, and with its ends not pro-
jecting into the zowcial cavity. Where the lunarium is apparently
absent, its place is indicated by the regularly curved form of the
zocecial wall, the opposite portion of the zocectum being angular or
less uniformly curved. Sometimes additional layers of light-colored
tissue are deposited upon the lunarium, adding to its distinctness in
tangential sections.

Fig. 37.—FAVOSITELLA DISCOIDALIS. @ AND b, TOP AND SIDE VIEWS OF A ZOARIUM, NATURAL SIZE; C, SUR-
FACE OF SAME, X9; d, TANGENTIAL SECTION, X20; ¢ AND/, VERTICAL SECTION, X9, ILLUSTRATING SLIGHT
VARIATION IN STRUCTURE. ECHINOSPHERITES LIMESTONE (C1), KATLINO, GOVERNMENT OF ST. PETERS-
BURG. ‘

The characteristic loose vesicular structure is somewhat incom-
pletely developed in the present species, mainly because of the small
size of the zoarium. It is clearly indicated, however, in the vertical
sections figured. Thin diaphragms are developed in the tubes at
intervals slightly greater than their own diameter.

The present form is probably most closely allied to Favositella
laxata (Ulrich), which holds approximately the same stratigraphic
position in America. Favositella laxata differs, however, first in
forming quite large zoaria, second, in having smaller zoccia (the
average zocecium being 0.4 mm.in diameter), and, finally, in possessing
more numerous mesopores. The tabulation and other internal fea-
tures of both species are practically identical. Compared with asso-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 105

ciated bryozoans, there are several species with a similar method of
growth, but none of them has the internal vesicular tissue. The
species is represented by only a few specimens, all of which are small.
It is possible that, with more examples, the resemblance to F. lazata
will be found such that F. discoidalis may be considered only as a
variety. At any rate, the two forms are closely related.

Occurrence-—Apparently rare in the Echinospherites limestone (C1)
at Katlino and at Pulkowa, government of St. Petersburg.

Holotype.—Cat. No. 57176, U.S.N.M.

Sections of the type-specimen are in the British Museum.

FAVOSITELLA ? PUNCTATA, new species.
Text fig. 38.

Cir. Archeopora punctata E1cHwa.p, Letheea Rossica, vol. 1, 1860, p. 406, pl. 24,
fig. 19.

This interesting bryozoan is undoubtedly a member of the Ceramo-
poridz, but its generic position is a matter of less certainty. Asa
provisional arrangement, I have placed it under Favositella, recog-
nizing the fact that future studies will most probably cause its refer-
ence elsewhere.

Fic. 38.—FAVOSITELLA? PUNCTATA. @, CELLULIFEROUS SIDE OF A ZOARIUM, X2, WITH THE ELONGATED,
ALMOST CONFLUENT MACUL; 6b, BASAL SIDE OF SAME SPECIMEN, X2, SHOWING ATTACHMENT TO A SMALL,
RAMOSE BRYOZOAN; C, TANGENTIAL SECTION, X20; d, VERTICAL SECTION, X20. WASSALEM BEDS (D3),
UxXNORM, ESTHONIA.

The zoarium is thin and explanate, beginning growth upon some
foreign object, as the ramose bryozoan shown in figure 38 6, and con-
tinuing until a lamellate, epithecated expansion, a centimeter or
more in diameter, and several millimeters thick results. The cellu-
liferous surface presents no monticules or tubercules, but is uneven
because of the narrow, slightly depressed, elongated macule, which
are bare of apertures and are often almost confluent. Apertures

106 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

irregularly rounded with the posterior fourth slightly raised to form
the lunarium, which, however, is not conspicuous either at the sur-
face or in sections. The average aperture is 0.38 mm. in its longer
diameter and 0.30 mm. wide; four occur in 2 mm. Interzoccial
spaces solid, showing no trace of mesopores.

Tangential sections show irregularly rounded to oval zocecia, with
evidence of the lunarium at their posterior end. Mesopores are
absent, the interzocecial spaces being filled with a solid tissue which,
in vertical sections, is seen to be of the usual laminated type common
to the Ceramoporide. In the short, immature regions the zocecia
have especially thin walls. Diaphragms are wanting in both regions.

The lamellate zoartum with its conspicuous, elongate, solid maculee
externally, and the solid, zocecial interspaces of laminated tissue seen
in sections, will serve to distinguish the present species from all other
Ordovician forms. Certain unplaced ceramoporoids from the Silurian
seem to have a similar structure, but, as they are undescribed, com-
parisons are unnecessary.

Hichwald’s figures of Archeopora punctata have a slight resemblance
to Favositella? punctata, and it is for the reason of their possible
synonymy that I have selected the same specific name for the latter.
Notes on Archeopora punctata are given on a later page of this work.

Occurrence.—Not uncommon in the Wassalem beds (D3) at
Uxnorm, near Reval, Esthonia.

Holotype.—Cat. No..57178, U.S.N.M.

Specimens and thin section in the collections of the British Museum.

Genus SPATIOPORA Ulrich.

Spatiopora Uxricx, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 155; vol. 6,
1883, p. 166.—Foorp, Contr. Micro-Pal. Cambro-Sil., 1883, p. 20.—MILLER,
North Amer. Geol. and Pal., 1889, p. 323.—Utricu, Geol. Surv. Illinois,vol.
8, 1890, p. 381; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
319; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 269.—NicKLEs and
BasstER, Bull. 173, U. 8S. Geol. Surv., 1900, p. 24.—BassiEr, Bull. 272,
U.S. Geol. Surv., 1906, p. 21.—Cuminas, Thirty-second Ann. Rep. Dep. Geol.
Nat. Res. Indiana, 1907, p. 756.—Hennia, Archiv fur Zool., vol. 4, No. 21,
1908, p. 12.

The single species of this genus noted in the Russian strata is so
like an American form that it has not been differentiated. S—patio-
pora, briefly defined, is a ceramoporoid genus in which the character-
istic wall structure is present, but mesopores and lunaria are prac-
tically absent. The zoarium is usually found incrusting the shells of
Orthocerata, and the zocecia, as a whole, show great resemblance to
the Trepostomata.

Genotype.—Spatiopora aspera Ulrich. Upper Ordovician (Mays-
ville) of the Ohio Valley.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 107

SPATIOPORA LINEATA INCEPTA Ulrich.

Plate 7, figs. 9, 10.

Spatiopora maculosa var. incepta Utricu, Geol. Nat. Hist. Surv. Minnesota, vol.
3, pt. 1, 1893, p. 320.

Spatiopora lineata-incepta NicKLES and BassuER, Bull. 173, U. 8. Geol. Surv.,
1900, p. 407.

The Black River (Decorah) shales of Minnesota have yielded sev-
eral examples of a species of Spatiopora which was briefly defined by
Ulrich as S. maculosa var. incepta. Further study of these specimens
showed that they might be classed with more reason as a variety of
the middle Cincinnatian form, S. lineata Ulrich. The zoarium of
both the Russian and American specimens is a thin crust spread over
shells of Orthoceras (Pl. 7, fig. 9). The surface is smooth, but under
a hand lens numerous blunt acanthopores are occasionally seen.
Maculz are present at regular intervals and contain the only meso-
pores which occur. The zoccia are thin-walled and have little to
distinguish them from simple incrusting Trepostomata. Thin sec-
tions, however, show the characteristic ceramoporoid structure.

Occurrence.—Rare in the upper Black River (Decorah) shales at
Chatfield, Minnesota, and in the Wesenberg limestone (E) at Wesen-
berg, Esthonia.

Plesiotype.—Cat. No. 57206, U.S.N.M.

Genus SCENELLOPORA Ulrich.

Scenellopora Uuricn, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 150.—
Miter, North Amer. Geol. and Pal., 1889, p. 322.—Uxricu, Geol. Surv.
Illinois, vol. 8, 1890, p. 368; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 268.—Simeson, Fourteenth Ann. Rep. State Geologist of New York
for the year 1894, 1897, p. 593.—NicKLEs and Basser, Bull. 173, U.S. Geol.
Surv., 1900, p. 24. ;

This genus was established for a simple, pedunculate, ceramoporoid
bryozoan from Middle Ordovician strata of eastern Tennessee. In
the type and only described species the upper surface is slightly con-
cave and celluliferous, the zoccial aperture occupying the summits
of low ridges radiating from the center. A second species with surface
characters much as in Eichwald’s Ceramopora socialis is known from
the same strata holding the type. This new species and C. socialis
both agree in being parasitic, differing in that respect from the geno-
type, and causing, therefore, a slight revision in the generic diagnosis.

Genotype.—Scenellopora radiata Ulrich. Middle Ordovician of
Tennessee.

92602°—Bull. 77—11——9

108 BULLETIN 17, UNITED STATES NATIONAL MUSEUM.

SCENELLOPORA SOCIALIS (Eichwaild).
Text fig. 39.
Ceramopora socialis E1cawaup, Letheea Rossica, vol. 1, 1860, p. 412, pl. 26, fig. 21.

A single well-preserved specimen incrusting an Echinospherites in
the collection before me agrees so well with Hichwald’s figure of
Ceramopora socialis that I have no doubt of its identity. The first
clue to the identification of this species is the distinctness of the sey-
eral croups of zocecia with their central, solid areas, growing together
as a parasitic expansion. Hach of these groups, when magnified, is
seen to consist of a ma-
cula free from cell open-
ings, from which zoccia
with strongly elevated lu-
nariaradiate. Thelunaria
encircle the posterior three-
fourths or more of the
zocecial apertures, and are

Fic. 39.—SCENELLOPORA SOCIALIS. @ AND b, COPY OF EICH- distinctly arched. Kich-

WALD’S VIEWS OF CERAMOPORA SOCIALIS; @, ZOARIUM, NAT- wald’s floure of the surface
URAL SIZE, INCRUSTING AN ECHINOSPHERITES; b, ONE OF THE ; : 3

GROUPS OF ZOG@CIA OF THE SAME, ENLARGED. ECHINOS- enlarged 1S imcorrect In.
PHERITES LIMESTONE (C1), PULKOWA, GOVERNMENT OF ST. showing the elevated lu-
PETERSBURG.

narial walls as completely
surrounding the cell opening. Measuring along one of the radiating
rows of zocecia, about four apertures occur in 2 mm.

The incrusting zoarium of small groups of zocecia with well-devel-
oped, arched lunaria will readily distinguish this from all associated
bryozoans.

Occurrence.—Apparently rare in the Echinospherites limestone -
(C1) at Poulkowa and Katlino, government of St. Petersburg.

Plesiotype.—Cat. No. 57207, U.S.N.M.

Family FISTULIPORIDA Ulrich.

This family comprises a number of genera quite similar in their
general characteristics to the members of the Ceramoporide, but dif-
fering conspicuously in having the zoecial interspaces occupied by
vesicular tissue. This difference is not merely one of convenience in
classification but is a natural one, as shown by the history of the two
families. The Ceramoporide are almost restricted to the Ordovician,
while the Fistuliporide are highly characteristic of the later Paleozoic
rocks. With the exception of one or two undescribed primitive spe-
cies of Fistulipora in the Middle Ordovician strata of the Appa-
lachian Valley, the following species are the only Ordovician repre-
sentatives of the family. Hach, as would be expected, is a primitive
member of its genus.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 109
Genus FISTULIPORA McCoy.

Fistulipora McCoy, Ann. and Mag. Nat. Hist., ser. 2, vol. 3, 1850, p. 131.—Mrne-
Epwarps and Hare, Pol. Foss. Terr. Pal., 1851, p. 219.—Mitnz-Epwarps,
Hist. Nat. des Corall., vol. 3, 1860, p. 238.—Nicwotson, Pal. Prov. Ontario,
1874, p. 63.—DyBowsk1, Verh. Mineral. Gesell. St. Petersburg, vol. 10, 1876,
p. 180.—NicHotson, Pal. Tabulate Corals, 1879, p. 292; The Genus Monticu-
lipora, 1881, p. 91.—NicHotson and Foorp, Ann. and Mag. Nat. Hist., ser.
5, vol. 16, 1885, p. 500.—Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp.-382,
474.—NIckKLEs and Basster, Bull. 173, U. 8. Geol. Surv., 1900, pp. 25, 266.—
BAssLER, Bull. 292, U.S. Geol. Surv., 1906, p. 22.—Hzennic, Archiv fur
Zool., vol. 4, No. 21, 1908, p. 16.

Didymopora Utricx, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 156.

Dybowskia WAAGEN and Picut, Pal. Indica, ser. 13, 1886, pp. 717.

Dybowskiella WAAGEN and WENTZEL, Pal. Indica, ser. 13, 1886, pp. 910, 916.

Lichenaha (not Hall, 1852) Hatt and Simpson, Nat. Hist. New York, Pal., vol. 6,
1887, p. xvi.—Mitier, North Amer. Geol. and Pal., 1889, p. 311.—Simpson,
Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897,
p. 559.

Fistuliporella Simpson, Fourteenth Ann. Rep. State Geologist New York for the
year 1894, 1897, p. 560.

Zoarium ranging in the various species from incrusting to massive
and subramose. Zocecia more or less rounded with a distinct luna-
rium. Interzocecial spaces smooth or granulose at the surface,
occupied internally by one or more series of vesicles.

Genotype.— Fistulipora minor McCoy. Carboniferous of England.

The following new species can not be considered anything else than
a primitive Fistulipora. It possesses the generic characters of a
lunarium and vesicular interspaces, but the lunarium is poorly out-
lined, and, indeed, when best shown it appears as only a broad curve
at one end of the cell. The vesicular interspaces also at times have
the tabulated aspect of the mesopores in some of the ceramoporoids.

FISTULIPORA PRIMVA, new species.

Text fig. 40.

Zoarium a small, elongate, dome-shaped mass, 12 mm. in height
and 9 mm. wide. Surface smooth and exhibiting large, rounded
zocecial apertures, isolated from each other by closed interspaces.
Distinct maculz of closed mesopores and larger zocecia on a plane
with the surface, at intervals of about 4 mm., measuring from center
to center. Zocecial apertures irregularly rounded, averaging 0.36
mm. in diameter, with three in 2mm. Lunarium represented by an
obscure broad curve occupying the anterior third of the cell wall, little
raised above the general surface. Interspaces averaging the zoccial
diameter in width, closed at the surface by a thin covering through
which the openings of the vesicular species are indistinctly visible.
Large, distinct granular spines dot the surface of these spaces and
sometimes occur on the cell wall.

110 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In thin sections the large granules of the surface are seen to be the
ends. of continuous thick acanthopore-like tubes composed of a
granular, black material quite different in structure from the usual
wall substance. These tubes follow the walls in their course to the
surface, but they are not limited to any particular tube or direction.
In some sections they are seen to cross diagonally from one side of a
cell wall to the other before reaching the surface. Tangential sections

Fic. 40.—FISTULIPORA PRIMHVA. @, THE TYPE-SPECIMEN, NATURAL SIZE; 0, SURFACE OF SAME, X8, EXHIB-
ITING A PORTION OF A MACULA AND SURROUNDING ZOGCIA; C, TANGENTIAL SECTION, X20, SHOWING OBSCURE
LUNARIUM AND NUMEROUS LARGE GRANULES; d, VERTICAL SECTION, X8; €, PORTION OF SAME SECTION,
X20. GLAUCONITE LIMESTONE (B2), PAWLOVSK, GOVERNMENT OF ST. PETERSBURG.

show irregularly rounded zocecia with thin walls separated by vesic-
ular areas with equally thin walls. Here the lunarium is as indis-
tinctly developed as at the surface, while the granular tubes are just
as clearly shown.

The fistuliporoid vesicles and the large, dark granular structure of
this speciés are so unusual in an Ordovician bryozoan that compari-
sons with other species are unnecessary.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 111

Occurrence.—Rare in the Glauconite limestone (B2) at Pawlovsk,
government of St. Petersburg.

Holotype.—Cat. No. 57208, U.S.N.M.

A thin section of the type-specimen is in the collection of the British
Museum.

Genus CHILOTRYPA Ulrich.

Chetlotrypa Unricu, Journ. Cincinnati Soc. Nat. Hist., vol. 7, 1884, p. 49.

Chilotrypa Mitter, North Amer. Geol. and Pal., 1889, p. 297.—Utricn, Geol.
Surv. Illinois, vol. 8, 1890, p.382; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 269.—Srueson, Fourteenth Ann. Rep. State Geol. New York for the
year 1894, 1897, p. 554.—NickiEs and Basser, Bull. 173, U.S. Geol. Surv.,
1900, p. 26.—BassteEr, Bull. 292, U.S. Geol. Surv., 1906, p. 24.

The zocecial characters of this genus are essentially the same as in
Fistulipora, but the zoarium is of small, ramose branches with a
narrow, irregularly expanding and contracting axial tube. The
genus may be said, therefore, to be the equivalent in the Fistuli-
poridee of Caloclema in the Ceramoporide. The following species
is the earliest known, and naturally has primitive characters.

Genotype.—Chilotrypa hispida Ulrich. Mississippian of the United
States.

CHILOTRYPA IMMATURA, new species.

Text fig. 41.
Zoarium of very narrow, irregularly cylindrical, smooth branches,

about 1 mm. in diameter, with small, macular areas at intervals of
2.5 mm. Apertures with their proximal end slightly raised into a

Fic. 41.—CHILOTRYPA IMMATURA. @, A FRAGMENT, X2, WITH A FEW ZOCCIAL APERTURES ENLARGED; 3,
TANGENTIAL SECTION, X20, SHOWING ARRANGEMENT AND SHAPE OF ZOG@CIA; c, VERTICAL SECTION, X20,
WITH EXPANDING AND CONTRACTING CENTRAL TUBE; d, TRANSVERSE SECTION, X20, SHOWING CENTRAL
TUBE AND THICKNESS OF ZOARIAL LAYER. LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND OF DAGo,
EsTHONIA.

lunarium, arranged in ascending spiral rows, elongate oval, five in
2mm, Interzoccial spaces closed at the surface. Ends of branch
show the hollow, axial tube, about 0.16 mm. in diameter. The tube
is a prominent feature of vertical sections, where it is seen to slightly
expand and contract. Suchsections also show the zocecia to arise from

112 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

the basal membrane or epitheca forming the wall of this tube, and
to proceed to the surface in a gentle curve. In the immature region
their walls are thin and diaphragms are absent. In the mature zone
the walls thicken, interzocecial spaces are developed, and an occasional
diaphragm is inserted. In well-developed species of Chilotrypa the
interzocecial spaces are filled with vesicles precisely as in Fistulipora,
but in the present form the vesicles are almost entirely absent and
their place is occupied by laminated tissue similar to that occurring
in the more primitive Ceramoporide. Tangential sections exhibit
elongate oval zocecia with a slight lunarial thickening at the proximal
end.

The delicate cylindrical branches with a small, central axial tube,
and small, elongate apertures arranged in ascending spirals, are
different enough from all other bryozoans to require no comparisons.
While the species has some resemblance to Celoclema, it is believed
that the majority of its characters show it to be a primitive form of
Chilotrypa.

Occurrence.—Apparently rare in the Lyckholm limestone (F1) at
Kertel, island of Dago.

Holotype.—Cat. No. 57209, U.S.N.M.

British Museum, thin sections of type-specimen.

Order CRYPTOSTOMATA Vine.

This order of the Bryozoa was proposed by Vine in 1883 as a sub-
order to include mainly the bifoliate ptilodictyoid genera. Since
that time the detailed studies of Ulrich have extended the limits
of the order so that it now embraces such families as the Fenestellidex.
and Acanthocladiide, in addition to the Ptilodictyonide and related
families. A concise definition of the order has been given by Ulrich
in the English edition of Zittel’s Textbook of Paleontology. This is
as follows:

Primitive zocecium short, pyriform to oblong, quadrate, or hexagonal, sometimes
tubular, the aperture anterior. In the mature colony the aperture is concealed,
occurring at the bottom of a tubular shaft (“vestibule”), which may be intersected
by straight diaphragms or hemisepta, owing to the direct superimposition of layers
of polypides. Vestibular shaft surrounded by vesicular tissue, or by a solid calcareous
deposit; the external orifice rounded. Marsupia and avicularia wanting.

Comparing the Cryptostomata with the other orders of Bryozoa,
it is found to be most closely related to the Chilostomata; in fact, the
eryptostomatous bryozoans are probably only the Paleozoic repre-
sentatives of the Chilostomata so abundant in Mesozoic, Cenozoic,
and recent times. As pointed out by Ulrich, the Cryptostomata
differ, however, first, in having neither marsupia nor avicularia;
second, in the much greater deposit of calcareous matter upon the
front of the zocecia, thus producing the vestibule; third, in that

EARLY PALEQZOIC BRYOZOA OF THE BALTIC PROVINCES. 113

successive layers of polypides are often developed, one directly over
the other, in a continuous tube; and, fourth, in that whenever a
zoarium attains an uninterrupted width of more than 8 mm., it
exhibits clusters of cells differing more or less, either in size or eleva-
tion, from the average zocecia.

The generic and even specific representation of the Cryptostomata
in the Baltic Ordovician and early Silurian strata is exceptionally
like that in the corresponding beds of America.

Family PTILODICTYONID Zittel.

Zoarium bifoliate, composed of two layers of zocecia, grown together
back to back, usually jointed, at least at the base, and forming leaf-
like expansions or compressed branching or inosculating stems;
mesotheca without median tubuli; zocecia usually have hemisepta
and semielliptical orifices; apertures usually ovate, surrounded either
by a sloping area or a ring-like peristome; vestibules separated by
thick walls.

Genus PTILODICTYA Lonsdale.

Ptilodictya Lonspate, Murchison’s Silurian System, 1839, p. 676.—EicHwaLD,
Lethea Rossica, vol. 1, 1860, p. 387.—Utricu, Journ. Cincinnati Soc.
Nat. Hist., vol: 5, 1882, pp. 151, 162.—Forrstsr, Bull. Sci. Lab. Denison
University, vol. 2, 1887, p. 155 Hat and Smreson, Nat. Hist. New York,
Pal., vol. 6, 1887, p. xix.—Utricn, Geol. Surv. Illinois, vol. 8, 1890, p. 390; —
Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 163; Zittel’s Text-
book of Paleontology (Eng. ed.), 1896, p. 279.—Simpson, Fourteenth Ann.
Rep. State Geologist New York for the year 1894, 1897, p.541.—NicKLEs and
Basstzr, Bull. 173, U. 8. Geol. Surv., 1900, p. 45.—Hennic, Archiv. fur
Zool., K. Sven. Vet.-Akad. Stockholm, vol. 2, No. 10, 1905, p. 16.—Cumines,
Thirty-second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 754.

Escharopora (not Hall, 1847) Hau, Twenty-sixth Ann. Rep. New York State
Mus., 1874, p.99; Thirty-second Ann. Rep. New York State Mus., 1879, p.161.

Heterodictya Nicnouson, Geol. Magazine, new ser., vol. 2, 1875, p. 33; Pal. Prov.
Ontario, 1875, p. 79.—MizzzR, North Amer. Geol. and Pal., 1889, p.309.

Zoarium, a simple, unbranched, lanceolate or falciform frond,
narrow or wide, which articulates with a small basal expansion; in
the young condition the zoarium consists of longitudinally arranged
narrow, oblong-quadrate zocecia, new zocecia of different width and
arrangement being added subsequently on each side; walls of ves-
tibules thick, solid, and with a double row of minute dots.

Genotype.—Flustra lanceolata Lonsdale. Silurian of Europe.

With the Richmond group assigned to the Silurian, the genus
Piilodictya becomes restricted almost entirely to this period, the
single exception being a species in the Lower Devonian of Ontario.
Ptilodictya is closely related to Escharopora and differs most obviously
in the arrangement of its zocecia in parallel longitudinal rows.

114 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

PTILODICTYA FLABELLATA Eichwald.

Text fig. 42.
Ptilodictya flabellata Ercowatp, Lethzea Rossica, vol. 1, 1860, p. 389, pl. 24, figs.
10 a, b.
Cir. Ptilodictya expansa Hati, Twelfth Ann. Rep. Indiana Geol. Nat. Hist., 1883,
pl2s fies! 2.3!

Although this species is briefly described by Hichwald, his figures
are sufficient to show that it is undoubtedly a Ptilodictya closely
related to the typical earliest Silurian forms. A very similar, perhaps
identical American species from the Clinton formation of Ohio, has
been illustrated by Hall as Ptilodictya expansa.

Although specimens of Ptilodictya flabellata have not occurred in
the collections be-
fore me, I have no
hesitancy in includ-
ing it as a valid spe-
cies. Hichwald re-
cords the species as
from the compact
Ordovician (Ortho-
ceratite) limestone,
near Hohenholm,

Fig. 42.—PTMODICTYA FLABELLATA. @, ZOARIUM, NATURAL SIZE, -: l d f D
PARTED ALONG THE MESIAL LAMINA; b, VIEW ENLARGED, SHOWING sian 0 ago,
LONGITUDINAL ARRANGEMENT OF ZO@CIA. ‘(CaLCAIRE compacte A which will place it in
ORTHOCERATITES,’’? ISLAND OF DAGO, NEAR HOHENHOLM. (AFTER

eee ann either the Lyckholm
or Borkholm divi-
sion of formation F. For various reasons, chiefly on account of its
Silurian affinities, and its geographic location, I would regard Ptilo-
dictya flabellata as belonging to the same fauna holding Hallopora
elegantula, Sceptropora facula, Lichenalia concentrica, etc., namely,
that of the Borkholm horizon.
Occurrence.—Hohenholm, island of Dago, probably in the Borkholm
limestone (F2).

PTILODICTYA GLADIOLA Billings.
Text fig. 43.

Ptilodictya gladiola Brt1uines, Cat. Sil. Foss. Anticosti, 1866, p. 10.
Ptilodictya lanceolata KicH wap (not Goldfuss), Lethzea Ross., vol. 1. 1860, p. 388.
An elongated, lamellate, slightly curved bifoliate bryozoan with the
cells arranged in longitudinal rows, has been described by Eichwald
as Ptilodictya lanceolata (Goldfuss), and recorded as from the Ordo-
vician limestone of Lyckholm, as well as from various Silurian
localities. The Ordovician specimens belong, in all probability, to
the form described by Billings as Ptilodictya gladiola, which differs
from typical P. lanceolata mainly in having smaller zoccia. Billings’s

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

115

careful description of P. gladiola applies equally well to the Russian

example before me, and for that reason is quoted:

Polyzoary, consisting of a single elongated, narrow, two-edged,
unbranched frond, usually curved, gradually expanding from an
acute point to a width of about 1 line ina length of from 1 to 28
lines, moderately convex, often subangular along the middle and
with flat slopes to the edges, which are acute. Cells oblong;
when perfect, nearly rectangular at their extremities; when worn,
one or both ends rounded; their length about twice their width,
6 to 8 in the length of 1 line, arranged in very regular longitudinal
rows, of which there are about 12 where the width of the frond is
1line. The largest frond seen is 28 lines in length and 1} in
width at the larger extremity.

Occurrence.—The American type was found in the
earliest Silurian strata equivalent to the Richmond
‘formation, on the island of Anticosti, Gulf of St.
Lawrence. The European specimens believed to
belong to the same species, occur in the Borkholm

Fig. 43.—PTmopDIc-
TYA GLADIOLA.
TANGENTIAL SEC-
TION, X20, SHOW-
ING THE LONGITU-
DINAL ARRANGE-
MENT OF THE ZOG@-

ciIA. BORKHOLM

limestone (F2) at Borkholm and Lyckholm, Esthonia.

Plesiotype.—Cat. No. 57210, U.S.N.M. eee ees!
THONIA.

Genus ESCHAROPORA Hall.

Escharopora Hauu, Nat. Hist. New York, Pal., vol. 1, 1847, p. 72.—Uuricu,
Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 167; Zittel’s
Textbook of Paleontology (Eng. ed.), 1896, p. 279.—NicKiEs and BassteEr,
Bull. 173, U. 8. Geol. Surv., 1900, p. 45.—Cumines, Thirty-second Ann.
Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 745.

Ptilodictya (part), various authors.

Although long considered a synonym of Ptilodictya, the species of
Escharopora form a natural assemblage related to the former genus
in its general zoarial and zocecial characters but differing mainly in
the arrangements of their apertures. In Péilodictya the zoccial aper-
tures are arranged in regular longitudinal rows; in Escharopora their
arrangement is in diagonally intersecting series. The internal struc-
ture of the two genera is essentially the same.

All of the species of Hscharopora are of Ordovician age while the
oldest known forms of Ptilodictya occur in the earliest Silurian (Rich-
mond) deposits. The close relationship between the two genera is
thus apparent from their geologic distribution, Ptilodictya being
undoubtedly a derivative of the earlier genus.

Genotype.—Escharopora recta Hall. Middle Ordovician of New
York and Canada.

116 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.
ESCHAROPORA SUBRECTA (Ulrich).

Text fig. 44.

Ptilodictya subrecta Utricn, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 63; Geol. and Nat. Hist Surv. Minnesota, vol. 3, pt. 1,
1893, p. 168, pl. 12, figs. 5-29.

Cir. Micropora hamte EicHwatp, Letheea Rossica, vol. 1, 1860, p. 395.

The only species of Escharopora recognized in the Baltic strata is
represented by a number of well preserved examples from the Wassa-
lem beds (D3) at Uxnorm. These agree in all their characters and
show the same range of variation as the abundant American form
E. subrecta, the types of which are before me for comparison. Ulrich
has given a very detailed and careful description of the species and
has illustrated it most fully in his third volume of the Minnesota
reports. Certain of his figures are exactly duplicated in the Rus-
sian specimens, and these have been selected for illustrating the
species at the present time.

The zoarium is usually a simple, smooth, bifoliate expansion with
the lower portion gradually tapering to a pointed, articulating, finely
striated basal extremity, as shown in figures 44a and 6. Older speci-
mens may reach the size shown in figures 44 d and ¢, and, as in the
latter, somewhat inconspicuous monticules may be developed. The
finely striated basal portion is composed of elongated groove-like
spaces which become wider further up in the zoarium and gradually
change into the elongate confluent zoccial aperture characteristic
of the species. This change is illustrated in figure 44 6, and the
usual aspect and arrangement of the aperture is shown in figure 44 c.

Measuring lengthwise there are about 11 apertures in 5 mm. and
diagonally 9 to 10 in half that distance. Six of the central rows
occur in 1 mm., measuring transversely. As indicated in several of
the figures, the walls frequently fail to join and thus leave narrow
channels between the apertures. In old examples, such as shown in
figure 44 e, these channels are sometimes replaced by mesopores (fig.
44 f), giving a less regular arrangement to the zoccia.

The two sections reproduced in figures 44 g and h exhibit the
internal structure clearly enough to make its detailed description
unnecessary. However, the long, primitive cell in tangential section
and the slight development of hemisepta as shown in the vertical, are
to be noted.

The simple, pointed, bifoliate zoarium and the elongate, somewhat
confluent, diagonally arranged zoccia of Escharopora subrecta are so
unlike any associated Russian forms that comparisons are hardly
needed. The pointed base is usually preserved and this alone gives
a good clue to the species. Other bifoliate species with pointed
bases, such as Graptodictya proava have a quite different zoarium.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 117

In all probability Eichwald has described this same species under
the name of ificropora rhombica, but his figures and description are
of little value for accurate identification.

Occurrence.—In America Escharopora subrecta is a common fossil

Fiq. 44.—ESCHAROPORA SUBRECTA. @ AND 6b, A TYPICAL SPECIMEN, NATURAL SIZE AND THE BASAL PORTION
OF THE SAME, X9; ¢c, VIEW OF THE CENTRAL PART OF THE SAME ZOARIUM, X9; d AND €, TWO SPECIMENS,
NATURAL SIZE, BROADER THAN USUAL, THE LATTER EXHIBITING A ROW OF MONTICULES; f, SURFACE OF
THE LOWER PART OF ANOTHER EXAMPLE, X18, SHOWING UNUSUAL CONDITIONS; g, TANGENTIAL SECTION,
X18, CUTTING THE IMMATURE AND MATURE PARTS OF THE ZOARIUM; h, PORTION OF A VERTICAL SECTION,
X18. BLAck RIVER (DECORAH) SHALES, ST. PAUL AND MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

in the lower beds of the Black River (Decorah) shales of Minnesota
and Iowa. In Europe it is known only from the Wassalem beds
(D3) at Uxnorm, where specimens are equally abundant. (Cat. No.
57211, U.S.N.M.)

British Museum, specimen and thin section from the Wassalem
beds, at Uxnorm.

118 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Genus PHA NOPORA Hall.

Phznopora Hatt, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 379; Nat. Hist.
New York, Pal., vol. 2, 1852, p.46.—Picrrt, Traite de Paleontologie, 2d. ed.,
vol. 4, 1857, p. 169.—Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5,
1882, p. 152.—Forrste, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 157.—
Muuer, North Amer. Geol. and Pal., 1889, p. 314——Utricu, Geol. Surv.
Tllinois, vol. 8, 1890, p. 392; Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 173.—Poora, Syst. Sil. Center Boheme, vol. 8, pt. 1, 1894,
p. 8.—Utricu, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 279.—
Simpson, Fourteenth Ann. Rep. State Geologist New York for the Year 1894,
1897, p. 541.—Nicxxes and Basser, Bull. 1738, U. 8. Geol. Surv., 1900, p.
46.—Hennic, Archiv. fur Zool., K. Sven. Vet.-Akad. Stockholm, vol. 2,
No. 10, 1905, p. 10.—BasstER, Bull. 292, U. 8. Geol. Surv., 1906, p. 55.

Like Ptilodictya and Escharopora, except that there are two meso-
pores in each interspace between the ends of the apertures.
Genotype.—Phenopora explanata Hall. Silurian (Clinton) of
Canada.
PHANOPORA ENSIFORMIS Hall.
Text fig. 45.

Phznopora ensiformis Haut, Nat. Hist. New York, Pal., vol. 2, 1852, p. 48, pl. 18,
figs. 8 a-c.—NicHotson and Hrinpx, Canadian Journal, new ser., vol. 14,
1874, p. 142.—NicHotson, Pal. Province Ontario, 1875, p. 45, figs. 19, 2,
2a.—Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 172.—
Forrste, Geol. Surv. Ohio, vol. 7, 1895, p. 598.—Bassuer, Bull. 292, U.S.
Geol. Surv., 1906, p. 55, pl. 27, figs. 8, 9.
Phenopora cf. ensiformis Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2,
1902, p. 180, pl. 6, figs. 25-28.

Specimens of this species have not occurred in the collections
before me, but I have no reason to doubt that Wiman’s provisional
identification can be accepted as correct. His figures certainly refer

a

Fig. 45.—PH@NOPORA ENSIFORMIS. WIMAN’S ILLUSTRATIONS OF THE BORKHOLM FORM OF THIS SPECIES;
@ AND b, TWO SMALL ZOARIA, NATURAL SIZE; Cc, SURFACE, X10; d, TRANSVERSE SECTION, X10. BOoRK-
HOLM DRIFT, OJLE MYR, ISLAND OF GOTHLAND.

to a form like Phenopora ensiformis in which the two mesopores at
the end of the zoccia are poorly developed. The occurrence of other
early Silurian types, such as Hallopora elegantula and Inchenalia con-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 119

centrica in the Borkholm limestone, is also indicative of the fact that
the presence of Phenopora ensiformis would not be unexpected.

The zoarium is a narrow bifoliate expansion pointed at the base
for articulation and averaging 25 mm. in length and 2 mm. in width;
each face bears from seven to eleven parallel rows of zocecia with six
zocecia in 2 mm. measuring longitudinally; the apertures are ar-
ranged in linear series between slightly raised longitudinal lines,
are quadrangular in shape, and measure about 0.18 by 0.30 mm.
In the marginal series they are oval, slightly oblique, and somewhat
larger than in the middle rows. The characteristic two mesopores
occupying the inner spaces between the ends of the apertures are
often discerned with difficulty, but upon close examination or by
use of thin sections the mesopores may be found in the position
normal for Phzenopora.

Occurrence.—Abundant in the Clinton rocks of western New York
and Ontario and not uncommon in the Rochester shale of the same
region. Rare in the Clinton rocks of Ohio and also in the Osgood
beds at Osgood, Indiana. Wiman obtained the species from drift
bowlders of the Borkholm formation (F2) at Ojle Myr, island of
Gothland.

Specimens from American localities are in the collections of the
United States National Museum and the British Museum.

Genus ARTHROPORA Ulrich.

Arthropora Uxricu, Journ Cincinnati Soc. Nat. Hist., vol. 5, 1882, pp. 152, 167.—
MitueR, North Amer. Geol. and Pal., 1889, p. 293.—Uuricu, Geol. Surv.
Illinois, vol. 8, 1890, p. 393; Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1898, p. 176.—Pocra, Syst. Sil. Center Boheme, vol. 8, pt. 2, 1894,
p. 14.—Utricu, Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 279.—
Srupson, Fourteenth Ann. Rep. State Geologist of New York for the Year
1894, 1897, p. 605.—NickiES and BassueR, Bull. 173, U. 8. Geol. Surv.,
1900, p. 46.—Cumines, Thirty-second Ann. Rep. Dep. Geol. Nat. Res.
Indiana, 1907, p. 739.

Zoarium bushy, composed of numerous articulating equal seg-
ments, spread in a plane; apertures elliptical, surrounded by a deli-
cate peristome; interspaces with one or more thread-like ridges
variously disposed and with a row of minute papille.

Genotype—Stictopora (Piilodictya) shafferi Meek. Upper Ordovi-
cian (Maysville) of the Ohio Valley.

The members of this interesting genus are readily distinguished
from all other species of the family by their segmented character.
Although complete zoaria are rare, their disjointed segments are
readily identified by the rounded and pointed ends adapted for
articulation. The genus is rather numerously represented in Amer-
ican Ordovician strata, but in Russia only a single species has been
noted.

120 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

ARTHROPORA SIMPLEX Ulrich.
Text fig. 46.

Arthropora simplex Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Min-
nesota, 1886, p. 65; Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
177, pl. 14, figs. 12-21.

The identification of this neat little species in Russian strata is
based in part upon a small single specimen from Uxnorm, which
does not present all of the specific and generic characters because
the important pointed base for articulation with the preceding seg-
ment is broken away. That the species is undoubtedly present in

Fic. 46.—ARTHROPORA SIMPLEX. @,SEVERALSEGMENTS IN THEIR NATURAL POSITION, LIFE SIZE; 6, SURFACE
OF A WELL-PRESERVED FRAGMENT, X18; c, SEVERAL ZOGCIAL APERTURES OF THE SAME, X35; d, TANGEN-
TIAL SECTION, X18, SHOWING STRUCTURE OF THE DIFFERENT PARTS OF THE ZOARIUM; ¢€, VERTICAL SECTION,
18, ILLUSTRATING FORM OF ZOGCIA AND HEMISEPTA. BLACK RIVER (DECORAH) SHALE, MINNEAPOLIS,
MINNESOTA. (AFTER ULRICH.)

the Wassalem beds seems most certain from thin sections of speci-
mens accidentally encountered in the interior of limestone fragments
which were being studied for other species. To assist in the identi-
fication of the species a few of Ulrich’s figures are introduced and
the following abridged description is inserted:

Zoarium jointed, consisting of narrow, bifoliate, unbranched
stems, rounded and solid at the ends for articulation; averaging 18
mm. in length, 1.5 mm. in width, and less than 1 mm. in thickness.
Zocecial apertures elliptical and surrounded by a thin, granose peri-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 121

stome, which is elevated and prolonged at each end. The surface is
also ornamented by a thin, papillose, wavy ridge separating the
longitudinal rows of zowecia. The simple, unbranched segments of
this species with their ends rounded for articulation with each other
will distinguish them from all other associated bryozoans.
Oecurrence—An abundant fossil in the lower half of the Black
River (Decorah) shales, in Minnesota and Iowa; apparently rare in
the Wassalem beds (D3) at Uxnorm. (Cat. No. 57212, U.S.N.M.).
American specimens are in the collections of the British Museum.

Genus GRAPTODICTYA Ulrich.

Graptodictya Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, pp. 151,
165.—MiiteR, North Amer. Geol. and Pal., 1889, p. 307.—Uzricu, Geol.
Surv. Illinois, vol. 8, 1890, p. 393.—Pocta, Syst. Sil. Center Boheme, vol. 8,
pt. 1, 1894, p. 14.—Smirson, Fourteenth Ann. Rep. New York State Geolo-
gist for the Year 1894, 1897, p. 541.—Nicxues and Bassier, Bull. 173, U. 8.
Geol. Surv., 1900, p. 46.—Cumrines, Thirty-second Ann. Rep. Dep. Geol.
Nat. Res. Indiana, 1907, p. 747.

This genus may be considered as an Arthropora with the jointed
character of the zoarium limited to the base alone. The zoccial
structure and surface ornament are alike in both genera, but the
rather large, single, narrow branching frond of Graptodictya with a
pointed, striated base articulating with a small basal expansion is

Fig. 47.—GRAPTODICTYA PERELEGANS. da, TANGENTIAL SECTION, X20, OF THE TYPE-SPECIMEN; 6, SEVERAL
ZO@CIA, X40; c, VERTICAL SECTION, X20; d, TRANSVERSE SECTION, X20. RICHMOND GROUP, CLARKS-
VILLE, OHIO.

quite different from the numerously segmented method of growth in
Arthropora.

The Russian specimens referred to the genus include a species very
similar in growth and other features to the American genotype, and
in addition two cribrose forms—a method of growth which hitherto
had not been recognized in the genus. The method of growth in the
two latter species Graptodictya proava (Kichwald) and G. obliqua,

<

122 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

new species, is exactly the same as in Clathropora, where many
students would probably refer both of them. However, in the latter
genus the zoecial structure is exactly the same as in Ptilodictya,
from which Clathropora is distinguished only by its cribrose or clathrate
zoarilum. Granting that this is a sufficient generic distinction,
new genera would be necessary for the clathrate species of Grapto-
dictya and of Stictoporella, but I am unwilling to believe at present
that such genera would be of any advantage. The zoccia of both
Graptodictya and Arthropora differ from those of Ptilodictya in having
low peristomes and in being separated from each other by solid
interspaces bearing one or more tortuous, fine, elevated lines.

Although Graptodictya has been defined by Ulrich and compared
with related genera on several occasions, no illustrations of the inter-
nal structure of the type species have ever been published. On account
of the close relationship between Graptodictya perelegans, the geno-
type, and the new species G. bonnemai, I am taking this opportunity
to present the accompanying views of the former (fig. 47) to illustrate
the generic structure, as well as for comparison with the latter species.

Genotype.—Graptodictya perelegans (Ulrich). Earliest Silurian
(Richmond) of the Ohio Valley.

GRAPTODICTYA BONNEMAI, new species.
Plate 8, fig. 3; text fig. 48.

Cir. Graptodictya (Ptilodictya) perelegans (UtricH), Journ. Cincinnati Soc. Nat.
Hist., vol. 1, 1878, p. 94, pl. 4, figs. 16, 16a.

The close relationship existing between this new species and the
genotype has been noted under the generic remarks. The internal
structure of the two is practically identical, and, were it not for cer-
tain differences in method of growth, they could hardly be distin-
guished specifically. As it is, Graptodictya bonnemai is most certainly
the forerunner of G. perelegans, and the occurrence of such similar
species in the Middle Ordovician and earliest Silurian strata is but
another instance of the close relationship between the faunas of these
two periods.

Critically compared, the zoarium of G. bonnemai is found to branch
much less frequently than its later representative. Each species
branches dichotomously at regular intervals; in G. perelegans this
branching occurs at intervals averaging 4 mm.; in the present form
10 mm. is the usual distance between the bifurcations. This gives a
more delicate aspect to the Russian form. Other differences may be
noticed in the shape of the apertures, which in G. bonnemaz are, as a
rule, more elongate, but this is a character which varies with age
and must therefore be used with caution.

The dichotomously branching, slender, ribbon-like zoarium of G.
bonnemat with its long, narrow base, pointed for articulation, and

EARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 123

the beautiful surface character of the zoccia, forms one of the pret-
tiest species in the Baltic Ordovician. The specific name is in honor
of Dr. J. H. Bonnema, of The Hague, Holland, in appreciation of his
excellent work upon the Ostracoda of the Kuckers formation.
Occurrence-—A common fossil in the Kuckers shale (C2), Baron
Toll’s estate, Esthonia. Specimens referred to the species occur also

Fic. 48.—GRAPTODICTYA BONNEMAI. @, PORTION OF A ZOARIUM, NATURAL SIZE, SHOWING THE POINTED
BASE AND FREQUENCY OF BRANCHING; b, TANGENTIAL SECTION, X20, CUTTING BOTH MATURE AND IMMA-
TURE REGIONS; c AND d, SEVERAL ZOGCIA OF THE SAME, X40, WITH ONE STILL FURTHER ENLARGED,
X60; €, VERTICAL SECTION, X20, ILLUSTRATING THE PROMINENT SUPERIOR HEMISEPTUM. KUCKERS
SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

in the Jewe limestone (D1), Baron Toll’s estate, and in the Wesen-
berg limestone (EZ) at Wesenberg, Esthonia.
Cotypes.—Cat. No. 57213, U.S.N.M.

Specimens from the Kuckers shale (C2), Baron Toll’s estate, are in
the collections of the British Museum.

GRAPTODICTYA PROAVA (Eichwald).
Plate 8, fig. 2; plate 9, figs. 1-6; text figs. 49, 50.

Gorgonia proavus ErcHwaLD, Urwelt Russlands, vol. 2, p. 44, pl. 1, fig. 5.

Coscintum proavus Eicowatp, Lethzea Rossica, vol. 1, 1860, p. 398.

Stictoporella cribrosa SARDESON (not Ulrich), Journ. Geol., vol. 9, 1901, p. 157,
pl. B, figs. 7-9.

Clathropora flabellata Hatt, Foster and Whitney’s Rep. Geol. Lake Superior Land
District, pt. 2, 1851, p. 207, pl. 24, figs. 2a, b.

Stictoporella flabellata NicktEs and BasstEr, Bull. 173, U. 8. Geol. Surv., 1900,
p. 416.

?Coscinium proavium Brrtunes, Geol. Canada, Geol. Surv. Canada, 1863, p. 158,
fig. 122.

This splendid species, with its large, cribrose zoarium and con-
spicuously striated, pointed base, furnishes probably the most showy
cabinet specimen of any of the Russian bryozoans. Fragments are
abundant in the Wassalem beds (D3) at several localities in Esthonia,

92602°—Bull. 77—11——10

124 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

and more complete specimens preserving the pointed base are by no
means rare. Although Eichwald gives but a single illustration of the
species, a view, natural size, of a zoarium preserving the pointed base
(fig. 49 a), there can be little question that his type of Cosemvum
proavus and the specimen figured in the present work are identical,
mainly because Graptodictya proava is the only known cribrose Mid-
dle Ordovician Russian bryozoan with the pointed base and dimen-
sions shown in his figure. This same species has been found in
American strata, as determined from my study of the specimen (See
fig. 6, pl. 9) which Sardeson, in his ‘‘Problem of the Monticuli-
poroidea’’! figures and describes at length under the name of Stic-
toporella cribrosa Ulrich. In spite of Sardeson’s statement to the
contrary, it is a fact that species of Stictoporella have an expanded
incrusting base and never have a pointed base for articulation. Com-
parison of figures of
both species here pre-
sented can not fail to
convince the discrimi-
nating person of numer-
ous zoarial and zocecial
differences between
Stictoporella cribrosa
Ulrich and Graptodictya
proava. Indeed, ob-

servers who have had
Fig. 49.—GRAPTODICTYA PROAVA. @, EICHWALD’S VIEW OF THE opportunity to study
TYPE-SPECIMEN OF HIS COSCINIUM PROAVUM, NATURAL SIZE,
SHOWING THE CRIBROSE ZOARIUM AND THE cHaRAcTERIsSTIC NUMETOUS examples of
STRIATED, POINTED BASE. ‘‘CALCAIRE A ORTHOCERATITES,’’ NEAR these several t es of
REVAL, ESTHONIA; 0, TANGENTIAL SECTION OF HALL’S TYPE OF , ye
CLATHROPORA FLABELLATA, X30, INTRODUCED FOR COMPARISON. structure, assign them
LOWEsT TRENTON, ESCANABA RIVER, MICHIGAN. to separate families, as
in the present work. Graptodictya proava is known from a second
American locality, namely, along the Escanaba River in Michigan,
below the upper falls. A fine, large example from this place was
made the type of Hall’s Clathropora flabellata. Through the courtesy
of Dr. E. O. Hovey, of the American Museum of Natural History, I
have had the opportunity of studying this type and of presenting

an illustration of its minute structure to show the specific identity.

The specimen itself has been broken out of the solid limestone and —

thus is parted along the mesial lamina. Its cribrose zoarium has
the same dimensions seen in the large examples of G. proava, and it
clearly arises from a pointed base, although a portion of this is
broken away.

The cribrose, bifoliate bryozoan, figured by Billings as Cosconvum
proavus Kichwald, may be correctly identified, but in the absence of

1journ. Geol., vol. 9, 1901, p. 150.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 125

the illustrated specimen, which appears to be lost, the matter can
not be settled. As the basal portion is not shown, the specimen may
be a cribrose Stictoporella.

Description.—Zoarium of narrow, bifoliate branches averaging
2.5 mm. in width, inosculating so frequently that a broad frond, with
circular or elliptical openings, results. The lower portion of the
cribrose zoarium is prolonged into a striated base which is long, nar-
row, and pointed in young examples (see fig. 2, pl. 9), and short and
more or less rounded in older specimens (see figs. 1, 3, 6, pl. 9).
This base articulates with an expanded attachment, as shown in

figure 5, plate 9. An average zoarium is 50 mm. in its longer

diameter, but larger specimens frequently occur.
Fenestrules sometimes circular but generally elliptical, and aver-
aging 1.5 by 1.8mm. Although their size and arrangement is more

Fig.50.—GRAPTODICTYA PROAVA. @, TANGENTIAL SECTION, X20, CUTTING THE STRIATED EDGE OF A BRANCH
AND THE ADJOINING ZOGCIA; b, PORTION OF THE SAME, X40; c, VERTICAL SECTION, X20. WASSALEM
BEDS (D3), UXNORM, ESTHONIA.

or less irregular, large examples, such as illustrated on plate 9,
figure 1, show them disposed in irregular, diagonal, intersecting rows.

Zoccia subpolygonal, sometimes subrhomboidal in outline with
elliptical to circular apertures. Interspaces solid with one or two
fine, elevated, papillose limes. Mesopores restricted almost entirely
to the edges of the branches, where they form a band around the
fenestrules about 0.5 mm. wide. In the lower portion of old zoaria,
the fenestrules are often obliterated by the greatly increased width
of this band of mesopores. Occasionally a small mesopore or two
may be noted among the ordinary zoewcia. The articulating pointed
base is composed of elongate, narrow, modified zoccia separated
by wide, solid interspaces with numerous elevated lines, this com-
bination of elongate zocecia and intervening lines producing the
striated appearance. The attached socketlike basal expansion is

126 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

made up of similarly modified zoecia and broad interspaces. In
all cases, the elevated lines traversing the interspaces are minutely
papillose. Views of the internal structure are given in figure 50.
Occurrence.—Kichwald mentions two localities for his species, first,
the ‘‘calcaire & Orthoceratites” at Reval, and, second, the dolomite
[Lyckholm-Borkholm formation] at Borkholm. The numerous
examples coming from the Wassalem beds (D3) at Uxnorm, in the
vicinity of Reval, identical with his figured specimen, cause me to
believe that the latter was derived from the same place. Eichwald’s
Borkholm specimens probably belong to the species next described

as Graptodictya obliqua. The American occurrences are (1) in the.

Clitambonites bed of the lower Trenton limestone, near Kenyon,
Minnesota, and (2) in the lowest Trenton or late Black River limes-
tone, along the Escanaba River, Michigan, below the falls.
Plesiotypes.—Cat. No. 57216, U.S.N.M.
Specimens and thin sections from the Wassalem beds at Uxnorm,
Esthonia, are in the collections of the British Museum.

GRAPTODICTYA OBLIQUA,‘new species.
Plate 8, fig. 4; text fig. 51.

Compared with other cribrose species, this new form differs so
decidedly in zocecial structure that it need be discriminated only
from the abundant Graptodictya proava (Hichwald), of the Wassalem
beds. Careful comparison shows the following differences: First,

7)

Fic. 51.—GRAPTODICTYA OBLIQUA. @, THE TYPE-SPECIMEN, NATURAL SIZE, SHOWING THE STRIATED BASAL
PORTION; 6, TANGENTIAL SECTION, X20, EXHIBITING THE WIDE, INTERZOGCIAL SPACES; C, VERTICAL
SECTION, X20, WITH THE INTERZOGCIAL SPACES FILLED BY LAMINATED TISSUE. LOWER PART OF LYCK-
HOLM “LIMESTONE (F1), KERTEL, ISLAND OF DAGO, ESTHONIA.

the zoarium of @. obliqua is much coarser, its fenestrules being twice
the size of those in G. proava. Its zoccia also are larger, with four
in 2 mm., and are directed obliquely to the growing edge; the orna-
mentation of the surface is likewise coarser. Altogether G. obliqua

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 127

is larger and coarser in every respect than any other species of the
genus. Its internal structure, however, is quite similar to that of
typical Graptodictya, so that there can be little question of its generic
placement.

The type-specimen shown in figure 51 a lacks the characteristic
basal articulating point, but this undoubtedly was present and has
only been lost.

Occurrence.—Apparently rare in the lower part of the Lyckholm
limestone (F1) at Kurkiill, Esthonia.

Holotype-—Cat. No. 57220, U.S.N.M.

British Museum, thin section of type-specimen.

7 Family STICTOPORELLIDZ Nickles and Bassler.

This family differs from the Ptilodictyonide mainly in that the
zoarium is not articulated, but grows upward from, and is continuous
with, a spreading base.

Of the seven genera referred to the Stictoporellide, only the type
genus Stictoporella is known at present in the lower Paleozoic rocks
of Russia.

Genusront (CLO PORER MEA Ulrich:

Stictoporella Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, pp. 152,
169; Geol. Surv. Illinois, vol. 8, 1890, p. 394; Geol. and Nat. Hist. Surv.
Minnesota, vol. 3, pt. 1, 1898, p. 179; Zittel’s Textbook of Paleontology
(Eng. ed.), 1896, p. 279.—Simpson, Fourteenth Ann. Rep. State Geologist
New York for the year 1894, 1897, p. 535.—NicxzizEs and Basser, Bull. 173,
U. 8. Geol. Surv., 1900, p. 46.—Cumines, Thirty-second Ann. Rep. Dep.
Geol. Nat. Res. Indiana, 1907, p. 756.

Micropora Etcuwaup, Bull. Soc. Nat. Moscou, No. 4, 1855, p. 457; Lethea
Rossica, vol. 1, 1860, p. 393.

Not Micropora Gray, List of the specimens of British animals in the collection
of the British Museum, pt. 1, Centroniz or Radiated Animals, 1848, pp.
115, 147.

Zoarium branching, cribrose, or leaflike; zocecia with the primi-
tive portion tubular, usually long, generally without hemisepta, the
inferior one only occasionally present; orifices at the bottom of a
wide, sloping vestibule; thick-walled, untabulated mesopores occur
between the apertures and line the margins of the zoarium.

Genotype.—Stictoporella «interstincta Ulrich= Pitlodictya flemuosa
James. Upper Ordovician (Eden) of the Ohio Valley.

The diagnostic features of this genus, aside from its family char-
acters, are the long tubular primitive portion of the zocecium and
the presence of more or less numerous, untabulated, thick-walled
mesopores. Eichwald founded his new genus Micropora upon a
species which proves upon further investigation to be a Stictoporella.
However, the name Micropora was preoccupied by Gray for a genus
of chilostomatous bryozoans, so that Stictoporella remains a valid
name.

128 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

STICTOPORELLA CRIBROSA Ulrich.
Plate 7, fig. 4; text figs. 52, 53.

Stictoporella? cribrosa Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 69.

Stictoporella cribrosa Uuricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 184, pl. 10, figs. 21-25; pl. 11, figs. 22, 23.—Smmeson, Fourteenth
Ann. Rep. State Geologist New York for the year 1894, 1897, p. 536, fig. 93.

Zoarium composed of narrow, bifoliate, smooth branches, aver-
aging 2.5 mm. in breadth, inosculating so frequently that a broad
expansion perforated by rounded or elliptical fenestrules at rather
irregular intervals is the result. Specimens preserving the basal

Fic. 52.—STICTOPORELLA CRIBROSA. @, NEARLY COMPLETE ZOARIUM NATURAL SIZE; 0 AND C, SURFACE OF
A SPECIMEN WITH NUMEROUS MESOPORES, X9 AND A PORTION X18; d, VERTICAL SECTION, X18; e€, TAN-
GENTIAL SECTION OF AN AVERAGE SPECIMEN, X18. BLACK RIVER (DECORAH) SHALES, MINNEAPOLIS
MINNESOTA. (AFTER ULRICH.)

portion are not common, but show clearly that the zoarial growth
is from a small incrusting basal expansion into thin, erect fronds.
The largest of the Russian specimens, although still incomplete, is
over 70 mm. in its longer diameter. Fronds celluliferous on both
sides, as usual in such bifoliate specimens. Fenestrules about 2 mm.
in their greatest diameter, although a variation of 1 mm. in each
direction from this figure may be observed. This irregularity of
the fenestrules is matched by a corresponding variation in the width
of the branches, which range from 1.5 mm. to 3 mm., in round
numbers. Zocecial apertures small when compared with other
bryozoans, but large for this particular section of the genus, subcir-
cular and set in well-defined, polygonal, sloping areas. The usual

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 129

aperture is about 0.10 mm. by 0.12 mm., and seven to eight may be
counted in 2 mm.; when well preserved, many of the apertures are
closed by a convex subcentrally perforated plate. Mesopores
small and sometimes few, but often numerous enough to isolate the
zoccia. Along the edges of the zoarial branches around the fenes-
trules, there is a band of mesopores 0.5 mm. or more in width.

The internal features illustrated in figure 53, prepared from a Rus-
sian example, differ from typical species of Stictoporella cribrosa only
in the scarcity of mesopores and the corresponding greater size of the
zocecia. In tangential sections the polygonal areas are plainly
marked out, and the cavity of the zocecium is seen to be subcircular or
ovate and of less diameter than the walls. The mesopores vary in
size and shape and are sometimes completely filled by deposits of
sclerenchyma.

An examination of numerous specimens from both the American
and Russian localities shows that the zocecium has some variation in
size. This is due, as in
other bryozoans, to the
number of mesopores
present. When meso-
pores are few, the zoccia
are larger, but with nu-
merous mesopores the
zocecia become decreased
insize. In each case the

ib f ° . Fic. 53.—STICTOPORELLA CRIBROSA. @ AND Db, TANGENTIAL AND
numper o Zoccla IM a VERTICAL SECTIONS, 24, OF A WELL DEVELOPED RUSSIAN
given space is the same. EXAMPLE IN WHICH MESOPORES ARE LESS ABUNDANT THAN

Wlich’s usteations ( fie. USUAL. WASSALEM BEDS (D3), UXNORM, ESTHONIA.
52) show the condition in which mesopores are most numerous, while
the thin section shown in figure 53 illustrates the opposite condition.

The occurrence of such highly organized and well-marked species
as Graptodictya proava (Kichwald) and Stictoporella cribrosa Ulrich
in both the American and Russian strata without a single variation
in their respective specific characters was one of the pleasant surprises
of my studies, and to me, at least, was good evidence of the great
stratigraphic value of these organisms. Moreover, these species
offer so many characters for discrimination that their identification
can be made with utmost certainty.

The associated species, Graptodictya proava (Eichwald), has a similar
cribrose zoarium, but differs in its striated base pointed for articu-
lation. When this base is not present, the absence of mesopores and
the smaller, differently shaped zoecia of the Graptodictya are suffi-
cient to distinguish it. Stictoporella gracilis (Kichwald) is also a
cribrose species, but, as indicated under its description, the dimen-
sions of its zoarium and the shape of the zoccia are quite different.

130 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Coscinium prenuntium, new species, likewise has a’ cribrose
zoarium and an attached base, but the zocecia are rounded and pro-
vided with a distinct lunarium. Internally the latter species is, of
course, quite different.

Occurrence.—Ulrich’s types are from the Rhinidictya bed of the
Black River (Decorah) shales, at Minneapolis and St. Paul, Minnesota,
but the species is abundant in this as well as the Stictoporella and
Ctenodonta beds of the same formation. In Russia specimens are
numerous in the Wassalem beds (D3) at Uxnorm and Gut Sack, in
Esthonia.

Plesiotype—Cat. No. 57221, U.S.N.M.

Specimens and thin sections from the Wassalem beds at Uxnorm
are in the collections of the British Museum.

STICTOPORELLA GRACILIS (Eichwald).
Plate 7, figs. 1-3; text figs. 54, 55.

Eschara gracilis Ercuwaup, Schichtensyst. v. Esthland, 1840, p. 205; Urwelt von
Russland, pt. 2, p. 48, pl. 1, fig. 4.
Micropora gracilis Ercawap, Lethea Rossica,vol. 1, 1860, p. 393, pl. 33, fig. 4a, 6.
The first illustration of this species, published by Eichwald, is
hardly sufficient for its accurate identification, but the figures given
in his Lethzea Rossica refer undoubtedly to the cribrose bryozoan here
referred to the genus Stictoporella. This species is represented in the
collections before me by fragmentary examples from a number of
localities in the
government of St.
Petersburg, all of
them coming from
the Glauconite
limestone. The
most perfect of

these examples is
Fig. 54.—STICTOPORELLA GRACILIS. @, EICHWALD’S ORIGINAL FIGURE (ES- shown on plate i
CHARA GRACILIS); 6 AND € COPIES OF EICHWALD’S ILLUSTRATIONS OF
MICROPORA GRACILIS; 0, A ZOARIUM, NATURAL SIZE, AND C, SURFACE OF figure ils where the
SAME, ENLARGED. ‘‘CALCAIRE A ORTHOCERATITES,’’ ISWOSS, GOVERN- zoarium is seen
MENT OF ST. PETERSBURG.

to be of cribrose

branches averaging 4 mm.in width and arising from an expanded

base. As usual in such forms of growth, the basal expansion and the
initial branches are finely striated instead of celluliferous.

The zocecial apertures are rather large for the genus, with four in

2 mm., oval, and more or less oblique, with five to seven rows in the

width of a branch. The apertures are separated by longitudinal

ridges, while shallow depressions or mesopores occupy the spaces at

the distal end of the zowcia. As shown in figure 3 of plate 7, the mar-

gins of the branches are made up of the same finely striated, porous

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 131

tissue found ‘at the base of the zoartum. The internal structure of
the species is shown in figure 55, where the oval zoewcia separated by
ridges and occasional mesopore-like spaces of the tangential section,
and the long, tubular, primitive zocecium of the vertical section are
the most noteworthy features.

There is no known
Russian species with
which Stictoporella gra-
cilisneed be compared.
In America its closest
ally seems to be Sticto-
porella exigua Ulrich,
from the lowest beds
of the Trenton lime-
stone at Montreal,
Canada. The latter
has a quite similar
zocecial structure, but Fic. 55.—STICTOPORELLA GRACILIS. @, TANGENTIAL SECTION, X20;
is very different in 8, verticaL section, X20. GLAUCONITE LIMESTONE (B2), WAs-
zoarial grow th. 4 SILKOWA, GOVERNMENT OF ST. PETERSBURG.

Occurrence—Common in the Glauconite limestone (B2) at Wassil-
kowa, on the Lawa, Oberchowo and Tswos, on the Wolchow, and
Gornaja Scheldicha, on Lake Ladoga, government of St. Petersburg.

Plesiotypes—Cat. No. 57223, U.S.N.M.

British Museum, specimens and thin sections from the Glauconite
limestone at Wassilkowa.

Family RHINIDICTYONID Ulrich.

This prolific family is almost restricted to the Ordovician and
includes genera which, in the general shape of the zoarium, seem to
be little different from the various preceding Cryptostomata. The
zocecial structure, however, is distinctly different, the most obvious
points of difference bemg the presence of median tubuli between the
median lamine, and between the longitudinal rows of zoecial tubes.
Mesopores are absent, but the interzocecial spaces are often filled
with vesicles.

Genus RHINIDICTYA Ulrich.

Rhinidictya Utrics, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 152.—
Hatt and Smupeson, Nat. Hist. New York, Pal., vol. 6, 1887, p. xx.—Utricu,
Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 124; Zittel’s
Textbook of Paleontology (Eng. ed.), 1896, p. 279.—Stmpson, Fourteenth
Ann. Rep. State Geol. New York for the year 1894, 1897, p. 605.—NicKLES
and BassterR, Bull. 173, U. S. Geol. Surv., 1900, p. 48.—Cumines, Thirty-
second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 755.

Stictopora (part) Haiti, Nat. Hist. New York, Pal., vol. 1, 1847, p. 73.

Stictopora (not Hall) Unricu, Geol. Surv. Illinois, vol. 8, 1890, p. 388.

This fine genus is represented in the Russian deposits by two well-
marked forms, one from the Wassalem beds, which can not be dis-

132 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

tinguished from the common Minnesota species Rhinidictya mutabilis,
and a second closely related species from the Wesenberg limestone,
differmg mainly in having much larger zocecia. In America the genus
has a rather prolific representation both in species and in specimens.
While specimens are not infrequent in the Russian strata mentioned
above, the scanty specific development is rather unusual.

Genotype.—Rhimdictya nicholson Ulrich. Middle Ordovician of
the United States and Canada.

RHINIDICTYA MUTABILIS (Ulrich).
Text fig. 56.

Stictopora mutabilis (part) Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 66. :
Stictopora mutabilis MILLER, North Amer. Geol. and Pal., 1889, p. 324, fig. 517.—

Unricy, Geol. Sury. Illinois, vol. 8, 1890, p. 304, figs. 2 ch.

Rhinidictya mutabilis ULricH, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 125, pl. 6, figs. 1-6, 12, 13; pl. 7, figs. 10-23, 25-28; pl. 8, figs. 1-3.—
WuitkAves, Pal. Foss., vol. 3, 1897, p. 240.—SarprEson, Journ. Geol., vol.
9, 1901, p. 155, pl. B, figs. 4-6.

Stictopora mutabilis var. minor Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist.
Surv. Minnesota, vol. 3, pt. 1, 1886, p. 67.

a

Ah OTT h

Fic. 56.—RHINIDICTYA MUTABILIS. G@, A YOUNG SPECIMEN, DESCRIBED AS VARIETY MINOR, NATURAL SIZE;
b, THE USUAL MATURE SPECIMEN; C, SURFACE VIEW, X9, OF A YOUNG EXAMPLE; d, SEVERAL APERTURES
OF THE SAME, X35; €, SURFACE OF ORIGINAL OF FIGURE b, X9. BLACK RIVER (DECORAH) SHALES, MINNE-
APOLIS, MINNESOTA. (AFTER ULRICH.)

This is a most abundant bryozoan in the Black River (Decorah)

shales of Minnesota and Iowa; in fact, specimens are so numerous
that one particular bed has been designated the Rhinidictya bed.
The large amount of material studied by Ulrich caused him to recog-
nize in addition to the typical form three varieties, minor, major, and
senilis. In his final work upon the subject, variety minor was re-
duced to synonymy under the type form of the species on the grounds

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 133

that the specimens so designated were only young examples. Curi-
ously enough, most of the specimens found in the Baltic strata are
a number of examples from the Wassalem beds at Uxnorm, differing
in no appreciable manner from the types of the variety minor. It
is probable that this is only an accidental coincidence, and that in
the course of time specimens of the more mature typical form of the
species will be discovered. The surface characters of both the type
form of the species and of the young examples designated variety
minor are illustrated in the accompanying figures. The species is
described in considerable detail by Ulrich, but it is believed that the
narrow, bifoliate, ribbon-like stipes bearmg longitudinal rows of
somewhat elongated quadrate zocecia, with granulose separating
ridges, are sufficient to distinguish it from most associated bryozoans.

Fig. 57.—RHINIDICTYA EXSERTA. @ AND 6b, TWO TYPICAL FRAGMENTS, NATURAL SIZE; €, TANGENTIAL SEC-
TION, X20, THROUGH MATURE ZONE OF AN OLD EXAMPLE; d, VERTICAL SECTION, X20, OF THE SAME SPECI-
MEN. WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

The internal structure is very similar to Rhinidictya exserta, illustrated
above. Comparisons between the two are given on page 134.

Occurrence.—Very abundant in all the divisions of the Black River
(Decorah) shales, and in the Fusispira and Nematopora beds of the
lower Trenton limestones of Minnesota and Iowa; common in the
Wassalem beds (D3) at Uxnorm, Esthonia (Cat. No. 57227, U.S.N.M.)

One specimen (forma minor) from the Wassalem beds at Uxnorm
in the collections of the British Museum.

RHINIDICTYA EXSERTA (Eichwald).
Text figs. 57, 58.

Eschara exserta E1cHwALD, Urwelt Russlands, pt. 2, 1847, pl. 1. fig. 2.
Stictopora exserta EICHWALD, Lethzea Rossica, vol. 1, 1860, p. 392, pl. 26, fig. 11a, 6.
As shown in figure 58, the two illustrations of Stictopora easerta
given by Eichwald seem to represent the surface of quite different
bryozoans. I am unable to find any form corresponding to figure

134 BULLETIN 77, UNITED STATES NATIONAL MUSEUM. ;

58 a, but figure 58 6b in all probability refers to a species of Rhini-
dictya not uncommon in the Wesenberg limestone, for which I shall
adopt the name Rhinidictya exserta.

The zoarium of Rf. exserta is of narrow, parallel-edged branches,
24 to 3 mm. in width, dividing dichotomously at intervals of 15 mm.
ormore. Zocecia with oblique to nearly direct oblong apertures, five
to six in 2 mm., measuring longitudinally, and 11 m the same distance
counting transversely. As often noted in this genus, the marginal
rows of apertures are usually a little larger than the average and are
directed outward. In young examples the zocwcial interspaces are
thin and without surface ornament; with age they thicken slightly
and exhibit rows of small granules. The latter appear clearly in
tangential sections, as indicated in figure 57 ce.

The internal structure of this species is very similar to that of R.
mutabilis, which has been so
fully described by Ulrich that
there is no necessity for repe-
tition. The median tubuli
are seen best in transverse
sections and are not shown

a

trations. The surface char-
acters of the species, although
Pes mire, © Dorr’ oul faidly well glow aaa

SPECIMEN, UPON WHICH THE PRESENT CONCEPTION OF wald’s fioure 58 b, are per-

yr US i hire eda haps better illustrated in
Ulrich’s view of R. mutabilis in figures 56 ¢ and d. In spite of this
similarity, there need be no difficulty in distinguishing FR. exserta
because its zocecia are one-fourth to one-third again as large as those
of R. mutabilis.

The bifoliate, narrow, straight edged parallel branches of f&.
exserta, with its oblong zocecia, are so distinct from associated bryo-
zoans that there is little likelihood of confusing it with any other.
In contrast with other bryozoans of the Wesenberg limestone, all of
the specimens of the present species that I have seen have weathered
out with a distinct white color, a fact which also aids in their identi-
fication.

Oceurrence.—Apparently common in the Wesenberg limestone (EK)
at Wesenberg, Esthonia; rare in the Kegel limestone (D2) at Kegel,
Esthonia.

Plesiotypes.—Cat. No. 57228, U.S.N.M.

British Museum, one specimen from the Wesenberg limestone at
Wesenberg.

in the accompanying illus-

oo

a

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 135

Genus PHYLLODICTYA Ulrich.

Phyllodictya Unricn, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 153.—M11-
LER, North Amer. Geol. and Pal., 1889, p. 315.—Uturicu, Geol. Surv. Illi-
nois, vol. 8, 1890, p. 390; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, 1893,
p- 141; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 280.—Stmpson,
Fourteenth Ann. Rep. State Geologist New York for the year 1894, 1897, p.
531.—Nickizes and Basster, Bull. 173, U. 8. Geol. Surv., 1900, p. 49.

The members of this genus differ from other Rhinidictyonide
in having broad, bifoliate zoaria with long zoccial tubes crossed by
complete diaphragms
and without hemisepta.
Its relations are mainly
with Pachydictya, but
Phyllodictya has more or
less strongly oblique
apertures with the pos-
terior edge raised. Of
the two known Russian
species, one is identical
with an American form,
while the second is new.

Genotype.—Phyllo-
dictya frondosa Ulrich.
Middle Ordovician
(Black River) of the
United States and Can-
ada.

PHYLLODICTYA FLABEL-
LARIS, new species.

Plate 7, figs. 7, 8; text fig. 59.

This fine new species

differs from all other Fig. 59.—PHYLLODICTYA FLABELLARIS. @, VERTICAL SECTION,
members of the genus X20, SHOWING THE LONG, ZOGCIAL TUBES; b, MINUTE STRUC-
= : TURE OF THE INTERZOGCIAL SPACES, X60; Cc, TANGENTIAL SEC-
in the greater dimen- TION, X20, WITH PORTION OF A MACULA AND ADJOINING
sions of both the Z0a~ ZOG@CIA; d, SEVERAL ZOG:CIA OF THE SAME SECTION, X30.
2 : ORTHOCERAS LIMESTONE (B3), BALTISCHPORT, ESTHONIA.

rium and zoecia. The

/zoarium is a broad bifoliate expansion of which figure 7 on plate 7

represents only a fragment. The original of this type-specimen must
have been at least 40 mm. in height and 60 mm. in width, with a
maximum thickness of 4 mm. Another specimen before me has a
still greater thickness, so that its other dimensions were probably
correspondingly larger. The surface of these zoaria is marked by
finely granular solid spots or macule at intervals of about 5 mm.
The more perfect condition of the surface shows the zoccia to be
arranged in longitudinal series between faintly papillose ridges, but in
old examples this arrangement is much obscured. Four zoccia

136 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

in 2 mm. measuring longitudinally. Indeed the apertures show the
same variation as exhibited in the several illustrations of the following
P. varia.

Aside from the larger zocecia the internal structure is also much as
in P. varia. In vertical section the zocecial tubes proceed to the sur-
face in a long, gentle curve. Neither diaphragms nor hemisepta
have been observed in any of the sections. The zocecial interspaces
are filled with a dense, laminated tissue which, as shown in figure 59,
is pierced by numerous tubuli. In tangential sections these tubuli
appear as dark spots or pores, numerous in the macule, but less
common between the zowcia. The zocecia in such sections are
rounded to elongate oval and drawn out anteriorly with the walls
thickened by the interzocecial deposit of tissue.

Compared with P. varia, the only other Russian species of the genus,
P. flabellaris has larger zocecia, a broader and thicker zoarium and
more conspicuous macule. Other bifoliate bryozoans of the Baltic
area are too different to require comparison.

Occurrence.—Not uncommon in the Orthoceras limestone (B3) on
the island of Rogo, near Baltischport; also at Baltischport, and at
Tischer, near Reval, Esthonia.

Cotypes.—Cat. Nos. 57230, 57231, U.S.N.M.

Thin sections of specimens from Baltischport are in the British
Museum’s collection.

PHYLLODICTYA VARIA Ulrich.
Text fig. 60.
Phyllodictya varia Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 144, pl. 14, figs. 1-8.

A second species of Phyllodictya in the Middle Ordovician strata of
Russia differs conspicuously from the preceding form in having
smaller zocecia and a more delicate zoarium. ‘This particular species
was found to agree in all essential respects with the very common
Minnesota Ordovician form described by Ulrich as Phyllodictya varia.

In fact, the similarity is so great that 1t was thought unnecessary to.

show any other illustrations than those given by Ulrich. The zoarium
is of bifoliate, thin, leaf-like expansions, with sharp, nonporiferous,
subparallel edges. Scattered over the celluliferous surfaces at dis-
tances of about 4 mm. are solid, finely granostriate maculz which,
in old specimens, as shown in figure 60 e, are of considerable size.
The normal shape and arrangement of the zoecia, with their surface
ornamentation, is shown in figures 60 ¢ and 60d, while the usual
views seen in vertical and tangential sections are reproduced in figures
60 f and g. Measuring longitudinally, five to six apertures may be
counted in 2 mm.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 137

Occurrence—The American types of this species seem to be
limited to the Rhinidictya bed of the Black River (Decorah) shales of
Minnesota. The Russian examples studied were found in the Was-
salem beds (D3) at Uxnorm (Cat. No. 57233, U.S.N.M.).

British Museum, one specimen from the Wassalem beds at Ux-
norm.

ingheta

‘
€
ut

OF

AN ey

mi paced 9
ay
ares +

Fic. 60.—PHYLLODICTYA VARIA. @, PORTION OF A LARGE ZOARIUM, NATURAL SIZE; 0, FRAGMENT WITH SUB-
PARALLEL MARGINS, NATURAL SIZE; c, SURFACE OF THE SAME, X9; d, TWO ROWS OF APERTURES, X18,
SHOWING THE PAPILLOSE CHARACTER OF THE RIDGES; €, SURFACE OF AN OLD ZOARIUM, X9, EXHIBITING
DISTINCT MACUL; f, VERTICAL SECTION, X18; g, TANGENTIAL SECTION, X18. BLACK RIVER (DECORAH)
SHALES, MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

Genus PACH YDICTYA Ulrich.

Pachydictya Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 152.—
Forrste#, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 162.—MituEr, North
Amer. Geol. and Pal., 1889, p. 313.—Uuricu, Geol. Surv. Illinois, vol. 8,
1890, pp. 390, 522; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893,
p. 145.—Smeson, Fourteenth Ann. Rep. State Geologist of New York for
the year 1894, 1897, p. 530.—Nickirs and Basser, Bull. 173, U. 8. Geol.
Surv., 1900, p. 48:—Basstzr, Bull. 292, U. 8. Geol. Surv., 1906, p. 57.—
Hewnnic, Archiv fur Zool., K. Sven. Vet.-Akad. Stockholm, vol. 2, No. 10,
1905, p. 25.—Cumines, Thirty-second Ann. Rep. Dep. Geol. Nat. Res. In-
diana, 1907, p.*751.

All of the four species of Pachydictya found in the Baltic strata
prove to belong to that section of the genus in which the zoarium is

138 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

marrow with subparallel margins and the longitudinal arrangement
of the zocecia predominates. The type species of the genus has a
broad, palmate zoarium, but its internal structure is essentially the
same as in the narrow, branched forms. The zocecial apertures in
Pachydictya are oval and have well-marked, ring-like walls, this
character alone being so marked that it serves as a distinction from
other genera of the Rhinidictyonide.

Genotype.—Pachydictya robusta Ulrich. Middle Ordovician (Ot-
tosee) shales of east Tennessee.

FiG. 61.—PACHYDICTYA ELEGANS.—a, TANGENTIAL SECTION, X18, CUT OBLIQUELY SO AS TO SHOW PARTS OF
BOTH SIDES OF THE ZOARIUM. THE UPPER THIRD EXHIBITS THE STRUCTURE OF THE FULLY MATURED
ZONE, WHILE A LESS MATURE PORTION IS SHOWN IN THE LOWER PART. THE SHADED AREA WITH SHORT,
PARALLEL LINES REPRESENTS THE MEDIAN LAMINA WITH ITS LONGITUDINAL TUBULI; 6, A SINGLE ZO@CIUM
OF THE SAME SECTION, X35. CLITAMBONITES BED OF LOWER TRENTON, ST. PAUL, MINNESOTA. 6,
TRANSVERSE SECTION, X18, PACHYDICTYA FOLIATA, SHOWING THE MEDIAN TUBULI DISTINCTLY. Brack
RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.)

PACHYDICTYA ELEGANS Uhrich.
Text figs. 61, 62.
Pachydictya elegans Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol 3; ping:
18938, p. 154, pl. 8, figs. 18, 19; pl. 9, figs. 8, 9.

Among the several species of Pachydictya found in the strata of
the Baltic provinces is one represented by a few well-preserved speci-
mens which I am unable to distinguish from the abundant form in
the Clitambonites bed of Minnesota described by Ulrich as P. elegans.
Views of an American and a Russian example are given in figure

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 139

62 a and ¢, while the surface characters of the former are shown in
figure 626. The zoarium grows from a spreading attached space
into narrow, bifoliate branches with thin, sharp, nonporiferous edges.
When magnified the celluliferous side in the very regular arrange-
ment of the zoccia and sculpture of the interspaces presents a highly
ornamental appearance. The apertures are elliptical and separated
from each other by spaces equal to their shorter diameter. Around
each aperture is a well-defined peristome, and between the longitudi-
nal rows of zocecia a flexuous, thread-like line is developed. These
peristomes and longitudinal lines bear a row of minute papille, which
increase the ornament of the surface. Five to five and one-half
zocecia In 2 mm., measuring lengthwise, and seven rows in 2 mm.,
counting transversely.

Fig. 62.—PACHYDICTYA ELEGANS. a@, NEARLY COMPLETE ZOARIUM, NATURAL SIZE, BRANCHING MORE
FREQUENTLY THAN USUAL; b, ENLARGEMENT OF SURFACE OF SAME, X18, SHOWING ORNAMENTATION.
LOWER PART OF TRENTON LIMESTONE, ST. PAUL, MINNESOTA; Cc, FRAGMENT, X1.5, WITH YOUNG STREP-
TELASMA ATTACHED. WHESENBERG LIMESTONE WESENBERG, ESTHONIA.

In size of zocecia and general aspect of the zoarium, P. elegans is
quite similar to the associated P. flabellum. A surface view of the
zocecia enlarged, as shown in figures 62 b and 63 6, will readily dis-
tinguish them, since P. elegans has oval cell apertures with a well-
marked peristome and highly ornamental interspaces. In thin sec-
tions P. flabellum shows the regular oval zoccia of Pachydictya, but
at the surface they appear to be inclosed in rather regular hexagonal
areas formed by the union of the lines in the interspaces. All of the
other Baltic species of Pachydictya have larger zocecia.

Occurrence—Abundant in the Clitambonites bed of the lower
Trenton of Minnesota and Iowa. Fairly abundant in the Kuckers
shale (C2), Baron Toll’s estate, and in the Wesenberg limestone (KE)
at Wesenberg, Esthonia.

Plesiotype.—Cat. No. 57234, U.S.N.M.

Specimens and thin section from the Wesenberg limestone at
Wesenberg in the collections of the British Museum.

92602°—Bull. 77—11——i1

140 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

PACHYDICTYA FLABELLUM (Leuchtenberg).
Plate 8, fig. 1; text figs. 63, 64.

Eschara flabellum LeucHTENBERG, Geognosie de Russie, p. 370.
Stictopora flabellum Excuwaup, Lethza Rossica, vol. 1, 1860, p. 391, pl. 24,
fig. 14 a-c.

The particular bryozoan that Leuchtenberg had in mind when
describing Eschara flabellum can probably never be determined, and
our knowledge of this species must date from Eichwald’s work.
Although Eichwald’s description leaves much to be desired, his
figures agree exactly, so far as they go, with an abundant bryozoan
of the Wesenberg limestone belonging to the genus Pachydictya. I
have figured this species in some detail, and will call attention to
the various illustrations in giving its specific characters.

As shown in figure 1 of plate 8, the
zoarium is of thin, bifoliate, ribbon-like,
eraceful branches, less than 5 mm.
wide, dividing dichotomously at inter-
valsof 15mm. The margins are acute
and usually have a finely striated bor-
der. The width of these marginal bor-
ders increases with age, as illustrated

in Eichwald’s view of the surface (fig.
Fic. 63.—PACHYDICTYA FLABELLUM. @, ‘
FRAGMENT, NATURAL size; b, suRFacEoF 93 b). The zoccial apertures are oval

SAME, ENLARGED, SHOWING THE SOME- with a poorly developed Sri oe! or

WHAT ANGULAR ZOGCIA AND PORIFEROUS,
NONCELLULIFEROUS BORDERS; c, TRANS-
VERSE VIEW OF BRANCH. ‘‘CALCAIRE A
ORTHOCERATITES,’’ PULKOWA, GOVERN-
MENT OF ST. PETERSBERG. (COPIED
FROM EICHWALD’S FIGURE OF STICTO-

peristome which is usually inconspicu-
ous because the lines of the interzocecial
spaces unite to form a hexagonal area
about each aperture. This, as is evi-

PORA FLABELLUM.) : 5 5
dent in Eichwald’s figure, gives an ap-

parent polygonal outline to the zocecia, and, moreover, makes the
species easy of recognition. Measuring longitudinally, five to six
apertures occur in 2 mm.

The internal structure is much as in other species of Pachydictya
of similar growth. The vertical sections show unusually large
vesicles filling the early portions of the interzoccial spaces, but these
are soon replaced by the solid, laminated tissue pierced by the minute
tubules. Tangential sections passing near the surface of old ex-
amples exhibit oval zocecia with a narrow peristome, separated by
broad, interzocecial spaces bearing numerous tubules (fig. 64 a). In
ficure 64 6 a deeper portion of a tangential section is illustrated with
the lower half passing through the vesicular zone. In certain sec-
tions, especially of young examples, the vesicles have the appearance
of mesopores (fig. 64 ¢).

The only species with which P. flabellum may be confused is the
equally abundant P. elegans. Comparisons between the two are
given under the description of the latter.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 14]

Occurrence.—Kichwald records the species from Poulkowa. All of
the specimens before me come from the Wesenberg limestone (E) at
Wesenberg, Esthonia.

Plesiotypes—Cat. No. 57236, U.S.N.M.

British Museum, specimens and thin sections from Wesenberg
limestone, at Wesenberg, Esthonia.

Fic. 64.—PACHYDICTYA FLABELLUM. d@, TANGENTIAL SECTION, X20, THROUGH AN OLD PORTION OF THE
ZOARIUM; 6, ANOTHER TANGENTIAL SECTION, X20, SHOWING THE APPEARANCE IN THE EARLY PORTION
OF THE MATURE ZONE; C, TANGENTIAL SECTION OF A YOUNG EXAMPLE, X20, WITH OPEN MESOPORES;
d, THE USUAL ASPECT OF VERTICAL SECTIONS, X20; ¢, VERTICAL SECTION, X20, OF YOUNG SPECIMEN.
W ESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

PACHYDICTYA CYCLOSTOMOIDES (Eichwald).
Text figs. 65, 66.
Micropora cyclostomoides Excawaxp, Bull. Soc. Nat. Moscou, No. 4, 1855, p. 459;
Letheea Rossica, vol. 1, 1860, p. 394, pl. 24. fig. 16 a, 6.

Hichwald’s figures of Micropora cyclostomoides clearly indicate a
broad, branching species of Pachydictya, with rather large apertures.
His types were registered from the ‘‘calcaire & Orthoceratites de
Wesenberg et d’Erras.”’ This would imply, although not necessarily

.

142 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

correctly, that his specimens were derived from the Wesenberg lime-

stone. Pachydictya elegans, a species corresponding to his figures of

M. cyclostomoides in some respects, is present in the Wesenberg lime-

stone, and it is possible that Eichwald had this species before him.

However, in view of the uncertainty of accurate identification, I have

decided to adopt Hichwald’s name, not

to replace the American P. elegans,
but for a common bryozoan in the

Kuckers shale and higher formations,

differing mainly in having larger zowe-

cia, a less ornamented surface, and a

broader zoarium. If Hichwald’s fig-

ures can be relied upon, he probably

‘ illustrated this large-celled species.

Fic. 65—PACHYDICTYA CYCLOSTOMOIDES. Je achydictya cyclostomordes, as here
EICHWALD’S VIEW OF Microrora cy- identified, forms rather broad, bifoliate
CLOSTOMOIDES. @ AND, cuEN” ‘branches 5 mm. or more in diameter
NATURALSIZE, AND A PORTION ENLARGED. ?
“CatcaRe A OrTHocERaTITEs” Wesen- frequently and irregularly dividing.
ee The surface is smooth but, unlike the

other branching Baltic species of the genus, distinct macule are oc-
casionally developed. The zocecia are large, oval, thick walled, and
have a conspicuous peristome; three zocecia in 2 mm., measuring lon-
gitudinally, five rows of apertures in the same distance. The aper-
tures are arranged in rather regular longitudinal series which are most
interrupted when a macuza is inserted.

Fic. 66.—PACHYDICTYA CYCLOSTOMOIDES. ad, TANGENTIAL SECTION, X20, SHOWING THE LARGE OVAL
ZOGCIA; 6, VERTICAL SECTION, X20. JEWE LIMESTONE (D1), ST. MATHIAS, ESTHONIA.

The internal structure is that of a typical Pachydictya. In tangen-
tial sections the large size of the zowcia and the wide end spaces
separating them are the important features aside from the ring-like
walls. Vertical sections show a few diaphragms in the zoccial tubes
and a profuse development of vesicles and laminated tissue in the
interzocecial spaces.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 143

The large oval zoccia and broad branches with macule will dis-
tinguish P. cyclostomoides from the other Baltic species. Among the
American forms none of those with a similar growth has zoecia of
the same size.

Occurrence.—As stated above, Eichwald records the species from
Wesenberg and Erras. Specimens which I have identified with it
occur abundantly in the Kuckers shale (C2), Baron Toll’s estate;
in the Jewe limestone (D1), St. Mathias; and in the Kegel limestone
(D2) at Kegel, Esthonia. The species is also present in the Chasmops
limestone at a locality on the island of Oeland, south of Bédahamn.

Plesiotype-—Cat. No. 57238, U.S.N.M.

Specimens from the Jewe limestone, St. Mathias, Kuckers shale,
Baron Toll’s estate, and from the Chasmops limestone, island of
Oeland, are in the British Museum collections.

PACHYDICTYA BIFURCATA (Hall).
Text figs. 67, 68.

Stictopora bifurcata Hatt, Twelfth Ann. Rep. Indiana Geol. Nat. Hist., 1883,
Oy AAT, valle By ses, ah, 4

Pachydictya bifurcata Forrste, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 163;
vol. 3, 1888, pl. 15, fig. 10; Geol. Surv. Ohio, vol. 7, 1895, p. 599, pl. 28, fig. 9.

Stictopora scalpellum Ercawaup (not Lonsdale), Letheea Rossica, vol. 1, 1860,
p. 390, pl. 24, fig. 15 a-e.

Rhinidictya ? Borkholmiensis Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2,
No. 10, 1901, p. 180, pl. 6, figs. 1-7.

Fig. 67.—PACHYDICTYA BIFURCATA. @ AND b, TWO FRAGMENTS, X1.5;¢, TANGENTIAL SECTION, X20,
SHOWING THE DISTINCT PERISTOME, THICK WALLS, AND WIDE INTERSPACES; d, PORTION OF A TRANSVERSE
SECTION, X20, WITH WELL-MARKED MEDIAN TUBULI. LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND OF
DaGo, ESTHONTA.

The Lyckholm and Borkholm limestones contain numerous exam-
ples of a narrow, parallel edged Pachydictya which agrees in all of its
characters with a common American Clinton species described by

144 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Hall as Stictopora bifurcata. A specimen, probably of the same
species, was illustrated by Hichwald as Stictopora scalpellum (Lons-
dale), although this identification on my part is merely a guess,
based upon the fact that Eichwald’s figured example came from the
island of Dago, and evidently represents the old condition of Pachy-
dictya bifurcata. At any rate, it is almost certain that Eichwald’s
Stectopora scalpellum does not refer to the Wenlock species described
by Lonsdale. )

Although closely allied to such species of Pachydictya as P. elegans
and P. cyclostomoides, the present form may: be distinguished, first,
by its regular parallel edged branches, usually 5 mm. in width, divid-

Fig. 68.—PACHYDICTYA BIFURCATA. @ TO g, WIMAN’S FIGURES OF RHINIDICTYA BORKHOLMIENSIS. @
To d, FOUR FRAGMENTS, NATURAL SIZE; €, SURFACE OF FRAGMENT, X10; /, VERTICAL SECTION, X10; g,
TRANSVERSE SECTION, X10. BORKHOLM DRIFT, “OJLE MYR, ISLAND OF GOTHLAND; h T0j, EICHWALD’S
FIGURES OF STICTOPORA SCALPELLUM; h, FRAGMENT, NATURAL SIZE; 7, SURFACE ENLARGED; j, END
VIEW OF SAME. BORKHOLM LIMESTONE, ISLAND OF DAGo.

ing dichotomously at rather long intervals; second, by its large, oval,
thick-walled zocecia, of which there are four to four and one-half in
2 mm., measuring longitudinally; and third, by the broad, granulose
interspaces separating the apertures at both their ends and sides.
P. cyclostomoides has still larger zocecia and differs further in its
broader, more frequently branching zoarium. The other species have
smaller zocecia and a different surface ornament. :
Rhinidictya * borkholmiensis Wiman is in all probability a synonym
of the present form. This species is recorded by Wiman as a very
common fossil of the drift bowlders at Ojle Myr, on the island of
Gothland, and in the Borkholm limestone at Borkholm, Esthonia.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 145

Wiman’s figures, here reproduced, represent a species of Pachydictya
with surface characters identical with P. bifurcata. Young specimens
of P. bifurcata in the collection from the Borkholm limestone at
Borkholm have considerable similarity to Wiman’s figured examples,
and this leads me to believe in the identity of the two species.

Occurrence—Abundant in the Silurian (Clinton) limestone at
Dayton and other localities in Ohio and Indiana. Equally abundant
in the Lyckholm limestone (F1) at Kertel, on the island of Dago, and
at Lyckholm, Esthonia; in the Borkholm limestone (F2) at Bork-
holm, Esthonia; Borkholm drift, Ojle Myr, island of Gothland.

Plesiotypes.—Cat. No. 57240, U.S.N.M.

Specimens from the Borkholm limestone, Borkholm, Esthonia, and
from the Lyckholm limestone, island of Dago, in the collections of
the British Museum.

Family CYSTODICTYONID Ulrich.

No genus of this family has hitherto been recorded from rocks
older than the Middle Devonian, yet a single specimen from the
Orthoceras limestone on the island of Rogo possesses all the char-
acters of typical Coscinium. The Cystodictyonide in all probability
are derived from the Rhinidictyonide, from which they differ most
conspicuously in having a more or less well developed lunarium. It
is possible that this appearance of Cosciniwm in the Middle Ordovician
represents an early expression of this line of descent and that the
characters were still too unstable to survive for any time.

Genus COSCINIUM Keyserling.

Coscintum Kryseruine, Reise in das Petschora Land, 1846, p. 191.—Prout,
Trans. St. Louis Acad. Sci., vol. 1, 1858, p. 266.—Utricu, Journ. Cincinnati
Soc. Nat. Hist., vol. 7, 1884, p.38.—Hatt and Simpson, Nat. Hist. New York,
Pal., vol. 6, 1887, p. xix.—Mruer, North Amer. Geol. and Pal., 1889, p. 298.—
Uxricy, Geol. Surv. Illinois, vol. 8, 1890, pp. 385, 496.—Simpson, Fourteenth
Ann. Rep. State Geol. New York for the year 1894, 1897, p. 537.—NIcKLES
and Basster, Bull. 173, U. 8. Geol Surv., 1900, p. 50.

Coscintum HicHWALD (part), Letheea Rossica, vol. 1, 1860, p. 397.

Coscinotrypa Hatu and Simpson, Nat. Hist. New York, Pal., vol. 6, 1887, p. xix.—
Minter, North Amer. Geol. and Pal., 1889, p. 298.—Srmupson, Fourteenth
Ann. Rep. State Geol. New York for the year 1894, 1897, p. 537.

Species of Coscinium differ from other genera of the family notably
in having a cribrose zoarium. ‘This, in connection with the bifoliate
growth, round zocecia with conspicuous lunaria and solid interspaces,
makes the recognition of the genus easy. Five or six species are
known from Devonian and Carboniferous rocks.

Genotype.— Coscinium cyclops Keyserling. Carboniferous of Russia.

146 BULLETIN 7, UNITED STATES NATIONAL MUSEUM.

COSCINIUM PRZNUNTIUM, new species.

Plate 7, figs. 5, 6; text fig. 69.

Zoarium a bifoliate, flabellate, cribrose frond, 30 or more mm. high
and the same width, growing from an expanded base attached to
foreign bodies. The individual branches are 2mm.in width and 1 mm.
thick. An average
fenestrule is broadly
oval in outline and is
2 mm. long and 1.5
mm. wide. Base of
zoarlum and margins
of branches noncellu-
liferous and finely
granulose. Apertures
subpyriform to trilo-
bate in outline with a
distinct lunarium oc-
cupying the posterior
third or fourth. An
average zoceclum is

Fic. 69.—COSCINIUM PRHNUNTIUM. @, TANGENTIAL SECTION, X20; 0, 0.24 mm. long; five
VERTICAL SECTION, X20. ORTHOCERAS LIMESTONE (B3), ISLAND in 2 mm measuring
=)

oF RoGo, ESTHONIA.
lengthwise. Inter-
zocecial spaces as wide and often wider than the zoecia, solid at
the surface, granulose or granulostriate.

Coscinium prenunttum has a smaller zoarium than the later
representatives of the genus. It differs too decidedly from other
Ordovician forms to require comparison.

Occurrence.—Rare in the Orthoceras limestone (B3), island of
Rogo, Esthonia.

Holotype.—Cat. No. 57243, U.S.N.M.

Specimen and thin sections in the British Museum.

Family ARTHROSTYLIDA Ulrich.

Zoarium articulated, consisting of numerous subcylindrical seg-
ments, united into small pinnate or bushy colonies, or of contmuous,
dichotomously divided branches; zoccia subtubular, more or less
oblique, radially arranged about a central axis, and opening on all
sides of the segments; or one side may be noncelluliferous and longi-
tudinally striated.

Both the zocecial and zoarial characters of the Arthrostylide are
so distinctive that thin sections are seldom necessary for accurate
specific determination. It is surprising that of the 12 species of the
family identified in Russian strata, 10 are characteristic American
forms.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 147

Genus ARTHROSTYLUS Ulrich.

Arthronema (preoccupied) Unricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882,
pp. 151, 160.

Arthrostylus Utricu, American Geologist, vol. 1, 1888,p. 230; Journ. Cincinnati
Soc. Nat. Hist., vol. 12, 1890, p. 188; Geol. Surv. Illinios, vol. 8, 1890, p. 400;
Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 187; Zittel’s
Textbook of Paleontology, (Eng. ed.), 1896, p. 280.—Simpson, Fourteenth
Ann. Rep. State Geologist New York for the year 1894, 1897, p. 527.—
NiIcKLES and Basser, Bull. 173, U.S. Geol. Surv., 1900, p. 42.—Cumtnes,

Thirty-second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 740.
This interesting member of the Arthrostylide is represented in the
Russian collections by a few individuals which can be referred to the
two American Black River species, A. conjunctus and A. obliquus of
Ulrich. These specimens consist of free segments
of the zoarium, pointed at one end for articulation
with the preceding segment, and with a socket-like
hollow at the otherend. The complete zoarium in
Arthrostylus consists of numerous very small sub-
quadrate segments united by terminal articulation
and branching dichotomously until a small pinnate
or bushy colony is the result; each of these seg-
ments has one of its faces longitudinally striated
and each of the other faces, of which there are com-
monly three, bears a linear series of apertures be-

tween longitudinal ridges. FIG. 70.—ARTHR OSTY-
* : L LUS CONJUNCTUS. @,

Genotype. elopora tenuis James. Warliest | oa wewort,
Silurian (Richmond) of the United States. CENTRAL PORTION OF
A SEGMENT, X18; 0,

ARTHROSTYLUS CONJUNCTUS Ulrich. SMALL PORTION OF

NONCELLU LIFEROUS

Text fig. 70. SIDE OF SAME, X18.

BLACK RIVER (DECO-

Arthrostylus conjunctus Utricu, Journ. Cincinnati Soc. Nat. RAH) SHALES, NEAR

Hist., vol. 12, 1890, p. 189, fig. 14; Geol. and Nat. Fountain, rege a
Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 188, pl. 3, ae saieus pee
figs. 13, 14.—Simpson, Fourteenth Ann. Rep. State

Geologist New York for the year 1894, 1897, p. 526, figs. 78, 79, 79a.

This and the following species of Arthrostylus have been briefly but
clearly described by Ulrich in his memoir on the Bryozoa of Minnesota,
and, as the Russian examples referred to these two species differ in
no appreciable way, I have in each case made use of his description.

Original description.—Zoarium jointed; segments very slender, straight, needle-
shaped, 3 or 4mm. long, quadrangular in cross section, 0.25 mm. wide, 0.18 mm. thick,
with zocecial openings on three sides, the fourth being without them, but marked
instead with four parallel longitudinal striz. Zocecial apertures broad-oval, direct, ©
0.11 mm. long, 0.09 mm. wide, inclosed by a sharply marked peristome. Peristomes
of each row of apertures joined together by a thin ridge, having a length about equal
to the larger or outer diameter of the peristomes. Hight zocecial apertures in each
rowin2.5mm. A thin ridge on each side of the range of apertures of the obverse face
of the segment separates it from the lateral rows. Apertures usually arranged alter-
nately in the three rows.

148 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Occurrence.—The American type of the species was obtained in the
Phylloporina beds of the Black River (Decorah) shales near Fountain,

Minnesota.

U.S.N.M.)

A single fairly well preserved specimen has been noted
in the Wassalem beds (D3) at Uxnorm, Esthonia.

(Cat. No. 57244,

ARTHROSTYLUS OBLIQUUS Ulrich.

Text fig. 71.

Arthrostylus obliquus Unrica, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890,
p. 190, figs. 14 ¢, d; Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1898,
p. 188, pl. 3, figs, 15, 16.

Original description.—Zoarium jointed, segments very slender, needle-shaped,
straight or slightly curved, about 4 mm. long, subquadrangular in cross section, 0.2 mm.

Fig. 71.—ARTHRO-
STYLUS OBLIQUUS.
@, SIDE VIEW OF
PORTION OF A SEG-
MENT, X18; B,
NONCELLULIF ER-
OUS SIDE, X18, OF
THE UPPER POR-
TION OF A SEG-
MENT. BLACK
RIVER(DECORAH)
SHALES, MINNE-
APOLIS, MINNE-
SOTA. (AFTER
ULRICH.)

wide, 0.15 mm. thick, slightly expanding toward the upper ex-
tremity. Zooecia in three rows, occupying as many faces of the
segment, the fourth side with three longitudinal striz, and no
zocecia. Profile of a segment in an obverse or reverse view, Wavy
on both sides; in a lateral view only on one side.

Zocecial apertures small, oblique, the posterior margin very
prominent, arranged alternately in the three rows, with nine in
each, in 2.5mm. A short ridge from the upper depressed edge of
each zocecial aperture is flanked on each side by the prolonged
lateral borders of the aperture. No ridge between the lateral and
central row of the zocecia.

The isolated joints of this small but neat bryozoan
are so inconspicuous that they are very likely to be
overlooked in collections. The species is very similar
to the preceding Arthrostylus conjunctus Ulrich, but
upon close examination may be distinguished by the
absence of ridges between the rows of apertures, the
prominent lower border, and especially by the oblique
zocecial apertures.

Occurrence.—Ulrich’s types of the species were found
in the Stictoporella bed of the Black River (Decorah)
shales, at. Minneapolis, Minnesota, where specimens
are rather rare. The species is also of uncommon
occurrence in the Echinospherites limestone. (C1)

at’ Archangelski, on the Wolchow River, in the government of St.
Petersburg (Cat. No. 57245, U.S.N.M.).

Specimens of this species from American localities are in the
collections of the British Museum.

Es

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 149
Genus HELOPORA Hall.

Helopora Hatt, Amer. Journ. Sci., ser. 2, vol. 11, 1851, pp. 388,389; Nat. Hist.
New York, Pal., vol. 2, 1852, p. 44.—Bitines, Cat. Sil. Foss. Anticosti, 1866,
p. 86.—Uxricu, American Geologist, vol. 1, 1888, p. 231; Geol. Surv. Illinois,
vol. 8, 1890, pp. 401, 642; Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890,
p. 191; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 189;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 280.—Smmpson, Four-
teenth Ann. Rep. State Geologist New York for the year 1894, 1897, p. 548.—
NickuEs and Basser, Bull. 173, U. 8S. Geol. Surv., 1900, p. 42 —Hznnie,
Archiv fur Zool., K. Sven. Vet.-Akad. Stockholm, vol. 3, No. 10, 1906, p. 18.

Helopora was founded upon an early Silurian species, Helopora
fragilis Hall, from the Clinton and Niagara rocks of New York and
Canada, and has its best and most typical representation in this time.
Unquestionable species of the genus are, however, present in the
Middle Ordovician, and the discovery of the following H. divaricata
Ulrich in the Kuckers shale is an interesting extension of the geo-
graphic range of the genus and species.

Helopora differs from Arthrostylus in that its segments are gen-
erally much larger and bear zocecial apertures on all sides. The ter-
tiary segments of species of Arthroclema have much in common with
Helopora, and care must be exercised in separating them.
Genotype.—Helopora fragilis Hall. Silurian (Clinton) of New York

and Canada.

HELOPORA DIVARICATA Ulrich.
Text fig. 72.

Helopora divaricata Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minne-
sota, 1886, p. 59; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893,
p- 191, pl. 3, figs. 1-3.

A number of isolated segments of this species have been observed
on the thin slabs of limestone in the Kuckers shale. None of these
happens to be as large as the American type of the species, and as
the zocecial apertures increase slightly in diameter with the size of
the segment itself, the Russian examples naturally have smaller aper-
tures. However, these specimens may be matched in the American
collection, so that there can be little doubt regarding the identity of
the Russian examples.

The jointed zoarium of Helopora divaricata is made up of sub-
cylindrical segments obtuse at both ends, about 7 mm. long and
bearing zocecial apertures, of which there are from six to eight rows,
opening on all sides. The diameter of a single segment ranges from
0.5 to 0.9 mm. The apertures number 12 i 5 mm., measuring
lengthwise, are comparatively large, oblique, and ovate in shape, and
are situated between strong longitudinal ridges. The posterior border
of the aperture is thick and prominent, and slopes backward into the

150 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

aperture next below. This border continues along the sides of the
apertures as two diverging ridges, extending to the summit of the
longitudinal crests, as shown in
the accompanying figure.

The segments of H. divaricata
are so much larger than those of
the species of Arthrostylus that
comparisons are not needed.
They might, however, be con-
founded with the tertiary seg-
ments of Arthroclema armatum.
Comparisons of the two species
are given in the description of
the latter.

Occurrence.—Helopora divari-
a cata is not uncommon in the
Fic. 72.—HELOPORA DIVARICATA. @, FRAGMENT Stictoporella bed of the Black

NATURAL SIZE AND X7; b, PORTION OF THE SAME, A :
X18; c, TRANSVERSE SECTION, X18. BLACK RIVER River (Decorah) shales at Min-
(DECORAH) SHALE, MINNEAPOLIS, MINNESOTA. neapolis and other localities in
(AFTER ULRICH.) 2 °
Minnesota, and is equally abun-
dant in the Kuckers shale (C2), Baron Toll’s estate, Esthonia (Cat.
No. 57246, U.S.N.M.).

British Museum, one specimen from the Kuckers shale, Baron Toll’s

estate.

Genus ARTHROCLEMA Billings.

Arthroclema Bittines, Pal. Foss., vol. 1, 1862, p. 54.—Uxricu, Fourteenth Ann.
Rep. Geol. Nat. Hist. Surv. Minnesota, vol. 5, 1882, p. 151; American Geolo-
gist, vol. 1, 1888, p. 232; Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p.
192; Geol. Surv. Illinois, vol. 8, 1890, p. 400; Geol. and Nat. Hist. Surv.
Minnesota, vol. 3, pt. 1, 1893, p. 197; Zittel’s Textbook of Paleontology (Eng.
ed.), 1896, p. 281.—Simpson, Fourteenth Ann. Rep. State Geologist of New
York for the year 1894, 1897, p. 546—Nickies and Basster, Bull. 173,
U.S. Geol. Surv., 1900, p. 42.

Zoarium of segments celluliferous on all sides as in Helopora, but
differing in being articulated not only terminally but also laterally in
a pinnate manner. ‘The first row of segments and the first set of
branches from these are known as the primary and secondary seg-
ments and bear articular surfaces on the sides as well as on the ends.
The tertiary or last set is articulated only at the end, and the seg-
ments of this set must, therefore, have great resemblance to those of
Helopora. Since the zoecial structure in each set of segments is
practically the same, and all three sets usually occur at the same
locality, no especial care is needed in distinguishing them.

Genotype.—Arthroclema pulchellum Billings. Middle Ordovician
(Trenton) of Canada.

—

;

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 151

ARTHROCLEMA ARMATUM Ulrich.

Text fig. 73.

Arthroclema armatum Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890,
p. 194, figs. 19 a-d (not e-h=Arthroclema pulchellum Billings); Geol. Nat.
Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 201, pl. 2, figs. 8-11, 25, 28-33;
pl. 3, fig. 7—Simeson, Fourteenth Ann. Rep. State Geologist New York for
the year 1894, 1897, p. 547, fig. 111.—Sarpzson, Journ. Geol., vol. 9, 1901,
p. 161.

This species is represented in the Russian collections by a few speci-
mens showing no lateral articulations. Had not the American form
been so well figured and represented in the collections of the United
States National Museum it would have been almost impossible to

a eG

a elapse

Fig. 73.—ARTHROCLEMA ARMATUM. @, LARGE SEGMENT OF THE PRIMARY SERIES, SHOWING A SHARPLY
DEFINED, ARTICULATING SOCKET, NATURAL SIZE, AND X18; b, OPPOSITE SIDE OF ANOTHER SEGMENT OF
THE PRIMARY SET, X18; c, A SEGMENT OF THE TERTIARY SERIES, X18; d, COMPLETE SEGMENT OF THE
SECONDARY SET, X18. LOWER PART OF THE TRENTON LIMESTONE, CANNON FALLS, MINNESOTA. (AFTER
ULRICH.)

have made such a close determination. However, the Russian speci-
mens agree exactly with the tertiary segments of Arthroclema arma-
tum, and I have no doubt that in time additional material will prove
the correctness of the determination.

These tertiary segments are 2.5 to 3.5 mm. long and 0.3 mm. or
less in diameter, five or six sided, with the angles fairly prominent, as
shown in figure 73 c, which represents the tertiary segment of an
American example, quite similar to the corresponding Russian
specimens.

The greater strength of the secondary segments, but their evidently
close relation to the tertiary ones, is indicated in figure 73 d, while
the short, compressed, irregularly shaped primary segment, with the

152 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

striated surface, strong spines, and indistinct zowcial apertures, is
shown in figures 73 a, b. Figure 73 a is especially interesting in illus-
trating not only the terminal points of attachment but also a large
lateral socket.

As noted in a previous description, this species and Helopora
divaricata are liable to be confused. Comparison of figures 72 and 73
will show differences in zocecial characters, but the best and surest
method of distinction is the discovery of a primary segment of the
Arthroclema bearing the lateral articulation.

- Occurrence.-—The isolated segments of this species are abundant in
the Nematopora bed of the lower Trenton limestone at Cannon Falls
and St. Paul, Minnesota. In Russia the species so far has been
observed only in the Glauconite limestone (B2) at Reval, Esthonia
(Cat. No. 57247, U.S.N.M.).

Represented in the collections of the British Musetat by specimens
from American localities.

Genus SCEPTROPORA Ulrich.

Sceptropora Uuricu, American Geologist, vol. 1, 1888, p. 228; Contr. Micro-Pal.
Cambro-Sil., pt. 2, 1889, p. 46; Geol. Surv. Illinois, vol. 8, 1890, p. 400;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 281.—Smmerson, Four-
teenth Ann. Rep. State Geologist of New York for the year 1894, 1897, p.
548.—NickiEs and Bassuer, Bull. 173, U. 8. Geol. Surv., 1900, p. 48.
Sceptropora was founded upon a single species, S. facula from the
Richmond rocks of Manitoba, Canada, but has since been noted in
these strata at many other localities. The discovery of numerous
undoubted examples of S. facula in the Borkholm limestone is in line
with other evidences showing the wide distribution of this Richmond
fauna. The generic characters of Sceptropora are as follows:
Zoarium of segments which become much expanded in their upper
portion and at the top have a socket for the articulation of the next
segment; lower portion striated, without apertures; upper part with
apertures all around; apertures subovate, in linear series between
longitudinal ridges.
Genotype—Scepiropora facula Ulrich. Earliest Silurian (Rich-
mond) of North America and Russia.
Since the publication of the type species of the genus, a second
specimen from the Clinton rocks of Canada has been described by
Ulrich. The Russian collections now afford a third species, differing

decidedly from the genotype but being not far removed in its charac-,

ters from the Clinton form.

EARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 153

SCEPTROPORA FACULA Ulrich.
Text fig. 74.

Sceptropora facula Utricu, American Geologist, vol. 1, 1888, p. 228; Contr. Micro-
Pal. Cambro-Sil., pt. 2, 1889, p. 46, fig. 2; Geol. Surv. Illinois, vol. 8, 1890,
p. 401, fig. 15 —WuitTEavEs, Pal. Foss., vol. 3, pt. 2, 1895, p. 117.—Smpson,
Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897,
p. 549, fig. 116.

Rather numerous specimens of this interesting bryozoan occur
scattered through the fossiliferous layers of the Borkholm limestone.
Here the species was first identified by a thin section which accident-
ally cut one of the segments. Further search in the rock awarded
well-preserved typical examples. Ulrich’s description is copied below:

Segments club-shaped, varying in length from less than 1 mm. to nearly 2 mm.;
lower half subcylindrical, about 0.23 mm. in diameter, noncelluliferous, covered with
fine, granulose, vertical striz; lower extremity bulbous, smooth; upper half cellulifer-
- ous, expanding more or less rapidly, the depressed conical top varying in diameter
from 0.7 to2mm. The apertures of the zocecia on the top are subcircular; about 0.09

Fic. 74.—ScCEPTROPORA FACULA. @, SINGLE SEGMENT OF THIS FINE SPECIES, X18; b, VERTICAL SECTION,
X18, THROUGH AN ENTIRE SEGMENT; C, TRANSVERSE SECTION, X18, CUTTING THE LOWER END OF A SEG-
MENT; d, TRANSVERSE SECTION, X18, THROUGH THE EXPANDED CELLULIFEROUS PORTION. RICHMOND
GROUP, STONY MOUNTAIN, MANITOBA. (AFTER ULRICH.)

mm. in diameter and arranged in radial series between raised lines about the large
central socket. As the zoarium expands the series increase in number by interpola-
tion. The apertures of the zoccia on the sides are ovate and a little larger, having an
average length of 0.11mm. Like those on the top, they are arranged between elevated
eranulose ridges.

None of the arthrostyloid or other Paleozoic bryozoans approaches
this species in growth or other characters. The other Russian species
of the genus is quite different, as evidenced by a comparison of figures
74 and 75.

Occurrence.—An. abundant and highly characteristic fossil of the
Richmond group at Stony Mountain, Manitoba, the island of Anti-
costi, and other Canadian localities, and in the same strata at various
localities in the United States, particularly at Wilmington and
Savannah, Ilnois. Equally abundant in the Borkholm hmestone
(F2) at Borkholm, Esthonia (Cat. No. 57248, U.S.N.M.).

British Museum, one specimen from the Borkholm limestone at
Borkholm, Esthonia.

154 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

SCEPTROPORA FRANCISCA, new species.

Text fig. 75.

Zoarium of club-shaped segments bluntly pointed at the proximal
end for articulation with the preceding segment. The average indi-
vidual segment is 4 mm. in length and expands slowly from the basal
portion to the distal end which is abruptly rounded and about 2 mm.
in diameter. All portions of the segments are cell bearing excepting
the extreme base and top, where articulation occurred. The aper-
tures are angular and arranged somewhat irregularly in rows between
longitudinal crests formed by the union and greater development of
the walls along such lines. Seven zocecia occur in 2mm. In some

tag iy.

IZE; 6, THE LARGEST SEG-
MENT, <9; Cc, BASAL PORTION OF THE SAME SPECIMEN, X20; d, TANGENTIAL SECTION, X20; e AND f, VER-
TICAL AND TRANSVERSE SECTIONS, X20, SHOWING GROWTH OF ZO@CIA FROM CENTRAL AXIS. WASSALEM-
BEDS (D3), UXNORM, ESTHONIA.

specimens certain apertures are small and irregularly angular, giving
the appearance of mesopores. These, however, are probably only
young zocecia, for thin sections show no trace of ordinary mesopores.

Aside from the different shape of the segment, vertical sections
show little difference from those of the genotype. The zocecia arise
from a distinct central axis marked by a definite line, and proceed to
the surface in a gentle curve, the walls as usual becoming thickened
in the mature zone. Transverse sections of the two species are iden-
tical. In tangential sections the zoccia are noted to have rather a
regular polygonal outline and arrangement in longitudinal rows.

The small, neat segments of S. francisca are too distinct from other
species of the genus to require comparison. The specific name is in

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 155

honor of Miss Francisca Wieser, to whom I am indebted for many
drawings illustrating this work.

Occurrence-—Not uncommon in the thin limestone layers and in
the clays of the Wassalem beds (D3) at Uxnorm, Esthonia.

Cotypes.—Cat. No. 57249, U.S.N.M.

Specimens in the collection of the British Museum.

Genus NEMATOPORA Ulrich.

Nematopora Utricu, American Geologist, vol. 1, 1888, p. 234; Geol. Surv. Illinois,
vol. 8, 1890, pp. 401, 644; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 204; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 281.—
Smmpeson, Fourteenth Ann. Rep. State Geol. New York for the year 1894, 1897,
p. 553.—Nicktss and Basster, Bull. 173, U. 8. Geol. Surv., 1900, p. 43.—
Bass ER, Bull. 292, U. S. Geol. Surv., 1906, p. 58.

Numerous specimens of Nematopora have been observed in the
Russian collections, all
of which have proved to
belong to species de-
scribed from North
America. The most con-
spicuous feature of this
genus, separating it from
the other genera of the
Arthrostylide, is that
the zoarium is continu-
ous and dichotomously
branched, with the
jointed character either

Fig. 76.—NEMATOPORA DELICATULA AND N. CONSUETA. @, ZO-

limited to the basal ex-
tremity or wanting en-
tirely. Thezocecial char-
acters are evident from

ARIUM NATURAL SIZE AND X18, OF NEMATOPORA DELICATULA;
b, TRANSVERSE SECTION OF SAME. GIRARDEAU LIMESTONE
DIVISION OF THE RICHMOND GROUP, ALEXANDER COUNTY,
ILLINOIS. (AFTER ULRICH.) ¢ AND d, TWO FRAGMENTS, NAT-
URAL SIZE AND X18, OF THE TRENTON SPECIMENS REFERRED BY
ULRICH TO N. DELICATULA AND HERE RENAMED N. CONSUETA.

LOWER PART OF TRENTON LIMESTONE, NEAR CANNON FALLS,

the variousfigures shown
MINNESOTA. (AFTER ULRICH.)

on the following pages.
Genotype.— Nematopora ovalis Ulrich. Middle Ordovician (Tren-
ton) of the United States and Russia.
NEMATOPORA CONSUETA, new name.
Text fig. 76.
Nematopora delicatula Utricu, Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 206, pl. 3, figs. 26, 27.
Not Nematopora delicatula Utricu, Geol. Surv. Illinois, vol. 8, 1890, p. 646, pl.
29, figs. 11-116.

The delicate bryozoan for which the above new name is proposed
has been confused with a very similar minute species described from
rocks at the base of the Cincinnati group in Alexander County,

92602°—Bull. 77—11——12

156 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

‘

Illinois. These particular strata are now known as the Girardeau
limestone and are of Richmond age. The Minnesota specimens
identified by Ulrich with Nematapora delicatula were found in the
Nematopora bed of the lower Trenton. While the specimens in
these rather widely separated horizons are quite similar, close com-
parison reveals sufficient differences to justify their recognition as
separate species. The similarity of the two forms is only another
example of the close relationship between the Black River, early
Trenton, and Richmond faunas, a fact which has been noted at
numerous places in this work.

Illustrations of both Nematopora delicatula and N. consueta are
shown in figure 76, and upon comparing them the latter species is
found to have apertures slightly larger, more rounded, and a trifle
exsert, although a more obvious difference lies in the greater distance
between its zocecial openings.

Occurrence.—The American types of NV. consueta were found in the
Nematopora bed of the lower Trenton near Cannon Falls, Minnesota.
In Russia, specimens are not uncommon in the Kuckers shale (C2),
Baron Toll’s estate, in Esthonia (Cat. No. 57250, U.S.N.M.).

British Museum, one specimen from the Kuckers shale, Baron Toll’s
estate.

NEMATOPORA OVALIS Ulrich.
Text fig. 77.

Nematopora ovalis Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p.
197, fig. 21; Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 204, pl.
3, figs. 24, 25.

Nematopora quadrata Utricu, Geol. Surv. Illinois, vol. 8, 1890, p. 644, pl. 29,
figs 12-12c.—Stupson, Fourteenth Ann. Rep. State Geologist of New York
for the year 1894, 1897, p. 553, figs. 124, 125.

The surface characters of this fine species are so distinct from other
forms of Nematopora that there should be little difficulty in its identi-
fication. Ulrich’s diagnosis of the species is concise and applies
equally well to the Russian specimens. ~

Original description.—Zoarium ramose; branches bifurcating at intervals of about
2mm., 0.3 to 0.4 mm. in diameter, subquadrangular or pentagonal in cross section,
each face with a row of zocecia. Zocecial apertures direct, very large, oval, nearly
0.3 mm. long by 0.15 mm. wide, inclosed by a sharply defined peristome. A short
ridge joins the peristomes of each row of apertures, and longitudinally divides the
concave spaces between the ends of the apertures. These spaces are larger in the sub-
quadrate examples than in those having five rows of zocecia. They also have the thin
ridge that bounds each face more distinct from the elevated margins or peristomes of the
zocecial apertures, which, in the pentagonal specimens, to a large extent also form the
border of the faces. Longitudinal interspaces generally shorter than the length of
the zocecial apertures; about five of the latter in 2.5 mm.

Occurrence.—The Minnesota types of the species occurred in the
Nematopora bed of the early Trenton near Cannon Falls. Specimens

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 157

from the early Trenton of Trenton Falls, New York, and Montreal,
Canada, were described by Ulrich as Nematopora quadrata, but fur-

Fic. 77.—NEMATOPORA OVALIS. @, ZOARIUM, NATURAL SIZE, OF THE FORM DESCRIBED BY ULRICH AS NEMA-
TOPORA QUADRATA; b, PORTION OF THE SAME, X18; Cc, VERTICAL SECTION, X18; d, TRANSVERSE SECTION,
X50. LOWER PART OF THE TRENTON LIMESTONE, TRENTON FALLS, NEW YORK. ¢, FRAGMENT OF
NEMATOPORA OVALIS, NATURAL SIZE, AND X18, WITH FIVE ROWS OF ZOGCIA; f, ANOTHER FRAGMENT,
NATURALSIZE AND X18, WITH ONLYFOURROWS. LOWER PART OF THE TRENTON, CANNON FALLS, MINNE-
SOTA. (AFTER ULRICH.)

ther research on his part proved their identity with N. ovalis. Rus-
sian specimens have been found so far only in the Kuckers shale
(C2), Baron Toll’s estate, Esthonia (Cat. No. 57251, U.S.N.M.).
Represented in the col- ss,
lections of the British
Museum by a specimen
from the Kuckers shale,
Baron Toll’s estate.

NEMATOPORA FRAGILIS Ulrich.
Text fig. 78.

Nematopora fragilisUiRicH,
Geol. Surv. Illinois,
vol. 8, 1890, p. 646, pl.
29, figs. 10-10c.

5 = SIZE, SHOWING MODE OF BRANCHING; 0, PORTION OF THE
Zoarium of Mee slen SAME, X18; c, TRANSVERSE SECTION, X50; d, VERTICAL SEC-
der, dichotomously divid- TION, X18. GIRARDEAU LIMESTONE, RICHMOND GROUP,

ALEXANDER COUNTY, ILLINOIS. (AFTER ULRICH.)

ing branches about 0.35
mm. in diameter, with the zoccia arranged in six longitudinal
ranges not separated by aridge. Seven zocecia in 4 mm., measuring
lengthwise. Apertures ovate, channeled posteriorly with a faint

158 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

peristome around the sides and front margin, 0.08 mm. wide and 0.16

mm. in length.

Fragments of this characteristic American Richmond species are
not uncommon in the collections from the Lyckholm limestone. The
delicacy of their branches, as well as the characters noted above, will*
distinguish these from all associated bryozoans.

Occurrence.—Girardeau limestone division of the Richmond group,
Alexander County, Illinois; Lyckholm limestone (F1), Kertel, on
the island of Dago, Esthonia (Cat. No. 57252, U.S.N.M.).

British Museum, one specimen from the Lyckholm limestone, Ker-
tel, island of Dago.

NEMATOPORA LINEATA (Billings).
Text fig. 79.

Helopora lineata Bruines, Cat. Sil. Foss Anticosti, 1866, p. 36.
Nematopora lineata Utricu, Geol. Surv. Illinois, vol. 8, 1890, p. 646, pl. 29, figs.
THe.

Certain thin layers in the lower part of the Anticosti group on the
island of Anticosti, Gulf of St. Lawrence, are crowded with fragments
of arather robust species of Nematopora described by Billings as Helo-
pora lineata. Ulrich has figured the essential external and internal
features of the species, referring it to his genus Nematopora. Speci-
mens indistinguish-
able from this Ne-
matopora are con-
tained in the solid
limestone of the
Borkholm forma-
tion.

b

other species of the
genus, the branches
of Nematopora line-
ata are quite stout,

E ae averaging a milli-
Fic. 79.—NEMATOPORA LINEATA, @, FRAGMENT, NATURAL SIZE; 6b, SUR- ° :
FACE OF SAME, X18; ¢, VERTICAL SECTION, X18; d AND e, TWO TRANS- meter in diameter.
VERSE SECTIONS, X18; f, PORTION OF e, X50, SHOWING MINUTE AXIAL They are distinctly
CANALS AND WALL STRUCTURE. RICHMOND DIVISION OF ANTICOSTI h l . t
GROUP, ISLAND OF ANTICOSTI. (AFTER ULRICH.) exagonal In trans-

verse section on ac-
count of the zocecial arrangement in six rows separated by longitu-
dinal ridges. The lineate appearance given the branch by these
ridges is increased by the development of a second ridge, usually con-
necting the zocecia. Measuring lengthwise, three and one-half zocecia
occur in 2 mm.

Compared with .

ee

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 159

Occurrence.—Common in the Richmond equivalent of the Anticosti
eroup on the island of Anticosti; less abundant in the Borkholm
limestone (F2) at Borkholm, Esthonia (Cat. No. 57253, U.S.N.M.).

Typical specimens from Anticosti are in the collections of the
British Museum.

Genus GLAUCONOME Goldfuss.

Glauconome Goupruss, Petrefacta Germanie, 1826, p. 100.—LonspaLe, Murch-
ison’s Silurian System, 1839, p. 677.—SHRUBSOLE and Vinz, Quart. Journ.
Geol. Soc. London, vol. 40, 1884, p. 329.

Penniretepora D’ORBIGNY, Prodr. de Pal., vol. 1, 1850, p. 45.

~The Borkholm limestone contains two species of Bryozoa with
close relations to Nematopora but differing in having one side non-
celluliferous. One of these is identical with Billings’s Glauconome
strigosa, from the Anticosti group of Canada, while Wiman has
described a second as Glauconome plumula. Regarding the standing
of the name Glauconome, Lonsdale remarks as follows:

Goldfuss has described under the generic name of Glauconome five fossils, four of
which, according to De Blainville (Man. d’Actinologie, p. 454) and Milne-Edwards
(2nd Edit. Lamarck, t. ii, p. 193), belong to the genus Vincularia, previously estab-
lished by De France (Dict. Sc. Nat., tom. lviii, p. 214). The fifth species, common
at Dudley, possesses, however, characters essentially different from those of Vincu-
laria, and even to those assigned to Glauconome by Goldfuss. Instead of the stem
being impressed on all sides with rows of cells, it has them over only half the surface,
the other half being striated longitudinally. It is probable that the position of the
fossil in the matrix prevented that author from detecting the true characters of the
coral. For this fossil it has been thought right to retain Goldfuss’s name, but a modi-
fication in both the generic and specific characters has become necessary. Gen.
char.—Stem stony, thin, elongated, oval, branched; cells disposed longitudinally
and alternately in rows over one-half the surface, the other half striated longitudi-
nally. Nature of the covering and opening of the cells unknown.

Later work by Vine and Shrubsole led them to suggest that the
name Glauconome be retained for the G. disticha Lonsdale. In 1847
D’Orbigny in his Prodrome de Paleontologie proposed Penniretepora.
His work on the subject is quoted below:

Penniretepora d’Orb. 1847. Deuxrangéesdecellulesd’unseulcéte. Ensemble
penniforme, avec une tige et des rameaux libres latéraux.

Lonsdalei d’Orb. 1847. Glauconome disticha, Lonsdale, 1839. In Murch.
Silur. Syst., pl. 15, fig. 12d (mon Glauconome disticha Gold., 1830), Angle-
terre, Wenlock-rock.

To sum up, I believe Lonsdale, Vine, and Shrubsole to be correct
in recognizing Glauconome, for the following reasons. Goldfuss
specified no particular type for his genus. Lonsdale was justified,
therefore, according to the rules of nomenclature, in adopting G.
disticha, and in redefining the genus. Although Goldfuss did not
figure the noncelluliferous side of G. disticha, in fact, did not even

160 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

recognize it since his specimens were imbedded in the rock, his illus-
trations and those of Lonsdale are undoubtedly based upon the
same species. The new names Penniretepora and Penniretepora
lonsdalei of D’Orbigny are therefore superfluous.

Glauconome, as here recognized, seems to be an undoubted member
of the Arthrostylide, differing from all other genera of the family
in its continuous branching zoarium with the reverse side noncel-
luliferous. None of the many specimens of G. disticha and G. strigosa
before me shows any evidence of a basal articulation, so that it is
probable that the zoarium was attached at the lower end instead of

Fig. 80.—GLAUCONOME PLUMULA. @ TO d, FRAGMENTS OF FOUR ZOARIA. €, NONCELLULIFEROUS SIDE,

X10; f, CELLULIFEROUS FACE, X10; g AND h, TWO TRANSVERSE SECTIONS, X10. BORKHOLM DRIFT, OJLE _

MYR, ISLAND OF GOTHLAND. (AFTER WIMAN.)

jointed. With regard to the distribution of the apertures, Glauco-
nome bears the same relation to Nematopora that Arthrostylus has to
Helopora.

Genotype.—Glauconome disticha Goldfuss. Silurian of England

and Gothland.

GLAUCONOME PLUMULA Wiman.
Text fig. 80.

Glauconome plumula Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, No.
10, 1902, p. 181, pl. 6, figs. 17-24.

This is undoubtedly a typical species of Glauconome closely related
to the genotype. My material for study consists of a poorly pre-
served specimen from the Lyckholm limestone, but Wiman’s figures
clearly indicate the characters and relationship of his species. It
need only be compared with G. disticha from which it differs, so far
as I can judge, only in branching a trifle more regularly and more
frequently, and in having slightly smaller zoccia less regularly
arranged. In G. disticha the zoccial apertures are arranged in four
regular rows, two on each side of a conspicuous carina. Study of

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 161

well-preserved specimens of G. plumula may show a still closer
relationship, in fact possible identity with G. disticha.

Occurrence.—Drift, Ojle Myr, island of Gothland; Borkholm lime-
stone (2), at Borkholm, and Lyckholm limestone (F1), Kertel, on
the island of Dago, Esthonia (Cat. No. 57254, U.S.N.M.).

Fic. 81.—GLAUCONOME STRIGOSA. WIMAN’S FIGURES OF THIS SPECIES, DESCRIBED BY HIM AS ‘‘SPECIES
No. 1;” @ AND 6, TWO FRAGMENTS, NATURAL SIZE; Cc, VIEW, X10, OF THE CELLULIFEROUS FACE; d, SIDE
VIEW, X10, SHOWING THE STRIATED, NONCELLULIFEROUS SIDE AND AN ADJOINING ROW OF ZOGCIA; e,
TRANSVERSE SECTION, X10, ILLUSTRATING THE STRIATED BASAL SIDE AND FOUR ROWS OF ZOG@CIA OPENING
ON THE CELLULIFEROUS SIDE. BORKHOLM DRIFT, OJLE MyR, ISLAND OF GOTHLAND.

GLAUCONOME STRIGOSA (Billings).
Text fig. 81.

Helopora strigosa Bunuines, Cat. Sil. Foss. Anticosti, 1886, p. 37.

Nematopora strigosa Uricu, Geol. Surv. Illinois, vol. 8, 1890, p. 645.

Species No. 1, Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, No. 10, 1902,
p. 181, pl. 6, figs. 29-33.

A single well-preserved specimen of Glawconome from the Borkholm
limestone at Borkholm presents all of the characters seen in the
American form described by Billings as Helopora strigosa. The
American types have not yet been illustrated, but I am basing my
identification of the species mainly upon examples in the collection
of the United States National Museum which have been compared
directly with Billings’s described specimen. Wiman’s views of his
‘‘Species No. 1,” herewith reproduced, serve very well for the identi-
fication of the species. As seen from them, the zoarium is a narrow,
branched stem 0.5 mm. in diameter, with ovate zoccial apertures
arranged in four or five rows, and the remaining portion of the surface

162 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

noncelluliferous and finely striated. Measuring longitudinally, four
zocecia occur in 2 mm. In cross-section, the zoarium is rounded
polygonal in outline, as shown in figure 81 e. The zoecia are about
their own length apart longitudinally and the several rows are
separated by a poorly developed ridge.

The slender branches with one side noncelluliferous and striated,
and the rest of the surface celluliferous, are so distinct from all
associated bryozoans that comparisons are unnecessary.

Occurrence.—Abundant in the Richmond division of the Anticosti
group on the island of Anticosti, where it is associated with equally
numerous specimens of Nematopora lineata. Apparently rare in the
Borkholm limestone (F2) at Borkholm, Esthonia (Cat. No. 57255,
U.S.N.M.), where also it occurs with Nematopora lineata. Also in
the Borkholm drift, Ojle Myr, island of Gothland.

Family RHABDOMESONTID Vine.

Species of this family have hitherto not been recorded from strata
earlier than the Silurian, so that the occurrence of a new species of
Rhombopora, and at least one species of a new generic type in the
Middle Ordovician, is of considerable interest. The new genus is
peculiar in the development of a great number of mesopores, a fact
which will cause aslight change in the hitherto published diagnosis
of the family.

Genus RHOMBOPORA Meek.

Rhombopora M=Ek, Pal. Eastern Nebraska, 1872, p. 141.—ErHEeripGe, Ann. and
Mag. Nat. Hist., ser. 4, vol. 20, 1877, p. 36.—VinE, Proc. Yorkshire Geol.
Polyt. Soc., vol. 8, 1883, p. 105.—Utricu, Journ. Cincinnati Soc. Nat. Hist.,
vol. 7, 1884, p. 26.—VinE, Proc. Yorkshire Geol. and Polyt. Soc., vol. 9,
1885, p. 93.—Forrsts, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 71.—
WaacENn, Mem. Geol. Surv. India, Paleontologia Indica, ser. 13, vol. 1,
1888, p. 963.—MitteR, North Amer. Geol. and Pal. 1889, p. 321.—URIcu,
Geol. Surv. Ill., vol. 8, 1890, pp. 402, 647; Zittel’s Textbook of Paleontology
(Eng. ed.), 1896, p. 281.—Simeson, Fourteenth Ann. Rep. State Geologist New
York for the year 1894, 1897, p. 550.—Grasavu, Bull. Buffalo Soc. Nat. Hist.,
vol. 6, 1899, p. 164.—NickLEs and Basstrr, Bull. 173, U. 8. Geol. Surv.,
1900, p. 43.

In this genus the zoarium consists of solid ramose slender branches
with the zocecial tubes in the vestibular region, thick-walled and
with numerous strong acanthopores and smaller spines. The aper-
tures are generally arranged in distinct longitudinal or diagonal lines.
The external aperture is oval or circular, and is usually situated at
the bottom of a rhombic or hexagonal sloping area.

The following new species is remarkably like the Carboniferous
type of the genus, in fact, so far as can be determined from fossil
forms, is distinguished only by such minor characters as slight

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 163

differences in the size and shape of the zocecia. Still it is believed
that this close similarity does not indicate a correspondingly close
relationship and that Rhombopora esthoniz is simply an early expres-
sion of the general generic type which did not endure.

Fig. 82.—RHOMBOPORA ESTHONIE. @, FRAGMENT OF ZOARIUM, NATURAL SIZE; 6, TANGENTIAL SECTION,
X20; c, PORTION OF ANOTHER TANGENTIAL SECTION, X20, CUTTING A MACULA; d, VERTICAL SECTION,
X20; €, TRANSVERSE SECTION, X20. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

Genotype.—Rhombopora lepidodendroides Meek. Carboniferous
(Upper Pennsylvanian) of the United States.

RHOMBOPORA ESTHONIZ, new species.

Text fig. 82.

Zoarium a smooth, cylindrical stem, 2 to 3 mm. in diameter,
branching dichotomously at intervals of 15 mm. more or less. Zoo-
cial apertures ovate, averaging 0.20 mm. in length and 0.11 mm. in
width, arranged in irregular series, with, however, a tendency to
longitudinal rows. Measuring longitudinally, four to five zocecia in 2

164 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

mm., transversely six to seven rows occur in the same distance. Inter-

zocecial spaces as wide as the apertures and having a carina which -

carries numerous small spines or acanthopores. Sloping areas about
the apertures of variable shape, but usually polygonal with a ten-
dency to hexagonal.

All of the features believed to be seen in thin sections are shown in _

figure 82 6 to e. Both transverse and vertical sections show that
the immature region is composed of thin-walled zoccia with a few
complete diaphragms. In the mature zone the walls thicken greatly
and the usual cryptostomatous cell is developed. Tangential sec-
tions indicate the oval zocecia with thick interspaces in which rows of
small pores indicate the course of the surface carine. The maculze
are composed entirely of such interzoccial tissue pierced by pores
as shown in fig. 82 ¢.

Occurrence—Somewhat uncommon in the Jewe limestone (D1),
Baron Toll’s estate, Esthonia.

Holotype.—Cat. No. 57256, U.S.N.M.

One specimen and a thin section of the type are in the collections of
the British Museum.

NEMATOTRYPA, new genus.

Zoarium of slender, solid branches composed of long, tubular
zocecia diverging obliquely from a central, thread-like axis. Surface
smooth with oval zoewcia arranged in rather regular, longitudinal
rows. Interzocecial space filled by numerous small mesopores open
at the surface. Hemisepta and acanthopores or spines as in other
members of the family._

Genotype.— Nematotrypa gracilis, new species. Middle Ordovician
of Russia and Sweden.

The name which has been chosen for this genus has reference to
the thread-like central axis from which the zoccia proceed to open
at the surface as so many perforations or apertures. The name will
also in part recall Nematazis, another genus of the Rhabdomeson-
tidze, which is believed to be related. ‘The internal arrangement of
the zocecia is much the same in the two genera, but in Nemataxis the
interspaces are solid instead of being occupied by open mesopores
as in Nematotrypa.

The species upon which Nematotrypa is based is a very abundant
fossil in several of the Middle Ordovician formations of Baltic Russia
and Sweden. Fragments from the Lyckholm limestone of the island
of Dago, too small for the recognition and description of another
form, probably represent another species.

Oe,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 165

NEMATOTRYPA GRACILIS, new species.

Text fig. 83.

Zoarium, a cylindrical stem varying in diameter from 0.5 to 1.5
mm., occasionally branching dichotomously. Basal portion of zoa-
rium unknown, but probably attached parasitically as in Rhombo-
pora. Surface of zoarium smooth but with distinct macule of small
mesopores at regular intervals. In young specimens the zoccia are
regularly oval and are arranged in distinct longitudinal rows sepa-
rated by rows of small, elongated mesopores. With age the longi-
tudinal arrangement of both sets of cells becomes less evident and
the zocecial apertures are less regularly oval, while the mesopores

Lea 6 Gy
SH
(4
Leta _ 6 fm

Ce:
é Nee PINS)

Fic. 83.—NEMATOTRYPA GRACILIS. @, FRAGMENT OF ZOARIUM, NATURAL SIZE; 0, TANGENTIAL SECTION,
X20; c, PORTION OF THE SAME, X40; d, TANGENTIAL SECTION, X50, THROUGH A MACULA AND ADJOINING
ZOGCIA; €, VERTICAL SECTION, 20; f, TRANSVERSE SECTION, X20, SHOWING GROWTH FROM CENTRAL
AXIS. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

assume a polygonal shape. The usual zocecium is 0.16 mm. long
and not more than 0.10 mm. wide, with eight or nine in 2 mm., meas-
uring longitudinally. The mesopores are exceptionally small, thin-
walled, and in practically every case isolate the zoccia. In the
older zoaria minute granules occur on the cell walls, particularly in
the macular areas.

It is difficult to prepare vertical sections showing the character-
istic central thread-like axis from which the zoccial tubes proceed,
but transverse sections such as shown in figure 83 f exhibit this feature
clearly. The noteworthy features of vertical sections are the thin-
walled character of the zocecia in the immature region, the develop-
ment of an unusual number of small tabulated mesopores in the
mature zone, and the occurrence of several distinct sets of inferior

166 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

and superior hemisepta in the same region of the zocecia. Views of a
tangential section under several magnifications are given in figures
83 6 and c, while in figure 83 d the structure of a macular area with
its neighboring zoccia is shown. The latter section was prepared
from an old example in which the small pores or granules are well
developed. Here also the mesopores forming the macular area have
been partially closed by a dense tissue.

Externally Nematotrypa gracilis can ‘readily be Puen from
other Ordovician bryozoans by its slender branches of small, oval
zocecia, isolated by exceedingly minute and numerous thin-walled
angular mesopores. The internal features are too different to require
comment.

Occurrence-—A common fossil of the Kuckers shale (C2), Baron
Toll’s estate, Esthonia, where the types were found. Other forma-
tions and localities are the Jewe limestone (D1), Baron Toll’s estate,
the Echinospherites limestone (C1), 4 miles east of Reval, ard the
Chasmops li) estone, near Bédahamn, on the island of Oeland.

Cotypes.—Cat. iMag. 57258, U.S.N. M.

Specimens and thin sections from the Kuckers shale, Baron Toll’s
estate, and from th Chasmops limestone, island of Oeland, are in
the eral Museum.

Family RHINOPORIDS Ulrich.

A single genus and species of this rather unique family is present
in the Russian faunas under study. In a former publication * I have
pointed out the following characters for the family, which may in
some respects be considered one of the simplest divisions of the
Cryptostomata.

Zoarium variable in form; zocecia prone along the basal membrane, simple, oblong,

or rhomboidal; vestibules direct, hemisepta wanting or almost so; front of zocecia
below vestibule commonly strengthened with solid or vesicular tissue.

Genus LICHENALIA Hall.

Lichenalia Hatz, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 401; Nat. Hist. New
York, Pal., vol. 2, 1852, p. 171.—Basster, Bull. 173, U. 8S. Geol. Surv., 1900,
pp. 54, 299; Bull. 292, U.S. Geol. Surv., 1906, p. 60.

In the search for bryozoans in the solid limestones of the Borkholm
formation numerous thin, epithecated, subcircular expansions were
encountered in a more or less fragmentary state while breaking the
rock. These at once recalled the very similar expansions occurring
in the Niagaran (Rochester) shales of western New York and desig-
nated by- Hall as Lichenalia concentrica. Upon the preparation of
numerous thin sections and a study of microscopic characters this
surmise was found to be correct, for no differences of any specific

1 The Bryozoan Fauna of the Rochester Shales, Bull. 292, U. S. Geol. Surv., 1906, p. 59.

—eE——EEE

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 167

value could be found between these Borkholm specimens and those
from the Niagaran in America.

Numerous epithecated bryozoans from various localities have been
registered as Lichenalia concentrica, because Hall’s description and

a b
aa ey Red ie

©

‘aed

Fig. 84.—LICHENALIA CONCENTRICA. @, EPITHECAL SIDE OF A FRAGMENTARY SPECIMEN. BORKHOLM
LIMESTONE, BORKHOLM, ESTHONIA ; 6, PORTION OF A TANGENTIAL SECTION, X20, CUTTING THE HIGH
ANTERIOR END OF THE PERISTOME AND A FEW OF THE CONNECTING WALLS; c, A TANGENTIAL SECTION,
X20, PASSING THROUGH A LOWER PORTION OF THE ZOARIUM THAN IN c. THE LOWER PORTION OF THE
FIGURE ILLUSTRATES THE ZOG@CIA AND MESOPORE-LIKE STRUCTURE OF THE MATURE REGION, THE MIDDLE
PORTION, THE OBLONG OR RECTANGULAR SHAPE OF THE ZOGCIA IN THE IMMATURE ZONE, WHILE IN THE
UPPER PART OF THE DRAWING ARE SHOWN PORTIONS OF THE CONCENTRIC RINGS OF THE EPITHECA; d, A
TANGENTIAL SECTION, X6, PASSING CLOSE TO THE SURFACE OF THE ZOARIUM AND CUTTING ONE OF THE
MEANDERING CANALS; €, A PORTION OF A TANGENTIAL SECTION, X20, ILLUSTRATING THE NATURE OF THE
WALLS OF THE MESOPORE SPACES; f, A VERTICALSECTION, X20, ILLUSTRATING THE FOLLOWING CHARACTERS:
2, THE ZOGCIA; Cc, ONE OF THE CANALS, COVERED ABOVE; wb, UNDULATING BASE OF ZOARIUM; Ww, WALLS
FORMING THE MESOPORE-LIKE SPACES; ~, THE EXTREMELY HIGH POSTERIOR PORTION OF THE PERISTOME;
a, THE LOW ANTERIOR PORTION OF THE PERISTOME; AND p’, A POSTERIOR PORTION OF THE PERISTOME
CUT OBLIQUELY; g, A MORE DIAGRAMMATIC VERTICAL SECTION, X20, SHOWING ESPECIALLY THE LOW AND
HIGH PORTIONS OF THE PERISTOME AND THE WALLS OF THE INTERZOG@CIAL SPACES. ROCHESTER SHALE,
Lockport, NEw YORK. (AFTER BASSLER.) ;

figures applied only to the basal portion of these subcircular expan-

sions and gave no idea at all of the surface or internal characters.

More detailed characters of the genus were not published until 1906,'
1 Bull. 292, U.S. Geol. Surv., 1906.

168 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

when I had the opportunity of studying Hall’s original types and of
determining the generic characters to be as follows: Zoarium a sub-
circular, unilaminar expansion; zoccia prostrate; elongate-subrhom-
boidal, with erect, subtubular vestibules; apertures rounded with

peristome much elevated on the posterior side; interspaces depressed; ~

surface traversed by slender, bifurcating ridges which thin sections
show to be in reality closed canals.
This peculiar type of structure is represented by a single species,
which, however, from its specific peculiarities is easily recognized.
Genotype.—Lichenalia concentrica Hall. Silurian of North America
and Russia.
LICHENALIA CONCENTRICA Hall.

Text fig. 84.

Lichenalia concentrica Hatt, Nat. Hist. New York, Pal., vol. 2, 1852, p. 171, pl.
40F, figs. 5a-g.—BasstER, Bull. 292, U. 8. Geol. Surv., 1906, p. 61, pl. 22,
figs. 1-6; pl. 26, figs. 7-10.

As this is the genotype and only valid species of the genus, the
specific characters are as given above. The thin, unilaminate zoaria,
large zocecia (averaging 0.5 mm. in their longer diameter), and the
meandering surface canals, are characters making the species easily
recognized. None of the Borkholm specimens shows any portion
but the epithecated base, because in breaking the limestone this
portion, being smooth, parts most readily. These epithecated
expansions differ in nowise from the same portion of other explanate
bryozoans, so that specimens must be either sectioned or smoothed
down and etched to get a view of the internal and surface characters
before they can be recognized specifically. Figure 84a represents
the usual fragmentary specimen characteristic of the Borkholm, while
figures 846 to g illustrate the internal structure of American speci-
mens in some detail. The microscopic structure is so unusual that
there is little danger of misidentifying the species.

Occurrence.—A characteristic species of the early Niagaran rocks
in America; common in the Borkholm limestone (F2) at Borkholm,
Esthonia.

Plesiotype—Cat. No. 57261, U.S.N.M.

Represented in the collections of the British Museum by speci-
mens from the Borkholm limestone, Borkholm.

Family PHYLLOPORINID Utrich.

Zoarium branching; branches free or anastomosing, celluliferous
on one side only, the other side striated; zocecia more or less tubular,
often with diaphragms; hemisepta wanting.

Both of the two genera referred to this family are represented in
the Russian and Swedish deposits.

EARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 169

Genus CHASMATOPORA BEichwvald.

Chasmatopora EricHwatp, Lethsea Rossica, vol. 1, 1860, p. 370.

Phylloporina (Ulrich) Forrsts#, Bull. Sci. Lab. Denison University, vol. 2, 1887,
p. 150.—Utricu, Geol. Surv. Lllinois, vol. 8, 1890, pp. 399, 639; Geol. and
Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 208; Zittel’s Textbook
of Paleontology (Eng. ed.), 1896, p. 283.—NickLes and Basster, Bull. 173,
U.S. Geol. Surv., 1900, p. 37.—Basstzr, Bull. 292, U. S. Geol. Surv., 1906,
p. 48.

Subretepora D’OrBIGNY, Prodr. de Pal., vol. 1, 1850, p. 22.—Mitter, North
Amer. Geol. and Pal., 1889, p. 326.

Intricaria Haut, Nat. Hist. New York, Pal., vol. 1, 1847, p. 77.—Muither and
Dyer, Contr. Pal., No. 2, 1878, p. 7.

The generic type to which this name was first applied was best
described under the name of Phylloporina by Ulrich, but it seems, to
me that the earlier designation Chasmatopora has the best right to rec-
ognition. The facts in the case are as follows:

In 1860 Hichwald proposed the new genus Chasmatopora, giving a
fair description for that date, and basing the genus upon a single
species, C. tenella, which he compared with Hall’s Retepora angulata,
from the Clinton group, of NewYork. His figure of C. tenella, although
far from present standards, is sufficient to show that his type-specimen
was an angular meshed form closely related to Hall’s species. Col-
lections from the Borkholm limestone show numerous examples of
such a species, and I have little doubt that this is the form Kichwald
had in mind.

D’Orbigny’s Subretepora was based upon the well-known, widely
distributed form /ntricaria reticulata Hall, but the author of this
generic name relied upon Hall’s faulty descriptions and figures for
his definition. The result was that Subretepora was incorrectly
defined, and for that reason Ulrich proposed the new name Phyji-
loporina.

As pointed out by Ulrich, several distinct types of structure are
included in Phylloporina. It is therefore probable that with more
study both Phylloporina and Chasmatopora may be recognized.

In Chasmatopora the zoarium is of irregularly anastomosing
branches with two to eight rows of apertures on one side and the
other side noncelluliferous but striated.

Genotype—Chasmatopora tenella Eichwald. Earliest Silurian of
Russia.

CHASMATOPORA TENELLA (Eichwald).
Text fig. 85.

Retepora tenella E1cHwaup, Schichtensyst. von Esthland, p. 207; Urwelt Russ-
lands, vol. 2, 1842, p. 47, pl. 1, fig. 7.

Chasmatopora oman Deere Bull. de la Soc. Nat. Moscou, 1855, No. 4, p. 460;
Lethzea Rossica, vol. 1, 1860, p. 371.

Cir. Retepora angulata sie, Nat. Hist. New York, Pal., vol. 2, 1852, p. 49, pl.
19, figs. 3a-h.

170 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

As indicated under the generic remarks, C. tenella is based upon a
very common Borkholm limestone species quite similar to Hall’s
Retepora angulata. This similarity is so great that had the Russian
specimens been derived from the American Clinton deposits holding
Hall’s species they would probably have been identified as the
same. However, until a detailed study of all the species of Chas-
matopora and related genera has been made, I prefer to regard C.
tenella as distinct, recognizing, as did Hichwald, this great similarity.

The fenestrules of C. tenella are quite regularly
angular in outline and average 2.5 mm. in length
by 1.0 mm. in width. Eichwald’s figure (fig. 85)
shows this angularity and also indicates the number
; of zoccial apertures. The noncelluliferous side is
Fie. 85.—Caasuaro- longitudinally striated.

PORA TENELLA. § Qccurrence.—Hichwald registers this species from
CELLULIFEROUS 5 P
race tEntarcrn, the island of Dago, and from Baltischport and
i Stee faites Spitham, Esthonia. Specimens are abundant in the
Barnscuront, Es Borkholm limestone (F2) at Borkholm, Esthonia
ans (Cat. No. 57263, U.S.N.M.).
The collections of the British Museum contain
specimens and thin sections from the Borkholm limestone, Borkholm.

CHASMATOPORA RETICULATA (Hall).
Text fig. 86.

Intricaria? reticulata Haut, Nat. Hist. New York, Pal., vol. 1, 1847, p. 77, pl. 26,
figs. 8 a-c.

Subretepora reticulata MittER, North Amer. Geol. and Pal., 1889, p. 326, fig. 524.

Phylloporina reticulata Utricn, Geol. Surv. Illinois, vol. 8, 1890, pp. 332, 639, pl.
58, figs. 2, 2a; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
210, pl. 4, figs. 8-15.

A number of specimens indistinguishable from the types of this
interesting bryozoan have been found in the Wassalem beds at
Uxnorm where they are associated with numerous other American
Black River species. The following description and text figure,
copied from Ulrich, will serve equally for the recognition of the
Russian specimens:

Specimens as seen, consisting of small, flat or undulating, reticulate expansions,
being in each case evidently fragments of a depressed, funnel-shaped zoarium, prob-
ably not exceeding 5 cm. in diameter. Branches rounded in section, 0.2 to 0.3 mm.
in diameter, inosculating at unusually frequent and regular intervals. Fenestrules
somewhat elongate, about as wide as the branches, subrhomboidal in shape in the
more regularly constructed fragments; their number in a given space is fairly constant,
the extremes noticed in 1 cm. being ten and twelve. Reverse of branches convex,
finely striated lengthwise.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 171]

Obverse strongly convex, with three rather irregular rows of zocecia, their apertures
subcircular, with a distinct peristome, about 0.1 mm. in diameter, eight or nine in
2mm. Acanthopores abundant, irregularly distributed, rather large, especially so
in the earliest forms of the species. Interspaces slightly concave, occasionally faintly
pitted and striated.

In tangential sections the zocecia are rather short, with a row on each side directed
obliquely outward, and one series between them. The latter are wedge-shaped, and
in deep sections appear as a more or less narrow central space. Diaphragms, one in
each tube, have been observed.

Occurrence—The American specimens are from the Black River
and early Trenton, at various localities in New York, Vermont,

\

ahs

id i

c s

Fic. 86.—CHASMATOPORA RETICULATA. ULRICH’S FIGURES OF PHYLLOPORINA RETICULATA, @ AND b, TWO FRAGMENTS,
NATURAL SIZE, EXPOSING THE REVERSE SIDE; C, PORTION OF Db, X9; d, PORTION OF a, X9, SHOWING BROADER BRANCHES;
é, CELLULIFEROUS SIDE OF A FRAGMENT, X18. BLACK RIVER (DECORAH) SHALES, MINNEAPOLIS, MINNESOTA.

Minnesota, and Canada. Not uncommon in the Wassalem beds
(D3) at Uxnorm, Esthonia (Cat. No. 57262, U.S.N.M.).

Represented in the collections of the British Museum by specimens
from American localities.

CHASMATOPORA FURCATA (Eichwald).
Plate 12; text fig. 87.

Polypora furcata ErcHwapD, Bull. Soc. Nat. Moscou, No. 1, 1854, p. 89; No. 4,
1855, p. 451; Lethzea Rossica, vol. 1, 1860, p. 378, pl. 23, fig. lla, 6.

Eichwald’s figures of this species show its characters in sufficient
detail to cause its recognition easy. Its diagnostic features are,
first, the large size of the fenestrules, and, second, the conspicuous

92602°—Bull. 77—11——13

172 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

grano-lineate ornament of the noncelluliferous side. The other
Russian species of the genus are too different to require comparison,
but in America certain undescribed Black River forms are closely
selated. As shown on plate 12, the zoarium is a flabelliform expan-
tion consisting of slender inosculating branches averaging 0.3 mm.
inwidth. Thefenestrules
are large and elongate,
generally two or three
times longer than wide.
Measuring _ lengthwise,
four fenestrules occur in
1 centimeter.
Occurrence.—Hich-
wald’s types were ob-
tained from ‘‘le schiste
inflammable argileux”’ at
Erras. The species is
quite abundant in the
Kuckers shale (C2), Baron
Toll’s estate, near Jewe,
Esthonia.
Plesiotype.—Cat. No.

Fic. 87.—CHASMATOPORA FURCATA. EICHWALD’S VIEWS OF 57264, U.S.N.M.
POLYPORA FURCATA. @, ZOARIUM, NATURAL SIZE; 0, AN 2
ENLARGEMENT OF THE NONPORIFEROUS SIDE, SHOWING DIS- The collections of the
TINCT ROWS OF PAPILLH; c, CELLULIFEROUS FACE ENLARGED. British Museum contain
“SCHISTE INFLAMMABLE ARGILEUX,” ERRAS, ESTHONIA.

specimens and thin sec-
tions from the Kuckers shale (C2), Baron Toll’s estate.

Genus PSEUDOHORNERA Roemer.

Pseudohornera Rormer, Leth. geog., Leth Pal., vol. 1, Atlas, 1876, expl. pl.
12.—BasstER, Bull. 292, U.S. Geol. Surv., 1906, p. 49.

Drymotrypa Utricx, Geol. Surv. Illinois, vol. 8, 1890, p. 309.—Mmtzr, North.
Amer. Geol. and Pal., First Appendix, 1892, p. 684.—_NickiEs and BasstEr,
Bull. 173, U.S. Geol. Surv., 1900, p. 235.

Thamnocella Stupson, Fourteenth Ann. Rep. State Geol. New York for 1894,
1897, p. 525.

This genus is best known under the name of Drymotrypa, to which
practically all of its species have been referred, but Pseudohornera
must be retained since it, as well as Drymotrypa, was founded upon
the same species, Hall’s Retepora diffusa. |

The zoarium in Pseudohornera is of dichotomously dividing branches
celluliferous on one side and longitudinally striated on the reverse.
The zocecia are in several ranges and spring from a thin double plate,
beneath which is a number of vesicles; the vestibules expand from
the orifice to the angular apertures.

Genotype.—Retepora diffusa Hall. Niagaran of New York and
Canada.

EHARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 173
PSEUDOHORNERA BIFIDA (Eichwald).
Plate 8, fig. 5; plate 12; text figs. 88, 89, 90.

Thamniscus bifidus EKicnwaup, Lethza Rossica, vol. 1, 1860, p. 386, pl. 23, fig.
17 a, 0.

Eichwald’s figures of this species, shown in text figure 88, are
scarcely enough to make its identification certain, but the fact
that he records his type-specimens
from Erras, Esthonia, and tha* he
compares the species with Hall’s Rete-
pora (now Pseudohornera) diff , led
me to regard my conception of the
form as correct. From the various fig-
ures given here in the text and on the
plate, there should be little difficulty in
recognizing Pseudohornera bifida. Most
of the specimens are imbedded in the
rock and show only the noncel-

3 Fig. 88.—PSEUDOHORNERA BIFIDA.
luliferous side, but one example was — gicnwaty’s vmws or THAmNiscus
found exhibiting the celluliferous sur- ®2™US-_@ AND}, ZOARIUM, NATURAL
face in a good state of preservation. pee per ee eee
Peale wem@ lw itllls) eels ayapresentedg.on =NeSEGHR) Chu uncs A Oro
plate 8. CERATITES,’’ ERRAS, ESTHONIA.

The rather regularly bifu~cating branches, the fine, grano-lineate
ornamentation of the noncelluliferous side and the rather numerous

Fic. 89.—PSEUDOHORNERA BIFIDA. @, TANGENTIAL SECTION, X20, OF AN OLD EXAMPLE SHOWING THICK-
WALLED, ANGULAR ZOGCIA; 6, VERTICAL SECTION, X20, EXHIBITING THE THICK, SOLID, NONPORITEROUS
SIDE PIERCED BY MINUTE TUBULI, AND THE SHAPE OF THE ZOGCIA; c, TRANSVERSE SECTION, X20. WAS-
SALEM BEDS (D3), UXNORM, ESTHONIA.

rows of longitudinally arranged zocecia on the celluliferous a are
characteristic of the species.

Occurrence —Eichwald records his types from the Ordovician at
Erras, Esthonia. Localities represented in the United States Na-

174 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

tional Museum’s collection are the Kuckers shale (C2), Baron Toll’s
estate, near Jewe; the Wassalem beds (D3), at Uxnorm; and the
Wesenberg limestone (EH) at Wesen-
berg, Esthonia.

Plesiotypes.—Cat. Nos. 57265, 57266,
57267, U.S.N.M.

Specimens from the Wassalem beds
(D3), Uxnorm, and the Kuckers shale
(C2), Baron Toll’s estate, are in the
collection of the British Museum.

PSEUDOHORNERA OROSA (Wiman).
Text g. 91:

Thamniscus orosus WIMAN, Bull. Geol. Inst.
Univ. Upsala, vol. 5, pt. 2, 1902, p. 181,
pl. 6, figs. 8-11.

( This species is known to me only
iG OL _PSEInGHORNEEA BINA: aan trom Wittan s description ald nzumes,
ORDINARY SPECIMEN, NATURAL sZE;b, thelatterbeigherereproduced. Judg-
NONCELLULIFEROUS SIDE OF A LARGER, 6 . o
MORE COMPLETE ZOARIUM, X2; ¢, sux. img from these, his Thamniscus orosus
FACE OF SAME, X4, KUCKERS SHALE jg g typical Pseudohornera, differing
(C2), BARON TOLL’s ESTATE, ESTHONIA. f Mi: Soe
from other species of the genus in its
frequently bifurcating zoarium, in the presence of large oval but
few apertures on the celluliferous side, and the distinct crest dividmg

the noncelluliferous side longitudinally.

a

(ane

FIG. 91.—PsEUDOHORNERA OROSA. WIMAN’S VIEWS OF HIS SPECIES THAMNISCUS OROSUS; @ AND 6, TWO
VIEWS, NATURAL SIZE, OF THE MANY-BRANCHED ZOARIUM; c, NONCELLULIFEROUS SIDE OF A SPECI-
MEN, X10; d, CELLULIFEROUS SURFACE, X10. BORKHOLM DRIFT, OJLE MYER, ISLAND OF GOTHLAND.

Occurrence.—Drift of the Borkholm limestone at Ojle Myr, island
of Gothland.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 175

Family FENESTELLID King.

But a single species of this prolific group of post-Ordovician Paleo-
zoic Bryozoa has been recorded from the Russian strata under study.
This is a species of the genus Fenestella which Eichwald has recorded
from the dolomitic limestone at Borkholm. In America the corre-
sponding strata have also afforded a single representative of the same

genus.
Genus FENESTELLA Lonsdale.

Fenestella LoONSDALE, Murchison’s Silurian System, 1839, p. 677.—EIcHWALD,
Lethza Rossica, vol. 1, 1860, p. 356.—SHRUBSOLE, Quart. Journ. Geol. Soc.
London, vol. 37, 1881, p. 179.—Utricu, Journ. Cincianati Soc. Nat. Hist.,
vol. 5, 1882, p. 150.—Haut and Simpson, Nat. Hist. New York, Pal., vol. 6,
1887, p. xxii—U.ricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 395, 534.—
Pocta, Syst. Sil. Centre Boheme, vol. 8, pt. 1, 1894, p. 40.—Uxricu, Zittel’s
Textbook Paleontology (Eng. ed.), 1896, p. 281.—Srupson, Fourteenth Ann.
Rep. State Geologist of New
York, for the year 1894, 1897,
p. 500.—NickLEs and Bas-
SLER, Bull. 173, U. S. Geol.
Surv., 1900, pp. 37, 244.—
Conpra, Nebraska Geol. “ey
Surv., vol. 2, pt. 1, 1903, p.
49.—Hennia, Archiv fur
Zool., K. Sven. Vet.-Akad.
Stockholm, vol. 3, No. 10,
1906, p. 1.

Fenestrella (error) D’OrsIGNY,
Prodr. de Pal., vol. 1, 1850,
p. 44.

Actinostroma YOUNG and YOUNG,
Quart. Journ. Geol. Soc. Lon-
don, vol. 30, 1874, p. 681.— iG. 92.—FENESTELLA STRIOLATA. a, ZOARIUM, NAT-
VINE, Proc. Yorkshire Geol. URAL SIZE; 6, NONPORIFEROUS SIDE ENLARGED; Cc,

SMALL PORTION OF PORIFEROUS SIDE, ENLARGED.
Polyt. Soc., vol. 9, 1885, p. 84. EARLY SILURIAN OF BALTIC RussIA. (AFTER EICH-

Flabelliporina Stupson, Thir- WALD.)
teenth Ann. Rep. State Geol.

New York for the year 1893, 1895, pp. 703, 724; Forty-seventh Ann. Rep.
New York State Mus., 1895, pp. 897, 918; Fourteenth Ann. Rep. State
Geologist New York for the year 1894, 1897, p. 521.

Zoarium flabellate or funnel shaped, celluliferous on the inner side;
branches generally straight, sometimes flexuous, connected at regular
intervals by dissepiments; apertures in two rows, separated by a
plain or tuberculated median keel.

Genotype.—Gorgonia antiqua McCoy. Accepted genotype /’. plebera
McCoy. Carboniferous of Europe.

VT Smee,

‘
Coase
urea

FENESTELLA STRIOLATA Eichwald.
Text fig. 92.
Fenestella striolata E1cowatp, Lethzea Rossica, vol. 1, 1860, p. 357, pl. 23, figs. 2a—c.

No specimens of this species have come to light in the collections
I have studied, but as Eichwald registers the species from Borkholm

176 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

in rocks most probably of Borkholm age, I have introduced the
species as a member of this fauna. As will be seen from the accom-
panying figure, F’. striolata is quite a typical Fenestella, differing but
little from a number of middle Silurian forms which might be men-
tioned. Indeed, it is possible that Eichwald’s figured type was
derived from younger rocks than the Borkholm limestone, since he
also registers the species from ‘‘le calcaire siliceux 4 Pentameres de
Talkhof en Livonie.” However this may be, I feel reasonably cer-
tain that the genus Fenestella in Europe begins in the Lyckholm or
Borkholm limestone, and for the present will recognize F. striolata
as a Borkholm species. As the Borkholm fauna contains so many
species in common with the Richmond group of North America,
which holds a neat Fenestella described by Whitfield as F. granulosa,
it is possible that Fenestella striolata has more relationship with the
American form than at present supposed.

Occurrence.—Silurian at Talkhof in Livonia, and at Borkholm,
Esthonia.

Order TREPOSTOMATA Ulrich.

Trepostomatous Bryozoa usually form so large a part of the col-
lections from American Ordovician horizons that, in number of
specimens at least, species of this order seem to make up the greater
part of a fauna. This is equally true for the various Baltic Ordo-
vician formations, indeed, certain limestone layers, such as those in
the Wassalem beds (D3), are literally one mass of ramose and other
bryozoans. As will be seen from the following pages, a fairly large
fauna of Trepostomata has been determined, but I am confident that
careful collecting with the Bryozoa particularly in mind will bring to
light many more species. The Trepostomata, which include nearly
all of the forms classed frequently under the general term ‘‘monti-
culiporoids,” have been the occasion of some discussion with reference
to their systematic position. Without entering into detail at the
present time, I still believe that all of the evidence favors their posi-

tion in the classification as a well-defined order of Bryozoa rather

than an aberrant division of the Anthozoa.

The division Trepostomata was established by Ulrich as a suborder
to include the majority of the Paleozoic Bryozoa. The principal
peculiarity of the division, now ranked as an order, was the fact that
at a certain pomt in the course of the tubes to the surface they change
their character entirely. This change occurs at the beginning of the
peripheral or mature zone of the zoarium and consists of the develop-
ment of mesopores, acanthopores, more numerous diaphragms,
opercula, and similar structures of the more mature zooid. In the
axial or immature portion of the tubes the walls are simple, thin,
and prismatic, with diaphragms few or wanting. The occurrence of

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 177

clusters of mesopores, or of cells larger than the average, at regular
intervals among the zoccia is another characteristic of the order,
although this feature is not confined exclusively to the Trepostomata.

Although under the original definition of the Trepostomata the
change in the character of the zocecial tubes as they pass from the
simple immature stage to the more highly organized mature zone was
the most distinctive character, it must be remembered that the
Paleozoic Ceramoporide and Fistuliporide and the more recent
Cerioporide have this same feature. In the latter families other
features, particularly their minutely porous wall structure, ally them
more closely to the Cyclostomata.

Ulrich and Bassler, in their ‘‘ Revision of the Paleozoic Bryozoa,”’ !
have proposed two divisions of the Trepostomata based upon the
minute structure of the walls separatmg adjoming zooids. Of the
seven families now recognized under the Trepostomata, four have
the calcareous investment of adjoinmg zoccia amalgamated together
so that one wall can not be distinguished from its neighbor. In the
remaining three families the walls retain their duplex character, and
when the zocecia are adjacent their boundaries are marked by a dark,
divisional line. This line in all probability represents the fossilized
remains of animal matter which filled this space during the life of the
organism. Occasionally this narrow, intervening area is occupied
by a light-colored tissue, and in this case the outer boundaries of the
walls of each zocecium can be seen. In certain genera of both divi-
sions the amalgamation or the distinct character of the walls is difficult
to determine, especially when mesopores are numerous, but if the
zoccia are in actual centact there is little trouble in deciding the
position of the particular form under study.

Following is a classification of the Ordovician and early Silurian
genera, with the genera common to the American and Baltic deposits
marked by an asterisk, and those restricted to the latter by a double
asterisk:

Division AMALGAMATA Ulrich and Bassler.

Trepostomata in which the boundaries of adjacent zocecia are
obscured by the more or less complete amalgamation of their walls:

Family MONTICULIPORID Nicholson. (emended Ulrich).

* Monticulipora D’ Orbigny. * Homotrypella Ulrich.
*Orbignyella Ulrich and Bassler. §_Prasopora Nicholson and Ethe-
Atactoporella Ulrich. ridge.
Peronopora Nicholson. * Mesotrypa Ulrich.
*Homotrypa Ulrich. Aspidopora Ulrich.

1 Smithsonian Miscellaneous Collections, vol. 47, 1904, pp. 15-55.

178 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.
Family HETEROTRYPIDA Ulrich.

Heterotrypa Nicholson. Petigopora Ulrich.
*Dekayella Ulrich. *Leptotrypa Ulrich.
Cyphotrypa Ulrich and Bassler. Atactopora Ulrich.
Dekayia Edwards and Haime. *Stigmatella Ulrich and Bassler.

Family CONSTELLARIID Ulrich.

*Constellaria Dana. Idiotrypa Ulrich.
*Stellipora Hall. *Dianulates Kichwald.
* Nicholsonella Ulrich.

Family BATOSTOMELLIDZ Ulrich.

*Bythopora Miller and Dyer. *Tnoclemella Foerste.
* Hridotrypa Ulrich. **Orbipora Kichwald.
*Tnoclema Ulrich. ** Hsthomopora, hew genus.

Division INTEGRATA Ulrich and Bassler.

Trepostomata in which the boundaries of adjoining zocecia are
sharply defined by a black divisional line:

Family AMPLEXOPORID Ulrich and Bassler.

Amplexopora Ulrich. Rhombotrypa Ulrich and Bassler.
Monotrypella Ulrich. _ *Petalotrypa Ulrich.

Family HALLOPORIDA, new name.

* Hallopora, new name. Calloporella Ulrich.
Calloporina Ulrich and Bassler.

Family TREMATOPORIDA Ulrich.

* Trematopora Hall. * Hemiphragma Ulrich.
*Batostoma Ulrich. ** Dittopora Dybowski.
Stromatotrypa Ulrich. *Diplotrypa Nicholson.

*Anaphragma Ulrich and Bassler. * Monotrypa Nicholson.
Division AMALGAMATA Ulrich and Bassler.

Family MONTICULIPORID Nicholson (emended Ulrich).

The most important characteristic of this family, as emended by.
Ulrich, is the occurrence of the convex plates known as the cysti-
phragm. These curved structures are limited to the zoccial tubes,
where they form continuous series lining the walls. In most of the
genera the curve is complete, but in Orbignyella and Mesotrypa the
cystiphragms are often so slightly curved that they have the appear-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 179

ance of being merely oblique diaphragms. The use of the cysti-
phragms is not known, but it is possible that they represent modified
ovicells.

The method of zoarial growth in the family varies from incrusting
through lamellate, massive, and ramose, to bifoliate, intertwining
fronds. It is noteworthy that the massive, free forms of Prasopora,
the bifoliate forms of Peronopora, and the delicate incrusting zoaria
of Atactoporella, ali of which are very abundant in certain faunas of
the North American Ordovician, should be entirely absent in the
Russian deposits.

Genus MONTICULIPORA D’Oprbigny.

Monticulipora D’OrBteny, Prodr. de Pal., vol. 1, 1850, p. 25.—M1tnE-Epwarps,
Hist. Nat. des Corall., vol. 3, 1860, p. 272.NicHotson, Paleozoic Tabulate
Corals, 1879, p. 269; The Genus Monticulipora, 1881, p. 99.—Utricu, Journ.
Cincinnati Soc. Nat. Hist., vol. 5, 1882, pp. 153, 232.—Foorp, Contr. Micro-
Pal. Cambro-Sil., 1883, p. 7—Uxricu, Geol. Surv. Illinois, vol. 8, 1890, pp.
370, 407; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 217;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 272.—Simpson, Four-
teenth Ann. Rep. State Geologist New York for the year 1894, 1897, p. 577.—
Nicks and Basster, Bull. 173, U. 8. Geol. Surv., 1900, p. 28.—Uzricu and
Basser, Smiths. Mise. Coll., vol. 47, 1904, p. 15.

Peronopora (part) NicHotson, The Genus Monticulipora, 1881, p. 215.

Originally this genus was the resting place for a most heterogeneous
lot of species, but to-day, through the work of Ulrich, its definite
characters, so clearly shown in thin sections, have been so well
indicated that there is no longer any excuse for erroneous generic
identification. The generic characters are, first, the occurrence of
cystiphragms in the zoccial tubes, both in the axial and peripheral
regions, and, second, the peculiarly granulose wall structure per-
taining to both zoccia and mesopores. This combination of char-
acters has been found in species ranging through all the various forms
of growth save the bifoliate. The mesopores also, when present,
are variable in number. The acanthopores are usually small and
numerous, but differ in their microscopic features from those of all
the other families of the Trepostomata. The structure of the acan-
thopores in Monticulipora is much like that of the granulose walls,
but the distinct central perforation and concentric rings of tissue
seen in so many forms are wanting entirely.

Genotype.— Monticulipora mammulata D’Orbigny. Upper Ordo-
vician (Maysville) of the Ohio Basin.

MONTICULIPORA ARBOREA BISPINULATA, new variety.
Text fig. 93.

Cir. Monticulipora arborea Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol.
3, pt. 1, 1893, p- 220, pl. 20, figs. 1-9, 13, 14.

Zoarium incrusting, both of the type-specimens forming thin
expansions less than 20 mm. in diameter upon brachiopods. Surface

180 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

smooth; macule of slightly larger zocecia at regular intervals but
indistinctly visible; zocecial aperture small, polygonal, nine to ten
in 2 mm., with rather thick, minutely granular walls bearing acan-
thopores of some size, one or two to a zocecium; mesopores wanting.

The internal characters agree in all respects with. typical species
of the genus. The minutely granulose walls and distinctly granulose
acanthopores, and the absence of mesopores, are well brought out
in tangential sections, while vertical sections show the usual cysti-
phragms forming either a single or double row in each zoecial tube.

Tt is possible that more material may show the incrusting expan-
sions upon which the variety is founded to be nothing but the base
of ramose zoaria. In this event the varietal name is almost useless,

Fig. 93.—MONTICULIPORA ARBOREA BISPINULATA. @, ONE OF THE TYPE-SPECIMENS, NATURAL SIZE,
INCRUSTING A BRACHIOPOD FRAGMENT; 6 AND c, TANGENTIAL SECTION, X20, AND A PORTION, X30, SHOW-
ING THE TWO SETS OF GRANULOSE ACANTHOPORES AND THE WALL STRUCTURE; d AND €, A VERTICAL
SECTION, X20 AND X30, WITH THE CYSTIPHRAGMS LINING BOTH SIDES OF THE TUBES. WASSALEM BEDS
(D3), UXNORM AND GUT SACK, ESTHONIA.

since in practically every other feature the structure is precisely as
in If. arborea Ulrich. It is true that the granules of the walls in the
variety are so large that they have the appearance of acanthopores,
thus with the real acanthopores giving the idea of two sets of these
structures. Upon this character and the incrusting growth I have
distinguished the Russian specimens as a variety.

Occurrence.— Monticulipora arborea is a ramose form described by
Ulrich from the Clitambonites beds of the Lower Trenton in Min-
nesota and Iowa. The species reappears in higher beds of the
Trenton formation in Kentucky. Variety bispinulata is represented
by two incomplete specimens from the Wassalem beds (D3) at
Uxnorm, near Reval, and at Gut Sack, Esthonia.

Cotypes.—Cat. Nos. 57268, 57269, U.S.N.M.

British Museum, thin section of a type-specimen.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 181

MONTICULIPORA DAGOENSIS, new species.
Text fig. 94.

Zoarium a small, incrusting mass with a smooth, celluliferous
surface bearing inconspicuous macule. The type-specimen is about
a centimeter in diameter and a millimeter thick, and is growing upon
a species of Heliolites. The surface presents no unusual features
unless it is slightly etched with acid and then examined, when moist-
ened, with a hand lens, when distinct acanthopores may be seen at
many of the junction angles of the zoccia. Such a view also shows
large and somewhat numerous mesopores as well as the cut edges of
the ecystiphragms which appear in the zoccial tubes as circular or
semicircular les. The apertures are small, polygonal, thin-walled,
with six in 2 mm., and, on the average, 0.23 mm. in diameter. The

"ABS
Fic. 94.—MONTICULIPORA DAGOENSIS. @, TANGENTIAL SECTION, X20, ILLUSTRATING THE DISTINCT ACAN-
THOPORES AND OTHER FEATURES OF THE SPECIES; 0, PORTION OF SAME, X35, SHOWING IN ADDITION THE
GRANULOSE WALL STRUCTURE}; C, VERTICAL SECTION, X20, THROUGH THE MATURE REGION OF THE ZOA-
RIUM, EXHIBITING CLOSELY TABULATED MESOPORES AND ZOG@CIA WITH A DOUBLE ROW OF CYSTIPHRAGMS.
LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND OF DAGO.

mesopores are unusually large, sometimes almost equaling the
zocecia from which they can always be distinguished by their lack of
cystiphragms. In addition to the structure described, a tangential
section brings out the peculiar granulose wall structure characteristic
of the genus.

The incrusting growth, small, angular, thin-walled zoccia, large,
numerous mesopores and well marked acanthopores, are characters
of the present species which will separate it from all described forms
of the genus.

Occurrence.—Rare in the Lyckholm limestone (F1) at Kertel,
island of Dago, Baltic Sea.

Holotype.—Cat. No. 57270, U.S.N.M.

British Museum, thin section of the type-specimen.

Genus ORBIGNYELLA Ulrich and Bassler.

Orbignyella Utricw and BassteR, Smiths. Misc. Coll., vol. 47, 1904, p. 18.—
Basser, Bull. 292, U. 8. Geol. Surv., 1906, p. 26.

This genus was proposed for Monticuliporide which differ from
Monticulipora in wanting its irregularly granulose wall structure,

182 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

and in having cystiphragms so poorly defined that they appear more
like merely curved diaphragms. A third difference noted was in the
acanthopores, which, in Monticulipora, are imperfectly defined,
eranulose spots, while in Orbignyella they are sharply defined, well-
developed structures, as in the Heterotrypide.

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Fic. 95.—ORBIGNYELLA GERMANA. @, THE TYPE-SPECIMEN, NATURAL SIZE; 6, VIEW OF THE USUAL CHARAC-
TERS SEEN IN TANGENTIAL SECTION, X20; c, TANGENTIAL SECTION, X20, SHOWING DEVELOPMENT OF ACAN-
THOPORES IN DIFFERENT STAGES OF THE ZOARIUM. THE STRUCTURE OF THE MOST MATURE ZONE IS SHOWN
IN THE LOWER HALF OF THE FIGURE; d, PORTION OF THE SAME, X35, SHOWING MINUTE STRUCTURE IN
MORE DETAIL; €, VERTICAL SECTION, X20, WITH ACANTHOPORES LITTLE DEVELOPED; {, ANOTHER VERTICAL
SECTION, X20, SHOWING THE NUMEROUS DIAPHRAGMS AND STRONG ACANTHOPORES OF THE MATURE
REGION (@) WITH A SHORT IMMATURE ZONE (6). WASSALEM BEDS (D3), UXNORM, ESTHONIA.

Genotype-—Orbignyella sublamellosa Ulrich and Bassler. Middle
Ordovician (Stones River) of Tennessee.
ORBIGNYELLA GERMANA, new species.
Text fig. 95.

Cir. Monticulipora lamellosa Uxricu, Geol. Surv. Illinois, vol. 8, 1890, p. 408,

pl. 32, figs. 44D.
Zoarium a globular mass about 10 mm. in diameter and 15 mm.
in height; surface smooth, macule inconspicuous and distinguishable
only by the presence of zocecia slightly larger than the ordinary.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 183

Zocecial apertures polygonal, with thin walls, often bearing large
acanthopores; six and one-half to seven zoccia in 2 mm. ‘True
mesopores practically absent, the mesopore-like spaces seen in
tangential sections probably representing young zocecia.

The most striking feature of thin sections is the presence of large
acanthopores, numbering about one to a zowcium. ‘These are best
shown in tangential sections where they appear as well defined,
centrally perforated, circular spots of darker tissue made up of
concentric rings. The acanthopores are likewise conspicuous in
both vertical and tangential fractures, so that thin sections are not
necessary in identifying the species. Vertical sections show rather
numerous straight or slightly curved diaphragms, four or five occur-
ring in a tube diameter in the more crowded portions, but two to
three being the more usual number.

Apparently the closest ally of the species is the American form
Orbignyella lamellosa (Ulrich), from the Richmond (Fernvale) shales
of Ilmois. The latter grows into lamellate expansions with thin-
walled zoccia (eight in 2 mm.), moderately large acanthopores, and
straight or curved diaphragms averaging half a tube diameter apart.
The different methods of growth, slightly larger zocecia (six and one-
half to seven in 2 mm.), larger acanthopores and more numerous
diaphragms of the Russian form are relied upon in founding this new
species, although its intimate relationship to O. lamellosa is recognized.

Occurrence.—Apparently rare in the Wassalem beds (D3) at
Uxnorm, near Reval, Esthonia.

Holotype.—Cat. No. 57271, U.S.N.M.

British Museum, thin section of the type-specimen.

ORBIGNYELLA EXPANSA BALTICA, new variety.
Text fig. 96.
Cir. Orbignyeila expansa BassutER, Bull. 292, U. 8. Geol. Surv., 1906, p. 26,
pl. 10, figs. 5-8.

_ The specimen upon which this new variety is founded occurs as an
incrustation 3 mm. in thickness, upon a Heliolites. Its diameter is
about 20 mm., so that it is believed with further growth the zoarium
might have become a free, lamellate, epithecated expansion. All of
the zocecial characters save one are as in Orbignyella expansa from the
Niagaran (Rochester) shale of North America. The one exception
is the small number of cystiphragms in the specimen under discus-
sion and their comparative abundance in the typical form of the
species. The intimate relationship of the species and variety is thus
apparent, and the latter represents undoubtedly only an earlier
appearance of the species. Making allowance for the possible differ-
ence in growth and the variation in development of cystiphragms, the
following description of O. expansa will serve equally well for the
recognition of the variety baltica.

184 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Zoarium of lamellate, epithecated expansions composed of one
or more layers, each of which is usually several millimeters in thick-
ness. Surface smooth, but exhibiting conspicuous clusters composed
of zocecia attaining a diameter one and one-half times as great as
that of the intermacular zoccia. Zoccia polygonal, thin walled,
four in 2 mm., counting from the center of a macula, or six of the
ordinary ones in the same space; when well preserved, showing minute
granulations along the walls and small acanthopores usually at the
angles. Mesopores wanting. Zocecial tubes thin walled in the short
axial region, slightly thickened in the peripheral, where they con-
tain a rather crowded series of curved diaphragms, three usually
occurring in the distance of a tube diameter.

Occurrence.—Rare in the Lyckholm limestone (F1), at Kertel,

Fic. 96.—ORBIGNYELLA EXPANSA BALTICA. @, TANGENTIAL SECTION, X20, PASSING THROUGH A ZONE OF CURVED
DIAPHRAGMS; 0, SEVERAL ZOG@CIA OF THE SAME, X35; ¢€, VERTICAL SECTION, X10, THROUGH AN ENTIRE
ZOARIAL LAYER; d, PORTION OF THE SAME SECTION, X20. LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND OF
DAGo.

island of Dago. The species is not uncommon in the Niagaran
(Rochester) shale of New York and Canada.

Holotype.—Cat. No. 57272, U.S.N.M.

British Museum, thin section of the type-specimen.

Genus HOMOTRYPA Ulrich.

Homotrypa Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 240.—
Foorp, Contr. Micro-Pal. Cambro-Sil., 1883, p. 9.—Mituer, North Amer.
Geol. and Pal., 1889, p. 309.—Utricu, Geol. Surv. Illinois, vol. 8, 1890,
pp. 370, 409; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 235;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 273.—Simpson,
Fourteenth Ann. Rep. State Geologist New York for the year 1894, 1897, p.
575.—NiIcKLES and BassueR, Bull. 173, U. 8. Geol. Surv., 1900, p. 29.—
BasstER, Proc. U. 8. Nat. Mus., vol. 26, 1903, p. 565.—Cumines, Thirty-
second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 748.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 185

Numerous typical species of this interesting genus occur in the
faunas of late Trenton and of Cincinnatian ages, believed to have been
derived from the south Atlantic. The northern Atlantic or Arctic
types occur chiefly in the Black River and earliest Trenton forma-
tions, and in America are known mainly from deposits in Minnesota
and the neighboring States. Of these latter species, Homotrypa sub-
ramosa@ Ulrich and H. similis Foord are the most abundant and wide-
spread species in America, and their geographic range has now been
extended to the Baltic region by the discovery of specimens in several
of the Russian formations. Each of these two species is quite unlike
the Cincinnatian type of the genus and may be taken as typical of a
subgeneric division. Thus, Homotrypa sumilis shows a tendency to
variation toward Hridotrypa, while the acanthopores and the cysti-
phragms of H. subramosa recall Monticulipora.

The zoarium in Homotrypa is of ramose or frondescent, smooth or
monticulated branches made up of polygonal zocecia with thin,
finely crenulated walls and few diaphragms in the axial region, and
thicker walls lined by cystiphragms in the peripheral zone. _ Meso-
pores are either absent or are restricted to the macule, but acantho-
pores are generally present. The ramose forms of Monticulipora
have great similarity to Homotrypa externally, but a thin section of
the former shows a granulose wall structure very different from the
clearer, more distinct walls of Homotrypa.

Genotype.—Homotrypa curvata Ulrich. Upper Ordovician (Mays-
ville), Ohio Valley.

HOMOTRYPA SIMILIS Foord.
Text figs. 97, 98.

Homotrypa similis Foorp, Contr. Micro-Pal. Cambro-Sil., 1883, p. 10, pl. 2,
figs. 2-2d—U.ricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 242, pl. 20, figs. 28-33.

This characteristic American Lower Trenton bryozoan is repre-
sented in the Russian Ordovician by numerous specimens from the
Wassalem beds (D3) at Uxnorm. Careful comparison show these
examples to agree with the American types in all respects save that
as a rule the zoaria of the Russian specimens are better developed
and have less oblique zoecia. This latter fact is of slight importance,
since the study of the Paleozoic Bryozoa has shown that the greater
the development of the mature zone the more directly do the zoccia
open upon the surface. The essential characters of Homotrypa
similis are as follows:

Zoarium of subcylindrical or compressed branches 4 to 10 mm.
in diameter, dividing unequally and often so irregularly as to anasto-
mose. Surface smooth, with distinct, substellate maculz composed

186 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

of zocecia larger than usual surrounding a granulose central space
made up of mesopores. Zocecia oblique in youthful stages, direct
and angular in the more mature condition; about eight in 2 mm.

MY

Mag
ES

SU

Fic. 97.—HoMoOTRYPA SIMILIS. @, SURFACE OF A MINNESOTA SPECIMEN, X18, SHOWING A MACULA AND
NEIGHBORING ZOGCIA; 6, TWO PORTIONS OF A TANGENTIAL SECTION, X18, PREPARED FROM AN AUTHENTIC
CANADIAN EXAMPLE; C, VERTICAL SECTION, X18, OF THE SAME SPECIMEN, ILLUSTRATING THE CHARAC-
TERISTIC GRADUAL OUTWARD BEND OF THE TUBES AND THE TABULATION. LOWEST BEDS OF THE TRENTON
LIMESTONE, OTTAWA, CANADA, AND NEAR TRENTON FALLS, NEw YORK. (AFTER ULRICH.)

Acanthopores inconspicuous at the surface; mesopores absent save
in the macule.
The views presented in tangential sections of both American and

Fic. 98.—HOMOTRYPA SIMILIS. @, FRAGMENT OF A BRANCHED ZOARIUM, NATURAL SIZE; 6, TANGENTIAL
SECTION, X20, ILLUSTRATING THE STRUCTURE CORRESPONDING TO THE UPPER HALF OF FIGURE 97; 8, c,
VERTICAL SECTION OF SAME SPECIMEN, X20, SHOWING IDENTITY WITH THE INTERNAL STRUCTURE OF
AMERICAN EXAMPLES. WASSALEM BEDS (D3), UXNoRM, ESTHONIA.

Russian specimens are shown in the accompanying illustrations.
The marked peculiarities of the species are best seen in vertical sec-
tions where the tubes are noted to bend outward very gradually.
In the immature region the diaphragms are but slightly curved;

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 187

as the mature region is approached these bend more and more until
they pass into the usual combination of cystiphragms and diaphragms
characteristic of the genus. In the mature region as many as five
cystiphragms may occur in a tube diameter, and often a double row
of these structures may be noted. In sections of old examples the
cystiphragms are observed to be obscured near the surface by a solid
filing, which, with the gradually outward bend of the tubes and the
crowded cystiphragms and diaphragms, imparts a peculiar aspect
to the species and makes it easy of recognition.

Occurrence.—Not uncommon in the Wassalem beds (D3) at Ux-
._ norm, near Reval, Hsthonia. In America the species is known
from the Clitambonites and Nematopora beds of the Lower Trenton
in Minnesota, Iowa, and Wisconsin, and at Ottawa, Canada.

Plesiotype—Cat. No. 57273, U.S.N.M.

British Museum, specimens and one thin section of the Russian
type.

HOMOTRYPA SUBRAMOSA Ulrich.

Text figs. 99, 100.

Homotrypa subramosa Uuricn, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 81; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt.
1, 1893, p. 239, pl. 19, figs. 21-28; Zittel’s Textbook of Paleontology (Eng.
ed.), 1896, p. 2738, fig. 451 A-C (not D=H. separata Ulrich).

Several irregularly dividing subramose young specimens of Homo-
trypa from the Kuckers shale show all the surface characters of H.
subramosa, even to the shallow, zoccial apertures exposing the
eystiphragms. ‘This similarity is porue out in the internal structure,
wuich, by comparison of the two sets of figures given here, Ipnbe
for Appt eae in the age of the specimens, may be seen to be esa
Ulrich’s description of the species is as follows:

Zoarium subramose, frequently though irregularly divided; branches compressed
or subcylindrical, their extremities often bulbous. Size of branches varying greatly,
the smallest 4 or 5 mm. in diameter, the largest 6 to 9 mm. thick, and as much as 25
mm. wide. Average specimens are about 6 mm. thick and between 8 and 12 mm.
wide, with the total height of zoarium rarely exceeding 60 mm. Surface without
monticules, nor are the clusters of large cells very conspicuous. Zocecia with rather
thin walls and polygonal, direct apertures; 12 to 14 in 3 mm. Zoccial apertures
shallow, exposing the cystiphragms when in a good state of preservation. These
structures leave but a small opening, and when the fossil has suffered a little from
attrition (a frequent occurrence in the beds holding the species most abundantly) in
which case the true walis are obscured or cut away, the appearance is very deceptive,
- the apertures seeming to be very small and oblique, and much the greater part of
the surface occupied by wall substance. Acanthopores varying in number and
size, sometimes as numerous as two to each zocecium. More commonly the number
is little more than half that extreme. In many cases they are large enough to con-
stitute a marked external feature. In others, however, apparently in an equally
good state of preservation, they are so small that it is difficult to detect them even
with the aid of a good lens.

92602°—Bull. 77—11——14

188 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The distribution of the diaphragms and cystiphragms is sufficiently
illustrated in the accompanying figures.

2 eS Es
eee

od ys

Fic. 99.—HoMoTRYPA SUBRAMOSA. 4G, FRAGMENT OF A ZOARIUM, NATURAL SIZE; 6, SURFACE OF AN ORDINARY
FRAGMENT, <9, SHOWING THE CYSTIPHRAGMS IN THE ZOG@CIAL APERTURES; c, A TANGENTIAL SECTION, X18,
WITH ACANTHOPORES WELL DEVELOPED; d, TANGENTIAL SECTION, X18, WITH ACANTHOPORES LESS CONSPICU-
OUS; ¢, VERTICAL SECTION OF A TYPICAL EXAMPLE, X18. PHYLLOPORINA BED OF BLACK RiIvER (DECORAH)
SHALES, ST. PAUL, AND NEAR CANNON FALLS, MINNESOTA. (AFTER ULRICH.)

The Kuckers examples differ from the typical H. subramosa in
that the zoarium is somewhat smaller, the walls are thinner, the

Fic. 100.—HoMOTRYPA SUBRAMOSA. @, TANGENTIAL SECTION OF A RUSSIAN SPECIMEN, X20; 6, SEVERAL
ZOG@CIA OF THE SAME, X60; c, TWO PORTIONS OF A VERTICAL SECTION, PREPARED FROM A YOUNG EXAMPLE,
SHOWING THE IMMATURE AND MATURE REGIONS, X20. KUCKERS SHALE (C2), REVAL, ESTHONIA.

acanthopores less numerous and smaller, and lastly the clusters
of larger cells.are more conspicuous. All of these same differences
pertain to the early Trenton form which Ulrich named HZ. insigms,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 189

but later reduced to synonymy. The characters of H. insignis are
undoubtedly those of young examples of H. subramosa.

Occurrence.—The American occurrences are in the Black River
and earliest Trenton formations of Minnesota and lowa. In Russia,
the species is not uncommon in the Kuckers shale (C2) at Reval,
Esthonia.

Plesiotype.—Cat. No. 57274, U.S.N.M.

A specimen and thin sections from the Kuckers shale, Reval,
are in the collections of the British Museum.

Genus HOMOTRYPELLA Ulrich.:

Homotrypella Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minnesota,
1886, p. 83.—MitteR, North Amer. Geol. and Pal., 1889, p. 310.—ULricn,
Geol. Surv. Illinois, vol. 8, 1890, pp. 370, 412; Geol. and Nat. Hist. Surv.
Minnesota, vol. 3, pt. 1, 1893, p. 228—Simpson, Fourteenth Ann. Rep.
State Geologist for the year 1894, 1897, p. 586.—NicxLEes and BassiER,
Bull. 173, U. S. Geol. Surv., 1900, p. 29.

Three separate sections of this genus are represented in the Black
River and earliest Trenton rocks of North America. The first
comprises the typical species and consists of stout, ramose branches
with direct zocecia, numerous acanthopores and mesopores, and
long mature regions. The second section has short mature regions
and oblique apertures, while the third consists of species with a mass-
ive zoarium and strong acanthopores, hitherto referred to Prasopora.
All three sections are represented in the Russian Ordovician by
typical American species.

In growth and several other characters Homotrypella is quite similar
to Homotrypa, but it differs conspicuously in the presence of numerous
tabulated mesopores.

Genotype.—Homotrypella instabilis Ulrich. Middle Ordovician
(Black River) of the Mississippi Valley.

HOMOTRYPELLA INSTABILIS Ulrich.
Text figs. 101, 102.

Homoirypella instabilis Untricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 83; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, 1893,
p- 229, pl. 18, figs. 9-20.—Simpson, Fourteenth Ann. Rep. State Geologist of
New York for the year 1894, 1897, p. 586, figs. 168, 169.

Specimens which fall within the range of characters presented by
this very abundant Black River fossil are frequent in the Kuckers
shale. As indicated by the specific name, the species is somewhat
variable, yet almost every phase noted in the American specimens
has been duplicated in the Russian examples. In figure 101 I have
introduced a few of Ulrich’s excellent illustrations of the species, but
as these show the mature characters more clearly, another set of
drawings (fig. 102) to illustrate the young stages, is added. Ulrich

190 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

has given a good description of the American types which applies
equally well to the Russian specimens. His description, slightly
changed to agree with the present illustrations, follows:

Zoarium ramose, growth rather irregular; branches rounded, sometimes nodular
or lobate, and varying in diameter from 8 to 8 mm.; surface generally without monti-
cules, and when these are present they are low and broad; small maculze or clusters
of mesopores are not infrequently present. Superficial characters of zocecia and
mesopores variable. In some, and these are in most cases well-preserved examples,
the zocecial apertures are irregular both in form and arrangement, with thin walls,
partly separated by mesopores numbering one or two to each zocecium. In these

a

Fic. 101.—HOMOTRYPELLAINSTABILIS. @ AND 6, TWO FRAGMENTS, NATURAL SIZE; C, SURFACE OF A WELL-
PRESERVED EXAMPLE, X18; d, TANGENTIAL SECTION, X18, PREPARED FROM THE ORIGINAL OF a;
€, ANOTHER TANGENTIAL SECTION, X18, SHOWING PORTION OF A MACULA AND ZO@CIA WITH MORE
NUMEROUS ACANTHOPORES; f, SMALL PORTION OF A TANGENTIAL SECTION, X50, ILLUSTRATING THE
MINUTE STRUCTURE MORE CLEARLY; g, VERTICAL SECTION, X18, WITH THE USUAL DISTRIBUTION OF
CYSTIPHRAGMS AND DIAPHRAGMS, RHINIDICTYA BED OF THE BLACK RIVER (DECORAH) SHALES, ST.
PAUL AND MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

specimens the acanthopores are small yet prominent and sharp, and number from one
to three to each zocecium. The mesopores are always smaller than the zoccia,
but vary occasionally in shape, size, and arrangement. In many other examples
both the zocecia and mesopores are smaller and their walls correspondingly thick,
while the acanthopores are blunt and thicker. In most cases a little wearing suffices
to obscure the mouths of the mesopores, so that they are readily overlooked. Twelve
or thirteen of the zocecia occur in 3 mm.

Internal characters —Tangential sections of this species present an unusual variety
ofappearances. In the majority of sections, providing they are not too deep, the walls
of the cells are very thick, with not a sign of cystiphragms in the zoccial cavities.
When a second or peripheral series of cystiphragms has been developed a very different
appearance is obtained. Now the walls are thinner, and a cystiphragm, leaving from
one-third to one-half of the zocecial cavity open, is to be seen in each of the zocecia.
Tn all cases the polygonal lines of contact between the two sets of cells is sharply de-
fined, and the walls of both approximately of equal thickness. The acanthopores

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 191

are conspicuous features of these sections, but their relative abundance varies some-
what in different examples. In the axial region of vertical sections the walls of the
tubes are very thin and finely wavy, and the diaphragms straight and remote, or
wanting entirely. As the tubes enter the peripheral region the number of diaphragms
is greatly increased, the walls thickened, and cystiphragms, mesopores, and acan-
thopores developed. The mesopores are distinguished from the zocecia by their
shortness and in having no cystiphragms. The latter structures number from three
or four to fifteen in a direct series in each zocecial tube. In most cases they occur
only in the region intervening between the fully matured peripheral and the imma-
ture axial region. Beyond them the diaphragms are crowded and essentially hori-
zontal. In the mesopores the diaphragms are often thick and situated about the same
distances apart as in the zocecial tubes, with from fourteen to seventeen inl mm, In
the axial region of transverse sections the zocecial tubes are of unequal sizes and of
peculiarly irregular shapes.

Fic. 102.—HOMOTRYPELLA INSTABILIS. @,6, AND C, VERTICAL SECTIONS, X20, SHOWING DIFFERENT STAGES
IN THE DEVELOPMENT OF THE MATURE ZONE; d, TANGENTIAL SECTION, X20. KUCKERS SHALE (C2),
BARON TOLL’S ESTATE, HSTHONIA.

Many of the Russian examples agree with the above description,
but a few of them are young examples which have furnished the thin
sections illustrated in figure 102. In figure 102 a, the vertical sec-
tion of a stage so youthful that the mature region is scarcely devel-
oped, is shown. Distinct eystiphragms are noted in the bend to the
mature zone but they are incomplete at their lower end. In figure
102 6, a slight advance in the development of cystiphragms may be
seen, and a further advanced stage, with the introduction of tabu-
lated mesopores, is illustrated in figure 102 c. In all of these vertical
sections it is evident that only the earliest cystiphragms are incom-
plete. Possibly their lower portion consisted of tissue too delicate
to show in thin sections. In older zowcia most of the early cysti-

192 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

phragms have enough tissue added to them to complete the structure.
A tangential section of a young example is shown in figure 102 d.

The ramose form of growth, numerous tabulated mesopores, and
zocecia lined with cystiphragms, are characters different from all
other Russian forms save Homotrypella cribrosa. The latter has a
more regularly inosculating form of growth, smaller branches, a short
mature region, and oblique aperture.

Occurrence.—Abundant in the Rhinidictya bed of the Black River
(Decorah) shales at St. Paul, Minneapolis, and other localities in
Minnesota. Common in the Kuckers shale (C2), Baron Toll’s estate,
and at Reval, and in the Echinospherites limestone (C1), 4 miles
east of Reval, Esthonia.

Plesiotype-—Cat. No. 57275, U.S.N.M.

British Museum, specimens and thin sections from the Kuckers,
Baron Toll’s estate.

st :
H@MOTRYPELLA CRIBROSA, new species.
Plate 13, text fig. 103.

Zoarium growing from a thick, small basal expansion into narrow,
compressed, rounded branches that inosculate at intervals of 10 mm.
or less until there results a broad expansion usually spread in a plane.
Branches 2 to 4 mm. in diameter, surface smooth but marked at
regular intervals by distinct solid clusters of mesopores. Zocecial
apertures oblique and long drawn out in young stages, direct,
polygonal, and thick-walled in old portions of the zoarium; seven
to eight zocecia in 2mm. Mesopores most abundant in the maculee
but comparatively few elsewhere and usually closed at the surface.
Well-defined acanthopores are also few but numerous granules sim-
ulating these structures are present in the most mature regions.

Vertical sections of this species are especially interesting. In the
immature zone the zoccial tubes are noticeably constricted where-
ever a diaphragm is inserted. In the outer portion of this zone large
cystiphragms occur and continue until the mature region is reached,
where the zocecial walls thicken, mesopores are introduced, and the
cystiphragms decrease in size but are in a crowded series. The dia-
phragms and cystiphragms of the immature zone average the distance
of a tube diameter from each other. Diaphragms are sparsely devel-
oped in the mature zone but here three to four eystiphragms occur
in the width of a zoccium. Other features of vertical sections are
the gradual bend from the immature to the mature zone, the narrow-
ness of the latter, and the thickening of the walls and closing of the
mesopores by layers of tissue as the surface is approached.

Tangential sections taken close to the surface of mature specimens
show polygonal thick-walled zocecia with an occasional closed inter-
space. True acanthopores are occasionally noted, but smaller gran-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 193

ules, as shown in figure 103 c,are more common. In this figure about
half of the zocecia show cystiphragms cut by the section.

The smooth branches inosculating so as to form a cribrose zoarium,
and the internal features shown in the figure, are sufficient to separate
this from similar small-stemmed species. The same species, differ-
ing only in having less numerous diaphragms in the immature zone,
occurs in the Black River shales of Minnesota.

Occurrence—Common in the Wassalem beds (D3) at Uxnorm,
Esthonia; the same species, or at least a variety, is equally abundant

Fig. 103.—HOMOTRYPELLA CRIBROSA. @, VERTICAL SECTION, X20, ILLUSTRATING THE SHORT MATURE ZONE
AND TABULATION; 0, TANGENTIAL SECTION, X20, SHOWING CHARACTERS OF THE EARLY PART OF THE
MATURE ZONE IN THE UPPER HALF AND THE LATER PART IN THE LOWER HALF; c, SEVERAL ZOGCIA OF
THE SAME SECTION, X35. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

in the Black River (Decorah) shales at Fountain and other localities
in Minnesota. ;

Holotype.—Cat. No. 57278, U.S.N.M.

Specimens and thin sections from the Wassalem beds, Uxnorm,
are in the collections of the British Museum.

HOMOTRYPELLA HOSPITALIS CRASSA (Ulrich).
Text figs. 104, 105.

Atactoporella crassa Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 225, pl. 15, figs. 18-21.

Cir. Monticulipora (Prasopora) selwynit var. hospitalis Nicnhouson, Genus Monti-
culipora, 1881, p. 209, fig. 45.

One of the most abundant and characteristic fossils of the Rich-
mond formation in North America is the bryozoan described by
Nicholson as Monticulipora (Prasopora) selwynw var. hospitalis,
later referred by Ulrich as a valid species of Prasopora. The small,
more or less rounded zoarium, with zocecia having numerous acan-
thopores, lined with cystiphragms and separated by closely tabu-
lated mesopores, make this form especially easy of recognition.
Detailed collecting in the American Black River and Trenton hori-
zons resulted in the discovery of a species or variety closely related
to the Richmond form, and now the study of the Russian Ordovician

194 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Bryozoa has greatly extended the geographical range of this lower
form. The occurrence in the Black River-Trenton and in the Rich-
mond strata of a species or variety closely related to a Richmond
form, and with apparently no connecting links in the intervening
strata, is in line with other faunal similarities of these formations.
As shown by further study, this early occurrence of the common
Richmond species was described by Ulrich as Atactoporella crassa,
but it is believed to be more in keeping with the facts to regard it as

N

.

Te
Sema
EU)

KS

Fic. 104.—HoOMOTRYPELLA HOSPITALIS CRASSA. ULRICH’S VIEWS OF ATACTOPORELLA CRASSA. @, TAN-
GENTIAL SECTION, X18, OF THE MINNESOTA TYPE; 6, VERTICAL SECTION OF THE SAME, X18, WITH THE
CHARACTERISTIC TABULATION OF ZOGCIA AND MESOPORES; C, SEVERAL ZOG@CIA IN TANGENTIAL SECTION,
50, SHOWING THE STRUCTURE OF THE MOST MATURE ZONE. CLITAMBONITES BED OF THE LOWER
TRENTON, NEAR CANNON FALLS, MINNESOTA.

a variety of Prasopora, now Homotrypella, hospitalis. The reference
of Prasopora hospitalis to Homotrypella is also believed to be nearer
the truth, because this species differs from typical Homotrypella only
in its massive form of growth. The following description is based
upon the Russian specimens.

Zoarium massive, growth beginning upon some foreign object and
continuing until a more or less regular, rounded colony results. In
the Russian specimen figured, growth has been about a fragment of
a brachiopod, almost completely enveloping the shell. Surface
marked by moderately elevated, rounded monticules, 3 mm. apart.
Under a hand lens the surface is seen to be finely spinulose because
of numerous acanthopores. The characteristic features distin-
guishing this from most associated bryozoans are seen either in thin
sections or in fractures moistened and examined under a strong
hand lens. In either case the numerous cystiphragms lining the
zocecial walls and the closely tabulated mesopores are evident, while
the abundant acanthopores are seen to best advantage in tangential
sections. Cystiphragms are found most often lining one side of the
zocecia, but sometimes, as in figure 105 e, both sides show them.
Ordinarily 30 cystiphragms may be counted in 2 mm., while the

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 195

mesopores hold approximately the same number of straight dia-
phragms. In deep tangential sections both the zocecia and meso-
pores are thin walled and polygonal, but as the surface is approached,
the zoccial walls thicken at the expense of the mesopores. In the
outermost parts of the mature region, calcareous tissue is often devel-
oped in the mesopores to such an extent that the latter are obliterated.
Hight zocecia in 2 mm.

Closely compared with typical Homotrypella hospitalis, variety
crassa differs but slightly and apparently only in having more
crowded diaphragms and cystiphragms and less developed acantho-

Fig. 105.—HOMOTRYPELLA HOSPITALIS CRASSA. @, A RUSSIAN EXAMPLE, NATURAL SIZE; 0, TANGENTIAL
SECTION, 40, THROUGH THE LESS MATURE PORTION OF A ZOC@CIAL LAYER; C, TANGENTIAL SECTION, X40,
THROUGH THE MOST MATURE REGION OF THIS SPECIMEN, WHERE THE MESOPORES ARE OBSCURED BY A
DENSE TISSUE; d, €, AND f, THREE VERTICAL SECTIONS, X20, ILLUSTRATING THE CHARACTERS IN VARIOUS
PARTS OF THE ZOARIUM. IN d THE YOUNGEST STAGE IS FIGURED WITH THE IMMATURE ZONE, AND THE
EARLIEST PART OF THE MATURE REGION DISPLAYED. WASSALEM BEDS (D3), UXNORM, ESTHONTIA.

pores. Although even these differences are subject to slight varia-
tion, it is believed that a varietal name for the older form is justified.

Occurrence.—The typical form is abundant and characteristic in
the Richmond formation at many American localities; the variety
crassa is known from the Black River shales of Minnesota, Iowa, and
elsewhere, and from the lower Trenton rocks, particularly at West
Covington, Kentucky. The Russian specimen was found in the
Wassalem beds (D3) at Uxnorm, near Reval, Esthonia.

Plestotype-—Cat. No. 57279, U.S.N.M.

Thin sections of the Russian type are in the collections of the
British Museum.

196 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Genus MESOTRYPA Ulrich.

Mesotrypa Uuricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
257.—NicKLEs and BassterR, Bull. 173, U. 8. Geol. Surv., 1900, p. 30.—
Basser, Bull 292, U. S. Geol. Surv., 1906, p. 27.—Hznnie, Archiv. fur
Zool., vol. 4, No. 21, 1908, p. 29.

Diplotrypa (part) of authors.

Zoarium hemispheric, conical, or discoidal, generally free, with an
epitheca on the under surface; zocecia prismatic or cylindrical, with
oblique and sometimes funnel-shaped diaphragms, which are prob-
ably modified cystiphragms; zocecia more or less separated by angu-
lar mesopores, which become smaller with age, and are intersected
by numerous diaphragms; acanthopores generally present, some-
times of large size.

Genotype.—Diplotrypa infida Ulrich. Middle Ordovician (Black
River) of Minnesota.

This genus includes several groups of species, all of which agree in
having a massive zoarium of zocecial tubes crossed by curved dia-
phragms, and of closely tabulated mesopores with rather straight
walls. The typical group of the genus includes species with numer-
ous curved diaphragms and strong acanthopores, a combination of
characters which has not been found well developed in any of the
Russian forms, although two new species are referred to this division.
A second generic group, of which the American forms Mesotrypa
discoidea Ulrich and M.? rotunda Ulrich, from the Mohawkian rocks
of Minnesota, are typical, is represented by the very similar Russian
form I. discoidea variety orientalis. The latter group, with its few
curved diaphragms and absence of acanthopores, suggests alliance
with other genera, especially Diplotrypa. A third division of the
genus is known only from the specimens here described as M. mille-
poracea, new species, and the new variety parva, in which the absence
of acanthopores and the presence of very numerous and exceptionally
small mesopores are the main peculiarities.

MESOTRYPA DISCOIDEA ORIENTALIS, new variety.
Text fig. 106.

Cf. Mesotrypa discoidea Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 260, fig. 12.

Zoarium discoid with a flattened, concentrically wrinkled base and
a gently convex upper surface; an average example 6 mm. high and
20 mm. in diameter. Upper surface smooth, with macule of large
zocecia, inconspicuous, showing plainly only in thin sections. Zoce-
cial apertures polygonal, usually hexagonal in outline, with meso-
pores occupying the interspaces left between adjoining zocecial walls.
Acanthopores apparently absent. Walls of both zocecia and meso-

pores thin. Seven to eight zocecia in a distance of 2 mm.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 197

Although in surface characters this form is quite similar to several
associated forms, its internal features are striking enough to make
its recognition easy. The chief peculiarity seen in vertical fractures
or sections is the presence of exceedingly numerous diaphragms in
the mesopores and comparatively few of these structures in the
zocecia proper. In the mesopores 20 to 25 diaphragms occur in the
space of 1 mm., while in the immature region of the zoccia only 1

2%,
ny
|
5
5
Fj
2

i

mas Ba

Fic. 106.—MESOTRYPA DISCOIDEA ORIENTALIS. @, b, AND C, TOP, BASAL, AND SIDE VIEWS OF A ZOARIUM,
NATURAL SIZE; d, TANGENTIAL SECTION, 20, WITH THE MESOPORES SHADEL,, €, A PORTION OF THE SAME,
40, ILLUSTRATING THE SIMPLICITY OF STRUCTURE AND THE TENDENCY OF THE ZO@CIAL TUBES TO ASSUME
A HEXAGONAL OUTLINE; f, VERTICAL SECTION, X20, SHOWING PORTIONS OF TWO IMMATURE ZONES
BOUNDING A NARROW MATURE ZONE. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

may be found in the same distance. The mature region of the zocecia
occasionally have as many as 4 diaphragms, which in all cases are
straight or but slightly curved. These are placed on an average of
a tube diameter apart.

The Russian specimens are apparently closely related to Mesotrypa
discoudea Ulrich, from the Nematopora bed of the lower Trenton of
Minnesota, with which they agree closely in size of zocecia and num-
ber and tabulation of the mesopores. The two differ mainly in the

198 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

tabulation of the zocecia, which, in the Minnesota species, is closer and
often exhibits curved diaphragms. A second but minor difference
may be noted in the shape of the zowcia, which in MM. discoidea are
often rounded and in the variety orventalis are most often hexagonal.
The latter is apparently the European representative of the American
species, and the reference of both to Mesotrypa, in spite of their
numerous straight diaphragms, is believed to be in keeping with the
development of the genus. As remarked under the generic discus-
sion, these two forms and the following new species, in addition to
Mesotrypa rotunda Ulrich, form a small group differing from typical
forms of the genus in having straight diaphragms more often than
curved. In other respects, namely, the distinctly straight, well-
defined walls of both zocecia and mesopores and the close, compact
tabulation of the latter, the generic characters are those of Mesotrypa.
Of associated species, Orbipora distincta has a similar zoarium but
its zocecia are much larger, acanthopores are numerous, and meso-
pores are wanting. Dviplotrypa bicornis often has a similar external
aspect, but the difference in tabulation may be seen by comparison
of the text figures here given. This latter species likewise has the
moniliform mesopores and loose tabulation of Diplotrypa.
Occurrence-—Not uncommon in the Jewe limestone (Di), Baron
Toll’s estate, near Jewe, at St. Mathias, and Paeskill, Hsthonia.
Cotypes.—Cat. No. 57280, U.S.N.M.
Specimens and a thin section of the type-specimen are in the col-
lections of the British Museum.

MESOTRYPA EGENA, new species.

Text fig. 107.

The species for which the above new name is proposed is so much
like the preceding externally that an examination of its internal
structure is necessary for its identification. Both species agree in
having a discoid zoarium with a flat, concentrically wrinkled base
and a gently convex upper surface. Specimens of Mesotrypa dis-
coidea orientalis as a rule exhibit numerous mesopores at the surface,
while in M. egena mesopores are so few that the zoccia are polygonal
and in contact. The surest method of distinguishing the two, how-
ever, is by an examination of the tabulation, as shown in vertical
fracture or thin section. In the present species the zocecial dia-
phragms are from one to two times their own diameter apart in the
immature zone, but so crowded in the mature region that four dia-
phragms sometimes occur in a distance equal to their own diameter.
In these crowded zones the diaphragms are frequently so curved as
to resemble cystiphragms. In WV. discoidea orientalis the diaphragms

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 199

are a tube diameter distant in the most crowded part and three or
four times that distance from each other in the immature region.
Still another difference is the presence of small acanthopores in
M. egena, but these are so inconspicuous that they can be distin-
guished only in thin sections. The size of the zocecia and the tabu-
lation of the mesopores is practically the same in both species.

In spite of the great similarity to the preceding species, the present
form is believed to be more closely related to the type of the genus,
Mesotrypa infida (Ulrich), from the Black River shales of Minnesota,

Fic. 107._MESOTRYPA EGENA. @, SIDE VIEW OF TYPE-SPECIMEN, NATURAL SIZE; 6, TANGENTIAL SECTION
THROUGH THE MATURE ZONE, X20; c AND d, PORTIONS OF THE SAME, X35, SHOWING WALL STRUCTURE
AND VARIATIONS IN NUMBER OF ACANTHOPORES; 6 AND f, TWO PORTIONS OF A VERTICAL SECTION, X20.
KEGEL BEDS (D2), HABBINEM, ESTHONIA.

on account of the presence of small acanthopores and the numerous
curved diaphragms. ‘The acanthopores are much stronger and the
diaphragms more curved in M. infida, but certain portions of its
zoarium sometimes exhibit a structure resembling that in MM. egena.
Indeed, the latter may represent merely a poorly developed stage of
M. infida.

Occurrence.—Rare in the Kegel limestone (D2) at Habbinem,
Esthonia.

Holotype.—Cat. No. 57283, U.S.N.M.

Two thin sections of the type-specimen are in the British Museum
collections.

200 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.
MESOTRYPA EXPRESSA, new species

Text fig. 108.

This rather unusual form is particularly interesting in showing to
how great an extent mesopores which are abundant in the less mature
portions of a colony may be pinched out in the more mature zones.
This feature is best seen in vertical sections (fig. 108 e), although

SN)

Fic. 108.—MESOTRYPA EXPRESSA. d, SIDE VIEW OF THE TYPE-SPECIMEN, GROWING AROUND A HYOLITHES;
6, VIEW OF THE SAME EXAMPLE FRACTURED LENGTHWISE; C, TANGENTIAL SECTION, X20, THROUGH THE
MATURE REGION, ILLUSTRATING THE SCARCITY OF MESOPORES; d, A PORTION OF THE SAME, X35, WITH
THE WALL STRUCTURE MORE CLEARLY INDICATED; ¢€ AND f, TWO VERTICAL SECTIONS, X20, DIFFERING
ONLY IN THE DEVELOPMENT OF MESOPORES IN €, WHERE THEY DISAPPEAR BEFORE THE SURFACE IS
REACHED. KUCKERS SHALE (C2), REVAL, ESTHONIA.

tangential sections prepared from different parts of the zoarium will
exhibit the same variation in the number of mesopores. Such a
pinching out or disappearance of the mesopores as growth proceeds
is a characteristic of the genus as a whole, although it is seldom so
well shown as in the present instance.

The three zoaria studied form small, elongate masses incrusting a
species of Hyolithes. The fractured specimen from which the figured
thin sections were prepared is shown in figure 108 6, where the layers
of zocecia are seen proceeding from the clay filled body of the shell.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 201

The thin layer of cells is growing upon the flat side of the shell and
exhibits a structure that has been noted in all species growing upon
Hyolithes, namely that no true zoccia are found here. This portion
of the zoarium is made up exclusively of small cells differing from
mesopores only in having thicker walls. A discussion of this feature
is given on page 47, so that further remarks are unnecessary at this
point.

The zoarial surface in M. expressa is smooth and without distinct
macule, although groups of larger zocecia are present. The apertures
are quite regularly hexagonal in outline, with eight in 2mm. Meso-
pores practically absent at the surface, acanthopores apparently
wanting.

Tangential sections passing through the zoarium near the surface
show the great regularity in the shape of the aperture. The cut edges
of the curved diaphragms likewise frequently show in such sections
as curved lines crossing the apertures. Deeper tangential sections
exhibit mesopores and less regular zocecia.

The chief peculiarity of vertical sections has already been men-
tioned. The zoccial tubes are thin walled in the immature region,
where closely tabulated, narrow mesopores are developed in some
number. As the mature zone is approached, the mesopores become
smaller and finally disappear entirely. Here their place is taken by
a slight widening of the zocecia and an increase in the thickness of
their walls. Slightly curved diaphragms occur in the immature zone
at intervals averaging their own diameter. In the shorter mature
zone they are four or five times as numerous and are more curved,
in fact they are frequently arranged on top of each other in the
manner of true cystiphragms.

There is no described species near enough the present form to make
comparison necessary. Leptotrypa hexagonalis from the same forma-
tion has the same method of growth and similarly shaped apertures,
but its internal characters are quite different. A glance at the
fractured edge of a zoarium will suffice to distinguish the few hori-
zontal diaphragms of the Leptotrypa from the numerous curved
structure of the Mesotrypa.

Occurrence-—Rare in the Kuckers shale (C2) at Reval, Esthonia.

Holotype.—Cat. No. 57284, U.S.N.M.

British Museum, one specimen and thin sections.

MESOTRYPA MILLEPORACEA, new species.
Text fig. 109.

Zoarium at first incrusting and then becoming a free, lamellate
expansion several centimeters wide and averaging 5 mm. in thickness.
Celluliferous face smooth, with indistinct macule; noncelluliferous
side marked with a strongly wrinkled epitheca. Zocecial apertures

202 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

rather large, subpolygonal to rounded according to the number of
mesopores, thin-walled, fivein 2mm. Mesopores exceptionally small
and numerous, the interzoecial spaces sometimes being filled by
three distinct rows of them. Acanthopores wanting.

Vertical sections show erect tubes, in general perpendicular to the
basal epitheca, with a very short, inconspicuous immature region.
These zocecia are crossed by numerous, more or less curved dia-

Fic. 109.—MESOTRYPA MILLEPORACEA. @, THE EPITHECAL SIDE OF A FRAGMENTARY ZOARIUM, NATURAL
SIZE; 0 AND C, A TANGENTIAL SECTION, X20, AND SEVERAL ZOGCIA, X35, THROUGH THE REGION IN WHICH
THE MESOPORES ARE SMALLEST AND MOST NUMERCUS; d, TANGENTIAL SECTION OF THE SAME SPECIMEN,
X20, SHOWING LARGER, LESS NUMEROUS MESOPORES; €, VERTICAL SECTION, X20, PASSING THROUGH
PORTIONS OF TWO LAYERS OF ZOGCIA. CHASMOPS LIMESTONE, SOUTH OF BODAHAMN, ISLAND OF OELAND.

phragms with three to five in a tube diameter. A variety of appear-
ances is presented by these diaphragms in such thin sections. Some
are straight, others are slightly oblique, while still others are curved
as much as in the ordinary cystiphragm. The mesopores are always’
numerous, but vary in number and size at different stages of growth.
In the early portion of the mature region they are seen as single
tubes crossed by thin diaphragms at intervals varying from one to
two times their own diameter. Their appearance and number at
this stage, as shown in tangential sections, is indicated in figure 109 d.
In the later stages of the mature region their diameter decreases and

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 203

two or more exceedingly small tubed mesopores occupy the same
interzocecial space. This particular region affords a unique tan-
gential section showing quite large rounded zoccia and numerous
exceptionally small, angular mesopores. This condition is most
often presented at the surface of a zoarium and is a distinct aid in
the identification of the species. The tangential view, seen in figure
109 6, is the usual aspect of the species both at the surface and in
sections.

The large zocecia and the very numerous small mesopores are alone
quite striking, but in combination with the oblique diaphragms and
lamellate method of growth afford characters unlike any other

Fig. 110.—MESOTRYPA MILLEPORACEA PARVA. @, A ZOARIUM, X2, SHOWING THE USUAL FORM; 0 AND ¢,
A TANGENTIAL SECTION, X20, WITH SEVERAL ZOGCIA, X35; d, VERTICAL SECTION, X20, SHOWING ESSEN-
TALLY THE SAME STRUCTURE AS IN FIGURE 109 e. KUCKERS SHALE (C2), BARON TOLL’S ESTATE,
ESTHONIA.

bryozoan save the following variety parva, which, as the name indi-

cates, is a smaller form.

Occurrence.—The type-specimen was found by Dr. F. A. Bather
in the Chasmops limestone south of Bédahamn, island of Oeland.
An example incrusting the epithecated base of Dvplotrypa petro-
politana, from the Jewe limestone (D1), Baron Toll’s estate (Cat.
No. 57285, U.S.N.M.), differs only in having slightly smaller zoecia.
Other localities are Kuckers shale (C2), Baron Toll’s estate (Cat. No.
57286, U.S.N.M.), and Kegel limestone (D2), Kegel, Esthonia (Cat.
No. 57287, U.S.N.M.).

The type-specimen and figured thin sections are in the collections
of the British Museum.

MESOTRYPA MILLEPORACEA PARVA, new variety.
Text fig. 110.

The internal structure of the specimens distinguished as above is
exactly the same as in the typical form of the species, and the differ-
ences relied upon in founding the variety are the occurrence, first, of
a, distinct method of growth and, second, of much smaller zoecia.
Ordinarily such differences, particularly the latter, would be con-

92602°—Bull. 77—11——15

204 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

sidered of specific importance, but the practical identity of all the
other characters in each is believed to show close relationship.

The zoarium of the variety consists of small, globular or ovoid
bodies, less than 5 mm. in their greatest diameter, formed by the
layers of zocecia incrusting some foreign object. Eight specimens
with this form of growth have been seen. Comparing figures 109 b
and 1106, the distinctly smaller zoccia of the variety are plainly
evident, as is also the practical identity of the other characters.

Occurrence.—Apparently common in the Kuckers shale (C2),
Baron Toll’s estate, near Jewe, Esthonia.

Cotypes.—Cat. No. 57288, U.S.N.M.

Specimens and thin sections are in the collections of the British
Museum.

Family HETEROTRYPID Ulrich.

The meager development of this family in the Russian strata seems
upon first thought quite unusual, considering the abundant American
representation, but a study of the generic distribution offers an
explanation for this disparity. Species of Heterotrypa are quite
abundant in the various Trenton and Cincinnatian formations of
North America, but are absent entirely from strata holding the Black
River and other Atlantic faunas. They also have not been discov=
ered in European rocks. Dekayella, according to present knowledge;
has its origin in a Black River species, D. prenuntia, common to
both continents. In later times, representatives of the genus spread
to other faunas so that Dekayella lost its value as a strictly Atlantic
type. Thesame is true for Stigmatella and Leptotrypa, both of which
have identical Russian and American representatives in Black River
time. Cyphotrypa is represented in the Black River by a few species,
but its greatest specific development is in faunas of later age, restricted
so far as known, to the North American interior seas. Dekayia,
Petigopora, and Atactopora are known only in the faunas of late
Trenton and Cincinnatian time. With more research into the
Russian Heterotrypide, it is of course probable that the above notes
will require modification, but it is believed that the following fact will
remain unchanged, namely that the Baltic forms belong to the generic
types identical with those highly characteristic of the American
Black River and other North Atlantic faunas.

The Heterotrypide are amalgamate Trepostomata differing from
the Monticuliporide in having straight diaphragms instead of the
curved cystiphragms. Clearly defined, frequently large, typical
acanthopores are developed in every member of thefamily. Although
the walls of adjoining zoccia are fused, this double wall persists as a
distinct but thin unit which has a clean-cut individuality, as shown
in sections. The other two families of the Amalgamata differ from

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 205

the Heterotrypide in just these two respects. Both the Batosto-
mellide and the Constellariide have diaphragms instead of cysti-
phragms, thus differing from the Monticuliporidz, but the first men-
tioned has thick walls with a number of them so fused together that
the individual wall common to adjacent zocecia is not clearly distin-
guishable. The Constellariide differs from all the Amalgamata
families in the nature of its acanthopore, which is small and granular.

Although the family differences mentioned above are few and
apparently slight, they are known from the study of a host of species
to be fundamental and of as great value as more detailed discrimina-
tions founded upon living forms.

Genus DEKAYELLA Ulrich.

Dekayella Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 155; vol.
6, 1883, p. 90.—MitER, North Amer. Geol. and Pal., 1889, p. 184.—U.ricu,
Geol. Surv. Illinois, vol. 8, 1890, p. 372; Geol. and Nat. Hist. Surv. Minne-
sota, vol. 3, pt. 1, 1893, p. 269; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 273.—Srupson, Fourteenth Ann. Rep. State Geologist New York
for the year 1894, 1897, p. 589.—NickLes and BassteR, Bull. 173, U. 8.
Geol. Surv., 1900, p. 31.—Cumines, American Geologist, vol. 29, 1902, p.
200.—ULRicH and BassterR, Smiths. Misc. Coll., vol. 47, 1904, pp. 24, 27.

Heterotrypide with an erect ramose or frondescent zoarium made
up of rather thin-walled zocecia, usually abundant mesopores, both
kinds of tubes crossed by numerous diaphragms; acanthopores in
two sets, large and small.

The presence of two sets of acanthopores in Dekayella is the only
distinction between this genus and Heterotrypa, but as this character
pertains to a dozen or more species ranging through the middle and
upper Ordovician, it is believed to be of generic importance. The
two sets of acanthopores are distinctly visible only in the mature
zone of the zoarium, so that tangential sections which cut other parts
of the specimen will not show this feature.

Genotype.—Dekayella obscura Ulrich. Upper Ordovician (Eden) of
the Ohio Valley.

DEKAYELLA PRAENUNTIA Ulrich.
Text fig. 111.

Dekayella prenuntia Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt.
1, 1893, p. 270, pl. 23, figs. 32-37.—Smpson, Fourteenth Ann. Rep. State
Geologist of New York for the year 1894, 1897, p. 589, figs. 177-179.

The Wassalem beds at Uxnorm have afforded numerous specimens
of a Dekayella so similar to the typical D. prenuntia Ulrich, and some
of its varieties, that I am unable to point out any distinguishing
characters. Most of the Russian specimens have the characteristics
assigned to D. prenuntia var. simplex Ulrich, a form in which the
mesopores are reduced to a minimum number, the zoccial apertures

206 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

are polygonal, thick-walled, and in contact, and the acanthopores are
not as well developed as usual. Other examples, however, possess
the arrangement of acanthopores and mesopores prevailing in the
typical form of the species. The tabulation of the common Russian
form is exactly the same as shown in figure 111 f of the Minnesota
specimen, while tangential sections of both Ulrich’s species and
varieties can be duplicated in slides prepared from the European
examples. The fragment of a zoarium shown in figure 111 a@ will
illustrate the growth of the Russian specimens equally well. The
characters of D. prenuntia are as follows:

Zoarium of subcylindrical, frequently compressed, irregularly
dividing branches from 4 to 12 mm. in diameter. Surface without

Fig. 111.—DEKAYELLA PRENUNTIA AND VARIETIES. @, FRAGMENT OF A VARIETY, NATURAL SIZE; b, TAN-
GENTIAL SECTION, X18, OF THE TYPICAL FORM; C, TANGENTIAL SECTION, X18, OF VARIETY SIMPLEX; d
AND €, SMALL PORTIONS OF TWO TANGENTIAL SECTIONS, X50; /, VERTICAL SECTION, X9, OF SPECIMEN
WITH NUMEROUS MESOPORES; g, MINUTE STRUCTURE OF WALLS IN SECTIONS, X50. BLACK RIVER
(DECORAH) SHALES, MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

monticules but minutely spinulose from the acanthopores which are
about half as numerous as the zocecia. Mesopores averaging one to
a zocecium, irregularly distributed and often segregated into clusters
to form the macule. Zoccial apertures angular to rounded according
to the number of mesopores, eight to nine in 2 mm.

The characters of the typical form, as seen in tangential sections, are
illustrated in figures 111 6 and e, while the vertical section is essen-
tially as shown in figure 111 f.

Occurrence.—Not uncommon in the Wassalem beds (D3) at Uxnorm
(Cat. No. 57289, U.S.N.M.), and in the Kuckers (C2) at Reval (Cat.
No. 57290, U.S.N.M.), Esthonia. The American specimens are
abundant in the various divisions of the Black River (Decorah)
shales of Minnesota and Iowa.

British Museum, one specimen from the Wassalem beds at Uxnorm.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 207

DEKAYELLA PRZENUNTIA SIMPLEX Ulrich.
Text fig. 111.

Dekayella prenuntia var. simplex Utricu, Geol. and Nat. Hist. Surv. Minnesota,
vol. 3, pt. 1, 1893, p. 271, pl. 23, figs. 39-42.

This variety, which, as noted before, is best represented in the
Russian collections, may be distinguished from the typical form, first,
by the scarcity of mesopores, second, by its rather thick-walled,
polygonal zocecia, and third, by the few and rather poorly developed
acanthopores. The two sets of acanthopores characteristic of Dekay-
ella are distinguished with difficulty. In vertical sections, aside
from the practical absence of mesopores, no differences can be noted
between this and the typical form.

Occurrence—The American types are from the Black River
(Decorah) shales, at Minneapolis and St. Paul, Minnesota. Very
abundant in the Wassalem beds (D3) at Uxnorm, Esthonia (Cat. No.

57291, U.S.N.M.).

British Museum, specimens and thin sections from Uxnorm.

DEKAYELLA PRA NUNTIA NZ:VIGERA Ulrich.

Dekayella prenuntia var. nxvigera UtricH, Geol. and Nat. Hist. Surv. Minne-
sota, vol. 3, pt. 1, 1893, p. 271.

This form is much like the preceding variety semplex and differs
mainly in having conspicuous groups of maculz composed of numer-
ous mescpores. Other differences are thinner zoccial walls and a fre-
quently inosculating form of growth. The Russian specimens are
small fragments of zoaria and do not show such frequent branching,
but otherwise they are identical with the Minnesota forms.

Occurrence.—Rare in the Wassalem beds (D3) at Uxnorm, Esthonia
(Cat. No. 57292, U.S.N.M.). The American form was found in the
Black River (Decorah) shales of Minnesota.

British Museum, specimen and thin section from Uxnorm.

Genus LEPTOTRYPA Ulrich.

Leptotrypa Unricu, Journ. Cincinnati Soc. Nat. Hist., vol. 6, 1883, p. 158.—
Miter, North Amer. Geol. and Pal., 1889, p 311.—Uuricu, Geol. Surv.
Illinois, vol. 8, 1890, pp. 377, 455; Geol. and Nat. Hist. Surv. Minnesota,
vol. 3, pt. 1, 1893, p. 316.—Stueson, Fourteenth Ann. Rep. State Geol. New
York for the year 1894, 1897, p. 580.—NickiEs and Basster, Bull. 173, U.S.
Geol. Surv., 1900, p. 31.—Uricu and Bassizr, Smiths. Misc. Coll., vol. 47,
1904, pp. 24, 28.—Cumrines, Thirty-second Ann. Rep. Dept. Geol. Nat. Res.
Indiana, 1907, p. 749.

Heterotrypide with the zoarium of thin, evenly spread, parasitic
expansions with thin-walled, polygonal zowcia, no mesopores, few
diaphragms, and very small acanthopores, which are never abundant.

Genotype.—Leptotrypa mumma Ulrich. Upper Ordovician (Mays-
ville), Ohio Valley.

208 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

As understood at the present time, this genus has abundant repre-
sentatives in the southern Atlantic faunas of Upper Ordovician time,
but, with a single exception, no species are known in other Ordovician
formations. The exception is the Leptotrypa hexagonalis Ulrich,
known in America only in the Platteville limestone of Wisconsin
and Minnesota, but represented in the Kuckers shale (C2) of Esthonia
by numerous specimens.

LEPTOTRYPA HEXAGONALIS Ulrich.
Text figs. 112-114.

Lepiotrypa hexagonalis Utricu, Geol. Surv. Illinois, vol. 8, 1890, p. 455, pl. 36,
figs. 6, 6 a; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 317.

Original description.—Zoarium forming parasitic expansions less than 1 mm. in
thickness, spread upon Orthoceras and Hyolithes. Surface smooth. Clusters of cell

g.

A HYOLITHES; 6, SURFACE OF THE SAME, X12. MIDDLE ORDOVICIAN (PLATTEVILLE) LIMESTONE, MIN-
ERAL POINT, WISCONSIN. (AFTER ULRICH.) c, A FRAGMENT OF LIMESTONE WITH A HYOLITHES IN-
CRUSTED BY THIS DELICATE BRYOZOAN. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA. ;

apertures of almost twice the usual size are arranged in diagonally intersecting rows;
these clusters are about 3 mm. apart, measuring from center to center. Zocecia regu-
larly hexagonal in shape, sometimesa little elongated, seven, measuring longitudinally,
almost nine, diagonally, in 2 mm.; diameter of the smaller 0.2 of the larger 0.35 mm.
Acanthopores prominent on the surface when well preserved.

The usual occurrence of this species in America is as a delicate,
lace-like expansion upon shells of the pteropod Hyolithes bacont Whit-
field. ‘The occurrence in the Kuckers shale is identical, even to a
great resemblance of the incrusted pteropod to H. baconi, although
this shell is probably the form described by Eichwald as Hyolithes
striatus. ‘The internal structure of Leptotrypa hexagonalis has never
been figured and I am taking this opportunity of presenting thin sec-
tions of the type, mainly for comparison with similar sections of the
Russian form. Comparison of figures 113 and 114 will show prac-
tical identity of structure in the corresponding parts of the sections.
The size, shape, and thinness of the cells are especially similar. The
Russian specimens, however, exhibit an interesting feature which
has not been observed in the American examples. This is the occur-
rence exclusively of small, thick-walled, closely tabulated mesopore-

HARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 209

like cells on the flat side of the Hyolithes, and the restriction of the
thin-walled, ordinary zocecia to the curved portions of the shell.
A vertical section of this region of small cells is shown in the lower
half of figure 114 c, and a tangential view in figure 114d. Ordinary

a

Fig. 113.—LEPTOTRYPA HEXAGONALIS. @, TANGENTIAL SECTION OF THE AMERICAN TYPE OF THE SPECIES,
X20; THE LARGER ZOGCIA FORM PART OF A MACULA, WHILE THE MORE NUMEROUS, SMALLER CELLS ARE
OF THE ORDINARY INTERMACULAR KIND; 0, SEVERAL ZOG@CIA OF THE SAME SECTION, X30, SHOWING
THEIR SIMPLICITY OF STRUCTURE; C, VERTICAL SECTION, X20, EXHIBITING BOTH REGIONS OF THE THIN
ZOARIAL LAYER. MIDDLE ORDOVICIAN (PLATTEVILLE) LIMESTONE, MINERAL PoINT, WISCONSIN.

zocecia are wanting entirely in this area which undoubtedly repre-
sents similar thickwalled, mesopored areas at the base of the zoa-
rium in such forms as Diplotrypa bicornis. The subject of such areas
of small cells is discussed on a previous page, where it is suggested

BUEDEPR BSS a.
a wes

TICAL SECTION, X20; c, A VERTICAL SECTION, X20, PASSING THROUGH A LAYER OF ORDINARY ZOGCIA,
AND ALSO CUTTING THE CLOSELY TABULATED, MESOPORE-LIKE TUBES GROWING UPON THE FLAT SIDE OF
THE SHELL; d, TANGENTIAL SECTION, X20, THROUGH THE SMALL, THICK-WALLED CELLS. KUCKERS SHALE
(C2), BARON TOLL’S ESTATE, ESTHONIA.

that the Hyolithes shell frequently or invariably rested upon its flat
side in the mud of the sea bottom.

The internal structure is so simple that specific mention of it is
hardly necessary. ‘The strong acanthopores spoken of in the original

210 BULLETIN 17, UNITED STATES NATIONAL MUSEUM.

description are extremely shallow and frequently are not present
at all.

The delicate parasitic growth and the thin-walled, polygonal, fre-
quently hexagonal, zocecia are so distinctive of this form that there
is little likelihood of confusing it with other species.

Occurrence.—Rather rare in the Platteville limestone of Black River
age in Minnesota, Wisconsin, and Illinois. Very common in the
Kuckers shale (C2), Baron Toll’s estate, near Jewe, Esthonia. The
incrusted shells of the latter locality occur mainly in the thin limestone
layers, which, where broken, show the Hyolithes and the fractured
zoarium as shown in figure 112 ¢.

Plestotypes.—Cat. No. 57293, U.S.N.M.

Specimens and thin section from Kuckers shale, Baron Toll’s
estate, in the collections of the British Museum.

Genus STIGMATELLA Ulrich and Bassler.

Stigmatella Utricu and Basser, Smiths. Misc. Coll., vol. 47, 1904, pp. 24, 33.—
BassteR, Bull. 292, U. 8. Geol. Surv., 1906, p. 27.—Cumines, Thirty-second
Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 756.

This genus was established for a group of the Heterotrypide differ-
ing from other divisions of the family in having the walls of the zoc-
cial tubes noticeably thickened at periodic intervals, and in develop-
ing acanthopores only in these zones of thick walls. This periodic
thickening of the zoccial walls with an accompanying accelerated
development of the acanthopores has been found characteristic of a
number of Orodovician species which range in growth from the
incrusting to irregularly massive and ramose. In all other respects
these species are typical Heterotrypide. The generic name was
selected for the reason that many of the species have unusually
distinct macule or ‘“‘spots’”’ composed of mesopores distributed over
the zoarium at regular intervals. Thin sections are almost a neces-
sity for the initial determination of a species of Stigmatella, although
additional specimens of a species can readily be detected after the
first example has been sectioned. The areas of thickened walls and
numerous acanthopores undoubtedly represent repeated mature
zones in the zoarium, for it is here only that mature zoccial characters
can be observed. Mesopores may be few, indeed absent, or numer-
ous. Without sections an incrusting species without mesopores
would be confused with a Leptotrypa like L. hexagonalis figured on
page 208, but a single layer of the Stigmatella would show several
alternately thin and thick walled areas. Comparison with other
genera of the Heterotrypide might be made, but in every case the
distinct zones of Stigmatella remain the most diagnostic feature.
Another characteristic is the sparse development of diaphragms, in
which feature the genus approaches Dekayia, although differing in its
numerous mesopores. The following species include one with crenu-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 211

lated walls characteristic of the typical members of the genus, and
two others conspicuous mainly for their extravagant development
of small acanthopores indenting the zoecial cavity.

Genotype—Stigmatella crenulata Ulrich and Bassler. Earliest
Silurian (Richmond), Ohio Valley.

STIGMATELLA MASSALIS, new species.
Text fig. 115.

Zoarium, a dome-shaped or hemispheric mass, which in the type-
specimen is 40 mm. in diameter and 20mm. high. Surface smooth;

Fig. 115.—STIGMATELLA MASSALIS. @, SIDE VIEW OF THE TYPE-SPECIMEN, NATURAL SIZE; } AND Cc, TAN-
GENTIAL SECTION, X20, AND A PORTION OF THE SAME, X35, PASSING THROUGH THE ZONE IN WHICH
ACANTHOPORES ARE DEVELOPED; d, VERTICAL SECTION, X8, PASSING THROUGH TWO LAYERS OF ZOGCIA;
€,PORTION OF THE SAME SECTION, X20; f/, PART OF VERTICAL SECTION, X20, THROUGH A MACULA. KEGEL
BEDS (D2), HABBINEM, ESTHONIA.

macule inconspicuous, composed of zocecia larger than usual.
Zoccia polygonal, thin-walled, seven in 2 mm.; mesopores almost
entirely wanting; restricted to the macule when present; acantho-
pores usually few and inconspicuous at the surface.

The extreme simplicity and thinness of the zocecial walls, the clear
space or white line in the walls separating adjoining zoecia, and the

212 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

scarcity of acanthopores are brought out in tangential sections. The
tangential section represented in figures 115 6 and ¢ passes through a
zone of the zoarium where the acanthopores are best developed. In
ordinary tangential sections acanthopores are practically absent.
Such sections have few if any characters to distinguish the species
from many other Heterotrypide. In vertical sections, however,
both specific and generic characters are well shown. Figure 115 d
represents a vertical section passing through two layers of zocecia and
exhibiting several mature (a) and immature (c) zones, as well as thin
zones of accelerated acanthopore development (6). Crinkling of the
zoarial walls is likewise well shown in this figure and also in figure
115 e, which represents the mature region and part of an immature
region of a single zoecial layer. The crenulated zoccial walls give a
beaded aspect to the few mesopores which are occasionally developed
in the macule (fig. 115 f).

While Sigmatella massalis agrees in growth with a number of Ordo-
vician species, it can readily be distinguished by its polygonal, small,
thin-walled zocecia, the zonal development of acanthopores, and the
crinkling of the walls, as mentioned above.

Occurrence.—Apparently rare in the Kegel beds (D2) at Habbinem,
Esthonia.

Holotype.—Cat. No. 57294, U.S.N.M.

A fragment and thin sections of the type-specimen are in the collec-
tions of the British Museum.

STIGMATELLA INFLECTA, new species.
Text fig. 116.

This most interesting species is represented by the type and by sev-
eral additional specimens from the Orthoceras and Echinospherites
limestones at localities in the Baltic provinces. All of these exam-
ples agree in being rather irregularly rounded masses several centi-
meters in diameter, such as that shown in figure 116a. The base of
the type-specimen, which is of normal growth, is slightly concave and
covered with an obscurely marked epitheca. The other examples
have had this epithecated side so overgrown by small, thick-walled,
mesopore-like cells that it is now obscurely rounded and minutely
poriferous. Upper celluliferous side of zoartum smooth and without
conspicuous maculz, although clusters of large zocecia and more
numerous mesopores are present at regular intervals. Zocecial aper-
tures in the mature stage irregularly petaloid, due to their indentation
by numerous small acanthopores. Where an immature stage of the
zoarium is presented at the surface, the apertures are polygonal and
without acanthopores. The average zocecium is 0.33 mm. in diameter
with four to fivein 2mm. Mesopores are numerous and almost inva-
riably isolate the zowcia; they are angular, thin-walled, and fre-
quently so large that in the absence of acanthopores the zocecia and

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 213

mesopores are often practically indistinguishable. The acanthopores
are small but occur in such numbers in the mature zone that they give
a minutely spinous or granular aspect to the zoarial surface.

Thin sections show this to be a typical species of Stigmatella. Ver-
tical sections exhibit thin, slightly crenulated tubes in the immature

VA

3

Fig. 116.—STIGMATELLA INFLECTA. @, SIDE VIEW OF THE TYPE-SPECIMEN, NATURAL SIZE; b, TANGENTIAL
SECTION, X20, WITH ONLY A SMALL PORTION CUTTING THE REGION OF ACANTHOPORES; Cc, ANOTHER TAN-
GENTIAL SECTION, X20, PASSING THROUGH A WELL-DEVELOPED ZONE OF ACANTHOPORES; d, SEVERAL
ZOGCIA OF THE SAME SECTION, X40, WITH THE STRUCTURE OF THE WALLS AND ACANTHOPORES CLEARLY

SHOWN; €, VERTICAL SECTION, X20, SHOWING BOTH IMMATURE AND MATURE REGIONS. ORTHOCERAS
LIMESTONE (B3), Port KUNDA, ESTHONIA.

region. These thicken somewhat in the mature zone with the devel-
opment of numerous acanthopores. The latter region is further dis-
tinguished by haying an occasional diaphragm in the mesopores.
Tangential sections vary in appearance according to the zone which is
cut. In figure 116 b, the section passes through portions of both the

214 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

mature and immature zones and shows on the left-hand side the po-
lygonal zocecia without acanthopores surrounded by mesopores often
of so nearly the same size that there is difficulty in separating the two.
In the central part of the figure a macula of mesopores occurs, while
on the right hand side the initial development of acanthopores at the
base of a mature zone is figured. The normal occurrence of the acan-
thopores in the fully matured zone is illustrated in figures 116 c and d.

Occurrence.—Rare in the Orthoceras limestone (B3) at Port Kunda,
Esthonia, and in the Echinospherites limestone (C1) at Pulkowa and
at Archangelski on the Wolchow River, government of St. Peters-
burg.

Holotype.—Cat. No. 57295, U.S.N.M.

British Museum, two sections of the type-specimen and one speci-
men from Pulkowa.

STIGMATELLA FOORDII (Nicholson).
Text figs. 117, 118.

Callapora foordit NicHotson, in Nicholson and Lydekker, Man. Pal., vol. 1,
1889, p. 351, fig. 229.

I was fortunate enough to find a single specimen of this interesting
organism in the collections from the Kuckers shale, Baron Toll’s
estate. The species can hardly be said to have been described, and,
moreover, Nicholson gave no horizon and locality other than ‘‘Ordo-
vician rocks of Esthonia,’’ but his figured thin sections are so distinc-
tive that I have no doubt of the correctness of the present identifica-
tion. Both his remarks concerning the species and his figures are
reproduced below. In the description of his figures, I have also
copied Nicholson’s wording, although the corresponding terms used
in the present paper are inserted in brackets.

The great majority of the Monticuliporoids exhibit no radial structures in the tubes
which could be compared with the ‘‘septa” of an ordinary coral. Ina few forms, such
structures do occur, but it is doubtful if in any such instance we have to deal with
structures really developed in mesenteries, and therefore really homologous with the
“septa” of the Zoantharia. Thus in Fistulipora each autopore is provided with two
longitudinal folds, situated opposite one another, toward one end of the visceral cham-
ber. Again, in a hitherto undescribed species of Callopora each autopore is provided
with from two to five radial plications of the wall, which closely resemble the ‘‘septa”
of Tetradium, and give a characteristic floriform appearance to cross sections of the
corallites.

As may be readily imagined from the foregoing notes by Nicholson
his main object in introducing figures of Callopora foordi was to
show the occurrence in certain monticuliporoids of radial plications
closely resembling the septa of typical corals, and consequently indi-
cating the affinities of Monticulipora and its allies with the corals.
However, he failed to note that a small acanthopore is present at the
end of each fold and that the present species is therefore only an exag-
gerated case of indentation of the zoccial cavity by the acanthopore

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 215

and the wall bearing it. Less pronounced examples of this sort are

seen in the preceding Stigmatella inflecta, in Orbipora wndenta, and in
many other bryozoans not described in this volume. All gradations
may be traced from the extremely developed folds of the present
species to very simple indentations caused by the swelling of the
zocecial walls when an acanthopore is inserted; in fact, all such grada-
tions may be seen in a single specimen. Thus, in figure 118 ¢, this
portion of a tangential section passes through the basal part of a
mature region and shows no acanthopores at all in most of the zocecial
walls, and a few just beginning to indent the cavities of the tubes in
the upper third of the figure. Figure 118 b exhibits the change from
the region of no acanthopores to a zone in which they develop the
four-sided Tetradium effect illustrated by Nicholson.

The remaining figures, 118 d and 118 e, show the greatest develop-
ment of the infolded, acanthopore-bearing, zocecial wall that has

Fig. 117.—STIGMATELLA FOORDI. @, A LARGE SPECIMEN OF CALLOPORA FOORDI, OF THE NATURAL SIZE;
0, TANGENTIAL SECTION OF THE SAME, SHOWING THE PSEUDOSEPTAL FOLDS IN THE AUTOPORES [ZOGCIA],
ENLARGED TWENTY TIMES; Cc, VERTICAL SECTION OF THE SAME, SIMILARLY ENLARGED, @, AUTOPORES,
M, MESOPORES. ORDOVICIAN ROCKS OF ESTHONIA. (AFTER NICNOLSON.)

been observed. In order to show the change most clearly, the zocecial
cavities in figure 118 6 have been shaded. All of these figures are
drawn from the same tangential section which passes somewhat
obliquely through the zoarium with the result that one end cuts the
immature zone and the rest of the section passes through various
phases of the mature region.

As a description of this species has never been given, the following
diagnosis is in order:

Zoarium of small, depressed, hemispheric masses seldom over 20
mm. in diameter; basal side flat and covered with a concentrically
wrinkled epitheca, celluliferous surface smooth with clusters of larger
zocecia and more numerous mesopores at regular intervals. Zocecia
small, polygonal or petaloid, seven in 2 mm. with an average aper-
ture about 0.28 mm. in diameter. Mesopores angular, thin-walled,
and numerous enough to frequently surround the zocecia. Acantho-
pores very small, varying from two to eight to a zocecium and devel-

216 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

oped at the end of a fold of the wall which in the most mature con-
dition extends far into the zoccial cavity.

The internal structure as exhibited in tangential sections has been
discussed above and the septal folds of Nicholson shown to be the
oreatly infolded, zocecial wall bearing an acanthopore. Vertical sec-
tions are especially interesting for the reason that they exhibit the
diagnostic generic character—the zonal thickening of the walls
accompanied by an accelerated development of acanthopores. The
characters of such a section, with two successive immature and
mature zones, are shown in figure 118 a. Nicholson’s vertical section

Fig. 118.—STIGMATELLA FOORDI. @, VERTICAL SECTION, X20, PASSING THROUGH TWO LAYERS OF ZOGCIA;
b, TANGENTIAL SECTION, X20, WITH THE ZOGCIA SHADED; C, PORTION OF THE SAME SECTION, X35, WITH.
FEW ACANTHOPORES; d, ANOTHER PORTION, X35, SHOWING AN EXTREME DEVELOPMENT OF THE IN-
FOLDED ZOGCIAL WALL; €, SEVERAL ZOGCIA OF A TANGENTIAL SECTION, X50, WITH SMALL ACANTHOPORES
PLAINLY DEVELOPED AT THE ENDS OF THE INFOLDED WALLS. KUCKERS SHALE (C2), BARON TOLL’s
ESTATE, ESTHONIA.

includes only the mature region of a single zone, but the tabulation
of both sets of tubes is the same as in the original of figure 117 a.

Without careful comparison, the zocecial characters of the present
form seem almost identical with those of Stigmatella wnflecta, but the
zocecia of the latter are almost twice the diameter of the former.
Internally the two species are quite distinct, especially in the tabula-
tion. No American species with which either might be compared is
known. .

Occurrence.—Rare in the Kuckers shale (C2), Baron Toll’s estate,
near Jewe, Esthonia.

Plesiotype.-—Cat. No. 57298, U.S.N.M.

Section of figured specimen in the collections of the British Museum.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 217
STIGMATELLA CLAVIFORMIS (Ulrich).

Text fig. 119.

Leptotrypa claviformis Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 319, pl. 27, figs: 20; 21.

Among the small, massive bryozoans of the Wassalem beds are
rather numerous examples with a club-shaped zoarium which agrees
externally with the above common American form. This identifica-
tion is confirmed by thin sections which show practically no variation
in specimens from the two widely separated localities. Figures of
the American examples are given below. The following remarks are
adapted from Ulrich’s description.

Zoarium growing into simple club-shaped forms varying from the
smallest figured to one that is 23 mm. long and 1.5 to 2.5 mm. in

Fig. 119.—STIGMATELLA CLAVIFORMIS. @ AND 0, TWO OF THE CLUB-SHAPED ZOARIA, NATURAL SIZE} C,
VIEW OF ZOGCIA IN TANGENTIAL SECTION, X18; d, VERTICAL SECTION THROUGH THE MIDDLE OF A ZOA-
RIUM, X18. BLAcK RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.)

diameter. Zocecial tubes growing about the axial body very much
as in ordinary ramose forms that grow about an imaginary center;
diaphragms abundant except in the outer or direct portion; walls
thin. Zocecial apertures subangular, nearly uniform in size, there
being no appreciable clusters of large cells; without apparent arrange-
ment, about 14in 3mm. What may be mesopores, but more likely
are merely young zocecia, are scattered among the ordinary tubes.
At intervals, however, they seem to be more numerous than usual.
Many, perhaps the majority, of the angles of junction are thickened
and occupied by projecting acanthopores.

Occurrence-—Common in the various divisions of the Black River
(Decorah) shales in Minnesota and Iowa; also in the Wassalem beds
(D3) at Uxnorm, Esthonia (Cat. No. 57299, U.S.N.M.).

British Museum, one specimen from Uxnorm.

218 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Family CONSTELLARIIDA Ulrich.

Until the publication of the English edition of Zittel’s Textbook of
Paleontology, the members of this family were assigned to the
Trematoporide, a position which increasing knowledge has shown
to be unwarranted. In a general way the wall structure of Constel-
laria and its allies is similar to that obtaining in the other families of
the Amalgamata, but other characters are so different that a new
family, Constellariide, was instituted by Ulrich in the above-men-
tioned publication. The most obvious characteristic of the family
is the usually stellate shape of the macule. More important features
are the small, hollow spines or granules which occur in place of true
acanthopores, and a somewhat granular wall structure occurring in
the more mature portion of the zoarium.

The simplest type of Constellariids is believed to be expressed in
Dianulites, which, although it lacks the stellate macule, has the
characteristic granulose wall structure and the small granules or
hollow spines in place of acanthopores. Dianulites was at first
believed to be restricted to the Baltic Ordovician deposits, but a
single large typical species of the genus is now recognized in America.
Typical species of Constellaria, Stellipora, and Nicholsonella occur in
both America and Russia. The remaining genus of the family,
Idiotrypa, is known only from early Silurian rocks and has not been
noted elsewhere than in North America.

Genus CONSTELLARIA Dana.

Constellaria Dana, Zoophyta, 1846, p. 537 —NicHotson, Pal. Ohio, vol. 2, 1875,
p. 214; Pal. Tab. Corals, 1879, p. 292; Genus Monticulipora, 1881, p. 97.—
Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 156; vol. 6, 1883,
p. 265.—James and Jamzs, Journ. Cincinnati Soc. Nat. Hist., vol. 11, 1888,
p. 29.—Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 374, 423; Geol. and Nat:
Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.311; Zittel’s Textbook of Paleon-
tology (Eng. ed.), 1896, p. 276.—J. F. James, Journ. Cincinnati Soc. Nat.
Hist., vol. 18, 1896, p. 117—NickLes and Basster, Bull. 173, U. 8. Geol.
Surv., 1900, p. 34.—Cumines, Thirty-second Ann. Rep. Dep. Geol. Nat.
Res. Indiana, 1907, p. 742.

Stellipora MitnNE-Epwarps, Hist. Nat. des Corall, vol. 3, 1860, p. 281.

Stellipora (part) DyBowsx1, Die Chaetetiden d. Ostbalt. Silur-Form., 1877, p. 42.

The generic characters of this group of Bryozoa have been worked
out and described by Ulrich in his various memoirs. The genus is
one of the most easily recognized of Ordovician and early Silurian
types, mainly on account of the very characteristic star-shaped
macule. This, although the most obvious feature, is no more impor-
tant than the erect ramose or frondescent growth and the minute
structure of the walls. Nickles and Bassler have briefly defined the
genus as follows:

Zoarium growing into erect, flattened branches or fronds from a basal expansion
which is attached to foreign bodies; surface with depressed stellate macule, the

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 219

spaces between the rays elevated and occupied by two or three short rows or clusters
of closely approximated apertures; mesopores aggregated into macule, internally
with gradually crowding diaphragms.

Genotype.—Ceriopora constellata (Van Cleve) Dana. Upper Ordo-
vician of the Ohio Valley.

CONSTELLARIA VARIA Ulrich.
Text figs. 120-122.

Constellaria varia Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 311, pl. 21, figs. 1-7.

Several well-preserved specimens of a ramose species of Constellaria
from the Jewe limestone (D1) and Wassalem beds (D3) proved upon

uiO Cie: 0%
Age fan
ches Ls

a

o> “,
iat

BR
ia aM
ey

Fic. 120.—CoNSTELLARIA VARIA. @, FRAGMENT OF A ZOARIUM, NATURAL SIZE; 6, SURFACE OF A MATURE
SPECIMEN, X9; c, TANGENTIAL SECTION, X18; d, SMALL PORTION OF THE SAME, X50, WITH TWO MURAL
TUBULI; €, VERTICAL SECTION OF AVERAGE EXAMPLE, X18. NEMATOPORA BED OF TRENTON, NEAR
CANNON FALLS, MINNESOTA. (AFTER ULRICH.)

careful comparison with the American form to be identical with the
well-marked Constellaria varia Ulrich from the Lower Trenton strata
of Minnesota and other States. Figure 120 represents the external
and internal features of the American type and will serve equally
well for the identification of the Russian specimens. The internal
characters of a well-developed specimen from Uxnorm are shown in
figure 121. Comparing this with the corresponding figures of the
American form, the tangential sections are seen to be practically
identical, while the slight difference in the vertical sections is due
solely to the greater development of the mature region in the Russian
specimens. The figured vertical section passes through a macula,
and thus gives the appearance of a greater development of mesopores.
Ulrich’s description of the species is quoted below.

Zoarium consisting of one or more irregularly dividing branches arising from a
broad basal expansion. Branches usually compressed, generally from 8 to 10 mm.
wide, but varying between the extremes of 3and 15mm. Macule large, irregularly

92602°—Bull. 77—11 16

220 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

stellate, very slightly depressed or on a level with the general plane of the surface.
The small clusters of zocecial apertures (4 to 10 in each) occupying the angles
between the rays may be elevated a little above the level of the maculez, but as a
tule the entire surface may be said to be even. Ina few cases, however, the maculz
a

aay.

(as , iy

Fig. 121.—CoONSTELLARIA VARIA. @, TANGENTIAL SECTION, X20, CUTTING SEVERAL RAYS OF A MACULA;
b, VERTICAL SECTION, X20, PASSING THROUGH A MACULA. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

themselves are higher than the spaces separating them. Zocecial apertures subcir-
cular, inclosed by a very thin rim, and varying considerably in size, though approxi-
mately equal on each fragment. Width of interspaces varying correspondingly, so

ey) PE ai
= j ; : 2

; || [Pp [con
THR

HIN
nin ¥ \ ; Ag

mV LLY

Fic. 122.—CONSTELLARIA VARIA. @, VERTICAL SECTION, X20, OF A SMALL EXAMPLE; 0, TRANSVERSE |

SECTION OF THE SAME SPECIMEN, X20. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

that about the same number of apertures occur in a given space in all specimens.
Ten or 11 occur in 3 mm. in the intermacular spaces, while the diameter of the
apertures varies between the extremes of 0.15 and 0.25 mm.

The smooth, ramose zoarium and the well-marked stellate maculz
of Consiellaria varia are so different from associated forms that no
confusion is likely. .

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 221

Occurrence.—The original types of Constellaria varia were found in
the Nematopora bed of the Lower Trenton at Cannon Falls, Minne-
sota. The species is known from the same general horizon at other
American localities, notably in Canada and in Tennessee. In the
Russian collections from the Wassalem beds (D3), at Uxnorm, near
Reval, a fine, practically complete zoarium of this species occurred,
while smaller but equally typical specimens were found in the Jewe
limestone (D1), Baron Toll’s estate, near Jewe, Esthonia.

Plesiotypes.—Cat. Nos. 57300, 57301, U.S.N.M.

British Museum, thin section of a Russian figured specimen.

Genus STELLIPORA Hall.

Stellipora Hatt, Nat. Hist. New York, vol. 1, 1847, p. 79 —D’Orpieny, Prodr.
de Pal., vol. 1, 1850, p. 22.—Utricu, Journ. Cincinnati Soc. Nat. Hist., vol.
5, 1882, p. 155; vol. 6, 1883, p. 263; Geol. Surv. Illinois, vol. 8, 1890, p. 374;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 276.—NicKLES and
Bass er, Bull. 173, U. 8. Geol. Surv., 1900, p. 34.

Stellipora (part) DyBowsx1, Die Onacteiden d. Ostbaltischen SiturcHGawe moss,
p. 42.—MueEr, North Amer. Geol. and Pal., 1889, p. 203.

Differs from Constellaria in its incrusting or free lamellate method
of growth and in having the interspaces between the raised zocecial
clusters composed of mesopores alone.

Genotype.—Stellipora antheloridea Hall. Middle Ordovician (Tren-
ton) of New York and Canada.

From America but a single species of Stellipora, the genotype, has
been described, although the collection of the United States National
Museum contains several new forms allied to the Russian species.
A review of Dybowski’s work upon this genus has shown that, while
he included Constellaria as a synonym, the two species assigned 'to
Stellupora are typical members of the latter genus as now restricted.
The third species noted below is interesting in that it forms large,
isolated, star-like clusters. With the genotype, the several new
American forms, and the three species following, Stellipora has a fair
specific representation.

STELLIPORA REVALENSIS Dybowski.

Plate 4, figs. 8-80; text fig. 123.

Stellipora revalensis DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-Forma-
tion, 1877, p. 44, pl. 3, figs. 8a, b.

Both this and the following species have been described in detail by
Dybowski, and J can only verify their reference to Stellapora and add
a few notes concerning the specific characters. There are no described
American forms with which either might be confused. In each spe-
cies the zoarlum is a small, lamellate expansion with a wrinkled
epitheca on the basal side, and with prominent star-shaped clusters

2292 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

as the most conspicuous feature of the celluliferous face. In S.
revalensis these clusters are outlined by polygonal, raised areas com-
posed of mesopores (see pl. 4, fig. 8), but in 8. constellata these thin
ridges are absent, the rays of the maculz being confluent. The occur-
rence of such polygonal areas is not restricted to Stellipora because
species of Constellaria, such as C. polystomella, and of Dianulites, D.
petropolitana for example, likewise bear them. Numerous specimens
of the two latter species have been examined with the result that the
polygonal areas are known to be inconstant in their development.
Some specimens have them excellently developed, while others show
no trace. Still other examples will have a portion of the surface with
well marked areas, and another portion without a trace of them.

Fig. 123.—STELLIPORA REVALENSIS. @, VERTICAL SECTION, X20; 6, TANGENTIAL SECTION, X20, ILLUS:
TRATING SERUCTURE OF TWO RAYS OF A CLUSTER. KUCKERS SHALE (C2), BARON TOLL’S ESTATE,
ESTHONIA.

These thin ridges are composed entirely of mesopores and seem to
mark out areas of distinct growth.

In figure 123 the normal internal structure, drawn under the
camera lucida, is shown. Figure 123 a represents the very short
immature zone in which the zoccia are prostrate, and the mature
region of the ordinary zocecia and a part of a macula. Dybowski’s
figure of the vertical section is rather diagrammatic and fails to show
the cyst-like tabule filling the mesopores. The zocecia proper have
straight diaphragms about their own diameter apart in the more
crowded portions. Comparing the figure on plate 4 and figure 123,
Dybowski’s tangential section and the one prepared from specimens
in the collection of the United States National Museum are seen to
be alike. The small, rounded apertures are the zoccia, while the
jarge, irregularly shaped openings represent the mesopores.

Further notes upon Stellipora revalensis are given under the discus-
sion of the next species.

Occurrence.—Dybowski records his species from zone 1 at Sack,
Kuckers, and Reval. The specimens before me come from the

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 223

Kuckers shale (C2), Baron Toll’s estate, near Jewe, and from Reval,
Esthonia.

Plesiotype.—Cat. No. 57302, U.S.N.M.

British Museum, one thin section from the Kuckers shale, Baron

Toll’s estate.
STELLIPORA CONSTELLATA Dybowski.

Plate 4, figs. 9, 9a.

Stellipora constellata DyBowsxt, Die Chaetetiden der Ostbaltischen Silur-For-
mation, 1877, p. 48, pl. 3, figs. 9, 9a.

I have not encountered this species in the collections studied and
must therefore limit my remarks to Dybowski’s description and fig-
ures. According to that author, the zoarium is lamellate and made
up of star-shaped clusters 6 to 8 mm. in diameter and 2 to 3 mm. dis-
tant from each other. Each star consists of
five to eight elongate, spindle-shaped, rhom-
boidal elevations arranged radially. The
clusters have no polygonal areas segregat-
ing them, but are arranged sometimes so
closely that the radii become confluent.

Dybowski’s illustration of the internal
structure is sufficient to show this species to
be a typical Stellupora and closely related to
the preceding S. revalensis. Indeed, it is rs

: . ° . Fig. 124—STELLIPORA APSENDE-
possible that they are identical species, the ~ somns. A zoarrum, x3, aT
main difference being the occurrence of thin —TCHED 70 AsPECIMEN or ECHIN-

° ° OSPHERITES. ECHINOSPHERITES
polygonal raised areas surrounding the insstonz (Ci), Reval,
macule in S. revalensis. As remarked be- Fst#onu.
fore, this occurrence is not always constant in a species and the
type of S. constellata may have happened to be without them.

Occurrence.—According to Dybowski, the species occurs in his
zone 2 at Hohenholm on the island of Dago. If in place, the specimen
would probably have come from the Lyckholm limestone (F1)

STELLIPORA APSENDESOIDES, new species.
Text fig. 124.

Zoarium a single, incrusting, rounded cluster of zocecia and meso-
pores, 6.5 mm. in diameter and less than a millimeter thick. Surface
exhibiting 12 radially arranged, sharply elevated, thin ridges bearing
small, subcircular zocecia, 0.13 mm. in diameter. Depressed areas
between the crests occupied by large, angular mesopores which are
closed at the surface in mature specimens. In thin sections the usual
characters of Stellapora, such as shown in S. revalensis, are indicated.

Externally the zoarium has quite a resemblance to the Mesozoic
genus Apsendesia, as suggested in the specific name, but internally
the two are quite distinct. The fact that the growth consists of a

224. BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

single cluster or macula will distinguish the species from other Stelli-
poras and also other Russian bryozoans save Scenellopora socialis
(Kichwald). The zoccia of the latter are so different in shape and
arrangement that no confusion should arise. Of American forms,
the one nearest to S. apsendesoides is a new species or variety from
‘the Black River shales of Minnesota, having the same method of
growth and differing only in its smaller zoartum with fewer and less
sharply raised rays.

Occurrence.—Rare in the Echinospherites limestone (C1) at the
Red Light House, Reval, Esthonia.

isin aye One. No. 57304, U.S.N:M.

Genus NICHOLSONELLA Ulrich.

Nicholsonella Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 374, 421; Geol. and
Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 313; Zittel’s Textbook
of Paleontology (Eng. ed.), 1896, p. 276.—Simpson, Fourteenth Ann. Rep.
State Geologist of New York for the year 1894, 1897, p. 590.—NicKkEs and
BassLER, Bull. 173, U. S. Geol. Surv., 1900, p. 34.—Basster, Bull. 292,
U. S. Geol. Surv., 1906, p. 37.—Cumines, Thirty-second Ann. Rep. Dep.
Geol. Nat. Res. Indiana, 1907, p. 751.

Species of Micholsonella are readily recognized in thin sections
by the presence of a granular, calcareous deposit in the outer part
of the mature zone, filling the interzowcial spaces and obscuring
the walls of the mesopores. The walls of both zocecia and meso-
pores are traversed longitudinally by minute tubuli, which, in
tangential sections and at the surface appear as granular, acantho-
pore-like structures. Somewhat similar granular structures are
present in Constellaria with which Nicholsonella is believed to be
allied, although the absence of such distinct, star-shaped maculee
in the latter is an easy means of separation. The following well
marked species has characters quite different from any known
American form of Nicholsonella but there seems to be no reason
for not referring it to the genus.

Genotype.—Nicholsonella ponderosa Ultich. Middle Ordovician
(Black River) of Illinois and Minnesota.

NICHOLSONELLA GIBBOSA, new species.

Plate 11, figs. 1-6; text figs. 125, 126.

Cir. Heteropora gibbosa EicHwaiD, Lethza Rossica, vol. 1, 1860, p. 419, pl. 26,
figs. 6 a, b.

Zoarium of small masses varying in shape from regular hemi-
spheric forms with a flat or slightly concave concentrically wrinkled
base, to irregular, elongated or nodulated lumps. The regular
hemispheric zoaria occur most often and are usually about 15 mm.
in diameter and 6 or 7mm. high. Continued growth in one direction
gives rise to forms several centimeters long and a centimeter or

“EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 225

less in diameter, while the irregular nodular masses are the result
of either interrupted growth or of accelerated growth in several
directions. The zoarial surface in all the

: : : b
various forms of growth is usually smooth, atin:
but in rare instances the macule are indi- ste =,

cated by slightly elevated, dome-shaped e: ast
e e easy a oad =
areas, 3 mm. apart, measuring from their nl
: c : Fig. 125.—NICHOLSONELLA GIBBOSA.
respective centers. Ordinarily the macular — gienwaiv’s meurrs or Hxrer-
zocecia, and mesopores differ so little from ©POBA GIBBosA; 4, ZoaRIUM,
= NATURAL SIZE; 6, THE SURFACE
the ordinary forms that the macule are — entarcen. “Catcame A ORTHO-
indistinguishable at the surface. Zocecial C#84™T#S,’ PULKowA, GovERN-
A MENT OF ST. PETERSBURG.
apertures direct, polygonal to rounded, four
in 2 mm., completely isolated by numerous small, angular mesopores.
In old examples the walls of both zocecia and mesopores bear
numerous small granules.

Fig. 126.—NICHOLSONELLA GIBBOSA. @ AND 6, TOP VIEWS OF TWO IRREGULAR ZOARIA, NATURAL SIZE;
C, SIDE VIEW OF A THIRD SPECIMEN OF MORE REGULAR FORM; d, AN EXAMPLE WITH LOW MONTICULES,
VIEWED FROM ABOVE; €, TANGENTIAL SECTION, X20, THROUGH A MACULA; f, PORTION OF THE SAME
SECTION, X20, CUTTING THE ORDINARY ZOGCIA; g, SEVERAL ZOG@CIA, X40, ILLUSTRATING THE MINUTE
STRUCTURE; h, VERTICAL SECTION, X8; 7, PORTION OF THE SAME SECTION, X20. GLAUCONITE LIMESTONE
(B2), REVAL, ESTHONIA.

As usual in species of the genus, the internal structure of the pres-

ent form, with regard to clearness of preservation, is in sharp contrast
with associated Trepostomata. Numerous thin sections of the

226 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

best preserved specimens have been prepared, and all agree in the
characters here illustrated. In vertical sections the zoccial walls
are thin, slightly crenulated, and only occasionally show as definite
sharp lines, usually being represented by a diffuse granular structure.
The mesopores differ from the zoccia only in size and in being
possibly more granular in structure. Diaphragms are few in both
sets of tubes, the average number in each being represented in the
figured vertical sections. Tangential sections show the same indefi-
nite wall structure, and, in addition, exhibit numerous granular
structures, possibly representing acanthopores, in the most mature
region.

The species described by EHichwald as Heteropora gibbosa from
the Orthoceras limestone at Puikowa, appears to be based upon a
monticulated zoartum of the present form. Without an examina-
tion of Eichwald’s type the matter of course can not be settled defi-
nitely, but in order to avoid a possible synonym, I have given the
form here described the same specific name.

The small, massive zoarium with rather large zoccia isolated by
minute mesopores, and the numerous granules of the surface are
external characters which alone will identify the species. Internally
the structure is too different from any other form to require com-
parison.

Occurrence—Abundant in the Glauconite limestone (B2) at Reval
and vicinity, in Esthonia, and at Pawlovsk, Tswos, on the Wolchow
River, localities on the Ladoga Canal, and Wassilkowa, government
of St. Petersburg; in the Orthoceras limestone (B3), at Pawlovsk,
and in the Echinospherites limestone (C1), 4 miles east of Reval,
Esthonia.

Cotypes.—Cat. Nos. 57305 to 57313, U.S.N.M.

British Museum, specimens and thin sections from the Glauconite
limestone, Reval.

Genus DIANULITES Eichwald.

Dianulites Etcowatp, Zool. Spec., vol. 1, 1829, p. 180; Letheea Rossica, vol.
1, 1860, p. 487.—DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 14.—NicHotson, Genus Monticulipora, 1881, pp. 20,
155.—WAAGEN and WENTZEL, Pal. Indica, ser. 13, 1886, p. 874.—Simpson,
Fourteenth Ann. Rep. State Geol. New York for the year 1894, 1897, p.
587.—NIcKLES and BassuER, Bull. 173, U. 8. Geol. Surv., 1900, p. 230.

Hevaporites PANDER, Beitr. zur Geogn. d. russ. Reichs., 1830, p. 106, pl. 1, fig.
5; pl. 28, fig. 8.

Although this name has been frequently quoted, the status of
the genus is indicated by the following note published by Nickles
and Bassler in their Synopsis of American Fossil Bryozoa: *

1 Bull. 173, U. S. Geol. Surv., 1900, p. 231.

Ee

‘EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 227

This genus as defined by Eichwald is wholly unintelligible and was, until 1877,
when Dybowski resurrected and redefined it, not recognized by paleontologists.
Dybowski has not helped the matter by his effort, for his arrangement of the species
is quite arbitrary, no two forms perhaps being strictly congeneric.

The only observations of any value at all that have been published
concerning the generic characters of Dianulites are those by Dybowski
and by Nicholson. Dybowski retained the genus for those monticuli-
poroids in which the zoarium was massive or ramose, and consisted
of large, thin-walled, tabulated zocecia im contact with each other
on all sides. As expressed in Dybowski’s generic synopsis, Dianu-
lites would include all forms which have no ‘‘coenenchyma”’ (inter-
stitial cells), but do not possess tabulze in the tubes, which, in addition,
are comparatively large and thin walled. Although this limitation
of the genus was a distinct advance upon any previous work, still
such generic characters were of so little value that, according to
present-day studies, Dybowski assigned representatives of at least
four other genera to Dianulites. Nicholson, in discussing the sub-
genus Diplotrypa’ calls attention to a possible identity between
Diplotrypa and Dianulites. However, he rejects the latter name
entirely, first, because the generic diagnosis of Eichwald is unrecog-
nizable, and, second, because the genus, as resurrected by Dybowski,
is unmistakably not a natural group.

The first species referred by Hichwald to Dianulites was either D.
detritus or D. fastigiatus, both of which were described on the same
page. Later? he distinctly refers to D. detritus as the type species
and gives good figures of both D. detritus and D. fastigiatus.. The
ulustrations of these two forms are clearly of the same species, and
their identity was recognized by Dybowski, who, however, figures
and describes the species as D. fastigiatus. As I have not had the
opportunity of consulting the original publication, and as Dybowski
was probably able to do so, I have accepted the specific name fastigi-
aius for the genotype. Since both names apply to the same form,
the matter is of little consequence.

The external features of Dianulites fastigiatus are so unique that a
study of the internal structure is not necessary to determine the
species. Indeed, the merest tyro could identify the species from
Eichwald’s figures, one of which shows clearly that the zocwcia are
completely isolated by mesopores. The occurrence of numerous
mesopores is corroborated by thin sections, and yet Dybowski laid
stress upon the absence of mesopores, or, in his words, the absence of
coenenchyma, as a generic character.

After studying specimens of Dianulites fastigiatus from six Russian
and Swedish localities, I find that this species, as well as a number of

1 Genus Monticulipora, 1881, p. 155.
2 Lethzea Rossica, vol. 1, 1860, p. 487, pl. 28, figs. 8, 9. —

228 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

American and European forms, have characters in common which
fully justify the recognition of a distinct genus. Although Dianu-
lites could not hitherto be regarded as a valid genus, the name is still
available, and I propose to retain it with the charaeters presented
by the genotype D. fastigiatus.

Generic cagnosis. —Zoarium massive, elongate, bluntly turbinate
in the type species, solid and hemispheric in other forms; basal surface
covered with an epitheca. As in most other Eoniicaline aie
macule are present, either as groups of larger cells opening on a plane
with the other zoccia, or as clusters of both large and small zoecia
arising into monticules. Zocecia polygonal, thin-walled, separated
by numerous mesopores as in the type species, or with mesopores few
and, im some cases, practically absent. Acanthopores absent but
numerous small granules may be observed on the zocecial walls at the
surface and in thin tangential sections cutting the oldest part of the
peripheral region. Walls of zocecia amalgamated and showing little
structure beyond the granules just mentioned. In fractures the zoc-
cial tubes break unevenly across or through the walls instead of part-
ing between them as in most associated Trepostomata. This style
of rough fracture results in a vitreous or crystallme appearance which
has been found most characteristic of this and related genera. Dia-
phragms always present but varyimg in number in the different
species.

Genotype.—Dianulites fastigiatus Eichwald. Middle Ordovician of
Russia and Sweden.

Thin sections show a whats structure of the walls that is unlike
all other bryozoan genera save Nicholsonella. In vertical sections
the otherwise structureless walls sometimes present an obscure
lineation arranged vertically. Tangential sections show this lineation
to be due to minute column-like granulose structures composed of
darker calcite. In such a section, a wall with the structure well
preserved will, therefore, be made up of alternating light and dark
spots. This appearance has been observed in an American species,
Monotrypa (?Chaetetes) cumulata, from the Trenton group of Minne-
sota. Ulrich noted its peculiarity of structure, but believed that it
might be due to secondary causes, and therefore hesitated in referrmg
the species to Chaetetes, with which genus the column-like structure
in the walls seemed to ally it. With only a single species at hand,
this hesitancy on his part was only natural, but with numerous exam-
ples of the four species here described in addition, and also their great
differences in geologic and geographic occurrence, I am convinced that
the peculiarities are structural and not due to preservation. Con-
cerning the relation of Dianulites to Chaetetes, I am at present unable
to discuss the subject further than to express the opinion that careful
work on the latter genus will show it to be distinct, although possibly
allied to the former.

ey

'BARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 229

In the above diagnosis I have endeavored to give all of the generic
features, although it is recognized that some of these pertain equally
well to other genera. The massive zoarium of thin-walled, angular
zocecia, without acanthopores, occurs in a number of totally unre-
lated genera, but these features, in connection with the peculiar
glassy-like internal structure, and the occurrence of numerous small
eranules or tubular structure in the walls, form a combination of
characters duplicated in part in only one other group, namely, the
peculiar Ordovician genus Micholsonella. This latter genus has al-
ways been regarded as of uncertain affinities because of its unusual
internal structure. Its zoaria vary from ramose or flattened branches
to free or incrusting expansions externally much like other monticuli-
poroids. However, the internal characters of species referred here
have always seemed so obscure and ill-defined that, until recently,
specimens of Nicholsonella have been regarded as habitually poorly
preserved and invariably unsuited for careful microscopic examina-
tion. Like Dianulites, its tube walls are thin and in the mature zone,
traversed longitudinally by minute tubules which appear at the sur-
face and in tangential sections as granules. Acanthopores are absent,
the distribution of tubules and mesopores is the same in the two, but,
unlike Dianulites, the mesopores in the mature zone of Nicholsonella
become entirely closed by a perforated calcareous deposit which ob-
scures the characters in this part of the zoarium most effectually.

Compared with Nicholsonella, Dianulites differs, therefore, mainly
in its prevailingly massive zoarium, more simple zocecial structure,
and in the absence of a calcareous deposit filling the mature portion of
the mesopores.

Hexaporites was the name given to a condition of Dianulites petropo-
litana and has no standing. Further remarks upon this name are
given under the discussion of that species.

DIANULITES FASTIGIATUS Eichwald.
Plate 2, figs. 1-3; text figs. 127, 128.

Dianulites fastigiatus EicHwaup, Zool. Spec., vol. 1, 1829, p. 181; Lethza Ros-
sica, vol. 1, 1860, p. 488, pl. 28, fig. 9 -DyBowskx1, Die Chaetetiden der Ost-
baltischen Silur-Formation, 1877, p. 20, pl. 1, figs. 1-3.

Zoarium a turbinate mass with the lower end rounded or truncated,
and the upper end, which alone bears the openings of the zoecia, flat
or slightly concave. The sides and lower portion are covered with
an epitheca, which, though sometimes smooth, is more often marked
by concentric rings or lines of growth. An average example attains
the size shown in figure 127 a, but inverted, cone-shaped specimens
only a centimeter high have been observed. An entire zoarium is
composed of numerous layers of zocecia arranged so evenly upon each
other that there often is no break between the zocecial tubes of separate
growths. Celluliferous surface smooth; macule composed of larger

930 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

zocecia and more numerous mesopores present at regular intervals
but not conspicuous. The shape of the zoarium is well shown by
Kichwald’s figure here reproduced.

Zocecia and mesopores often similar in shape and size, each with
thin walls and polygonal apertures. The zoccial apertures, however,
are usually more regularly polygonal and slightly larger than the
mesopores which frequently are numerous enough to completely
isolate neighboring zocecia. Another distinguishing character between
the two at the surface is the frequent occurrence of covers on the
mesopores, the last diaphragm in this case serving as a closure. True

Fig. 127.—DIANULITES FASTIGIATUS. @, SIDE VIEW OF A ZOARIUM, SHOWING THE EPITHECA; 6, TOP OR
CELLULIFEROUS SURFACE, ENLARGED; C, EDGE VIEW OF A BROKEN FRAGMENT, ENLARGED, ILLUSTRATING
THE UNEVEN FRACTURE; d, THE TYPE-SPECIMEN OF DIANULITES DETRITUS EICHWALD, NATURAL SIZE.
“CALCAIRE A ORTHOCERATITES,’’ REVAL (FIG. a), AND PULKOWA (FIG. d), BALTIC Russia. (AFTER
EICHWALD.)

acanthopores absent, but the granular structure characteristic of the
genus is well marked.

The similarity of the zocecia and mesopores is equally great in thin
sections. In vertical sections the wall structure of the two is the
same and their diameter is frequently equal. There need be no
difficulty in distinguishing the two, however, since diaphragms are
practically absent in the zocecia but occur always in the mesopores at
intervals varying from two to five times their own diameter.

The differences between the zocecia and mesopores at the surface,
mentioned above, hold in tangential sections, but here another means
of distinguishing them is presented. The zocecial cavities being
practically without diaphragms, are very frequently filled with clay,
the dark color of which, in sections, is in contrast with the clear calcite
filling the diaphragm-bearing mesopores.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 231

The average zocecium is 0.35 mm. in diameter, but the large aper-
tures of those in the macule attain a size half again as great. Count-
ing the intervening mesopores, three to four zocecia occur in 2 mm.
The minute structure of the walls in both sections has been described
under the diagnosis of the genus. The glassy aspect of the material
composing the zoartum and the rough fracture of the tubes has also

a

Fic. 128.—DIANULITES FASTIGIATUS. @, VERTICAL SECTION, X9, WITH DIAPHRAGMS IN THE MESOPORES
ONLY; 6, PART OF THE SAME SECTION, X20, SHOWING THE WALL STRUCTURE; c, TANGENTIAL SECTION, X20,
WITH THE ZOGCIA SHADED TO DISTINGUISH THEM FROM THE MESOPORES; d, ANOTHER PART OF THE SAME
SECTION, X40, ILLUSTRATING THE MICROSCOPIC STRUCTURE OF THE WALLS. ECHINOSPHERITES LIME-
STONE (C1), DUBOVIKI, ON THE WOLCHOW RIVER, GOVERNMENT OF ST. PETERSBURG.

been noted and is particularly evident in D. fastigiatus. The walls of
both zocecia and mesopores are gently undulating.

Dybowski’s figures of the internal structure (pl. 2, figs. 1-3),
although probably derived in part from thin sections of the species,
are misleading in that he considered all of the subequal apertures to
be zowcia. The tabulation shown in figure 3 is undoubtedly taken
from a section of another species, but the minute structure of the
walls, as indicated in figure 1, is correct.

Compared with other members of the genus, the turbinate shape of
the zoarium and the numerous large mesopores are alone sufficient to

232 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

distinguish the present form. Massive bryozoans of other genera
in the Russian Ordovician lack the vitreous substance and rough
fracture of D. fastignatus, and therefore will not be confused.
Occurrence.—The specimens in the collections of the United States
National Museum were derived from the Echinospherites limestone
(C1) at Duboviki, on the Wolchow River, Katlino and Gastilizy,

and in the Glauconite limestone (B2) at Pulkowa and Pawlovsk in -

the government of St. Petersburg, and from the Chasmops limestone,
south of Bédahamn, island of Oeland, Sweden. The additional
localities, Erras, Reval, and Baltischport, are recorded by Dybowski.
Plesiotypes.—Cat. Nos. 57334 to 57338, U.S.N.M.
Thin sections of the figured specimen from Duboviki, and speci-
mens from the Chasmops limestone, Oeland, are in the collections
of the British Museum.

DIANULITES PETROPOLITANA Dybowski.
Plate 2, figs. 4-6a; plate 10, figs. 7-11; text figs. 129-132.

Dianulites petropolitana DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 24, pl. 1, figs. 4 and 5.

Hexaporites PANDER, Beitr. zur Geogn. d. russ. Reiches., 1830, p. 106, pl. 1, fig.
5; pl. 28, fig. 8

Hexaporites fungiformis. LEUCHTENBERG in Eichwald Geognosie de Russ., 1846,
p- 370.—EicHwa.p, Letheea Rossica, vol. 1, 1860, p. 478.

Dianulites petropolitanus var. hexaporites DyBowsk1, Die Chaetetiden der Ost-
baltischen Silur-Formation, 1877, p. 30, pl. 1, figs. 6, 6a.

Monotrypa (Chxtetes?) cumulata Utricu, Geol. and Nat. Hist. Surv. Minnesota,
vol. 3, pt. 1, 1893, p. 307, pl. 27, figs. 26, 27.

The following may be included, at least in part, in the present —

species:

Millepora hemispherica (part) E1cowap, Inter ingrica et de trilob. observat.,
1825, p. 21.

Favosites petropolitanus PanpER, Beitr. zur Geogn. d. russ. Reiches., 1830, p.
105, pl. 1, figs. 7-11.

Favosites hemisphericum Kutorea, Beitr. zur Paleontologie und Geogn. Dor-
pats, 1837, p. 40, pl. 9, fig. 3.

Calamopora fibrosa E1cHWALD, Silur. syst. in Ehstl., 1840, p. 197.

Chetetes petropolitanus LONSDALE, in Murchison, Verneuil, and Keyserling, Rus-
sia and Ural, vol. 1, 1845, p. 596, pl. A, fig. 10—Knryseruine, Reise in d.
Petschoraland, 1846, p. 180.—D’ Onno Prodr. de Pal., vol. 1, 1850, p.
25.—EDWARDS and econ Mon. des Pol. foss., 1852, p. 263.

Monticulipora petropolitana Epwarps and HaIme, Brit. Foss. Cor., 1854, p. 264.—
Scumipt, Archiv fur Naturk. Liv., Ehst. u. Kurlands, vol. 2, ser. 1, 1858,
p. 228.

Not Diplotrypa petropolitana NicHOLsoN.

Hemispheric bryozoans from the Paleozoic rocks of many parts of
the world have been described and frequently cited in the literature
under the specific name of petropolitana because of the belief that
they were identical with Pander’s Favosites petropohicnus. To-day

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 233

the confusion that this has caused is.so great that in most cases it is
best to disregard such references altogether. In the above list but
a single reference to petropolitana is of undoubted value, and only the
work of those authors who might have included the species here
described as Dianulites petropolitana is cited. More than a dozen of

§

st
y

i }
Pin ee ‘
emt OE alas eed OO ete DW

Fic. 129.—DIANULITES PETROPOLITANA. a, THE TYPICAL FORM OF THE SPECIES AS SEEN IN TANGENTIAL
SECTION, 20; 6, VERTICAL SECTION, 8, SHOWING DISTRIBUTION OF DIAPHRAGMS, ¢, SEVERAL TUBES
OF THE SAME, X20, WITH THE MINUTE STRUCTURE MORE CLEARLY EXHIBITED. GLAUCONITE LIMESTONE

(B2), DUBOVIKI, GOVERNMENT OF ST. PETERSBURG.

the Russian Ordovician trepostomatous bryozoans have the zoarial
shape of this species, so, without a knowledge of the minute structure,
it is obviously impossible to determine which particular one Pander, or
any of the other authors except Dybowski, had in mind. Indeed, it
is most probable that they included a number of distinct species in

their descriptions.

934 ~- BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

As stated under the discussion of Diplotrypa, Nicholson described
and illustrated the minute structure of hemispheric specimens from
the Chasmops limestone of Sweden as Diplotrypa petropolitana, in the
belief that they were identical with Pander’s Favosites petropolitanus.
Dybowski’s conception of Pander’s species, published several years
previously, was totally different. In fact, the two are now known to
belong not only to different genera but also to distinct families.
Since both Nicholson’s Diplotrypa petropolitana and Dybowski’s
Dianulites petropolitana are sufficiently figured and described to

Fig. 120.—DIANULITES PETROPOLITANA. @, TANGENTIAL SECTION OF THE FORM «(HX APORITES,” X20,
WITH THE USUAL NUMBER OF MESOPORES; 0, SMALL PORTION OF THE SAME, X35, SHOWING GRANULES;
€, SEVERAL ZOG@CIA OF A TANGENTIAL SECTION, X35, IN WHICH CRYSTALLIZATION HAS PARTLY DESTROYED
THE STRUCTURE; d, VERTICAL SECTION, X8, PASSING THROUGH A MACULA. GLAUCONITE LIMESTONE
(B2), TSWOS, ON THE WOLCHOW RIVER, GOVERNMENT OF ST. PETERSBURG.

prevent any doubt regarding them, I have recognized this specific

name as a distinct species under each genus, without regard to the

fact that each author thought he was redefining Pander’s species.
My study of a large collection of Russian and Swedish hemispherie
forms, and of Dybowski’s description and illustrations, has convinced
me that he had in mind a very common massive species with thin-
walled, polygonal zocecia, few mesopores, diaphragms a tube diam-
eter or more apart, and, finally, the wall structure of Dianulites
fastiguatus. The fact that he regarded Pander’s Hexaporites, or, as
Von Leuchtenberg named it, Hexaporites fungiformis, as a variety of
D. petropolitana, is further evidence to me of the correctness of this

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 235

identification. Variety hexaporites, from its description and illus-
trations, and from numerous specimens before me, refers, so far as
my knowledge goes, to only one bryozoan—a form of Dianulites
petropohitana in which the macule with their surrounding zoccia
form polygonal areas bounded by thin crests or walls of mesopores
(see pl. 10, figs. 10, 11). Such an occurrence is not restricted to
this genus, since the same polygonal areas are formed on specimens

a a

\ /

\ df

Fic. 131.—DIANULITES PETROPOLITANA. @ AND 0, SIDE AND BASAL VIEWS OF THE VARIETY IN THE WESEN-
BERG LIMESTONE; ¢ AND d, TANGENTIAL SECTION, X20, AND WALL STRUCTURE OF SAME MUCH ENLARGED,

SHOWING IDENTITY WITH THE TYPICAL FORM OF THE SPECIES; € AND f, VERTICAL SECTION, X9 AND X20,
WITH FEWER DIAPHRAGMS THAN USUAL. WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

of Stellipora and Constellaria, but the present species is the only
Dianulites in which they have been observed. As shown in plate 10,
figure 11, the same specimen may present the characters of both the
species and the so-called variety. The latter is, therefore, placed in
synonymy, as is also the name Hexaporites, which, moreover, was
never described as a generic name.

On account of the complicated history and rather curious varia-
tion of Dianulites petropolitana, the species has been illustrated in
some detail. Comparison of figure 1380 with figure 132 shows essen-

92602°—Bull. 77—11——17

236 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

tially the same structure in the American form Monotrypa cumulata,
and its identity with D. petropolitana is further evidenced by direct
comparison of specimens of the two.

Dianulites petropolitana may be defined briefly as follows:
- Zoarium massive, usually hemispheric with a slightly concave,
epithecated base, and about 2.5 cm. wide, but ranging from this to
large expansions 10 or more cm. across. Some specimens are of irreg-
ular shape but almost always show their origin from the usual hemi-
spheric forms. Celluliferous side usually smooth, but sometimes
divided into polygonal, usually hexagonal, areas bounded by crest-
like elevations formed of mesopores. At the center of these areas is a
similarly elevated cluster of mesopores forming the macula. Zocecia
thin-walled, polygonal, averaging four in 2 mm. Mesopores few,

pag

Fig. 132.—DIANULITES PETROPOLITANA. ULRICH’S VIEWS OF MONOTRYPA (CHAETETES) CUMULATA, INTRO-
DUCED FOR COMPARISON. @ANDC, TANGENTIAL SECTION, X9, AND A SMALL PORTION, X35, SHOWING
WALL STRUCTURE; 0, VERTICAL SECTION, X9. LOWER PART OF THE TRENTON LIMESTONE, GOODHUE
County, MINNESOTA.

restricted usually to the macula and to the edges of the polygonal
areas noted above. Acanthopores absent. Diaphragms placed at
irregular intervals in the zoccial tubes but usually at distances vary-
ing between one and two tube diameters. In the mesopores three
diaphragms occur in a distance of their own diameter. Walls exhib-
iting the minute granules seen in the typical species of Dianulites.

In figure 1294 the usual structure seen in thin sections is illustrated,
although it is difficult to give in a drawing a correct impression of the
peculiar granular wall structure. In these figures it will be noted
that mesopores are almost entirely absent.

Figure 130 represents thin sections of a specimen with more abun-
dant mesopores, in fact, this specimen showed the hexagonal areas
of Dybowski’s variety hexaporites. Aside from the mesopores, the
structure is exactly the same as shown in the preceding figure.

Specimens from the Wesenberg limestone differ only in having
fewer diaphragms as shown in figure 131. In figure 132, Ulrich’s

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 237

illustrations of the Minnesota species Monotrypa cumulata are given
- for comparison.

Occurrence—An extremely abundant species in probably all the
formations ranging from the Glauconite limestone (B2) to the Wesen-
berg limestone (HZ). The collections of the United States National
Museum contain specimens from the Glauconite limestone (B2) at
Tswos, on the Wolchow River, Duboviki, Gornaja Scheldicha, and
Pawlovsk, government of St. Petersburg; from the Orthoceras lime-
stone (B3) at Reval, Malla, and Port Kunda, Esthonia, and Paw-
lovsk, government of St. Petersburg; from the Echinospherites lime-
stone (C1) at Luggenhusen, Katlino, 4 miles east of Reval, and
Duboviki; and from the Wesenberg limestone (EZ) at Wesenberg.
Dybowski mentions a number of other localities, such as Kuckers
and Jewe, which have afforded specimens. The American form was
found in the Lower Trenton limestone, Goodhue County, Minnesota,
and at Ottawa, Canada.

Plesiotypes.—Cat. Nos. 26906, 57339 to 57350, U.S.N.M.

Represented in British Museum by specimens from various locali-
ties in Russia and from the island of Oeland.

DIANULITES GRANDIS, new species.

Text fig. 133.

Zoarium massive, regularly hemispheric, consisting of numerous
superposed layers of zocecia. The type-specimen is 6 cm. in diam-
eter and about 3 cm. high. The base as usual in such forms is
slightly concave and is covered with a concentrically wrinkled
epitheca; upper surface celluliferous and smooth. The zoccia are
‘large, exceptionally thin-walled, polygonal, with distinct clusters of
larger size than the average at intervals of about 6 mm.; two to
three zocwecia in 2 mm., one of the average size being 0.8 mm. in
diameter, while those forming the maculze are frequently over a
millimeter wide. Mesopores and acanthopores absent. On the
best preserved portions of the surface exceptionally small granules
may be observed on the zoccial walls. These appear to better
advantage in tangential sections, although even here, on account
of the great tenuity of the zoccial walls, they seldom are as dis-
tinctly marked as I have shown them in figure 133 e. Vertical
sections show thin, slightly crenulated walls with three or more
diaphragms in a tube diameter in the mature zone. Figure 133 d
illustrates the occurrence of several superposed zocecial layers, each
with its short, immature zone and a longer mature portion with
numerous diaphragms.

The hemispheric zoarium, thin walls, and exceptionally large
zocecia are sufficient to distinguish this from all similarly growing

238 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

species. The minutely granulose wall structure determines the
generic position, although the granules are seldom clearly exhibited.
Dianulites petropolitana has a similar zoarium but its zocecia are a
third of a diameter less in size.

Se arian GERI

a i oa
x 7 % :
Tl fen ee ‘ pe : ge
g é
i

Fig. 133.—DIANULITES GRANDIS. @, THE TYPE-SPECIMEN, TWO-THIRDS NATURAL SIZE, IN SIDE VIEW; 8,
VIEW SHOWING SIMPLICITY OF STRUCTURE SEEN IN THE ORDINARY TANGENTIAL SECTION, X8; €, PORTION
OF THE SAME, X20, WITH THE GRANULES PLAINLY EXHIBITED ON THE WALLS OF A FEW ZOGCIA; d, TABU-
LATION IN VERTICAL SECTION, X8, CUTTING FOUR LAYERS OF ZOGCIA; €, SEVERAL TUBES OF A SINGIE
LAYER, X20, EXHIBITING THE TYPICAL DISTRIBUTION OF DIAPHRAGMS. LYCKHOLM LIMESTONE (F1),
PIERSAL, ESTHONIA.

Occurrence.—Apparently rare in the Lyckholm limestone (1) at

Piersal, Esthonia.
Holotype.—Cat. No. 57351, U.S.N.M.
British Museum, thin sections and portion of the type-specimen.

e
EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 239

DIANULITES COLLIFERA, new species.

Text fig. 134.

The internal structure of this species is quite similar to that of
Dianulites petropolitana. Externally there is no difficulty in sepa-
rating the low hemispheric zoarium of the present form with its
nodulated surface (fig. 134 a@ and 6) from the smooth, dome-shaped

a

Fig. 134.—DIANULITES COLLIFERA. @ AND b, SIDE AND FRONT VIEWS OF THE TYPE-SPECIMEN, NATURAL
SIZE; C, SURFACE, 9, WITH DISTINCT GRANULES ALONG THE WALLS; d, THE USUAL ASPECT PRESENTED
IN TANGENTIAL SECTIONS, X20; €, VERTICAL SECTION OF SEVERAL TUBES, X20; f, A ZO@CIUM, X35, IN A
TANGENTIAL SECTION WITH THE CHARACTERISTIC WALL STRUCTURE. LYCKHOLM LIMESTONE (F1),
KERTEL, ISLAND OF DAGO.

7

masses of the former. The zoccia of D. collifera are thin walled,
and show the characteristic granules of Dzanulites exceptionally
well, both at the surface and in thin sections. Five zoccia occur
in 3 mm.; mesopores usually few but sometimes numerous enough
to average one to a zowcium. ‘True acanthopores wanting. Tabule
at intervals varying from one and a half to two tube diameters apart.

&
240 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The nodulated surface of the zoarium and conspicuous granulated
zocecial walls are the most obvious characters which may be employed
in distinguishmg this species. The similarity in internal structure
to D. petropolitana has been mentioned, and it is possible that larger
collections will prove the present species to be more closely related
than now recognized.

Occurrence.—Apparently rare in the Lyckholm limestone (F1) at
Kertel, island of Dago.

Eble tne No. 57352, U.S.N.M.

British Museum, thin sections of the type-specimen.

Family BATOSTOMELLIDZ Ulrich.

In this family the amalgamate nature of the zoccial walls is most
marked, in fact so much so that adjoming walls usually appear
as completely fused together. Although the family is well repre-
sented in Ordovician strata, species with the most completely amal-
gamated walls, such as in Batostomella and Stenopora, are restricted
to later Paleozoic rocks. Of the genera discussed in this work,
Bythopora, LInoclemella, and Lioclema are typical Batostomellide.
Eichwald’s Orbipora is referred to the family on account of its fused
walls, while the new genus Hsthomopora is considered as a primitive
type of Stenopora. FEridotrypa, although probably best- placed in
the family, is a somewhat aberrant genus having relations with the
H. similis section of Homotrypa.

Genus BYTHOPORA Miller and Dyer.

Bythopora MituER and Dyer, Contr. to Pal., No. 2, 1878, p. 6—Mituer, North
Amer. Geol. and Pal., 1889, p. 295.—Utricu, Geol. Surv. Illinois, vol. 8,
1890, p. 376; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
263; Zittel’s Textbook of Paleontology, (Eng. ed.), 1896, p. 277.—Simpson,
Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897,
p. 551.—Nicxues and Basser, Bull. 173, U. 8. Geol. Surv., 1900, p. 32.—
GRABAU, Bull. Buffalo Soc. Nat. Sci., vol. 7, 1901, p. 166.—Basstrr, Bull.
292, U. S. Geol. Surv., 1906, p. 29.—Cumines, Thirty-second Ann. Rep.
Dep. Geol. Nat. Res. Indiana, 1907, p. 741.—Hernnie, Archiv fur Zool.,
vol. 4, No. 10, 1908, p. 44.

Species of Bythopora are uncommon in American Middle Ordo-
Vician strata and seem equally scarce in Russia, the following B. sub-
gracilis being the only one so far discovered in the rocks aa the lat-
ter country. The zoarium in Bythopora consists of slender branches
with small, oblique zocecial apertures narrowing above. The zoo-
cial interspaces are generally thick and are channeled. Mesopores
and diaphragms are few or wanting and acanthopores are never
numerous. At the surface the channeled interspaces and elongate
aperture are characteristic.

Genotype.—Bythopora fruticosa Miller and Dyer. Upper Ordo-
vician (Maysville) of the Ohio Valley.

BARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 241

BYTHOPORA SUBGRACILIS (Ulrich).

Text figs. 135, 136.

Homotrypella? subgracilis Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 230, pl. 26, figs. 10-16.

The author of this species referred it doubtfully to Homotrypella
because the preservation of the internal structure was such that the
cystiphragms were thought to have been destroyed. Better pre-

a d

Fic. 135.—BYTHOPORA SUBGRACILIS. @, AN ORDINARY FRAGMENT, NATURAL SIZE; 0, SURFACE OF SPECI-
MEN, X9; Cc, TANGENTIAL SECTION OF A POORLY PRESERVED FRAGMENT, X18; d, VERTICAL SECTION, X18.
RHINIDICTYA BED OF BLACK RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.)

served examples from the type locality have shown that cystiphragms

are entirely wanting and that generically the species differs in no

_ way from the other large forms of Bythopora. The identification of

this species in the Russian strata is based upon several well-pre-

served specimens, agreeing in
all respects with the typical "

Minn 1 Ch,

esota, examples. tra seb)
(OO)

)

TaN a)

The zoarium of Bythopora OG
subgracilis is of small, ramose, ih Nine
subcylindrical, smooth (Av ‘
Sree oi ALIS f Toney

branches 2 to 4 mm. in diam- i) a NUS Si
eter. The zocecial apertures. iy: PNOTAN
are oblique or long drawn IX CRN
LANA

Qo

out in young examples and
di ti ] d f Fig. 136.—BYTHOPORA SUBGRACILIS. @ AND 6, TANGEN-
more direct im Older torms, TIAL AND VERTICAL SECTIONS, X20, OF A WELL-

eight in 2mm. In the early PRESERVED RUSSIAN EXAMPLE. WASSALEM BEDS
stages acanthopores are few, (09 V*Nom* EstHonta.

but as the apertures become direct numerous small acanthopores are
developed. Mesopores are about as numerous as the zoecia, which
they often resemble so closely that it is difficult to distinguish them.
Diaphragms are entirely wanting, as shown in the vertical sections
figured herewith.

242 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The narrow, smooth zoccia, usually with long drawn-out zocecial
apertures separated by similarly shaped mesopore spaces and the
absence of diaphragms, will serve to distinguish this species from
associated small, ramose Trepostomata. The characters of speci-
mens from Minnesota are shown in figure 135, while the identity of
the Russian examples is apparent from the internal structure illus-
trated in figure 136.

- Occurrence.—Not uncommon in the Rhinidictya bed of the Black
River (Decorah) shales of Minnesota. Less common in the Was-
salem beds (D3) at Uxnorm, Esthonia.

Plesiotype.—Cat. No. 57314, U.S.N.M.

Specimens and thin sections from Uxnorm in the collections of
the British Museum.

Genus ERIDOTRYPA Ulrich.

Batostomella (part) UnRicH, Geol. Surv. Illinois, vol. 8, 1890, pp. 375, 432.

Fridotrypa Utricx, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p.
264.—NickLEs and BasstErR, Bull. 173, U. 8. Geol. Surv., 1900, p. 32.—
Basser, Bull. 292, U. S. Geol. Surv., 1906, p. 29.—Cuminas, Thirty-second
Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 745.—Hznnie, Archiv fur
Zool., vol. 4, No. 21, 1908, p. 36.

Zoarium ramose, branches slender; zocecia more or less oblique,
thick-walled, and intersected by diaphragms, which are most numer-
ous and most closely set in the earlier portion of the short, mature
region; mesopores sometimes numerous, sometimes few, with closely
set diaphragms; acanthopores small, few, or wanting.

Genotype.— Eridotrypa mutabilis Ulrich. Middle Ordovician (Black
River) of the Mississippi Valley.

All of the American Black River species of Eridotrypa are repre-
sented in the several formations of division D, and in the Wesenberg
limestone.

ERIDOTRYPA ZDILIS (Eichwald).

Plate 4, figs. 5, 5a; text figs. 137, 138.

Cladopora xdilis ErcHwaup, Bull. Soc. Nat. Moscou, No. 4, 1855, p. 457; Lethza
Rossica, vol. 1, 1860, p. 404, pl. 24, figs. 12, 13.

Monticulipora xdilis DyBowsx1, Die Cheetetiden Ostbaltischen Silur-Formation,
1877, p. 98, pl. 3, figs. 5, 5a.

Eridotrypa mutabilis Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 265, pl. 26, figs. 20-32.

The Wesenberg beds of the Russian Baltic provinces contain
abundant specimens of the bryozoan well figured by Hichwald as
Cladopora xdilis. The same species occurs less abundantly in the
different divisions of formation D. Upon comparison these speci-
mens are found to be identical with a very common, wide-spread
American species, Eridotrypa mutabilis Ulrich, occurring in the
Black River and lower Trenton strata. Dybowski has given good

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 243

although somewhat diagrammatic views of the internal structure of
Hichwald’s species (pl. 4, fig. 5), and these, in connection with the
original figures, are sufficient for purposes of identification. As usual
in this genus, and as indicated in the name applied to the American
form, the surface characters particularly are somewhat variable.
This variation is mainly dependent upon age. Thus, in Eichwald’s
figure (fig. 137), the two fragments are of young zoaria in which the
zocecia are elongate and separated by similarly elongated, shallow
mesopore spaces. The other extreme, that of old age, is shown in
Ulrich’s illustration (fig. 138 6). The internal characters are most
constant and will serve whenever doubt is raised.

Ulrich has given a detailed description, from which the following
notes are derived:

Zoarium of ramose branches 2 to 6 mm. in diameter, the younger
examples slender and nearly cylindrical, the old ones more or less

Fig. 137.—ERIDOTRYPA ee OF EICHWALD’S FIGURES OF CLADOPORA ZDILIS. @ AND C, TWO
FRAGMENTS OF THE NATURAL SIZE; 6 AND d, ENLARGEMENTS OF THE SAME SPECIMENS. WESENBERG
LIMESTONE (EF), WESENBERG, ESTHONIA.

irregular. Zocecial apertures variable, the changes due chiefly to age,

always oblique, the degree decreasing with age; walls thick, generally

ridge-shaped, and highest posteriorly, sloping gradually down into the
apertures. In young examples, also in old ones on which a new layer
of zocecial tubes was formed, the apertures may be exceedingly oblique
and drawn out anteriorly. With age they became gradually more
direct. The arrangement of the apertures is always more or less
irregular, some of the short rows having six, others seven, and occa-
sionally eight, in 2mm. Small macule, either pitted or irregularly
sculptured, commonly present in the older examples. In others the
macule are represented by clusters of zocecia which, though a little
larger than the average, are distinguished from them chiefly by the
ereater thickness of the interspaces. The mesopores too are most
variable, sometimes appearing to be wanting over large portions of
the surface and at other times twice as numerous as the zoccia.
As a rule, however, they are few, appearing at the surface as occa-

244 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

sional shallow depressions between the zoccial apertures. True
acanthopores probably wanting, but small knots at the angles of
junction may be noticed.

Eridotrypa xdilis may be distinguished from associated ramose
bryozoans by its slender, cylindrical, infrequently dividing, smooth
branches, with more or less oblique apertures and thick walls or inter-
apertural spaces. |

Occurrence.—Very abundant in the Wesenberg beds (EK) at Wesen-
berg (Cat. No. 44827, U.S.N.M.). Less common in the Jewe lime-

Fig. 138.—ERIDOTRYPA ZDILIS. COPIES OF ULRICH’S FIGURES OF ERIDOTRYPA MUTABILIS. @, SPECIMEN
OF AVERAGE SIZE; 0, SURFACE OF ANOTHER EXAMPLE, X18, EXHIBITING A MACULA AND NEIGHBORING
ZOGCIA; Cc, TANGENTIAL SECTIONS, X18, REPRESENTING THE MATURE CONDITION; d, A ZO@CIUM OF THE
SAME SECTION, X50; €, VERTICAL SECTION, X18, OF A MATURE EXAMPLE WITH AN INCRUSTING LAYER
OF ZOG@CIA GROWING IN THE OPPOSITE DIRECTION. LOWER PART OF TRENTON LIMESTONE, GOODHUE
County, MINNESOTA.

stone (D1), Baron Toll’s estate (Cat. No. 57316, U.S.N.M.); in the
Kegel limestone (D2), at Kegel (Cat. No. 57317, U.S.N.M.); and in
the Wassalem beds (D3), at Uxnorm, Esthonia (Cat. No. 57315,
U.S.N.M.). In America the species is abundant in Black River and
Trenton strata at localities too numerous to mention. The speci-
mens figured by Hichwald and Dybowski were derived from the
Wesenberg beds at Wesenberg, while Ulrich’s type-specimen came
from the lower Trenton shales at Cannon Falls, Minnesota.

British Museum, three specimens and one thin section from Rus-
sian localities.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 245
ERIDOTRYPA ZEDILIS MINOR (Ulrich).
Text fig. 139.

Eridotrypa mutabilis var. minor Uuricw, Geol. and Nat. Hist. Surv. Minnesota,
vol. 3, pt. 1, 1893, p. 266, pl. 26, figs. 20, 21, 29, 30.
This varietal name was proposed for specimens differing from the
more common form mainly in their internal structure. These differ-
ences, quoting from Ulrich, are as follows:
First, the central tubes are unusually large and their walls more wavy than in
typical mutabilis; second, the tubes altogether seem to have been developed more

regularly, and their width in the peripheral region somewhat less; and third, dia-
phragms are wanting throughout the greater part of the axial region. Under ordinary

MINOR. @,b, AND ¢, THREE AVERAGE FRAGMENTS; d, SURFACE OF A FRAGMENT, X9; €, TANGENTIAL
SECTION, X18; f, VERTICAL SECTION, X18. LOWER PART OF TRENTON LIMESTONE, NEAR CANNON FALLS,
MINNESOTA.

circumstances these differences would be considered as of specific value, but in this
instance, knowing the extreme variability of the species, I can not credit them with
more than subordinate importance.

Occurrence.—V ariety minor is known only from the lowest Trenton
at Cannon Falls, Minnesota, and from the Wesenberg limestone (i)
at Wesenberg (Cat. No. 57318, U.S.N.M.).

British Museum, represented by specimens from American locali-

ties.
ERIDOTRYPA EXIGUA Ulrich.

Text fig. 140.

Eridotrypa exigua Uuricn, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 266, pl. 26, figs. 17, 18.

Original description.—Zoarium small, branches very slender, several hundred frag-
ments varying in diameter from 0.6 to 1.0 mm.; bifurcations apparently remote. Some
of the fragments are pointed at the lower end, indicating a free condition of the zoa-
rium, or an articulation like that of Escharopora. The eastern form of the species is
usually a little stronger than the average of the Minnesota types, the specimens
seen from Vermont and New York being mostly 1.0 mm. or a little more in diameter.

246 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Considering the small size of the branches, the zocecia are large. Their apertures are
oblique, but not excessively so, subequal, and arranged in both longitudinal aad
diagonal series, the former with eight in 3 mm., predominating in the small speci-
mens, and the latter in the larger. At
the lower end of each aperture the wall
is usually raised into a spine-like promi-
nence. In vertical sections the greater
part of the branch is seen to consist of
comparatively large and nearly or quite
vertical tubes, intersected here and there
by a diaphragm. The peripheral region
is exceedingly short and abrupt.
Occurrence. — This neat little
. Species is very abundant in the
Fic. 140.—ERIDOTRYPA EXIGUA. 4, GROUP OF Nematopora bed of the Lower
FRAGMENTS, NATURAL SIZE; 6 AND C, TWO OF :
THEM, X9. NEMATOPORA BED OF THE LOWER Trenton at Cannon Falls, Minne-
TRENTON LIMESTONE, NEAR CANNON Fatis, gota; it also occurs in the lower
ee Rete The part of the Trenton limestone at
Trenton Falls, New York, and Chimney Point, Vermont. The spe-
cies is represented in the Russian collections by a number of exam-
ples from the Jewe limestone (D1), Baron Toll’s estate, near Jewe
(Cat. No. 57219, U.S.N.M.).
British Museum, one specimen from Jewe limestone, Baron Toll’s
estate.

Genus LIOCLEMA Ulrich.

Leioclema Uuricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, pp. 141, 154.—
MitteR, North Amer. Geol. and Pal., 1889, p. 310.—Utricu, Geol. Surv.
Illinois, vol. 8, 1890, pp. 376, 425.

Tioclema, NickitEs and BasstErR, Bull. 173, U. 8. Geol. Surv., 1900, p. 33.—
Utricn and BasstEerR, Smiths. Misc. Coll., vol. 47, 1904, p. 38.—BasstEr,
Bull. 292, U. 8S. Geol. Surv., 1906, p. 32.

This genus has its best representation in the Devonian, although
a fair number of species is known from both Silurian and Mississippian
deposits. Hitherto the oldest known species has been Lioclema
wilmingtonensis Ulrich, from the earliest Silurian (Richmond) forma-
tion of Iilmois. The following new species gives a greater antiquity
for the genus, although it occurs in the same faunal region as the
Richmond form.

The form of growth in Lioclema varies from the incrusting through
the explanate and solid massive to the ramose. ‘The batostomelloid
character of the fused walls is less evident in this genus, particularly
in the earlier forms, such as the one described below. The numerous
acanthopores inflecting the zocecia and the isolation of the sparsely
tabulated zocecia by closely tabulated, angular, thm-walled mesopores
are other characters which will aid in the recognition of the genus.

Genotype.—Callopora punciata Hall. Mississippian (Keokuk and
Warsaw) strata of the Mississippi Valley.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 247

LIOCLEMA VETUSTUM, new species.

Text fig. 141.

Zoarium consisting of small, irregular patches, less than 0.5 mm.
in thickness, growing upon foreign objects. The type-specimen,
from which the figured thin sections were prepared, is incrusting
an Orthoceras, while the example shown in figure 141 a, is growing
upon the cystid LEchinospherites. The surface is conspicuously
smooth and shows no distinctly marked clusters of larger zoccia
or mesopores. The zoccial apertures are quite small and somewhat
elongate, averaging 0.3 mm. in their longer diameter, with four to
five in 2 mm.; small acanthopores, in number about three to a

_J) Big J nay

Fig. 141.—LIocLEMA ORS, a, A ZOARIUM, NATURAL SIZE, INCRUSTING AN ECHINOSPHERITES; 3,
TANGENTIAL SECTION, X20, SHOWING THE USUAL ARRANGEMENT OF ZOGCIA AND ACANTHOPORES; C, POR-
TION OF THE SAME, X35, WITH THE SIMPLICITY OF WALL STRUCTURE MORE EVIDENT; d, VERTICAL SECTION,
X20, EXHIBITING TENUITY OF ZOARIUM. KUCKERS SHALE (C2), REVAL AND BARON TOLL’S ESTATE,
ESTHONIA.

zocecium, indent the cavity and cause the petaloid shape of the aper-

ture. Mesopores angular and numerous enough to isolate the zocecia;

walls of both kinds of cells thin.

Vertical sections are difficult to secure on account of the thin
zoarium, but all of the structure exhibited in several of these is
illustrated in figure 141 d. The absence of diaphragms in the
zocecia and their abundance in the numerous mesopores are the most
noteworthy features. The appearance in tangential sections is
practically the same as in views of the surface.

The delicate incrusting zoarium and the small, petaloid zocecia,
isolated by thin-walled, angular mesopores, are so different from other
Ordovician bryozoans that comparisons are unnecessary.

Occurrence—Apparently not uncommon in the Kuckers shale
(C 2), Baron Toll’s estate, near Jewe, and in the same rocks at Reval,
Esthonia.

Holotype.—Cat. No. 57320, U.S.N.M.

248 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

LIOCLEMA SPINEUM, new species.

Text fig. 142.

Zoarium of small, rounded, branching stems, 6 to 7 mm. in diame-
ter. Surface without monticules or conspicuous macule, but much
roughened by unusually large acanthopores. Zoccia polygonal,
direct, thin-walled, of average size, about 0.4 mm. in diameter, almost
always separated from each other by large, angular mesopores.
About three zowcia in 2mm. The macule are discernible, usually

Fig. 142.—LIOCLEMA SPINEUM. @, TANGENTIAL SECTION, X9, SHOWING RELATIONS OF ZOGCIA, MESOPORES,
AND ACANTHOPORES; 6, THE DETAILED STRUCTURE OF AN ACANTHOPORE, X40; C, PORTION OF A TANGEN-
TIAL SECTION, X20, WITH THE MESOPORES SHADED; d, VERTICAL SECTION, X20. ORTHOCERAS LIMESTONE

(B38), ISLAND OF ROGO, ESTHONIA. .
only in thin sections, by the presence of more numerous mesopores
and slightly larger zocecia. Mesopores thin-walled, often larger than
the zocecia but differing from them in having fewer sides. Moreover,
the mesopores are frequently closed by the outermost of the num-
erous diaphragms crossing their tubes. Acanthopores very large
and bluntly rounded, often equaling a zocecium in diameter.

The relative size and arrangement of the zoccia, mesopores, and
acanthopores are well shown in tangential sections. Here the zoccia
are seen to be more regularly polygonal than the mesopores and to
have slightly thicker walls. The irregularity in shape and frequent

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 249

large size of the mesopores is evident in figures 142 a-c. The acan-
thopore is so large that its minute structure is very clear. Sections
cutting across the acanthopore show a rounded structure of concen-
tric rings with a central clear space. In vertical sections the con-
centric rings are seen to be the cut edges of cones of tissue arranged
upon each other. Each of these cones has its apex truncated, and, as
a result, a tube passes through the midlength of the acanthopore.
In tangential section this tube is represented by the central clear
space. Diaphragms are rather frequent in the immature zone of the
zocecia but few in the mature region. The mesopores are rather
closely tabulated throughout. ;

The exceptionally large acanthopores will distinguish this from
all other ramose bryozoans. Lioclemella clava has a somewhat
similar zocecial structure, but has smaller and more numerous
acanthopores as well as a different growth habit.

Occurrence.—Not uncommon in the Orthoceras limestone (B3) on
the island of Rogo, near Baltischport (Cat. No. 57322, U.S.N.M.);
in the Echinospherites limestone (C1), 4 miles east of Reval (Cat.
No. 57323, U.S.N.M.); and in the Kuckers shale (C2), Baron Toll’s
estate, near Jewe (Cat. No. 57324, U.S.N.M.), Esthonia. Rare in
the Chasmops limestone, south of Bédahamn, island of Oeland.

Holotype.—Cat. No. 57322, U.S.N.M.

British Museum, thin sections of the type-specimen, and specimens
from other localities in Russia.

Genus LIOCLEMELLA Foerste.

Lioclemetla Forrsts, Geol. Surv. Ohio, vol. 7, 1895, p. 600 —NicKLEs and BASSLER
Bull. 173, U.S. Geol. Surv., 1900, p. 33.—Utricu and Basster, Smiths. Misc.
Coll., vol. 47, 1904, p. 389.—BasstxR, Bull. 292, U.S. Geol. Surv., 1906, p. 36.
Species of this genus may be readily recognized by their club-
shaped or sparsely divided branches pointed at the distal end for
articulation with an attached expanded base. In zoccial structure
the genus is so closely related to Lioclema that it is difficult to indicate
any distinguishing characters. Species with such a jointed zoarium
are not uncommon in the earliest Silurian (Richmond) strata of
North America, and continue, although less abundant, into the
Silurian. There is little doubt that the following new species is an
unequivocal member of the genus.
Genotype.—Callopora ohioensis Foerste. Silurian (Clinton) of the
Ohio Valley.

LIOCLEMELLA CLAVA, new species.
Text fig. 143.

Zoarium of cylindrical, slightly curved, unbranched club-shaped

stems, 6 mm. in diameter and about 60 mm. long, pointed at the

lower portion for articulation with an attached, expanded base, and

250 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.
®

rounded at the distal end where possibly a second articulation
occurred. Surface free from monticules but hirsute because of the
great number of large acanthopores. Macule composed of zocecia
larger than usual are present but quite inconspicuous. About four
zocecia in 2 mm. Zoccial aperture subangular to rounded, the
shape depending upon the number of mesopores which vary in
number, but are sometimes so abundant as to isolate the zocecia.

Fic. 148.—LIocLEMELLA CLAVA. @, THE TYPE-SPECIMEN, NATURAL SIZE; 0, TANGENTIAL SECTION, X20,
EXHIBITING THE NUMEROUS LARGE ACANTHOPORES; C, VERTICAL SECTION, X8, ILLUSTRATING THE TABU-
LATION; d, PORTION OF THE SAME, X20. KEGEL BEDS (D2), HABBINEM, ESTHONIA.

Acanthopores both large and numerous, appearing at the surface as
blunt, perforated spines occupying the junction angles of zoccia and
mesopores.

The most striking feature of tangential sections is the number
and size of the acanthopores. These are frequently so large that —
the place of an ordinary mesopore is occupied by one, and four or five
may be noted about a single zocecium. The material composing an
acanthopore is of a lighter color and more granular nature than the
solid, dark tissue making up the rest of the zoartum. The walls of

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 251

adjacent zocecia and mesopores are obscured by amalgamation, which,
in thin sections, gives them the aspect of a solid, indivisible structure.
In vertical sections the diaphragms of the zocecia are noted to average
twice their own diameter apart in the immature zone, and to be
sometimes entirely wanting in the mature region. In the mesopores,
diaphragms are numerous and are usually about their own diameter
apart.

The club-shaped zoarium pointed at the base, large zoccia, and
numerous as well as large acanthopores studding the surface, are
specific characters which will not allow the present form to be con-
founded with any associated bryozoan. Lioclema spineum, from the
Orthoceras limestone, has a somewhat similar zoccial structure, but
here the zoarium is regularly ramose, the zocecia are larger, and the
acanthopores are much stronger.

Occurrence.—-Apparently rare in the Jewe limestone (D1), Baron
Toll’s estate (Cat. No. 57327, U.S.N.M.); in the Kegel beds (D2) at
Habbinem (Cat. No. 57325 U.S.N.M.); and in the Wassalem beds (D3)
at Uxnorm (Cat. No. 57326 U.S.N.M.), Esthonia.

Holotype.—Cat. No. 57325, U.S.N.M.

British Museum, thin section of specimen from the Jewe limestone,
Baron Toll’s estate.

Genus ORBIPORA Eichwald,

Orbitulites EicHwaup, Zool. Spec., vol. 1, 1829, p.179.—M1nnE-Epwarps, Hist.
Nat. des Corall., vol. 3, 1860, p. 271 (name preoccupied).

Orbipora EicHWALD, Bull. Soc. Nat. Moscou, vol. 29, 1856, p. 92; Lethzea Rossica,
vol. 1, 1860, p. 484.—DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-—
Form., 1877, p. 57.—NicHoitson, Genus Monticulipora, 1881, p. 24.—WaAaAGEN
and WENTZEL, Pal. Indica, ser. 13, 1886, pp. 874, 876.—NicKLEs and
Bass eR, Bull. 173, U. 8. Geol. Surv., 1900, p. 333.

This generic name has failed of recognition in the more recent
work on Paleozoic Bryozoa, and I would not have thought it advisable
to resurrect it had not the genotype, Orbipora distincta, proved to belong
to an apparently unoccupied structural division. A detailed descrip-
tion of both the genus and type species was given by Dybowski in 1877,
but neither his work nor that of his predecessors can be considered of
much value for present day purposes. Hach writer’s definition of
the genus has proved so different that now the only method of
determining the real generic characters is by a reinvestigation of the
types or of authentic specimens of the genotype. Dybowski had
access to such specimens, but, although his description and figures in
connection with those previously published by Eichwald were suf-
ficient to identify the species with some certainty, they gave little
information regarding the generic characters. His ideas concerning
the genus were such that he referred here two new ramose species, O.
arborescens and O. panderi, the former belonging to a genus still unde-,

92602°—Bull, 77—11 18

252 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

termined and the latter an unequivocal Hemiphragma. Nicholson,
in remarking upon the genus in his volume ‘The Genus Monticulipora,”’
opposes the resurrection of the name.

Through the kindness of Dr. Mikhailowski, of the University of
Dorpat, I have had the opportunity of examining specimens of
Orbipora distincta studied by Dybowski, who, in turn, as stated before,
had access to Hichwald’s types. The Dybowski.examples are of a
well-marked discoid bryozoan easily recognized with sufficient
illustrations, and agreeing with a species which I had previously
identified from several horizons as a form belonging to a new genus
of the Batostomellide. Based upon the internal structure, which is
well marked in the numerous thin sections studied, this family
reference is made with some confidence, although a few features,
such as the apparent absence of macule, cause final placement of
the genus to be still a matter of doubt.

A second species, with the same internal characters, but differing
in having a more massive zoariam and smaller zocecia, is not uncom-
mon in the Orthoceras limestone (B3) at Reval and vicinity, while
two well marked forms occur in the lower Asaphus limestone of the
island of Oeland.

Based upon these four species, Orbipora may be defined as follows:

Zoarium typically discoid, slightly convex above, flat and with a
wrinkled epitheca on the underside, or of small, rounded or more or
less elongated masses; composed of polygonal, frequently hexagonal,
zocecial tubes in close contact; macule apparently absent, if present
at all, quite inconspicuous; mesopores wanting, diaphragms extremely
few. Acanthopores of considerable size and number, giving a spinous
aspect to the surface and frequently indenting the zoccial walls.
Thin sections show that the structure of the walls and acanthopores is
consistent with that prevailing in the Batostomellide. The walls of
adjoining zocecia are fused together and appear as one amalgamated
structure instead of two distinct bands separated by a dark divisional
line as in other families. The acanthopores likewise have the clear
central structure so well marked in Lioclema and Stenopora. An
exceptionally well preserved specimen from the Chasmops limestone
on the island of Oeland shows that the acanthopore has a single row
of small pores or granules encircling the inner clear structure. The
nature of these pores, as indeed of the acanthopore itself, is unknown,
but these different structures certainly had some function.

Aside from its batostomelloid minute structure, the principal
generic features of Orbipora are its massive growth, absence of meso-
pores, few diaphragms, and ill-developed macule. This generic type
is not yet known in American strata.

- Genotype-—Orbipora distincta Kichwald. Middle Ordovician of
Russia and Sweden.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 253

ORBIPORA DISTINCTA (Eichwald).
Plate 3, figs. 10-10b; text figs. 144-147.

Orbitulites distinctus KicHwa.p, Zool. spec., vol. 1, 1829, p. 180.

Favosites hemisphxricus Kutorea, Beitrag zur Pal. Dorpats, 1835, p. 40, pl. 8,
figs. 5 a-c (not pl. 9, fig. 3).

Orbipora distincta Ercuwa.p, Bull. Soc. Nat. Moscou, No. 1, 1856, p. 93; Lethza
Rossica, vol. 1, sect. 1, 1860, p. 484, pl. 28, figs. 6, 7 a-c.—DyBowsk1, Die
Cheetetiden der Silur-Formation, 1877, p. 60, pl. 2, figs. 10, 10a, 10b.

Chaetetes hemisphxricus EicHwaup, Lethzea Rossica, vol. 1, sect. 1, 1860, p. 476,
pl. 28, fig. 5.

The general characters of this species have been mentioned in the
discussion of the genus, but these, as well as the more specific points,
are given in the following diagnosis.

Zoarium consisting of a flattened,
discoidal mass, sometimes as much as
40 mm. wide and 7 mm. in its greatest
height, flat or slightly concave and
covered with a wrinkled epitheca on
its lower side, slightly convex on the
upper or celluliferous surface. Macule Fc. 144—Orprora pismvcra. a anp 5,

. ° ° ° BASAL AND CELLULIFEROUS SIDES OF A
eiumeriabsent or dimer: so little from) \ Senne coanew WATowAt a7e oEecEtiD
surrounding areas that they are indis- 8 ¥ E1cuwatp as Cuanreres HEMISPHER-

. . : ° ICUS; C, SIDE VIEW OF THE SAME SPECIMEN;
mciishable: + Ther suriace is withoub! \ 99 “crreneenous suaeice uunkneED.
monticules or elevations of any sort, but “Catcame A OrrsoceramirEs,” Put-
: KOWA, GOVERNMENT OF ST. PETERSBURG.
is roughened by numerous sharp acan (pape EcHWALD.)
thopores. Zocecial tubes large, polyg-
onal, usually hexagonal, varying from 0.8 mm. to 1.0 mm. in diameter.
Mesopores absent entirely. Acanthopores numerous, as many as 16

surrounding a single zocecium.

Fic. 145.—ORBIPORA DISTINCTA. @ AND b, TOP AND SIDE VIEWS, NATURAL SIZE, OF ONE OF EICHWALD’S
TYPE-SPECIMENS OF ORBIPORA DISTINCTA; C, CELLULIFEROUS FACE ENLARGED; d, WORN PORTION OF
ZOARIAL BASE ENLARGED; €, VERTICAL SECTION; /, g, AND h, VIEWS OF A LARGER EXAMPLE REFERRED
TO THE SPECIES; 7, SIDE VIEW OF ZOGCIAL TUBES, “CALCAIRE A ORTHOCERATITES,”’ PULKOWA AND
WESENBERG. (AFTER EICHWALD.)

The internal characters of a well preserved specimen are shown in
figures 146 and 147. In tangential section fhe numerous large acan-
thopores are particularly noticeable. Here also the rather large

254 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

central opening or lumen of the acanthopores and the wall structure
of adjoining zoeecia are likewise well marked. This structure of the

Fig. 146.—ORBIPORA DISTINCTA. @, TANGENTIAL SECTION, X2), ILLUSTRATING THE USUAL STRUCTURES
NOTED; b, VERTICAL SECTION, X8, THROUGH A PORTION OF A ZOARIUM; C, SMALL PORTION OF THE SAME
SECTION, X20, SHOWING STRUCTURE OF WALLS AND ACANTHOPORES. JEWE LIMESTONE (D1), BARON
TOLL’S ESTATE, ESTHONIA.

acanthopores and of the zocecial walls is essentially the same as in

other Batostomellide, although the uniform diameter of the zocecia

and absence of macu-
lz are conspicuous
points of difference.

The same characters,

in addition to the ab-

sence of diaphragms,
are also well shown in
vertical sections.

The discoid zoarium,
exceptionally large

OF ie zoecia, Numerous

Fic. 147.—ORBIPORA DISTINCTA. @, TANGENTIAL SECTION, X20, IN

WHICH THE STRUCTURE IS WELL PRESERVED; 6, A PORTION OF A larg € acanthopores,

ZOGCIAL WALL, X35, EXHIBITING THE DETAILED STRUCTURE OF THE QN d the absence of
ACANTHOPORES. THE LARGE CENTRAL LUMEN AND THE GRANULES C

OR TUBULES OF THE ACANTHOPORE WALL ARE CLEARLY SHOWN. macu | 2 an d d 1a-

CHASMOPS LIMESTONE, NEAR BODAHAMN, ISLAND OF OELAND. phragms, are charac-

ters which will cause the present species to be recognized without

difficulty.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 255

Occurrence.—Eichwald cites the species from the ‘‘calcaire &
Orthoceratite,” at Pulkowa, Popowa, and Wesenberg. In the col-
lections before me it is present in the Echinospherites limestone (C1)
at Reval (Cat. No. 57329, U.S.N.M.); in the Kuckers shale (C2)
at Erras (Cat. No. 57330, U.S.N.M.); the Jewe limestone (D1),
Baron Toll’s estate (Cat. No. 57328, U.S.N.M.), Esthonia; and the
Chasmops limestone, south of Bédahamn, Oeland, Baltic Sea.

Plesiotype-—Cat. No. 57328, U.S.N.M.

British Museum, specimens from localities in Esthonia and from the

island of Oeland.

ORBIPORA SOLIDA, new species.

Text fig. 148.

Zoarium of dome-shaped, hemispheric or elongated solid masses
usually several centimeters in diameter and of corresponding height.
The type-specimen, which is one of the largest examples seen, is an
elongate oval mass about 40 mm. in diameter and 75 mm. in length.
Surface smooth, macule as in the type-species being apparently
absent. Zocecia direct, polygonal and of equal size when fully
matured. Occasionally a young zowcium giving the appearance of a
mesopore is present, but true mesopores are wanting. ‘Three to four
zocecia occur in 2mm. Acanthopores numerous and conspicuous at
the junction angles of the zocecia.

The internal structure is essentially the same as in Orbipora
distincta save that a few scattered diaphragms are occasionally
developed. The acanthopores, while not as numerous as in 0.
distincta, are larger and have very distinct central openings.

The more massive.zoarium, less abundant acanthopores, and par-
ticularly the smaller zoccia of the present species will readily dis-
tinguish it from the related form, O. distincta.

Occurrenee.—Not uncommon in the Orthoceras limestore (B3)
island of Rogo, and at Reval and vicinity.

Holotype.—Cat. No. 57331, U.S.N.M.

British Museum, fragment and thin sections of the type-specimen,
and specimens from Reval, Esthonia.

ORBIPORA ACANTHOPHORA, new species.
Text fig. 149.

Zoarium a rounded mass about a centimeter in diameter, with a
small, flat basal portion covered with a wrinkled epitheca. Surface
without monticules or macule, but hirsute on account of numerous
large acanthopores arising from the cell walls. Zoccial apertures
irregularly polygonal and much indented by the acanthopores; three
to four zocecia in 2 mm. Mesopores wanting; four to. six acantho-
pores surround an aperture.

>

256 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In thin sections the amalgamated cell walls and the very large
acanthopores composed of a clear, almost structureless tissue are the
most noteworthy features of the more minute details. Wherever an
acanthopore occurs the walls are greatly thickened, but they are quite
thin in the intervening spaces. This alternate thickening and thin-

Fig. 148.—ORBIPORA SOLIDA. @, SIDE VIEW, NATURAL SIZE, OF THE SOLID, MASSIVE TYPE-SPECIMEN; 0,
TANGENTIAL SECTION, X20, SHOWING ZOGCIAL STRUCTURE; €, VERTICAL SECTION, X8, ILLUSTRATING
THE USUAL TABULATION; d, ANOTHER VERTICAL SECTION, X20, WITH DIAPHRAGMS MORE REGULARLY
PLACED IN THE MATURE ZONE. ORTHOCERAS LIMESTONE (B3), REVAL, ESTHONIA.

ning produces a very irregular aperture with the acanthopore some-
times projecting some distance into the cell cavity. Vertical sections
show an occasional diaphragm, although most of the tubes are with-
out them. The minute structure of the walls and acanthopores is
exactly the same as in Orbipora distincta.

_ EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 257

This species is most closely related to Orbipora solida, agreeing with
it in all characters save the larger size and fewer number of its
acanthopores and its much smaller zoarium. A glance at figures 148
and 149 will indicate that in spite of their similar characters, the
tangential section of each is quite distinct. The associated Orbipora

a

Fic. 149.—ORBIPORA ACANTHOPHORA. @, THE TYPE-SPECIMEN, NATURAL SIZE; 0, TANGENTIAL SECTION,
X20, ILLUSTRATING THE IRREGULAR ZOG@:CIA AND NUMEROUS LARGE ACANTHOPORES; C, SEVERAL ZOG@CIA
OF THE SAME SECTION, X20, SHADED TO BRING OUT THE CLEAR TISSUE OF THE ACANTHOPORES AND THE
AMALGAMATED WALL STRUCTURE MORE PLAINLY; d, VERTICAL SECTION, X20, WITH STRUCTURE OF WALLS
AND ACANTHOPORES. LOWER ASAPHUS LIMESTONE, HALLUDDEN, ISLAND OF OELAND.

indenta has much smaller zocecia, thinner walls, and smaller acantho-
pores projecting far into the zocecial cavity.

Occurrence.—Rare in the lower Asaphus limestone at Halludden,
island of Oeland, Baltic Sea.

The type-specimen and figured thin sections are in the collections
of the British Museum.

ORBIPORA INDENTA, new species.
Text fig. 150.

On account of the deep indentation of the zoccial cavity by nu-
merous small acanthopores, a zoarium of this species often gives the
impression of a septate coral like Tetradwum. Thin sections, how-
ever, show that the minute structure is precisely as in the other
species here referred to Orbipora.

The zoarium of the type-specimen is a small, elongate, dome-shaped
mass, 14 mm. in height and 9 mm. wide, with the usual epithecated
flattened base. The surface is smooth and without perceptible

258 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

macule; the apertures are irregularly polygonal, five in 2 mm., with
thin walls; acanthopores small, four to eight or more surrounding a
zocecium, often occurring at the end of a fold of the wall extending
into the zocecial cavity. The arrangement of the diaphragms, struc-
ture of the walls and acanthopores, and other features brought out
in sections are shown in the accompanying figures and need not be
described. |

Although this is an undoubted, indeed, very typical species of the

genus, its zocecial structure has considerable resemblance to such

forms as Stigmatella septatum and S. foordw described on previous

a

{

Thaeenieeanneemeom rrr dhe rere

bas ‘4 ae

Be

eae
Kato

can
be)

Fig. 150.—ORBIPORA INDENTA. @, THE TYPE ZOARIUM, NATURAL SIZE; 6, TANGENTIAL SECTION, X20,
EXHIBITING THE NUMEROUS SMALL ACANTHOPORES INDENTING THE ZOGCIAL CAVITY; C, PORTION OF THE
SAME SECTION, X35, WITH THE WALL AND ACANTHOPORE STRUCTURE MORE CLEARLY SHOWN; d, VER-
TICAL SECTION, X20. LOWER ASAPHUS LIMESTONE, HALLUDDEN, ISLAND OF OELAND.

pages. Both of the latter have numerous mesopores so that this
feature alone will separate them. Compared with other species of
Orbipora, O. indenta is found to have smaller zocecia, thinner walls,
and more delicate acanthopores. The occurrence of the acanthopores
at the end of the infolded wali, giving the indented effect, is likewise
quite characteristic.

Occurrence.—Rare in the lower Asaphus limestone at Halludden,
island of Oeland, Baltic Sea, where it is associated with Orbipora
acanthophora.

The type-specimen and figured thin sections are in the collections
of the British Museum.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 259

ESTHONIOPORA, new genus.

The value of the minute wall structure as a reliable character in
classification is well exemplified in the group of species for which this
new hame is proposed. At first the two species now assigned to
Esthoniopora were regarded as somewhat aberrant forms of Hemi-
phragma, but more detailed investigation of the walls showed that
those of adjacent zocecia were fused together as in the Amalgamata
and were not separated by the distinct dark line characteristic of the
Integrata. Further study has convinced me that Hsthoniopora is a
member of the Batostomellide and not far removed from the late
Paleozoic genus Stenopora. Indeed, it is possible that the genus is the
simplest expression of the stenoporoid typeof structure. Thearrange-
ment of the diaphragms in EL. communis is highly suggestive of
Stenopora, although the beaded walls and the acanthopores of the
latter genus are wanting.

Esthoniopora may be defined as follows:

Zoarium massive, hemispheric, with a flat, concentrically wrinkled
base; composed of thin-walled, polygonal zocecia in close contact;
walls of great simplicity but clearly amalgamated; acanthopores and
mesopores absent; zocecial tubes with semidiaphragms which, in the
type species, are frequently placed opposite each other, and in a second
species, are large and curved enough to resemble a cystiphragm.

Genotype.—Esthoniopora communis, new species. Middle Ordo-
vician of Russia and Sweden.

The diagnostic features of Hsthoniopora are the massive zoarium,
polygonal zocecia with amalgamated walls and semidiaphragms, and
the absence of acanthopores and mesopores. All other genera of the
Batostomellide except Stenopora differ so obviously that comparisons
are hardly necessary. The relations between Stenopora and Hsthonio-
pora have been discussed above. The most difficulty will be experi-
enced in separating the species of this new genus from the simple
massive types of Hemiphragma, and thin sections are necessary to
show their distinct wall structure.

In this connection it may be mentioned that both of the species of
Esthoniopora agree in having their zocecial tubes filled with coarsely
crystalline calcite, which reflects and refracts the light so much that
vertical fractures often present an iridescent effect. This character,
if it may be so called, is not limited to the present genus, for all of
the species of Calloporina and Anaphragma show the same structure,
while other genera show no trace of it. Iam thus led to believe that,
although this is a purely physical character, it has an organic basis and
is thus of value in the discrimination of certain genera and species.

According to present knowledge, species of Esthoniopora are un-
known in American strata, and in Europe are confined to the Middle
Ordovician rocks of Esthonia and the neighboring Baltic Provinces.

260 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

ESTHONIOPORA COMMUNIS, new species.
Text figs. 151-155.

Zoarium of regular dome-shaped or hemispheric masses, with a flat,
concentrically wrinkled base; growth beginning upon some foreign
object, which, in the mature stages, is overgrown or is lost and
usually indicated only by the cicatrix of attachment. A well devel-
oped zoarium is 30 mm. in its basal diameter and 20 mm. in height,
but all sizes from this or even larger, down to masses less than 10 mm.
wide, arefound. The usual form of zoarium is shown in figure 152 4, 6,
but a less usual occurrence is illustrated in figure 155. Here the
zocecia of one portion of a normally growing example have continued
growth and have given rise to another normal but attached form.

Fig. 151—ESTHONIOPORA COMMUNIS. @ AND b, TWO VERTICAL SECTIONS, X20, SHOWING AN IRREGULAR
ARRANGEMENT OF THE SEMIDIAPHRAGMS. JCUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

Surface smooth, macule 4 to 5 mm. apart, inconspicuous to the un-
aided eye, and distinguished under a hand lens or in sections by
clusters of zocecia larger than the ordinary. Zocecia thin-walled,
polygonal, usually hexagonal, with three and one-half to four in the
space of 2 mm., measuring from the center of a macula. An ordi-
nary intermacular zocecium is 0.5 mm. in diameter. Mesopores and
acanthopores wanting. The bases of some zoaria are covered with
small, mesopore-like cells sometimes noticed in other massive
bryozoans.

Tangential sections show exceedingly simple zocecia with the thin
walls of those adjacent to each other amalgamated. No trace of
acanthopores or mesopores is visible, although small, mesopore-like
spaces representing young cells are sometimes present. In vertical
sections the presence of semidiaphragms at distances averaging a tube
diameter apart is the most important character to be noted. Fre-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 261

quently these semidiaphragms are seen to be placed directly opposite
each other in the same tube. In such a case, the structure is exactly
the same as the centrally perforated diaphragm of Stenopora. At
other times the partition extends only partially around the circum-
ference of the cell and appears in sections as a single projecting semi-
diaphragm.

The typical form of the species is illustrated in figure 152. The

regular hemispheric, solid zoarium is made up of a number of distinct

a
é

. ¥ 0)

Fic. 152.—ESTHONIOPORA COMMUNIS. 4d, SIDE VIEW OF AN AVERAGE SPECIMEN, NATURAL SIZE; 0, BASAL
VIEW OF SAME SHOWING EPITHECA AND CICATRIX OF ATTACHMENT; C, TANGENTIAL SECTION, X20, OF
AVERAGE ZOGCIA ; d, SEVERAL ZOGCIA OF THE SAME SECTION, X35, ILLUSTRATING SIMPLE, AMALGAMATED
WALL STRUCTURE; €, VERTICAL SECTION, X8, THROUGH TWO ZOARIAL LAYERS; /, PORTION OF THE SAME
SECTION, X20. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

zoarial layers, two of which are shown in the vertical section, figure
152 e. As usual in such zoaria, the tubes of these individual layers
are placed so nearly on top of each other that they form practically
one and the same tube throughout the colony.

In figure 154 the zoarium consists of a single layer in which the
semidiaphragms are placed opposite each other with considerable
regularity. Whenever tabule of this sort are cut by the tangential

262 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

section, they are seen to extend completely around the cavity, or
nearly so, as shown in figure 154 a.

Fic. 153—ESTHONIOPORA COMMUNIS. a, TANGENTIAL SECTION, X20, SHOWING NORMAL ZOGCIA IN THE
UPPER HALF, AND THE SMALL, THICK-WALLED, MESOPORELIKE CELLS IN THE LOWER PORTION; 0, VER-
TICAL SECTION OF THE SAME SPECIMEN, X20, WITH THE FREE ENDS OF THE DIAPHRAGMS BENT DOWNWARD;
C, A ZO@CIAL TUBE OF THE SAME SECTION, X20, SHOWING FURTHER MODIFICATION OF THE DIAPHRAGMS;
d, VERTICAL SECTION, X20, PASSING THROUGH A TRUE ZO@CIAL TUBE AND THROUGH TWO OF THE SMALLER
CELL OPENINGS OF THE BASE. GLAUCONITE LIMESTONE (B2), REVAL, ESTHONIA.

Fic. 154.—ESTHONIOPORA COMMUNIS. @, TANGENTIAL SECTION, X20, CUTTING THE SEMIDIAPHRAGMS IN
SOME OF THE TUBES; b, VERTICAL SECTION, X6, THROUGH A SINGLE ZOARIAL LAYER; C, A PORTION OF
THE SAME, X20. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

The peculiar form of growth mentioned in the specific diagnosis
above is shown in figure 155, while further interesting internal struc-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 263

ture is brought out in figures 151 and 153. The latter thin sections
were prepared from an example showing the base overgrown with
small cells. The tangential section (fig. 153 a) passes through this
layer of small cells and through the adjoining normal zoccia. The
forms differ from the latter simply in their small size and greater thick-
ness of walls. In vertical sections, however, they show more resem-
blance to mesopores in being closely tabulated. This is illustrated
in figure 153d. Figures 153 6 and c show an occurrence of the
diapbragm in which the free ends are either sharply bent downward
or have strings of tissue dependent from them. That the latter is
sometimes the case is evidenced in figure 153 c, where five such pro-
jections are noted on the lowest diaphragm.

In growth Esthoniopora communis is exactly like Dianulites petro-
politana, and the size, shape, and general aspect of their zocecia in
surface views are identical. After comparing
the figures of their totally different internal
structure one is impressed by the necessity
either of thin sections or of other means to ex-
amine the microscopic characters of fossil Tre-
postomata. With regard to all other Trepos-
tomata the incomplete diaphragms and amalga-
mated walls of the present form are the best
distinguishing characters. Comparisons with
Esthoniopora curvata are included under its de-
scription.

Occurrence.—A common fossil in the Glauco- "6. 155—EstuontoPora
nite limestone (B2) at Reval and at Oberchowow, tea ss Seen ate
on the river Wolchow; in the Orthoceras lime- a Rie age Ae en
stone (B3) at Port Kunda; in the Echinospher- ; Pi
ites limestone (C1) at Reval and 4 miles east of Reval, at Katlino, and
at Luggenhusen; in the Kuckers shale (C2), Baron Toll’s estate, near
Jewe, and at Erras; in the Jewe limestone (D1), Baron Toll’s estate.

Cotypes.—Cat. Nos. 57357 to 57365, U.S.N.M.

British Museum, specimens and thin sections from various locali-
ties in Esthonia.

“ESTHONIOPORA CURVATA, new species.
Text fig. 156.

In thin sections this species, with its long, slightly curved, cysti-
phragmlike, incomplete diaphragms, seems clearly distinct from the
preceding H. communis, although externally the two are practically
identical. A slight increase in the average size of both the macular
and intermacular cells is apparent upon close measurement, but this
aids little in the discrimination of the two species. However, ver-
tical fractures showing the different style of tabulation will distin-
guish EH. curvata at once. The fact that the incomplete diaphragm

264 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Fic. 156.—ESTHONIOPORA CURVATA, @ AND Bb, SIDE AND BASAL VIEWS OF A NORMAL EXAMPLE, NATURAL
SIZE; C, TANGENTIAL SECTION, X20, SHOWING THE SMALL OPENING LEFT BY THE INCOMPLETE DIAPHRAGM,
d, VERTICAL SECTION, X8, THROUGH PORTIONS OF TWO LAYERS, ILLUSTRATING THE CYSTIPHRAGMLIKE
INCOMPLETE DIAPHRAGM; €, ANOTHER VERTICAL SECTION, X20. ECHINOSPHERITES LIMESTONE (Ci),
DUBOVIKI, GOVERNMENT OF ST. PETERSBURG.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 265

extends almost across the cell cavity is apparent in tangential sec-
tions from the small opening left on one side. From the small size
of this curved portion it is also evident that the diaphragms extend
almost entirely around the zoccial cavity.

Occurrence.—Not uncommon in the Echinospherites limestone (C1)
at Reval and 4 miles east of Reval, in Esthonia, and at Katlino and
Duboviki in the government of St. Petersburg; in the Kuckers shale
(C2), Baron Toll’s estate, near Jewe. The species also occurs in the
Chasmops limestone on the island of Oeland, south of Bédahamn.
(Cat. Nos. 57366 to 57370).

British Museum, specimens from the island of Oeland.

Division INTEGRATA Ulrich and Bassler.
Family AMPLEXOPORID Ulrich.

The simplest types of the Integrata are included in this family,
_ which, because of this simplicity as well as the practical absence of
mesopores, shows the duplex character of the walls most distinctly.
In the Halloporide and Trematoporide mesopores are almost inva-
riably present, and the black divisional le is then only apparent
where the zoccial walls are in contact.

The Amplexoporide include forms of a ramose, massive, or bifoliate
growth. The zocecial tubes are simple, polygonal, with a distinct
divisional line. Mesopores are practically wanting, a few abortive
cells in the macule being their only representatives. Acanthopores
are generally abundant, although sometimes wanting.

The type genus of the family, Amplexopora, has no known repre-
sentation in the Ordovician of Russia or in the Black River deposits
of America. It is abundantly represented in the upper Trenton and
Cincinnatian formations of the Mississippi Valley. Monotrypella like-
wise occurs only in the formations containing faunas of supposed
South Atlantic origin. Rhombotrypa is found only in the earliest
Silurian deposits, where its several species are highly diagnostic fossils.
IT am convinced that further search will show this genus to be repre-
sented in the upper Lyckholm and Borkholm, where species asso-
ciated with it in America are known. ;

The discovery of a typical species of Petalotrypa in the Middle
Ordovician rocks of Russia increases the geologic range of the genus.
Hitherto it has been considered typical of the upper part of the
Silurian and of the Devonian.

Genus PETALOTRYPA Ulrich.

Petalotrypa Uxricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 377, 453.—Smeson,
Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897,

p- 582.—NickeEs and Bassxer, Bull. 173, U.S. Geol. Surv., 1900, p. 30.
Amplexoporide in which the zoarium forms delicate, bifoliate,
thin branches or fronds. The zoccial structure is essentially as in
other genera of the family; that is, the walls of adjoining cells are

266 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

distinctly marked off from each other by a black divisional line.
This dark line is sometimes broken or traversed by areas of the same
light-colored tissue making up the wall itself.

Genotype.—Petalotrypa compressa Ulrich. Middle Devonian of
Ihnois and Iowa.

PETALOTRYPA FOLIUM, new species.

Text fig. 157.

Zoarium a delicate, bifoliate expansion about 4 cm. in both height
and width and not exceeding a millimeter in thickness. Surface
smooth, with clusters of cell apertures, appreciably larger than the
average, at intervals of about 3.5 mm. Zoecial tubes regularly
polygonal, opening directly at the surface, seven in 2mm. Walls of
the zocecia thin and without acanthopores; mesopores either wanting
entirely or present only in the macule.

Fic. 157.—PETALOTRYPA FOLIUM. @, SURFACE OF THE TYPE-SPECIMEN, X9, SHOWING A MACULA IN THE
LOWER HALF OF FIGURE; 6, TANGENTIAL SECTION, X20; c, A FEW ZOGCIA OF THE SAME, X40, EXHIBITING
THE DARK DIVISIONAL LINE; d, VERTICAL SECTION, X20, SHOWING BIFOLIATE GROWTH AND SIMPLICITY
OF INTERNAL STRUCTURE. KEGEL LIMESTONE (D2), HABBINEM, ESTHONIA.

In thin sections the zoecial tubes are seen to arise rather abruptly
“from each side of the mesial lamina. As the surface is approached
their walls thicken slightly and the dark line separating adjoming
zocecia is developed. Vertical sections likewise indicate the absence
of diaphragms.

The dark divisional line is especially well shown in tangential sec-
tions, which exhibit also the simplicity of zoccial structure as a
whole. In figure 157 6, a few mesopores or interspaces are seen to
be limited to the macula of larger or more irregularly shaped cells,
while the zocecia proper are smaller and assume a quite hexagonal
outline.

The present species agrees in all respects with the Devonian forms
upon which the genus was based, indeed, it is quite close to Petalotrypa

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 267

delicata Ulrich from the Hamilton group of Iowa and Illinois. Care-
ful comparison shows that the latter has distinctly smaller zoccia.
Occurrence.—Rare in the Kegel limestone (D2) at Habbinem,
Esthonia.
Holotype.—Cat. No. 57371, U.S.N.M.

Family TREMATOPORID Ulrich.

Zoaria incrusting, ramose or massive. Zocecial tubes thin and
irregular in the axial region, usually constricted where diaphragms are
inserted. Walls thickened in the mature region, with a distinct
divisional line where the zowcia are in contact. Acanthopores more
or less abundant; mesopores often abundant and of large size, their
apertures closed.

Compared with the Halloporide this family differs most obviously
in having closed mesopores and ‘‘ beaded’”’ zocecial tubes caused by the
constriction of the walls when a diaphragm is inserted. With the
emendation of the Halloporide to include a species with a slight
development of acanthopores, the most noticeable distinction between
the two families—the presence of the structures in one and not in the
other—is less marked although still of value. Asa rule the Tremato-
porides have a general looseness and slight obscurity of structure
quite unlike that of any other family. For example, the walls are
not as clear and distinct as in the Amplexoporide or Halloporide,
the acanthopores have a less definite, clear cut structure, and the walls
are often undulating. It is difficult to describe this ‘‘ trematoporoid”’
structure, although it is usually recognized without difficulty after
one has learned it from experience.

The specific and generic representation of the Trematoporide is
the largest of the Trepostomata. All of the American genera save
one are represented, and, with further search, this exception, Stro-
matotrypa, will probably also be found common to both continents.
The unusually large specific development of Hemiphragma in European
strata is an interesting feature brought out by the present studies, and
indicates most decidedly the value of the semidiaphrams as a generic
character. .
Genus TREMATOPORA Hall.

Trematopora Hatt, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 400; Nat. Hist.
New York, Pal., vol. 2, 1852, p. 149.—Hatu and Simpson, Nat. Hist. New
York, Pal. vol. 6, 1887, p. xiv.—Mutizr, North Amer. Geol. and Pal., 1889,
p. 328.—Utricu, Geol. Surv. Illinois, vol. 8, 1890, pp. 373, 418; Geol. and
Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 308.—Smmpson, Fourteenth
Ann. Rep. State Geologist of New York for the year 1894, 1897, p. 591.—
NickeEs and Basster, Bull. 173, U. 8. Geol. Surv., 1900, p. 35.—Pocta,
Syst. Sil. du Centre Boheme, vol. 8, pt. 2, 1902, p. 314.—Bassier, Bull.
292, U.S. Geol. Surv., 1906, p. 43.

Not Trematopora of Ulrich, 1882; Eichwald, 1860; Dybowski, 1877.

At least 80 species of Paleozoic Bryozoa have been referred to
Trematopora, from time to time, but few of these are strictly con-

92602°—Bull. 77—11——19

268 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

generic with the genotype. Ulrich was the first to point out the
generic characters and to assign many of this large number of species
to more natural positions in the classification. |

In his later work, Ulrich has considered the genus as the Silurian
representative of Batostoma, and has suggested dropping the latter
name. The discovery of two new undoubted species of Trematopora
in the Middle Ordovician of Russia, in addition to the wide-spread
T. primigenia, and the occurrence of all three in association with
typical Batostoma, seems sufficient justification for the recognition
of both genera.

As indicated in the above synonymy, Dybowski misinterpreted the
genus entirely, all of the species referred to it by him proving to be
typical forms of his genus Dvttopora.

Internally the distinctly beaded mesopores, and, externally, the
solid zocecial interspaces and peristomes may be relied upon in dis-
tinguishing species of T’rematopora.

Genotype.—T rematopora tuberculosa Hall. Niagaran strata of the
United States and Canada.

TREMATOPORA PRIMIGENIA Ulrich.

Text fig. 158.

Trematopora primigenia Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 97.

Trematopora? primigenia Uiricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 309, pl. 21, figs. 23-40.

This abundant American Black River species is present among the
small bryozoans from the Wassalem beds at Uxnorm. Ulrich has
given a careful description of the Minnesota specimens which applies
equally well to the Russian examples, and it is therefore copied below.

Zoarium loosely bushy, consisting of small slender ramulets, dividing dichotomously
at varying intervals; branches cylindrical or compressed, commonly about 2 mm. in
diameter, but varying from 1.5 to 4 mm., arising in greater or lesser numbers from a
large basal expansion that is thinly spread over some cylindrical body like a crinoid
column. Not infrequently the branches inosculate freely. Entire zoaria varying
in diameter probably between 20 and 60 mm. Superficial aspect of zocecia varying
withage. In young stages or examples the apertures are more or less oblique, with only
the posterior border elevated and the interspaces in a varying degree narrower than
the apertures. With age the apertures become somewhat smaller, ovate or subcircular
and direct, and the peristome or rim equally elevated all around, while the inter-
spaces were widened till in some examples they are often equal to twice the width
of the zocecial orifices. At the same time the interspaces, which as a rule exhibit no
sign of the really very numerous mesopores, are roughened, as are also the peristomes,
by the development of acanthopores. These vary greatly in size and number. The
arrangement of the zocecial apertures is only moderately regular, there being here
and there spots in which they are of larger size and more widely separated than usual.
An average of 12 or 13 in 3 mm., but the number in that distance may vary from
11 to 15.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 269

Internal characters.—In vertical sections the tubes have thin walls, are not entirely
vertical, and without diaphragms in the axial region. Near the surface they bend out-
ward rather abruptly when one and sometimes two diaphragms were in most cases
thrown across each tube. At the same time an abundant series of mesopores was
developed. These are crossed by from two to six diaphragms, the outer ones of which
are much thicker and separated by shorter intervals than the inner pair. * * *
The walls of the mesopores where two or more occupy an interspace are strongly
zigzag, in some instances appearing not unlike vesicular tissue. In tangential sections
the zocecial walls may be thin and occasionally even inflected by the acanthopores,
but as a rule they are ring-like, and generally completely separated from each other

Fig. 158.—TREMATOPORA PRIMIGENIA. @ TO C, THREE FRAGMENTS, NATURAL SIZE; d, BASE OF A ZOARIUM,
LIFE SIZE; €, SURFACE OF A TYPICAL EXAMPLE, X9, SHOWING THE PERISTOME; /, SURFACE OF ANOTHER
SPECIMEN, X18, WITH NUMEROUS ACANTHOPORES AND OPEN MESOPORES; g, THE USUAL APPEARANCE
IN TANGENTIAL SECTION, X18; h, SEVERAL ZO@CIA OF THE SAME SECTION, X50; 7, VERTICAL SECTION,
X18, THROUGH A BASAL EXPANSION ATTACHED TO A CRINOID COLUMN. BLACK RIVER (DECORAH)
SHALE, MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

by a series of unequal and irregularly shaped mesopores. The acanthopores are dis-
tinct, nearly uniform in size, usually attached to the outer side of the zocecial walls,
and number from one to three or four to each zocecium.

Occurrence—Common in the Rhinidictya bed of the Black River
(Decorah) shale at various localities in Minnesota. Apparently rare
in the Wassalem beds (D3) at Uxnorm, Esthonia (Cat. No. 57372,
U.S.N.M.).

Specimens from American localities are in the collections of the
British Museum.

270 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

TREMATOPORA KUCKERSIANA, new species.

Text fig. 159.

Free examples of this fine new form have not been seen, the species
being founded upon specimens embedded in the solid limestone.
These, however, are well preserved and show the following char-
acters:

Zoarium of cylindrical branches 5 mm. in diameter, dividing infre-
quently. Surface smooth, with the usual macule of large zoccia
and wider interspaces. Zocecial apertures rounded to oval, with a
well-marked peristome. Six to seven zocecia In 2 mm., measuring
from the center of a macula. Acanthopores few. Mesopores numer-
ous, usually isolating the zocecia, but not visible at the surface where
their place is taken by tissue forming the solid interzocecial spaces
characteristic of the genus.

Fic. 159.—TREMATOPORA KUCKERSIANA, @, TANGENTIAL SECTION, X20, SHOWING OVAL ZO@CIA AND
DISTINCT PERISTOMES; b, VERTICAL SECTION, X20; c, ANOTHER VERTICAL SECTION, X20, SHOWING THE
BEADED MESOPORES WITH CYSTLIKE DIAPHRAGMS. JCUCKERS SHALE (C2), REVAL, ESTHONIA.

Vertical sections show the usual beaded mesopores with numerous
diaphragms, which, when unusually crowded, give a cystose structure
to the interzoccial spaces. As the surface is approached the meso-
pores become filled with a laminated tissue, which, in tangential or
surface views, appears as solid interspaces. The zocecia have thin
walls and no diaphragms in the immature region and slightly thick-
ened walls with only an occasional diaphragm in the mature zone.
The beaded mesopores, with their crowded, often cyst-like diaphragms,
and their outer filling of tissue, form the most important feature of
such sections.

Tangential sections through the outermost part of the zoarium show
oval to circular zocecia with distinct peristomes separated by solid
tissue, through which the outlines of the mesopores are sometimes
faintly visible. Deeper sections exhibit the mesopores more clearly,
but show less distinct peristomes.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 271

The large, rounded zocecia, distinct peristomes, solid interspaces,
and cylindrical branches are characters which will readily distinguish
this species. Certain species of Hallopora have a similar zoarium and
general aspect, but their mesopores are never closed at the surface.

Occurrence.—Rare in the Kuckers shale (C2) at Reval, and in the
Jewe limestone (D1), Baron Toll’s estate, in Esthonia.

Holotype-—Cat. No. 57373, U.S.N.M.

British Museum, thin sections of the type-specimen.

TREMATOPORA CYSTATA, new species.

Plate 11, fig. 25; text fig. 160.

Numerous well-preserved examples of this typical little Trema-
topora are in the collections before me, and all agree in the internal and
external features shown on plate 11, figure 25, and text figure 160.

Fic. 160.—TREMATOPORA CYSTATA. @ AND 6, TWO FRAGMENTS, NATURAL SIZE; c, TANGENTIAL SECTION,
X20, SHOWING OVAL ZOGCIA, DISTINCT PERISTOMES AND SMALL ACANTHOPORES; d, SEVERAL ZOGCIA,
X40; €, VERTICAL SECTION OF A BRANCH, SHOWING THE USUAL APPEARANCE, X20. KUCKERS SHALE
(C2), REVAL, ESTHONIA.

The zoarium is of small, cylindrical stems, 2 to 3 mm. in diameter,
which branch frequently and irregularly. The surface is smooth, but
has distinct macule of larger zocecia and wider interspaces, as shown
in figure 25 of plate 11. Acanthopores are rather numerous, although
not as abundant as in Trematopora primigenia. Vertical sections
show the most decided features of internal structure, the presence of
abundant cyst-like structures fillimg the mesopores. Near the sur-
face these are obscured or replaced by a dense, laminated tissue.
Six to seven zocecia occur in 2 mm.

Trematopora cystata is closely related to T. primigenia, but differs
in having large zoccia, less abundant acanthopores, and especially in
the numerous crowded, cyst-like diaphragms fillimg the mesopores.
Trematopora kuckersiana has larger zocecia, fewer acanthopores, and
a more robust zoarium.

272, BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Occurrence.—Abundant in the Kuckers shale (C2) at Reval; less
common in the Kegel limestone (D2) at Kegel, Esthonia; rare in the
limestone with Trinucleus seticornis near Hulterstad Church, island
of Oeland.

Cotypes.—Cat. No. 57375, U.S.N.M.

British Museum, specimens from Reval, Esthonia, and from the
island of Oeland.

Genus BATOSTOMA Ulrich.

Batostoma Uuricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 154.—
Foorp, Contr. Micro-Pal. Cambro-Sil., 1883, p. 17.—Mitter, North Amer.
Geol. and Pal., 1889, p. 294—U.ricn, Geol. Surv. Illinois, vol. 8, 1890, pp.
379, 459; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 288;
Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 275._Simpson, Four-
teenth Ann. Rep. State Geologist of New York for the year 1894, 1897,
p. 588.—Nicxuies and Basser, Bull. 173, U. 8. Geol. Surv., 1900, p. 35.—
Cumines, Thirty-second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907,
p. 740.

This genus is most prolific both in species and specimens, but seems
to be limited to Ordovician strata and to the Richmond formation
of the earliest Silurian. In America no less than a dozen species
have been described from the Middle Ordovician alone, and a number
of new forms are known. Four of these same forms occur in the
Russian deposits with a few new species. The essential characters
of the genus are embodied in the following description:

Zoarium irregularly ramose, branches arising from a large basal
expansion; zocecia with walls that are thin in the immature region,
much thickened and in sections appearing ring-like (but seldom in
contact) in mature region; diaphragms present; mesopores numerous
or few, irregular in size or shape; acanthopores usually of large size
and abundant, sometimes few.

Genotype.— Monticulipora (Heterotrypa) implicata Nicholson. Upper
Ordovician (Eden) of the Ohio Valley.

BATOSTCOMA MAGNOPORA Ulrich.
Text figs. 161, 162.

Batostoma magnopora Utricu, Geol. and Nat Hist. Surv. Minnesota, vol. 3,
pt. 1, 1898, p. 261, pl. 25, figs. 12-15.

Original description.—This is given by Ulrich as follows:

Zoarium ramose; branches large, subcylindrical, 8 to 15 mm. wide; surface elevated
at irregular intervals into low monticules, the latter broad and occupied by zocecia
a little larger than the average. Zocecia unusually large, about eight in 3 mm., their
apertures polygonal, the walls thin, with one or two small acanthopores to each
zocecium rising generally from the wall at some point between the angles of junction.
Many of the latter are occupied by small mesopores, but these are to be regarded as
comparatively very few and at all times difficult to distinguish externally.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 273

Internal characters —In tangential sections the tubes are polygonal and have rather
thin walls, in which the line of contact between adjoining tubes is distinctly preserved.

Mesopores few, small, chiefly at the angles of junction. Acanthopores small, incon-

Fic. 161.—BATOSTOMA MAGNOPORA. @, SMALL SPECIMEN OF NATURAL SIZE; 6, TANGENTIAL SECTION, X18;
C, PART OF AXIAL REGION IN TRANSVERSE SECTION, X18; d, VERTICAL SECTION OF ZOARIUM WITH A NAR-
ROW MATURE ZONE, X9. BLACK RIVER (DECORAH) SHALE, MINNEAPOLIS AND ST. PAUL, MINNESOTA.
(AFTER ULRICH.)

Fig. 162.— BATOSTOMA MAGNOPORA. @, A SMALL RUSSIAN EXAMPLE REFERRED TO THE SPECIES, NATURAL
SIZE; b, TANGENTIAL SECTION OF SAME SPECIMEN, X20; c AND d, VERTICAL SECTION, X10, AND A PORTION,
X20. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

spicuous. In vertical sections the tubes proceed toward the surface in a very gentle
curve until they enter the unusually narrow peripheral region, where the curve is
sufficiently accelerated to enable them to open at the surface with nearly direct

274 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

apertures. Diaphragms are very remote or wanting in the axial region, and not
numerous even in the peripheral portion. Here each tube presents from one to five,
separated by intervals of from one-half to one tube diameter. In the mesopores,
which appear to be very short, the diaphragms are much closer, with three or four in
0.5mm. Inthe central part of transverse sections the tubes are conspicuously divided
into a large and small set, both having very thin walls.

Occurrence-—The American types are from the Rhinidictya bed of
the Black River (Decorah) shales of Minnesota. In Russia the species
is known only from the Wassalem beds (D3) at Uxnorm, Esthonia.

Plesiotype.—Cat. No. 57377, U.S.N.M.

Thin sections of the Russian type are in the collections of the
British Museum.

BATOSTOMA FERTILE Ulrich.

Text fig. 163.

Batostoma fertilis Utricn, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minne-
sota, 1886, p. 92.

Batostoma fertile Unricn, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 290, pl. 25, figs. 1-11; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 275, fig. 459 B.

Original description.—Ulrich thus describes this species:

Zoarium attaining a large size, 50 to 100 mm. in height, consisting of strong, irregu-
larly thickened, more or less compressed branches that divide without regularity;
thickness of branches 5 to 25 mm., width 8 to 30 mm. Zocecial apertures varying
according to the size and number of the mesopores and the thickness of the walls,
from polygonal to circular. In some specimens and portions of others mesopores are
exceedingly few and the zocecial walls thin and generally in contact at all sides; in
the majority of examples mesopores are moderately abundant and the walls thicker,
but the zocecial apertures are still polygonal or at any rate most of them subangular.
From this, the typical form, we can trace the variations by small degrees into a form
which, for the sake of reference, may be designated as var. circulare. In this the zoo-
cial apertures are almost perfectly circular, inclosed by a raised rim or peristome, and
largely separated from each other by depressed interspaces. * * * Interspaces
occupied by mesopores varying considerably in size and shape. Their mouths are
commonly closed by a calcareous plate in which a variously situated rounded opening
may be observed. When the preservation is unusually favorable the surface of the
plate is studded with very minute papille representing the terminations of exceed-
ingly small foramina. Acanthopores between one and two to each zocecium, but
very small and only in rare instances distinguishable at the surface. At intervals
of 3 or 4mm. occur clusters of zocecia a little larger than the average, and in the center
of these usually small substellate macule. Between eight and nine of the average
zocecia in 3 mm.

Internal characters: In vertical sections the tubes have thin and somewhat irregu-
larly fluctuating walls in the axial region. Their course to the surface is gently curved
throughout, and as they near the same their walls are appreciably thickened, while
mesopores, whose number varies greatly in different specimens, are abruptly devel-
oped. The mesopores may be constricted at the points where they are intersected
by the diaphragms. The latter are often thickened circumferentially, and vary some-
what in the number occurring in a given space, seven and eleven in 1 mm. being
the extremes so far noticed. In the axial region diaphragms are very far apart or
are wanting entirely, but in the peripheral portion the average distance between
them is about equal to half their diameter. Specimens more than 12 mm. thick
consist of two or more layers of tubes.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 275

In the above description Ulrich has embodied all of the essential
features of the species. The Russian examples referred here are so
similar externally and internally that there can be little doubt of the
correctness of their reference to Batostoma fertile.

age

Fic. 163.—BATOSTOMA FERTILE. @ AND 6b, A LARGE AND A SMALL SPECIMEN, NATURAL SIZE; c, SURFACE
OF THE LARGER SPECIMEN, X9; d, TANGENTIAL SECTION OF THE SAME EXAMPLE, X18; €, VERTICAL SEC-
TION, NATURAL SIZE, AND A PORTION, X18. BLACK RIVER (DECORAH) SHALES, MINNEAPOLIS, MINNE-
soTa. (AFTER ULRICH.)

Occurrence—Common in the Stictoporella bed of the Black River
(Decorah) shales of Minnesota; rare in the Echinospherites lme-
stone (C1) near Reval, Esthonia (Cat. No. 57378, U.S.N.M.).

American specimens of the species are in the collections of the British
Museum.

BATOSTOMA FERTILE CIRCULARE Ulrich.

Text fig. 164.

Batostoma fertile var. circulare Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol.
3, pt. 1, 1893, p. 291, pl. 25, figs. 8, 9; Zittel’s Textbook of Paleontology
(Eng. ed.), 1896, p. 275, fig. 459 B.

The distinctive feature of this variety is pointed out in the above
description, and illustrated in the accompanying figure, although
often the peristomes are thicker and more distinctly separated from
each other than is shown in the figure. Both species and variety
are found associated in American strata and likewise in the Russian.

276 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Occurrence.—Abundant in the Stictoporella bed of the Black River
(Decorah) shale in Minnesota; rare in the Echinospherites limestone
(C1), near Reval, Esthonia (Cat. No. 57379, U.S.N.M.).

ae

Fic. 164.—BATOSTOMA FERTILE CIRCULARE. @ AND b, SURFACE OF A TYPICAL EXAMPLE, X9, WITH A POR-
TION, X18; c AND d, TWO TANGENTIAL SECTIONS, X18, FROM DIFFERENT PARTS OF THE MATURE ZONE.
BLACK RIVER (DECORAH) SHALES, MINNEAPOLIS, MINNESOTA. (AFTER ULRICH.)

American specimens of the species are in the collections of the
British Museum.

BATOSTOMA MICKWITZI, new species.
Plate 10, figs. 3-6; text fig. 165.

This striking bryozoan may be easily recognized by its unusually
robust branches, very large polygonal zocecia and few mesopores.
In size of zoarium the species is approached by no other of the known
Paleozoic ramose bryozoans, while such unusually large zocecia are
found in but few branching species. The small fragment figured
on plate 10 averages 25 mm. in diameter, but the more complete
zoarium illustrated has branches 40 mm. in diameter, increasing to
70 mm. just before a bifurcation. This latter specimen, and another
showing the basal portion clearly, indicate that the complete zoarium
consisted of a stout, slightly spreading basal portion arising into a
short, cylindrical stem, which, after a growth of 60 mm. or more,
divided dichotomously. After a growth for a similar distance, each
of these divisions branches in the same way, but after this second
branching, zoarial growth seems to have stopped. An entire zoarium
was therefore probably seldom over 150 mm. in height.

Surface of a zoarium smooth, macule scarcely distinguishable
with the naked eye, but under a hand lens they are seen to be com-
posed of the usual large zocecia and more numerous mesopores.
Zocecia angular, unusually large, four to four and one-half in 2 mm.;
an ordinary zocecium averages 0.5 mm. in diameter, while the largest
zocecia of the macule are one-half again as large. Zocecial walls
thin; acanthopores apparently seldom developed, probably repre-
sented by knot-like structures in the cell angles; mesopores few,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 277

generally entirely absent in the intermacular areas and occurring
only sparingly in the macule.

In vertical sections the tubes in the immature zone have thin,
somewhat flexuous walls and are crossed by very few diaphragms.

Fic. 165.—BATOSTOMA MICKWITZI. @, TANGENTIAL SECTION, X20, SHOWING WALL STRUCTURE AND SIZE
OF ZOG@CIA, RANGING FROM THE LARGE ONES OF THE MACULA TO THE SMALLER ORDINARY ONES; 0, VER-
TICAL SECTION, X8, THROUGH BOTH REGIONS AND WITH A SECOND GROWTH OF ZOG@CIA; Cc, SEVERAL TUBES
OF THE MATURE ZONE, X20, IN VERTICAL SECTION; d, VERTICAL SECTION, X20, SHOWING STRUCTURE OF
WALLS IN THE IMMATURE ZONE. WASSALEM BEDS (D3), UXNoRM, ESTHONIA.

The curve to the surface is gentle and the mature region is distin-
guished principally by the more abundant diaphragms and slightly
thicker walls. In the most crowded portion of the tubes three dia-
phragms occur in their own diameter, but one to two in this distance
is more often the rule.

278 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In the size of its zoccia alone this species is so decidedly ~ different
from other ramose Trepostomata that comparisons are unnecessary.
The specific name is in honor of the late Dr. August von Mickwitz,
who collected the type-specimens.

Occurrence.—Common in the Wassalem beds (D3) at Uxnorm,
Esthonia.

Cotypes.—Cat. No. 57380, U.S.N.M.

Thin sections of the type-specimens and two specimens from the
type locality are in the collections of the British Museum.

BATOSTOMA WINCHELII (Ulrich).

Text fig. 166.

Amplexopora winchelli Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 91.

Batostoma winchelli Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 295, pl. 26, figs. 33-37; pl. 27, figs. 1-6.—Simpson, Fourteenth Ann.
Rep. State Geologist of New York for the year 1894, 1897, p. 588, fig. 174.

Fig. 166.—BATOSTOMA WINCHELLI. @ AND 6, TWO FRAGMENTS OF NATURAL SIZE; C, SURFACE OF @, X9
AND X18; d, TANGENTIAL SECTION, X18, SHOWING CHARACTER OF A MATURE EXAMPLE; €, SMALL POR-
TION OF A TANGENTIAL SECTION OF A YOUNG SPECIMEN, X18; {, SEVERAL ZOG@CIA OF FIGURE d, X50;
g, VERTICAL SECTION, X18, OF AN ORDINARY SPECIMEN. BLACK RIVER (DECORAH) SHALE, ST. PAUL,
MINNESOTA. (AFTER ULRICH.)

The Russian specimens referred to this abundant American species
show external and internal features so similar to those figured below
that the illustrations of the American form will serve for both. The
following are the essential characters of the species:

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 279

Zoarium of irregularly ramose, subcylindrical, smooth branches,
‘usually 5 to 7 mm. in diameter. Zocecial apertures subangular,
somewhat irregularly arranged, seven to eight in 2 mm., with moder-
ately thick walls, ridge shaped when perfect, and with acanthopores
at the angles of junction. Mesopores few and irregularly developed.
_ The internal structure is well illustrated in the accompanying
figure, which is copied from Ulrich. The zoccia are smaller than in
any of the other species of the genus, and this, in addition to their
shape, will aid in identification.

Occurrence.—Common in the Rhinidictya bed of the Black River
(Decorah) shales of Minnesota; apparently rare in the Jewe beds (D1)
at Paeskiill (Cat. No. 57381, U.S.N.M.), and in the Wesenberg lime-
stone (EK) at Wesenberg, Esthonia (Cat. No. 57382, U.S.N.M.)

British Museum, specimen and thin section from Paeskill, Esthonia.

Fic. 167.—BATOSTOMA WINCHELLI SPINULOSUM. @, A RUSSIAN EXAMPLE, NATURAL SIZE; b, TANGENTIAL
SECTION, X20, SHOWING THICK WALLS AND FEWER LARGER ACANTHOPORES THAN USUAL; c, SEVERAL
ZOCCIA OF ANOTHER TANGENTIAL SECTION OF THE SAME SPECIMEN, X20, EXHIBITING THE NORMAL DEVEL-
OPMENT OF ACANTHOPORES NOTED IN AMERICAN EXAMPLES; d, VERTICAL SECTION, X20. WASSALEM
BEDS (D3), UXNoRM, ESTHONIA.

BATOSTOMA WINCHELLI SPINULOSUM Ulrich.
Text figs. 167, 168.

Batostoma winchelli var. spinulosum Uuricu, Geol. and Nat. Hist. Surv. Minne-
sota, vol. 3, pt. 1, 1893, p. 296, pl. 27, figs. 7, 8; Zittel’s Textbook of Paleon-
tology (Eng. ed.), 1896, p. 275, fig. 459 C.

In the typical form of this species the acanthopores are small or
only of medium sive, and are numerous enough to occupy nearly all
the junction angles. The present variety was distinguished by Ulrich
to include those specimens having the same general zoarial and
zocecial characters except that the acanthopores are much stronger
and the zoccia are a trifle larger. Tangential sections prepared

280 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

from American specimens are shown in figure 168 for comparison
with the Russian specimens referred to the variety. The thin sec-
tions of the particular specimen illustrated in figure 167 show
unusually large and few acanthopores, but other sections of the same
example show them of the more usual size and number.

Occurrence—Common in the Black River (Decorah) shales of
Minnesota; apparently rare in the Wassalem bed (D3) at Uxnorm,
Esthonia.

Plesiotype.—Cat. No. 57383, U.S.N.M.

Thin sections of the Russian example are in the collections of the
British Museum. -

Fic. 168.—BATOSTOMA WINCHELLI SPINULOSUM. @ AND 0, TANGENTIAL SECTION, X18, AND A SINGLE ZOG-
cluM, X50, WITH NUMEROUS ACANTHOPORES. BLACK RIVER (DECORAH) SHALES, ST. PAUL, MINNE-
SOTA. (AFTER ULRICH.)

BATOSTOMA GRANULOSUM, new species.

Text fig. 169.

Only two examples of this form are known to me, but its large
zocecia and numerous large acanthopores, in addition to its internal
structure, form a combination of characters so different from other
species of Batostoma that I do not hesitate to describe it as new.
The example on which the description is based is a cylindrical stem
8 mm. in diameter, most of which has been used in making the thin
sections studied. Its surface is free from monticules but granulose
because of the numerous acanthopores. Zoccia thick-walled,
irregularly polygonal with occasional mesopores. Acanthopores
large and numerous, eight usually surrounding a zoccium. Three
and one-half to four zocecia in 2mm. Macule of larger zocecia and
more abundant mesopores a conspicuous feature of the surface and
of thin sections.

The internal structure is that of a typical Batostoma. In the
vertical section figured the mature region is short and little devel-
oped, but the beaded mesopores and usual wall structure of the genus
are apparent. Tangential sections bring out the numerous large
acanthopores very plainly and show in addition rather few mesopores.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 281

Altogether the numerous large acanthopores will distinguish this from
other species of the genus which have equally large zocecia. A very
similar, undescribed, or possibly the same species, is present in the
Black River rocks of America.

Occurrence.—Rare in the Jewe limestone (D1), Baron Toll’s
estate, near Jewe, Esthonia, and in the Itfer limestone (C3), north of
Wesenberg, Esthonia.

Holotype-—Cat. No. 57384, U.S.N.M.

British Museum, thin sections of the type-specimen, and a speci-
men from the Itfer limestone, north of Wesenberg.

Fic. 169.—BATOSTOMA GRANULOSUM. @, THE SECTIONED TYPE-SPECIMEN, NATURAL SIZE; 6, TANGENTIAL
SECTION OF MATURE ZONE, X20, SHOWING NUMEROUS GRANULE-LIKE ACANTHOPORES; ¢, VERTICAL SEC-
TION, X20, WITH THE MATURE ZONE ONLY A LITTLE DEVELOPED. JEWE LIMESTONE (D1), BARON
TOLL’S ESTATE, ESTHONIA.

Genus HEMIPHRAGMA Ulrich.

Batostoma (part) Uricu, Geol. Surv. Illinois, vol. 8, 1890, p. 379.

Hemiphragma Uuricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893,
p. 299; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 275.—Smpson,
Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897,
p. 592.—Nicxues and BasstzER, Bull. 173, U. S. Geol. Surv., 1900, p. 35.

The genus Hemiphragma was established by Ulrich to include four
American species apparently closely related to Batostoma, but differ-
ing in having incomplete instead of complete diaphragms in their
mature region. A ramose form, Batostoma irrasum Ulrich, occurring
in the Middle Ordovician strata of Minnesota and Iowa, was selected
as the genotype, and its style of growth was regarded as a generic
characteristic. Since that time a fifth ramose species, Monticulipora
whitfieldt James, from the Eden division of the Cincinnatian rocks,

282 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

has been assigned to the genus, and at least four undescribed branch-
ing forms have been discovered. In addition to this four American
species with the same structural features of incomplete diaphragms,
but with a massive form of growth, are awaiting description. The
genus Hemiphragma is therefore represented in America by no less
than thirteen species. The occurrence of ten species in the Middle
Ordovician of Russia and Sweden, seven of which are new, is an
interesting addition to our knowledge of the genus, and, as noted
before, emphasizes the value of incomplete diaphragms as a generic
feature.

Genotype.—Batostoma irrasum Ulrich. Middle Ordovician (Black
River) of Minnesota and Iowa.

Fic. 170.—HEMIPHRAGMA TENUIMURALE. @, THE RUSSIAN EXAMPLE SECTIONED, NATURAL SIZE; 6, VIEW
OF TANGENTIAL SECTION THROUGH THE OLDEST PART OF THE MATURE ZONE; C, VERTICAL SECTION, X20.
WASSALEM BEDS (D3), UXNoRM, ESTHONIA. =

HEMIPHRAGMA TENUIMURALE Ulrich.
Text figs. 170, 171.

Hemiphragma tenuimurale Unricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 301, pl. 24, figs. 20-23.

The following remarks, although based on the Russian specimens
of this species, apply also to the American types.

Zoarium of small, irregularly dividing branches, 6 to 10 mm. in
diameter; surface smooth with inconspicuous macule of zoccia
larger than usual; zocecial tubes polygonal, thin-walled; five to six
zocecia in 2 mm.; mesopores few, restricted almost entirely to the
macule; no acanthopores observed.

- EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 283

The most important internal features are shown in vertical sections
where the thin, irregularly fluctuating walls and the rather numerous
incomplete diaphragms, with as many as three in a tube diameter in
the mature zone, are the most important points to be noted. The
zocecial walls in the mature zone are but slightly thickened, differing
in this respect from nearly all other ramose species of Hemiphragma.
The particular thin section figured shows incomplete diaphragms at
distances ranging from one to two tube diameters in a portion of the
immature region.

In general zoarial and zocecial characters these Russian examples
are practically identical with the abundant American form from the
Clitambonites and Nematopora beds of the Lower Trenton in Minne-
sota. Indeed, the only difference noted at all was the occurrence of

Fig. 171.—HEMIPHRAGMA TENUIMURALE. ULRICH’S VIEWS OF THE MINNESOTA TYPES. @, SURFACE OF
SPECIMEN SHOWING THE SEMIDIAPHRAGMS IN THE ZOGCIAL CAVITIES, X9; 6, VERTICAL SECTION, X18;
Cc, TANGENTIAL SECTION, X18, SHOWING THE FULLY MATURED CONDITION. LOWER BEDS OF THE
TRENTON LIMESTONE, NEAR CANNON FALLS, MINNESOTA.

a few incomplete diaphragms in the immature zone of the Baltic
specimens. Such an occurrence is known in old examples, particu-
larly at the base of a zoarium, and it is evident that the particular
sections figured were obtained from such specimens.

The ramose habit of growth, thin-walled, polygonal zoccia, few
mesopores, and especially the numerous incomplete diaphragms of
the mature region, are characters which will distinguish H. tenwi-
murale from associated forms. Comparison of figures 170 and 171
will show the practical identity of internal structure in the Russian
and American specimens.

Occurrence.—Common in the Clitambonites and Nematopora beds
of the Lower Trenton at various localities in Minnesota and Iowa.
Rare in the Wassalem bed (D3) at Uxnorm, near Reval, Esthonia.

Plesiotype.—Cat. No. 57416, U.S.N.M.

British Museum, a thin section of the Russian type.

92602°—Bull. 77—11——20

284 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

HEMIPHRAGMA IRRASUM (Ulrich).
Text figs. 172, 173.

Batostoma irrasa Utricy, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minnesota,
1886, p. 94. 3
Hemiphragma irrasum Urricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 299, pl. 24, figs. 5-19; Zittel’s Textbook of Paleontology (Eng. ed.),
1896, p. 275, fig. 460.—Smrson, Fourteenth Ann. Rep. State Geologist ol

New York for the Year 1894, 1897, p. 592, figs. 190-193.

This very abundant American Black River species is represented
in the Russian collection by a large zoarium which, as a comparison
of figures 172 and 173 will show, has a structure practically identical

3 vy j ie yen
Fic. 172.—HEMIPHRAGMA IRRASUM. f, VIEWS OF THE MINNESOTA TYPES, AFTER ULRICH. @ AND b, TWO
FRAGMENTS, NATURAL SIZE, SHOWING DIFFERENCE IN SIZE AND BRANCHING; C, SURFACE OF AN AVER-
AGE EXAMPLE, X9; d AND €, TANGENTIAL SECTIONS, X18, EXHIBITING RANGE OF STRUCTURE NOTED IN
VARIOUS PARTS OF THE ZOARIUM; f, VERTICAL SECTION OF BRANCH, X9. BLACK RIVER (DECORAH)

SHALES, MINNEAPOLIS, MINNESOTA.

with that of Ulrich’s types. In fact, this specimen differs only in the
greater size of its branches, a difference due entirely to age. Ulrich
has given the following description of Hemiphragma irrasum:

Zoarium consisting of small, subcylindrical, frequently and rather irregularly divid-
ing branches, commonly 5 or 6 mm. in diameter, but varying from 4 to 8 mm., the
latter extreme probably only when an extra layer of tubes has grown over the original
branch. Monticules wanting, but under fully matured conditions the surface is abun-
dantly spinulose. Zocecia with subangular apertures.and thin walls when young,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 285

and with smaller, subcircular or oval apertures and more or less thick walls in fully
matured examples; arrangement of apertures rather regular in rows about small solid
spots, in the immediate vicinity of which the zocecia may be of larger size than else-
where; seven to nine in 8 mm. Interspaces apparently solid and generally with
shallow irregular depressions in most specimens, but in very young stages a variable
number of irregular mesopores may be recognized. Acanthopores numerous, two or
more to each zocecium, situated in the angles of junction and interspaces, and increas-
ing in size with age. They are large and a conspicuous external feature of well-pre-
served mature examples.

Fic. 173.—HEMIPHRAGMA IRRASUM. @, VIEW, NATURAL SIZE, OF THE LARGE, IRREGULARLY BRANCHING
BASAL PORTION OF A ZOARIUM; 6, TANGENTIAL SECTION OF THE SAME SPECIMEN, X20; c, SEVERAL ZOG-
CIA, X35, ILLUSTRATING THE MINUTE WALL STRUCTURE; d VERTICAL SECTION, X20, PASSING THROUGH
BOTH REGIONS. ORTHOCERAS LIMESTONE (B3), BALTISCHPORT, ESTHONIA.

Internal characters.—In the axial region of vertical sections the tubes have thin and
irregularly fluctuating walls and few or no diaphragms. The latter are complete here
and the proximal end of the tube expands to full size with unusual rapidity. In the
peripheral region, which is narrow and abruptly distinguished from the axial, the
walls are more or less thickened, and the tubes intersected by semidiaphragms,
about fourin 0.5mm. [ have satisfied myself that all the transverse partitions in
this outer part of the zoccial tubes are really incomplete. That many may appear
entire in sections is only because their inner edge happens to be vertical instead of
horizontal. Mesopores are difficult to make out in these sections, being short and
usually filled, in part at least, with solid tissue. Tangential sections require no descrip-
tion, all the essential characters being shown in the figures.

286 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Occurrence.—In America, common in most of the subdivisions of
the Black River (Decorah) shales in Minnesota and Jowa and in the

Clitambonites bed of the Lower Trenton of the same states. Appar-.

ently rare in Russia, the only known specimen being from the Ortho-
ceras limestone (B3), near Baltischport, Esthonia.

Plesiotype.—Cat. No. 57417, U.S.N.M.

British Museum, thin section of the Russian type.

LL 4
Fic. 174.—HEMIPHRAGMA PANDERI. a, VERTICAL SECTION, X20, SHOWING THE LARGE, THICK SEMI-

DIAPHRAGMS; 6, THE USUAL VIEW SEEN IN TANGENTIAL SECTION, X20; c, PORTION OF SAME, X40, SHOWING
STRUCTURE OF WALLS AND ACANTHOPORES. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

HEMIPHRAGMA PANDERI (Dybowski).
Plate 3, figs. 9-9c; text fig. 174.

Orbipora pandert DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-Formation,
1877, p. 66, pl. 2, figs. 9-9c.

Cir. Hemiphragma ottawaense (FoorD), Contr. Micro-Pal. Cambro-Sil., 1883, p. 18,
pl. 2, figs. 1-1f.

Dybowski has given sufficient illustrations of this fine species (see
pl. 3, figs. 9-9c) to make its identification easy, and the additional
figures here presented are introduced to exhibit features of internal
structure not shown by the author of the species. As Dybowski’s
figures show, the species is an undoubted typical Hemiphragma, and
to one acquainted with American forms its resemblance to Hemi-
phragma ottawaense (Foord), from the lowest Trenton of Canada, is
very striking. This resemblance is most marked in the surface
features of the zoarium and in the internal structure seen in vertical
sections. Tangential sections show, however, that the Russian spe-
cies has more angular zocecia, more numerous and more regularly
arranged acanthopores, and fewer mesopores or closed interspaces.
Thus, while the two are closely related, and possibly one is only a

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 287

variety of the other, an examination of the magnified surface will
distinguish them. The characters of Hemiphragma panderi are as
follows:

Zoarium of stout, cylindrical, rather infrequently dividing branches,
averaging 10 mm. in diameter. Surface smooth, with conspicuous
_ macule composed of thick-walled mesopores and zocecia larger than
usual or of aggregations of mesopores completely filled with a dense
tissue. The latter arrangement in the macule forms the spots well
shown in Dybowski’s figure. These macule are either level with the
surface or are slightly sunk beneath the plane of the ordinary zocecia.
Zocecial apertures subangular, thick walled, and exhibiting numer-
ous blunt acanthopores on the walls and on the closed mesopores
forming the macule. Six zocecia in 2mm. Mesopores few, seldom
more than one to a zomcium, and usually closed at the surface.
Acanthopores of medium size, but so numerous that 20 to 24 some-
times surround a zocecium.

The internal structure is so distinct that a description, in addition
to the figures, is hardly necessary. Vertical sections show charac-
teristic incomplete diaphragms very distinctly. In this species cross
partitions of any kind are absent in the immature zone, and semi-
diaphragms are first inserted in the bend to the mature region. In
the latter region proper they are well developed both in size and
number. The especial features of tangential sections are the angu-
lar, thick-walled zocecia, the numerous acanthopores, and the scarcity
of mesopores.

Occurrence.—Common in the Kuckers beds (C2) and apparently
rare in the Jewe limestone (D1), Baron Toll’s estate, Esthonia.

Plesiotype.—Cat. No. 57418, U.S.N.M.

British Museum, specimens and thin sections from the Kuckers
(C2), Baron Toll’s estate.

HEMIPHRAGMA GLABRUM, new species.

Plate 10, fig. 1; text fig. 175.

Zoarium ramose, of smooth, slender, cylindrical, frequently dividing
branches, 3 to 4 mm. in diameter. Macule composed of thick-
walled mesopores, a conspicuous feature of the surface under the
hand lens but less noticeable to the unaided eye. Zocecial apertures
subangular, thick-walled, frequently separated by mesopores with
walls of equal thickness. About seven zoccia in 2mm. Acantho-
pores very inconspicuous or wanting.

In the axial region of vertical sections the zoccial tubes have
strongly crenulated or fluctuating walls, and are not crossed by
partitions save an occasional semidiaphragm developed usually in the
bend to the mature zone. The zoccial walls become thicker and less

288 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

crenulated in the mature region where the thickness is again increased
by the deposition of solid tissue along their sides. Here diaphragms
are more numerous and nearly always appear to be complete. In the
mesopores diaphragms occur at intervals of one-half their diameter
apart. Frequently the mesopores become filled with solid tissue to
such an extent that they are indistinguishable in sections and form
solid interspaces at the surface.

Fic. 175.—HEMIPHRAGMA GLABRUM. @ AND b, TWO FRAGMENTS, NATURAL SIZE; C, BASAL PORTION OF A
ZOARIUM, NATURAL SIZE; d, TANGENTIAL SECTION, X20, EXHIBITING THICK-WALLED, ANGULAR ZOGICIA
AND MESOPORES; €, VERTICAL SECTION, X20, SHOWING FEWER SEMIDIAPHRAGMS THAN USUAL; jf, SEV-
ERAL ZOGCIA OF A TANGENTIAL SECTION, X35, ILLUSTRATING WALL STRUCTURE. WASSALEM BEDS (D3)
UXNORM, ESTHONIA.

' The internal structure of numerous specimens of this well-marked
species has been studied and the usual characters are illustrated in
figure 175. In figure 175 e the semidiaphragms are not as numerous
as in other vertical sections while the complete diaphragms are more
abundant. It is probable that most of the latter are in reality incom-
plete and only appear complete because of the way they are cut by
the section.

Externally the slender, branching,smooth stems with thick-walled
zocecia and mesopores, and internally the strongly crenulated walls.
of the immature region, and the occurrence of semidiaphragms are
characters which will aid in separating the present species from asso-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 289

ciated ramose bryozoans. The thick-walled subangular zoccia and
mesopores, practical absence of acanthopores, and the few semidia-
phragms will separate it from other species of the genus.
Occurrence—Not uncommon in the Wassalem beds (D3) at
Uxnorm, Hsthonia.
Cotypes.—Cat. No. 57420, U.S.N.M.

British Museum, one specimen and one thin section.

Fic. 176.—HEMIPHRAGMA PYGMUM. Q, SIDE VIEW OF A TYPICAL SPECIMEN, X2; 0, AN ORDINARY TAN-
GENTIAL SECTION, X20, SHOWING THE CONSPICUOUSLY LARGE, NUMEROUS ACANTHOPORES; C, PORTION
OF THE SAME, X35, WITH MORE DETAILED STRUCTURE OF THE ACANTHOPORES AND WALLS; d, VERTICAL
SECTION, X20, WITH CHARACTERISTIC TABULATION. CHASMOPS LIMESTONE, SOUTH OF BODAHAMN,
ISLAND OF OELAND.

HEMIPHRAGMA PYGMUM, new species.

Text fig. 176.

In the collection made by Dr. Bather from the Chasmops limestone,
near Bédahamn, Oeland, are several specimens of a small, massive
Hemiphragma, which proved upon study to have some very striking
internal characters. The zoarium of the specimens observed is of
small pedunculate masses about 8 mm. in height and the same meas-
urement in their greatest width. The general shape of the zoarium,
as well as the smooth surface of one of the types, is shown in figure
176 a. Macule are observed with difficulty at the surface, the most
striking feature here being rather small, polygonal to rounded zoecia,
numerous angular mesopores, and many large conspicuous acantho-

290 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

pores. The latter form the most noticeable character in thin se¢-
tions, where, in the tangential especially, they are so large that
the place of an ordinary mesopore is often occupied by one. Four
acanthopores usually surround a zocecium, although six or seven
sometimes occur. Mesopores are likewise numerous and so large that
in tangential sections they are often distinguished from the true
zocecia with difficulty. In vertical sections the difference in tabula-
tion will of course readily distinguish the two. The walls of both
zocecia and mesopores are quite thick for such a form of growth, in
fact, with the exception of size of zoarium, H. pygmxeum is an
exceptionally well developed species. The tabulation of zocecia and
mesopores is shown in figure 176 d, while an idea of the relative size
arrangement, and number of mesopores as well as the structure of walls
and acanthopores may be had from figures 176 0b. and e.

None of the other species of Hemiphragma has such well developed
acanthopores, and this character alone will serve to distinguish the
species.

Occurrence-—Apparently rare in the Chasmops limestone near
Bédahamn, island of Oeland, Sweden.

The figured type and thin sections are in the collection of the
British Museum.

HEMIPHRAGMA MULTIPORATUM, new species.
Text fig. 177.

Although but a few examples of this species have been seen, its
characters are so distinct from all other species of the genus that no
difficulty should arise in distinguishing it. The zoarium in the type-
specimen is a flattened, hemispheric mass, which, before thin sections
were cut from it, was 20 mm. in diameter and about 7mm. high. As
usual in zoaria of this shape, the base is slightly concave with a con-
centrically wrinkled epitheca. The celluliferous surface is smooth
but shows distinct macule composed entirely of mesopores, at
intervals of 4 mm., measuring from center to center. The zoecial
apertures are thin-walled, polygonal, and are completely isolated by
one to three rows of angular mesopores. About four zocecia occur
in 2 mm., although the diameter of a single zoccium averages 0.30
mm. Acanthopores are absent entirely, but mesopores are exceed-
ingly abundant. In the macule seven rows of mesopores may be
counted, but in the intermacular spaces one or two rows usually
separate neighboring zocecia.

Excepting the numerous mesopores, the internal structure is quite
similar to other massive forms of the genus. The mesopores are
closely tabulated with straight partitions, while the zoccia have the
usual semidiaphragm projecting from either wall and averaging two
in a tube diameter in the crowded portions. The very numerous
mesopores, however, form the most striking feature of both vertical

EARLY PALEOZOIG BRYOZOA OF THE BALTIC PROVINCES. 291

and tangential sections. Another characteristic of the mesopores is
their comparatively straight walls which are in contrast with those
of other species of the genus.

The hemispheric growth, great abundance of mesopores, large,
distinct maculz, absence of acanthopores, and the distinct tabulation
of both zocecia and mesopores, form a combination of characters

which amply distinguish the present form.

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Fic. 177.—HEMIPHRAGMA MULTIPORATUM. @, SIDE VIEW OF THE TYPE-SPECIMEN BEFORE SECTIONING;
b, TANGENTIAL SECTION, X8, SHOWING A MACULA IN THE LOWER PART OF THE FIGURE; C, PORTION OF
THE SAME, X20, WITH THE MESOPORES SHADED TO DISTINGUISH THEM FROM THE ZOGCIA; d, VERTICAL
SECTION, X20, INCLUDING A MACULA; €, A PART OF THE SAME SECTION, X20, SHOWING THE DIFFERENCE
IN TABULATION BETWEEN ZOG@CIA AND MESOPORES. KUCKERS SHALE (C2), BARON TOLL’S ESTATE,

ESTHONIA.
Occurrence.—Rare in the Kuckers shale (C2), Baron Toll’s estate,
Esthonia, and in the Echinospherites limestone (C1), at Duboviki,
on the Wolchow River, government of St. Petersburg.
Holotype.—Cat. No. 57421, U.S.N.M.
British Museum, thin section of specimen from the Kuckers shale,

Baron Toll’s estate.

292 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

HEMIPHRAGMA SUBSPHERICUM, new species.
Plate 10, fig. 2; text figs. 178, 179.

Zoarium massive, quite variable in shape, but usually of irregular
subspherical masses, several centimeters in diameter.. Young
examples are often uniformly rounded, but in older examples, where
the growth is less regular, the zoarium is somewhat irregular, and

Fig. 178.—HEMIPHRAGMA SUBSPHERICUM. @ AND b, TWO PORTIONS OF A TANGENTIAL SECTION, X20 AND
X8, IN EACH CASE CUTTING A MACULA; C, ZO@CIA OF THE SAME SECTION, X40, ILLUSTRATING THE EX-
TREMELY THIN SIMPLE WALLS; d, VERTICAL SECTION, X8, PASSING THROUGH SEVERAL SUCCESSIVE
IMMATURE AND MATURE REGIONS; €, PART OF THE SAME SECTION, X20, SHOWING WALLS AND SEMI-
DIAPHRAGMS MORE CLEARLY. WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

may attain a diameter of 5 or6 cm. The zoarial surface is smooth,
but clusters of large zocecia forming the macule occur at intervals
of 5 mm. and are visible to the unaided eye. Zoccial apertures
direct, thin-walled, angular, and in contact, fivein 2mm. Mesopores
few, often entirely wanting; acanthopores absent.

In vertical sections of a large specimen the zoarium is seen to be
made of a number of zoccial layers, each of which shows an immature

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 293

region where the walls are thin, and semidiaphragms are far apart,
and a mature zone conspicuous for its crowded partitions and slightly
thicker walls. Two such layers are shown in the accompanying
illustration (fig. 178 d), while a more magnified view of a mature zone
and part of an immature zone is shown in figure 178 c. The occur-
rence of incomplete diaphragms throughout the zoccial tubes and the
practical absence of small, beaded tubes with straight partitions
may be seen in such sections. The arrangement and abundance
of the semidiaphragms is about the same in this species as in the
other massive forms, H. rotundatum and H. pygmexum, but an especial

a i

Fic. 179.—HEMIPHRAGMA SUBSPHERICUM. FOUR VIEWS OF ZOARIA, NATURAL SIZE. @, SIDE VIEW OF A
SPECIMEN COMPOSED OF TWO ROUNDED ZOARIA GROWING TOGETHER; b, SIDE VIEW OF A LONGER, MORE
FLATTENED SPECIMEN; c, A ROUNDED, SOMEWHAT IRREGULAR EXAMPLE; d, BASAL VIEW OF SPECIMEN,
SHOWING CICATRIX OF GASTROPOD UPON WHICH GROWTH COMMENCED. WESENBERG LIMESTONE (E),
WESENBERG, ESTHONIA.

point of difference is the crenulation of the tubes in H. subsphericum.
This latter feature is likewise shown in vertical fractures of the
zoarium.

Tangential sections bring out the extreme simplicity and thinness
of the zoccial walls and the absence of acanthopores. Mesopore-
like spaces are present in such sections, but these are usually young
zocecia. At the surface of the zoarium such spaces are practically
wanting, the zowcia being regularly polygonal and in contact on all
sides. The semidiaphragms, which in vertical sections are noted
to frequently curve slightly downward, are seen in tangential sections
where they appear as a more or less curved line crossing the zocwecium.

294 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The raassive zoarium, extremely thin-walled polygonal zoccia,
absence of acanthopores, few mesopores, crenulated zocecial tube and
numerous semidiaphragms of H. subsphervcum should suffice to dis-
tinguish it from associated as well as other massive bryozoans.
Externally Monotrypa jewensis is quite similar, but the vertical frac-
ture of H. subsphericum showing semidiaphragms will distinguish
them. A globose Hemiphragma in the lowest Trenton strata of the
United States is closely related to the form under discussion, but as it
remains undescribed, comparisons are unnecessary.

Occurrence.—Abundant in the Wesenberg limestone (EK) at Wesen-
berg, Esthonia, and vicinity.

Cotypes.—Cat. No. 57423, U.S.N.M.

Specimens and thin sections in the collection of the British Museum.

HEMIPHRAGMA ROTUNDATUM, new species.

Text fig. 180.

The type-specimen of this species is a rounded, subpyriform mass,
about 20 mm. long and 14 mm. in diameter, with a smooth, cellulif-
erous surface and inconspicuous macule. The zocecial apertures
are direct, angular, thin-walled, and exhibit sharp acanthopores of
medium size at many of their junction angles. Five to six occur
in2mm. The mesopores are angular, usually small and few, seldom

Fic. 180.—HEMIPHRAGMA ROTUNDATUM. 4d, SIDE VIEW OF THE TYPE-SPECIMEN, NATURAL SIZE; 0, TAN=
GENTIAL SECTION OF THE TYPE, X20; c, A VERTICAL SECTION, X20, ILLUSTRATING THE TABULATION OF
BOTH ZOGCIA AND MESOPORES; d, A FEW ZOG@CIA, X35. ORTHOCERAS LIMESTONE (B3), ISLAND OF
RoGo, EsTHONIA.

numerous enough to isolate the zocecia. Under a hand lens maculz
composed of larger zocecia and more numerous mesopores may be
observed at regular intervals. The zocecial apertures, when likewise
magnified, often exhibit the semidiaphragms at or near the surface
as a partition extending half way across the opening.

Vertical sections exhibit two features in particular. First the
zocecial tubes are occupied by semidiaphragms, as noted above,
these appearing in thin sections as incomplete partitions projecting

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 295

from either side of the tube half way across the cavity. Occasionally
a complete diaphragm seems to be present, but this is merely an
incomplete one cut parallel to its edge instead of across it. These
partitions are placed at a rather uniform distance of half a tube diam-
eter apart in the more crowded or mature zone. The second notice-
able feature of vertical sections is the occurrence of well-marked
mesopores crossed by normal, entire partitions at intervals of their
own diameter. These mesopores are regularly beaded tubes as long
as their diameter is less than that of the ordinary zocecia, but as soon
as the size of the latter is reached, their walls become straight and
semidiaphragms are introduced, showing that the mesopores have
been replaced by zocecia. .

In vertical sections the present species is quite similar to Hemi-
phragma pygmxum from the Chasmops limestone of the island of
Oeland. Tangential sections show that the latter has considerably
smaller zocecia, thicker walls, and much stronger acanthopores.
Again, the zoaritum of H. pygmxum, although subglobular in shape,
is of small, pedunculate masses. Another massive species in the
Baltic Ordovician is the H. subsphericum from the Wesenberg forma-
tion, but its large, thin-walled, angular zocecia, with few mesopores
are quite distinct from those of both the above forms, although again
the vertical section is somewhat similar.

Occurrence.—Rare in the Orthoceras limestone (B3), island of
Rogo, near Baltischport, Esthonia. The species also occurrs in the
Kchinospherites limestone (C1) at Reval. Specimens are also known
from the Kuckers shale (C2) at Reval, and from Baron Toll’s estate,
Esthonia.

Holotype.—Cat. No. 57424, U.S.N.M.

Thin sections of a specimen from the Orthoceras limestone, island
of Rogo, are in the collections of the British Museum.

HEMIPHRAGMA MACULATUM, new species.

Text fig. 181.

Zoarium of small, slender, cylindrical branches 2.5 mm. in diam-
eter on an average. Surface without elevations but conspicuously
marked by large, distinct macule 2.5 mm. apart, measuring from
center to center. These macule, which are composed entirely of
small mesopores, are frequently several millimeters in diameter, and
as they are slightly depressed and are arranged alternately the
branches are irregularly constricted along a spirally ascending line.
Zocecia polygonal, six in 2 mm., with rather thick walls. Mesopores
angular, numerous but exceptionally small. Acanthopores absent.

Figure 181 6 and ¢ shows the usual view in tangential sections.
The unusually small mesopores, the thickness of the walls in both
kinds of cells, and the absence of acanthopores, are most character-

296 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

istic. In vertical sections the walls in the immature zone are seen
to be thin and crenulated. An occasional incomplete diaphragm
occurs here as well as in the mature zone, although they are scarce
in the latter region. The mesopores when not obscured by the dense
tissue of the interzocecial spaces are distinctly beaded and have dia-
phragms about their own diameter apart.

Externally the narrow, cylindrical branches, polygonal thick-

Fig. 181.—HEMIPHRAGMA MACULATUM. @, A FRAGMENT, X2, EXHIBITING PORTIONS OF TWO MACUL;
b, TANGENTIAL SECTION, X20, THROUGH THE INTERMACULAR ZOG@CIA; Cc, SEVERAL ZOGCIA OF THE SAME
SECTION, X40; d, VERTICAL SECTION, X20, THROUGH THE ENTIRE WIDTH OF A BRANCH. KUCKERS SHALE
(C2), REVAL, ESTHONIA.

walled zocecia with numerous very minute angular mesopores, will
readily serve for the identification of H. maculatum. 'The incom-
plete diaphragm, crenulated walls, and small mesopores are especially
characteristic of thin sections.

Occurrence.—Not uncommon in the Kuckers shale (C2) at Reval,
and Baron Toll’s estate, Esthonia.

Holotype.—Cat. No. 57428, U.S.N.M.

British Museum, thin section of the type-specimen.

HEMIPHRAGMA BATHERI, new species.

Text fig. 182.

The zoarium of this well-marked species is of small, frequently
branching, cylindrical stems averaging 2 mm. in diameter. The sur-
face is smooth and presents no conspicuous macule, as in the preced-
ing species, although clusters of larger zocecia and more numerous
mesopores are present as usual. Zocecia polygonal, thick-walled, with
solid interzocecial spaces; five to six zoceciain 2mm. Acanthopores
small, sometimes numerous at the surface where they occur along the
crest of the zocecial wall. Mesopores few, averaging about one to a
zocecium, usually filled by the dense tissue forming the solid interzoc-
cial spaces. Through this tissue the outlines of the mesopores are
visible in thin sections.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 297

The internal structure is simple, although very characteristic for
the genus. In tangential sections the angular zocecia and mesopores
with their thick walls bearing rather small acanthopores are to be
noted. Vertical sections show thick, well developed, incomplete dia-
phragms in the mature region, with thin, flexuous walls and no dia-
phragms in the immature zone.

Excepting Hemiphragma maculatum, this species differs from all
others of the genus in its very slender, ramose zoarium. ‘The internal
structure is somewhat similar to that in H. panderi, but the latter has
a stouter zoarium with smaller zocecia, fewer mesopores, and more
numerous acanthopores. The specific name is in honor of Dr. F. A.
Bather, who collected the type-specimens.

Fic. 182. HEMIPHRAGMA BATHERI. @ AND 0, TWO FRAGMENTS, NATURAL SIZE; Cc, A TANGENTIAL SECTION,
X20, SHOWING THE CHARACTERISTIC, THICK-WALLED, POLYGONAL ZOCGCIA; d, VERTICAL SECTION OF A
BRANCH, X20, EXHIBITING CHARACTERISTIC TABULATION. CHASMOPS LIMESTONE, SOUTH OF BODAHAMN,
ISLAND OF OELAND.

Occurrence.—Not uncommon in the Chasmops limestone, south of
Boédahamn, island of Oeland.

The figured types and sections are in the collections of the British
Museum.

Genus ANAPHRAGMA Ulrich and Bassler.
Anaphragma UuricH and BassteR, Smiths. Misc. Coll., vol. 47, 1904, p. 49.

This genus was established for a species agreeing in all respects with
Batostoma Ulrich, save that the zocecial tubes and mesopores were
practically free of diaphragms, and that the walls in the immature
region were strongly crinkled. Up to this time but a single species
was known, Anaphragma mirabile from the Fernvale limestone of the
Richmond group in Illinois and Wisconsin.

Genotype.—Anaphragma mirabile Ulrich and Bassler. Early
Silurian (Richmond) of Illinois, Wisconsin, and Esthonia.

298 BULLETIN 7, UNITED STATES NATIONAL MUSEUM.

ANAPHRAGMA MIRABILE Ulrich and Bassler.
Text fig. 183.

Anaphragma mirabile UnRicH and BassLeR, Smiths. Misc. Coll., vol. 47, 1904, p.

49, pl. 13, figs. 9-11.
The discovery of this unusual type in the Russian deposits is a most
interesting example of the wide geographic range of the Bryozoa, and
of their consequent value in detailed correlation. After a most critical

Fic. 183.—ANAPHRAGMA MIRABILE. @, VIEW OF AN IRREGULARLY GROWING BRANCH, NATURAL SIZE;
b, TANGENTIAL SECTION, X20; c, SEVERAL ZO@CIA OF ANOTHER PART OF THIS SECTION, X20, SHOWING
NUMEROUS ACANTHOPORES; d, A VERTICAL SECTION, X9, THROUGH THE ENTIRE WIDTH OF THE BRANCH;
€, PORTION OF THE SAME SECTION, X20, SHOWING THE STRUCTURE IN MORE DETAIL. LYCKHOLM LIME-
STONE (F1), HOHENHOLM, ISLAND OF Dago.

comparison of numerous thin sections of both American and Russian
specimens of the species, I am unable to point out any differences
between them. The figured vertical sections of the type showed no
diaphragms in the zoecial tubes, but a restudy of the species in con-
nection with the present work brought out the fact that an occasional
diaphragm may occur, its place usually being at the bend from the
immature to the mature region. The most marked example of such
an occurrence is shown in the vertical sections, figures 183 d and ¢.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 299

Other sections, even from the same specimen, show ho diaphragms at
all. This has required a slight emendation in the original diagnosis
of the genus.

The zoarium of Anaphragma mirabile is of smooth, strong, sub-
cylindrical branches, 8 to 10 or more millimeters in diameter, divid-
ing rather frequently. Macule not a conspicuous feature; distin-
guished only by the size of their zocecia, which are somewhat larger
than the average. Zocecial apertures angular to subangular, with
rather thick walls, five to six zoccia in 2 mm.; mesopores small and
comparatively few in number; acanthopores small and seldom well
shown at the surface, although when observed they show the usual
apical perforation.

In vertical sections the striking feature is the almost complete
absence of diaphragms in both the zocecia and mesopores. In the
axial region the walls are thin and wavy, the crenulations being long
and not so frequent as in species of Calloporina, a somewhat similar
genus of the Halloporide. With the inception of the mature region,
the walls become greatly thickened and considerable laminated tissue
is developed upon the inner sides. Tangential sections show the
zocecial walls to be of considerable thickness and to have the charac-
teristic structure of Batostoma. The acanthopores are seen to be
small, few in number, and situated at the junction angles.

The rather large angular zocecia, thick walls, and few mesopores,
and, more satisfactorily, the crenulated tubes with their practical
absence of diaphragms, distinguish this species from otherwise
similar associated forms.

In the thin sections shown in figure 183 6 and c, the acanthopores
and the dark line separating adjoining zocecia are especially well
developed.

Occurrence.—The species is a characteristic fossil of the Fernvale
limestone division of the Richmond group in the Mississippi Valley,
the type-locality being Wilmington, Illinois. The Russian examples
of the species were found in the upper part of the Lyckholm limestone
(F1) at Kertel, and at Hohenholm on the island of Dago.

Plesiotype—Cat. No. 57385, U.S.N.M.

Represented in the collections of the British Museum by American
specimens.

ANAPHRAGMA MIRABILE COGNATA, new variety.

Text fig. 184.

Zoarium ramose with branches subcylindrical, frequently dividing,
and 6 to 8 or more millimeters in diameter; macule not a conspic-
uous feature of the surface, which is smooth. Zoccial apertures
polygonal with rather thick walls. Five zoeciain2mm. Mesopores
few and small, acanthopores small and sometimes numerous but not
conspicuous at the surface.

92602°—Bull. 77—11——21

300 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The most marked character seen in vertical sections or in longi-
tudinal fractures is the great crinkling of the zocecial walls in the
immature region and the almost entire absence of diaphragms in
this and the mature regions. In the latter the zocecial walls thicken
greatly, the crenulation is less marked or disappears entirely, and
acanthopores are developed. Mesopores, which occur only in the
mature region, are distinguished with difficulty on account of their
similarity to the ordinary zocecia. The thick walls, small acantho-

epee ane to
EER NT AN CRS
me ESE
SS

Fig. 184 ANAPHRAGMA MIRABILE COGNATA. @, VIEW OF FRAGMENT, NATURAL SIZE; b, TANGENTIAL
SECTION, X20, WITH WALL STRUCTURE PLAINLY MARKED; ¢ AND d, VERTICAL SECTION, X8, AND A POR-
TION, X20. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

pores, and the black line separating adjoining zoccia, are well shown
in tangential sections.

The present species differs so much from associated ramose bryo-
zoans in the practical absence of diaphragms and the strong, crenu-
lated walls, that comparisons are unnecessary. Critically compared
with Anaphragma mirabile, however, it is found to agree in growth,
thickness of zocecial walls, and in most of the internal characters,
differing only in that the walls are more crenulated and that the
zocecia are a trifle smaller. These differences are possibly of specific

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 801

importance in so simple a form, but the Middle Ordovician form is
undoubtedly the progenitor of the early Silurian genotype, and the
purposes of classification may, perhaps, be best furthered by con-
sidering it as only a variety.

Occurrence.—Found in the Wassalem beds (D3) at Uxnorm and
Gut Sack, and in the Wesenberg limestone (E) at Wesenberg,
Ksthonia.

Holotype.—Cat. No. 57387, U.S.N.M.

Fragment and thin sections of the type-specimen in the collections
of the British Museum.

Genus DITTOPORA Dybowski.

Ditiopora DyBowsx1, Die Chaetetiden der Ostbalt. Silur-Formation, 1877, p. 84.—
NicHotson, Genus Monticulipora, 1881, p. 234——Rormer, Lethexa geog-
nostica, pt. 1, Leth. Pal., 1883, p. 479.

' Trematopora DyBowsxi, Die Chaetetiden der Ostbalt. Silur-Formation, 1877,

p. 69.

This generic name was proposed for certain monticuliporoids in
which, according to Dybowski, the corallites were of two kinds, one
being cylindrical and separated by a reticulate coenenchyma, and
the other consisting of prismatic tubes in close contact. These two
kinds of corallites, according to the same author, may be arranged
in alternating rows or may be confined to particular parts of the
colony. Wandréhrchen (acanthopores) and tabule are present.
In the genotype, D. claveformis Dybowski, in which the colony is
club-shaped, the prismatic corallites are restricted to the basal por-
tion, while the cylindrical kind of corallites occur in the upper
portion of the stem. In a second species, D. annulata (Kichwald),
the two kinds of corallites are arranged in alternating, transversely
elongated zones.

Both of these species are well represented in the collections before
me, and from a study of them, I must conclude that Dybowski’s
generic characters are valueless—indeed the same features are found
in many diverse genera. The cylindrical corallites separated by a
reticulate coenenchyma are simply the ordinary zoccia with inter-
vening, closely tabulated mesopores. The prismatic tubes in close
contact are thick-walled mesopores which, in D. claveformis are
extremely abundant at the base of the zoarium, and in D. annulata
form the ring-like macule. Thin sections of the two species men-
tioned, and of the very abundant Trematopora colliculata Kichwald,
indicate that these European forms constitute a natural group closely
related on one hand to TYrematopora and on the other to Hemi-
phragma. It is, therefore, deemed advisable to retain the name
Dittopora for this group of species, with the following amended
definition.

302 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Zoarium ramose, growing from an expanded base into more or less
branching stems. Zocecial structure as in the Trematoporide, quite
similar to Hemiphragma but differing in having the incomplete dia-
phragms practically limited to the bend from the immature to the
mature zone. Elsewhere the diaphragms aré complete. Mesopores
numerous, moniliform, with tabule at their constricted portions.
Acanthopores developed in two fairly well marked sets, the first
consisting of a pair of large acanthopores situated one on each side
of a zocecium, and the second of numerous smaller ones distributed
indiscriminately along the walls of both zocecia and mesopores.

The diagnostic generic distinctions of Dittopora, in addition to the
general family characters, are believed to be, first the restriction of
incomplete diaphragms to the earliest part of the mature zone, and,
second, the occurrence of two distinct sets of acanthopores. The
internal structure of the genotype, as shown in figure 185, is identical
with that of D. annulata, and is equally well developed in Eichwald’s
Trematopora colliculata, which Dybowski considered a typical species
of Trematopora.

Genotype—Duttopora claveformis Dybowski. Middle Ordovician
of Esthonia.

DITTOPORA CLAVZEFORMIS Dybowski.

Plate 3, figs. 7-7 6; plate 11, figs. 18-24; text fig. 185.

Dittopora clavxeformis DyBowskx1, Die Chaetetiden Ostbaltischen Silur-Forma-
tion, 1877, p. 85, pl. 2, figs. 7-7b.—Nicnotson, The Genus Monticulipora,
1881, p. 235, fig. 50.

The shape of the zoarium in this interesting species is so distinct
from most other Ordovician bryozoans that the species is easily iden-
tified. Dybowski has given a good description of both the external
and internal features, the latter, however, based upon his interpre-
tation of the generic characters. As shown in Dybowski’s figures on
plate 8, the zoarium is of small, club-shaped stems, often with a
slightly expanded base. Growth commences upon a foreign object,
such as the brachiopod shell (pl. 11, fig. 24), and continues until a
colony 10 to 20 mm. high results. With age the basal part of the
zoarium becomes covered with elongate, thick-walled mesopores
similar to those found in the basal portions of many other bryozoans.
Surface of zoarium usually smooth, but occasionally the macule are
so strongly developed that they encircle the branch, and being
slightly depressed, give the annulated effect seen in figure 22 of
plate 11. Zoarial growth usually stops with the formation of a single
club-shaped mass, but occasionally a second similarly shaped zoarium
arises from the upper portion of the first. Rarely the initial zoarium
bifurcates (see pl. 11, fig. 23).

Zocecia small, elongate-oval in young specimens but angular,
thick-walled in the more mature condition. Mesopores numerous,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 3803

closed at the surface. Acanthopores in the usual two sets, but in old
examples there is little difference in their respective size and they
are so numerous that a granulose appearance is imparted to the
zoarial surface. An ordinary zoccium is 0.33 mm. in diameter
with five in 2 mm.

The important features of thin sections have been indicated in the
remarks on the genus. A tangential section of a young example is
shown in figure 185 a, mainly to exhibit the two sets of acanthopores,
the larger set in this case being located about the zocecia in pairs,
and the smaller in the walls of the mesopores forming a macula.
Tangential sections of an older example show numerous acantho-
pores of more equal.size.

Vertical sections show the usual close tabulation in the mesopores,

Fig. 185.—DITTOPORA CLAVEFORMIS. @, TANGENTIAL SECTION, X20, OF A YOUNG EXAMPLE SHOWING
TWO SETS OF ACANTHOPORES AND SHAPE OF ZOGCIA DISTINCTLY; 0, VERTICAL SECTION OF THE SAME SPECI-
MEN, X20, ILLUSTRATING DISTRIBUTION OF SEMIDIAPHRAGMS. GLAUCONITE LIMESTONE (B2), REVAL,
ESTHONIA.

but the zocecial tubes have well-marked semidiaphragms in both the
immature and mature regions. The outer region of the mesopores
is usually filled with a dense tissue through which the acanthopores
penetrate.

The only bryozoan with a similar method of growth is the Stigma-
tella clariformis (Ulrich) from the Wassalem beds, but its zocecial
structure is so different that comparisons are unnecessary. The
associated Dittopora annulata has a similar internal structure, but its
growth is strictly ramose.

Occurrence.—Common in the Glauconite limestone (B2) at Pulkowa,
Wassilkowa, Tswos, and other localities in the government of St.
Petersburg; in the same formation at Reval and at Strietburg, in
Esthonia.

Plesiotypes.—Cat. Nos. 57390 to 57396, U.S.N.M.

British Museum, specimens from Reval, Esthonia.

304 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

_DITTOPORA ANNULATA (Eichwald).
Plate 3, fig. 5; plate 11, figs. 16, 17; text figs. 186, 187.
Chetetes annulatus Erchwaup, Lethza Rossica, vol. 1, sect. 1, 1860, p. 480,
pl. 28, figs. 2a-2c, 3a-3d.
Dittoporaannulata DyBowsk1, Die Chaetetiden derOstbaltischen Silur-Formation,
1877, p. 86, pl. 2, fig. 5.—Nicnotson, The Genus Monticulipora, 1881, p. 234,
fig. 49.

Zoarium of small, ramose, frequently dividing branches 3 to 6 mm.
in diameter. Surface finely spinulose on account of the numerous
small acanthopores; macule of thick-walled mesopores usually
closed at the surface, and encircling the branch, giving the character-
istic annulated appearance. In the early portion of the mature
region the usual pair of larger acanthopores, one on each side of a

Fig. 186.—DITTOPORA ANNULATA. COPY OF EICHWALD’S ILLUSTRATIONS OF CHATETES ANNULATUS. @,
FRAGMENT OF A NORMAL MATURE ZOARIUM, NATURAL SIZE; 6, SMALL PORTION OF THE SAME MAGNIFIED
TO SHOW THE ARRANGEMENT OF THE RING-LIKE MACULH AND THE DISTRIBUTION OF ZO@CIA AND MESO-
PORES; C, END VIEW OF A FRAGMENT ENLARGED; d, VIEW OF CELLS IN SECTION; € AND /, FRAGMENT OF
AN OLD EXAMPLE AND A PORTION ENLARGED. HERE THE ZOG@CIA ARE ALMOST ENTIRELY OBLITERATED
BY THE EXTENSIVE DEVELOPMENT OF MESOPORE-LIKE CELLS: g, END VIEW OF BRANCH, MAGNIFIED.
*CALCAIRE A ORTHOCERATITES,’?’ PULKOWA AND POPOWKA, GOVERNMENT OF ST. PETERSBURG.

zocecium, is present, but numerous smaller acanthopores develop in
the later portions of the same zone and become so nearly equal in
size that the distinction between the two sets is lost. The tangential
sections shown in figure 187 a and 6 are through this older portion
of the mature region. Dybowski’s figure (pl. 3, fig. 5) represents
the larger set more distinctly, and also shows the hour-glass shape
imparted to the zocecia by the indentations of the walls whenever a
pair is well developed. Vertical sections show essentially the same
structure as in D. claveformis. Semidiaphragms are fewer in D.
annulata and occur mainly in the bend to the mature zone.

While it is recognized that D. claveformis and D. annulata are
closely related, the ramose habit of growth of the latter is the most
obvious difference. The ring-like macule are not of specific impor-
tance, because they are equally well developed in all of the other
species of Dittopora. .

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 305

Occurrence.—A common fossil in the Glauconite limestone (B2)
at Popowka, Tswos, Wassilkowa, Oberchow, Grenaja Sheldacha, and
other localities in the government of St. Petersburg. Less abundant
in the Orthoceras limestone (B3) on the island of Rogo, near Bal-

Fig. 187.—DITTOPORA ANNULATA. d@, TANGENTIAL SECTION OF A MATURE EXAMPLE, X20, PASSING THROUGH
THE OUTER DEPOSIT OF INTERZOGCIAL TISSUE IN WHICH THE MESOPORES ARE BARELY VISIBLE; b, AN-
OTHER TANGENTIAL SECTION, X20, CUTTING A MACULA AT A LOWER LEVEL AND EXHIBITING THE MESO-
PORES; C, VERTICAL SECTION, X20, OF A YOUNG EXAMPLE, SHOWING THE OCCURRENCE OF SEMIDIA-
PHRAGMS IN THE BEND FROM THE IMMATURE TO THE MATURE REGION; d, SIMILAR SECTION OF AN OLDER
SPECIMEN, X20, WITH THE MESOPORES WELL DEVELOPED AND THEIR OUTER PORTIONS FILLED BY TISSUE.
GLAUCONITE LIMESTONE (B2), WASSILKOWA, GOVERNMENT OF ST. PETERSBURG.

tischport, Esthonia. Rare in the Echinospherites limestone (C1), 4
miles east of Reval.

Plesiotypes.—Cat. Nos. 57397 to 57402, U.S.N.M.

British Museum, specimens and thin sections from the Glauconite
limestone, Tswos.

306 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

DITTOPORA COLLICULATA (Eichwald).
Plate 3, figs. 14c, 6; plate 11, figs. 7-15; text figs. 188-190.

Trematopora colliculata Erchwatp, Bull. Soc. Nat. Moscou, No. 1, 1856, p. 96.—
Scumipt, Archiv. fur d. Nat. Liv-, Ehst- und Kurlands, vol. 2, ser. 1, 1858,
p. 228.—E1cHwa.pD, Letheea Rossica, vol. 1, sect. 1, 1860, p. 494, pl. 27, figs.
14a-c.—DyxsowsxkI, Die Chaetetiden der Ostbaltischen Silur-Formation,
1877, p. 72, pl. 2, figs. 4-4c.—Nicnoitson, The Genus Monticulipora, 1881,
p. 233, fig. 48.

Trematopora cingulata DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 78, pl. 2, figs. 1, 10.

Trematopora cingulata var. nodosa DyBowsx1, Die Chaetetiden der Ostbaltischen
Silur-Formation, 1877, p. 80, pl. 2, fig. la.

Trematopora variabilis DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 81, pl. 2, figs. 2, 2a.

Trematopora variabilis var. complanata DyBowsx1, Die Chaetetiden der Ost-
baltischen Silur-Formation, 1877, p. 83, pl. 2, figs. 3, 3a.

Trematopora pustulifera DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 80, pl. 2, fig. 6.

Dybowski has given a lengthy, detailed description of Eichwald’s
Trematopora colliculata, and more or less extended descriptions of
the species and varieties listed above assynonyms. On account of the
marked external peculiarities, elongate-oval zocecia with closed
interzocecial spaces, Eichwald’s illustrations (fig. 188) are sufficient
for the identification of his species; moreover, Dybowski has figured

the internal structure

ee fairly well (see pl. 3,
figs. 4-4 6). I have
examined over 400
specimens with this
same internal struc-
ture. Of these a small
‘percentage have their
macule raised into
rounded monticules, as
figured by Hichwald,
a large number have
Fig. 188.—DITTOPORA COLLICULATA. EICHWALD’S FIGURES OF their monticules trans-

TREMATOPORA COLLICULATA. @ AND b, FRAGMENT OF ZOARIUM, versely elon g at ed,

NATURAL SIZE, AND SURFACE OF SAME, ENLARGED. ‘‘CALCAIRE A : °
ORTHOCERATITES,’’? REVAL, ESTHONIA. while, finally, in the

largest number of
specimens the macule are not raised at all, but are so elongated
that they form an encircling ring about the zoarial branch. Such
variation is not unusual in species of Batostoma and other genera
of the Trematoporide, although it is especially well developed in the
present form.
Numerous thin sections of these several forms have been prepared
and the internal structure in each found to be identical. Moreover,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 307

there are all degrees of gradation in the extent and elevation of the
macule, so that little question can be raised as to the specific identity
of the forms here considered as synonyms. Comparing Dybowski’s
figures, we find that in Trematopora cingulata (pl. 3, figs. 1, 16) the
maculez do not rise above the general surface and are so elongated
transversely as to form encircling rings. T. cingulata var. nodosa
(pl. 3, fig. 1a) differs only in having these ring-like macule slightly
elevated. In T. variabilis (pl. 3, figs. 2, 2a) the macule, although
transversely elongate, are arranged somewhat irregularly and the
acanthopores are more numerous. JT. variabilis var. complanata (pl.
3, figs. 3, 3a) has the same zoeecial structure and differs only in the
very irregularly shaped monticules. Dybowski’s tangential sections
(pl. 3, figs. 1b, 2a, 3a, 4a, and 4c) are sufficient in themselves to show
the identity of his various species, but the only illustration of T.
pustulifera (pl. 3, fig. 6) shows apparently a somewhat different
internal structure. Examination of Dybowski’s type-specimen,

Fig. 189.—DITTOPORA COLLICULATA. @, TANGENTIAL SECTION OF A YOUNG EXAMPLE, X20, SHOWING THE
CHARACTERISTIC SHAPE OF ZOG@CIA AND THE LARGER SET OF ACANTHOPORES; 6b, VERTICAL SECTION OF
THE SAME SPECIMEN, X20. WASSALEM BEDS (D3), UXNORM, ESTHONIA.

kindly loaned by Doctor Mikhailowski, proves T. pustulifera to be
only a form of this same abundant Ditiopora, with numerous well-
developed acanthopores and a zoarium without conspicuous macule.
To show this identity, a figure of a tangential section prepared from
the type is introduced (fig. 190 6). Considering the numerous new
species of Trepostomata in the Russian Ordovician, it is odd that this
particular form should have received so many names. ‘The following
description is believed to cover the essential characters of the species.

Zoarium growing from a rounded or somewhat pointed base into
straight, cylindrical, rather infrequently dividing branches, varying
from 3 mm. to 10 mm. or more in diameter. Surface with more or
less elongated solid maculze composed of closed mesopores bordered
by a row of zoccia slightly larger than the rest. Macule often
transversely elongated to such an extent that frequently several
coalesce and form a continuous uncelluliferous band about the branch.

308 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

The maculz may be on a plane with the surface or may rise as rounded
or elongated monticules. These various developments of the macule
are shown in Dybowski’s figures and also on plate 11. °

Zocecia oval with a well-marked peristome, four in 2 mm. measuring
lengthwise, and shaped like the figure 8 because of a constriction in
the mid-length caused by the indentation of the walls by a pair of
large acanthopores (fig. 189 a). In some forms this regular arrange-
ment is somewhat obscured by the introduction of several additional
equally large acanthopores less regularly placed. These large acan-
thopores are ring-form with a conspicuous central open space or
lumen, and are in marked contrast with the second set of acan-
thopores, which consists of numerous smaller, more granular struc-
ures irregularly placed on the mesopore walls. The arrangement
and relative size of these two sets are illustrated in figure 189 a.

OF THE MESOPORES VISIBLE. THE LARGE AND SMALL SET OF ACANTHOPORES ARE CLEARLY DEVELOPED;

b, ANOTHER TANGENTIAL SECTION, X20, WITH THE MESOPORES AND SMALL ACANTHOPORES OBLITERATED
BY THE INTERZOGCIAL TISSUE. THIS THIN SECTION WAS PREPARED FROM A SPECIMEN IDENTIFIED BY
DYBOWSKI AS TREMATOPORA PUSTULIFERA; ¢, VERTICAL SECTION, X20, SHOWING THE OCCURRENCE OF
SEMIDIAPHRAGMS ONLY IN THE BEND TO THE MATURE ZONE. WASSALEM BEDS (D3). UXNORM AND
WASSALEM, ESTHONIA.

Mesopores closed at the surface, and so numerous as to isolate the
ZoceCcia.

The important features shown in tangential sections are the oval,
frequently constricted zocecia with thick, ring-like walls, the large
acanthopores with well defined central space, and the smaller, more
granular acanthopores irregularly placed in the inter-zocecial spaces.
Such sections prepared from near the surface of well developed speci-
mens show only a dense tissue penetrated by the smaller acanthopores
in the interzoccial spaces (fig. 190 b), but in deeper sections (fig. 190 a),
the outlines of the mesopores are visible.

On account of the thickness of the mature zone, it is difficult to
prepare vertical sections showing the full length of the zocecial tubes.
This difficulty was experienced by Dybowski, as is evidenced by his
figured vertical section (pl. 3, fig. 4b) of the type form of the spe-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 3809

cies. In order to show all of the characters seen in such sections, I
have introduced figures of sections prepared from a young zoarium
and a portion of a section of an old example (figs. 189 b and 190 ce).
The arrangement of diaphragms is essentially the same in both.
In the immature zone the diaphragms are complete and are at dis-
tances of two or more tube diameters from each other. In the bend
from the immature to the mature zone, a few semidiaphragms are
developed, while in the mature zone proper a few scattered complete
diaphragms may be seen. The tabulation and wall structures of the
mesopores is as usual in members of this family. In the earlier stages
the walls are moniliform and diaphragms are inserted regularly;
later the diaphragms become more numerous and in addition are
thickened and appear irregularly placed because of the deposition of
layers of tissue upon them. In old examples this tissue is so abun-
dant at the surface that the mterzoccial spaces are closed entirely.
The closely tabulated mesopores with this deposit of tissue gave rise
to Dybowski’s idea of a ‘‘coenenchyma”’ separating the corallites
or ordinary zocecia.

In its specific character Dittopora colliculata is approached by no
described species. The large, oval, constricted zocecia, conspicuous
acanthopores, closed interzocecial spaces with a zoarium of cylindrical
stems, made it easy of recognition without considering the marked
internal characters.

Occurrence.—Very abundant in the Wassalem beds (D3) at Uxnorm,
Gut Sack, and Wassalem, Hsthonia. Rare in the Wesenberg lime-
stone (EK) at Wesenberg; in the Kuckers shale (C2), Baron Toll’s
estate, and in the lowest part of the Lyckholm limestone (F1) at
Kertel and Hohenholm, island of Dago. Several specimens were
collected by Doctor Bather in the Chasmops limestone, south of
Bédahamn, island of Oeland.

Plesiotypes.—Cat. Nos. 57403 to 57409, U.S.N.M.

Specimens and thin sections from the Wassalem beds at Uxnorm,
and from the Chasmops limestone, island of Oeland, are in the collec-
ticns of the British Museum.

Genus MONOTRYPA Nicholson.

Monotrypa NicHouson, Paleozoic Tabulate Corals, 1879, p. 293; Genus Monti-
culipora, 1881, pp. 102, 168—Utricu, Journ. Cincinnati Soc. Nat. Hist.,
vol. 5, 1882, p. 153.—Hatt and Simpson, Nat. Hist. New York, Paleontology,
vol. 6, 1887, p. xiii—Uxricu, Geol. Surv. Illinois, vol. 8, 1890, p. 379; Geol.
and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 303; Zittel’s Textbook
of Paleontology (Eng. ed.), 1897, p. 275.—Simpson, Fourteenth Ann. Rep.
State Geologist of New York for the year 1894, 1897, p. 581._NicKuEs and
Basster, Bull. 173, U. 8. Geol. Surv., 1900, p. 36. _—BAsstEr, Bulll 2925 Ws:
Geol. Surv., 1906, p. 46.—HeEwnic, ‘Archiv. tur Zool., vol. 4, No. 10, 1908,
p. 46.

Ptychonema Haut and Smrson, Nat. Hist. New York, Pal., vol. 6, 1887, pp. xiv,
14.—_Srmrson, Fourteenth Ann. Rep. State Geologist of New York for the
year 1894, 1897, p. 583.

310 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In Monotrypa the simplest structure of the Trematoporide is
present. The zoarium is massive and composed of simple, thin-
walled, polygonal zocecia in contact, both mesopores and acantho-
pores being absent. Internally the wall structure is as in other
trematoporoid genera, even to the crinkling so often noted in the
family. The only species so far found in the Russian collections
seems to be closely allied to the genotype.

Genotype.—Chetetes undulatus Nicholson. Middle Ordovician of
Canada.

MONOTRYPA JEWENSIS, new species.

Text fig. 191.

Cir. Monotrypa undulata NicHotson, Paleozoic Tabulate Corals, 1879, p. 321, pl.
14, figs. 3-36, 4, 4a.

Zoarium of rounded, hemispherical, or depressed spherical masses
10 to 15 mm. in diameter and also in height. Celluliferous surface
smooth, with thin-walled, polygonal zocecial apertures, four to five in
2mm. Clusters of zoccia larger than usual present at regular inter-
vals but inconspicuous. Occasionally small, angular mesopore-like
openings are scattered among the ordinary apertures, but these rep-
resent young zocecia.

The important features of vertical sections are the crenulations of
the zoccial walls and the practical absence of diaphragms both in
the immature and mature zones. Occasionally a single diaphragm
is inserted in the outer portion of the mature zone as represented in
figure 191 c. Tangential sections show the extreme simplicity of
structure of the thin-walled, angular zoecia.

The massive habit of growth, thin-walled polygonal zoecia, crenu-
lated walls, and practical absence of diaphragms are characters which
will distinguish this species from all associated forms and cause it to
be recognized without difficulty. A vertical fracture is of course
necessary to determine the more important characters.

Upon comparison with American forms, Monotrypa jewensis is
found to be closely related to the type of the genus, WM. undulata,
from the lower Trenton strata of Canada. The latter is not as well
known as it should be, but, judging from Nicholson’s description
and figures, M. undulata has slightly smaller zocecia and more abun-
dant diaphragms.

Occurrence—Not uncommon in the Jewe limestone (D1), Baron
Toll’s estate, and in the Kegel limestone (D2), at Kegel, Esthonia.

Holotype.—Cat. No. 57410, U.S.N.M.

British Museum, specimen and thin sections from the Jewe lime-
stone, Baron Toll’s estate.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 311

Fig. 191.—MOoONOTRYPA JEWENSIS. @, PROFILE VIEW OF A SMALL ZOARIUM, NATURAL SIZE; 6, SURFACE OF
THE SAME SPECIMEN, X10; c, VERTICAL SECTION, X8, ILLUSTRATING THE CRINKLED WALLS AND FEW DIA-
PHRAGMS; d, PORTION OF THE SAME SECTION, X20; €, TANGENTIAL SECTION, X20, CUTTING A MACULA;
f, ANOTHER TANGENTIAL SECTION, X20, WITH NUMEROUS YOUNG ZOG@CIA RESEMBLING MESOPORES.
JEWE LIMESTONE (D1), BARON TOLL’s ESTATE, ESTHONIA.

312 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Genus DIPLOTRYPA Nicholson.

Diplotrypa Nicnouson, Pal. Tabulate Corals, 1879, p. 292; Genus Monticulipora,
1881, pp. 101, 155.—Uxricn, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882,
p. 153; Geol. Surv. Illinois, vol. 8, 1890, pp. 378, 457; Geol. and Nat. Hist.
Surv. Minnesota, vol. 3, pt. 1, 1893, p. 285; Zittel’s Textbook of Paleontology
(Eng. ed.), 1896, p. 275.—Nick.eEs and Basser, Bull.173, U.S. Geol. Surv.,
1900, p. 36.—Bass ter, Bull. 292, U. 8. Geol. Surv., 1906, p. 47.

Callopora (part) DyBowsxr (not Hall), Die Chaetetiden d. Ostbaltischen Silur-
Formation, 1877, p. 106.

This division of the Trepostomata was instituted by Nicholson as
a subgenus under Monticulipora, with Pander’s Favosites petropoli-
tanus as the type. Just which particular species of the many hemi-
spheric bryozoans Pander had in mind is impossible to tell without
an examination of his type-specimen; indeed, it is not unlikely that
this author himself confused several species. Subsequently, other
writers described and figured presumably the same species, but in
almost every case their diagnoses and illustrations are insufficient
for the recognition of the species. The result of this frequently
imperfect work was that many species in Europe as well as in America
have been identified as Favosites or Chetetes petropolitanus, based
merely upon method of growth. Indeed, there has been no name
so frequently cited where it is very probable that almost every
citation refers to a different form.

In his Paleozoic Tabulate Corals, Nicholson described and illus-
trated the internal characters of hemispheric specimens from the
Chasmops limestone of Ostrogothia, Sweden, basing his new sub-
genus Diplotrypa upon these examples which he identified as Favo-
sites petropolitanus Pander. Two years previously Dybowski had
resurrected Eichwald’s imperfectly defined genus Dianulites, and had
adequately described and illustrated certain Russian hemispheric
bryozoans as Dianulites petropolitanus (Pander). The internal struc-
ture of these two forms, identified as the same species, is totally
different, and the identification of Pander’s species is still uncertain.
It happens, however, that the form identified by Nicholson as Pan-
der’s species is very abundant throughout the Russian Middle Ordo-
vician, and likewise that Dybowski’s Dianulites petropolitanus (Pan-*
der) is associated with the Swedish Diplotrypa petropolitana in the
latter country; moreover, they are generically distinct. The way is
thus open to clear this complicated mixture of species and genera by
recognizing Nicholson’s identification as Dvzplotrypa petropolitana
Nicholson, and regarding Dybowski’s conception of the species as a
valid form of Dianulites.

The genus Diplotrypa comprises species with massive or discoid
free zoaria, composed of comparatively large zocecial tubes with thin,
prismatic walls. Mesopores are always present, although they vary
in number and size. The diaphragms are horizontal and more or.
less abundant in both zoccia and mesopores; acanthopores wanting.

tc eT eT

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 313

In other words, the genus is like Monotrypa save that mesopores are
present.

Genotype.—Diplotrypa petropolitana Nicholson. Middle Ordovician
of Baltic Russia and Sweden.

DIPLOTRYPA PETROPOLITANA (Nicholson).
Text figs. 192-195.

Monticulipora (Diploirypa) petropolitana Nicnouson, Pal. Tab. Corals, 1879, p.
313, pl. 18, figs. 3-3 c; The Genus Monticulipora, 1881, p. 156, text fig. 30.
The following may also be included, at least in part, in the present
species:

_Millepora hemispherica (part) Eichwatp, Inter ingrica et de trilob. observat.,
1825, p. 21.

Favosites petropolitanus PANDER, Beitr. zur Geogn. d. russ. Reiches., 1830, p. 105,
pl. 1, figs. 7-11.

Fic. 192.—DIPLOTRYPA PETROPOLITANA. NICHOLSON’S ILLUSTRATIONS OF MONTICULIPORA (DIPLOTRYPA)
PETROPOLITANA, INTRODUCED FOR COMPARISON. @, PROFILE VIEW OF AN AVERAGE SPECIMEN,
NATURAL SIZE; 6, BASAL VIEW OF SAME SHOWING WRINKLED EPITHECA; C, TANGENTIAL SECTION, X20;
d, VERTICAL SECTION THROUGH AN IMMATURE AND A MATURE ZONE, X20. MIDDLE ORDOVICIAN (CHAs-
MOPS) LIMESTONE, OSTROGOTHIA, SWEDEN.

Favosites hemisphericum Kutoraa, Beitr. zur Paleontologie und Geogn. Dorpats,
1837, p. 40, pl. 9, fig. 3.

Calamopora jfibrosa E1cHWALD, Silur. syst. in Ehstl., 1840, p. 197.

Chetetes petropolitanus LONSDALE, in Murchison, Verneuil, and Keyserling, Russia
and Ural, vol. 1, 1845, p. 596, pl. A, fig. 10.—Krysrruine, Reise in d. Pet-
schoraland, 1846, p. 180.—D’OrbBrany, Prodr. de Pal., vol. 1, 1850, p. 25.—
Epwarps and Hare, Mon. des Pol. foss., 1852, p. 263.

Monticulipora petropolitana Epwarps and Hamme, Brit. Foss. Cor., 1854, p. 264.—
Scumipt, Archiv fur Naturk. Liv.-, Ehst- u. Kurlands, vol. 2, ser. 1, 1858,
p. 228.

Not Dianulites petropolitanus DyBowsxt and other authors.

Zoarium massive, discoid when young but with age becoming hemi-
spheric to spheroidal; base circular, often concave and covered with

314 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

a concentrically wrinkled epitheca. Average specimens are several
centimeters in diameter, but examples as wide as 15 cm. occur.
Upper surface celluliferous, smooth; macule inconspicuous, com-
posed of more numerous mesopores and of zoccia larger than else-
where. Zocecial apertures polygonal, averaging 0.50 mm. in diam-
eter, with three in 2 mm.; walls thin. Mesopores variable in size
and shape, and rather numerous.

The shape of the zoarium and the internal characters of the Swedish
specimens studied by Nicholson are shown in figure 192, while thin

FiGc. 193.—DIPLOTRYPA PETROPOLITANA. @, TANGENTIAL SECTION, X20, SHOWING NUMEROUS MESOPORES;
b, A PORTION OF THE SAME, X35, ILLUSTRATING SIMPLICITY OF WALLS; c, VERTICAL SECTION, X8, WITH
USUAL ARRANGEMENT OF DIAPHRAGMS; d AND €, PORTIONS OF A VERTICAL SECTION, X20, WITH A FEW
CURVED DIAPHRAGMS. KEGEL BEDS (D2), KEGEL, ESTHONIA.

sections of Russian examples are illustrated in the following figures.
In tangential sections the absence of acanthopores, the tenuity and
simple character of the walls, and the polygonal shape of both zoecia
and mesopores are most noticeable. The most important specific -
character is seen in vertical sections or in vertical fractures showing
the tabulation. In the mesopores the diaphragms average a tube
diameter apart, thus, in comparison with the zocecial tubes giving a
crowded effect. The same average holds for the zocecia proper,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 315

although the distribution of diaphragms is not so regular. In the
immature zone these structures are horizontal and are placed from
two to a single tube diameter apart. The mature zones are recog-
nized almost solely by the crowding of the diaphragms, three or four
of which occur in the space of one diameter. Here, too, they are often
curved; indeed, in some tubes a few cystiphragms are introduced.
This crowding and the curved diaphragms are well shown in the
mature zone of Nicholson’s vertical section (fig. 192 d), while an
occurrence of cystiphragms is illustrated in figure 193 d. The usual

Fic. 194.—DIPLOTRYPA PETROPOLITANA. @, SMALL PORTION OF A TANGENTIAL SECTION, X8; b, PARTS OF
SAME SECTION, X20; c, VERTICAL SECTION, <8, WITH TWO MATURE ZONES EOUNDING AN IMMATURE REGION;
d, PORTION OF SAME, X20, SHOWING THE BEADED WALLS AND ALSO TWO MESOPORES REPLACED BY A
ZOG@CIUM. LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND OF DAGO, ESTHONIA.

distribution of diaphragms for the species is shown in figure 194,
where another peculiarity of the species as well as the genus is illus-
trated, namely, the change of a mesopore into a zocecium.

As pointed out by Ulrich,’ Diplotrypa petropolitana is closely allied
to D. westoni Ulrich from the Trenton formation of Manitoba, Canada,
but the few diaphragms of the latter will distinguish it. The large
zocecia and rather crowded tabulation distinguish D. petropolitana
from all described members of the genus. Compared with associated

1 Contr. Micro-Pal. Cambro-Sil., pt. 2, 1889, p. 30.
92602°—Bull. 77—11 22 ie Oars

316 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

massive species with complete diaphragms, Hallopora dybowskii is
very similar in many respects, but its zocecial tubes contain so few
diaphragms that they often appear to be wanting. The other species
have noticeably smaller zocecia as well as other differences, while
associated hemispheric forms of other genera have very distinct
internal characters.

Occurrence.—Nicholson’s type-specimens of Diplotrypa petropolitana
were collected in the Ordovician (Chasmops) limestone in Ostrogothia,
Sweden. Typical specimens from the same limestone at Rabeck,

Fs 2

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s

ma
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VAY,
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FACE ESAS
ea
YA

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)

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TL
ZT?

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Fig. 195.—DIPLOTRYPA PETROPOLITANA. @, VERTICAL SECTION, <8, OF A SPECIMEN SHOWING NUMEROUS
CURVED DIAPHRAGMS; b, PORTION OF THE SAME SECTION, X20, WITH FUNNEL-SHAPED DIAPHRAGMS IN ONE
OF THE ZO@CIAL TUBES; c, ANOTHER PORTION, X20, SHOWING A FEW CYSTIPHRAGM-LIKE STRUCTURES;
d, VERTICAL SECTION, X20, THROUGH A MACULA; ¢€, A TANGENTIAL SECTION, X20, SHOWING THE USUAL
ARRANGEMENT AND SHAPE OF ZOGCIA AND MESOPORES, LYCKHOLM LIMESTONE (F1), KERTEL, ISLAND
oF DAGo, ESTHONIA.

island of Oeland, are in the collections of the United States National
Museum and the British Museum.

Tn Russia the species occurs in all the strata ranging from the Glau-
conite limestone (B2) to the lower part of the Lyckholm (F1). The
more important localities represented by specimens in the collections
of the United States National Museum are: Glauconite limestone
(B2), Echinospherites limestone (C1), and Kuckers shale (C2), Reval,
Esthonia; Kuckers shale (C2), Erras, and Baron Toll’s estate,

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 317

Esthonia; Jewe limestone (D1), St. Mathias, Baron Toll’s estate, and
Paeskull, Esthonia; Kegel limestone (D2) Kegel, Esthonia; Wassa-
lem beds (D3), Uxnorm, Esthonia; Wesenberg limestone (EZ), Wesen-
berg, Esthonia; Lyckholm limestone (F1), Lyckholm and Lechts,
Hsthonia, and Hohenholm, Kertel, Paope, and Keilo, island of Dago.

Plesivotypes.—Cat. Nos. 57430 to 57449, U.S.N.M.

British Museum, specimens and thin sections from various localities
in Russia, and the island of Oeland.

DIPLOTRYPA BICORNIS (Eichwald).
Plate 5, figs. 3-3d; text figs. 196-198.

Dianulites bicornis Ercawa D, Zool. spec., vol. 1, 1832, p. 181, pl. 2, fig. 15.

Chextetes heterosolen KEYSERLING, Beobachtungen auf einer Reise in das Pet-
schora-Land, 1846, p. 181, fig. a, 6.—EpWwarps and Haims, Monogr. des
polyp. foss., 1852, p. 273.

Monticulipora heterosolen Scumipt, Archiv. fur Naturk. Liv-, Ehst- und Kurlands,
vol. 2, ser. 1, 1858, p. 228.—MiLtnE-Epwarps, Hist. nat. des Cor., vol. 3,
1860, p. 274.

Ceriopora bicornis Erchwaup, Lethzea Rossica, vol. 1, sec. 1, 1860, p. 413, pl. 25,
fig. 3.

Callopora heterosolen DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-For-
mation, 1877, p. 119, pl. 4, figs. 3a-d.

Cfr. Diplotrypa limitaris Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 286, fig. 18.

Commencing in the Glauconite limestone and continuing through
the Wassalem beds is a species of Diplotrypa equally as abundant as
theassociated D. petropolitanaand Hallopora? dybowsku. This species
was first described by Hichwald as Dianulites bicornis, his illustra-
tions being presented
below as figure 196.
Dybowski gave a full
description and nu-
merous figures of the
species, but adopted
Keyserling’s specific
name heterosolen, for
the reason that the
term bicornis was ap-
plicable to only a par-
ticular form of growth.

Although this is true,

Fic. 196.—DIPLOTRYPA BICORNIS. @, AN EXAMPLE OF THE USUAL
the rules of nomencla- FORM, NATURAL SIZE; 6 AND c, TWO VIEWS OF THE SURFACE, EN-
ture demand the use LARGED. COPIED FROM EICHWALD’S FIGURES OF CERIOPORA

: BICORNIS. ‘‘CALCAIRE A ORTHOCERATITES,’? PULKOWA, GOVERN-
of the earlier name a : ate ae

MENT OF ST. PETERSBURG.
adopted above.
Although extremely variable in form, the zoarium of Diplotrypa
bicornis is massive and more or less hemispheric. Young specimens
are regularly hemispheric in shape with a wrinkled epithecated base

318 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

often preserving the impression of the object upon which growth
started. Continued unequal development in certain parts of such
regularly formed zoaria result in the irregular masses figured by
Dybowski (pl. 5, fig. 3). An irregular mass with two conspicuous
horn-like projections was selected as the type of Dianulites bicornis
by Eichwald. In some cases two normally shaped zoaria may be
joined, the base of the younger adhering to the top of the older speci-
mens, or, again, curious double forms may occur by continued growth

Fic. 197.—DIPLOTRYPA BICORNIS. @, VERTICAL SECTION THROUGH THE BASAL PART OF A ZOARIUM, X20,
SHOWING THE OUTER PORTION OF THE MATURE REGION OBSCURED BY DEPOSITS OF TISSUE; 6, SMALL POR-
TION OF THE SAME SECTION ENLARGED TO EXHIBIT DEPOSITION OF TISSUE MORE CLEARLY; C, A TANGENTIAL
SECTION, X20, PASSING FROM THE REGION OF NORMAL ZOGCIA AND MESOPORES INTO THE AREA OF APER-
TURES WITH GREATLY THICKENED WALLS. THE ORDINARY INTERNAL STRUCTURE OF THIS SPECIES IS
SHOWN IN FIG. 198, DRAWN FROM THIN SECTIONS PREPARED FROM THE SAME SPECIMEN GIVING THE STRUC-
TURE FIGURED ABOVE. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

of certain zocecia of a lower zoarium into a second more or less regular
example. Celluliferous surface usually smooth, but in a few exam-
ples the macule have been observed to form low rounded monticules.

Zocecial tubes polygonal, five to six in 2mm. Mesopores of vari-
able size and number, most numerous in the maculze where they
isolate the zocecia. Walls of both zocecia and mesopores thin in the
immature zone and in the mature region of the younger stage of a

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 319

colony. The oldest portion of a zoarium the base and the edge of
the celluliferous surface, exhibits a dense, solid surface to the unaided
eye, but when magnified, this region is seen to be made up of minute,
thick-walled, round to hexagonal cells of a uniform diameter. In

oY On ne ie Crea)
ish Orieiiaan itege.

ed
7
a
ee
a
rg
A
i an =

Ay Sea BUN ce tse a a
7 Dire B Hy

Fig. 198.—DIPLOTRYPA BICORNIS. @, TANGENTIAL SECTION, X20, SHOWING THE SHAPE, SIZE, AND ARRANGE-
MENT OF ZOG@CIA AND MESOPORES IN THE MATURE ZONE. ‘THE MESOPORES ARE SHADED FOR CONVEN-
IENCE OF RECOGNITION; 6, PART OF THE SAME SECTION, 40; c, VERTICAL SECTION, X20, SHOWING THE
REGULAR AND CLOSE ARRANGEMENT OF TABULE IN THE MESOPORES AND THEIR IRREGULAR DISTRIBU=
TION IN THE ZOGCIA; d, VERTICAL SECTION, X40, ILLUSTRATING THE NORMAL DISTRIBUTION OF DIA-
PHRAGMS IN THE TWO KINDS OF TUBES. HERE ONE OF THE ZOG@CIA REPLACES TWO MESOPORES. ‘THIN
SECTIONS OF THE BASAL PART OF THIS SAME ZOARIUM ARE SHOWN IN FIG.197. JEWE LIMESTONE (D1),
BARON TOLL’S ESTATE, ESTHONIA.

tangential sections through this and the adjacent normal celluliferous
area, the zocecial walls are seen to become so thickened by the deposit
of a dense tissue that the diameter of the orifice is the same as that
of the mesopores. Thesame thickening of the walls is well exhibited in
vertical sections where the mesopores also are noted to be invested

320 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

with a similar but thinner deposit of the same tissue. Small or
young zocecia naturally show little of this thickening, but in the
usual examples, the dense, solid basal portion may be considered as a
character of value in the identification of the species.

The internal characters seen in tangential sections have been
mentioned. Aside from their smaller size and the thickening noted
above, the zocecial tubes are quite similar to those of other Diplotrypas.
Tn vertical sections, aside from the usual, somewhat beaded walls, the

marked characteristic in all good species of the genus is the abundant .

development of diaphragms in the zoccial tubes. In the immature
zone these are seldom farther apart than the diameter of two tubes,
while in the crowded portions of the mature region, two and sometimes
three occur in the width of a zoecium. Altogether the diaphragms
are more uniformly distributed in both regions than in other species
of the genus. In the mesopores these partitions maintain their
usual distribution of about their own diameter apart.

In size of zocwcia and distribution of diaphragms, Dzplotrypa
bicornis agrees well with the American D. limitaris, described by
Ulrich from the Nematopora bed of the Trenton in Minnesota. The
few mesopores of the Minnesota species will serve to separate the two,
although it is probable that D. limitaris is the American representative
of the common Russian form.

Diplotrypa bicornis is an excellent species of the genus and may be
distinguished from associated forms by the comparatively small size
of its zocecia and the abundant development of diaphragms. D. petro-
politana, D. hennigi, and D. moniliformis have noticeably larger
zocecia. Difficulty may be experienced in separating certain speci-
mens of D. heragonalis. Here, however, the zoccia, although quite
similar in size, have few diaphragms, while the mesopores are much
more closely tabulated.

Occurrence—Abundant in most of the divisions ranging from the
Glauconite limestone to the Wassalem beds. The specimens illus-
trated are from the Jewe limestone (D1), Baron Toll’s estate. Among
other localities are: Glauconite limestone (B2), Reval; Echinospherites
limestone (C1), at Reval, 4 miles east of Reval, and at Duboviki;
and in the Kuckers shale (C2), Baron Toll’s estate and Erras; and in
the Chasmops limestone, south of Bédahamn, island of Oeland.

Plesiotypes.—Cat. Nos. 57450 to 57458.

British Museum, thin sections of figured type, and specimens from
various localities in Russia and island of Oeland.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 821
DIPLOTRYPA MONILIFORMIS, new species.
Text fig. 199.

Cir. Diplotrypa neglecta Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt.1,
1893, p. 287, fig. 19.

The species for which the above new name is proposed is closely
related to the form described by Ulrich from the Nematopora bed of

Fig. 199.—DIPLOTRYPA MONILIFORMIS. d, SIDE VIEW OF A ZOARIUM, NATURAL SIZE; 6, TANGENTIAL SEC-
TION, X20, EXHIBITING MESOPORES MORE NUMEROUS THAN USUAL; c, VERTICAL SECTION, X8, PASSING
THROUGH SEVERAL SUCCESSIVE MATURE AND IMMATURE REGIONS, ILLUSTRATING THE VERY IRREGU-
LAR CRENULATED WALLS AND THE SIMILAR TABULATION OF BOTH SETS OF TUBES; d, PORTION OF THE
SAME SECTION, X20, SHOWING WALL STRUCTURE MORE CLEARLY. JEWE LIMESTONE (D1), BARON
TOLL’S ESTATE, ESTHONIA.

the Trenton formation at Hader, Minnesota, as Diplotrypa neglecta.
Each agrees in having irregularly arranged polygonal zoccia with
rather few mesopores, variable in size and distribution, and often
distinguished from the zocecia with difficulty. The aspect in vertical
section is likewise very similar, although the irregularity of the walls

322 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

is more marked in the Russian species, which may be defined as
follows:

_ Zoarium a dome-shaped or hemispheric mass about 20 mm. wide
and 12 mm. high. Surface smooth, macule inconspicuous, and dis-
tinguished mainly by the presence of more numerous mesopores.
Zocecia polygonal, irregularly arranged, three to four in a space of 2
mm. Mesopores of irregular sizes and shapes and seldom completely
isolating the zocecia. Walls of both zocecia and mesopores thin.

In vertical sections the very irregular zoccial walls are the most
striking feature, and this peculiarity alone will aid considerably in the
identification of the species. The difference in tabulation between
zocecia and mesopores is often so slight that the latter can only be
recognized by their smaller size. In many cases the mesopores
abruptly cease and their places are taken by zoccia of normal size.

Fic. 200.—DIPLOTRYPA HENNIGI. a, SIDE VIEW OF A ZOARIUM, NATURAL SIZE; 6, TANGENTIAL SECTION,
X20; c, VERTICAL SECTION, X20, SHOWING THE ZOG@CIAL WALLS BUT SLIGHTLY UNDULATING ALTHOUGH
THE MESOPORES ARE STRONGLY BEADED. KUCKERS SHALE (C2), BARON TOLL’S ESTATE, ESTHONIA.

Compared with other hemispheric bryozoans, the polygonal
zocecia and mesopores, with their crinkled walls and the uniform dis-
tribution of diaphragms, are diagnostic of Diplotrypa moniliformis.

Occurrence.—Apparently rare in the Jewe limestone (D1), Baron
Toll’s estate, near Jewe, Esthonia.

Holotype.-—Cat. No. 57413, U.S.N.M.

Thin sections of the type-specimen are in the collections of the
British Museum. ‘

DIPLOTRYPA HENNIGI, new species.

Text fig. 200.
Externally this species has much resemblance to the associated

Monotrypa jewensis, but close examination will show that its zocecia
are smaller, and that the small polygonal apertures scattered among

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 3823

the ordinary large openings are in reality true mesopores and not
young zoccia. A vertical fracture or thin section brings out more
obvious differences, as a comparison of figures 191 and 200 will
indicate. Most important of these differences are the strongly
beaded mesopores and the straight zocecial walls of D. hennigi in
contrast with the strongly crinkled walls and absence of ‘mesopores
in the Monotrypa. The zoarium of Diplotrypa hennigi is of smooth,
rounded masses composed of thin walled, polygonal zoccia with
occasional small, angular mesopores. Six of the ordinary zocecia in
2 mm. Acanthopores wanting. The specific characters are best
shown in.vertical sections, where the slightly undulated zocecial:
walls, the decided beading of the mesopores, and the paucity of
diaphragms in the zocecia proper are most diagnostic.

The specific name is in honor of Dr. Anders Hennig, of Lund,
Sweden, in appreciation of his work upon the Silurian Bryozoa of the
island of Gothland.

Occurrence.—Apparently rare in the Kuckers shale (C2), Baron
Toll’s estate, near Reval, Esthonia.

Holotype-—Cat. No. 57414, U.S.N.M.

Thin sections of the type-specimen are in the collections of the
British Museum.

DIPLOTRYPA WESTONI Ulrich.
Text fig. 201.

Diplotrypa westont Unricx, Contr. Micro-Pal. Cambro-Sil., Pt. 2, 1889, p. 30,
pl. 8, figs. 4-46; Zittel’s Textbook of Paleontology (Eng. ed.), 1896, p. 274,
fig. 457.—WHiITEAVES, Pal. Foss., vol. 3, pt. 3, 1897, p. 163.

Several specimens of Diplotrypa from the Chasmops limestone of
Sweden were at first assigned by me to a new species, but upon
close comparison I find that the differences between them and the type
of Diplotrypa westoni are too slight even for varietal distinction. The
characters of the Swedish examples are shown in the accompanying
figures. The size of the zocecium, number of mesopores, and distri-
bution of diaphragms in both sets of tubes is practically the same.
Indeed, the only difference that I can point out between Ulrich’s
figures and my own is the slightly greater number of mesopores in
the latter, a distinction removed by other specimens.

Diplotrypa westoni need only be compared with D. petropolitana,
but the more abundant diaphragms of the latter easily separate the
two, although other differences can be seen by comparing their
respective figures. The distinctive characters of D. weston are best
exhibited in vertical sections. Here the sparse tabulation of the
zocecia is most evident, but a second striking feature is the angularity
of the beading formed by the walls of the mesopores. In most

324 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

species of this genus the walls are gently undulated, but in this form
the undulations are so sharp that they are in reality angular.
Occurrence.—Rare in rocks supposed to be of Lower Trenton age
on Big Island, Lake Winnipeg, Canada. Apparently common in the
Chasmops limestone at Nittsjo Raitvik, Dalarne, Sweden, and south
of Bédahamn, island of Oeland.
Plesiotype.—Cat. No. 57415, U.S.N.M.

Fic. 201.—DIPLOTRYPA WESTONI. @ AND b, SIDE AND BASAL VIEWS OF A ZOARIUM, NATURAL SIZE; ¢, TAN-
GENTIAL SECTION, X8, THROUGH A MACULA AND ADJOINING ZOG@CIA; d, PORTION OF THE SAME SECTION,
X20; €, VERTICAL SECTION, X8, CUTTING A MACULA; f/, SEVERAL TUBES OF THE SAME, X20, ILLUSTRATING
THE ANGULARLY BEADED MESOPORES, THE REPLACEMENT OF A MESOPORE BY A ZOG@CIUM, AND THE TABU-
LATION OF BOTH SETS OF TUBES. MIDDLE ORDOVICIAN (CHASMOPS) LIMESTONE, NiTTSJO RATVIK,
DALARNE, SWEDEN.

British Museum, specimens from the island of Oeland and thin
sections of the figured specimen.

Family HALLOPORIDA, new name.

This new name in place of Calloporide becomes necessary through
the substitution of Hallopora for the preoccupied Callopora. The
family includes those integrate trepostomatous bryozoans in which
the zocecial tubes are thin-walled and attain their full size slowly,

a ce I rn TTA mc

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 325

but chiefly in which acanthopores are absent. Diaphragms are
closely arranged in the tapering proximal end, are few or wanting in
the rest of the immature region, and become crowded in the mature
zone. The earliest part of the zoccial tubes thus has the charac-
ters of mesopores. Hallopora, the type genus, is numerously repre-
sented both in individuals and species throughout the Ordovician,
Silurian, and earliest Devonian.

Genus HALLOPORA, new name.

Callopora Haut, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 400; Nat. Hist. New
York, Pal., vol. 2, 1852, p. 144.NicHoxtson, Pal. Province Ontario, 1874,
p. 61; Geol. Mag., new ser., vol. 1, 1874, p. 13.—Utricu, Journ. Cincinnati
Soc. Nat. Hist., vol. 5, 1882, pp. 154, 251.—Forrste, Bull. Sci. Lab. Denison
University, vol. 2, 1887, p. 172.—H att and Simpson, Nat. Hist. New York,
Pal., vol. 6, 1887, p. xv.—Mituer, North Amer. Geol. and Pal., 1889, p.
295.—Utricn, Geol. Surv. Illinois, vol. 8, 1890, pp. 372, 416; Geol. and
Nat. Hist. Surv. Minnesota, vol. 3, 1893, p. 275; Zittel’s Textbook of Paleon-
tology (Eng. ed.), 1896, p. 275.—Simpson, Fourteenth Ann. Rep. State
Geologist New York for the year 1894, 1897, p. 588 —NickLEs and Bass er,
Bull. 173, U. S. Geol. Surv., 1900, pp. 36, 186.—Basster, Bull. 292, U.S.
Geol. Surv., 1906, p. 40.—Cumines, Thirty-second Ann. Rep. Dep. Geol.
Nat. Res. Indiana, 1907, p. 741.—Henwnic, Archiv fur Zool., vol. 4, No. 10,
1908, p. 48.

Monticulipora (section 1) DyBowsx1, Die Chaetetiden der Ostbaltischen Silur-
Form., 1877, p. 89.

Not Callopora Gray, Norman, and LEVINSEN.

Unfortunate as it may seem to the paleontologist, the well-known
generic name Callopora Hall must, according to the rules of nomen-
clature, be replaced by another term. Nickles and Bassler recog-
nized the facts, and in their Synopsis of American Fossil Bryozoa
published the following:

In 1848 Gray (Proc. Zool. Soc. London, Appendix, 1848, and List of British Ani-
mals in the collection of the British Museum, 1848, pp. 109, 146) proposed the generic
term Callopora for a single species, the Flustra lineata of Linnzeus, but the term failed
to gain acceptance, and the species lineata is now considered to be a Membranipora. —
As Callopora Hall has become deeply engrafted into literature, it seems undesirable
under the circumstances to replace it by a new name.

However, Gray gave a description of his genus, poor as it may be
considered from the standpoint of to-day, and the important point
of his work is that he selected a type species. Callopora must, there-
fore, stand based upon this species, even though more recent work
should prove it to be a Membranipora. Such excellent authorities
in the study of recent Bryozoa as Levinsen and Norman have worked
out the details of Gray’s Callopora lineata and consider the genus a
valid one.

In view of the above, I propose the name Hallopora in honor of
the distinguished paleontologist James Hall, to replace his Paleozoic
genus Callopora. This new name seems most appropriate in com-

326 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

memoration in a small way of Professor Hall’s work upon fossil Bry-
ozoa, and particularly upon this generic group.

The zoaria of Hallopora are almost always solid ramose and bushy.
In the perfect state the apertures are closed by perforated, orna-
mental covers which, as growth proceeds, form the diaphragms of
succeeding layers.

Genotype.—Callopora elegantula Hall. Early Silurian of America
and Europe.

HALLOPORA MULTITABULATA (Ulrich).

Text fig. 202.

Monotrypella multitabulata Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv.
Minnesota, 1886, p. 100.

Callopora multitabulata Unricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3,
pt. 1, 1893, p. 280, pl. 23, figs. 11, 12, 16, 17, 24-26, 30, 31; Zittel’s Textbook of
Paleontology (Eng. ed.), 1896, p. 274, fig. 456 C, D.—Sarpzson, Journ. Geol.,
vol. 9, 1901, p. 9, pl. A, figs. 5-6d.— RurpEMaNN, Bull. 49, New York State
Mus., 1901 [1902], p. 13.—NickLEs, Kentucky Geol. Surv., Bull. 5, 1905, p.

42, pl. 1, fig. 2—Basster, Proc. U. 8. Nat. Mus., vol. 30, 1906, p. 22, pl. 1,

figs. 5-7.

Several specimens in the collections from the Wassalem beds at
Uxnorm are externally and internally so similar to examples of Hal-
lopora multitabulata from the Black River and lowest Trenton rocks
of Minnesota that were the two lots mixed they could not be sepa-

Fig. 202. HALLOPORA MULTITABULATA. @, VIEW OF TYPICAL SPECIMEN, NATURAL SIZE; 0, SURFACE OF THE
SAME, X9; c, SURFACE OF A FINELY PRESERVED EXAMPLE, X18, SHOWING THE ORNAMENTED, ZOGCIAL
COVERS; d, VERTICAL SECTION, X9, EXHIBITING THE CHARACTERISTIC CROWDED TABULATION. BLACK
RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.)

rated. One of the Russian specimens is almost an exact duplicate
of the American specimen shown in figure 202 a, while the internal
structure shown in the vertical section, figure 202 d, is repeated in
the thin sections of the foreign form.

The zoarium of Hallopora multitabulata is of more or less irregu-
larly divided subcylindrical branches with rather strongly elevated
monticules. The zoccia at the surface are angular, thin-walled,
and in close contact, about eight in 2 mm. The apertures of the

————

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 327

zocecia are often closed with ornamental opercula, as shown in figure
202 c. Mesopores are few. The most marked internal feature is
the crowded tabulation shown in figure 202 d._ In the immature zone
the diaphragms are seldom more than their own diameter apart and
frequently more closely spaced. In the mature zone six or seven
diaphragms may frequently be counted in the space of a tube diam-
eter. The few mesopores present are equally crowded.

Occurrence.—Abundant in the Black River and Lower Trenton
strata of Minnesota, Iowa, Kentucky, and Tennessee. Less common
in the Wassalem beds (D3) at Uxnorm, Esthonia (Cat. No. 57459,
U.S.N.M.).

Represented in the British Museum by a specimen and thin section
from Uxnorm. |

HALLOPORA GOODHUENSIS (Ulrich).

Text figs. 203, 204.

Callopora goodhuensis Utricz, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. ;
1, 1893, p. 282, pl. 23, figs. 9, 10, 21, 29.

This bryozoan is closely related to Hallopora multitabulata (Ulrich),
but differs in that the surface is without monticules, the average size
of the branches is less, the zocecia are smaller, especially at the center
of transverse sections, and their apertures are subangular and slightly
smaller. The internal structure is very similar, the most marked

Fic. 203.—HALLOPORA GOODHUENSIS. @ AND b, TWO FRAGMENTS OF NATURAL SIZE; C, SURFACE OF A SPECI-
MEN, X9; d, AXIAL REGION OF A TRANSVERSE SECTION, X18. CLITAMBONITES BED OF THE LOWER TREN-
TON LIMESTONE, NEAR CANNON FALLS, MINNESOTA. (AFTER ULRICH.)

difference being that the mature region is narrower. The internal
structure of a well developed Russian example is shown in figure 204.

Occurrence.—Abundant in the Clitambonites bed of the Lower
Trenton at St. Paul and other localities in Minnesota; not uncommon
in the Wassalem beds (D3) at Uxnorm, and in the Wesenberg lime-
stone (E) at Wesenberg, Esthonia.

Plesiotypes.—Cat. Nos. 57460, 57461, U.S.N.M.

British Museum, specimens and thin sections from Uxnorm.

328 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

HALLOPORA WESENBERGIANA (Dybowski).
Plate 4, fig. 2-2h; text fig. 205.

Monticulipora wesenbergiana DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 95, pl. 3, figs. 2a-h.

Dybowski records this as a very abundant species at Wesenberg
and gives a lengthy description and numerous figures of its charac-

oh

HG
a
LS

eae

jose | le

ES ae
MES fi
ee esis

Fig. 204.—HALLOPORA GOODHUENSIS. @, TANGENTIAL SECTION, X20, OF A SMALL BUT WELL DEVELOPED
RUSSIAN SPECIMEN; 6, VERTICAL SECTION OF THE SAME SPECIMEN, X20. WASSALEM BEDS(D3), UXNORM,
ESTHONIA.

ters. He fails to illustrate the tabulation, a most important char-
acter in the discrimination of such species, but I have no doubt that
the common Hallopora of the Wesenberg limestone, whose internal
characters are shown in figure 205 is Dybowski’s Monticulipora wesen-
bergiana.

MATURE ZONE; 6, TANGENTIAL SECTION, X20, CUTTING THE EARLY PORTION OF THE MATURE REGION
WHERE MESOPORES ARE BEST DEVELOPED; C, VERTICAL SECTION, X20, SHOWING CHARACTERISTIC TABU-
LATION. WESENBERG LIMESTONE, WESENBERG, ESTHONIA.

As shown in Dybowski’s figure, the branches frequently and irregu-
larly divide and average 5mm. in diameter. Their surface is smooth,
but macule of larger zowcia and more numerous mesopores are fre-

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 329

quently plainly evident to the unaided eye. The apertures are usu-
ally large, angular, thin-walled, with few mesopores, but in young
specimens particularly mesopores are more numerous and sometimes
completely isolate the zocwcia. Six zocecia in 2 mm.

The internal characters are essentially the same as in H. muilti-
tabulata. The vertical section figured shows the average distribution
of diaphragms, but in other examples the peripheral zone is broader
and contains more numerous diaphragms. Here also it is to be ob-
served that the mesopores are most common in the early part of the
peripheral zone and pinch out before the surface is reached. This
causes the variation to be observed in tangential sections. Such a
section passing through the early part of this outer region shows, as
seen in figure 205 6, rounded zocecia more or less separated by meso-
pores. The zocecia in a section taken just below the surface are
angular, partly in contact, and mesopores are comparatively few.

Comparing H. wesenbergiana with H. multitabulata, its closest ally,
it is found that the latter has smaller zoccia (eight in 2 mm.), a
tuberculated surface, and a more regular zoarium. The associated
H. goodhuensis is also quite similar, but differs in having a small,
more regularly branching zoarium, with smaller zocecia and more
regularly dividing branches. Indeed, these three species have so
much in common that it requires close discrimination to separate
them.

Occurrence.—Extremely abundant in the Wesenberg limestone (E)
at Wesenberg and other localities in Esthonia; less common in the
Wassalem beds (D3) at Uxnorm. The same species, or at least a
closely related variety, occurs rarely in the Orthoceras limestone (B3)
at Reval.

Plesiotype.-—Cat. No. 57462, U.S.N.M.

Specimens and thin sections from the Wesenberg limestone at
Wesenberg, are in the collections of the British Museum.

HALLOPORA SPLENDENS, new species.
Text fig. 206.

Cir. Callopora ampla Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 281, pl. 23, figs. 13-15, 18-20, 22, 23, 27, 28.

Zoarium of irregularly divided, stout, subcylindrical branches
averaging 10mm.in diameter. Surface smooth, macule inconspicu-
ous, 3 mm. distant from each other and made up of zoecia slightly
larger than the average. Zocecia direct, angular, with rather thick
walls for the genus, 5in 2mm. Zocecial aperture often preserving
ornamented opercula. Mesopores almost entirely absent at the sur-
face but visible in vertical sections in the bend from the immature
to the mature region. Ornamented opercula or closures are pre-
served on a few of the specimens. .

330 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

In tangential sections the zocecia are polygonal and in contact
with each other, usually on all sides. The walls are comparatively
thick, and show the original boundary line between the zoccia as a
-well defined dark line. Mesopores are few and limited almost entirely
to the macule.

Vertical sections are particularly interesting in showing the dis-
tribution of diaphragms and mesopores. As shown in figure 206 e,
the latter originate in the bend from the immature to the mature
zones, but frequently cease before the surface is reached. In some

e Nee SE

viata

eave aT

JUTIS

SES ara NTIY De, Oe ROSES TR
Faas oa 7 aS

Px
N
N

Fig. 206.—HALLOPORA SPLENDENS. @, FRAGMENTARY SPECIMEN, NATURAL SIZE; b, TANGENTIAL SECTION,
X20, CUTTING THE MOST MATURE PORTION OF THE ZOARIUM; C, USUAL ASPECT OF TANGENTIAL SECTIONS,
X20; d, VERTICAL SECTION, X20, WITH PRACTICALLY NO MESOPORES; €, ANOTHER VERTICAL SECTION, X20,
ILLUSTRATING OCCURRENCE OF MESOPORES. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

cases (see fig. 206 d) mesopores are practically absent, even in this
restricted zone. As usual the diaphragms are closely arranged in the
mesopores. In the zoccia proper diaphragms are equally abundant
as in the mesopores, in the earliest stages when the tubes are scarcely
wider than the mesopores. After the zocwcia have attained their
normal size, diaphragms are from one to three diameters distant
from each other in the immature zone, but crowded in the mature
region where 8 to 10 mm. may sometimes be counted in the length
of one diameter.

{
t

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 331

Hallopora splendens is a fine example of that section of the genus
typified by the American form H. ampla (Ulrich) in which diaphragms
are exceedingly abundant in the mature zone and mesopores are
correspondingly rare. Indeed, the species under discussion is closely
related to H. ampla, differing especially in its more robust growth,
larger and more direct zocecia, and wider mature zone. H. ampla
has six to seven zocecia in 2 mm., its mature zone is usually quite
narrow, and the zocwcia as a result are somewhat obliquely directed
at the surface. H. splendens has five zoccia in 2 mm., a wide, well-
developed mature zone, and rather thick walled, direct zoccia.

The associated form, Hallopora tolli, new species, has equally large
zocecia, but here mesopores are numerous and diaphragms are almost
entirely wanting in the zocecial tubes.

Occurrence.—Not uncommon in the Jewe limestone (D1), Baron
Toll’s estate, and at St. Mathias, Esthonia.

Holotype.—Cat. No. 57466, U.S.N.M. :

Specimens and thin sections in the collections of the British

Museum.
HALLOPORA DUMALIS (Ulrich).

Text fig. 207.
Callopora dumalis Utricu, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1,
1893, p. 282, pl. 23, figs. 1-8.
Several examples of a small, frequently branching Hallopora from
the Kuckers shale possess the characters of the American species
H. dumalis, illustrated in figure 207. The zoarium consists of num-

Fic. 207.—H ALLOPORADUMALIS. @TOd, VIEW OF FOUR REPRESENTATIVE FRAGMENTS, LIFE SIZE; €, SURFACE
OF THE SLENDER SPECIMEN, X9; f, SURFACE OF ANOTHER SPECIMEN, X18, WITH ZOG@CIAL CLOSURES PRE-
SERVED; g, VERTICAL SECTION, X18; h, TANGENTIAL SECTION, X18. PHYLLOPORINA BED OF BLACK
RIVER (DECORAH) SHALES, ST. PAUL, MINNESOTA. (AFTER ULRICH.) :

erous small branches averaging 1.5 mm. in diameter, inosculating to

form a bushy mass. Fragments of a zoarium are shown in figures

207a tod. Thesurface of these branches is smooth, with the zocecial
92602°—Bull. 77—11——23

332 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

apertures in young examples more or less oblique, ovate, and separated
by numerous mesopores. With age, the apertures become more
direct and angular, with less numerous mesopores, as illustrated in
figure 207 e. Seven to eight zoecia in 2mm. The American speci-
mens occasionally show apertures with closures marked by faint
lines radiating from a small central perforation. The internal char-
acters are sufficiently illustrated in figure 207 g and h to require no
description.

Occurrence.—Common in the Phylloporina bed of the Black River
(Decorah) shales, and in the Clitambonites bed of the lowest Trenton
at St. Paul and Cannon Falls, Minnesota. Apparently rare in the
Kuckers shale (C2) at Reval, Esthonia (Cat. No. 57468, U.S.N.M.).

Represented in the collections of the British Museum by specimens
from American localities.

HALLOPORA UNDULATA (Ulrich).
Text fig. 208.

Callopora undulata Utricu, Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minne-
sota, 1886, p. 95; Geol. Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 279,

pl. 22, figs. 24-31.
The slender, ramose branches with rather large rounded monticules
and the internal structure shown in figure 208, are sufficient to sepa-
rate this neat little Hallopora from other species of the genus. The

Fig. 208.—HALLOPORA UNDULATA. @ AND 0, TYPICAL SPECIMENS OF THE NATURAL SIZE; c, SURFACE OF
ORIGINAL OF FIGURE b, X9; d, VERTICAL SECTION, X18. BLACK RIVER (DECORAH) SHALES, St. PAUL,

MINNESOTA. (AFTER ULRICH.)

Russian examples referred to the species differ only in having a
slightly less robust zoarium, a difference which would undoubtedly
be eliminated with larger collections.

Ulrich’s description is quoted below:

Zoarium ramose, branches slender, averaging about 2.5 or 3 mm. in diameter, divid-
ing dichotomously at intervals of 10 mm. or more. Surface with rather large, rounded

monticules, that usually coalesce laterally, forming transverse ridges, or more or less
complete annulations, 5 in 10 mm. In some fragments and portions of others the

= i ——

a.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 333

monticules are separate, while in a few they are nearly obsolete. Zocecia with moder-
ately thin walls, subangular or ovate apertures, of nearly equal size over all portions
of the surface; 10 or 11 in 3 mm. Mesopores comparatively few, small, not readily
distinguished externally, their mouths usually closed. Zocecial covers not observed.

Occurrence.—Common in the Black River (Decorah) shales at
Minneapolis and St. Paul, Minnesota, and in the Wassalem beds (D3)
at Uxnorm, Esthonia (Cat. No. 57469, U.S.N.M.).

British Museum, specimen and thin section from Uxnorm.

Fic. 209.—HALLOPORA TOLLI. @, SMALL FRAGMENT, NATURAL SIZE; 0, TANGENTIAL SECTION, X20, SHOW-
ING LARGE, THIN-WALLED-ZOGCIA WITH NUMEROUS MESOPORES; C AND d, TWO PORTIONS OF A VERTICAL
SECTION, X20, EXHIBITING TABULATION. KUCKERS SHALE (C2), REVAL, ESTHONIA, AND JEWE LIME-
STONE (D1), BARON TOLL’S ESTATE.

HALLOPORA TOLLI, new species.

Text fig. 209.

This well marked species forms smooth, cylindrical branches 6 to 8
mm. in diameter, very much like H. wesenbergiana, but differing con-
spicuously in having much larger zoecia. Internally the two are
quite distinct, as a glance at the figures, especially of vertical sec-
tions, willshow. In tangential section, H. tollc exhibits its polygonal
to rounded, thin-walled zocecia, four in 2 mm., with a fair number of
small, angular mesopores. In the macule the mesopores are occa-
sionally numerous enough to isolate the zocwcia, but elsewhere they
are seldom so abundant.

334 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Besides the large zocecia and numerous mesopores, the tabulation
is quite distinctive for this species. In the zocecia proper, three or
four diaphragms are inserted in the earliest portion of a tube; then
they are practically absent until the close of the mature zone, when
a few mesopores are occasionally found. ‘The mesopores, as in other
species of the genus, are closely tabulated throughout.

While the present species is quite different from associated bryo-
zoans, it is closely related to a new species occurring in the lowest
Trenton strata at Belleville, Canada. Indeed, the two agree in all
respects save the occurrence of more numerous mesopores in the
Russian form.

Occurrence.—Rare in the Jewe limestone (D1), Baron Toll’s estate,
Kuckers shale (C2), Reval, and in the Kegel limestone (D2), Kegel,
Esthonia.

Cotypes.—Cat. Nos. 57470 to 57472, U.S.N.M.

HALLOPORA ELEGANTULA (Hall).
Text fig. 210.

Callopora elegantula Hatt, Nat. Hist. New York, Pal., vol. 2, 1852, p. 144, pl. 40,
figs. la-m.—Utricu, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 250,
pl. 11, figs. 6-6b.—Smeson, Fourteenth Ann. Rep. State Geologist New
York for the year 1894, 1897, pl. 18, figs. 1-7 —Bassuer, Bull. 292, U.S. Geol.
Surv., 1906, p. 41, pl. 17, figs. 11-15; pl. 26, fig. 12.

Callopora nana NicHotson, Ann. and Mag. Nat. Hist., ser. 5, vol. 13, 1884, p. 120.

In breaking up limestone from the Borkholm formation, several
fragments of a large celled Hallopora were found, which, upon study
with thin sections, proved to be identical with the wide spread early
Silurian species H. elegantula. This species has been described and
figured on several occasions, so that I need only point out its diag-
nostic features.

The zoarium is of smooth branching stems 3 to 5 mm. in diameter,
with large, rounded, thin-walled zocecial apertures, four to five in
2 mm., separated by a variable number of mesopores. The aper-
tures are frequently closed by ornamental covers, as shown in figure
210 f. The characteristic tabulation of both zoccia and mesopores
is illustrated in figures 210 d and e, while an ordinary tangential sec-
tion through the mature zone is shown in figure 210 c. That the
perforated closures become the tabule of succeeding zoccia is evi-
dent from figure 210 a.

The smooth stems and the large, rounded apertures with numerous
mesopores in addition to the internal generic characters, will readily
serve to distinguish this species.

Occurrence.—Abundant in almost all of the early Silurian strata of
North America. Hall’s types came from the Niagaran (Rochester)
shale of New York. In Europe the species is known from the Wen-
lock shales of England and in the equivalent strata on the island of

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 335

Gothland, where the name Callopora nana has been applied to it by
Nicholson. The Russian specimens were derived from the Lyckholm
limestone (F1), Kertel, island of Dago (Cat. No. 57474, U.S.N.M.),

we
eee
TR
BS IN
Fic. 210. HALLOPORA ELEGANTULA. @, TANGENTIAL SECTION, X18, WITH THREE OF THE ZOGCIA SHOW-
ING OPERCULA; 0, TRANSVERSE SECTION, X18, ILLUSTRATING THE SHAPE OF THE ZOG@CIA AND MESOPORES
IN THE IMMATURE REGION; ¢, TANGENTIAL SECTION, X20, THROUGH THE MATURE ZONE; d AND é€, TWO

VERTICAL SECTIONS, X18 AND X20, SHOWING SLIGHT DIFFERENCES; f, SURFACE VIEW OF SEVERAL ZOGCIA,
X20, SHOWING PERFORATED CLOSURES. NIAGARAN (ROCHESTER SHALE), LockPpoRT, NEW YORK.

and the Borkholm limestone (F2), at Borkholm, Esthonia (Cat. No.
57475, U.S.N.M.).
Specimens from American localities in the British Museum.

HALLOPORA ? DYBOWSKEII, new species.
Plate 5, figs. 1-1l; text figs. 211, 212.

Callopora nummiformis DyBowskt (part), Chaetetiden der Ostbaltischen Silur-
Formation, 1877, p. 109, pl. 4, figs. la-l (part).—Nicnotson, Man. of Paleon-
tology, 1889, p. 348.

Not Callopora nummiformis Haut, Nat. Hist. New York, Pal., vol. 2, $852, p. 148,
pl. 40, figs. 5, 5a.

Associated with Dviplotrypa petropolitana in the Russian and
Swedish Middle Ordovician formations is a hemispheric bryozoan so
similar in almost all respects that an examination of a vertical sec-
tion or fracture is necessary to distinguish it. This new species is
quite as abundant as its associate and the most conspicuous differ-
ence, without the examination of thin sections, is in its sparing devel-
opment of diaphragms. Under the name of Callopora nummiformis

336 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

Hall, Dybowski figured a vertical section (see pl. 5, fig. 1 7), which is
undoubtedly of this form. His tangential section (figs. 1-1 e) may
also be from specimens of the same species. His figures 1 f to 1 h,
however, are undoubtedly based upon thin sections of Prasopora
simulatriz Ulrich, an abundant hemispheric bryozoan in the Trenton
strata of America. Dybowski erroneously identified these several
species with Callopora nummiformis Hall, a small, discoid bryozoan
from the Silurian rocks of New York and Indiana. The latter species,
which belongs to Mesotrypa, a genus of the Monticuliporide, has been
figured by the present writer,! and comparison will show the error of
Dybowski’s identification.

oi)
Fig. 211.—HALLOPORA ? DYBOWSKI. @, TANGENTIAL SECTION, X20, WITH ZO@CIA LESS ANGULAR THAN
USUAL; b, VERTICAL SECTION, X8, SHOWING CURVED DIAPHRAGMS; C, SEVERAL TUBES OF THE SAME, X20.
WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA.

So far as the zoarial characters go, the description of Diplotrypa
petropolitana will apply to the present form in every respect, and even
the internal structure is somewhat similar. Tangential sections of
the two species are almost identical. Slight differences exist, but
these can not be described as permanent because of the variation in
each in shape of zocecia and number of mesopores. In vertical sec-
tions the widely separated diaphragms, three to ten tube diameters
apart, in the zoccial tubes of H.? dybowskw, are in marked contrast
with the numerous diaphragms of the similar species. That this is a
constant difference was shown by a study of over one hundred speci-
mens of both species, each specimen falling into its particular place,
with no intermediate forms. Continuing the comparison with D.
petropolitana it is found that H.? dybowski does not possess the
beaded walls characteristic of Diplotrypa. Moreover, as in other

i Bull. 292, U.S. Geol. Surv., 1906, pl. 10, figs. 1, 2.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 3837

species of Hallopora, its diaphragms have at one time served as
closures for the zocecia, as shown in Dybowski’s figure 1 7 of plate 5.
The presence of these ornainental, centrally perforated closures, the
rounded zocecia and closely tabulated mesopores with straight walls,
and the absence of acanthopores, cause me to place the species in the
genus Hallopora. The growth is not in accord with this genus, nor
does the tabulation of zocecia strictly agree, so, for this reason, I am
questioning the generic identification.

C
ae
a

Fic. 212.—HALLOPORA ? DYBOWSKI. @, SIDE VIEW OF A SMALL EXAMPLE, NATURAL SIZE; 0, BASAL VIEW
SHOWING WRINKLED EPITHECA AND CICATRIX OF ATTACHMENT; Cc, AN AVERAGE TANGENTIAL SECTION,
X20; d, VERTICAL SECTION, X8, SHOWING THE NORMAL FEATURES OF THE SPECIES; €, PORTION OF THE
SAME, X20; f, A LONG VERTICAL SECTION, X8, EXHIBITING THE DISTRIBUTION OF DIAPHRAGMS. TWO
OF THE ZO@CIAL TUBES REPLACE MESOPORES. JEWE LIMESTONE (D1), BARON TOLL’S ESTATE, ESTHONIA.

By examining a moistened longitudinal fracture with a hand lens
no difficulty will be experienced in separating associated hemis-
pheric bryozoans from this species. The specific name is in honor
of the excellent pioneer work of Dr. Dybowski upon Paleozoic
Bryozoa.

Occurrence.—Abundant at various localities in Esthonia in forma-
tions ranging from the Echinospherites limestone (C1) to the Wesen-
berg (KE). The particular localities represented in the collection of

338 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

the U. S. National Museum are Reval and Gastilizy, in the Echino-
spherites limestone (C1), Baron Toll’s estate, in the Kuckers shale
(C2) and Jewe limestone (D1), and at Wesenberg, in the Wesenberg
limestone (EK). The species also occurs in the Chasmops limestone
on the island of Oeland, Sweden.

Cotypes.—Cat. Nos. 57473, 57476 to 57480, U.S.N.M.

A fragment of the sectioned type and two thin sections from the
Jewe limestone, Baron Toll’s estate, and specimens from the Chas-
mops limestone, island of Oeland, are in the collections of the British
Museum. .
HALLOPORA? TENUISPINOSA, new species.

Text fig. 213.

This interesting species, in manner of growth and tabulation has
much in common with other species of Hallopora, but differs from all
the described forms in the development of rather numerous shallow
acanthopores. These are plainly visible at the surface of well
preserved specimens, but they are seen in thin sections only when the
outermost part of the peripheral zone is cut.

The zoarium of this species is of dwarfed stems seldom branching
more than once. The specimen shown in figure 213 is a typical
example of a complete zoarium. The surface is smooth and presents
no well-marked macule, although groups of slightly larger zoecia
can be discovered upon close observation. The zocecial apertures
are thin walled and vary from a rounded to polygonal shape, accord-
ing to the number of intervening mesopores. In the mature condi-
tion, three to five small, sharp acanthopores project from each
zocecial wall. Four and one-half to five zocecia in 2 mm.

In vertical sections the tabulation of both sets of tubes is seen to
be essentially the same as in the usual species of Hallopora. In the
zocecial tubes, diaphragms are abundant in the earliest part of the
immature zone, and are then wanting almost entirely throughout the
rest of the tubes. In the mesopores, the cross partitions average
their own diameter apart. Their place is almost always marked by a
constriction of the walls, producing the beaded effect most conspicu-
ous in Diplotrypa.

Tangential sections show thin-walled, rounded to polygonal
zocecia with numerous mesopores. Occasionally two zocecia are in
contact and then exhibit the dark divisional line of the Integrata.
The exceptional feature of such sections is the occurrence of small
acanthopores, which, however, are seldom as numerous as at the sur-
face itself. 'These acanthopores are very shallow and, as a rule, are
included in thin sections only accidentally.

This species is referred to Hallopora because of its general zoarial
and zocecial structure. The acanthopores and beaded mesopores are

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 339

features indicative of the Trematoporide, but until more species are
known, I prefer to classify the present form as a doubtful Hallopora.
Occurrence.—Common in the Wesenberg limestone (KE) at Wesen-
berg, Esthonia. Less common in the Kegel limestone (D2) at Kegel,
Esthonia.
Holotype.—Cat. No. 57481, U.S.N.M.

Fic. 213.—H ALLOPORA ? TENUISPINOSA. @, AN ORDINARY FRAGMENT, NATURAL SIZE; b, TANGENTIAL
SECTION, X20, SHOWING A FEW SMALL ACANTHOPORES; C, PORTION OF THE SAME, X35, WITH THE STRUC-
TURE OF ZO@CIA AND ACANTHOPORES MORE CLEARLY EXHIBITED; d, VERTICAL SECTION, X20, WITH CHAR-
ACTERISTIC TABULATION; €, PORTION OF A TRANSVERSE SECTION, X20. WESENBERG LIMESTONE
(E), WESENBERG, ESTHONIA.

A thin section of the type-specimen is in the collections of the
British Museum.

UNDETERMINED GENERA AND SPECIES.

Although I have attempted to identify all of the Russian Ordo-
vician forms previously described, it happens that there are still
quite a number so poorly defined and figured that I at least am able
to do nothing with them. In all of these cases, so far as J am aware,
the original types are either lost or are not distinguished. Should

340 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

some future student be able to discover these types, and from their
study give a clear idea of the forms, unrecognizable at present, the
generic and specific names, according to the rules of nomenclature,
will date from his work, and should synonyms of species herein
described be discovered, the standing of the latter will not be invali-
dated. For the sake of convenience, these unrecognizable genera
and species are discussed in alphabetical order. In the following
notes reference is also made to genera and species from the Russian
Ordovician deposits incorrectly placed in the Bryozoa, or worth
mentioning for other reasons.

Genus ARCHEOPORA Eichwald.
Archeopora ErcHwatLp, Letheea Rossica, vol. 1, 1860, p. 405.

The eight species described under this genus by Eichwald range in
time from the Ordovician to the Carboniferous, and undoubtedly
embrace a number of generic types. No type species is mentioned,
and the first species, Archeopora lamella may be accepted as the geno-
type. The generic character, according to Eichwald, is that the
bryozoan consists of a single incrusting, calcareous layer, made up of
circular cells [zoccia] isolated from each other by minute pores
[mesopores]. Such a zoarium and arrangement of zocecia and meso-
pores occurs in a number of genera, and, without further data, the
genus 1s unrecognizable.

ARCHEOPORA LAMELLA Eichwald.
Text fig. 214.

Archeopora lamella Eicowaup, Lethza Rossica, vol. 1, 1860, p. 405, pl. 24, figs.

17, 18.
The description of this species contains no characters of any value
other than that the zoarium is incrusting with the cells rounded and
separated from each other by minute pores. Hichwald’s figures are

Fig. 214.—ARCHEOPORA LAMELLA. EICHWALD’S VIEWS OF HIS TYPE-SPECIMENS, ONE (@ AND b, NATURAL
SIZE AND PNLARGED) SHOWING MESOPORES, AND THE SECOND (¢ AND d) APPARENTLY WITH SOLID
INTERZOG@CIAL SPACES.

here reproduced, but without knowing the particular horizon and lo-
cality of the originals, and the amount of magnification, none of which
is given, one can hardly even make a guess as to the species.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 341

It is also most likely that a number of forms was grouped under
this name, since the occurrence of the species is given as the Ordo-
vician [nastione, in the vicinity of Zarskoje, Wesenberg, and Erras,
and the Stneee. strata on the island of Oesel and s
at Kamenetz Podolsk.

ARCHEOPORA ANGULOSA Eichwald.

Text fig. 215. a ese
: oo ase esa®
Archeopora angulosa Eicnwaup, Lethzea Rossica, vol. 1, ey ‘eres
0 p. 410, pl. 26, fig. 2 ‘elegance’
1860 p. 410, pl. 26, fig. 2. seo e ase

This species forms thin, incrusting expansions 5,, 915 Aancunorora
upon Echinospherites in the Ordovician limestone ncutosa. a anv 6,
© THE INCRUSTING TYPE-
at Pulkowa and at Wesenberg, the figured Specimen. curt) ae
being from the latter locality. Both the zocecia sux anp sntancxp,
d indicated: in-iemren2ioueare ams fa.” Cues
and mesopores, as indica g ; ee ee ee
gular, differing in that respect from A.lamella. JI mesoporzs. (ArTER
am unacquainted with an incrusting form of this ™™”4™?
sort from either Pulkowa or Wesenberg, but even were such specimeas
before me, more specific characters than are given by Eichwald would

be necessary before an identification of any value could be made.

ARCHEOPORA PUNCTATA Eichwald.
Text fig. 216.

Archeopora punctata E1cowap, Lethzea Rossica, vol.
1, 1860, p. 406, pI. 24, fig. 19.

The description of this species includes more
details than that of any other of the various
Ordovician forms referred to the genus, and it
is possible that the new species, Favositella
punctata, described in this volume, is based
upon the same form. For this reason I have
ee selected ‘the same name for the supposed new

TATA. @ AND b, THE TvPe- Species of Favositella and have indicated its

Meee NacuRALsmn ANY =6possible identity with Archeopora punctata in

ENLARGED. ORDOVICIAN ‘4 ‘

“uMrstonE, Doreasa River, thesynonymy. LHichwald describes Archeopora

GOVERNMENT OF St, PETERS: punctata as a thin, rounded, lamellar expan-

BURG. (AFTER EICHWALD.) i : ;

sion, with thick-walled, oval cells radiately

arranged. One end of the cell is higher than the other [lunarium],
and ten rows of cells occur in the space of a line. Eichwald’s figure
also bears a resemblance to those of the Favositella, but in spite of
these several facts one can not be certain of the identity of A. punctata
until the type or authentic specimens are restudied.

Occurrence.—Archeopora punctata was recorded from the Ordovician
(Orthoceratite) limestone along the Dolgaja River, Gdow district,

342 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

government of St. Petersburg. Favositella punctata is common at
Uxnorm, Esthonia, in the Wassalem beds (D3).

ARCHEOPORA RADIANS Eichwald.
Text fig. 217.
Archeopora radians Er1cHwaup, Lethza Rossica, vol. 1, 1860, p. 408, pl. 24, fig. 20.

The figures of this species indicate without the slightest doubt that
it is founded upon the basal side of some parasitic bryozoan. As many
forms would present the same or a quite similar appearance from this
side, it is obviously impossible
to recognize the particular
one Eichwald figured. The
species must, therefore, be
classed as unrecognizable.

Occurrence.—Ordovician
limestone, near Pulkowa and
Wesenberg.

CALAMOPORA ALVEOLARIS Goldfuss.

Calamopora alveolaris Goup-
Fuss, Petref. Germ., vol. 1,

Fic. 217.—ARCHEOPORA RADIANS. @ AND b, THE TYPE- 1826, p. 77, pl. 26, fig. 1.—
SPECIMEN, NATURAL SIZE AND ENLARGED. (AFTER EIcHWwa.p, Lethea Rossica,
EICHWALD.) vol. 1, 1860, p. 466.

Russian specimens from various horizons and localities have been
identified as above by Eichwald with this species, which, as figured by
Goldfuss, is a typical Favosites. The Ordovician specimens so referred
have certainly little in common with the latter form.

CALAMOPORA FIBROSA Goldfuss.
Calamopora fibrosa var. tuberosa ramosa GoLDFuss, Petref. Germ., vol. 1, 1826, p.
82, pl. 28, fig. 3.
Calamopora fibrosa Erichwaup, Lethza Rossica, vol. 1, 1860, p. 469.

Under this name Hichwald described one or more of the numerous
massive Russian bryozoans, but which can not be determined. Gold-
fuss’s species is likewise so figured and described that it can not be
recognized.

Eichwald records the species from both Ordovician and Silurian
localities of Baltic Russia.

CALAMOPORA POLYMORPHA Goldfuss.
Calamopora polymorpha Gotp¥Fuss, Petref. Germ., vol. 1, 1826, p. 79, pl. 27, figs.
2-5.—EIcHWALD, Letheea Rossica, vol. 1, 1860, p. 466.

The Ordovician specimen so identified can not be recognized from
Eichwald’s description, but are certainly very different from the
Devonian fossils figured by Goldfuss under this name.

Occurrence.—Identified in Russian Ordovician at Pulkowa, Erras,
and Wesenberg, as well as in later horizons at various localities.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 343
CALAMOPORA RETICULATA Eichwald.
Text fig. 218.

Calamopora reticulata Ercawaup, Lethza Rossica, vol. 1, 1860, p. 469, pl. 23,
figs. 6 a, b.

The Ordovician specimen figured by Eichwald under the above
name is probably a well-preserved fragment of Hemiphragma panderi
(Dybowski). This identification can not of course be made positively
without a study of the figured example, but the ramose zoarium, shape
of zocecia, absence of mesopores, and especially the arrangement of the
numerous acanthopores recall the Hemaphragma.

CALLOPORA LIGNIFORMIS Dybowski.
Plate 5, fig. 5, 5 a.

Callopora ligniformis DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-Form.,
1877, p. 116, pl. 4, figs. 5, 5a.

According to Dybowski, the zoarium of this species is of cylindrical,
solid, ramose, smooth branches, with an internal LOUTH much like
his Callopora nummiformis. I have not come ¢@
across specimens with these characteristics and
can not place the species.

Occurrence.—Probably in the Wassalem beds
(D3), Wassalem and Erras, Esthonia.

CALLOPORA PIRIFORMIS (Eichwald).
Plate 5, figs. 6, 6a, 6b.

Dianulites piriformis Erchwatp, Zool. spec., vol. 1, 1832,
p. 1Stple:2> figs’ 12s

Chetetes piriformis EichwaLp, Lethza Rossica, vol. 1,
1860, p. 478. ee

Callopora piriformis DyBowskt1, Die Chaetetiden der ig. 218,—Caramorora

Ostbaltischen Silur-Form., 1877, p. 117, pl. 4, fig.6 | RETICULATA. @ AND 6,
a b ZOARIUM NATURAL SIZE
AND SURFACE EN-

Although this species seems to have been aaa VASUEEE (RUGS
fairly well figured by Hichwald and later by
Dybowski, I am unable from either their descriptions or figures to
place it definitely. Dybowski mentions the great resemblance of its
internal structure to that of his Callopora nummiformis (= Hallopora ?
dybowski), but his figures, although bearing out his remarks in part,
show an almost complete absence of diaphragms in the zoccial tubes.
At any rate, Dianulites pirvformis must be regarded as one of the
undetermined species.

Occurrence.—¥ormation B, Pulkowa, government of St. Petersburg.

344 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

DIANULITES APICULATUS (Eichwald).
Plate 2, figs. 7, 8; text fig. 219.
Millepora apiculata ExcHwatp, Inter ingrica, 1825, p. 21.
Orbitulites apiculatus ErcHwauD, Zool. spec., vol. 1, 1829, p. 150, pl. 2, fig. 3.
Chextetes apiculatus Exchwaup, Lethza Rossica, vol. 1, 1860, p. 479, pl. 28, figs.
1 a-d.
Dianutlites apiculatus DyBowsxt, Die Chaetetiden der Ostbaltischen Silur-Form.,
1877, p. 32, pl. 1, figs. 7; 8.

Hichwald’s figures and description of Chetetes apiculatus are of
practically no value in distinguishing it from the numerous other
massive Russian bryozoans. Dy-
bowski’s treatment of the species
is but little better. My guess
regarding the species is that it is
founded upon small examples of
Dianulites petropolitana, or some
: other massive bryozoan with
Fic. 219.—DIANULITES AFICDEATUS: @ TO d, FOUR the base covered by a layer of

VIEWS OF EICHWALD’S .TYPE OF CH#TETES 5
APICULATUS; ¢, CELLULIFEROUS SURFACE EN- the smaller, thick-walled, closely
LABGED: SCO Sae Ecaw AED.) tabulated mesopore-like cells.

Occurrence-—Dybowski cites Erras, Duboviki, Pulkowa, and

Popowa as localities.

DIANULITES HAYDENI Dybowski.
Plate 2, figs. 11-11).

Dianulites haydenii DyBowskt, Die Chaetetiden der Ostbaltischen Silur-Forma-
tion, 1877, p. 37, pl. 1, figs. 11 a—b.

Although Dybowski gives a detailed description and figures the
internal structure of this species, he shows no characters which
enable me to recognize what particular form he had in mind. With-
out a restudy of the type-specimens, if they are available, I fear that
Dianulites haydenwi can not be recognized.

Occurrence.—Middle Ordovician, Wesenberg and Wassalem.

DIANULITES SULCATUS Dybowski.
Plate 2, figs. 12-126.

Dianulites sulcatus DyBowsk1, Die Chaetetiden der Ostbaltischen Silur-Forma-
tion, 1877, p. 38, pl. 1, fig. 12a, b.

The figures of this species are clearly of some Homotrypa or Homo-
trypella, but for lack of specimens from the type locality, I am unable
to decide the relationship of the form. If the zoarial growth shown
by Dybowski is constant, this alone should help in identifying the
species.

Occurrence.—Probably Lyckholm limestone, Kertel, island of Dago.

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 845
ESCHARIPORA RECTA Eichwald.

Escharipora recta Erchwatp, Lethea Rossica, vol. 1, 1860, p. 435, pl. 27, figs.
8a-c.
Not Escharopora recta Hau.

The species referred by Eichwald to Hall’s Escharopora recta, a well
known bryozoan from the Trenton formation of New York, has no
relationship to this or any other bryozoan, but is allied to Recepta-
culites and Ischadites. The latter alliances were recognized by
Eichwald, since he placed his description of Escharipora recta next
to those of Ischadites. His error was in the identification of his
species, and not in its classification.

Occurrence.—Eichwald cites the species as from the ‘‘Calcaire 4
Orthoceratites,”’ island of Dago.

Genus MICROPORA Eichwald.

Micropora Ercowaup, Lethzea Rossica, vol. 1, 1860, p. 393.

The status of this genus has been indicated on page127. Micropora
gracilis Kichwald, the first species, proves to be a valid species of
Stictoporella, and the generic name Micropora might have...
been retained instead of Stictoporella had it not been ree

O% 2
. . AS
employed by Gray previously for another generic type of sate
¢,
bryozoans. ete ‘
MICROPORA RHOMBICA (Eichwald). Sx
SRO

Text fig. 220. Fic. 220.—M1-
: CROPORA
Eschara rhombica EicHwaLD, Urwelt Russlands, vol. 2, 1847, p. 43, RHOMBICA.

plean Miee ss FRAGMENT
Micropora rhombica EtcHwaLp, Bull. Soc. Nat. des Moscou, 1855, p. CERO E
458; Letheea Rossica, vol. 1, 1860, p. 395. eee

ORDOVICI-
Eichwald’s description of this species is of little value $v .5.00
for accurate determination, but the original of his figure, (Arter
reproduced here, is in all probability a species of Escharo- 9 "**”?
pora. EH. subrecta is the only Russian species of the genus so far
noted, and it is possible that Micropora rhombica refers to the same
form. Should Eichwald’s type be discovered and found to be the
same as Escharopora subrecta, this would not affect the synonymy,
since Micropora rhombica can not be considered as sufficiently de-
scribed and figured to be recognized.

Occurrence.—‘‘Calcaire & Orthoceratites de Reval.”’

Genus MYRIOLITHES Eichwald.

Myriolithes E1cowaup, Letheea Rossica, vol. 1, 1860, p. 450.

Although this genus was described as a member of the tabulate
corals, it is probable that the type-species, MV. fastigiatus is a ramose
monticuliporoid bryozoan. Neither EHichwald’s figure nor descrip-

346 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

tion is sufficient to determine the matter, and until his type-speci-
mens are restudied, the genus can not be considered valid. The other
three species referred to Myriolithes by Eichwald are from
Carboniferous strata and undoubtedly belong to a genus
distinct from the Ordovician type.

; .y MYRIOLITHES FASTIGIATUS (Eichwald).
ae Text fig. 221.

Millepora fastigiata Exchwaup, Observat. de Trilobit., 1825, p. 21.

Eater Myriapora fastigiata EIcHWALpD, Bull. Soc. Nat. Moscou, 1856, p. 88.
PAGHIGTATIOS. Myriolithes fastigiatus Excnwaup, Lethza Rossica, vol. 1, 1860,
a, THE TYPE- p. 450, pl. 26, fig. 13a, 6.
wae, 9 Chedact ing thi i ted ab Th
cae e facts concerning this species are noted above. e

SIZE AND species can not be recognized from either the description
SLIGHTLY
entarcev. OF figure.

GED ORE: Occurrence.—‘‘Calcaire & Orthoceratites de Poulkowa.”
CIAN, PUuL-

nee any MONTICULIPORA OVULUM Eichwald.

ERNMENT

ee ae Monticulipora ovulum Ercawatp, Lethza Rossica, vol. 1, 1860,
TERSBU. 5

(AFTER p. 492, pl. 25, figs. 8a—d.

EICHWALD.)

Although this is registered as a Monticulipora by Hich-
wald, his figured specimen is undoubtedly a coral like Heholites and

not a bryozoan.
ORBIPORA FUNGIFORMIS Eichwald.

Text fig. 222.
Orbipora fungiformis E1cHwatp, Lethzea Rossica, vol. 1, 1860, p. 485, pl. 28, fig.
Aa, b, ¢.

Fic. 222.—ORBIPORA FUNGIFORMIS. @ AND b, CELLULIFEROUS AND EPITHECATED SIDES OF THE TYPE-
SPECIMEN; C, CELLULIFEROUS SURFACE ENLARGED; d, BASAL SIDE, ENLARGED. HOHENHOLM, ISLAND OF
DaGgo. (AFTER EICHWALD.)

HKichwald’s description and figures are the only ones of any value
that have ever been published regarding this species. As shown by

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 347

the figure here introduced, little can be said about the species except
that it is a massive bryozoan, apparently. Before the species can be
considered valid, the internal structure of the type must be described
and figured.

Occurrence.—Hohenholm, island of Dago, probably in the Lyck-
holm limestone.

Genus PTEROPORA Eichwald.

Pteropora EicHwa.p, Letheea Rossica, vol. 1, 1860, p. 395.

According to Hichwald, this genus is related to pe uprodas McCoy,
but differs in having a celluliferous tissue
connecting the lateral branches. It is
in this very character that the genus is
peculiar and unlike any other fenestellid or
similar bryozoan. Eichwald possessed only
a single specimen of each of his species, and 5... 953 _prenorora PENNULA.
as these were attached to the rock he did ano 0, Excnwat’s views oF
not determine the nature of the opposite face. mm anp unuancu>. Onpowe
None of the specimens in the various collec- — “AN, StitHaM, EstHonta.
tions I have studied has shown the characters ascribed to Pteropora.

PTEROPORA PENNULA Eichwald.
Text fig. 223.

Pteropora pennula Erchwatp, Lethea Rossica, vol. 1, 1860, p. 396, pl. 23, figs.
15a, b.
As remarked above, I have been unable to identify this species,
and, in accordance with my plan of including
identified species only in the main body of
this paper, this and the following form must
remain uncertain.
Occurrence.—‘‘Calcaire & Ortheratites,”’
Spitham, Esthonia.

PTEROPORA EXILIS Eichwald.

Fig. 224PTEROPORA EXILIS. @ Text fig. 224.
AND 0, ZOARIUM NATURAL SIZE ae >
ENLARGED. ORDOVICIAN, ER- Pteropora exilis Ercowap, Lethza Rossica, vol. 1,
RAS, ESTHONIA. (AFTER EICH- 1860, p. 397.
WALD.)

All that is known of this species isshown in the accompanying figure.
Occurrence.—‘‘Calcaire 4 Orthoceratites,’’ Erras, Esthonia.

PTILOPORA DISTICHA Goldfuss.

Glauconome disticha GotpFuss, Petref. Germ., vol. 1, 1827, p. 217, pl. 64, fig. 15.
Ptilopora disticha Eicowaup, Lethza Rossica, vol. 1, 1860, p. 383.

Under the above name Eichwald identified a species supposed to be
the same as the widespread Silurian form now known as Pennirete-
92602°—Bull. 77—11——24

348 BULLETIN 77, UNITED STATES NATIONAL MUSEUM.

pora disticha. Eichwald’s specimens were recorded from the inflam-
mable, argillaceous shale (Kuckers, C2), near Erras. I have not seen
this form and the identification is probably incorrect.
Genus RHABDINOPORA BEichwald.
Rhabdinopora Ercawatp, Lethsea Rossica, vol. 1, 1860, p. 368.

This genus was described as belonging to the Bryozoa, an error
which is now well known since its genotype,
Rhabdinopora flabelliformis is the widespread
form best known as Dictyonema flabelliformis.
In our list of foreign genera, Nickles and
myself included Rhabdinopora among the
Bryozoa with the comment ‘‘seems to be a
Fig. 225.-Srrcrorora scatremm. Lenestellid with one row of cells to the branch;

FORMIS. @, EIcHwat’sricuRE this is a type unknown to us, unless it be a
OF THE SURFACE ENLARGED; ° °
b AND c, E1cuwatp’s onrawat case of defective observation.’’ The present
FIGURE OF THE SAME SPECIES. allusion to Rhabdinopora is to correct the
error of its reference to the Bryozoa.
STICTOPORA SCALPELLIFORMIS (Eichwald).
Text fig. 225.
Eschara scalpelliformis Er1cowaup, Urwelt Russlands, vol. 2, pl. 1, fig. 1; Lethza
Rossica, vol. 1, 1860, p. 391, pl. 33, fig. 3a, 30.

The two type-specimens of this species as shown by the accom-
panying figures, are undoubtedly different. I have not encountered
any specimen which might be identified with either
one of thetypes. Without an actual restudy of these
types, the species can not be considered as valid.

Occurrence.—‘‘Calcaire & Orthoceratite,’”’ Reval
and Erras.

VINCULARIA MEGASTOMA Eichwald.
Text fig. 226.

Vincularia megastoma ErcHwatp, Lethzea Rossica, vol. 1,
1860, p. 402, pl. 24, fig. 9.

This species is registered from several post-Ordo- sia ae
vician localities and from the middle Ordovician at — yrseasroma. aanvb,
Wesenberg. If the figured type came from Wesen- = TYP E-SPeciuen, X1
berg, and is correctly illustrated, the species is un- OS dk ee te
doubtedly a Nematopora closely allied to N. granosa SAME. _ (AFTER Ercu-
Ulrich? from the lowest Trenton beds at Cannon ~~”

Falls, Minnesota. The collections from the Wesenberg limestone have
afforded no specimens of this kind, and until the type locality of V.
megastoma is known, the species can not be identified with certainty.

1 Synopsis of American Fossil Bryozoa, Bull. 173, U. S. Geol. Surv., 1900, p. 57.

2 Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, p. 196, fig. 20; Geol. and Nat. Hist. Surv. Minnesota,
yol. 3, pt. 1, 1893, p. 205, pl. 3, figs. 17-20.

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EXPLANATION OF PLATES. |
Puate 1.

Geologic map of the Russian Baltic Provinces (after von Schmidt).
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BULLETIN 77 PL. 1

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(AND CAMBRIAN)

?OVINCES OF RUSSIA

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SKETCH MAP OF THE SILURIAN (AND CAMBRIAN)

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SECTION FROM MALLA & KUNDA IN ESTHONIA ON THE GULF OF FINLAND TO TALKHOF IN LIVONIA.
FROM PROF. GREWINCK’S GEOLOGICAL MAP OF ESTHONIA, LIVONIA, & COURLAND.

SECTION THROUGH THE WESTERN COAST REGION OF ESTHONIA, FROM WERDER TO ODENSHOLM.

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PLATE 2.
[After Dybowski.]

This and the three following plates, copied from Dybowski, are about two-thirds of
the size as published by him. In the descriptions of these plates the generic and spe-
cific names are as given by Dybowski, while the horizon and locality were obtained
from his descriptions. Notes by the present writer are enclosed in brackets.

Dianulites fastigiatus Eichwald.

Fig. 1. Transverse section through middle portion of zoarium.
2.-Tangential section near surface of colony.
3. Vertical section.
Zone 1 [B], Reval, Pulkowa, etc.

Dianulites petropolitanus Pander, sp.

iN

. Tangential section.
. Vertical section.
Zones 1 and 2 [B], various localities.

Or

Dianulites petropolitanus var. hexaporites Pander.

6. Side view of zoarium, 2/3.
6a. Surface of zoarium, 2/3.
Zone 1 [B], Reval, Pulkowa, Popowka.

Dianulites apiculatus Eichwald.

7. Tangential section cutting the basal zone of small cells.
8. Vertical section.
Zone 1 [B], Pulkowa, Popowka, etc.

Dianulites rhombicus (Nicholson).

9. Tangential section of zoarium.
Zone 2 [EK], Wesenberg.

Dianulites elegantulus (Fr. Schmidt).

10, 10a. Two fragments of zoaria.
106. Tangential section.
10c. Vertical section.
Zone 8 [Silurian], Ohhesare-pank and Kattripank.

Dianulites haydenit, new species.

11. Side view of fragment, <2/3.
lla. Tangential section through mature zone.
11b. Vertical section.

Zone 2 [E], Wesenberg.

Dianulites sulcatus, new species.

12. Fragment of zoarium, X2/3.
12a. Vertical section.
126. Tangential section.
Zone 2 [D], Kertel, island of Dago.

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PLATE 3.
[After Dybowski.]
Trematopora cingulata, new species.

1. Fragment of zoarium, natural size.
1b. Tangential section.
Zone 1 [C], Kuckers, Sack.

Trematopora cingulata var. nodosa, new variety.

la. Fragment, 2/3.
Zone 2 [D], Wait.

Trematopora variabilis, new species.

2. Portion of zoarium, about natural size.
2a. Tangential section.
Zone 2 [D], Wassalem.

Trematopora variabilis var. complanata, new variety.

3. Fragment of a zoarium, 2/3.
3a. Tangential section.
Zone 2 [D], Wassalem.

Trematopora colliculata Kichwald.

4. Transverse section.
4a. Tangential section.
4b. Vertical section.

4c. Tangential section showing arrangement of zocecia, acanthopores, and

mesopores.
Zone 2 [D], Worms, etc.

Dittopora anulata Eichwald, sp.

5. Tangential section.
Zone 1 [B], Popowa.

Trematopora pustulifera, new species.

6. Tangential section.
Zone 2 [D], Wassalem.

Dittopora claveformis, new species.

7. Three zoaria, X2/3.

7a. Vertical section.

7b. Tangential section.
Zone 1 [B], Pulkowa.

Orbipora arborescens, new species.
8. Zoarium, 2/3.
8a. Tangential section.
8b. Transverse section of branch.

Zone 8 [Silurian], Lode.
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EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

Orbipora panderi, new species.

9. Fragment of zoarium, 2/3.

9c. Vertical section.

9a and 6. Tangential sections.
Zone 1 [C], Kuckers.

Orbipora distincta Kichwald.

10. Tangential section.
10a. Enlarged portion of same.
106. Vertical section.

Zone 1 [C], Erras, Reval, etc.

Solenopora spongioides, new species [not a bryozoan].

11. View of organism, X2/3.
lla. Tangential section, greatly enlarged.
11b. Vertical section.

Zone 3 [E], Herkiill.

300

PuateE 4.
[After Dybowski.]

Monticulipora rugosa Edwards and Haime.

Fig. 1. Tangential section introduced for comparison.

Upper Ordovician [Maysville], Cincinnati, Ohio.
Monticulipora wesenbergiana, new species.

2. Fragment of zoarium, natural size (Wesenberg).
2a. Another fragment, 2/3 (Wait).

2b. Base of zoarium attached to foreign body, 1 (Wesenberg).

2c, d, e. Different views of another basal part of a zoarium.
2f. Tangential section.
2g. Tangential section through the ee part of a zoarium.
2h. Another tangential section.

Zone 2 [E], Wesenberg and Wait.

Monticulipora, sp.
3. Tangential section.
3a. Same, more enlarged.
Zone 2 [D], Wassalem.

Trachypora porosa, new species [not a bryozoan].

4. Fragment of a colony, X3.
4a. Surface, enlarged.
Zone 8 [Silurian], Kaugatomo-pank, Ohhesare-pank.

Monticulipora edilis Eichwald, sp.

5. Tangential section of a mature specimen.
5a. Vertical section.
Zone 2 [E], Wesenberg.

Labechia conferta Lonsdale, sp. [not a bryozoan].

6a. Tangential and vertical sections.
Silurian, Dudley, England.

7a. Tangential and vertical sections of Russian example.
Silurian, Hoheneichen.

Stellipora revalensis, new species.

8. Portion of a zoarium, X2/3.
8a. Tangential section.
8b. Vertical section.

Zone 1 [C], Reval.

Stellipora constellata, new species.

9. Tangential section.
9a. Vertical section.
Zone 2 [?F], Hohenholm.

306

BULLETIN 77 PL. 4

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EARLY PALEOzOIC BRYOZOA OF THE BALTIC PROVINCES.

Fig.

PLATE 5.
[After Dybowski.]
Callopora nummiformis Hall.

la, 6. Three tangential sections (Kuckers).

le. A tangential section showing more angular zocecia (Reval).

1d, e. Two tangential sections (Wesenberg).

1f, 1g, 1h. Two tangential and a vertical section of a Prasopora from Cincinnati,
incorrectly referred here.

lt. Surface of a zoarium showing covers to apertures (Wesenberg).

1k. Surface showing monticules.

1l. Vertical section showing characteristic tabulation of zocecia and mesopores
(Kuckers).

Zones 1 and 2, various localities.

Heliolites dubia Fr. Schmidt [not a bryozoan].

2a. Tangential and vertical sections. -
Silurian, Hapsal.

Callopora heterosolen Keyserling.

3. Outlines of variously shaped zoaria (Reval, Erras, Kuckers, and Baltisch-
port).
3a. Vertical section through the upper part of a zoarium.
3b. Vertical section through the basal part of a zoarium.
3c and d. Tangential sections through the upper and basal parts of the zoarium,
respectively.
Zone 1 [B—D], various localities.

Callopora maculata, new species.

4. Fragment of a zoarium, natural size.
4a. Vertical section.
4b. Tangential section.

Zone 8 [Silurian], Ohhesare-pank.

Callopora ligniformis, new species.

5. Tangential section.
5a. Vertical section.
Zone 2 [D], Wassalem.

Callopora piriformis Eichwald sp.

6. Three zoaria, X2/3.
6a. Tangential section. +
6b. Vertical section.

Zone 1 [B], Pulkowa.

308

U. S. NATIONAL MUSEUM

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EARLY PALEOzZOIC BRYOZOA OF THE BALTIC PROVINCES.

PLATE 6.
Corynotrypa schucherti Bassler.

Fig. 1. The type-specimen, 3, incrusting a species of Streptelasma.
Wesenberg limestone (E), Wesenberg, Esthonia. .

Ceramopora intercellata, new species.

2. Surface of the type example, X18, showing portion of a macula of mesopores
and the adjoining zoecia.
Lyckholm limestone (F1), Hohenholm, island of Dago.

Ceramopora invenusta, new species.

3. Surface of the type, <9, partially obscured by clay, exhibiting the irregular
zocecia and numerous granules.
Wesenberg limestone (E), Wesenberg, Esthonia.

Anolotichia revalensis, new species.

4, Celluliferous side of a thin, flat expansion, 1.5, with groups of larger zocecia
indistinctly shown.
5. Surface of the same example, 9, showing the angular zocecia, few meso-
pores, and crescentic lunarium.
Orthoceras limestone (B3), Reval, Esthonia.

Anolotichia rhombica, new species.

6. A zoarium attached to a rock fragment, 1.5, showing the concentrically
wrinkled epitheca.
7. Celluliferous surface of the same specimen, X18, illustrating the rhomb-
shaped zocecial apertures.
Wesenberg limestone (E), Wesenberg, Esthonia.

Mitoclema boreale, new species.

8. Six fragments, <6.
Wesenberg limestone (E), Wreseaeas, Esthonia.

360

U. S. NATIONAL MUSEUM BUEPEEING iho

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

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Figs. 1,

3.

11.

12.

PLATE 7.
Stictoporella gracilis (Eichwald).

2. Two zoaria, natural size, showing the expanded, attached base and the
_ cribrose branches.
Surface of original of fig. 1, 12.

Glauconite limestone (B2), Wassilkowa, government of St. Petersburg.

Stictoporella cribrosa Ulrich.

. Fragment of a zoarium, 1.5, preserving the expanded, attached base.

Wassalem beds (D3), Uxnorm, Esthonia.

Coscinium prenuntvum, new species.

. A rather complete zoarium, natural size, showing the cribrose branches and

attached basal portion.

. Surface of the same, X12, exhibiting the prominent lunaria and the papillose

interzocecial spaces.
Orthoceras limestone (B3), island of Rogo, Esthonia.

Phyllodictya flabellaris, new species.

. The incomplete, flabellate type-specimen, natural size.
. Surface of same, X12, showing a solid macula and adjoining zocecia.

Orthoceras limestone (B3), island of Rogo, Esthonia.

Spatiopora lineata incepta Ulrich.

. Life-size view of the Russian specimen referred to this variety.
. View of the surface of the same, <4.

Wesenberg limestone (E), Wesenberg, Esthonia.
Anolotichia impolita Ulrich.

Surface of a Russian example of this species, <4.
Kuckers shale (C2), Baron Toll’s estate, Esthonia.

Coeloclema crassimurale, new species.

Surface of a basal expansion, 4, referred to this species.
Jewe limestone (D1), Baron Toll’s estate, Esthonia.

362

U. S NATIONAL MUSEUM

EARLY PALEOZOIC BRYOZOA OF THE BALTIC

PROVINCES.

BULLETIN 77 PL. 7

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PLATE 8.
Pachydictya flabellum (Leuchtenberg).

Fig. 1. A nearly complete zoarium, X1.5.
Wesenberg limestone (EZ), Wesenberg, Esthonia.

Graptodictya proava (Hichwald).

2. Surface of portion of a branch, X18, showing striated noncelluliferous border
and several adjoining rows of zocecia.
Wassalem beds (D3), Uxnorm, Esthonia.

Graptodictya bonnemai, new species.

3. Magnified view, X18, of branch.
Kuckers shale (C2), Baron Toll’s estate, Esthonia. .

Graptodictya obliqua, new species.

4. Surface of the type-specimen, <8.
Lower part of Lyckholm limestone (F1), Kerkill, Esthonia.

Pseudohornera bifida (Eichwald.)

5, Celluliferous side of portion of a zoarium, 6.
Kuckers shale (C2), Baron Toll’s estate, Esthonia.

{364

U. S. NATIONAL MUSEUM BULLETIN 77 PL. 8

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

PLATE 9.
Graptodictya proava (Eichwald).

Fig. 1. Nearly complete zoarium, X1.5.
2. Fragment, X2, showing the striated base pointed for articulation.
3. View, natural size, of an old, average example.
4, Surface, <5, of another fragment.
5, Fragment of a rock, X2, containing a solid, ramose bryozoan, to which is
attached the cuplike, attached basal expansion of this species.
Wassalem beds (D3), Uxnorm, Esthonia.
6. View, natural size, of the American example of this species described by
Sardeson as Stictoporella cribrosa.
Lower part of Trenton limestone, Kenyon, Minnesota.

366

U. S. NATIONAL MUSEUM BULLETIN 77 PL. 9

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Hemiphragma glabrum, new species.

Nearly complete zoarium, natural size.
Wassalem beds (D3), Uxnorm, Esthonia.

Hemiphragma subsphericum, new species.

. Surface, <8, of one of the specimens of text fig. 179, showing the thin-walled

apertures with semidiaphragms exposed.
Wesenberg limestone (E), Wesenberg, Esthonia.

Batostoma mickwitzi, new species.

. Nearly complete zoarium, one-half natural size.

. A complete, unbranched, small zoarium, two-thirds natural size.
. Branching fragment, two-thirds natural size.

. Surface of original of preceding, <8.

Wassalem beds (D3), Uxnorm, Esthonia.

Dianulites petropolitana Dybowski.

. Surface, <8, of the typical form of the species.

Orthoceras limestone (B3), Reval, Esthonia.

. Epithecated, basal side of a specimen of the form hexaporites, natural size.
. Celluliferous face of a specimen of the same form, slightly enlarged, in which

the hexagonal outline is produced by covered mesopores opening on a plane
with the ordinary zocecia.
Surface of the same specimen still further enlarged.
Glauconite limestone (B2), Tswos, on the Wolchow River, government
of St. Petersburg.
Surface of a specimen, natural size, showing hexagonal areas present in one
portion and absent in the rest of the figure.
Glauconite limestone (B2), Granaja Scheldicha, government of St.
Petersburg.

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Nicholsonella gibbosa (EKichwald).

Figs. 1-5. Five zoccia of various sizes and shapes, X 1.5.
6. Surface of the original of fig. 1, X 18.
Glauconite limestone (B2), Wassilkowa, government of St. Petersburg.

Dittopora colliculata (EKichwald).

7-10. Four small examples, natural size, with distinctly elevated macule.
11-14. Four specimens of the usual size and surface features.
15. A nearly smooth example, natural size.
Wassalem beds (D3), Uxnorm, Esthonia.

Dittopora annulata (Eichwald).

16. Portion of a zoarium, X 1.5, with indistinct macule.
Orthoceras limestone (B3), island of Rogo, Esthonia.
17. An example, 1.5, preserving the parasitic basal portion, and showing
distinct ring-like macule. ;
Glauconite limestone (B2), Tswos, on the Wolchow River, government
of St. Petersburg.

Dittopora claveformis (Dybowski).

18-23. A group of specimens, X2, exhibiting various forms of growth.
24, Fragment of a brachiopod, X1.5, with the basal portions of two examples
attached.
Glauconite limestone (B2), Tswos and other localities, government of
St. Petersburg.

Trematopora cystata, new species.

25. Surface of a well-preserved example, X15.
Kuckers shale (C2), Reval, Esthonia.

370

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EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES.

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Piate 13.

Surface of a slab of limestone from the Wassalem beds, illustrating the abundance of
fossils in this formation. The large, reticulate specimen with a solid, spreading base,
in the middle portion of the plate, is of the abundant Homotrypella cribrosa, the ribbon-
like, cribrose frond in the upper part of the plate represents Graptodictya proava; a
fragment of Favositella? punctata lies just below the center of the plate. Most of the
slender, ramose specimens are young examples of Dittopora colliculata.

Wassalem beds (D3), Uxnorm, near Reval, Esthonia.

374

BULLETIN 77 PL. 13

U. S. NATIONAL MUSEUM

EARLY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES

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(Synonyms are in italics.)

Page.
abrupta, Corynotrypa.....-------.--.------- 65
acanthophora, Orbipora...........----.---.- 255
PATCANIENO POLES a= = )oirciae eierwieris ee eee atelata stirs 48
Acknowledgments......-.-..-------------- Bol Pe
PACH NOSENOMOs = = we winine c= selec eels we 175
Vdilis; CladOPOT@ =.) «wis lee iscle = ese ie oicl- oe cine 242
eedilis Hiridothy pave. tance eee cece sel 242
minor, Eridotrypa.....-..-.--------- 245
exdilis, Monticulipora.......-.-.-------+----- 242
alveolaris, Calamopora......-----.---------- 342
Nam aloamatac s\ccicce mete ccstacele eaten ici 177,178
American and Baltic Ordovician Bryozoa,
Summanyuol Po ccccesiesewins secs oete telsee ets 32
ampla; Callopora neces elec cence ese ereree eee 329
Amplexopora...... Fe oe Nee e ek ERIN reel aacrs 178
Amplexopora winchelli.......--...----------- 278
PAIMpPleXOPOrI Gee en opr ni-u cee eco tome eal state 178, 265
eA a polais Ota Beyer paeleee siete eieeeeyeetaetrste et ters oie 178, 297
mirabile ss .\; cose tase eres 298
Comat NSS aaSS: 299
angulata, Retepora.............--..-------.- 169
angulosa, Archeopora...-...-----.----------- 341
annlatas DivuOpOVa sec ses sees wees ee 304
annulatus, Chexietes.2- 52. -2.-- 2-2-2201 -- +--+ 304
AMOIOUICHI a) cjascie soe sacetct telaeeeteen escecles 91
breviporals sj: 32:.7 Bees secs 94
Impolitansscceeen eee et ee ec ce ce 97
ponderosa......-..------2------- 91
revalonsis.~2222222: Ws 20 2... - 95
rhombicas= 22.032 ek oa. 92
BACCHUS cs sre ss hoe es Se. 98
antheloidea, Stellipora.............-.---- west? 22k
Anthozoa,- Wist ofa shc-22425 5225420 Se 19
antiqua, Gorgonia........-...-..--.--------- 175
apiculain, Millepora...-..2:-.-.2s22---2----- 344
apiculatus, Chettetes......--.-----2--2--0---+- 344
apiculatus, Dianulites......-...-.....-----.- 344
apiculatus, Orbitulites.....-.-.-.-.----+------ 344
apsendesoides, Stellipora.............-.---.- 223
arachnoidea, Aulopora.....--.--------------- 60
arachnoidea, Stomatopora.......-....-.....- 60
arborea bispinulata, Monticulipora.......... 179
Monticulipora ..........--...-.---.- 179
PATCHEO POLO = = sce Psst eee Coase cece ta 340
aN gUMOSA TAs Ls see SR ee eee 341
lamella......- HSM ORES M SAAS 340
MUNCtatae ese esceecene ---- 105,341
TAGIANSE AHS hes PERERA ee ete 342
Arctic America, Ordovician and Early Silu-
mianrstratanolss) sent esettees aes ee 32
eiinatum Arthroclema: 222 ss -ccs see ee: 151
Arthroclema.......-.-.. coosedsoucsacsoobens 150
ALTIMA se cee eee eee 151
pulchellumrs ss soe keene eee 150

Page.
PAINT ONEMOcicienncrete nei cece coe eee te oe 147
Arthropora caus sek os cen G cece ee ones eae eac eee 119
simplex}. j.2cs 2 cemeciseeatee os. 120
ATthrostylidsete entero ckeceeeeseeeeescciect 146
YArthrostyluses ccc cence cc coke Cee eee eee 147
ObLIQHUS VERE eee oe 148
aspera, Spatiopora......-....--.--------- eed 06
Aspidoporacesescteeee ces sceoee saeetateeoe ee 177
MGACLOPOFA: 2c ecncnc ct ece wee sects oeneccmacts 178
Atactoporellacs.:-¢.i22.2 2. Soto Se ee 177
Atactoporella crassd...-...------------------- 193
WAulopondscs2224ssscseccueccs seseesoee d+ +e 59
OVACHNOIMED 4522-522 ee ose ee eee 60
AUlOPONAUSP:.225s55s2e25e552225-2220eecssee 68
Baltic and American Ordovician and Early
Silurian Bryozoa, Summary of........... F 18
Baltic area, Paleontology of.......-.-...-..-- 19
Baltic Ordovician and Early Silurian Bryo-
zoa, Table showing range of...........-.-- 50
Baltic Sea area, General Geology of........-.. 4
Baltic Sea area, Map of........-...-..--..-.- 5
Baltic Sea area, preservation of fossils in..... 4
barberi, Corynotrypa-.+.-..----------------- 63
batheri, Hemiphragma................-..-.- 296
BatostOMa nae eecs ones see eee cee soeseee 178, 272
BALOSLOMMAss Satccsee cso teat eee eeeoeee es 281
Batostoma fertile............------------.--- 274
Cireulares see eee ene 275
granwlosumey ees tase ceeice ea 280
IB OLOSTOMIONIN CS Uae seme aaa ee eee etal 284
Batostoma magnopora ............--------.. 272
mickwitzi sete esses cs cssscines 276
Wwinchellisssttet tes Ps ss een ees 278
spinulosum........-.... 279
Batostomellidcatscess eee sce seers eae 178, 240
bicornis, Ceriopora.-....-..--.--------------- 317
Digniililes ser neee Boe ete hes cea 317
bicornis, Diplotrypa.....-.--.--.---.---.--.- 317
bifida, Pseudohornera....-.---.--..-.------- 173
iyi, TH ODTOTIIOUDaccoescdoccsocedesecscesne 173
bifurcata, Pachydictya...................... 143
bifurcata, Stictopora......-..--.-------------- 143
Black iver Scoupe-cceseeesccseeeeeeee eee eee 27
Blue clay and associated strata........-..... 10
bonnemai, Graptodictya........--.--.---.--. 122
boreale, Mitoclema.........-.-..-.....--..-- 69
Borkholm Bryozoa, List of.......-....-.-.-- 7
limiestones hy 2 eee eee neon se 16
Borkholmiensis, Rhinidictya?............... 143
Brachiopoda, List of........-....--.--------- 20
previpora, Anolotichia............-.-.-.----- 94
Bryozoa in Cambrian strata.............--.-. 10
Bryozoan faunas, American Black River and
PRTONGOM YS so ciena <cicisioeisielsioisaiasieresiclaiu=\s/=\2\=s)/> 27

376 INDEX.

Page. Page.
Bythoporaces sceccsseeccccestecceseees eee 178,240 | cingulate, Trematopora.................------ 306
fPUIti COSA a cece eae eae acee cece 240 | Cladopora edilis .............020-000--eeee-ee 242
Subgracilisssasccsss -ccnserecces - 241 | Clathropora flabellaia.................0-.22--- 123
Bythotrypa......+..--- MeeprcooaaSosHeoDSConeS 100 | claveeformis, Dittopora.....................- 302
Calamopora alveolaris..........-...-.-2---02 342 | clava, Lioclemella..................2..200000- 249
Calamopora fibrosd.....-------+--+----- eee 232,313 | claviformis, Leptoirypa.............2-.---.--- 217
Calamopora fibrosa..........0-..0---0s-ecee0 342 | claviformis, Stigmatella...................... 217
Calamopora fibrosa tuberosa ramosa.....---.-- 342 | Clitambonites bed, Bryozoa of..............- 31
Calamopora polymorpha..............-.-.--- 342 | (Coploclema..-.. 2-65. cock cccetecceseedececden 83
Toticulata....-2-..-00decccesense 343 crassimurale ..........---....2--.- 84
COMO DOK e eens tees oe aeeisetaeed ene neee 312,325 laciniatus':-22scsscss2ssseer eee
Calloporaamplac: sane =< 2- =e qeeeeeee 829 | Cenites laciniatus...........2.222--20-eeceee- 85
GUMGLIS Sosa Neeaessics coe eee ee 331 | colliculata, Dittopora........................ 306
ClEGANEUT A. coc cece cececcccneneeess 326,334 | colliculata, Trematopora..............-------- 306
POONEI sao she iE in ae le eee See 214 | collifera, Dianulites.....................--..- 239
goodhwensis.......-.-.--c0eecesceees 327 | communis, Esthoniopora.............-..-.. 259,260

RCEETOSOLEN Soe SoBe es ecco 317 | Composite geologic section, Ordovician of

Callopora ligniformis.......-...-.-.-.---.-.- 343 northeastern Iowa and southeastern Min-
Callopora multitabulata...........----------- 326 MESO oc oeadoasoscossoLsensoesacorsecces 25

NONG eee ceese anne sone cee eee 334 | Composite section, Cambrian-Early-Silurian
NUMMiforMis....-.------+-+------- 335 strata of Baltic Russia................ sae 9
Callopora piriformis .........--.--.--------.. 343 | compressa, Petalotrypa..................---- 266
pUNCtatas.- 22 -soseeensee sone ste 246 | concentrica, Lichenalia....................... 168
Callopora undulata........--.-------+----0--- 332 | conjunctus, Arthrostylus..................... 147
Calloporellatss eens asasceigese oe ociae Seen 78) Constellariaes.-s.-em sees ese ae eee eee 178, 218
Calloporina: $255 eau Nees e eens cco te tegen 178 WADIA ios (eine asc(c aise see see 219
Cambrian and Ordovician formations in Constellariide:. -- 220.2 --2-5- secon eee eee 178, 218
Russia; Tablelofe. ce. seceneseeeee eee eeeeee 6 | constellata, Ceriopora.....................--- 219
Cambrian and Ordovician strata, Table of... 7,8 Stellipora.-<-..¢22222-5.c eee 223
Cambrian-Early Silurian strata of Baltic consueta, Nematopora...................--.- 155
Russia, Composite section of....-...-.....- 9 | Correlations, stratigraphic....-.-............. 36
Cambrian strata, blue clay and associated Corymotrypa: sos.) aesieacoo one eee eee eere 61
rocks; pA Temes 352 ce 10 abruptay..5.5. seseese sete eee 65
Bryozoa in ............-.. 10 barbert:. 2.2552. See 63
description of ..........-- 8 delicatula :::: 225. .-2us25sasceee 61
Ungulite sandstone, A 2.. 10 dissimilis 2.22. 222222 4558--eeeeee 68
Cephalopoda, List of............-.----------- 21 inflate <2 2.cc25yseeek eee eee 64
Ceramopora sii: sceoe enews eee ctonetecneanee 76 schucherti\2.---5-eeeeeeeeee ences 67
imbricatassecn-c accesses WG | Cosentino ooo sc elena e seen sea eee eee 145
intercellata........------.------ 79 CYCIODS <2). so-scstepeuaceeeeeeeee 145
invenusta.....-.--..-.-. Be Seated 78 PESNUNTIUN eee eee eee eee 146
Ceramopora socidlis.....--.-.---------------- 108 | Coscinium proavium........-.--.----------.-- 128
Ceramopora spongiosa....-.---.----------.-- 77 PTOQUUS . 05/05 So s-ceeencaee epee 123
Ceramoporella. 5... csc e eno cesses sce es SL) \Coscinotry pt... oe toes san ae Se Pe 145
Gistineta cease eee eee 81 | crassimurale, Coeloclema................-..-- 84
granulosa minor ..........-..- 81 | crenulata, Stigmatella.......................- 211
uxnormensis .......-.....-.--- 82 || (Crepiporai. - ccs). nce ces cecs see eee ee eee 85
Ceramoporida-cs32 3c ceeanere acne ee Renee 74 | Crepipora impolita..........-.-----.-0--02--- 97
Ceriopora bicornis.........--------=--2---++-+- 317 | Crepipora incrassata.........-..------------- 89
Ceriopora constellata.....-.-.-.------------- 219 lunatifera:....2 25-2 23. 32s sense 88
Gheetetesianniulatusesssa2- eee eee eee eae 304 schmidti o.oo. 2.2 ech ses See 87
ODICUIIEUS 50 hoe a Reese 344 simulans 22s scschecce eee eae ih BO
hemisphericus...--.---------------- 253 | cribrosa, Homotrypella.............-.-.-..-- 192
heberosolet. ...2-2 022 - ose cencceene cote 317 | cribrosa, Stictoporella.............-.---------- 123
petropolitanus......-.---.---+----- 232,313 | cribrosa, Stictoporella...................-..-- 128
DUPIPO MIS 2j2 a= <)w season -h-\els foresee 343 | Crisinella wilensis............--.--+---2------ 73
Cheetetes rhombicus............-.----------- 92 | Cryptostomata..............----------.------ 112
Chasmatoporas <5. seco sence ee eseiss secs 169 | Ctenodonta bed, Bryozoa of.................. 29
TUTCAtas eS sae Sioa scaee se aes Av | (Ctenostomata....5.50252e-0-2-sesseeee eee 54
reticulata see cess seis 170 | cumulata, Monotrypa ( Chaetetes)............- 232
Geuella see jasaseocseerccesesee 169 | curvata, Esthoniopora...........-....-.....- 263
Cheilotnyptrmens casein -e eee eee nsecicee 111 Homotrypa.........-..---------20-- 185
Chilotrypaesssac i. ciiissaiae nee isceeace ae: 111 | cyclops, Coscinium...............----seeeee-- 145
hispid alse s-r22) ge esciee eetas melee sete 111 | Cyclostomata................--- see ube eae 58
IMMAtUIS 2. o5 etc ence ceeesis 111 | cyclostomoides, Micropora........-.-.-.------- 141
cinctosum, Mitoclema.........-......--...-.- 69 | cyclostomoides, Pachydictysa..... SashonEnaon 141
cingulota nodosa, Trematopord.........------- 306 | Cyphotrypa...-.ccc.-ccccccccccccccccsecceces 178

INDEX. 377
Page. Page.
eystata, Trematopora.....-..-----0-e--cse-- 271 | Early Paleozoic Bryozoa, collections of....... 3
Cystodictyonide...... scoogeasosascoososesscs 145 distribution of..... 3,4
dagoensis, Monticulipora............-..-.---- 181 | Early Silurian strata, description of.......... 11
Mekavellasesersese crete es csi sisiswaeesceesen 178,205 | Echinodermata, List of................-..... 19
OUSCUPAscs es see oasis cre cuvette cues 205 | Echinospherites limestone, C 1............... 13
PESNUMGAS soos ns os ot eeeciscieme 2058 | RELeHa yy MESOULY Dane a =< aa ee eels ee eet 198
neevigera ............--- 207 | elegans, Pachydictya.............-..--..--.- 138
simplex ..----<ij--c-eene 200 \elegoniuie, Callopora.....-2<2--2es2--+2-=2e>- 334
ABV OA alte siceic vlcicteis sialeiels cisic ls steisie s\eisienlsine since 178 | elegantula, Hallopora........ Usswameeoenoeees 334
delicatula, Corynotrypa...........-----.----- 61 | ensiformis, Phenopora..............--.----- 118
delicatula, Hippothod.......-...---++--------- Gla PE atalophoride te sac.cesosee sees sete ese eee 69
INEMALODOTO acnuceeeee ee sence ese 155 | Eopaleozoic deposits, Correlation table of... 38
Stomatopord.......----+-+--+-+---- 61S |; Bridotrypasscsccuce acichecnseseuscceeaas oe 178, 242
tenuissima, Stomatopora........-.- 61 eedilisSe-e.522 daceec Sse eos aneee 242
EDD ILM CSONONE ses aca ~ os ols sieletis sesicieciaiws ee eicic/=< 83 MINOTsec ss sae ese ee ee 245
Diamesopora vaupeli........-.---..---.----- 83 Oxigase ase cneec eon ee sete 245
Dianulises... << ---200-e-0- 2 SBS OACBOSEOOCC 178,226 | Hridotrypa mutabilis............---.--------- 2
ENICUIALUS ceoee ana aciacie cise wieae 344 ValsMinonecene aeeeee aoe 245
DiCOnNIS sae seeissec esse se se ciceiese BHU I) PERU OGR Ga coobocoucbocaduscnoceasoLens 133
Dianulites collifera..s...-..2...-20--+--s0ee- 239 Plabellindc ese c8 eee eee 140
fashiciatusees-sseeee ssc see ees 228, 229 GTOCIS eae, CF SE ee eee oe 130
STAN GISS Selsey eee ce siciwalesis 237 Thombicas et so2 os eee ne eee 345
hay. dent. seacescheese tase hee 344 | Eschara scalpelliformis...............-.----- 348
petropolitana..........-.--------- 232 | Escharipora recta........- ao BORea ect ean 345
petropolitanus............-.------ BIST NL SChaNO PCa. mse cess ace cee eee eee 113
Dianulites petropolitanus var. heraporites....- Doo Nt WESCHATOPOLAssses se ee esc eaee eer cet eee see 115
DUNU ONTIUES a ia ctavaraiafaletaiaic sins) staiaisee one 343 recta -Scwss see w eee. SO ae 115
THOMOICUNES << 0% /na cselccistelesin cies 1-1 92 Subrectase cece eee ene eee 116
Dianwlites|sulcatus.-<.-----'-<ceeinnce eee s 344 | Esthoniopora..................-.-..------- 178, 259
DIASLOPOTIGZ socce eels sine eeisis ase rioeeiseeeioee 59 COMMUNIS =e eee eee eee 259, 260
dichotoma, Stomatopora..........-.--.------ 59 Curvatas. soo seeeseeesscnes oes 263
Dictyonema beds, A 3..........--.------.-- DU exiguay bride thy pas-ssseseee cease eeeeseseee 245
DUdYMO POT Ossie se = 1s<isisise sont ie sisseeeeecees 109 Protocrisina tessa. ae -e seater ae aes 72,73
Gifiusa;, RetepOra siecle c seicisaicistaicte toniee ise 1/Zeexalisueeteropolass-eaeaee teeta ee eee eee ee 347
DiplotryPae--- = ose sosreee ee seeceeeie ae 178,312 | expansa baltica, Orbignyella.............-... 183
ID GODT UI CSRS Sac Oe OB RaCeEeer cen ore etiec 196 Orbignyellateeeeeceseeeeeeeee ee oeee 183
Diplomypa bicormiss<. 2 ~~ sess eee ee 317 Ptilodictyarinst.. see eeeec ae seee 114
Hennig esssi se sce seeeaeee eee 322 | explanata, Pheenopora...............-.-.--- 118
AMIPA Ae saiialaia wiaisielsimcicteleretse = aisia 196 | expressa, Mesotrypa..........-..-----.------ 200
limitariss 325 -./0 she eeseeees se Bie I) CANCE JASE), cocecsbecocboctascoocoue Acoce 133
moniliformis...........-...----.- 321 | exserta, Favositella................-..---.--- 102
HGH (he a5 qnepddecs ocaocaseoneas 321 iRhinidictya-cs--seeee sete eee eee eeeee 133
petropolitana..........---.-.-- 232,313 | erserta, Stictopora.........-...--------------- 133
WeStOMI Sao) s sete tse se 323 | facula, Sceptropora......-...-.-.---------- 152, 153
discoidalis, Favositella................-...-.- 103 | fastigiata, Millepora............-.------------ 346
discoidea;, Mesotrypa-. => ---eeeeeece c= oe 196 Myriapora sa.o2 se 522 ee eee 346
orientalis, Mesotrypa......-.-.---- 196 | fastigiatus, Dianulites.................---- 228, 229
dissimilis, Corynotrypa.......-..--.--.--.--- 68 Myriolithes...................--- 346
dissimilis, Stomatopora.......---------------- 68 | Faunas, Russian Ordovician, Lists of....... 19
disticha, Glauconome.............-..--..---- 160')| ‘Havositellasso.s3ocscscosud eee eee 100
STLCN en GLOUCOMOIN Cama eenieaena aaa eee 347 discoidalissoyssssca2sssseeee ene 103
Misticha, bliloporacsssece-sce=ec as ease seeeee 347 OxSOrta cys 2 ic SR see 102
distincta, Ceramoporella............-..-.---- 81 interpunctacsosc-eeeeee ene eases 101
Orbipora-- 3325-2 -sesessecee sees 252, 253 ? punctata......---..--.--------- 105
distinctus, Orbitulites......-..---+----------- 253 | Favosites hemisphericus.......-..-.---------- 253
Dithopora oo 2652 ss acnaseser esa aeese sees 178, 301 hemisphericum.....-..----------- 232, 313
ADUU ALAS cos ose cine ese oa 304 petropolitanus........---------- o. 232,313
claweetormis-2 35. s ee eeeee eee B02 Menestellay: soe. 25. S522 eee 175
colliculataz-s ences ccen see ees 306 striolatay ..icc < ass cee ee se = 175
divaricata, Helopora............-. atest | 449) ||) “Menestellidze sci. snecccneasseenene essence cas 175
DIY MOM DE 2a cases a 3 2s cenee see e ee eae U2.) Menestrellais.ccsczececcsose coset seeeeee coon
CU TETEEIED, OGULG ITE Re RR DEO CUBES SUSeE COLE CES 331 | fertile, Batostoma.........-.----------..---- 274
aimalisEalloporacs echo nase seaeeee sees 331 | fertile circulare, Batostoma..............-.-- 275
PI jOOWSKse eee ccse see cne Se Aa ete Kk 109 | fibrosa, Calamopora..........-.------------ 232, 313
ET UOUSHIEN Cae ase seis aisa ee ae eee ase 109 | fibrosa, Calamopora.............-.--2-2---- 342
dybowskii, Hallopora?............-----0- --- 9385 | fibrosa tuberosa ramosa, Calamopora......-..- 342

378 INDEX.
Page. Page.
Fistulipora js sacssoslGes eee Bee ee 109 | Halloporidae.................2022-222-20- 178,324
PREM BVAL Sac sek Ue teceeeeet ss 109 | haydeni, Dianulites.................-..-.... 344
Fisiulinorella: 25252 Se a sees sooo ee ese 109 | Helopora..........- idee bh aN eee 149
Wistuliporidss 22; << laksa eaee eee 108 divaricatass 2.1.22) 53:2433 eee 149
flabellaris, Phyllodictya............--.---.-- 135 Prapiliss 552555 4:4 552.5 eee 149
flabellata, Clathropora.......-.--------------- 123 | Helopora lineata......-- 22252525222 s02 sees 158
flabellata, Ptilodictya..........-.-.-..------ 114 SUTIGOSD. <0 22555 Dee 2c Soe eee 161
flabellata, Stictoporella........----.---+------- 123 | Helopora tenuis..........-.---------------2< 147
Pilabelliporinags aac = 22 ose eee eee eee 175 | Hemiphragma...........-....--.---------- 178,281
flabellum, E'schara..........----------------- 140 batherk: - .c525/. 52 296
flabellum, Pachydictya..........--.--------- 140 glabrum.;22: 22222222 soseee eee 287
flabellum, Stictopora.........-.-------------- 140 rrastm =.) 2. 2 eee 284
flexuosa, Ptilodictya........-.-..-.--------- 127 maculatum................... 295
Flustra lanceolata. ..............------------ 113 multiporatum...............- 290
folium, Petalotrypa........-.-...----------- 266 ottawaense....._........_.__. 236
food Galloporass 6-4-2441 Bees eee 214 panderi....-. 2 eee 236
foordii, Stigmatella..........-.-...---------- 214 pysmaum. ae 289
fragilis, Helopora..............-------------- 149 rotundatum.................. 294
Nematopora.............----0-2+--- 157 subsphericum............-..- 292
francisca, Sceptropora..........------------- 154 tenuimurale.................. 282
frondosa, Phyllodictya..-.......-..---------- 135 | hemisphexricus, Chetetes................------ 253
fruticosa, Bythopora......-....------------- 240 Pavosites. 23 eee 253
fungiformis, Hexaporites...........----------- 232 | hemispherica, Millepora.......-..-.-.----.- 232,313
fungiformis, Orbipora..........------------- 346 | hemisphericum, Favosites..........--.--.--- 232,313
furcata, Chasmatopora.........-------------- 171 | hennigi, Diplotrypa...................-.--.- 322
PUTCO Poly Mong oes eee sae eee a eee Vl || ieterodictya: Si) eee 113
Fusispira and Nematopora beds, Bryozoa of. 31) jp teieteromem a so 25.55\-y-<is sass Se eee 57
Gastropoda tistiofee. 56 eer eres ee 21 PrISCUM 2555502505 See eee 10,57
germana, Orbignyella.............---.------ 182 | Heteropora gibbosa........-........--.-.---- 224
gibbosa, Heteropora..........-..------------ 224 | heterosolen, Callopora......-.-----.-------.-- 317
Nicholsonella........-.------------- 224 Chittetes. « .222<53o a eee 317
glabrum, Hemiphragma...........---------- 287 Monticulipora.......-..----.---.- 317
gladiola, Ptilodictya...........--..---------- 114 |) Hieterotry pa. sce. 55 ote asa eeoeeeemes 178
Glauconite limestone, B 2..........-.-.-.--- 12 1) (leterotrypides aoa 3-- ee 204
Sandstone, Buh s eter cae eee see 11 | hexagonalis, Leptotrypa........---.-..--- --- 208
Glauconome - 262 S55 2ce aes soae eee ete ens 159) jl Mera nonies ss. cos.4_ ost sete 226, 232
Gistichas kk. = eee eee 160 Fungiformis... 3755-2) ee eee 232
Glauconome disticha........-...-------------- 347 | Hippothoa delicatula..........--.-.---------- 61
Glauconome plumula.........-..------------ 160 INlOtO. onic naeiowissomn a Sone nee 64
SUs0sas sess 32h 255. Seas 161 | hispida, Chilotrypa................-.-..---.- 111
goodhuensis, Callopora...-------------------- 32%) ||) FELOMOELYPa----5 see see eee eee eee -.-- 177,184
goodhuensis, Hallopora ............--------- 327 CULVabae ccc ce eee Seer eee eee 185
Gorgonia'antiqua:.3-4..-4- s44.ss eee ee 175 similis. 2 5..2:46e see ee eee 185
Gorgonia proavus....---.----------------+--+ 123 SUbDramMosas-\os ee eee eee 187
Qnacilis: FSChatG=2 222.2 =p ana = Soseee eee 130) || lomotrypella-..-- 5-22-42 --0 see se 177,189
Miero pond: <2 2 a5. Saco ee eee 130 cribrosa- 25.0. eos s eee eee 192
gracilis, Nematotrypa....-.--.------------ 164,165 hospitalis crassa. --....------- 193
grandis, Dianulites..........-...------------ 237 instabilis. ...2s1 59292 eee 189
granulosa minor, Ceramoporella.....--..-..-- 81 | Homotrypella? subgracilis........-.-.-------- 241
granulosum, Batostoma...........---------- 280 | hospitalis crassa, Homotrypella............-. 193
Graptodictya:cn. = 2326554 eee nee 121° |) RdiotryPassa--ecewaccwiecceemee ct sae eee Eee 178
bonnemaie 22s ses seer e eee eee 122 |) Tdmoneidss. 22:25. ctor ce winieee ieee eee 71
obliquas..2.,- 905: See 126 | imbricata, Ceramopora...........-..-------- 76
perelegans..........--------- 121,122 | immatura, Chilotrypa...............-------- 1l1
PTOAV AL <c 20232 s eee eee 123 | implicata, Monticulipora (Heterotrypa)...-.- 272
PHallOpora seins eae nisps smi peee eiaaeeenaee 178,325 | impolita, Anolotichia.................------- 97
dumalis: 535 222 4ateee nse eee 331 | impolita, Crepipora......-..----------------- 97
Hallopora? dybowskii.............-.-.---.-- 835 | incrassata, Crepipora........-.-------------- 89
elegantilate pase seee eee eae 334 | indenta, Orbipora...........-.-.------------ 257
goodhuensis 222223. sence ees 327 | infida, Diplotrypa............-.---.--------- 196
. multitabulata---_.------ 2-4... 5-4-6 326 | inflata, Corynotrypa..........--.-.---------- 64
splendens: 2.322 525:5.Reeeeeceeee 329 | inflata, Hippothoa..........------.----------- 64
Hallopora? tenuispinosa.............-....... 338 Stomatopord:- <2 s.cccowe ewe asee eee ee 64
LON tee. Sas aceeeereeeee eee 333 | inflecta, Stigmatella...........--.--.-------- 212
undulata... 0224-5. aegis 332 | instabilis, Homotrypella..-.........---.------ 189
wesenbergiana.................... B28 || Untegratare.-csccens-ce seme eee eee eee 178, 265

INDEX, 379

, Page. Page.
intercellata, Ceramoporella.......--.-.------ 79 | milleporacea, Mesotrypa.....---...---------- 201
interpuncta, Favositella..............-.----- 101 | milleporacea-parva, Mesotrypa......---.---- 203
MMECESPACe see aeeee eco = selsei nie! 5 5 ieee Aja piininia) We plOtnypaess=---hene see ease anes 207
interstincta, Stictoporella............-.------ 2 7ia TIITCO Nn SLO NILELO DP OTC see eee eee ee 68
EETICOTLE ee Seis noes es 2 esis eee 169 | mirabile, Anaphragma..........-.--.----- 297, 298
Tein C710 PXTCLLCULOLE 0,2 210 om \=)si=9 inl= = = earl IZ@) || wituwore teint E ooanee cee oneosnceseboesnanonace 69
invenusta, Ceramopora......--..--.--------- 78 borealeAe. 62 sucess eos aoa 69
TESCO ES GLOSLO MUO xine. 21= le = 1 = aioli 284 CINCLOSUME Ss jee eter ee aes 69
irrasum, Hemiphragma.......-...-.-.------- 284 | Mitoclema? mundulum.................-...- 70
iferbedS Csi see eee e or ep sieitetyoss acer 15 | moniliformis, Diplotrypa..........---..----- 321
Jewe limestone, D 1...........---...--------- IBS. |) MOR OWN AS ene penessaseeaesee ‘cee ce nas neq 178, 309
jewensis, Monotrypa.......-...-------------- 310 | Monotrypa ( Chaetetes?) cumulata.....----.-- 232
Kerell beds vue scee es eeett ek eee pone 15 | Monotrypa jewensis..........-..------------ 310
kuckersiana, Trematopora......-.---.------- 270 ; und albalsee eee 310
IKeuckersishale:© 2iois i aoe ees ee es erase 14 ieMonotrypellac.:o24cgcsce.jsteoccasesete cise 178
laciniatus, Coeloclema........-...-.--------- 85 | Monotrypella multitabulata.......--.-------- - 3826
laciniatus, Coenites...........---------------- Son eMonticnliporas-s=—sesse eee see eee 177, 179, 325
Lake Nipissing, Ontario, Islands of, Black WORUG- YOURE EHO ooo baaskcccss sane sesscacc 242
FRVIVELAOSSIIS FROMM eee see toe sete ieee eee 33 | Monticulipora arborea...-....-....-.-------- 179
lamella, Archeopora..-.---------++----+<2-+= 340 bispinulata -..2-.---.- 179
lamellosa, Monticulipora........-.-.-.------- 182 GagOensis seayemiqcsie ees sees eee 181
Ranceolata, Mlustrae .< -ec-eecice ties -seeienc 113 | Monticulipora (Diplotrypa) petropolitana....- 313
lanceolata, Ptilodictya........-.-------------- 114 WAMOSNT Bacocacdaswabsconsetc 317
Leioclema....--. en abies as aceasta aCe 246 | Monticulipora (Heterotrypa) implicata. ..-.- 272
Me DLOUGyDaee sacs 5 2a Nee seeciseeiettse =< 178, 207 Jamellosaaseeaes asijsceee ec Ses 182
Leptotrypa claviformis ........--------------- 217 mammiulatas.242.22:-2----- 179
Leptotrypa hexagonalis.........-.--.------- 208 OVULUM ce o8 races eo ee 346
hI MILI eee Bk s Moeto se a aROse es 207 | Monticulipora petropolitana...........-.--- 232, 313

rchen alliage. 22 2A yk tee ee coe Mere 166 | Monticulipora (Prasopora) selwynii var.

COnceniniCate ese ease eee ae eeee 168 hOspitalis-. 5. seek ccisaeaehen -cewascceeuee 193
ligniformis, Callopora..........-.------------ 343 | Monticulipora wesenbergiana..........--.---- 328
MTbaris. Diplobeywancesccs-eee eases eee S75 eMonticuliporid sess eeseeeeeeeee eee ese sees 177, 178
PATEL PHL CLO DONE 2 soe oe eee ss Nee 158 | multiporatum, Hemiphragma.............-.. 290
lineata incepta, Spatiopora.......-.-.------- 107 | multitabulata, Callopora..............--.----- 326
IN@MatTOMOTA) Soe sasioweetectentee ees 158 | multitabulata, Hallopora..................-- 326
WiOGIEM Ay aac ee eect einai 178, 246 | multitabulata, Monotrypella...........-.----- 326
SDINCUINS joc Seca se eeeeeeen = = 248 | mundulum, Mitoclema?..........-.-.-.-.-.- 70
SVE LUISHULTD. Sacer cea ciate a 247 | mutabilis, Eridotrypa............------------ 242
Heioclemelan eee oss pac sitiae oo /seyeeicieialers aie ere 178, 249 | mutabilis var. minor, Eridotrypa.....--.----- 245
ClaVere. Be cen eee eee eects 249 | mutabilis var. minor, Stictopora.........-.--- 132
NE CITA ATOM er series ae cin eR ne a oe eek ae ASE riba tlismEy hin dc hy aeeeee ease eee eee 132
lunatifera, Crepipora............-.--.------- 88) anutabilis, Sticto pond. «6.222 + eee ae te aee 132
Lyckholm limestone, F 1..........--.-.----. 16 | Myriapora fastigiata...........-..-..-------- 346
MAGI ase terafeteic ce ntle ease wine alee apie Maps sete cis escrces Alia aMiyri OMtHeS He se ee be ea sre sicleyele cree 345
maculatum, Hemiphragma.............-...- 295 Tastigiatuse sess eae se eciaee 346
magnopora, Batostoma...........--.-------. PUP |) TOGO (COTO VO Res cbs saa] eeeaT cc aoeboe coeeSe 334
mammulata, Monticulipora..............---. 179 | neglecta, Diplotrypa......-....-......-..---- 321
Map of Baltic Sea area..............-.-..--.- On| MNEMaAtoOpOratns 242-122 = Jace asejoe ee +s 155
massalis, Stigmatella.......--5..--------.-.- 211 Consueta tes) ce eeoscecsecce s 155
megastoma, Vincularia.......-...--.--..-... 348 | Nematopora delicatula.......-......---------- 155
MWESGIUES a pet eoocosasesoboe susaeeessueeHneS 7 | Nematopora fragilis....... segoaseuecabecaese 157
IMeSO RY Dawes eee oe cance ee seas aoe 177, 196 NMOS Laie arse ele aa eee oe ey 158
discoideas- teases tenes eine 196 Ovalisz ice eec nt ceneeneeeseee 155, 156
ovientaliseeee-ssaee--e 196 | Nematopora quadrata...........-.-.--------- 156
CP ONO Aya siesta es yore 198 SENIGOSU es Sas ee Rees aE a 161
GEGOMESSE Seco sossdoosscoesoececens ANY): || IN(STMIRIOUE Ne costo eked sesscnossdasaqecacas 164
mille pOracea 5 f= s-<\ seiee = els) -feriale 201 PTACUHIS Mes poy we eee 164, 165
PanVia se cose 2039 Nicholsonellaste=se ess s--eseeeseeeeesee ee 178, 224
mMickwitzi,, BatostOMa. 2200 = clo-sice s-cie vee 276 gD OSAL eas. fe acice Somes ances 224
BVILCTO DOT rset ao css oe Seals Pe ee ache aoe 127, 345 PONderOSa au ssee ee eee 224
CUCIOSLOTILONIES Se = een reise alee 141 | nicholsoni, Rhinidictya.............-.......- 132
GUC Sos Ee coe aman aetna 130 | North Polar region, Map of...............-.. 40
SOMUDICH = oe 2 vies aeetals yet Si 116,345 | North Polar seas, Bathymetric chart of..-.- 44
ME EBON DICULUL Caen nee eee eee 344 | nummiformis, Callopora............-.-.--.-- 335
SRSTAG UAL apes sey ek apn ete e120 346 | obliqua, Graptodictya...................---- 126
hemispherica.........--------+--- 232,313 | obliquus, Arthrostylus..............-------- 148

92602°—Bull. 77—11——26

380 INDEX.

Page. Page.
obscura, Dekayella.......2-.-0------------- 205 | petropolitanus, Chextetes.........-..-.------ 232,313
oeilensis, Crisinella.......----.--------------- 73 | petropolitanus, Dianulites...............---- 313
Oldest known Bryozoa.......----.---+------ 3,10 | petropolitanus, Favosites..........-...-.--- 232, 313
Orbienyellaeeeeeeeseeeee eet eeeeaeee ee 177,181 | petropolitanus, var. hexaporites, Dianulites.... 232
OkpPansasisas Nee aeeeence. $83) Phaenoporatse. eee ence ele 118
balticasseceecean seeece= 183 | Phaenopora cf. ensiformis..........-.-.------ 118
COUN sococoeaaae aan aceodosess 182 | Phaenopora explanata.................------ 118
sublamellosa............-.------ 1825) Phyllodictyaysenee- eee eee eee ee eee eee 135
BNET POLS eee RIE Se ee es FN 178, 251 Aabellaniss ee eee 135
acanthophora......-.-------------- 255 fromdosa gic. ced cslaeee oases 135
Gistinetan eet Aes ae 252, 253 Varlaeeeecseeens @ 2 7 ae 136
fonciformisss so se se ee eee eee 346. || Phylloporina...... 25-220. ee ee eee 169
TAG (0) EH Aa aR Se ae Bae 257 | Phylloporina and Fucoid beds, Bryozoa of... 30
Orbipora panderi.......---------------------- 286 | Phylloporina reticulata..........--.-.-------- 170
Orpiporajsoldatesseseer eee eeee ss eeee eee 255 | Phylloporinidz....5........-.-2---------256 168
ORDItUT ites ee ee ee ne ee see 251 | piriformis, Callopora..........--.------------ 343
(PICU Roos acncace ase cacosesscse5 344 Cheetetes. Sy.iee. 3 eee 343
Cistinetuseeee eee eee ee eee 253 | piriformis, Dianulites...........------------- 343

Ordovician formations, Upper Mississippi Platteville limestone in Minnesota, Bryozoa
WE Ene sdcads roseeeecnceded Sesosanesnesasoc 25 Ola fees Ba 28
Ordovician of northeastern Iowa and south- plumula, Glauconome...........-.-.-..----- 160
eastern Minnesota, Composite geologic sec- polymorpha, Calamopora........-.-...------ 342
THOT haan acannbeocosoussbasdacsensa5o5050e 250i POLY POOL COL eee eee ee eee eee 171
Ordovician strata, description of ....-..-..-.- 11 | ponderosa, Anolotichia...............-..--.- 91
Dictyonema beds, A 3..-.. 11 Nicholsonella...........-.------- 224
Echinospherites limestone, preenuntia, Dekayella...............-.------ 205
CL eee eae Seale 13 neevigera, Dekayella.......-...-- 207
Glauconite limestone, B 2. 12 simplex, Dekayella........-...-- 207
Glauconite sandstone, B 5. 11 | prenuntium, Coscinium.................-.-- 146
Itfer beds, C3.......-.--- 1555] (erasOporajyaace ene ee ds." eee ee eee 177
Jewe limestone, D1-...-.- 15 | primeeva, Fistulipora.....-..-..--..--.------ 109
Kegel beds, D 2..-...-..-.- 15 | primigenia, Trematopora..........-.-------- 268
Kuckers shale, C 2....---- 14 | priseum, Heteronema............--...------- 10, 57
Lyckholm limestone, F1.. 16 | proava, Graptodictya..........-...---------- 123
Wassalem beds, D 3....-- 15 | proaviwm, Coscinium......------------------ 123
Wesenberg limestone, E.- 16 | proavus, Cosciniwm......-.--------------- 5 eds
erosa, Pseudohornera.......------.---------- 174 i Gorgoniteeee nee ee eee eee ee eee 123
orosus, Thammiscus.....--------------------- 174 | Protocrisina........------------------------- 71
Orthoceras limestone, B 3...-....----------- 13 @xi guesses sess aaa eee 72,73
Ostracoda, List of.....-- Us arn es RN Hess 22 ulnichi sao sss so sce ee 73
ottawaense, Hemiphragma...-...----------- 286 | proutana, Stomatopora.....------------------ 61
ovalis, Nematopora.....------------------- 155,156 | Pseudohornera......-.-------------- Aaa 172
ovulum, Monticulipora........-.------------- 346 bifidass 23.2: 2 eee 173
Pachydictya....-...--------++-----+---+---++- 137 Onesaie ae .e seca eee eee 174
bifuncatawas sare cesses eens ee 143 | Pteropoda, List of.....-..-.----------------- 21
cyclostomoides........-..------ 141 | Pteropora.....-.-.----------+-+---2+2+2---- 347
elegans. Wu) dado eee 2 eae 8 @xilisy a yee he Bes ae eae 347
Mabellumys sys ssa sae se es 140 pennularte sees eee ee eee 347
FODUStAE Ee eee nese eee 138 | Ptilodictya-.....--.-------------------++---- 113
Paleogeographic map, Generalized........--- 43 @XANSAS ese sna eee ee eee 114
panderi, Hemiphragma.......-..-.-------.-- 286 flabellatasessssessse = =e eee eee 114
panderi, Orbipora.......--------------------- 286 flexw0saesss fees ene e ee eee 127
Pelecypoda, List of......-.-..--------------- 21 ladiolaee eee ae = ets er alent 114
Penniretepora......-.------------------------ 159 | Ptilodictya lanceolata.....-------------------- 114
pennula, Pteropora........--.--------------- 847 | Ptilodictya subrecta..--..---------.--+--++++ 116
perelegans, Graptodictya.....-.--.-------- 121,122 | Ptilodictyonide. -.-.------ 7 de eR 113
IPeTOnOPOLA eee see ee ase eee eo 177 | Ptilopora disticha......-.----.--------------- 347
pertenuis, Rhopalonaria....------------------ 61 | Ptychonema....--.--------------++--+++7+---- 309
JEGWAOUE ACE) ose canto esaasosnsoosesasssose 178,265 | Publications, List of..--.--.--------- uh) dees 48
COMPTeSSap eee eee eee eee eae 266 | pulchellum, Arthroclema..-...-.-.----------- 150
NOMI Seas sass adobsossesogacse 266 | punctata, Archeopora..-.-..-.------------- 105, 341
Potigopora. 2.222222. -- 5-2 -.- eee s- 2-2 - = 178 Calloporassses see eee -- eee eee 246
petropolitana, Dianulites..........---------- 232 Mavositellasceaseceeeee eee eee 105
Diplotrypa......--.-------- 232,313 | pustulifera, Trematopora.-.------------------ 306
petropolitana (Diplotrypa) Monticulipora...-- 313 | pygmeeum, Hemiphragma....--------------- 239
Monticulipora.........-------- 232,313 | quadrata, Nematopora..---------------------- 155

INDEX, 381

Page. Page,

radians, Archeopora......-..------------+---- 342 | splendens, Hallopora..............-..--.---- 329
radiata, Scenellopora..........------.--.----- 107 | spongiosa, Ceramopora............-....----- 77
PectaswESChariporac jase essai oe ecemeese BS) || SueI ENON ooo a poseescaeensssoeecoecedacee 178, 221
Hischargporassccice ass csoas sees DD SLL ED ON Wars isrjaiciclsie syaniare- ceca rs emeaerscoaesiece 218

TECLB, SLOMULOPONGs-- 2.0 ----- =~ --0ese see 68 | Stellipora antheloidea........................ 221
TOPCTIS VANE Mare eee cise soso ese secee geese 55 apsendesoidestas.s.-- 22 ee-sscn ene 223,
Rete POLa ANE UIALA Sj ccet we ed ee teeters 169 constellataas i sascce ne eo eee 223
GUUARUIS SEAS so sis aie aC Lae 172 LOVGICNSIS Ss Uae eee ee ees 221

Retepore tenella... cecee- 2m e enn ee eee UGS) || Stage on cee seeopeoasesseeedsenoseccnec 131
reticulata, Calamopora..........-...-..------ 343 | Stictopora bifurcata....-.......-.-----.------- 143
Chasmatopora........-....-------. 170 CLBEN Doom ctase eiiainije eros hes aes eee 133

reticulata, Intricaria?..........-..2.---+-+---- 170 ELUCLLIL INR cme eee ee eens 140
IERUMOPOTENG eee nae eee eee 170 MMULOD UI S see isacireeee sae see cea 132
Suebnelepontoasa sce aasea oe eceeoee 170 UOTNIUTLON A yeasts eee 132
revalensis, Anolotichia........-.........-.-.- 95 | Stictopora (Ptilodictya) shafferi.........:... 119
Stelliporass 2.22 ya) gees 221 scalpelliformis® =-22-2-2--0-ce-esne 348

hab dinopordess.vessccsssancees Lia OO ey 348 | Stictopora scalpellum..........-....--.------. 143
Rhabdomesontide..............- Sis Senn aie TGQMOtictoporella the s-- sso cent etee bees 127
HUN IMI GI Chy asses eco eese he eee eee eens 131 | Stictoporella bed, Bryozoa of................ 28
Rhinidictya bed, Bryozoa of......-....-..-.- 29 | Stictoporella cribrosa.............------------- 123
Rhinidictya? Borkholmiensis..............--.- 143 | Stictoporella cribrosa.............-.-.---..-- 128
RMiMidichyaiexsertaleet sae aos aesss sss s oe eee 133)m | SLICLOpOTELLanLaOClOlaaee sate ee aaa eee ee see 123
MAUIbADMISSs sass Fe = cee seer 1323 | ¢Stictoporellazracilis=e..---2-scesoseneceeese 130
nicholsonig-ccesae: sae eee 132 INteLShINctaces-= see eee eee emer 127

RU NAdichy Omid esse wset eee here eee cea ceer 1 SItn sik Ctoporellid cesses sense eee me eer eet eee 127
Rhinoporide........ SER et along a OC Ueda dGbm ms tigmatellaeeeeanyt seer areas ea esas e ee 178, 210
rhombica, Anolotichia........-.-.....------- 92 Clavalormisis=asaseee eens cess 217
thombica, Eschara..-.......--------- Fsaeees 345 CrentWlatas sc iescess ses aeccceaees 211
rhombica, Micropora........---------.----- 116, 345 MOOR OTe enh eee a Soe cenee 214
thombicum, Dianulites........--.------------- 92 inMeChass-eopck rises eqnde eke kaeene 212
rhombicus, Cheetetes........--------2-------- 92 MASSANS eee ene eae eee 211
EUBOMIPOPOLA=Sevecee sess aceae eee tenses caeee 162) | Stomatoporars.2s- eee sees sceeeonsces scenes eee 209
Esthoniweasjss se eroncteecces NGS} || SUOMMALO OO oes coe seo soonoeasdeosensneedcees 61
lepidodendroides............... 163 | Stomatopora arachnoidea......-............. 60
RuBombotrmyparcsccs <2 sre eae eee 178 | Stomatopora delicatula tenuissima............. 61
Rhopalonaria pertenuis.....--.------2----+--- 61 | Stomatopora dichotoma..................... 59
Richmond group, equivalents of............. 2 | Stomatopora dissimilis.........-..-..-..--.+-- 68
RObustia seach Gichy Avec) aesoe eas 138 SNLOL Ore reioas Stenisoe emcee Sees 64
rotundatum, Hemiphragma.............-.... 294 MAINON= see scenes seca eeeaeee es 68
sacculus, Anolotichia.........-...-...-...-..- 98 DROULEN Macias tie soeeeeees ees 61
scalpelliformis, Eischara.....-.-.-------------- 348 TOCtOeteeminae ee caee a eee ee ae 68
sealpelliformis, Stictopora............-..-.... 348 LONUASSUIMNG os = sso seaee ese ene 61
scalpellum, Stictopora..-....-.....---.---+--- 143 | Stones River Group.......-......---.......- 26
Sconelo pora ew Me sasase sola wen ea secek cue ee 107 | strigosa, Glauconome.............-..-..-.... 161
Badia tae peste ee Ac eae waue 107 | strigosa, Helopora...-...-..--.....-----.+--2- 161

SOGlalis: eee ce ie sees eens DOR NEMALOPON@ 2. 3- seisk wean sss se oe 161

OC DELO POL At soace Sass ome at eee eee ree 152 | striolata, Fenestella.......................... 175
faClaoss est cemes aamate tence 152,153 | Stromatotrypa...........--.----2--2---eece-s 178

IRAN CISCA Rie see eae 154 | subgracilis, Bythopora......................- 241

Seimidti,| CrepipOlac. csa--sec2sess sen sccacee 87 | subgracilis, Homotrypella?..............-...-- 241
schucherti, Corynotrypa.......-............- 67 | sublamellosa, Orbignyella................... 182
selwynii var. hospitalis, Monticulipora (Pras- subramosa, Homotrypa....-.....-..----.---- 187
PROT) bas setae eee etc en ee eon amee tat 193 | subrecta, Escharopora.......-...--..-.-...-. 116
shafferi, Stictopora (Ptilodictya)........-.... 119 | subrecta, Ptilodictya.........-...-..--.---.-.- 116
Silurian strata, Borkhoim limestone.........- AG) Suebrete pong see ie yaaa (hae a ee oon me 169
Lyckholm limestone......... 16 TCLICULILO Soo. a eho oee 170

SHAMS HE OMOLY: PAs. novi Soee nee eiseice sence 185 | subsphericum, Hemiphragma................ 292
SHIP IOX PAT IMTOPOLAs- > necncccecscenccece aces 120 | suleatus, Dianulites.......-.....-...-.2..--.- 344
simulans, Crepipora-..3...0-0.02-s-s2-ee-ne 86. | tenella, Chasmatopora..................-...- 169
ROLL IS mOCTATLODON Macaca. |= /3 55122 ese ee oe LOSt | MECIELLERWI: CLEDORGieceee sense epee eee eee 169
BOCIDUSOCENCMOPOLAS.2.cce se oeceenascseeccne 108 | tenuimurale, Hemiphragma.................. 282
ROU ROL DIPOLAs=ccceho neocon cman eee eet ebee 255 | tenuis, Helopora..................-........-- 147
SUPPLE OT pues ape sa eens hy eyeliner NA 106 | tenuispinosa, Hallopora...................... 338
asperaics ce. so o8 ee Neet TNE: 106 | tenwissima, Stomatopora.................-.--- 61

lineata incepta: = s-=2s2es5se-se2- LOTM || -BRamniscus ifid@= -2s2- ene eee eaenceeee ee 173

SPIMCHIN TL IOCIOM Asc... o20cciscc sce ce stasis one 248 ON OSUS Ce oes ata ec oe rec ae 174

382 INDEX.

Page. Page.

ROM NOCE Asa ne pictmcisseer cites teceee eee 172 | Upper Mississippi Valley, Ordovician forma-
toll; Halloporas)-2)5-42a..c ee eee eee eee 333 tions:of. 2 cca. 555556225. eee 25
MremAtopora. = sacs sce Fasc coesiase eee 178,267 | uwxnormensis, Ceramoporella sau: oe 82
REM ALO POT Ox aia nia saison ee 301 | varia, Constellaria..-...........--.--=--:222.- 219
CUINGULALE 2652S eee 306 Phyllodichy asso: 22-24..--eeeee eee 136
mnodosa...-.--.-.------- 306 | variabilis complanata, Trematopora....-.--.--- 306
COUC UAL ee se ae er So 306 TREMAtOponWe-e ee nce ana eeeeeeee eae 06
Trematopora cystata...-..-...---.--.-------- 271 | vaupeli, Diamesopora.........-...----------- 83
kuckersiangeenc eee es seee 270: | Wiesicular tissue sae ee eee 48
primigeniaes-s eee sess Pee eee 268 | vetustum, Lioclema..................-...-- 247
Trematopora pustulifera.......--.------------ 306 | Vincularia megastoma..........-.-.--------- 348
Trematopora tuberculosa.........-.--------- 268. || Winella toes 23.0 605-2. 5.20.6. eee ee eee 55
Trematopora variabilis.........-.------------- 306 TEPeNS: o 2 jee dbs 55
complanaia..22-..:.=..\' (806! Wanellidee. cee. sn so eee ne a eee eee 55
rematoporidcess.csceecee sane eece enone 178,267 | Wassalem beds, D 3...............----------- 15
Mrepostomatas sak. .25 assess eases hse 176 | wesenbergiana, Hallopora.........-.--------- 328
MrilobitasshAstiofessassasaasc-eee ee eee eee 23 | wesenbergiana, Monticulipora..........-..----. 328
tuberculosa, Trematopora.........-.....-..-.- 268 | Wesenberg limestone, E..........--.-------- 16
ilrichi, Protocrising-- 22-2242 222532222 o eee 73 | winchelli, Amplexopora.........-.--.--------- 278
undulata, Callopora........---.-------------- 332 | winchelli, Batostoma...-...-...-.----------- 278
tindulata selalloporass- sess e eee ee ee 332 spinulosum, Batostoma.-.--.-....-- 279
undulata, Monotrypa......--..-.------------- 810 |) Aoarigm.......622.h2h542- 525. eee eee 46
Ungulite sandstone, A 2.......-...-.----..--- 10 | -Zocecium:. +25 2.52.2 4.4b56 3 eee eee 46

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