(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Redescription of type specimens of species of the bryozoan genera Monticulipora, Mesotrypa, Peronopora, and Prasopora, from the upper Ordovician rocks of Toronto and vicinity, Ontario, Canada"

Life Sciences Contributions 
Royal Ontario Museum 



107 



Redescription of Type Specimens of Species 
of the Bryozoan Genera Monticulipora, 
Mesotrypa, Peronopora, and Prasopora, 
from the Upper Ordovician Rocks of 
Toronto and Vicinity, Ontario, Canada 



Madeleine A. Fritz 



Digitized by the Internet Archive 

in 2011 with funding from 

University of Toronto 



http://www.archive.org/details/redescriptionoftOOfrit 



LIFE SCIENCES CONTRIBUTIONS 
ROYAL ONTARIO MUSEUM 
NUMBER 107 



madeleine a. fritz Redescription of Type Specimens 

of Species of the Bryozoan Genera 
Monticulipora, Mesotrypa, 
Peronopora, and Prasopora, 
from the Upper Ordovician Rocks 
of Toronto and Vicinity, 
Ontario, Canada 



Publication date: 26 April 1976 

ISBN 0-88854-184-8 

Suggested citation: Life Sci. Contr., R. Ont. Mus. 



ROYAL ONTARIO MUSEUM 
PUBLICATIONS IN LIFE SCIENCES 

The Royal Ontario Museum publishes three series in the Life Sciences : 

life sciences contributions, a numbered series of original scientific publica- 
tions, including monographic works. 

life sciences occasional papers, a numbered series of original scientific publi- 
cations, primarily short and usually of taxonomic significance. 

life sciences miscellaneous publications, an unnumbered series of publica- 
tions of varied subject matter and format. 

All manuscripts considered for publication are subject to the scrutiny and 
editorial policies of the Life Sciences Editorial Board, and to review by persons 
outside the Museum staff who are authorities in the particular field involved. 



LIFE SCIENCES EDITORIAL BOARD 

Chairman: Walter m. tovell 
Editor : a. r. emery 
Associate Editor: I. r. ball 
Associate Editor: j. c. barlow 



Madeleine a. fritz is a Research Associate in the Department of Invertebrate 
Palaeontology, Royal Ontario Museum, Toronto, Ontario. 



price: $1.50 

© The Royal Ontario Museum, 1976 

100 Queen's Park, Toronto, Canada 

PRINTED AND BOUND IN CANADA AT THE BRYANT PRESS LIMITED 



Redescription of Type Specimens of Species 
of the Bryozoan Genera Monticulipora, 
Mesotrypa, Peronopora, and Prasopora, 
from the Upper Ordovician Rocks of 
Toronto and Vicinity, Ontario, Canada 



Abstract 

The species Prasopora donensis Parks and Dyer, Peronopora vera 
Nickles and Mesotrypa distincta Parks have been previously 
identified and described from the Upper Ordovician rocks of 
Toronto and vicinity. The sub-species Monticulipora parasitica 
multipora Dyer is herein accorded specific rank. The type speci- 
mens of these species are redescribed using qualitative and quantita- 
tive methods together with improved illustrations. A new species, 
Prasopora richmondensis sp.nov., is described from the same strati- 
graphic horizon. 



Introduction 

The Upper Ordovician rocks that underlie Toronto and vicinity are included in 
the Georgian Bay Formation (Liberty, 1969). Prior to 1969 two formations were 
recognized, namely, Dundas (Parks, 1924) and Meaford (Foerste, 1924). These 
two formations were correlated respectively with the Maysville and Richmond of 
Ohio. The Dundas Formation was divided by Parks (1924) and Dyer (1925) in 
ascending order into the Rosedale, Danforth, Humber and Credit Members; 
the Meaford into Erindale, Streetsville and Meadowvale Members. Parks and 
Dyer (1922) described the Bryozoa of the Dundas Formation; Dyer (1925) 
described the Bryozoa of the Meaford Formation. Armstrong (1945) studied in 
greater detail the genus Stigmatella. Since the descriptions of the above workers 
do not meet present standards, I began a study of the specimens which the authors 
designated as types and which at present are located in the Department of 
Invertebrate Palaeontology in the rom (Fritz, 1970, 1971, 1973, 1975). This study 
has resulted in more detailed qualitative descriptions, in quantitative analyses, 
and in improved illustrations. The present paper deals similarly with the type 
specimens of species of the genera Mesotrypa, Monticulipora, Peronopora, and 
Prasopora. 



Materials and Methods 

The specimens studied in this paper include: 

Mesotrypa distincta Parks, 1925 

Monticulipora parasitica multipora Dyer, 1925 (herein designated M. multipord) 

Peronopora vera Nickles, 1905 

Prasopora donensis Parks and Dyer, 1922 

Prasopora richmondensis sp.no v. 

In addition, the following type specimens have been kindly loaned to me for 
comparison with the rom types: 
Monticulipora multipora Utgaard and Perry, Indiana University, Hypotype No. 

8252 (plus 8 micro sections of this Hypotype, Nos. 1051, 1284, 1388, 1599, 

1645, 1646, 1647, 1648). 
Peronopora vera Ulrich, United States National Museum, Holotype No. 43943. 
Prasopora nodosa Ulrich, United States National Museum, Holotype No. 43691. 

The external features of the zoaria (i.e., shape of the colony, character of the 
surface) were observed with the aid of a hand lens, but the internal structures of 
each species were determined by means of thin sections. While the descriptions 
are two-dimensional, that is, as to what is seen in each of the standard views, 
nevertheless, three-dimensional relationships of the interior of the colonies are, 
to a certain extent, inferred. A study based on three-dimensional relationships is 
outside the purpose of the present research. The mensuration of the number of 
zooecia in 2 mm in the intermonticular areas and measurements in millimetres of 
the maximum dimension of zooecial apertures in the monticular and inter- 
monticular areas were made with the aid of a binocular microscope and a 
micrometer scale calibrated to 0.01 mm. The number of entire mesopores and the 
number of entire acanthopores in 1 mm 2 were obtained by using a compound 
microscope and a reticle calibrated to 1 mm 2 . Statistical computations were made 
on the ibm 370/165 computer at the University of Toronto Computer Centre. 
As most of the samples had heterogeneous variances it was not possible to test 
differences among means using parametric statistical methods. Instead, the 
samples were tested for differences in dispersion using the non-parametric Mann- 
Whitney U-test (Siegel, 1956). In the tables probability ranges associated with 
significance tests are designated with asterisks as follows: *** = P < 0.001; 
** = p < 0.01 ; * = P < 0.1 ; not significant = ns = P > 0.05. 



Systematic Palaeontology 

Order Trepostomata Ulrich, 1882a 
Family Monticuliporidae Nicholson, 1879 

Genus Monticulipora D'Orbigny, 1849 

Description 

Emended description of Monticulipora in Boardman and Utgaard, 1966. 

Type Species 

Monticulipora mammulata D'Orbigny, 1849: 25. 

Monticulipora multipora Dyer, 1925 

Fig. 1a, b 

Monticulipora parasitica multipora Dyer, 1925: 71. 
Monticulipora multipora — Utgaard and Perry, 1964: 43. 

Original Description (Dyer, 1925) 

Two specimens were obtained from the Streetsville member which appear to belong to 
Monticulipora parasitica except for the fact that they possess numerous mesopores. In 
this respect they agree with the form described and figured by Cumings from the Liberty 
of Indiana, as belonging to this species. The apparent identity of our specimens with those 
of Cumings and the constant departure from the type of the species, as indicated by the 
presence of mesopores, seems to justify the creation of a new variety. The new variety 
resembles M. cincinnatiensis, as stated by Cumings, but it differs in having acanthopores 
and in the lower type of monticule. 

Emended Description 

Dyer designated two syntypes, rom 12168 and rom 12169. The following descrip- 
tion of syntype 12168, now the lectotype of M. multipora, adds significantly to 
that of Dyer (1925). Syntype 12169 is another species (to be considered later). 

EXTERNAL FEATURES 

Zoarium an overgrowth on a small dome-shaped mound of sediment and fossil 
debris, 15 mm wide X 10 mm high, at the base of which a fragment of Isotelus 
occurs. Thickness of zoarium 2 mm, surface of zoarium with prominent, conical 
monticules, spaced 2 to 2.5 mm apart measuring from centre to centre. 

TANGENTIAL SECTION 

Zooecia subcircular to circular, 9 to 1 1 in 2 mm (Table 1). Zooecial wall granular, 
knotty in appearance owing to irregular size of granules, 0.01 mm (or less) thick 
below surface; 0.02 mm near surface and up to 0.03 mm in monticules, thin 
zooecial lining, concentrically laminated, best observed near surface. Angular 
mesopores varying in shape and size, from small to one-third size of zooecia, 
surround most zooecia (Table 1). Acanthopores absent. In the wall, minute round 
dots, with lucid centres, represent granules with clear interiors (Ulrich regarded 
these lucid spots as acanthopores). Monticules with small mesopores interspersed 
among zooecia which are larger than the zooecia in intermonticular areas, maxi- 



.23 

■•-> 
cd 

■»-» 

in 
D 

G 
+-> 

• 

d 

c 

cd 



W 

-H 

c 

Cd 

0) 



O 



ON 



ON 



* 

d 



3 rT 

Q r^ o ^ 
o ^o o r- 

© "J - S^© S d S 

-H ^ +1 7 +1 T +| T 

I /"i. °° f^ 



»o oo 



od 



<N 



«n 



1 O 



o 



O 



8 



o 



w 

-H 

c 

cd 



,— I l—l <*J ND 

o 2 H o^ c • o . 
-H 7 +1 ? -H ? 



3 

o ^ 

O NO 



+1 



-L i— i oo m 

O <N >-" <N (-J ,- 1 ' 

d o o w o w 



8 



O 



O 



O 



6 

3 

z 



.s 




CO 

(-1 
<— • 

S3 

o- 

CO 

E 

3 

s 

X 

CO 





Fig. 1 a-b. Monticulipora multipora Dyer, lectotype rom 12168. 

a. Longitudinal section, X48.6 

b. Tangential section, X48.6 



mum zooecial aperture in mm in monticules 0.18-0.26 (Table 1); maximum 
diameter of zooecia in mm in intermonticular areas 0.13 - 0.20 (Table 1). 

LONGITUDINAL SECTION 

Zooecia either subprostrate or erect above base of zoarium, thereafter proceeding 
directly to surface of zoarium. Walls thin throughout, knotty or minutely 
wrinkled, owing to their granular nature, thin zooecial lining best observed in 
younger part of section. Straight diaphragms and overlapping cystiphragms occur 
in zooecia, their arrangement varies from half diaphragms and overlapping 
cystiphragms near the surface to diaphragms only near surface, spaced one to 
one-half tube diameter apart; cystiphragms usually in single series and in the 
older part of zooecium, rarely in double series. Mesopores numerous and with 
close-set diaphragms, commonly spaced one tube diameter apart. Acanthopores 
absent. 

Remarks 

Monticulipora parasitica Ulrich, 1882b and Monticulipora parasitica multipora 
Dyer, 1925 are similar in habit of growth, but in M. parasitica the zooecia are 
angular and the monticules are composed of aggregations of small mesopores 
surrounded by larger zooecia than those that occur in the intermonticular areas ; 
furthermore, few mesopores occur in the intermonticular area. 

Monticulipora epidermata Ulrich and Bassler, 1904 which shows affinities 
with Monticulipora parasitica multipora Dyer, differs in that it forms small, low, 
hemispherical masses to thin plate-like zoaria, which give off branches or knob- 
like protusions; mesopores in inteimonticular areas are few and small, and mostly 
confined to the centres of monticules. 

Utgaard and Perry (1964: 43), although they did not examine Dyer's type, 
identified and described his taxon from specimens collected from the Whitewater 
Formation of eastern Indiana and western Ohio ; they referred to their specimens 
as Monticulipora multipora. I have examined hypotype No. 8252 from Indiana 
University and find that it is very similar to Dyer's type qualitatively. Quantita- 
tively only a slight difference is noted in the maximum aperture diameter of the 
zooecia in the intermonticular areas (Table 1). I therefore agree with Utgaard 
and Perry that Dyer's variety should be given specific rank and known henceforth 
as Monticulipora multipora. 

Locality 

Meaford Formation, Streetsville, Ontario. 

Type 

Lectotype rom 12168. 



Mesotrypa Ulrich, 1893 

Type Species 

Diplotrypa infida Ulrich, 1886. 

Mesotrypa distincta Parks, 1925 

Fig. 2a, b 

Mesotrypa (?) sp.nov., Parks and Dyer, 1922: 5. 
Mesotrypa distincta Parks, 1925: 36. 

Original Descriptions 

Parks and Dyer's 1922 description of Mesotrypa (?) sp.nov. follows: 

Of frequent occurrence on the Humber river is a discoidal bryozoan with a concentrically 
wrinkled epitheca which may attain a diameter of 25 mm. The surface is gently convex 
and practically smooth; the under side is correspondingly concave. The thickness varies, 
and superposition of layers is not uncommon; a single layer is generally about one 
millimetre thick. 

The surface shows, in places, sub-quadrate zooecial openings more or less regularly 
arranged and occurring to the number of nine in the space of two millimetres : in these 
areas the walls seem to be in contact. In other parts of the surface the openings are 
larger, more rounded, and separated by distinct interspaces although the zooecia are 
never completely out of touch with each other. 

Tangential sections show that the walls are moderately thick and independent even 
where the mesopores are absent and the zooecial walls in close contact. Very small 
acanthopores are sparingly developed. Vertical sections show the zooecial tubes to arise 
with a slight slant from the basal plate and to proceed almost directly to the surface 
with walls of practically the same thickness throughout. The zooecial tubes are crossed 
by numerous irregular diaphragms for about two-thirds of their length ; the peripheral 
third seems to be devoid of internal structures. The diaphragms are slanting and irregular 
and occasionally simulate cystiphragms. Between the zooecial tubes are numerous 
mesopores, crossed by close-set, horizontal diaphragms, which continue to the surface. 
These mesopores show distinct evidence, in places, of narrowing towards the surface 
of the polyzoarium. 

Parks' description in 1925 of Mesotrypa distincta follows: 

Numerous and better species of this discoidal bryozoan have been found since Part II 
appeared. The description therein is accurate and needs little addition. Good vertical 
sections show a most distinct pinching-out of the mesopores towards the surface. In 
some cases, however, the mesopores continue to the surface with no diminution in 
diameter. Shallow tangential sections show only occasional mesopores, the point at 
which a mesopore might be expected to appear being occupied by an acanthopore. The 
species is found at various levels on the Humber and abundantly at the Prison Farm 
quarry. 

Emended Description 

Among the type material labelled Mesotrypa distincta, six syntypes are repre- 
sented. The original description was based on only one of the syntypes, now 
designated lectotype rom 1200hr. The remaining specimens were not sectioned 
by Parks and Dyer but sections prepared for the present study verify the accuracy 
of their identification. They become paralectotypes. 



EXTERNAL FEATURES 

Zoarium free, hemispherical, diameter 15 to 17 mm, 1.5 mm thick, slightly convex 
above, base correspondingly concave with concentrically wrinkled epitheca; 
surface with maculae flush with surface, normally 2.5 mm apart measuring from 
centre to centre and consisting of zooecia larger than those in the intermacular 
areas. 

TANGENTIAL SECTION 

Zooecia angular to subangular near surface, subcircular to circular below surface, 
shape depending on number of mesopores present at a given depth, eight to nine 
zooecia in intermacular areas (Table 2). Zooecial walls uniformly thin 0.01 mm in 
general, 0.02 mm in maculae, concentrically laminated, laminae very fine, dis- 
tinguishable best under magnification of X250; where two zooecia in contact a 
dark area present formed from the combined laminae of the adjacent pair. Meso- 
pores numerous in 1 mm 2 (Table 2) mostly rectangular, or triangular, more 
numerous and larger at depth where they may surround zooecia in one or 
two rows thus rendering zooecia circular to subcircular; mesopores become 
smaller towards surface and at times peter out, leaving dense tips which might 
suggest acanthopores, here zooecia become subangular to angular. Acanthopores 
absent. Maculae composed of larger zooecia than those in intermacular areas, 
some with large mesopores. Maximum apertural diameter of zooecia in mm in 
macular areas 0.19-0.26 (Table 1); maximum apertural diameter in mm in 
intermacular areas 0.14-0.16 (Table 2). 

LONGITUDINAL SECTION 

Zooecia and mesopores subprostrate for short distance, erect centrally, all 
proceed directly to surface. Zooecial walls thin; diaphragms straight, curved, 
oblique, infundibular, rarely cystoid, occur throughout zooecia, spaced one to 
one and a half tube diameters apart. Mesopores singly or in groups of two or 
three, many terminate before reaching zooecial surface; diaphragms uniformly 
spaced, commonly 19 to 30 in 1 mm. 

Remarks 

The presence or absence of acanthopores is a distinguishing feature of Mesotrypa 
species. M. discoidea Ulrich (1893: 260), M. quebecensis (Ami, 1892: 101), 

Table 2. Measurements of the taxonomic characters of Mesotrypa distincta. 

Measurements are given in millimetres. Figures in parentheses denote ranges. 

n Mean ± S.E. 

Number of zooecia in 2 mm in intermonticular area 

Number of entire mesopores in 1 mm 2 in intermonticular area 

Maximum apertural diameter of zooecia in monticules 

Maximum apertural diameter of zooecia in intermonticular area 20 



20 


8.5 ± 0.10 




(8-9) 


20 


22.5 ± 0.98 




(16-31) 


20 


0.2 ± 0.006 




(0.19-0.26) 


20 


0.2 + 0.003 




(0.14-0.18) 




B 




Fig. 2 a-b. Mesotrypa distincta Parks, lectotype, rom 1200hr. 

a. Longitudinal section, X48.6 

b. Tangential section, X48.6 



and M. rotunda Ulrich (1893: 262) from the Trenton all lack acanthopores, as 
does M. distincta from the Humber Member, Dundas Formation; these four 
species are similar when considered qualitatively, but no quantitative analysis is 
available for the Trenton taxa. Mesotrypa diver sa (Fritz, 1971) from the Humber 
Member has acanthopores; however the zoarial shape and surface configuration 
of that species are unique among species known to the writer. M. patella (Ulrich, 
1890: 458), M. orbiculoidea Cumings and Galloway (1913: 432), and M. 
pauca Utgaard and Perry (1964: 69), all of Richmond age, have acanthopores. 
Of these species, M. distincta resembles most closely M. patella except for the 
absence of acanthopores in the former. Measurements of the taxonomic charac- 
ters of M. distincta are recorded in Table 2; they may serve later in comparing 
similar taxa unknown at present to me. In view of the combination of features 
recognized in this taxon, I consider it to be a distinct species appropriately named 
Mesotrypa distincta. 

Locality 

Dundas Formation (Humber Member), Humber River, Toronto, Ontario. 

Types 

Lectotype rom 1200hr; paralectotypes rom 30726. 

Genus Peronopora Nicholson, 1881 

Description 

Description of Peronopora revised by Boardman and Utgaard (1966). 

Type Species 

Chaetetes decipiens Rominger, 1886. 

Peronopora vera Nickles, 1905 

Fig. 3a-d 

Peronopora vera Ulrich, 1888, nomen nudum 

Peronopora vera Nickles, 1905: 46 

Peronopora vera Ulrich- Parks and Dyer, 1922: 7. 

Description 

Parks and Dyer (1922) described this material as follows: 

This species is not uncommon in the quarry on the Don River and has often been 
mistaken for Heterotrypa frondosa. The figures of tangential sections show the charac- 
teristic appearance of true tangential section on the left-hand side; on the right-hand 
side the section is deeper and slightly inclined showing both zooecial tubes and meso- 
pores in inclined or longitudinal section. The vertical section, from a photomicrograph, 
is shown without retouching in Plate n, Figure 5; it is rather confused owing to the 
impossibility of cutting a section exactly parallel to the various elements. The drawing 
was made by combining the most typical parts shown by the same thin section. The 
median plane is marked by a very thin line on both sides of which appear the bases of 
the zooecial tubes and of the mesopores which seem to alternate with a considerable 
degree of regularity. The base of the zooecial tube is trapezoidal and small, that of the 
mesopore is hexagonal and larger. The mesopores are crossed by crowded diaphragms 
throughout: the zooecial tubes have diaphragms in the lower half and cystiphragms in 
the upper. 

10 




Fig. 3 a-d. Peronopora vera Nickles, plesiotype, rom 1083hr. 

a. Tangential section, X48.6 c. Longitudinal section, X48.6 

b. Longitudinal section, X48.6 d. Tangential section, X48.6 



11 



Emended Description 

Specimen, fragment of a subfrondescent, bifoliate zoarium, covers an area of 
45 by 25 mm with maximum thickness of 2 mm; a few small, rounded, irregularly 
spaced protuberances that rise above the surface, varying in size, may represent 
aborted branches. Surface with low monticules composed of zooecia larger than 
those in intermonticular areas. Acanthopores, blunt to somewhat pointed, 
protrude beyond the surface. 

TANGENTIAL SECTION 

Zooecial apertures near surface round to subangular, seven to eight in 2 mm 
(Table 3). Zooecial walls thin, 0.01 mm (or less) in deep sections, 0.02 to 0.03 mm 
at surface, and up to 0.04 mm in monticules, concentrically laminated. Mesopores 
numerous, surround zooecia (Table 3), angular to subangular, vary ng in size 
and shape, some with an areal extent close to that of certain zooecia, occasionally 
a cluster of mesopores in monticules. Acanthopores numerous, locally inflecting 
(Table 3), varying in diameter from 0.02 to 0.05 mm depending on where section 
cuts the structure, central lumen, surrounded by concentric laminae, lumen at 
times obscured by pyrite deposit. Monticules with larger zooecia than in inter- 
monticular areas. Maximum apertural diameter of zooecia in monticular areas 
in mm 0.19-0.27 (Table 3); maximum apertural diameter of zooecia in inter- 
monticular areas in mm 0.14-0.19 (Table 3). 

LONGITUDINAL SECTION 

Zooecia prostrate for short distance on either side of mesotheca, then becoming 
erect to zoarial surface, or they may be erect to the surface from the outset; 
mesotheca with median lamella. Zooecial walls thin, laminae thickening slightly 
towards surface, lam nae convex outward, steeply inclined and merging with 
diaphragms and cystiphragms, and with diaphragms in mesopores. Diaphragms 
in zooecia straight, curved, or sigmoidal, commonly in immature zone, spaced 
one-quarter to one-half tube diameters apart and followed on distal wall by 
overlapping cystiphragms, in longer zooecia from six to nine diaphragms and 
cystiphragms occur. Above the immature zone, mesopores, mostly erect to surface, 
contain closely and regularly arranged, usually straight diaphragms. Acantho- 
pores numerous, usually observed in wall, but at times seen to cross a zooecium 
obliquely, wall relatively coarsely laminate, laminae convex outward and diverg- 
ing at a low angle from central lumen, then passing into diaphragms and cysti- 
phragms. 

Remarks 

In 1888, Ulrich named Peronopora vera but he did not describe or figure it. His 
type No. 43943, with accompanying thin sections, is in the United States National 
Museum. Donald Dean has kindly loaned this material to me for comparison 
with Parks and Dyer's plesiotype. I find that the two are similar qualitatively 
and that no significant difference occurs quantitatively (Table 3). 

Locality 

Dundas Formation, Upper Ordovician, Don Valley Quarry, Toronto, Ontario. 

Type 

Plesiotype rom 1083hr. 

12 



'•d 

CO 

CO 

c 

*■> 

la 

i 

a 
a 
co 



ON 



* 

in 

co" 
cn 



On 






oo 

CO 



co 

ON 

co 
Z 



w 

CO 

+1 

d 

CO 

s 



«o co 

On On VO Q ^-s Q /— , 

O co «n © oo O On 

• • /*^» • ^ • rsi • »^ 

©^or^o£>©.©. 
oocs£20Q 

+1 l +1 JL +1 7 +1 T +| T 

r^ © _L On ^t 






8 



CO 

<N 



8 



On 



o 

CN 



<N r< i-i 



O 
fN 



O 
<N 



Di 

co 

oo 
o 

S 
o 

s 



w 

CO 

+1 

d 

co 

s 



ON 
CO 



On 



00 



+l rl +' JL + 1 3 +l O 



O I*- o ON 

, T © ^ © ^ 
-r + i 9 . i 9 



CO 

o 



o 

CN 



" Ki <-" ^ 

•OCNiOwCO'— I («s <- 1 

oo *— ' co <N * -h * 

S oo O w © w 

CN 



o 

CN 



R 



o 

(N 



o 

CN 



§ 



K 
93 
c*> 

00 

o 



2 
o 

PS 
w 

2 

» 

2 
o 
a. 

o 
s 
© 

v. 
%> 

Ah 
o rf 

d 6X) 

1 - 



1 



o s 
f*5 



-3 

H 















CO 














(U 














Jo 














H 














CO 




























3 












c« 


o 












a> 


'■«-> 














3 


ea 










3 


O 

£ 


H 

CO 










3 


Uj 










o 




cO 










E 


,3 






_g 




,d 


,d 
















■J* 

d 
o 

E 

u 


c 




E 




.22 


•S 


S 
E 




E 




o 
o 

o 
o 


'o 
S 

o 
o 




T— 1 




.d 




N 


N 


d 


G 








o 


o 








u- 




Ih 


u 


£ 


00 

U 








0) 


0) 


CN 


O 

a, 
o 

E 




o 

43 
-♦-» 




E 

CO 


£ 

CO 


d 


CO 


C 

CO 


8 


t3 


•a 




t- 


o 


u. 






CO 


CO 


CO 


CO 


CO 


CO 












t-i 


u. 


'o 


i) 


1-1 
CO 


<u 




3 


3 


cu 


u> 


H 


■<-> 


4-> 


o 
o 

N 


c 


3 
o 


c 


3 




N 

U 

Cl 






+-» 




'■m 


CO 


eO 


V-, 


«t-H 


c 


<*-. 


c 






O 


o 


o 


o 


o 


E 


E 




JO 


E 


(U 
40 


E 


3 

£ 


3 

E 


£ 


£ 


fl 


E 


C 


'k 


x 


3 


3 




3 




CO 


CO 


z 


Z 




Z 




s 


S 



13 



Prasopora Nicholson and Etheridge, 1877 

Description 

The description of Prasopora may be found in Ross (1970). 

Type Species 

Prasopora grayae Nicholson and Etheridge, 1877 

Prasopora donensis Parks and Dyer, 1922 

Fig. 4a-c 

Original Description (Parks and Dyer, 1922) 

The zoarium of this species is circular and free, probably with a concentrically wrinkled 
epitheca. The diameter ranges from 17 to 20 mm and the thickness is approximately one 
millimetre. The upper surface is gently convex and the under surface correspondingly 
concave. The celluliferous surface shows that the ordinary apertures are arranged in 
quincuncial rows springing from a number of very ill-defined centres. They are usually 
hexagonal in outline and occur to the number of four in the space of one millimetre. At 
intervals of 2.5 to 3 mm are clusters of larger cells, and at about the same interval occur 
slightly defined monticules. The clusters and the monticules are not necessarily coincident 
nor are they necessarily the centres of the quincuncial systems. 

Tangential sections show that the ordinary zooecial tubes are nearly or quite circular 
but that they become elliptical as the centres of the clusters are approached. The walls 
of the zooecial tubes are comparatively thin and independent, touching each other in 
the direction of the rows but separated in other directions by a number of large angular 
mesopores. Cystiphragms appear in nearly every tube. Acanthopores are scarcely to be 
discerned but there is some evidence of very small ones at the points of junction of 
the tubes. 

Vertical sections, where ideally cut, show about five well-developed cystiphragms and 
clearly defined diaphragms in the zooecia, the latter being confined to the lower part 
of the tube. The mesopores are crowded with diaphragms. 

This species has decidedly the surface characteristics and manner of growth of the 
genus Aspidopora and approaches very closely to Aspidopora newberri [sic] Nicholson. 
We would without hesitation, ascribe the species to Aspidopora were it not for the 
undoubted diaphragms in the zooecial tubes. 

Except for the somewhat larger size, the species closely resembles Prasopora lenticu- 
lar is Ulrich. The vertical sections are almost identical, but the tangential section of 
P. lenticularis shows a closer spacing of the zooecial tubes and a less development of 
mesopores. The arrangement of the zooecial tubes in rows is apparently a feature of 
both species. 

Emended Description 

Six very poorly preserved specimens are listed as syntypes of Prasopora donensis. 
Only two warrant redescription and become the lectotype and paralectotype. 
Three are designated Prasopora cf. donensis, and one represents the brachiopod 
Trematis millepunctata Hall. 

EXTERNAL FEATURES 

Zoarium a small, free discoidal mass adhering to matrix, larger specimen before 
sectioning, 17 mm in diameter, a little over 1 mm in height; slightly convex above 
concave below, concentrically wrinkled epitheca recognized only by impression 
on matrix of a small portion of the base; monticules almost flush with surface, 
2.5 to 3 mm apai «. measuring from centre to centre, zooecia in inter-areas quincun- 
cially arranged. 

14 













Fig. 4 a-c Prasopora donensis Parks and Dyer, lectotype, rom 1084hr. 

a. Tangential section, X24.3 

b. Tangential section, XI 2.2 

c. Longitudinal section, X24.3 



15 



TANGENTIAL SECTION 

Zooecial apertures oval to circular, commonly 8 to 9 in 2 mm (Table 4). Zooecial 
wall thin 0.01 mm (or less) in width, finely laminated, individual laminae dis- 
tinguishable only under magnifications of X250 or higher. Ordinary zooecia 
surrounded by numerous angular mesopores, mesopores in 1 mm 2 19 to 37 
(Table 4), some one-third to one-half size of a zooecium, only rarely do zooecia 
come in contact, acanthopores absent, cystiphragms in most zooecia. Monticules 
composed of zooecia larger than those in intermonticular areas and with inter- 
spersed mesopores, maximum diameter zooecial aperture in monticular areas in 
mm 0.26-0.31 (Table 4); maximum diameter zooecial aperture in intermonticular 
areas in mm 0.13-0.19 (Table 4). 

LONGITUDINAL SECTION 

Zooecia, slightly recumbent in peripheral zone, erect in central area, intersect 
zooecial surface approximately at right angles. Zooecial walls finely laminate, 
distinct under high magnification, in best preserved sections five cystiphragms on 
one side only, large at base, diminishing in size towards surface, basal cysti- 
phragms may extend half way (or even farther) across a zooecium ; straight or 
oblique diaphragms, corresponding in number to cystiphragms, extend from 
cystiphragms to opposite zooecial wall. 

Remarks 

P. donensis is significantly different from P. richmondensis sp.nov. (description 
to follow) externally in that it lacks the conspicuous nodular surface of that 
species; internally in the absence of acanthopores, the presence of more numerous 
mesopores, and smaller zooecia in the intermonticular areas. 

Closely related to P. donensis is P. lenticuJaris Ulrich (1893: 253), from the 
Black River (Decorah) of St. Paul, Minnesota. The zoarium of the latter taxon 
is parasitic, a feature which may not be significant. P. lenticularis has somewhat 
smaller zooecia and only a single mesopore between the zooecia in the inter- 
monticular areas, a sharp contrast to the numerous mesopores in the same areas 
in P. donensis. Owing to the extremely poor preservation of types some doubt 
exists as to the generic reference. 

Locality 

Dundas Formation, Don Valley Quarry, Toronto, Ontario. 

Types 

Lectotype rom 1084hr, paralectotypes rom 32317 and 32318. 



16 



3 



O 

a 
-8 



.a 

■** 
a 

9> 



1/3 



c 

I 

e 
S 

cO 



# 


* 




* 


» 


* 




* 


WJ 


* 


to 


* 


t-»* 


o 


1 © 


© 


O 


© 


1 vo 


as 


*-^ 




1-H 


m 



.5 

9 



4) 

is 
S 



•2 



W 

CO 

+1 

fi 

cO 
W 

s 



o 



e'- 
en 



"S" © ^h O CM 



O /-s o 

+iT 

00 

in ^ 

CM CM 



o S o 



CM 



00 



o 

CM 



+l 3 + 1 t +l 2 + 1 2 

^) SO Ski N O h 



00 



o 

CM 



CM 



o 

CM 



^ o lN . o 

w w 



o 

CM 



o 

cm 



a 

4> 

s 

I 



&5 



w 

CO 

+1 

c 

cO 

s 



O On 

^H O 

— : • ^ 

© ^. ^ r-« 

+' ^ +• 3 

oo 0\ 

rn W IO ^H 

oo o" 

CO 



o 

CM 



o 

CM 



8 

© 
+1 


2 


d 
+1 




oo 
cm 


CM 

© 


1-H 


1— 1 

d 


d 




d 




o 




o 

CM 





.2 



S 

o 
S 

£ 



•a 
a 
w 



S 
5 

2 
o 
a 
5 



01 

H 



s 










3 






cO 










'♦3 

C 






Ui 










o 






J2 










E 






*3 
o 

•^* 

c 
o 

E 


c 
E 




£ 
E 




.2 
'o 
o 

o 


c 

cO 

'o 
53 

o 




-♦-• 


E 








o 

N 


o 

N 




,— * 








<*N 


«*-! 




fi 


# e 








o 

Ui 


o 

Ui 




B 
E 

CM 


C/5 




o 

ex 




*-> 






O 

a, 
o 




o 




E 

2 


£ 

CO 




C 


03 


c 

03 


03 


•5 


•3 


s 




E 


u, 


o 


u 






Ui 


cc) 


03 


CO 


03 


c0 


CO 


03 


•1H 










i— 


u 




O 


0) 


U 


4) 


U 


3 


fi 


u 


CJ 


u 


03 


Ui 


03 




■»— > 


CO 


O 
O 

N 


d 

0) 


3 
O 


c 


3 


c 


u 
Cn 


3 






-*— » 




+-» 


03 


03 


■«-> 


u_ 


(4—1 


c 


<*-C 


fi 






fi 


O 


o 


o 


O 


O 


E 


E 


O 


Jrt 


Ui 


E 


u, 


E 


3 


3 


E 


£ 




In 


X) 


In 

0J 


E 


E 


u, 


E 


£ 


c 


E 


49 

c 


S 


S 


c 


3 


3 




3 




cO 


CO 




z 


2 




z 




s 


s 





17 



Prasopora richmondensis sp.nov. 
Fig. 5a-c 

Monticidipora parasitica multipora Dyer. 1925: 71. 

Description 

Dyer (1925) included the specimen rom 12169, herein described, among the 
syntypes of Monticidipora parasitica multipora. He must have based his identifica- 
tion upon the somewhat similar nodular surface of the zoarium of his variety. 
Thin sections prepared from the specimen for this revision indicate that it repre- 
sents the new species P. richmondensis. 

EXTERNAL FEATURES 

Zoarium an irregular shaped mass, part of which encrusts the brachiopod 
Hebertella or Platystrophia. Specimen 15mmX 17 mm, greatest thickness 
1.75 mm, petering to 1mm at periphery. Surface with prominent irregularly 
spaced unequal monticules, the smaller of which are conical, others larger and 
stouter, still others coalesce to form elongate elevations. 

TANGENTIAL SECTION 

Zooecia mostly circular but slightly angular near surface, commonly 8 to 9 in 
2 mm (Table 5), zooecial walls thin, concentric laminae only faintly distinguish- 
able, walls generally less than 0.01 mm thick below surface, 0.01 to 0.02 mm near 
surface. Mesopores, small and angular, rarely one-third size of zooecia, surround 
most zooecia (Table 5) and less abundant where zooecia are subangular. Acantho- 
pores moderately abundant (Table 5), 0.02 to 0.05 mm in diameter with small 
lumen surrounded by dark concentric laminae, occasionally acanthopores indent 
zooecial aperture. Monticules composed of larger zooecia than in intermonticular 
space and with interspersed mesopores. Cystiphragms occupy from one-half to 
one-third area within each zooecium. Maximum apertural diameter of zooecia 
in monticules in mm 0.26-0.31 (Table 5); maximum apertural diameter of 
zooecia in intermonticular areas 0.18-0.22 mm (Table 5). 

LONGITUDINAL SECTION 

Zooecia arise directly from the brachiopod and free basal portion and continue 
in a straight course to the surface of the zoarium. Walls uniformly thin through- 
out. Each zooecium with cystiphragms and straight diaphragms in regular 
sequence throughout their length, within space of 1.75 mm 12 cystiphragms and 
12 diaphragms occur. Acanthopores with clear central area, flanked by fine 
laminae, appear at various levels through the entire growth. 

Remarks 

P. richmondensis sp.nov. may be distinguished from P. donensis Parks and Dyer 
by the conspicuous nodular surface, by the presence of acanthopores, and by 
fewer mesopores. The taxon is similar to P. nodosa Ulrich (1882b: 245) in external 
appearance, although Ulrich did not consider the zoarium to be parasitic. 
Through the courtesy of R. S. Boardman and D. A. Dean of the United States 
National Museum, I have been privileged to examine Ulrich's syntypes of 
P. nodosa (usnm 43691) from the Trenton (Cathys Limestone), Nashville, Ten- 

18 




Fig. 5 a-c. Prasopora richmondensis sp.nov., holotype, ROM 12169. 

a. Longitudinal section, X48.6 

b. Tangential section, X48.6 

c. Tangential section, X48.6 



19 



Qi 

o 

4> 



.a 



03 

o 

c 

I 

a 
5 

03 






q 



r4 



* 
* 






.s 

a 

•a 



SO 

•1 

s 

8 
5 

S 
'C 

2 

o 

o 



2 
5 
a. 



S 

2 
o 
a 
& 

3 
u 

•«* 

e 
o 



O gg 

IS 

o g 



— 

CI 

H 



s: 

i 






2 

.5, 



2 



w 

C/5* 
+1 

C 

03 



o 






5 8-8 






w 

CO 

+1 

d 

CO 

s 



^ g-^ ^ ^ o ^ q w d 

+l 2 +l 2 +l 3 +l 2 +l j 



8 



O 



O 



M N O 



1—1 1—1 

+i 7 +i 2 

<^> Q © — 

d d 

1-H <N 



o 



o 



<N 



o 



<N 



O 



+1*? +i2 

i— i i— i *»0 — 

°i d 1 d 

o w o w 



o 



o 















03 














U 














hi 














cd 














H 














C3 




























3 














o 












C/5 














D 


'■♦-• 














d 


a 










3 


o 


<u 










O 


£ 

H 

d 


c3 










'-t-> 

d 
o 

£ 














3 






_c 




# d 


d 


•^H 














c 

o 

£ 


£ 




C4 

£ 

£ 




.2 
o 


.2 

<u 
o 


u 


£ 

1-H 




,_h 




o 


o 


a 




_c 




N 

(4-1 


N 

(4H 


e 


r g 




t/5 




o 


o 








Ui 




u 


u 


£ 


</) 




o 




s 


<u 






a 








£ 


o 
a, 
o 

(A 


C3 


o 

e 


C3 
CD 


£ 
*3 


£ 

03 

-5 




£ 


l-c 


o 


IU 






.22 


c3 


a 


C3 




03 


o 


a> 


1— 


<u 


u- 


3 


3 


<U 


M 


BQ 


Uh 


ca 


<-> 


■♦-» 


o 


•t-j 


3 


*-2 


3 


1) 




o 

N 


d 


o 

•3 


G 

1> 






ex 

03 


«*-. 


'■*-. 


C 


(4-1 


c 






o 


o 


o 


O 


o 


£ 


£ 


H 


u 


£ 
u 


Ui 


E 

t-c 


3 


3 




0) 


0) 
X> 


£ 


£ 


£ 


£ 




£ 


c 


'H 


>< 

03 


3 


3 




3 




rt 


z 


z 




z 




S 


S 



20 



nessee. The two are similar externally and in the number of zooecia in 2 mm in the 
intermonticular areas. The monticules, however, are dissimilar; in P. nodosa 
numerous tiny, angular mesopores, varying in shape and size, surround the 
zooecia or form elongate, stellate, or irregular aggregations. Ulrich states that 
"a moderate number of spiniform tubuli may be observed in tangential sections". 
I fail to distinguish these structures in his sections. It is possible he confused them 
with the solid ends of pinched-out mesopores. No acanthopores are visible in his 
longitudinal sections. 

To describe a new species on a single specimen is admittedly a weakness, nor 
have I been able to locate a comparable species from a similar stratigraphic 
horizon after a careful perusal of the pertinent literature available to me. As 
pointed out in the preceding paragraph, Prasopora nodosa Ulrich from the Middle 
Ordovician (Trenton) is the closest species with which Prasopora richmondensis 
may be compared. It is conceivable that Prasopora richmondensis is an evolution- 
ary derivative of that older taxon. 

Locality 

Meaford Formation, Streetsville, Ontario. 

Type 

Holotype rom 12169. 



21 



Acknowledgments 

Thanks are expressed to Janet Waddington, Curatorial Assistant, Department of 
Invertebrate Palaeontology, rom, for calculating the Mann-Whitney U Statistics; 
to Huibert Sabelis for the restoration of original thin sections and for the prepara- 
tion of new sections required for the research; to Joan Burke for her valued 
secretarial assistance and for typing the manuscript. 

The photographs were taken by Mr. Brian O'Donovan, Department of Geology, 
University of Toronto. 



22 



Literature Cited 

AMI, H. 

1892 Notes and descriptions of some new or hitherto unrecorded species of fossils from 
the Cambro-Silurian (Ordovician) rocks of the Province of Quebec. -Canadian 
Record of Science, 5(1): 96-103. 

ARMSTRONG, H. S. 

1945 Stigmatella in the Ordovician of the Central Ontario Basin. -Journal of Paleontology, 
19(2): 149-157. 

BOARDMAN, R. S. and J. UTGAARD 

1966 A revision of the Ordovician bryozoan genera Monticulipora, Peronopora, Hetero- 
trypa, and Dekayia. -Journal of Paleontology, 40(5): 1082-1108. 

CUMINGS, E. R. and J. J. GALLOWAY 

1913 The stratigraphy and paleontology of the Tanner's Creek section of the Cincinnati 
series of Indiana. -37th Report, Indiana Department of Geology, Natural Re- 
sources, 1912: 353-479. 

d'orbigny, a. d. 

1849 Prodrome de paleontologie stratigraphique universelle des animaux mollusques & 
rayonnes, faisant suite au cours elementaire de paleontologie et de geologie strati- 
graphiques. Vol. 1. -Paris, V. Masson. 394 pp. 

DYER, W. S. 

1925 The stratigraphy and paleontology of Toronto and vicinity. Part V. The paleontology 
of the Credit River section. -Report of the Ontario Department of Mines, 1923. 
32(7): 47-88. 

FOERSTE, A. F. 

1924 Upper Ordovician faunas of Ontario and Quebec. -Memoir of the Geological 
Survey Branch, Canada, 138: 1-255. 

FRITZ, M. A. 

1970 Redescription of type specimens of the bryozoan Hallopora from the Upper Ordo- 
vician of Toronto region, Ontario. -Proceedings of the Geological Association of 
Canada, 21: 15-23. 

1971 The trepostomatous bryozoan Stigmatella catenulata diver sa Parks and Dyer (1922), 
a synonym for Mesotrypa diversa (Parks and Dyer). -Life Science Occasional Paper, 
Royal Ontario Museum, 18: 1-6. 

1973 Redescription of type specimens of bryozoan Stigmatella from the Upper Ordovician 

of the Toronto region, Ontario. -Life Science Contribution, Royal Ontario Museum, 

87: 1-31. 
1 975 Redescription of type specimens of the bryozoan Heterotrypa from Upper Ordovician 

rocks of the Credit River valley, Ontario. Canada. -Life Science Contribution, 

Royal Ontario Museum, 101 : 1-30. 

LIBERTY, B. A. 

1969 Palaeozoic geology of the Lake Simcoe area, Ontario. -Memoir of the Geological 
Survey Branch, Canada, 355: 1-201. 

NICHOLSON, H. A. 

1874 Description of species of Chaetetes from the Lower Silurian rocks of North America. 

-Quarterly Journal of the Geological Society of London, 30(38): 499-515. 
1879 On the structure and affinities of the "tabulate corals" of the Palaeozoic period, with 

critical descriptions of illustrative species. -Edinburgh, W. Blackwood. 342 pp. 
1881 On the structure and affinities of the genus Monticulipora and its sub-genera, with 

critical descriptions of illustrative species. -Edinburgh, W. Blackwood. 240 pp. 

23 



NICHOLSON, H. A. and R. ETHERIDGE, JR. 

1877 L. Contributions to Micro-Palaeontology. -II. On Prasopora grayae, a new genus 
and species of Silurian corals. -The Annals and Magazine of Natural History, 
4th series, 20(119): 388-392. 

1878 Description of species. Monograph of Silurian fossils of the Girval district, Ayrshire, 
Scotland. Fasc. 1. -Edinburgh, W. Blackwood. 135 pp. 

NICKLES, J. M. 

1905 The Upper Ordovician rocks of Kentucky and their bryozoa. -Bulletin of the 
Geological Survey of Kentucky, 5: 1-64. 

parks, w. A. 

1924 Upper Ordovician at Toronto, Ontario. -Bulletin of the Geological Society of 
America, 35(1): 103-104 [Abstract]. 

1925 Addenda et Corrigenda (Parts I to IV). -Report of the Ontario Department of 
Mines, 1923, 32(7): 35-38. 

parks, w. a. and w. s. dyer 

1922 The stratigraphy and paleontology of Toronto and vicinity. Part II. -The Mol- 
luscoidea. -Report of the Ontario Department of Mines, 1921, 30(7): 1-59. 

rominger, c. 

1866 Observations on Chaetetes and some related genera, in regard to their systematic 
position; with an appended description of some new species. -Proceedings of the 
Academy of Natural Sciences of Philadelphia, 18: 113-123. 

ROSS, J. P. 

1970 Champlanian Ectoprata (New York State), Pt. III. -Journal of Paleontology, 
44(2): 346-382. 

siegel, s. 

1956 Nonparametric statistics for the behavioral sciences. -New York, McGraw-Hill. 
312 pp. 

ULRICH, E. O. 

1882a American Palaeozoic Bryozoa. -Journal of the Cincinnati Society of Natural History, 

5(3): 121-175. 
1882b American Palaeozoic Bryozoa. -Journal of the Cincinnati Society of Natural History, 

5(4): 232-257. 
1886 Lower Silurian Bryozoa of Minnesota with preliminary descriptions of some new 

species. Minnesota Geological and Natural History Survey, 14th Annual Report 

(III). -J. W. Cunningham & Co., State Printers, St. Paul, Minnesota: 57-103. 
1888 A correlation of the Lower Silurian horizons of Tennessee and of the Ohio and 

Mississippi Valleys with those of New York and Canada. -The American Geologist, 

2(4): 39-44. 
1890 Part II. Palaeontology of Illinois. Section VI. Palaeozoic Bryozoa. -In Worthen, 

A. H. Geological Survey of Illinois. Volume 8. Geology and Palaeontology. Edited 

by J. Lindahl, Springfield, 111. Published by authority of the Legislature of Illinois, 

pp. 285-677. 
1893 On the Lower Silurian Bryozoa of Minnesota. The Geological and Natural History 

Survey of Minnesota, 1895. -Harrison & Smith, State Printers, 3(1): 96-332. 

ulrich, e. o. and r. s. bassler 

1904 A revision of the Paleozoic Bryozoa. Part II. On the genera and species of Treposto- 
mata. -Smithsonian Miscellaneous Collections, 47: 15-55. 

UTGAARD, J. and T. G. PERRY 

1964 Trepostomatous bryozoan fauna of the upper part of the Whitewater Formation 
(Cincinnatian) of eastern Indiana and western Ohio. -Bulletin of the Indiana Depart- 
ment of Conservation, Geological Survey, 33: 1-111. 



24 



■L 



-■••'' 



£M 



- £ *-'.'~- 



'•>-*-> 

'.". ^V 



xEi 






m l 



ISBN: 0-88854-184-8