ORDOVICIAN TRILOBITES FROM THE TOURMAKEADY LIMESTONE 
sections of facial suture with sharp anterior divergence in front of 
palpebral lobes; cranidium moderately vaulted, anterior section of 
facial suture running subparallel to rear of LO in lateral profile; 
cephalic border of continuous even width; cranidial anterior border 
longer medially than laterally due to oblique course of connective 
sutures; anterior border with considerable dorsal convexity, length 
(sag.) about two thirds LO, sculpture smooth; anterior border furrow 
short (sag., exsag.), posterior slope vertical and incised, anterior part 
with gentler slope leading onto border; preglabellar field slightly 
longer (sag.) than anterior border, with gentle dorsal convexity and 
smooth sculpture; axial furrows moderately convergent anteriorly, 
bowed out slightly around L1, running without interruption into 
anteriorly convex preglabellar furrow; axial and preglabellar furrows 
deeply incised, preglabellar furrow with very slight lengthening 
(sag.) medially; interocular fixigena reduced to narrow, smooth, 
slope from palpebral lobe to axial furrow; palpebral furrow absent; 
palpebral lobe elongate but very narrow, lacking obvious sculpture; 
posterior fixigena reduced to small, narrow triangle; glabella 
subtrapezoidal, with smooth dorsal sculpture; glabellar furrows very 
shallow but discernible; L1 with slight independent inflation; S1 
relatively elongate (exsag.) and directed posteromedially in distal 
part, bifurcate proximally, posterior branch nearly reaching SO; S2 
originating laterally opposite the anterior third of the palpebral lobe, 
much shorter than L1, directed posteromedially, not running proxi- 
mally as far as S1; S3 similar in shape to S2, originating opposite the 
anterior section of the facial suture in front of the palpebral lobe, 
anteromedially directed; SO slightly longer (sag., exsag.) than 
preglabellar furrow, deep, not as incised as axial furrows, slightly 
longer behind L1; LO elongate and shelflike, longest medially, with 
smooth dorsal sculpture; median occipital node small, protruded 
posteriorly from posterior margin; axial furrow shallowed greatly 
opposite LO; posterior border furrow relatively shallow; posterior 
border short (exsag.), dorsally convex; occipital doublure underlying 
three quarters the length of LO; fossula not obvious. 
Librigenal field with width at midlength of eye 35-40% of 
exsagittal length, sculpture smooth; eye socle not evident; eye large, 
width about 60% of exsagittal length; lateral border furrow and 
posterior border furrow of similar moderate depth; lateral border 
furrow shallowing abruptly in front of base of genal spine; lateral 
border not inflated, low dorsal convexity, with single terrace line set 
laterally and running subparallel to margin; genal spine relatively 
short and subtriangular, tapering distally to sharp tip; doublure with 
four or five linear, parallel, and evenly spaced terrace lines. 
Rostral plate small and subtriangular, librigenal terrace lines 
continuous, with slight offset across connective sutures. 
Hypostome and thorax unknown. 
Pygidium with sagittal length 62-68% of anterior width; axis 68— 
69% of sagittal length of pygidium; three axial rings present, 
becoming increasingly less well defined posteriorly; first ring fur- 
row well impressed, second very shallow; axial furrows gently 
convergent, forming broad arc posteriorly to completely define rear 
of axis; three pleural and two interpleural furrows defined, 
posteriormost almost completely effaced; furrows stop short of 
pygidial margin, but no true border developed. 
113 
DISCUSSION. Phaseolops ceryx is distinguished from P. sepositus 
in the effacement of its glabellar furrows, lack of tuberculate sculp- 
ture on preglabellar and librigenal fields, lack of eye socle, and 
possession of pygidium with a smooth versus broken margin. 
ACKNOWLEDGEMENTS Preparation of this study was funded by NERC 
grant GR3/09654. We are grateful to D. J. Siveter (University Museum, 
Oxford) for review of the manuscript. 
REFERENCES 
Adrain, J. M. & Chatterton, B. D. E. 1995. The otarionine trilobites Harpidella and 
Maurotarion, with species from northwestern Canada, the United States, and Aus- 
tralia. Journal of Paleontology, Lawrence, 69: 307-326. 
& Kloc, G. J. 1997. Lower Devonian aulacopleuroidean trilobites from Okla- 
homa. Journal of Paleontology, 71 (3). 
Ahlberg, P. 1992. Agnostid trilobites from the Lower Ordovician of southern Sweden. 
Transactions of the Royal Society of Edinburgh: Earth Sciences, 83: 539-70. 
Angelin, N. P. 1854. Palaeontologica Scandinavica. I: Crustacea formationis 
transitionis. Fascicule 2: 21-92, 41 pls. Lipsiae. 
Balashova, E. A. 1961. Some Tremadoc trilobites of the Aktyubinsk Region. Trudy 
Geologischeskii Instituta SSSR, Moscow, 18: 102-145, pls 1-4. [in Russian] 
Barrande, J. 1872. Systeme silurien du centre de la Boheme, Iére Partie; Recherches 
paléontologiques, 1, Supplément, 647 pp, pls 1-35. Prague & Paris. 
Barton, D. C. 1916. A revision of the Cheirurinae, with notes on their evolution. 
Washington University Studies, Scientific Series, St. Louis, 3: 101-152. 
Billings, E. 1865. Palaeozoic fossils. Vol. 1 (4): 169-344. Geological Survey of Canada, 
Montreal. 
Bradley, J. H. 1925. Trilobites of the Beekmantown in the Phillipsburg region of 
Quebec. Canadian Field Naturalist, Ottawa, 39: 5—9. 
Brathwaite, L. F. 1976. Graptolites from the Lower Ordovician Pogonip of western 
Utah. Geological Society of America Special Papers, New York, 166: 1-106, pls 1— 
ANI. 
Bridge, J. 1931. Geology of the Eminence and Cardareva quadrangles. Missouri 
Bureau of Geology and Mines, St. Louis, 2nd Series, 24: 1-228. 
Bruton, D. L. 1983. The morphology of Celmus (Trilobita) and its classification. 
Special Papers in Palaeontology, London, 30: 213-219. 
Burmeister, H. 1843. Die Organisation der Trilobiten. Georg Reimer, Berlin, 147 p. 
Chatterton, B. D. E. 1994. Ordovician proetide trilobite Dimeropyge, with a new 
species from northwestern Canada. Journal of Paleontology, Lawrence, 68: 541— 
556. 
— & Ludvigsen, R. 1976. Silicified Middle Ordovician trilobites from the South 
Nahanni River area, District of Mackenzie, Canada. Palaeontographica, Abteilung 
A, Stuttgart, 154: 1-106. 
Clark, T. H. 1924. The paleontology of the Beekmantown Series at Lévis, Quebec. 
Bulletins of American Paleontology, Ithaca, 10: 1-134, pls 1-9. 
Cocks L. R. M. & Fortey, R. A. 1990. Biogeography of Ordovician and Silurian 
faunas. In, Scotese, C.R. and McKerrow, W.S. (eds), Palaeozoic palaeogeography 
and biogeography. Memoir of the Geological Society of London, 12: 97-104. 
Cooper, B. N. 1953. Trilobites from the Lower Champlainian formations of the 
Appalachian Valley. Geological Society of America Memoir, Baltimore, 55: 1-69, pls 
1-19. 
Cooper, R. A. & Fortey, R. A. 1982. The Ordovician graptolites of Spitsbergen. 
Bulletin of the British Museum (Natural History), London, Geology, 36: 157-302. 
& Lindholm, K. 1991. A precise worldwide correlation of early Ordovician 
graptolite sequences. Geological Magazine, Cambridge, 127: 497-525. 
Dalman, J. W. 1827. Om Palaeaderna eller de sa kallade Trilobiterna. Kungliga 
Svenska Vetenskapsacademiens Handlingar, Stockholm, 1826: 113-152, 226-294, 
pls 1-6. 
Dean, W. T. 1971. The trilobites of the Chair of Kildare Limestone (Upper Ordovician) 
of eastern Ireland. Part 1. Palaeontographical Society Monograph, London, 531: 1— 
60. 
PLATE 17 
Figs 1-17 Glaphurus crinitus sp. nov. 1a-e, It. 26177, holotype, cephalon, dorsal, oblique, anterior, right lateral, and ventral views, x10. 2a-d, It. 26178, 
cranidium, dorsal, ventral, anterior, and right lateral views, x15. 3a-b, It. 26179, cranidium, dorsal and left lateral views, x15. 4, It. 26180, cranidium, 
dorsal view, x15. 5, It. 26181, cranidium, dorsal view, x10. 6, It. 26182, cranidium, dorsal view, x10. 7a-b, It. 26183, cranidium, dorsal and anterior 
views, x15. 8, It. 26184, cranidium, dorsal view, x15. 9, It. 12855, cranidium, dorsal view, x15 (figured Fortey & Owens 1975: fig. 1C). 10, It. 26185, 
cranidium, dorsal view, x15. 11a-c, It. 26186, left librigena, external, internal, and ventrolateral views, x15. 12, It. 26187, left librigena, external view, 
x15. 13, It. 26189, cranidial fragment and left librigena, external view, x10. 14, It. 26190, right librigena, external view, x10. 15a-b, It. 26188, right 
librigena, external and ventrolateral views, x15. 16, It. 26191, thoracic segment, dorsal view, x10. 17, It. 26192, left librigena, external view, x10. 
