ORDOVICIAN TRILOBITES FROM THE TOURMAKEADY LIMESTONE 
DISCUSSION. The morphology of Dimeropyge? ericina is very 
unusual, and in fact has no direct comparison among mature or 
nearly mature material of any other dimeropygid. It may be under- 
stood, however, by reference to the very early developmental 
morphology of Dimeropyge. It is well established that the protaspid 
protocranidium of members of this genus, as well as cranidia 
probably assignable to meraspid degree O or 1, have only two pairs 
of glabellar spines and four pairs of fixigenal tubercles (Tripp & 
Evitt 1983: pl. 31, figs 6, 7, 10, 11, 16, 17, 23, pl. 32, fig. 6; 
Chatterton 1994: figs 4.3, 4.6, 4.8, 4.22, 4.23, 5.1). These tubercles 
are in identical positions to the cranidial spines of D.? ericina. In 
addition, early (M3) meraspid transitory pygidia of Dimeropyge 
show unreleased thoracic segments with paired axial and fulcral 
spines similar in position to those seen in a thoracic segment of the 
Irish species (compare Chatterton 1994: fig. 4.4 with Pl. 16, fig. 19). 
Finally, D.? ericina has a fine, transverse row of rounded tubercles 
aligned along the rear of its anterior border (PI. 16, fig. 18) identical 
to that seen in juvenile Dimeropyge (e.g., Chatterton 1994: figs 4.9, 
5.1, 6.2). From this it may be hypothesized that D.? ericina is a 
paedomorph, derived through neoteny from an earlier dimeropygid. 
Much more information would be required, both on the morphology 
of the Tourmakeady species and on relevant contemporaneous and 
earlier diversity, to form an opinion about the close affinity of the 
species. Its lack of genal spines, for example, indicates it may not be 
derived from ingroup Dimeropyge, which as far as is known main- 
tains elongate genal spines from the earliest ontogenetic stages. For 
this reason, we have assigned it only provisionally to the genus. 
Family SCHARYIIDAE Osmolska, 1957 
Genus PROSCHARYIA Peng, 1990 
TYPE SPECIES. Proscharyia sinensis Peng, 1990, Madaoyu Forma- 
tion (Upper Tremadoc), northwest Hunan, south China; by original 
designation. 
DISCUSSION. Protarchaegonus sanduensis Zhou, 1981, from the 
lower Tremadoc Guotang Formation, Guizhou, is very similar to the 
type species and definitely belongs to Proscharyia. 
Proscharyia platylimbata sp. nov. 
Pl. 15, figs ?3, ?4; Pl. 16, figs 7-10, 12-16 
ETYMOLOGY. Greek platys, broad, and Latin limbatus, bordered. 
DIAGNOSIS. Proscharyia having eyes distant from glabella and 
preocular sutures divergent at low angle; glabella tapers forward 
gently and glabellar furrows effaced; preglabellar field compara- 
tively short (sag.); pygidial axis gently tapering. 
PLATE 14 
107 
HOLOTYPE. Cranidium, It. 26161 (Pl. 16, fig. 9); paratypes It. 
26118, 26159, 26160, 26162-26167; questionably assigned speci- 
mens It. 26142, 26143. 
DISCUSSION. Peng (1990) gave a full description of the type 
species, Proscharyia sinensis, which is very like the new species in 
most features. Only points of difference require discussion here. The 
glabella of the type species tapers more strongly forwards (the 
closest specimen 1s that figured by Peng 1990: pl. 19, fig. 8) and the 
glabellar furrows are more strongly incised. On the Irish specimens 
only the posterior glabellar furrow is visible, whereas two or three 
pairs are seen on the Chinese species; however, the latter are known 
from internal moulds, on which glabellar furrows are usually clearer. 
The palpebral lobes of the Tourmakeady species are further from the 
glabella, such that the width of the interocular cheek is well over half 
that of the adjacent glabella (tr.), while it is under half in the Chinese 
species. The divergence of the anterior branches of the facial sutures 
is concomitantly less, and on some specimens (PI. 16, fig. 8) they 
hardly diverge at all. However, on P. platylimbata the preglabellar 
field is much shorter (sag.) relative to the length of the anterior 
border. OnP. sinensis the length of the preglabellar field exceeds that 
of the border as measured along the sagittal line, whereas on P. 
platylimbata the border is the longer. Pygidia of P. platylimbata are 
very similar to those of P. sinensis and both are unusual among post- 
Cambrian trilobites in having well-defined segments which extend 
all the way to the pygidial margin. The better definition of the pleural 
and interpleural furrows on the Chinese species is probably a 
consequence of the internal mold preservation on which the species 
was based. 
Family RAYMONDINIDAE Clark, 1924 
Glaphuridae Hupé, 1953. 
DISCUSSION. As outlined by Ludvigsen and Westrop (in Ludvigsen 
et al., 1989: 61), Lochman-Balk’s (in Moore, 1959) Treatise classi- 
fication of Raymondinidae included ten Marjuman genera together 
with the late Sunwaptan Raymondina. Palmer (1962) and Rasetti 
(1965) transferred most of these taxa to Cedariidae, and Ludvigsen 
and Westrop considered the family Raymondinidae to be monotypic. 
As such, it contained only three species, known only from cranidial 
(in one case cephalic) material. Ludvigsen and Westrop’s illustra- 
tions, however, reveal essential correspondence in most cephalic 
features between Raymondina and the Ordovician Glaphurus. 
Most striking is the shared modification of the basal glabellar 
area, in which S1 is isolated from the axial furrow and aligned 
exsagittally, L1 and L2 are merged, and L2 is gently swollen. A 
second prominent similarity is the occurrence in either taxon of 
medially yolked librigenae. This was established for Glaphurus by 
Figs 1-17 Celmus michaelmus sp. nov. 1a-c, It. 12853, cranidium, dorsal, left lateral, and anterior views, x10 (figured Fortey & Owens 1975: fig. 1A). 
2a-d, It. 26120, cranidium, dorsal, ventral, left lateral, and anterior views, x10. 3, It. 26121, cranidium, dorsal view, x10. 4a-c, It. 26123, holotype, 
cranidium, dorsal, ventral, and right lateral views, x10. 5a-b, It. 26122, cranidium, dorsal and left lateral views, x10. 6a-c, It. 26124, cranidium, dorsal, 
anterior, and right lateral views, x7.5. 7a-b, It. 26125, cranidium, dorsal and right lateral views, x7.5. 8a-b, It. 26126, cranidium, left lateral and dorsal 
views, x10. 9a-b, It. 26127, cranidium, left lateral and dorsal views, x10. 10, It. 26128, right librigena, external view, x10. 11, It. 26129, left librigena, 
external view, x10. 12, It. 26130, left librigena, external view, x10. 13, It. 26131, left librigena, external view, x10. 14, It. 26132, left librigena, external 
view, x10. 15, It. 26133, left librigena, external view, x10. 16, It. 26134, left librigena, external view, x10. 17, It. 26135, right librigena, internal view, 
x10.view, x15. 
Figs 6, 7,9, 10 Phaseolops ceryx sp. nov. 6, It. 12856, cranidium, dorsal view, x15. 7a-b, It. 12857, cranidium, dorsal and left lateral views, x15. 9, It. 
26116, cranidium, dorsal view, x15; 10, It. 26117, cranidium, dorsal view, x15. 
Fig. 8 Proscharyia platylimbata sp. nov. It. 26118, pygidium, dorsal view, x15. 
Fig. 11 Glaphurus crinitus sp. nov. It. 26119, cranidium, dorsal view, x10. 
