ORDOVICIAN TRILOBITES FROM THE TOURMAKEADY LIMESTONE 
DISCUSSION. Fortey (1979: 100) has discussed the evolutionary 
trends evident in Benthamaspis, culminating in the considerably 
effaced species B. diminutiva Hintze, 1953. A species from the 
Tourmakeady Limestone is of interest in that it is the youngest 
known member of the genus and confirms the stratigraphically 
correlated pattern of progressive effacement. The species is very 
similar to the slightly older (Zone J) B. diminutiva, from Ibex, Utah, 
but differs in the possession of narrower palpebral lobes, more well 
impressed axial furrows, and retention of a complete, if very shal- 
low, preglabellar furrow. The preglabellar furrow of B. diminutiva is 
effaced, so that the glabella grades anteriorly toward the anterior 
border furrow (Hintze 1953: pl. 13, figs 9b, 10c). In addition to 
effacement, the species are united by their nearly identical pygidia 
(compare PI. 11, fig. 23, with Hintze 1953: pl. 13, figs 11a, 11b), and 
by the laterally concave glabellar margins. Most older Ibexian 
species have the axial furrows anteriorly convergent, but there is 
some indication of the beginnings of the axially bowed form with an 
anteriorly expanding glabella in certain specimens of B. conica 
Fortey, 1979, from the Catoche Formation of western Newfound- 
land (see particularly Fortey 1979: pl. 35, fig. 7). The librigena of B. 
diminutiva is not known, but that of the Irish taxon (PI. 11, fig. 19) 
agrees well with those assigned to earlier species (Fortey 1979: pl. 
34, fig. 3; pl. 35, fig. 4). We also figure as Benthamaspis sp. two 
cranidia with distinct borders (It 25941, 25942; Pl. 1, figs 7,9) which 
are probably not conspecific with B. aff. diminutiva; a pygidium 
(It 25943; Pl. 1, fig. 8) may belong with these cranidia. 
Family TELEPHINIDAE Marek, 1952 
Subfamily TELEPHININAE Marek, 1952 
Genus OOPSITES Fortey, 1975a 
TYPE SPECIES. Telephus hibernicus Reed in Gardiner & Reynolds, 
1909, from the Tourmakeady Limestone, upper Arenig, Ireland; by 
original designation. 
DISCUSSION. Oopsites was erected (Fortey 1975a: 95) as an ex- 
plicit “morphological and stratigraphic intermediate’ between the 
genera Goniophrys Ross, 1951, and Telephina Marek, 1952. As 
such, it may well prove paraphyletic. The situation, however, would 
be better understood in light of a comprehensive phylogenetic 
review of the telephinids, a task beyond the scope of the present 
work, and the original classification is retained herein. 
Oopsites hibernicus (Reed in Gardiner & Reynolds, 1909) 
Pl. 11, figs 10-12, 15; Pl. 13, figs 1-3; Pl. 16, fig. 24 
101 
1975a Oopsites hibernicus (Reed); Fortey: 97; pl. 33, figs 9-19; pl. 
34, figs 1-7. 
Oopsites hibernicus (Reed); Morris: 156. 
MATERIAL. ‘Topotypes It. 26081—26083, 26086-26088, 26111— 
26113, 26176. 
DISCUSSION. Fortey (1975a: 97, pl. 33, fig. 8) designated and 
illustrated a lectotype from Reed’s (in Gardiner & Reynolds 1909) 
syntypes. This has been the only photographic illustration of a type 
specimen to date, although Fortey (1975a) figured well preserved 
Spitsbergen material assigned to the species. The additional Irish 
material figured herein confirms the specific identity with the 
Spitsbergen taxon beyond any doubt. The only possible difference 
between the two lots of specimens is that the palpebral furrow of the 
Spitsbergen cranidia is slightly deeper anteriorly than that of the 
Irish specimens (compare Fortey 1975a: pl. 33, fig. 12; pl. 34, fig. 6, 
with Pl. 13, fig. 1b). 
1988 
Subfamily OPIPEUTERINAE Fortey, 1974 
DISCUSSION. Opipeuteridae was originally proposed as a 
monogeneric family by Fortey (1974), who considered that this 
specialised pelagic form might be closest to remopleuridoids. 
Shergold (in Laurie & Shergold 1996) demonstrated that it is instead 
closely related to Carolinites, and hence a member of the 
Telephinidae. It is not yet clear how the Carolinites + Opipeuter 
group, whichis very likely monophyletic, relates to other telephinids. 
Dean (1971) introduced the subfamily Carrickiinae to accommodate 
Carrickia, and the relationship of this genus to Telephina and 
Goniophrys, and all of these to Carolinites and Opipeuter, is as yet 
unclear. For the time being Opipeuterinae is retained as a subfamily 
of telephinids, to include Opipeuter and Carolinites, pending the 
clarification of their relaitonships to other pelagic taxa. 
Genus OPIPEUTER Fortey, 1974 
TYPE SPECIES. Opipeuter inconnivus Fortey, 1974, from the Val- 
hallfonna Formation (Arenig) of Spitsbergen; by original designation. 
Opipeuter aff. inconnivus Fortey, 1974 
Pl. 11, figs 13, 14, 16, 20; Pl. 13, figs 4, 5 
MATERIAL. Assigned specimens It. 26087, 26088, 26108, 26109, 
26114, 26115. 
DISCUSSION. Opipeuter inconnivus was fully described by Fortey 
(1974) who included within that species a cranidium from the 
Tourmakeady Limestone. There are three species in stratigraphical 
succession through the Arenig, each with progressively narrower 
anterior glabellar tongues: O. angularis (Young, 1973), O. inconnivus, 
and Opipeuter. sp. A of Fortey (1974), the last-named also having a 
1909 Telephus hibernicus Reed in Gardiner & Reynolds: 149; pl. 
6, figs 10, 11. 
1930 Telephus hibernicus Reed; Ulrich: 17; pl. 2, figs 18, 19. 
1968 Telephina hibernica (Reed); Whittington: 56. 
PLATE 11 
Figs 1-9 Ceraurinella sp. 1, It. 26072, cranidium, dorsal view, x8. 2, It. 26073, cranidial fragment, dorsal view, x6.5. 3, It. 26074, cranidial fragment, 
dorsal view, x6.5. 4, It. 26075, right librigena, external view, x10. 5, It. 26076, pygidium, dorsal view, x8. 6, It. 26077, pygidium, dorsal view, x6.5. 7, It. 
26078, left librigena, external view, x10. 8, It. 26079, right librigena, external view, x3.5. 9, It. 26080, pygidium, dorsal view, x10. 
Figs 10-12,15 Oopsites hibernicus (Reed in Gardiner & Reynolds, 1909). 10a-b, It. 26081, cranidium, left lateral and dorsal views, x10. 11, It. 26082, 
cranidium, dorsal view, x15. 12a-b, It. 26083, cranidium, dorsal and anterior views, x10. 15a-b, It. 26086, thoracic segment, anterior and dorsal views, 
SGI: 
Figs 13, 14, 16,20 Opipeuter aff. O. inconnivus Fortey, 1974 13a-b, It 26108, cranidium, dorsal and left lateral views, x10. 14a-b, It 26109, cranidium, 
anterior view, x10. 16, It. 26087, thoracic segment, dorsal view, x15. 20, It. 26088, thoracic segment, dorsal view, x10. 
Figs 17-19, 21-23 Benthamaspis aff. B. diminutiva Hintze, 1953 17a-c, It. 26089, cranidium, dorsal, anterior, and left lateral views, x10. 18a-b, It. 
26090, cranidium, dorsal and anterior views, x10. 19, It. 26091, left librigena, external view, x10. 21, It. 26092, pygidium, dorsal view, x15. 22a-b, It. 
26093, pygidium, dorsal and ventral views, x15. 23a-b, It. 26094, pygidium, posterior and dorsal views, x15. 
