PLATE 2 
J.M. ADRAIN AND R.A. FORTEY 
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Figs 1-6,8 Protostygina coronula sp. nov. 1a-b, It. 25952, holotype, cranidium, dorsal and anterior views, x15. 2, It. 25953, pygidium, dorsal view, x15. 
3, It. 25954, cranidium, dorsal view, x15. 4, It. 25955, pygidium, dorsal view, x15. 5, It. 25956, pygidium, dorsal view, x15. 6, It. 25957, pygidium, 
dorsal view, x15. 8, It. 25958, cranidium, dorsal view, x15. 
Figs 7,10-12 /llaenus weaveri Reed in Gardiner & Reynolds, 1909 7, SM A10387, lectotype, pygidium, dorsal view, x3.5. 10a-b, SM A10316, 
paralectotype, cranidium and right librigena, dorsal and right lateral views, x5. 11, It. 25959, pygidium, dorsal view, x5. 12, It. 25960, hypostome, 
ventral view, x10. 
Fig.9 Geragnostus clusus Whittington, 1963, It. 25961, cephalic shield, dorsal view, x15. 
Sobova Formation, Upper Arenig, Turkey), although that specimen 
may well prove to be congeneric. Protostygina adumbrata Lisogor, 
1995, is known from a single fragmentary cranidium. The species, 
from the Llanvirn of Kazakhstan, is certainly congeneric with P. 
coronula, but detailed comparison will require more complete mate- 
rial. 
Family ODONTOPLEURIDAE Burmeister, 1843 
Subfamily SELENOPELTINAE Hawle & Corda, 1847 
Genus CERATOCEPHALINA Whittington, 1956 
TYPE SPECIES. Ceratocephala (Ceratocephalina) tridens 
Whittington, 1956, Edinburg Formation, lower Mohawkian, Vir- 
ginia; by original designation. 
Ceratocephalina ramskoeldi sp. nov. 
Pl. 3, figs 9, 12; Pl. 4, figs 9, 12-15 
ETyMoLocy. After Lars Ramskold, University of Uppsala. 
DIAGNOSIS. Cephalon with dense sculpture of fine tubercles; pri- 
mary ontogenetic tubercles subdued and difficult to discern in | 
holaspides; median occipital spine short; anterior border very short | 
(sag; exsag.); slender genal spine continued on to librigenal field as 
interior border; border spines not distinct; epiborder furrow broad; | 
epiborder spines small; pygidium with two marginal border spines | 
and medial triangular projection. 
HOLOTYPE. Cranidium, It. 25987 (Pl. 4, fig. 9); paratypes It. || 
25972, 25973, 25988-25990. 
DISCUSSION. The morphology and relationships of this species 
have been commented upon by Ramsk6ld (1991: 163), although 
material has not previously been illustrated. The taxon ranks among 
the oldest odontopleurids for which relatively good morphological 
information is available (see Ramskold 1991 for a review of Arenig 
species). It appears to display a mixture of features of two 
