Abstract
The Silurian trilobites described below are referred to 16 genera of which 1 is new (Nonix); 21 species-level taxa are recognized of which 4 are new species (Kosovopeltis allaarti, Proetus s.l. simus, Contracheirurus errator and Nonix sauroter), 3 are previously-described species and 14 are left in open nomenclature. The biostratigraphic and palaeogeographic links implied by the trilobites are discussed after each taxon, but the fauna as a whole is similar to Wenlock faunas from Arctic Canada.
Highlights
The Silurian trilobites described below are referred to 16 genera of which 1 is new (Nonix); 21 species-level taxa are recognized of which 4 are new species (Kosol'ope/tis al!aarti, Proetus s.l. simus, Contracheirurus errator and Nonix sauroter), 3 are previously-described species and 14 are left in open nomenclature
The unique specimen described by Snajdr (1960, p. 78, pI. 36, fig. 7) as Kosovopeltis tchernychevae nov. sp. from an unknown horizon on the River Vagran, Urals, U.S.S.R. is exceedingly similar to K. allaarti
I consider that the combination of this rare character and the presence of a median spine warrant the recognition of a new genus, even though the cephalon which I have associated with the pygidium on the grounds of similarity of sculpture is hardly distinguishable from Dicranopeltis
Summary
A small hypostorne has a sculpture of small pits, and lacks the coarse tuberculation seen in all the other ceratargine elements in the fauna. North-east of Korsgaard Bjerg, central Nyeboe Land (unit 4A) At this locality, Opoa adamsi Northern slopes of Kayser Bjerg, south-east Hall Land (unit 7) Good cranidia of Sphaerexochus occur, together with poor specimens of Encrinurus. Amongst the characters shared by these forms are the extreme effacement of cephalic and pygidial furrows and on most specimens like those to hand, it is not possibie to make out the positions of cranidial muscle scars In this group of forms, large collections will be required to allow the erection of species, and for this reason I have chosen not to formally name this materiaI. South-west of Korsgaard Bjerg, south-west Nyeboe Land (unit 12A) A very well-preserved pugidium (with five articulated thoracic segments) was collected here which is compared to Ligiscus arcanus Lane & Owens, 1982 The age indicated by this, and by a fragmentary cranidium of Chiozoon is late Llandovery or early Wenlock
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