A third specimen of the Silurian sea scorpion Eysyslopterus patteni from the Silurian of Saaremaa/Estonia is briefly described and figured. It mainly comprises a well-preserved carapace and an associated metastoma. The latter was hitherto unknown in this genus. The metastoma of the genus Eysyslopterus is vase-shaped and shows great similarity to that of Parahughmilleria spp., further supporting its attribution to the family Adelophthalmidae.

Paraconularia planicostata (Dawson, 1868) is one of two species in this genus (Sinclair, 1940) of conulariid cnidarian currently known from Mississippian strata in the Maritimes Basin in Atlantic Canada (Babcock and Feldmann, 1986). A salient characteristic of the species is the presence of a low and narrow internal carina at or near the longitudinal midline of each of the four faces of the gently tapered periderm (Van Iten et al., 2020). Paraconularia planicostata occurs in marine carbonates in the Upper Mississippian lower Windsor and lower Codroy groups in Nova Scotia and western Newfoundland, respectively (e.g., Bell, 1929; Stacy, 1953; Dix and James, 1988; Boehner et al., 1989; Boehner and Prime, 1993; Lavoie and Sami, 1998; Jutras et al., 2006; Ryan and Giles, 2017; Van Iten et al., 2020). The species is exceptionally abundant, with richly fossiliferous biohermal limestones containing up to approximately 20 specimens per 1000 cm(3) of host rock (Van Iten, unpublished observations)-a volumetric density matched by few other conulariid-bearing rock units.

The Upper Silurian Bertie Formation (Group ofD.W. Fisher, 1960; Ciurca, 1973) of New York State and Ontario, Canada, is world renowned for its spectacular eurypterids. One of these, Eurypterus remipes Dekay, 1825, holds the distinction of being the first eurypterid in the world to be described. This species is also the state fossil of New York, as signed into law by Mario Cuomo on 27 June 1984. Another species, the second one in the world to be described, Euryptenls /acustris Harlan, 1834, has been figured on a postage stamp of Canada (as Eurypterus remipes).

Abstract:  Exceptionally abundant specimens of Conularia aff. desiderata Hall occur in multiple marine obrution deposits, in a single sixth‐order parasequence composed of argillaceous and silty very fine sandstone, in the Otsego Member of the Mount Marion Formation (Middle Devonian, Givetian) in eastern New York State, USA. Associated fossils consist mostly of rhynchonelliform brachiopods but also include bivalve molluscs, orthoconic nautiloids, linguliform brachiopods and gastropods. Many of the brachiopods, bivalve molluscs and conulariids have been buried in situ. Conulariids buried in situ are oriented with their aperture facing obliquely upward and with their long axis inclined at up to 87 degree to bedding. Most specimens are solitary, but some occur in V‐like pairs or in radial clusters consisting of three specimens, with the component specimens being about equally long or (less frequently) substantially different in length. The compacted apical end of Conularia buried in situ generally rests upon argillaceous sandstone. With one possible exception, none of the examined specimens terminates in a schott (apical wall), and internal schotts appear to be absent. The apical ends of specimens in V‐like pairs and radial clusters show no direct evidence of interconnection of their periderms. The apical, middle or apertural region of some inclined specimens abuts or is in close lateral proximity to a recumbent conulariid or to one or more spiriferid brachiopods, some of which have been buried in their original life orientation. The azimuthal bearings of Conularia and nautiloid long axes and the directions in which conulariids open are nonrandom, with conulariids being preferentially aligned between 350 and 50 degree and with their apertural end facing north‐east, and nautiloids being preferentially aligned between 30 and 70 degree. Otsego Member Conularia were erect or semi‐erect, epifaunal or partially infaunal animals, the apical end of which rested upon very fine bottom sediment. The origin of V‐like pairs and radial clusters remains enigmatic, but it is probable that production of schotts was not a regular feature of this animal’s life history. Finally, conulariids and associated fauna were occasionally smothered by distal storm deposits, under the influence of relatively weak bottom currents.

Abstract Although sometimes treated as synonyms, Eurypterus remipes (Fiddlers Green Formation) and Eurypterus lacustris (Williamsville Formation) have usually been considered separate species. Conclusions have often been based on statistical methods used to examine sets of carapace measurements. Here, morphological evidence of the cuticular sculpture of the telson margin and the prominent embayment on the lateral carapace margin supports their status as separate species. These differences are consistent throughout ontogeny and between sexual dimorphs. In the interest of establishing taxonomic stability and of providing standards for comparison of morphology, neotypes have been selected for both E. remipes and E. lacustris. Two new morphological characters from the type A genital appendage and the operculum support a close relationship between E. remipes and E. lacustris. New and earlier evidence suggest that the population representing E. remipes developed into the slightly younger E. lacustris population through the process of heterochrony, and that they represent chronospecies rather than evolutionary species.

ABSTRACT The record of Ordovician Eurypterida from New York State, USA, is shown to be largely false. Twenty-nine species in 17 genera are here recognised as pseudofossils, reducing by more than 75% the total number of named Ordovician eurypterid taxa. Consequently, 10 families now have their first occurrence either later in the Ordovician or in the Early Silurian. The implications for eurypterid palaeoecology, diversity and evolution are not as straightforward as would be expected from such a drastic taxonomic revision. All Ordovician eurypterids are now known to occur in shallow-water, near-shore shales or fine-grained carbonates. Diversity measures indicate that the end-Ordovician extinction event appears to have had less effect on eurypterids than previously known, and their turnover is level in the Ordovician.