Cyclocystoids are a poorly known, rare, extinct class of bi-facially flattened, disc shaped echinoderms, ranging from the Middle Ordovician to the Early Carboniferous. Articulated cyclocystoids are relatively common in the Ordovician but are rarer in younger strata. Here we describe Perforocycloides nathaliae new genus and species, from the early Silurian of Anticosti Island, Québec, Canada, the first articulated cyclocystoid from the Silurian of North America. This taxon is distinguished from other cyclocystoids by the number of variably sized marginal ossicles, the lack of interseptal plates, and the novelty of pores located in the distal part of the sutures between adjacent marginals on the dorsal surface. These dorsal intermarginal sutural pores led to canals which penetrated the contiguous area of the lateral surface of the marginals and emerged on the ventral surface between the cupules of adjacent marginals. These dorsal intermarginal sutural pores/canals appear to be unique to Perforocycloides and whilst their function is speculative, they provided some form of communication between the dorsal disc and the distal side of the ventral marginals/cupules. Perforocycloides most closely resembles the Ordovician–Silurian genus Zygocycloides, suggesting that this genus may have diversified more widely during the Silurian than previously reported. A review of global Silurian cyclocystoid distribution suggests taxa were geographically confined and that greatest diversity appears to have been located within Baltica. However, it also demonstrates our current limited knowledge. No specimens have been recorded from Gondwana (e.g. Africa, Australia, South America), Siberia, and North and South China, nor are any specimens known confidently anywhere from Přidolí strata.

中文翻译：

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Perforocycloides nathalieae的新属和种，来自加拿大魁北克安蒂科斯蒂岛的一种不寻常的志留系类环孢类（Echinodermata）

类脂囊囊囊肿是一类鲜为人知，罕见的绝种双面扁平盘状棘皮动物，范围从中奥陶纪到石炭纪早期。在奥陶纪，铰接的类环孢囊相对较常见，但在较年轻的地层中则较为罕见。在这里，我们描述了萘酚萘新属和新物种，来自加拿大魁北克安蒂科斯蒂岛的志留纪早期，是北美志留纪的第一个关节状环状囊藻。该分类单元与其他环类囊藻的区别在于边缘小骨的大小各不相同，隔中板的缺失以及位于背侧相邻边缘之间的缝线远端的孔的新颖性。这些背侧缝缝孔导致运河穿透边缘的外侧表面的连续区域并出现在相邻边缘的穹ule之间的腹面。这些背侧缝缝孔/管似乎是穿孔环的独特之处尽管它们的功能具有推测性，但它们在背盘和腹侧边缘/杯的远端之间提供了某种形式的连通。Perforocycloides最类似于Ordovician-Silurian属Zygocycloides，表明在志留纪期间，该属的多样性可能比以前报道的更为广泛。对全球志留纪类环孢菌分布的回顾表明，分类单元在地理上受到限制，最大的多样性似乎位于波罗的海。但是，这也证明了我们目前的知识有限。没有从冈瓦纳（例如非洲，澳大利亚，南美），西伯利亚以及华北和华南地区记录任何标本，也没有在Přidolí地层中可靠地知道任何标本。