门: 环节动物门
纲: 多毛纲（干群）
属：加拿大虫属
种: 多刺加拿大虫
描述:
多刺加拿大虫是一种鬃毛蠕虫，长约2至4厘米，背部稍扁平。头部发育一对柔软的、可伸缩的触须。其余身体部分由23个体节组成，每个体节发育一对双分支的疣足。疣足的两支各发育成束的刚毛，其中背刚毛（背侧）比神经刚毛（外侧）更长更宽，并且其尖端呈锯齿状。神经刚毛的远端向腹侧弯曲。刚毛不对称地覆盖生物体，最长、最宽的刚毛最靠近中线，所有刚毛都有细间隔的脊纹。鳃位于这两束刚毛之间。肠道沿着身体的长度笔直延伸，并有一个外翻的吻，约占身体宽度的三分之一。
Superphylum: Annelida
Class: Polychaeta (stem group)
Genus：Canadia Walcott, 1911
Species: Canadia spinosa Walcott, 1911
Description:
Canadia is a bristled worm around 2 to 4 cm long and slightly dorsoventrally flattened. A long pair of smooth, palps protrudes from the front of its head. The variation in shape seen among these tentacles suggests that the organism could contract and extend them. The rest of the body consists of 23 trunk segments, each bearing a pair of lateral biramous parapodia, which form two main bundles of chaetae, the notosetae (dorsal) and the neurosetae (lateral). The notochaetae are longer and broader than the neurochaetae, have serrated tips and form a near continuous dorsolateral covering. The distal portions of the neurochaetae are curved ventrally. The notosetae cover the organism asymmetrically, with the longest, widest setae closest to the midline. The lateral surface of the larger setae is serrated, and all the setae bear a finely spaced patterning of ridges. Gills are situated between these two bundles of setae. The gut is straight along its length with an eversible proboscis and occupies approximately one-third of the body width.
层位：寒武纪苗岭统乌溜阶，Eoredlichia-Wutingaspis生物带。
主要产地: 加拿大哥伦比亚省布尔吉斯页岩生物群，包括Fossil Ridge的Walcott, Raymond和Collins Quarries剖面, 以及Mount Field、Mount Stephen – Tulip Beds (S7) – 以及Stanley Glacier附近的剖面。
Period: Cambrian Miaolingian Series, Wuliuan Stage, Bathyuriscus–Elrathina Zone (ca. 505 million years ago).
Principal localities: Burgess Shale (‘Thick Stephen’ Formation), Walcott Quarry on Fossil Ridge, British Columbia, Canada.
Parry, L., Caron, J.-B., 2019. Canadia spinosa and the early evolution of the annelid nervous system. Science Advances, 5: eaax5858.