这个词是什么意思？
A subphylum of chordates intermediate between the invertebrates and the true vertebrates. It includes the LANCELETS. Its members are characterized by a NOTOCHORD which extends into the adult stage head.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D064174 · MeSH 2026。
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