Asymmetron Directory References Discover 6 Animals We Ate Into Extinction 7 of History's Most Notorious Serial Killers 7 Drugs that Changed the World What Is the Emoluments Clause? Poker Hands Ranked Timeline of the 2000s 9 of the World’s Deadliest Snakes Contents Ask the Chatbot a Question Asymmetron invertebrate genus Ask the Chatbot a Question Also known as: Epigonichthyes Learn about this topic in these articles:classification In amphioxus…Amphioxus) and Epigonichthyes (also called Asymmetron)—with about two dozen species. The chordate features—the notochord (or stiffening rod), gill slits, and dorsal nerve cord—appear in the larvae and persist into adulthood.Read More Britannica ChatbotChatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.