1. The term sometimes applied to the cephalon in trilobites (Trilobita).
2. The dorsal head covering of solid bone which occurs in many ostracoderms (Ostracodermi) (agnathan fish, see agnatha).
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。