Abstract

The gill skeleton of the enteropneust Saccoglossus mereschkowskii consists of a series of tridents. The central prong of each trident bifurcates in its ventral end. The most anterior gill skeletal element has a simple horseshoe shape. Homologues of the elements of the enteropneust gill apparatus were found in the structure of the gill apparatus of Cephalochordata. The organization of the gill skeleton of Enteropneusta and Cephalochordata can be derived from the metameric horseshoe-shaped elements. The similarity of the structure of the gill skeleton of Enteropneusta and Cephalochordata contradicts a common “upside-down theory” of the origin of Chordata.

中文翻译：

---

橡子蠕虫（Enteropneusta）的ill骨骨架与文昌鱼（Cephalochordata）的ill骨骨架相似吗？

摘要

肠球菌Saccoglossus mereschkowskii的ill骨架由一系列三叉戟组成。每个三叉戟的中央叉在其腹侧端分叉。最前g的骨骼元素具有简单的马蹄形形状。在头足目the装置的结构中发现了肠ne装置的元素的同源物。Enteropneusta和头足类动物的ill骨架的组织可以源自异型马蹄形元素。肠小肠and和头足类data的骨架结构的相似性与Chordata起源的常见“颠倒理论”相矛盾。