Petals 5, differing slightly in size, imbricate, sometimes unguiculate, free, keel without apical appendages.

花瓣5，在尺寸方面不同稍，覆瓦状，有时具爪，离生，没有顶端附属物脊。

A jawlike appendage of an arthropod.

包括在物一族；小蜂科之蜂。

In hemicephalous larvae, the head and its appendages are reduced and partially retracted into the thorax.

半头型无足幼虫头部部分退化，后端缩入胸部，如双翅目大蚊及一些寄生性膜翅目幼虫。

The thorax and pleon bear a number of lateral appendages, including the gills, and the tail ends with a telson.

另一个古老特征是甲壳亚门物分叉足，这样足在化石中三叶虫就已经有了。