In this order there are generally from six to eight pairs of legs, and the branchiae, when present, are not enclosed in a cavity beneath the thorax, but are either suspended beneath the abdomen, or, more rarely, are attached to the thoracic legs. The shell, also, is thin, and often membranous. From all the preceding orders the Stomapoda are, of course, distinguished by the possession of pedunculate eyes. The development of the Stomapoda would appear to be by means of "Zoeae." All the Stomapoda are marine, with the single exception of the Mysis relicta of the great lakes of Sweden and North America; and the Locust Shrimp (Squilla mantis) may be taken as a good example of the order. In this Crustacean (fig. 156) the carapace is small, and does not cover the posterior half of the thorax. The eyes and antennae are attached to a somite which is not soldered to the cephalothorax. Several of the anterior appendages are developed into powerfully prehensile and hooked feet. The branchiae are attached to the first five pairs of abdominal feet. The three posterior thoracic and the abdominal appendages are in the form of "swimmerets," and the tail is expanded into a powerful fin. Besides the Locust Shrimps, the order includes the Glass Shrimps (Erichthys) and their allies, and the Opossum Shrimps (My sis).