280 A HISTORY OF RECENT CRUSTACEA 



near its base. The ocular and antennal segments are 

 more or less movable, and not covered by the carapace. 

 The two pairs of maxillae are rather simply constructed. 

 The first of the two series of legs are closely applied to the 

 mouth, and from this circumstance the sub-order has re- 

 ceived its appellation of ' mouth-footed.' According to Pro- 

 fessor W. K. Brooks, in his Report on the Challenger Stoma- 

 topoda, there are about sixty species known of adults, and 

 an equal or greater number of larvee, from the tropical, 

 sub-tropical, and temperate waters of the Atlantic, Pacific, 

 and Indian Oceans. Some of the species range over the 

 whole of this area, while others are known from only 

 a single restricted locality, almost a fourth of the species 

 having been described from single specimens. They are 

 usually found in very shallow water, only one or two 

 species being reported from depths like a hundred and 

 twenty fathoms. ' The wide distribution of many of the 

 species is undoubtedly due to the great length of their larval 

 life, during which they swim at the surface, and are swept 

 to great distances by the oceanic currents.' On the other 

 hand, the adults are extremely active in their movements 

 and retiring in their habits, most of them being burrowing 

 animals, from which it results that they may long remain 

 undiscovered even in localities where they are abundant. 

 Some, like Squilla empusa, which hunt far from their 

 burrows, are often caught in nets and trawls, but ' others, 

 such as Lysiosquilla excavatrix, are the Myrmeleons of the 

 ocean, lying in wait for their prey, covered with sand, with 

 only the tips of their eyes exposed, at the mouths of their 

 very deep burrows, to the bottoms of which they dart at the 

 least alarm.' At a station where they were extremely 

 numerous, Professor Brooks could scarcely capture one, till 

 he devised the insidious plan of holding bait in one hand 

 and a trowel in the other at the mouth of the burrow, and 

 even so with his best speed the trowel often cut in two the 

 retreating quarry. 



