REPORT ON THE STOMATOPODA. 61 



held in place by the flat oval chelae which are tightly clasped over it. At the opening it 

 stretches out as for as it can reach without leaving the burrow, and dropping the armful 

 of sand it smooths it down until it is level with the surrounding surface. This process is 

 then repeated until the burrow reaches a great depth, for I have dug for three or four 

 feet without reaching the end, and all the specimens which I kept in confinement 

 burrowed to the bottom of the aquarium. 



When the burrow is finished the animal spends most of its time near the top, and as 

 the semicircular exopodites of the al)dominal appendages complete the outline formed by 

 the convex dorsal surface, it completely fills the circular tube, into which the constantly 

 vibrating scoop-like abdominal appendages carry a continuous current of water, which 

 escapes through the loose sand. 



The whole organisation of the species, — the convex body, the semicircular swimmerets, 

 the small closely approximated eyes, and the broad flat claws, — adapt it for its mode of 

 life, and it is doubtful whether any other species is more completely subterranean in its 

 habits. Although it is very common at Beaufort, I have captured only one specimen 

 while swimming, and it very rarely ventures more than a few inches from the burrow. 



Its movements when seizing its prey are so rapid that the eye can scarcely follow 

 them, and the attempt to cut ofi" its retreat with a trowel usually results in cutting the 

 animal in two, although this is the only method of capturing them which I have found 

 at all successful. 



This species, when kept in confinement, makes a faint stridulating noise by rubbing 

 the uropod against the lower surface of the telson. Squilla empusa stridulates 

 vigorously in the same way, and its habits, which I have also had an opportunity to 

 observe, are quite difi'erent from those of Lysiosquilla excavatrix. It is very active, 

 swimming swiftly through the water, and pursuing its prey to a great distance from its 

 burrow, so that it is frequently captured in the water by the trawl or sein. It inhabits 

 muddy rather than sandy bottoms, and its burrow is a shallow U-shaped tube, open at 

 both ends, and excavated entirely by the action of the current of water which is set up 

 by the abdominal appendages. . 



Ontogeny. — Lysiosquilla excavatrix is one of the few Stomatopods which have been 

 traced through their metamorphoses, and the fuUy grown larva, which is a long-spined 

 Lysioerichthus, is shown in PI. XL figs. 1-3. 



I shall show in the section on Stomatopod larvae that it probably hatches as an 

 Erichthoidina, with five pairs of biramous thoracic appendages ; the sixth, seventh, and 

 eighth thoracic somites distinct but without appendages, and the telson joined to the last 

 thoracic somite with no intervening abdominal region. In the youngest Erichthus stage, 

 however, there is a long segmented abdomen with four pairs of fully developed append- 

 ages, and the thoracic somites from the third to the eighth have no appendages, while 

 those of the first and second thoracic somites have their adult form. The lateral edges of 



