REPORT ON THE STOMATOPODA. 
51 
held in place by the flat oval chelae which are tightly clasped over it. At the opening it 
stretches out as far 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 abdominal 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 off 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. Squillci empusa stridulates 
vigorously in the same way, and its habits, which I have also had an opportunity to 
observe, are quite different from those of Lysiosquilla excavatrix. It is very active, 
sw im ming 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 fully grown larva, which is a long-spined 
Lysioerichthus, is shown in PI. XI. 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 
