176 THE ZOOLOGIST. 
We now come to the most interesting point in the structure 
of this or perhaps any other Crustacean. The last segment of 
the abdomen, not counting the tail segment, is armed on either side 
with two spines of a curved, triangular form, which are articulated 
into the lower part of the side of the segment, but deflected from it 
at such an angle as to allow them to overlap and rest on the two 
movable flanges of the tail. It is known that this animal 
possesses the power of producing sound in the form of a sharp 
click, and, although I have never had the good fortune to observe 
it in a living state, I am convinced that this sound is no 
doubt produced by bringing the tail plates sharply over these 
spines. In fact, I produced a sound, similar to what I imagine to 
be the correct one, by ‘‘ clicking ” a pin over the spines of my dead 
specimens. Mr. Sinel, of Jersey, informs me that he had these 
specimens alive for some time in a glass jar of sea-water, and 
was astonished at the loudness of the sound produced, even 
in some depth of water. He tells me it was as loud as that pro- 
duced by striking the palm of the left hand with three fingers of 
the right hand, and so sharp that it seemed as though the glass of 
the jar were flying in cracks, as glass does on sudden changes of 
temperature. It would be very interesting to know the advan- 
tages derived from this sound-producing power by the animal 
itself, whether it be in some way a sexual guide, or whether it 
acts as a terror to its enemies, or a means of giving notice of 
approaching danger. Any observations on these points from 
those fortunate enough to obtain living specimens would be of 
great value. 
The colour of my specimens is a bright sealing-wax red, 
shaded off to a delicate rose tint on the thorax; the large claws 
are shaded with purple, and the legs and tail plates are pale 
salmon-colour. 
Mr. Sinel informs me that the bright red is the living colour, 
but that the female is inclined to a browner hue; he noticed, 
however, that when in a glassjar, and undisturbed, the colours 
generally assumed a transparent brownish tint, but immediately 
became scarlet again when the animals were alarmed or irritated. 
Alpheus ruber is with spawn in February, and Mr. Sinel has 
just succeeded (March) in hatching out the zoe. 
(To be continued.) 
