316 Luminousness of the Sea. 
ments for examination. About the centre of each tube or 
division there appeared a dent or depression, marked by a 
dark line, and in this hollow lay a small round body like an 
ovum. Nearer the extremities, also, were to be seen a num- 
ber of small round bodies, shaped like nails and pretty regu- 
larly disposed. In some, as in a, the tubes or joints seemed 
almost detached from each other, except where they were 
united by a small point. In others, as in J, they seemed to 
enter each other by a sharp point at the extremity; this dif- 
ference most probably arising from the position of the objects 
while under examination. The natural size of each joint 
appeared to be not larger than a grain of sand. ‘The other 
body (fig. 83. c) only occurred once to me, and it appeared 
also to be a fragment. It was coiled round in a circular 
manner like a snake, not forming a perfect circle, as the 
extremities, which were both open, did not meet. ‘Through 
its whole length it was separated into a great many divisions or 
short tubes, each band of division or septum being double, and 
each division containing a dark spot in its centre Tike an ovum. 
Natural size about the sixth of an inch in circumference. 
These eight species of animals all belong to the Acalepha 
of Cuvier ; ‘but there are other animals, more perfect and of a 
higher organisation, which have also been found to produce 
this luminousness in the sea. Several of these I have already 
mentioned, as two or three species of Cancer, &c.; but there 
are also a good many of the Crustacea, belonging to the order 
Entomostraca of Muller, which possess this property, a few 
of which Ihave already mentioned, as the Limulus noctilucus, 
an animal described and figured by Macartney (although, 
according to Leach, this insect is not a Limulus, but a species 
of a genus unknown), and the Lyncéus, which is described by 
Riville, and which Muller says very much resembles his L. 
brachytrus. While engaged in examining the animals I 
have just described, several species belonging to this order, 
became known to me, some of which were abundant at the 
times that the sea was most luminous, while others, again, 
occurred only occasionally. Some of these are evidently 
luminous, others did not appear so: but, as it is well known 
that these little creatures have the power of giving out or re- 
taining their luminousness at pleasure, it is not surprising that 
in many instances it escaped my notice; especially as they 
are extremely shortlived, dying very soon after being taken 
up out of the sea. The observations, too, of several naturalists 
of late, as Dr. Macculloch, go far to prove that the property of 
giving out light is in all probability possessed by all these 
little inhabitants of the deep ; and, as this faculty is evidently 
