2 ENGLAND TO RIO DE JANEIRO CHAP. I 
long and one thick, with a hollow passing quite through it ; 
on one end was a brown spot, which might be the stomach 
of the animal. Four of these, the whole number that we 
took, adhered together when taken by their sides; so that 
at first we imagined them to be one animal: but upon being 
put into a glass of water, they very soon separated, and 
swam briskly about. 
31st. Observed about the ship several of the birds called 
by the seamen Mother Carey’s Chickens, Procellaria pelagica, 
Linn., which were thought by them to be a sure presage of 
a storm, as indeed it proved. 
2nd September. The casting-net brought up two kinds of 
animals, different from any before taken. They came up in 
clusters, both sorts indifferently in each cluster, although 
there were much fewer of a horned kind than of the other: 
they seemed to be two species of one genus, but are not at 
all reducible to any hitherto described. 
3rd. We were employed all day in describing the 
animals taken yesterday: we found them to be of a new 
genus, and of the same as that taken on the 28th of August ; 
we called the genus Dagysa, from the likeness of one species 
to a gem. 
4th. Employed in fishing with the casting-net. We 
were fortunate in taking several specimens of Dagysa saccata 
adhering together, sometimes to the length of a yard or 
more, and shining in the water with very beautiful colours ; 
but another insect we took to-day was possessed of more 
beautiful colouring than anything in nature I have ever seen, 
hardly excepting gems. It is of a new genus, called Carciniwm, 
of which we took another species, having no beauty to boast 
of; but the first, which we called opalinwm, shone in the water 
with all the splendour and variety of colours that we observe 
in a real opal. It lived in a glass of salt water, in which it 
was put for examination, several hours, darting about with 
great agility, and at every motion showing an almost infinite 
variety of changeable colours. Towards the evening of this 
day a new phenomenon appeared: the sea was almost 
covered with a small species of crab (Cancer depurator, Linn.), 
