I have before described animals of this class with blue spots.

I think that a good mode of classifying these animals would be from their form of arrangement when united.
July 17.

South latitude 19 degrees 47 minutes; west longitude 3 degrees 5 minutes 30 seconds.
Found a small animal (Cymothoa) like a wood-louse, similar to the one we caught on the 15th of this month and to another taken on the 21st of November 1837.

It had seven legs on each side, besides the five which when taken out of the water it folded over its abdomen; the colour the same as before described.
Length 0.52 inch.
Width over broadest part 0.2 inch.
Length of antennae 0.2 inch.
Illustration 4, exactly the size of life, gives a good idea of it.

It lived out of the water for two or three hours and did not die until put into spirits; it ran about on the table as well as it swam in the water, so that it was evidently amphibious.