378 
CLASS CRUSTACEA. 
1 — 9. to MM. Victor Audouin and Milne Edwards ; it is half 
a line in length, and near three in breadth, comprehending 
the thoracic extensions. It is of a rose-colour, softer on the 
oviferous sacs, with the expansions yellowish. It adheres 
closely to the gills of the lobster, and sinks deeply between 
the filaments of these organs. The species is not numerous, 
and merely to be found on some individuals. All the nicothoes 
observed by these two naturalists were provided with ovaries. 
It is probable that these Crustacea can swim before they fix 
themselves, and that their thoracic lobes have acquired their 
ordinary development; this development, as in the case of 
the Ixodes, may be the product of the superabundance of the 
nutritive juices. 
Of the Trilobites. 
In the neighbourhood of the limuli, and of the other entomos- 
traca, provided with a great number of feet, are ranged ac- 
cording to the opinion of one of my compeers of the Royal 
Academy of Sciences, M. Alexander Brogniart, and of divers 
other naturalists, those singular fossil animals, confounded at 
first under the general denomination of Entomolithiis para- 
doxus, designated at present under that of trilobites, and of 
which he has given an excellent monograph, enriched with very 
fine lithographic figures. M. Eudes Longchamps, professor at 
the university of Caen, M. le Comte de Razoumowski, M. Dal- 
man, and some other men of science, have since published 
some new observations on those fossils. We must, on the 
hypothesis in question, admit as a positive, or at least, a very 
probable fact, the existence of locomotive organs, though, 
notwithstanding all researches oil the subject, no vestige of 
