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 EntomolUJiUS 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 Razoumowsld, 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 on the subject, no vestige of 



