424 Progress of Nattiral History, 



soft and glutinous that the least pressure will crush them. 

 When divided, they continue to advance in the direction pur- 

 sued by the primitive mass. In some it has been impossible 

 to discover any nerves, or orifices ; in others, there is one 

 opening. The alimentary cavity is like a bag, from which 

 issue numerous branching ramifications. M. Dugez thinks he 

 has discovered something like a system of circulation. Some 

 of them are oviparous, and others are reproductive, like Po- 

 lypi, From this it would seem that M. Cuvier's suspicions of 

 their near approach to the Fasciolae are confirmed. 



M. de Blainville has published and presented two works to 

 the Academy, partly extracted from his contributions to the 

 Dictionnaire des Sciences, The first is a monograph on jf/iru- 

 dinaceae, in which he considers their anatomy, their natural 

 history, and their uses. He divides them into twelve genera 

 or sections. 



M.. Moquin Taudon has also published a monograph on the 

 same family, but he only divides them into eight genera. 



The second work of M. de Blainville is on worms, part of 

 which is printed under the title of Manuel (T Helminthologie, 

 but it is impossible to enter into the details of this voluminous 

 subject. 



M. de Blainville is employed with M. Vieillot in editing the 

 French Fauna, which will contain the history and figure of all 

 the animals existing in France. Twenty numbers in Svohave 

 already appeared, with coloured plates. 



MM. Audouin and Milne Edwards, who have combined 

 their efforts for the progress of comparative anatomy, have 

 turned their attention to Crustacea. Their memoir contains 

 a description of the breathing organs of this class, with their 

 mechanism ; but these gentlemen do not confirm the opinion 

 started a little while back, that Crustacea have, besides their 

 branchiae, an organ more or less analogous to the lungs of 

 those classes which breathe the open air. MM. Audouin 

 and Edwards, in the hope of facilitating their researches, es- 

 tablished themselves on the rocks of Chaussey, frequented 

 only by stone-workers, where, sheltered by a mere hut, they 

 collected more than 600 species of the Crustacea, MoUusca, 

 and Zoophytes of the EngHsh Channel, 400 of which are either 

 new or imperfectly known. They have ascertained that the 

 Ascidiae are all born separately ; they swim rapidly, and, at the 

 end of a few days, some fix themselves to the mass from which 

 they sprung, and others form new colonies. These naturalists 

 have, as well as M. de Blainville, confirmed the idea, that the 

 animals called Flustrae approach the Ascidiae much more than 

 the Polypi, as Spallanzani imagined. They have also strength- 



