534 DESCRIPTION OF THE MUSEUM. 



Brasilian coast, presented to the Museum by 

 M. Langsdorff, Next to it is placed the encrinus 

 or medusa-head, one of the rarest specimens in 

 the cabinet ; it was caught in the gulph of Mexico 

 at a considerable depth ; there is only one other 

 known in Europe ; its form is that of a tree with 

 the branches horizontally spread. Fossil encrini 

 are abundant in the strata of secondary forma- 

 tion. The name of fossil palm-tree is given to the 

 entire animal, and to its separate parts according 

 to their form, those of trochites and star-stone. 



The second order, the tubiferi, has been esta- 

 blished after the observations of M. Savigny We 

 have but two species of the order lobularia, all 

 the others belonging to that order are wanting in 

 the collection. The /. digitata was found in the 

 Atlantic, and the Lpalmata in the Mediterranean. 



The third order, that of the polypi with a solid 

 envelope, is by far the most numerous, and our 

 collection is very rich. We shall begin with 

 those of a small size placed in the frames, and 

 afterwards examine the larger specimens ar- 

 ranged in the chests below. M. de Lamarck has 

 subdivided this order into seven sections: the 

 polypi incrmtatiy corticati, lamelliferi, forami- 

 nosi, reticulati, vaginiformes , andjluviatiles. 



The genera alcyoniwn, spongia, jlcibellaria, 

 and penicillus compose the first section. We 



