on the Genera Orbicula and Crania of Lamarck, 407 



pressions and a rather obtuse process placed at the inner end 

 of a fissure near the centre. Hinge none. 



The animal has two ciliated arms or tentacula, and adheres bv 

 a muscle or ligament, which passes through the fissure. 



The character of the genus given by Lamarck is as follows : 



"Orbicule. Coquille orbiculaire, applatie, fixee et compos6e 

 de deux valves, dont l'inferieure tres mince adhere aux 

 corps qui la soutiennent. Charniere inconnue. 



" Orbiculier. Acephale sans pied et sans prolongemens tu- 

 buleux ; mais muni de deux bras alonges, (ranges, qui 

 s'etendent au gre de 1'animal, et qui rentrent dans la co- 

 quille en se roulant en spirale." 



It is here observable, that Lamarck says the animal has no 

 foot ; but I apprehend it would not be improper to call the 

 muscle or ligament which passes through the fissure near the 

 centre of the lower valve, and which is the only part by which 

 the shell is attached, by that name ; it certainly very much re- 

 sembles the foot of the animal inhabitant of Patella. 



The only species of this genus, with which we are at present 

 acquainted, either by description or figure, is the one upon which 

 Lamarck has founded the genus : he calls it 0. norvegica, and it 

 is described and figured by Muller in Zoologia Danica under the 

 name of Patella anomala : it is distinguished from O. lavis by its 

 having numerous radiated decussating stria?, of which that spe- 

 cies is destitute. How Muller, who knew well all its characters, 

 and had examined it in its living state, could do so much violence 

 to nature as to name it Patella*, I confess myself completely at 



a loss 



* " It is not easy to understand why that famous naturalist has so arranged it among 

 the Patella, instead of constituting a particular genus, since it does not belong to the 

 genus Patella, not only as being a bivalve, but also from the difference of the animal 



inhabitant. 



" The 



