PATELLA. 235 



Gaza^ a Byzantine pMologist who flonrislied in 

 the 15th century, appears to have been the first to 

 give this shell the name of Patella. It was, notwith- 

 standing, called by the ancient name Lepas by other 

 writers, and even as late as 1616 by Colonna. Al- 

 drovandus included the genus with Balanus : Lister 

 had the merit of separating and distinguishing them. 

 Nor have all modern zoologists been uniformly success- 

 ful in recognizing the natural position of Patella among 

 the Mollusca. In the opinion of Lamarck it belongs to 

 the same family as Phyllidia ; but the gap between the 

 Pectinibranchs and Nudibranchs seems much too wide 

 to be bridged over by even his engineering. Most of 

 his followers placed Patella alongside of Chiton in the 

 order Cyclobranchiata. The present genus was for some 

 time the receptacle of miscellaneous and incongruous 

 organisms. Among these were Patella unguis, Linne 

 [Lingula), P. anomala, Miiller [Crania], P. orbiculata, 

 Walker (according to Mr. Norman " the calcareous disk 

 of the termination of a tentacle of Echinus ''), P. extinc- 

 torium and P. tricornis, Turton (opercula of species of 

 Serpula): Ancylus fluviatilis and ^. lacustris were also 

 placed in the same genus. Patella, as now restricted, is 

 very rich in species, although their tendency to vary is 

 so great that the number of those described by authors 

 is evidently excessive. All of them inhabit rocks and 

 shingly beaches, and are strictly littoral. The distri- 

 bution of the genus is world-wide. As to its fossil 

 ancestry, S carles Wood says, " Shells of this form have 

 early made their appearance, and several have been 

 figured from the secondary formations. ^^ De Montfort, 

 perhaps for the sake of variety, changed the generic 

 name to Patellus. 



