No. 11. SFONDYLUS. 

 Artichoke-head Shell. Inhabitant a Tethys. 



Shell with unequal valves, hard and rigid hinge, with two recurved teeth, 

 and a small hollow between. The Linnsean Spondyli are few in number, 

 the last edition of the Systema Naturae comprehending no more than four 

 species. Rumphius, Argenville, Seba and Davilla rank the Spondyli as 

 Oyster; while Lister, Gualteri, Linnaeus, Da Costa, &c, consider them as 

 constituting a distinct genus, under the name of Spondylus: there are now 10 

 species known. The Spondyli form in their exterior (generally) an interme- 

 diate family between the Ostrea and Pecten. 



Lamarck divides this genus into two, viz. Spondylus and Plicatulus. The 

 Spondylus has ears, but the Plicatula are without; this constitutes an essential 

 distinction, but it is not the only one. A striking character is drawn from the 

 structure and appearance of the back of the lower valve, which projects be- 

 yond the beak of the upper one, and, in Spondylus, exhibits a plain, triangular, 

 flat space, divided by a furrow; while, in the genus Plicatula, the beak has 

 no such characteristic space, or flat surface; and the edges are rumpled or 

 folded. These new genera are well exemplified in the two Linnaean shells, 

 Spondylus gedaropus, and Spondylus plicatulus. 



The name Spondylus is derived from gttovSuXiS) signifying an artichoke, 

 to which plant some small resemblance may be traced. 



These shells are found at a considerable depth in the ocean, firmly attach- 

 ed to rocks, particularly on the coasts of the Mediterranean, where the animal 

 is eaten as food. The colors of the Spondylus, which are orange, purple, &c, 

 are sometimes extremely brilliant. 



DIVISION I. Shell armed with spines or ramifications. 

 Family 1st. Sharp spines. 



Scientific name. Locality. Scientific name. Locality. 



Gsedaropus, Amboyna, W. Indies. Citrinus, East Indies. 



Regius, India. Histrix, Indian Seas. 



Aurantius, Mauritius. 



