lEllEBRATULA* 



eould not possibly deposit testaceous matter in sticii a 

 osition as to form what he has thus termed a " support/1 

 ut which should more properly he called another valve;] 

 consequently, his Cabochons ayant un support connu" 

 should be placed among* the Conchifera, or we must sup- 

 pose the absurdity of a Gasteropoda depositing shelly matter 

 from the lower part of its foot^ Where it is not furnished 

 with the necessary organs. 



The Terebratulfe are placed by Linne among the 

 Anomia3; they are, however, very easily distinguished, 

 and have, therefore, been long separated from them: 

 they form a Genus of p'nmary importance to the Geolo- 

 gist, because they are found in a fossil state in all the 

 secondary and tertiary beds, beginning with the very 

 oldest, from which circumstance Lamarck concludes that 

 they have inhabited the depths of the ocean, and conse- 

 quently that they are generally pelagic shells. There are 

 a great number of species, both recent and fossil, but 

 particularly of the latter; these might perhaps be advan- 

 tageously divided into several genera, though we believe 

 if any attempt at such a division v/ere made, it would be 

 extremely difficult to assign to each Genus its proper 

 limits. We shall, therefore, be contented with pointing 

 out the characters of the Genus, and those peculiarities 

 by which it is distinguished from other genera that have 

 been confounded with it, or that are nearly related to it. 



Shell inequivalve, equilateral, very variable in gene- 

 ral form, being sometimes nearly egg-shaped, sometimes 

 very flat, particularly when in a young state, but gene^ 

 rally rather triangular and gibbous, attached to sub- 

 marine rocks, stones, &c. by a short tendinous peduncle 

 formed of numerous closely united fibres, which, however, 

 separate a little at the attached end. The umbo of one 

 yalve, which may properly be called the upper valve, is 

 more or less produced, frequently incurved, perforated at 

 its apex^ or notched at it^ inner edge, with a small curved 

 tooth on each side of its hinge^ which fits into a cor- 

 responding hollow in the other valve, in such a manner 

 that the two valves cannot be separated without breaking 

 either these teeth or the edges of their sockets. The in- 

 side of the other valve is furnished with two slender 

 shelly processes (generally called cartilages^ but really of 



