144 



partly spiral (Spirilla) ; so, of these shells with sinuous septa, we have 

 the spiral (Ammonites), and the partly straight and partly bent, which 

 have not been yet noticed, and which I shall venture to place under the 

 following genus. 



LXXIX. Hamites. A multilocular hook-formed shell, with sinuous 

 septa, with no evident siphunculus. 



The uniform figure of these fossil shells sufficiently separate them from 

 every other genus ; and undoubtedly this separation would have been 

 made long before this, if sufficient attention had been paid to the real 

 forms which the fragments of this fossil possessed ; and if a sufficient 

 number had been obtained to have allowed the making of the necessary 

 comparison. 



One circumstance has particularly tended to mislead those who may 

 have been induced to make any inquiries on this subject. All the casts 

 of the fossils of this genus which I have met with, except one in sand- 

 stone from Wiltshire, are formed of a pyritous clay, which, when the 

 shell has been entirely removed, so readily gives the idea of having 

 been in a soft state, that the hooked form of the specimens have been 

 attributed to their having been bent and distorted whilst in that state. 

 Such an idea might even be readily excited by the specimen, Plate X. 

 Fig. 5, found in the stratum of green sand in Wiltshire. Plate X. Fig. 2, 

 shows a specimen, in which the first approximation to the hooked form 

 is observable. Plate X. Fig. 4, represents a specimen, in which the 

 turn of the hook is completely made ; and evidently in such a direction, 

 as could not have allowed of the formation of a spiral turn. In this spe- 

 cimen, enough of the smaller end of the fossil is left to show, that it 

 was continued in a straight direction from the bend. This, it may be 

 observed, is the termination in which alone we could have expected the 

 spiral turn ; but which, going off in a straight line after the bend, deter- 

 mines the hooked form to belong to this fossil. 



The specimen Plate X. Fig. 3, which I purchased from the Le- 

 verian Museum, and which had frequently been with me an object 



