147 

 AMMOMTES fibulalu*. 

 TAB. CCCCVJl.~/7o. 2. 



Spec. Char. Depressed, ribed ; inner whorls 



almost wholly exposed • sides of the whorls 



liattened, their inner margins plain ; ribs 



numerous, united in pairs by smooth spines ; 



, aperture oblong-. 



Syn. Ammonites armatus ? Young and JBird, 

 Geol of Yorkshire, J). 2o0, t, 13, f. 9. 



A HE remarkable flatness of this shell, is encreased by 

 the spines filling up at intervals, thecoueave space around 

 the whorls ; tliere are now and tlien, ribs that pass over 

 the front without uniting with spines, these ribs are 

 more numerous in the latter whorls, and even alternate 

 with the spines ; each rib when it leaves the spine is 

 found divided into two, so that there are a greater num- 

 ber passing over the front, than exist upon the sides. 



Found at Whitby, where it is not of very rare occur- 

 rence. The smooth spines distinguish it well from A. 

 arraatiis of Min. Conch, tab. 95. but like it they are com- 

 posed of solid shell, and when broken otF, leave a flat- 

 ended tubercle, compared, together with the ribs, by 

 Young and Bird^ to a button and loop, whence its name. 



