102 
other times only two very obscure ribs, and often no in- 
dication of either : the young state of the spinous variety 
has been referred to the Genus Solen, and it is very re- 
markable that Lamarck should not have discovered its 
relation to Saxicava rugosa. 
The specimens before us are from the Suffolk Crag, they 
were collected by the Rev. G. R. Leaths, and have all 
the visible characters of genuine Crag Fossils, but they 
agree in form with the recent species, and Mrs. Cobbold 
has sent us a small specimen which she found amongst 
others in holes in Septaria, immediately below the Crag 
at Holy wells, which would lead us to suspect them to be 
of comparatively modern extraction. The middle figures 
have some remains of the spines belonging to the variety. 
