34 



Forty-second Annual Report on the 



" The inner flanks of the side ridges appear to be continuously 

 even surfaces, making an angle of 155° with the plane of the inter- 

 mediate spaces, and against these sloping flanks the surface of the 

 transverse undulations forms a decided, though very obtuse set oi 

 angles, just like waves rolling along an inclined plane in the direction 

 of its strike. The side ridges are rounded at the top, and while their 

 exterior flanks are more precipitous than the interior ones, they swell 

 out opposite to each transverse furrow, thus giving to the side ridges 

 a beaded or knotted aspect, each bead of the series standing opposite 

 a furrow. The highest part of these lumps ^ nbout three lines above 

 the bottom of the furrows, and about a line and a half above the 

 surface on which the track is impressed. 



" My naturalist friends to whom I have exhibited the specimens, 

 appear disposed to consider the tracks those of some species of 

 gigantic mollusk, and I am given to understand there is now living 

 some small mollusk, whose track presents a series of tranverse ridges 

 and furrows, without, however, the longitudinal ones. From the 

 resemblance of the track to a ladder, the name proposed for it is 

 Glimactichnites Wilsoni, the specific designation being given in compli- 

 ment to its discoverer, Dr. Wilson." 



