198 J. A. UDDEN 



can be made to settle in heaps which will have a noticeable 

 resemblance to these peculiar fossils. This new interpretation 

 of an obscure class of objects is given merely as an aid in their 

 study. Though the holothurians are referred to as the animals 

 most likely to produce coprolites of this kind, it is believed that 

 any other mud-eating species of burrowing habits may just as 

 well have done the. work — soft animals, perhaps, that were suf- 

 ficiently protected by their concealment in the ocean mud to 

 render unnecessary any hard parts, which might have left less 



uncertain traces of their existence. 



J. A. Udden. 

 Rock Island, III. 



