246 



O. W. WILLCOX 



If the removal of the interior filling be cautiously effected, best with 

 the help of a gentle stream of water, there may sometimes be seen fragile, 

 calcified, arborescent forms which ramify through the concretion in 

 complete disregard of the interior partitions, and which are sometimes, 

 but not often, preserved beyond the outer periphery. The dotted lines 

 across two of the cross-sections in Fig. 5 indicate such arborescent 

 forms. They are doubtless fossil stems of plants which were evidently 

 present in the sand before the concretions were formed, and owe their 

 preservation within the concretions to the exclusion of the under- 



FlG. 3 



ground circulation, which has no doubt in most cases removed by solu- 

 tion the parts not so inclosed. If this be the true interpretation, their 

 presence is significant as showing that organic matter was formerly 

 more abundant in the sand, yet they make it exceedingly difficult to 

 beHeve that these concretions are fossilized remnants of elongate forms 

 of animal or vegetable life, since it is inconceivable how such forms 

 could have inclosed these calcified plants (if such they be) in the man- 

 ner observed; besides, they bear no resemblance to any known form 

 of life. 



Neither is there any reasonable probability that they have resulted 

 from the filhng of cracks and subsequent hardening of the fiUing 

 material. In the first place, they are found in loose sand, which 

 is certainly not a material in which to expect cracks of any kind; in 



