BIOLOGY. * 271 







with horny bristles. How, then, do they bore ? Mr. Lankester 

 maintained that it was by the carbonic acid and other acid excre- 

 tions of their bodies, aided by the mechanical action of the bris- 

 tles. The selection of a material soluble in these acids is most 

 noticeable, since the softest chalk and the hardest limestone are 

 bored with the same facility. This can only be by chemical ac- 

 tion. If, then, we have a case of chemical boring in these worms, 

 is it not probable that many molluscs are similarly assisted in 

 their excavations? Mr. Lankester did not deny the mechanical 

 action in the pholas and other shells, but maintained that in many 

 cases the cooperation of acid excreta was probable. The truth 

 was to be found in a theory which combined the chemical and 

 mechanical view. 



THE WOODPECKER'S FORESIGHT. 



The woodpecker in California is a storer of acorns. The tree 

 he selects is invariably of the pine tribe. He bores several holes, 

 differing slightly in size, at the fall of the year, and then flies 

 away, in many instances to a long distance, and returns with an 

 acorn, which he immediately sets about adjusting to one of the 

 holes prepared for its reception, which will hold it tightly in its 

 position. But he does not eat the acflrn, for, as a rule, he is not a 

 vegetarian. His object in storing away the acorn exhibits fore- 

 si*ht, and knowledge of results more akin to reason than to in- 



^5 ^^ 



stinct. The succeeding winter the acorn remains intact, but be- 

 coming saturated with rain, is predisposed to decay, when it is 

 attacked by maggots, who seem to delight in this special food. 

 It is then that the woodpecker reaps the harvest his wisdom has 

 provided, at a time when, the ground being covered with snow, 

 he would experience a difficulty, otherwise, in obtaining suitable 

 or palatable food. It is a subject of speculation why the red-wood 

 cedar or the sugar-pine is invariably selected. It is not probable 

 that the insect, the most dainty to the woodpecker's taste, fre- 

 quents only the outside of two trees ; but so it is, that in Calave- 

 ras, Mariposa, and other districts of California, trees of this kind 

 may be frequently seen covered all over their trunks with acorns, 

 when there is not an oak-tree within several miles. A. B. Barton. 



SILUROID FISHES. 



At a recent meeting of the Boston Society of Natural History, 

 Professor Agassiz stated that he had recently been reviewing the 

 siluroid fishes, for the sake of illustrating the definitions he had 

 long since presented for the different categories of structure 

 among animals. The siluroids had always been considered a nat- 

 ural group ; placed, at first, in a single genus, which was subse- 

 quently divided into two, they were next considered a family in- 

 cluding several genera, and finally an order, embracing several 

 groups termed families. Was there, then, no meaning in the 

 terms genus, family, order? 



Ho urged strongly that the application of these terms should be 



