302 



THE GUIDE TO NATURE. 



lake, there outcrops a belt of highly 

 metamorphosed limestone. Limestone, 

 naturally, was just what the iron fur- 

 naces needed as a flux for the ore ; 

 hence, there are large quarries, now 

 abandoned, from which interesting 

 mineral specimens have come. Some 

 very fine calcite crystals, showing rare 

 forms, came from here some years ago. 

 Other minerals are : pyroxene (black 

 crystals, and white and pink diopside 

 crystals) pyrite crystals, pyrrhotite, 

 graphite, amphibole, wollastonite, or- 

 thoclase, titanite and brown tourmaline. 

 Rutile was also found, in a fine gemmy 

 crystal an inch long. There are more 



minerals at this locality than those - 

 given in the list, and some good ones 

 are easily obtainable, making attractive 

 specimens because of the white lime- 

 stone matrix. 



Glaciation is very prominent in this 

 region, and many of the limestone out- 

 crops on Crown Point are rounded and 

 polished in a way that is truly wonder- 

 ful, and covered with long, deep, paral- 

 lel scratches. Hand specimens are at- 

 tractive and often useful. Basalt dikes 

 often appear in the gneisses, but they 

 do not make good specimens because 

 the contacts are seldom welded ones. 





The Under Bark Grub. 



BY S. F. AARON, REDDEN, DELA. 



A very common larva inhabiting the 

 northern portions of the United States 



A CENTIPEDE ATTACKING AN UNDER-BARK 

 GRUB. 



and found under the decaying bark 

 of nearly every kind of tree has been 

 called the under bark grub. Go into 

 the woods, find any old, fallen log or 



decaying trunk, rip off the bark thereof 

 and in nearly every instance these yel- 

 lowish white, segmented larvae will 

 be seen within the shallow borings 

 that cut away merely the outer por- 

 tion of the wood. Flatness is the char- 

 acteristic of this insect stage. Nothing 

 that the writer knows of, excepting 

 neither the cockroach, silver bug nor 

 elater beetle, is nearly so thin from 

 front to back, or rather, from under- 

 neath to above, while the width of 

 each segment is about normal in com- 

 parison to the larva of the Coleoptera. 

 The flat head of the grub is brownish 

 black with rather small, sharp mandi- 

 bles for feeding on decaying wood. 

 The posterior segment is dark brown 

 and in miniature something like the 

 horns of a cow or like a small bent 

 forceps, the inner margin being almost 

 circular. The use of this forcep-like 

 appendage is not known ; the points 

 are not movable in opposition, and 

 therefore, cannot grasp anything. The 

 first three segments of the body have 

 each a pair of legs, the rest of the body 



