HARDWICKE'S SCIENCE-GOSSIP. 



249 



treal, where they rest on the Laurentian and pass under 

 the Potsdam sandstone, valley of St. Lawrence near 

 Quebec, at the Bay of St. Paul, Bay of Seven 

 Sisters on the coast of Labrador, and on the shore of 

 Lake Huron. 



HURONIAN. — A series of rocks first so named by the 

 American survey in 1855 on account of their occurring 

 on the north shore of Lake Huron. 



Nature of Rocks. — This system presents us with 

 rocks of the most variable nature : in places there are 

 masses composed of quartz and orthoclase felspar, 

 which are either simple jasper-petrosilex, eurite, or 

 porphyritic eurite, and in gneissose or schistose forms 

 or in irregular masses ; while in other parts the pre- 

 dominant rocks are diorites or diabases, passing into 

 chloritic or talcose schists and serpentines with epidote. 

 The limestones are mostly dolomitic. 



The Huronians are very rich in ores of which the 

 most important are copper, nickel, and iron. 



Thickness.— Estimated by Henry Hunt at from 

 15,000 to 20,000 feet. 



Localities.— North shore of Lake Huron, Lake 

 Superior, Newfoundland, the Green Mountains, Blue 

 Ridge and Rhodes Isle. 



Mont Albian. — Name applied by the survey of 

 Canada in 1872 to a series of crystalline schists well 

 developed in the White Mountains. 



Nature of Rocks. — Fine grained gneisses breaking 

 along lines of muscovite are the prevalent rocks ; 

 hornblende is often an important constituent, so much 

 so as in places to make the gneiss graduate into horn- 

 blende rock. In the lower part of the series there are 

 large masses of granular olivine and chrysolite rock 

 which are often accompanied by enstatite and 

 serpentine. 



Thickness. — Not yet determined. 

 Localities. — The White Mountains, Baltimore, 

 Washington, North Michigan, North and South 

 Carolina and Georgia. 



Having now obtained a general insight into the 

 American Pre-Cambrians, we will in a future article 

 endeavour to unravel our British and other European 

 types. 



A WOOD-CARVER'S EXPERIENCES OF 

 THE DEATH-WATCH BEETLE. 



"W fORMEATEN ! " What a common house- 

 V V hold word ! The smallest sign of the 

 earliest stage of the nuisance is often so deceptive 

 that irremedial mischief is complete before it is 

 discovered. The rough hewn timber of lordly 

 mansions, and the delicate frames of miniature 

 uortraits equally and rapidly become a prey to the 

 ravages of the "Death- Watch ;" the dark and damp 

 framework of cellars, the intermediate joists, ceilings, 

 flooring and panelling, the strongest supporting 

 beams, the heated principals and rafters of roofs, 



the exterior boarded portions of every class of 

 buildings ; the stillness of death, the rapidity of re- 

 volving machinery ; the resting furniture of closed 

 mansions, the active, and daily dusted and polished 

 furniture of business houses. The very articles of 

 hourly use scrubbed and scoured with boiling water, 

 even to workmen's planes and wooden mallets in 

 constant use— all succumb. 



In my daily calling as a wood-carver, I have had 

 frequent experience of the presence and ravages 

 of the "Death-watch." I remember as a child 

 hearing its well-known " tick " with peculiar terror, 

 accompanied with a variety of fully authenticated 

 proofs of its reality. I happen to reside in an old 

 timbered house abounding with several varieties of 

 the Anobium, or death-watch beetle. My most fre- 

 quent contact has been with the larvae of Anobiia/i 

 tessettatum and Anobium striatum, which I have 

 often taken from out of their burrows in wood of 

 all descriptions. I have placed some in confinement 

 in a smooth oak box covered with glass, to test 

 their ability of being again able to penetrate the 

 wood. This they can only do with assistance, such 

 as puncturing a hole with a bradawl and placing 

 them within it. Very soon they are out of sight, 

 throwing back their dusty labour. I have found 

 the perforations varying from T 2 6 inch to the size 

 of a No. 8 sewing-needle — these latter sizes being 

 the clue to the first entry of the larva. After pass- 

 ing through its transformation-state to the perfect 

 beetle, it emerges from its burrows for breeding 

 purposes, unfolding its delicate and pretty gauze wings 

 for flight ; only in this state have I been able to 

 detect its power or desire to use ticking or love-call. 

 I feel some uncertainty whether these two above- 

 mentioned species possess this power at all, although 

 they are credited with it. If you touch them they turn 

 upon their backs and simulate death ; but when the 

 time comes for depositing their eggs, they become 

 unusually active and fly from place to place, seeking 

 the surface of all kinds of wood, and attaching their 

 eggs in a secure manner. There the larvae are hatched, 

 possessed of all the power of an adult to eat their way 

 out of their shells, and into their native home, leaving 

 the egg-shells as e\idence that the work of destruction 

 has begun. 



The full-sized Anobium tessellatum measures about 

 \ inch in length, f s at its head, tapering to less 

 than half its size at the tail. It possesses powerful 

 curved jaws working from right to left when gnawing. 

 The body consists of a tough skin and twelve segments 

 capable of contracting and expanding and lapping 

 over each other. The ridges are covered with rough 

 hairs ; the feet have a small black claw at the tips 

 resembling those of a mole. Its entire construction 

 seems beautifully and perfectly adapted for its habits 

 of life. On turning the insects out, they showed a 

 disposition to curl up like a ball, bringing the tail 

 part between the claws and toward the main side 



