HATIDWICKE'S SCIENCE-GOSSIP. 



91 



theories in text-books on basaltic prisms are unten- ' 

 able and unnecessary." WillyouallowmetoreferMr. ! 

 R. Mallet, through your pages, to the Geographical I 

 Magazine for August and September last, where , 

 the same conclusion is reached by another road ? I j 

 have travelled over hundreds of miles of large level ! 

 tabular masses of basalt, cracked into every variety 

 of shape except the prismatic column ; it is now 

 said that, when these masses split by the con- 

 traction of cooling, the surface will divide itself 

 " into similar geometric figures of equal area, 

 which, on mechanical principles, must be hexa- 

 gons." It seems that, as all columnar basalt is in 

 small patches, and in localities from which over- 

 lying matter has been taken off by natural denuda- 

 tion, it owes its prismatic shape to pressure— an 

 individual cell in a honeycomb owes its form to the 

 pressure of six cells on its circumference, may not 

 the basaltic prism owe its shape to the same cause 

 — while the mass is kept from spreading by the 

 surrounding masses of other material ? There is 

 another point that requires greater accuracy ; Mr. 

 R. Mallet says that a splitting rigidity is attained 

 by basalt at a temperature "between 900° and 

 600° Eahr." Mr. H. Woodward, in the Geological 

 Magazine, No. 114, tells us that " nearly 800° Ffhr. 

 would produce " aqueo-igneous fusion." It could 

 not split in this condition! Basalt coutains in 

 its constitution matter that can be converted into 

 bassan by the action of fire, or that is soluble in 

 water, — no fire-made rock could contain these mate- 

 rials \—H. F. Malet, Florence. 



NOTES AND aUERIES. 



Aquaria. — Having passed through the difficulties 

 which seem to annoy " W. II. S.," I am desirous to 

 suggest some things which appear to me to cause 

 his failures. I understand from the animals and the 

 plant (oalisneria) he mentions that his is a fresh- 

 water aquarium. From the suggestion of his friends 

 too, I should suppose, at the outset, his difficulties 

 arose from over-growth of conferva;, and that the 

 water was becoming like "pea-soup," as some 

 authorities compare it when in this state. If this 

 should be the case, simply screening the aquarium 

 from the light would correct it. iuen again, if it 

 has not sufficient light, the conferva; would become, 

 as he says, "white" and "slimy." But the con- 

 ferva;, or slimy matter on the stones and sides of 

 the glass, is essential to the life of the animals and 

 the well-being of li is aquarium. Oxygen cannot be 

 supplied to the animals it contains sufficiently with- 

 out it. Therefore to scrub or clean the glass, shells, 

 &c, is only taking from them that which should be 

 the life of the fishes, &c. I should recommend him 

 to allow the substance he calls slime, but which I 

 think must be conferva?, to remain, and wait ; it will 

 become green in a little time, and will then be the 

 very life of his aquarium. But it would be well not 

 to allow many fish to be in the aquarium until the 

 conferva; have grown. These things I long strug- 

 gled with myself; but I have now thoroughly over- 



come them. I found it best to put the fish in one 

 or two at a time, and watch if they were comfort- 

 able, and that they did not seek the surface lor 

 air— P. jr. 



Hedgehogs Carnivorous.— Having kept a pair 

 of hedgehogs and young for two years, I can verify 

 the statement of " W. Sharp " that they arc carni- 

 vorous and almost omnivorous. My little boy once 

 caught a frog iu the kitchen, and gave it to a young 

 hedgehog we had ; when it seized it and tore at it 

 like a cat ; and so fierce was it that the little boy, 

 much amused, attempted to take the frog from it, 

 and lifted the hedgehog from the ground before it 

 would relinquish its hold, and not even then. Many 

 times after he brought the hedgehogs birds, toads, 

 frogs, mice, and lizards, which were all alike de- 

 voured with much relish. They come out after 

 dusk and run about ; and when milk is on the fire 

 for their suppers they always know, and come out 

 accordingly. Nor is this ail; I have caught the 

 rebels more than once gnawing at my boots, and 

 often would they pick up a child's stocking and 

 drag it into their nest. — P. JV. ,, 



Marine Parasites.— If he does not possess the 

 work, it may be useful to " Mr. McGann" to learn 

 that Gosse, in his " Marine Zoology," describes the 

 Epizoa as " usually living attached to the gills or 

 to the interior of the mouth of fishes," and the 

 parasitic Entomostraca; as "creeping on the surface 

 of the body." The following fish have species 

 attached to . them : Shark, ray, sunfish, halibut, 

 turbot, brill, seabream, mackerel, gurnard, dory, 

 angler, sole, sprat, salmonida;, &c. Some species 

 are found on whales and other Cetacea, and some 

 in the sac of Ascidia, on the gills of the lobster, 

 and beneath the carapace of prawns and allied 

 Crustacea. Also in White's " Popular British 

 Crustacea" several species are figured and de- 

 scribed. — G. 67., Fentnor. 



Caterpillars of Goat-motii. — The return of 

 February reminds me of some Goat-moth Cater- 

 pillars which I found this time last year in an 

 unusual position. They were coiled up and enclosed 

 in a very thin and loosely-spun silk cocoon, lying 

 underneath a sandstone iu the grass, by the side of 

 a country lane. The nearest trees were oak, but 

 were about twenty yards off, and there was a ditch 

 on each side of the lane to be crossed first. The 

 larva; were apparently full grown, but had left no 

 trace of their burrow, since the hole under the stone 

 was only just sufficient to hold them. I placed 

 them in a pot of earth, into which they burrowed 

 immediately, and did not show themselves till the 

 imagos came out on the 10th and 11th of July. — 

 J. T. G., Rock Ferry. 



Gooseberry Caterpillar. — I have been sur- 

 prised to see the ignorance displayed by correspon- 

 dents as to this insect. In the January number, 

 "H. E. Watney " declares it to be the larva of the 

 Currant or Magpie-moth ; and in that of February 

 "A. N." says it is nothing of the kind, but it is the 

 larva of "a small, dingy, yellow fly." Now both of 

 these suppositions (I cannot think them more) are 

 wrong: the insect is neither more nor less than the 

 larva of the V. moth, one of the common Geometra;, 

 as will be seen if any one takes the trouble to rear 

 one or two of them. — Castle Barnes. 



Water-docks.— The attention which has been 

 recently directed to Rnmex maximus, and its inclu- 



