Dec. 1, 1866.] 



HAllDWICKE'S SCIENCE-GOSSIT. 



27 ( J 



mouth. The last of the swallows I saw were a pair 

 of belated individuals flying languidly about the 

 streets of Blandford on the 9th November. — W. G. 



Strength of the Sexton Beetle. — So strong 

 and persevering are these insects, that a single 

 beetle succeeded in burying a mole in two days. 

 Now, the mole is at least forty times as large as the 

 beetle, so that we can estimate the strength and 

 perseverance of the beetle by calculating the labour 

 which would be necessary for a man to inter, in two 

 days, an animal forty times as large as himself. 



Ravages or the Shipworm (Teredo navalis).— 

 The ravages committed by this creature are almost 

 incredible. Wood of every description is devoured 

 by the shipworm, whose tunnels are frequently 

 placed so closely together that the partition between 

 them is not thicker than the paper on which this 

 account is printed. As the Teredo bores, it lines 

 the tunnel with a thin shell of calcareous matter, 

 thus presenting a remarkable resemblance to the 

 habits of the white ant. When the Teredos have 

 taken entire possession of a piece of timber, they 

 destroy it so completely, that if the shelly lining 

 were removed from the wood, and each weighed 

 separately, the mineral substance would equal the 

 vegetable in weight.— Rev. J. G. Wood's "Homes 

 without Hands." 



GEOLOGY. 



Eossil Spider.— Dr. Bxemer has recently de- 

 scribed and figured a very perfect specimen of a 

 spider from the coal formation of Upper Silesia. It 

 is called the Protolycosa anthracophila, a name that 

 implies a near relation in general habit to the modern 

 Lycosa. The body is about an inch long. — Ann. Nat. 

 Hist., vol. xviii. p. 428. 



Geological Importance of Dreissena Poly- 

 morpha and on its presence in the delta of 

 Danube, as also in the Lakes and Lagoons in 

 that Region. — The centre from which this remark- 

 able bivalve has dispersed itself, now distributed in 

 nearly all the fresh waters of Europe, is the 

 depressed area situated between the Black and the 

 Caspian Seas. It there inhabits, in myriads, the 

 running and stagnant fresh waters, aud even the 

 brackish waters strongly impregnated with salt, as 

 those of the Lake Babadagh, the lagoon of Rasim, &c. 

 It occurs in a fossil state in the " drift-loam " of 

 Bessarabia, associated, as in the living state, with the 

 same species of Cardium, Didacna, and Adacna. 

 According to Captain Spratt, the Dreissena poly- 

 morpha abounds in the " loam " near Ismail, upon 

 the borders of Lake Yalpuk, where it is associated 

 with Didacna crassa, Eichwald (which, according to 

 that author, is not found living in the Caspian), a 

 Cardium not essentially distinct from C. rusticum, 



Cheninz, and a number of species of gastcropods 

 inhabiting at the present day these regions. These 

 deposits of loam, the stratigraphical position of 

 which is undoubtedly proved by their elevated 

 position, as well as by the great, number of terrestrial 

 mollusks, characteristic of the diluvial deposits of 

 the Danube, and the remains of Blephas primigenius 

 and other terrestrial mammals which are contained 

 in them, clearly point to the remote origin of 

 Dreissena polymorpha, and at the same time prove 

 that they constitute a link between the present con- 

 ditions prevailing in that region and the beds with 

 Dreissena in the Danubian basin, the most recent of 

 the deposits of the Miocene epoch. A comparative 

 examination of an extensive series of specimens in 

 the Imperial Museum of Vienna has resulted in the 

 association under one specific title of the Dreissena? of 

 the Miocene period with Dreissena polymorpha. Be- 

 sides some living forms which have received specific 

 names, as D. cochlcata, Kickx, of the Antwerp basin, 

 and several types not separable from D. spathulata, 

 Partsch, and especially the small Dreissena; of Bisenz, 

 and Garga (Moravia), associated with D. triangularis, 

 Melanopsides, and other species characteristic of the 

 beds with Dreissena, are specifically identical with 

 D. polymorpha ; even D. spathulata, D. Basteroli, 

 and D. subcarnata very greatly resemble distorted 

 individuals of this species from the lagoons on the 

 shores of the Black Sea. The Zebra Mussel lives 

 at the present day in fresh-water basins, with slightly 

 brackish water bottom ; it may be therefore inferred 

 that the Miocene beds with Dreissena had been 

 deposited from fresh -water accumulations and 

 brackish bottoms. The east of Europe and the 

 west of Asia alone present these conditions, aud 

 from these regions the fauna has moved towards the 

 west, as far as the Vienna basin, proofs of which 

 have long since been furnished by many celebrated 

 Austrian geologists. Not a single species of the 

 genus is met with in those fresh-water basins of the 

 Miocene epoch, which were not in direct communi- 

 cation with the brackish water areas of the East ; 

 and the recent diffusion of Dreissena polymorpha 

 over Central and Western Europe is due to transport 

 by movements of navigation. — Abstract of a Paper 

 by Dr. Peters, read before the Academy of Science at 

 Vienna. Communicated by R. Tate, F.G.S. 8fC 



Chalk Markings. — Since making an inquiry on 

 the above subject, at page 202 of Science Gossip, I 

 have met with the following passage in Mantell's 

 "Geological Excursions," page 130 : — " The only 

 metallic substances observable (in chalk) are oxide of 

 manganese in the state of dendritical or arborescent 

 markings in the chalk and flints, aud sulphurets and 

 oxides of iron." This description agrees so well 

 with the appearance about which I inquired, that I 

 gladly accept it as an explanation of what has puzzled 

 me for years.- — W. F. 



